Indonesia is one of the largest coconut-producing countries in the world.The utilization of coconut shell waste into briquettes will increase the selling value and become a great export opportunity.However,the effect ...Indonesia is one of the largest coconut-producing countries in the world.The utilization of coconut shell waste into briquettes will increase the selling value and become a great export opportunity.However,the effect of adhesives on the quality of coconut shell charcoal briquettes made using screw extruder machine has not been widely studied.This study aims to determine the effect of adhesive type on the quality of coconut shell charcoal briquettes.The process of fabricating briquettes in this study included crushing,mixing,blending,pressing,and drying.In the mixing process,3 types of adhesives were used,namely tapioca flour(Briquette_1),cassava flour(Briquette_2),and modified cassava flour(Briquette_3)with a concentration of 5%of the weight of coconut shell charcoal powders.The quality of the resulting briquettes and commercial briquettes will be evaluated by moisture content,ash content,volatile matter,fixed carbon,calorific value,density,compressive,and drop test testing.The results of this research showed that the type of adhesive had a significant effect on the quality of the briquettes produced.Specimen Briquette_1 had better quality than commercial briquettes(Briquette_4)and other briquette specimens.The test results showed that Briquette_1 produced briquettes with better compressive strength and friability than the other specimens,at 6.95 N/mm^(2) and 4.44%,respectively.The moisture content,ash content,fixed carbon,and calorific value of Briquette_1 have met the requirements set by the Indonesian National Standard(SNI)number 01-6235-2000.Meanwhile,the volatile matter content and density of Briquette_1 are by the standards of Japan and the United States America(USA).展开更多
Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(U...Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.展开更多
Purpose: The study was to evaluate the efficacy of cyanoacrylate tissue adhesive (CTA) application in corneal perforations. Method: This was a prospective study on 20 patients of corneal perforations who received cyan...Purpose: The study was to evaluate the efficacy of cyanoacrylate tissue adhesive (CTA) application in corneal perforations. Method: This was a prospective study on 20 patients of corneal perforations who received cyanoacrylate tissue adhesive application as treatment between March 2021 and March 2022 at Preah Ang Duong Hospital. The primary outcome measure was success rate of CTA application, while the secondary outcome was to measure postoperative best-corrected visual acuity (BCVA) and ocular complications. Results: The mean age of patients was 44.15 ± 16.05 years old and 7 (35%) were female. Causes of perforation were microbial infection in 12 patients (60%), trauma in 5 patients (25%), and sterile melting in 3 patients (15%). The perforation of size smaller than 1.5 mm was in 8 patients (40%) while 12 patients (60%) had perforated size between 1.5 mm to 3 mm. The perforation was 60% (12 patients) central, 25% (5 patients) paracentral, and 15% (3 patients) peripherally. Out of 20 patients, 5 patients (25%) received CTA application more than 1 time. The mean glue retention was 57.60 ± 31.84 days. Success rate of glue application (defined as intact globe without surgical intervention regardless of number of CTA applications) was 85%. At the last visit, 7 patients (35%) had BCVA of 6/120 or better. Common complications were uveitis (45%), ocular hypertension (30%), cataract (25%) and neovascularization (20%). No serious complications were found. Conclusion: Cyanoacrylate tissue adhesive is an effective treatment option in sealing corneal perforations with no serious complications. .展开更多
Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high tempera...Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high temperatures. Pre- or post-crosslinking is another method used to manufacture a conventional vinyl-based homopolymers or copolymers system with improved water resistance. Vinyl neodecanoate (VeoVa), N-methylolacrylamide (NMA), Methacrylamide, methacrylic acid (MAA), and other self-crosslinking comonomers are typically inserted to produce highly water-resistant vinyl based homopolymers or copolymers. Additionally, organic crosslinkers like glyoxal, glutaraldehyde, citric acid, tartaric acid, and the like, as well as inorganic crosslinkers like acidic metal salts like aluminium chloride, aluminium nitrate, boric acid, and the like, can be used to prepare the highly water-resistant vinyl based homopolymers or copolymers. It is also possible to combine the self-crosslinking comonomers with the organic crosslinkers. Recently, a different hybrid chemistry has been developed that improves lap shear strength, has outstanding water resistance, good durability, and doesn’t require any additional crosslinker agents. Two distinct polymers were combined to develop hybrid polymers. They usually involve mixing an organic polymer with a polymer. There are many capping agents that are used for polyurethanes to produce acrylics that are capped with polyurethane and used as an oligomer in PVAc wood glue. Here, in this paper, we reviewed the different hybrid chemistry based on polyurethane chemistry for wood bonding applications.展开更多
The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were ...The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.展开更多
Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conduct...Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conductivity. Two-dimensional graphene is a wonderful substance with exceptional qualities including high strength, high electrical conductivity, and large surface area. Because of these characteristics, graphene has been thoroughly researched for its prospective uses in a variety of industries, including electronics, energy storage, and biomedical engineering. The use of graphene as an additive in epoxy adhesives to enhance the characteristics of such materials is one of its promising uses. This paper reviewed the latest findings about graphene’s effects on epoxy adhesives. The various methods to produce graphene-epoxy composites and their improvements are discussed. This research additionally discusses the challenges associated with the production and processing of graphene-epoxy composites, as well as the mechanisms behind the improvements in mechanical, electrical, and thermal characteristics. The final section of this review discusses the challenges and prospective uses of graphene in epoxy adhesives in the future.展开更多
A novel strategy was developed to prepare the methacrylic gelatin-dopamine(GelMA-DA)/Ag nanoparticles(NPs)/graphene oxide(GO) composite hydrogels with good biocompatibility,mechanical properties,and antibacterial acti...A novel strategy was developed to prepare the methacrylic gelatin-dopamine(GelMA-DA)/Ag nanoparticles(NPs)/graphene oxide(GO) composite hydrogels with good biocompatibility,mechanical properties,and antibacterial activity.Mussel-inspired DA was utilized to modify the GelMA molecules,which imparts good adhesive performance to the hydrogels.GO,interfacial enhancer,not only improves mechanical properties of the hydrogels,but also provides anchor sites for loading Ag NPs through numerous oxygencontaining functional groups on the surface.The experimental results show that the GelMA/Ag NPs/GO hydrogels have good biocompatibility,and exhibit a swelling rate of 202±16%,the lap shear strength of 147±17 kPa,and compressive modulus of 136±53 kPa,in the case of the Ag NPs/GO content of 2 mg/mL.Antibacterial activity of the hydrogels against both gram-negative and gram-positive bacteria is dependent on the Ag NPs/GO content derived from the release of Ag^(+).Furthermore,the GelMA/Ag NPs/GO hydrogels possess good adhesive ability,which is resistant to highly twisted state when stuck on the surface of pigskin.These results demonstrate promising potential of the GelMA-DA/Ag NPs/GO hydrogels as wound dressings for biomedical applications in clinical and emergent treatment.展开更多
Background Reconstruction of damaged tissues requires both surface hemostasis and tissue bridging.Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies,makin...Background Reconstruction of damaged tissues requires both surface hemostasis and tissue bridging.Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies,making tissue bridging challenging.Methods This study proposes a tissue adhesive in the form of adhesive cryogel particles(ACPs) made from chitosan,acrylic acid,1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC) and N-hydroxysuccinimide(NHS).The adhesion performance was examined by the 180-degree peel test to a collection of tissues including porcine heart,intestine,liver,muscle,and stomach.Cytotoxicity of ACPs was evaluated by cell proliferation of human normal liver cells(LO2)and human intestinal epithelial cells(Caco-2).The degree of inflammation and biodegradability were examined in dorsal subcutaneous rat models.The ability of ACPs to bridge irregular tissue defects was assessed using porcine heart,liver,and kidney as the ex vivo models.Furthermore,a model of repairing liver rupture in rats and an intestinal anastomosis in rabbits were established to verify the effectiveness,biocompatibility,and applicability in clinical surgery.Results ACPs are applicable to confined and irregular tissue defects,such as deep herringbone grooves in the parenchyma organs and annular sections in the cavernous organs.ACPs formed tough adhesion between tissues[(670.9±50.1) J/m^(2) for the heart,(607.6±30.0) J/m^(2) for the intestine,(473.7±37.0) J/m^(2) for the liver,(186.1±13.3) J/m^(2) for the muscle,and(579.3±32.3) J/m^(2) for the stomach].ACPs showed considerable cytocompatibility in vitro study,with a high level of cell viability for 3 d[(98.8±1.2)%for LO2 and(98.3±1.6)%for Caco-2].It has comparable inflammation repair in a ruptured rat liver(P=0.58 compared with suture closure),the same with intestinal anastomosis in rabbits(P=0.40 compared with suture anastomosis).Additionally,ACP-based intestinal anastomosis(less than 30 s) was remarkably faster than the conventional suturing process(more than 10 min).When ACPs degrade after surgery,the tissues heal across the adhesion interface.Conclusions ACPs are promising as the adhesive for clinical operations and battlefield rescue,with the capability to bridge irregular tissue defects rapidly.展开更多
Soy protein adhesives are currently a hot research topic in the wood panels industry for the abundant raw material reserves,reasonable price and outstanding environmental features.But their poor water resistance,low b...Soy protein adhesives are currently a hot research topic in the wood panels industry for the abundant raw material reserves,reasonable price and outstanding environmental features.But their poor water resistance,low bonding strength and intolerance to mold are major drawbacks,so that proper modification before use is essential.Glutaraldehyde is one of the more apt cross-linking agents for soybean protein adhesives,which can effectively improve the bonding strength and water resistance of the adhesive.Equally,glutaraldehyde is also an efficient and broad-spectrum fungicide that can significantly improve the anti-fungal properties of a soy protein adhesive.In the work presented here,matrix assisted laser desorption ionization(MALDI-ToF)mass spectrometry and Fourier transform infrared spectroscopy techniques were used to analyze the reaction mechanism of glutaraldehyde cross-linking soybean protein.The results confirmed the reaction of the aldehyde group with amino groups of the side chains and the amide groups of the peptide linkages constituting the skeletal chain of the protein.The laboratory plywood and particleboard bonded with glutaraldehyde-soy bean protein adhesives were prepared to determine the adhesive bonding properties,the dry strength,24 h cold water soaking wet strength and 3 h hot water(63°C)wet strength of plywood were 2.03,1.13 and 0.75 MPa,respectively,which satisfied the requirements of industrial production.展开更多
Reproductive strategies and spawning habits play key roles in the evolution of endemic East Asian cyprinids.However,the molecular mechanisms underlying the regulation of spawning habits are not well understood.We rece...Reproductive strategies and spawning habits play key roles in the evolution of endemic East Asian cyprinids.However,the molecular mechanisms underlying the regulation of spawning habits are not well understood.We recently identified zona pellucida(Zp) as the top differentially expressed protein between East Asian cyprinids that produce adhesive and semi-buoyant eggs,suggesting that Zp protein may play important roles in the regulation of egg type.In this work,we generated transgenic zebrafish in which oocyte-specific expression of zp genes from rare minnow(Gobiocypris rarus),an East Asian cyprinid laying adhesive eggs,was driven by a zebrafish zp3.2 gene promoter.We found that the transgenic eggs obtained partial adhesiveness and exhibited alteration in hydration and buoyancy.Abnormal metabolism of vitellogenin(VTG) may contribute to enhanced hydration and/or buoyancy.Our work shows that expression of the exogenous zp3a gene from an adhesiveegg producing fish is sufficient to induce changes in both egg adhesiveness and buoyancy in zebrafish,emphasizing the important role of zp genes in the regulation of spawning habits.Our results thus provide new insights into how endemic East Asian cyprinids may have adapted to the Yangtze river-lake system via changes in spawning habits.展开更多
Osteoarthritis(OA)is the most common type of degenerative joint disease which affects 7%of the global population and more than 500 million people worldwide.One research frontier is the development of hydrogels for OA ...Osteoarthritis(OA)is the most common type of degenerative joint disease which affects 7%of the global population and more than 500 million people worldwide.One research frontier is the development of hydrogels for OA treatment,which operate either as functional scaffolds of tissue engineering or as delivery vehicles of functional additives.Both approaches address the big challenge:establishing stable integration of such delivery systems or implants.Adhesive hydrogels provide possible solutions to this challenge.However,few studies have described the current advances in using adhesive hydrogel for OA treatment.This review summarizes the commonly used hydrogels with their adhesion mechanisms and components.Additionally,recognizing that OA is a complex disease involving different biological mechanisms,the bioactive therapeutic strategies are also presented.By presenting the adhesive hydrogels in an interdisciplinary way,including both the fields of chemistry and biology,this review will attempt to provide a comprehensive insight for designing novel bioadhesive systems for OA therapy.展开更多
A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific...A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific foundations for the improvement and applications of Camellia oleifera protein adhesive by the reaction of model compounds.The experimental results demonstrate that,under alkaline conditions,formaldehyde is easier to react with Camellia oleifera protein by quicker reaction and lower curing temperature.Under acid conditions,amino hydroxymethylated structure of aliphatic series from LAG is difficult to form stable reactive intermediates and further polycondensation.Hydroxymethylation of end acylamino and peptide bond amino from LAG is relatively weak.Under alkaline conditions,the free aliphatic amino and acylamino of LAG both can make hydroxymethylation reaction with formaldehyde.In the polycondensation,hydroxymethyl amide is the initial structure and the reactive intermediate is produced by E1cb reaction of hydroxymethyl amide.Methylene bridge bonds and methylene ether bonds are structures of the polycondensation products,which are competing reactions.The former is mainly formed by the reaction between alkaline reactive intermediate and amino of aliphatic series,and the latter is produced by the reaction of reactive intermediate and amino of hydroxymethyl aliphatic series with hydroxymethyl amide.展开更多
By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,me...By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,mechanical interlocking,and electrostatic adsorption,are expounded.The research status of these materials in oil and gas drilling and production engineering field such as lost circulation prevention/control,wellbore stabilization,hydraulic fracturing,and profile control and water plugging,and their application challenges and prospects in oil and gas drilling and production are introduced comprehensively.According to the applications of functional adhesive materials in the field of oil and gas drilling and production at this stage,the key research directions of functional adhesive materials in the area of oil and gas drilling and production are proposed:(1)blending and modifying thermoplastic resins or designing curable thermoplastic resins to improve the bonding performance and pressure bearing capacity of adhesive lost circulation materials;(2)introducing low-cost adhesive groups and positive charge structures into polymers to reduce the cost of wellbore strengthening agents and improve their adhesion performance on the wellbore;(3)introducing thermally reversible covalent bond into thermosetting resin to prevent backflow of proppant and improve the compressive strength of adhesive proppant;(4)introducing thermally reversible covalent bonds into thermoplastic polymers to improve the temperature resistance,salt-resistance and water shutoff performance of adhesive water shutoff agents.展开更多
Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect o...Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect of hexamethylenediamine(HMDA)addition on the performance of liquefied wood(LW)adhesive for wood bonding is investigated.Differential scanning calorimetry showed the improved thermal stability and crosslinking of the LW adhesive with HMDA.The intensified presence of amide linkages(C–N bonds)was found in LW+HMDA with attenuated total reflection Fourier transform infrared spectroscopy.Analysis of the bonded joints using an automated bonding evaluation system showed that a higher press temperature resulted in stronger bonds for both types of adhesives.Moreover,the addition of HMDA to LW adhesive improved the bond strength of the joints and accelerated the crosslinking of the adhesive.However,with a tensile shear strength of(6.76±2.16)N×mm^(−2)(for LW)and(6.89±2.10)N×mm^(−2)(for LW+HMDA),both adhesives were found to be unsuitable for interior non-structural use.In addition,the acidity of LW resulted in relatively high wood failure(70%)in the adhesive joints tested.Improved crosslinking of LW with HMDA was reflected in improved resistance of LW+HMDA adhesive joints to water degradation.In conclusion,HMDA is a promising additive for improving the adhesive performance of LW adhesives.展开更多
The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and ...The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.展开更多
This brief article reviews a very particular and quite narrowfield,namely what has been done and what is needed to know for tannin adhesives for wood panels to succeed industrially.The present fashionable focus on bio...This brief article reviews a very particular and quite narrowfield,namely what has been done and what is needed to know for tannin adhesives for wood panels to succeed industrially.The present fashionable focus on bioadhe-sives has led to producing chemical adhesive formulations and approaches for tannin adhesives as a subject of academic publications.These,as good and original they might be,are and will still remain a rather empty aca-demic exercise if not put to the test of real industrial trials and industrial use.They will remain so without the“little”secrets and techniques outlined here that show that there is a great gap between developing an adhesive formulation in the laboratory and the hard reality to make it work where it does really count,in its industrial application.It outlines the fact that even more modern and excellent,newly developed bioadhesive formulations might well miserably fail once tried in the industry if the problems that always arise in their upgrading are not identified and solved,and solved well.It also outlines the fact that not only must costs always be taken into account and that a practical and possibly easy-to-handle approach must always be used,but too expensive or complex and unyielding adhesive systems are also often shown to be unusable or unsuitable in industry.展开更多
This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF...This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.展开更多
BACKGROUND Majority of adhesive small bowel obstruction(SBO)cases can be managed nonoperatively.However,a proportion of patients failed non-operative management.AIM To evaluate the predictors of successful non-operati...BACKGROUND Majority of adhesive small bowel obstruction(SBO)cases can be managed nonoperatively.However,a proportion of patients failed non-operative management.AIM To evaluate the predictors of successful non-operative management in adhesive SBO.METHODS A retrospective study was performed for all consecutive cases of adhesive SBO from November 2015 to May 2018.Data collated included basic demographics,clinical presentation,biochemistry and imaging results and management outcomes.The imaging studies were independently analyzed by a radiologist who was blinded to the clinical outcomes.The patients were divided into group A operative(including those that failed initial non-operative management)and group B non-operative for analysis.RESULTS Of 252 patients were included in the final analysis;group A(n=90)(35.7%)and group B(n=162)(64.3%).There were no differences in the clinical features between both groups.Laboratory tests of inflammatory markers and lactate levels were similar in both groups.From the imaging findings,the presence of a definitive transition point[odds ratio(OR)=2.67,95%confidence interval(CI):0.98-7.32,P=0.048],presence of free fluid(OR=2.11,95%CI:1.15-3.89,P=0.015)and absence of small bowel faecal signs(OR=1.70,95%CI:1.01-2.88,P=0.047)were predictive of the need of surgical intervention.In patients that received water soluble contrast medium,the evidence of contrast in colon was 3.83 times predictive of successful non-operative management(95%CI:1.79-8.21,P=0.001).CONCLUSION The computed tomography findings can assist clinicians in deciding early surgical intervention in adhesive SBO cases that are unlikely to be successful with non-operative management to prevent associated morbidity and mortality.展开更多
Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakth...Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakthrough to realize the goal of carbon peaking and carbon neutrality in the wood industry.In this study,a full biomass wood adhesive composed of tannin and sucrose was developed and applied successfully to the preparation of ply-wood.The preparation technique of plywood was optimized,and the chemical structure,curing performance,crystallization property and thermal performance of the adhesive were investigated.Results showed that:(1)hot-pressing temperature played a decisive role in the performances of tannin-sucrose composite adhesives and it also had a very significant influence on the water resistance of plywood.(2)The preparation of tannin-sucrose composite adhesive was a process in which sucrose was transformed into furan aldehydes and then made cross-linking reaction with tannin.These composite adhesives could only get good bonding performances when the curing temperature was above 210℃.(3)The optimal plywood preparation technique was:hot-pressing tem-perature of 220℃,hot-pressing time of 1.2 min/mm,m(tannin):m(sucrose)of 60:40,and adhesive loading of 160 g/m^(2).The wet bonding strength in boiling water of the prepared plywood was 0.83 MPa,meeting the strength requirements of Type-I plywood in the standard of GB/T 17657-2013.(4)The curing temperature of tannin-sucrose composite adhesive was further decreased by lowering the temperature during the transformation of sucrose into 5-HMF,which was a key in subsequent research.展开更多
Due to their lower environmental impact, ease of accessibility, low cost, and biodegradability, bio-renewable sources have been used extensively in the last several decades to synthesize adhesives, substituting petroc...Due to their lower environmental impact, ease of accessibility, low cost, and biodegradability, bio-renewable sources have been used extensively in the last several decades to synthesize adhesives, substituting petrochemical-based adhesive. Vegetable oils (including palm, castor, jatropha, and soybean oils), lactic acid, potato starch, and other bio-renewable sources are all excellent sources for the synthesis of adhesives that are being taken into consideration for the synthesis of “eco-friendly” adhesives. Due to their widespread use, accessibility, affordability, and biodegradability, biobased raw materials like carbohydrates used to synthesize wood and wood composite adhesive have gradually replaced petrochemical-based adhesive. Recently, xanthan gum, a naturally occurring polymer, has drawn the interest of scientists as a potentially petroleum source replacement. It possesses specific rheological characteristics, excellent water solubility, and stability to heat, and can be used as a binder, thickener, suspending agent, and stabilizer. Xanthan gum increases the adhesive strength in addition to increasing the viscosity of water-soluble adhesives. This article discusses xanthan gum as a potential substitute for traditional raw materials derived from petroleum that is used as a raw material for adhesives.展开更多
文摘Indonesia is one of the largest coconut-producing countries in the world.The utilization of coconut shell waste into briquettes will increase the selling value and become a great export opportunity.However,the effect of adhesives on the quality of coconut shell charcoal briquettes made using screw extruder machine has not been widely studied.This study aims to determine the effect of adhesive type on the quality of coconut shell charcoal briquettes.The process of fabricating briquettes in this study included crushing,mixing,blending,pressing,and drying.In the mixing process,3 types of adhesives were used,namely tapioca flour(Briquette_1),cassava flour(Briquette_2),and modified cassava flour(Briquette_3)with a concentration of 5%of the weight of coconut shell charcoal powders.The quality of the resulting briquettes and commercial briquettes will be evaluated by moisture content,ash content,volatile matter,fixed carbon,calorific value,density,compressive,and drop test testing.The results of this research showed that the type of adhesive had a significant effect on the quality of the briquettes produced.Specimen Briquette_1 had better quality than commercial briquettes(Briquette_4)and other briquette specimens.The test results showed that Briquette_1 produced briquettes with better compressive strength and friability than the other specimens,at 6.95 N/mm^(2) and 4.44%,respectively.The moisture content,ash content,fixed carbon,and calorific value of Briquette_1 have met the requirements set by the Indonesian National Standard(SNI)number 01-6235-2000.Meanwhile,the volatile matter content and density of Briquette_1 are by the standards of Japan and the United States America(USA).
基金supported by the Yunnan Provincial Natural Science Foundation (202201AU070222,202201AT070045,202101BD070001-074)Scientific Research Fund Project of Yunnan Provincial Department of Education (2022J0490)financed by the 111 Project (D21027).
文摘Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.
文摘Purpose: The study was to evaluate the efficacy of cyanoacrylate tissue adhesive (CTA) application in corneal perforations. Method: This was a prospective study on 20 patients of corneal perforations who received cyanoacrylate tissue adhesive application as treatment between March 2021 and March 2022 at Preah Ang Duong Hospital. The primary outcome measure was success rate of CTA application, while the secondary outcome was to measure postoperative best-corrected visual acuity (BCVA) and ocular complications. Results: The mean age of patients was 44.15 ± 16.05 years old and 7 (35%) were female. Causes of perforation were microbial infection in 12 patients (60%), trauma in 5 patients (25%), and sterile melting in 3 patients (15%). The perforation of size smaller than 1.5 mm was in 8 patients (40%) while 12 patients (60%) had perforated size between 1.5 mm to 3 mm. The perforation was 60% (12 patients) central, 25% (5 patients) paracentral, and 15% (3 patients) peripherally. Out of 20 patients, 5 patients (25%) received CTA application more than 1 time. The mean glue retention was 57.60 ± 31.84 days. Success rate of glue application (defined as intact globe without surgical intervention regardless of number of CTA applications) was 85%. At the last visit, 7 patients (35%) had BCVA of 6/120 or better. Common complications were uveitis (45%), ocular hypertension (30%), cataract (25%) and neovascularization (20%). No serious complications were found. Conclusion: Cyanoacrylate tissue adhesive is an effective treatment option in sealing corneal perforations with no serious complications. .
文摘Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high temperatures. Pre- or post-crosslinking is another method used to manufacture a conventional vinyl-based homopolymers or copolymers system with improved water resistance. Vinyl neodecanoate (VeoVa), N-methylolacrylamide (NMA), Methacrylamide, methacrylic acid (MAA), and other self-crosslinking comonomers are typically inserted to produce highly water-resistant vinyl based homopolymers or copolymers. Additionally, organic crosslinkers like glyoxal, glutaraldehyde, citric acid, tartaric acid, and the like, as well as inorganic crosslinkers like acidic metal salts like aluminium chloride, aluminium nitrate, boric acid, and the like, can be used to prepare the highly water-resistant vinyl based homopolymers or copolymers. It is also possible to combine the self-crosslinking comonomers with the organic crosslinkers. Recently, a different hybrid chemistry has been developed that improves lap shear strength, has outstanding water resistance, good durability, and doesn’t require any additional crosslinker agents. Two distinct polymers were combined to develop hybrid polymers. They usually involve mixing an organic polymer with a polymer. There are many capping agents that are used for polyurethanes to produce acrylics that are capped with polyurethane and used as an oligomer in PVAc wood glue. Here, in this paper, we reviewed the different hybrid chemistry based on polyurethane chemistry for wood bonding applications.
文摘The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.
文摘Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conductivity. Two-dimensional graphene is a wonderful substance with exceptional qualities including high strength, high electrical conductivity, and large surface area. Because of these characteristics, graphene has been thoroughly researched for its prospective uses in a variety of industries, including electronics, energy storage, and biomedical engineering. The use of graphene as an additive in epoxy adhesives to enhance the characteristics of such materials is one of its promising uses. This paper reviewed the latest findings about graphene’s effects on epoxy adhesives. The various methods to produce graphene-epoxy composites and their improvements are discussed. This research additionally discusses the challenges associated with the production and processing of graphene-epoxy composites, as well as the mechanisms behind the improvements in mechanical, electrical, and thermal characteristics. The final section of this review discusses the challenges and prospective uses of graphene in epoxy adhesives in the future.
基金Funded by the National Key Research and Development(R&D) Program of China(No.2018YFB1105702)。
文摘A novel strategy was developed to prepare the methacrylic gelatin-dopamine(GelMA-DA)/Ag nanoparticles(NPs)/graphene oxide(GO) composite hydrogels with good biocompatibility,mechanical properties,and antibacterial activity.Mussel-inspired DA was utilized to modify the GelMA molecules,which imparts good adhesive performance to the hydrogels.GO,interfacial enhancer,not only improves mechanical properties of the hydrogels,but also provides anchor sites for loading Ag NPs through numerous oxygencontaining functional groups on the surface.The experimental results show that the GelMA/Ag NPs/GO hydrogels have good biocompatibility,and exhibit a swelling rate of 202±16%,the lap shear strength of 147±17 kPa,and compressive modulus of 136±53 kPa,in the case of the Ag NPs/GO content of 2 mg/mL.Antibacterial activity of the hydrogels against both gram-negative and gram-positive bacteria is dependent on the Ag NPs/GO content derived from the release of Ag^(+).Furthermore,the GelMA/Ag NPs/GO hydrogels possess good adhesive ability,which is resistant to highly twisted state when stuck on the surface of pigskin.These results demonstrate promising potential of the GelMA-DA/Ag NPs/GO hydrogels as wound dressings for biomedical applications in clinical and emergent treatment.
基金supported by the National Natural Science Foundation of China (12102388, T2125009, 92048302)the National Key Research and Development Program of China 2017 (YFA0701100)the Fundamental Research Funds for the Central Universities (226-2022-00141, 2022QZJH52)。
文摘Background Reconstruction of damaged tissues requires both surface hemostasis and tissue bridging.Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies,making tissue bridging challenging.Methods This study proposes a tissue adhesive in the form of adhesive cryogel particles(ACPs) made from chitosan,acrylic acid,1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC) and N-hydroxysuccinimide(NHS).The adhesion performance was examined by the 180-degree peel test to a collection of tissues including porcine heart,intestine,liver,muscle,and stomach.Cytotoxicity of ACPs was evaluated by cell proliferation of human normal liver cells(LO2)and human intestinal epithelial cells(Caco-2).The degree of inflammation and biodegradability were examined in dorsal subcutaneous rat models.The ability of ACPs to bridge irregular tissue defects was assessed using porcine heart,liver,and kidney as the ex vivo models.Furthermore,a model of repairing liver rupture in rats and an intestinal anastomosis in rabbits were established to verify the effectiveness,biocompatibility,and applicability in clinical surgery.Results ACPs are applicable to confined and irregular tissue defects,such as deep herringbone grooves in the parenchyma organs and annular sections in the cavernous organs.ACPs formed tough adhesion between tissues[(670.9±50.1) J/m^(2) for the heart,(607.6±30.0) J/m^(2) for the intestine,(473.7±37.0) J/m^(2) for the liver,(186.1±13.3) J/m^(2) for the muscle,and(579.3±32.3) J/m^(2) for the stomach].ACPs showed considerable cytocompatibility in vitro study,with a high level of cell viability for 3 d[(98.8±1.2)%for LO2 and(98.3±1.6)%for Caco-2].It has comparable inflammation repair in a ruptured rat liver(P=0.58 compared with suture closure),the same with intestinal anastomosis in rabbits(P=0.40 compared with suture anastomosis).Additionally,ACP-based intestinal anastomosis(less than 30 s) was remarkably faster than the conventional suturing process(more than 10 min).When ACPs degrade after surgery,the tissues heal across the adhesion interface.Conclusions ACPs are promising as the adhesive for clinical operations and battlefield rescue,with the capability to bridge irregular tissue defects rapidly.
基金supported by the National Natural Science Foundation of China(31660176)the Yunnan Provincial Natural Science Foundation(202201AU070222)and Scientific Research Fund Project of Yunnan Provincial Department of Education(2022J0490)+1 种基金financed by the ERA-CoBioTech Project WooBAdh(Environmentally-friendly bioadhesives from renewable resources)by the Slovenian Ministry of Education.Science and Sport and the Slovenian Research Agency within the Framework of the Program P4-0015.
文摘Soy protein adhesives are currently a hot research topic in the wood panels industry for the abundant raw material reserves,reasonable price and outstanding environmental features.But their poor water resistance,low bonding strength and intolerance to mold are major drawbacks,so that proper modification before use is essential.Glutaraldehyde is one of the more apt cross-linking agents for soybean protein adhesives,which can effectively improve the bonding strength and water resistance of the adhesive.Equally,glutaraldehyde is also an efficient and broad-spectrum fungicide that can significantly improve the anti-fungal properties of a soy protein adhesive.In the work presented here,matrix assisted laser desorption ionization(MALDI-ToF)mass spectrometry and Fourier transform infrared spectroscopy techniques were used to analyze the reaction mechanism of glutaraldehyde cross-linking soybean protein.The results confirmed the reaction of the aldehyde group with amino groups of the side chains and the amide groups of the peptide linkages constituting the skeletal chain of the protein.The laboratory plywood and particleboard bonded with glutaraldehyde-soy bean protein adhesives were prepared to determine the adhesive bonding properties,the dry strength,24 h cold water soaking wet strength and 3 h hot water(63°C)wet strength of plywood were 2.03,1.13 and 0.75 MPa,respectively,which satisfied the requirements of industrial production.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31000000)。
文摘Reproductive strategies and spawning habits play key roles in the evolution of endemic East Asian cyprinids.However,the molecular mechanisms underlying the regulation of spawning habits are not well understood.We recently identified zona pellucida(Zp) as the top differentially expressed protein between East Asian cyprinids that produce adhesive and semi-buoyant eggs,suggesting that Zp protein may play important roles in the regulation of egg type.In this work,we generated transgenic zebrafish in which oocyte-specific expression of zp genes from rare minnow(Gobiocypris rarus),an East Asian cyprinid laying adhesive eggs,was driven by a zebrafish zp3.2 gene promoter.We found that the transgenic eggs obtained partial adhesiveness and exhibited alteration in hydration and buoyancy.Abnormal metabolism of vitellogenin(VTG) may contribute to enhanced hydration and/or buoyancy.Our work shows that expression of the exogenous zp3a gene from an adhesiveegg producing fish is sufficient to induce changes in both egg adhesiveness and buoyancy in zebrafish,emphasizing the important role of zp genes in the regulation of spawning habits.Our results thus provide new insights into how endemic East Asian cyprinids may have adapted to the Yangtze river-lake system via changes in spawning habits.
基金supported by the National Natural Science Foundation of China (52103184, 82102593)the China Postdoctoral Science Foundation (XJ2021051, 2020TQ0129, 2021M693960)+3 种基金the"Young Talent Support Plan"and Funding for Basic Scientific Research of Xi’an Jiaotong Universitysupported by a Grant from Science Foundation Ireland (SFI)co-funded under the European Regional Development Fund (13/RC/2073_P2)the funds received from European Union Horizon 2020 Programme (H2020-MSCA-IF-2017) under the Marie Sklodowska-Curie Individual Fellowship (797716).
文摘Osteoarthritis(OA)is the most common type of degenerative joint disease which affects 7%of the global population and more than 500 million people worldwide.One research frontier is the development of hydrogels for OA treatment,which operate either as functional scaffolds of tissue engineering or as delivery vehicles of functional additives.Both approaches address the big challenge:establishing stable integration of such delivery systems or implants.Adhesive hydrogels provide possible solutions to this challenge.However,few studies have described the current advances in using adhesive hydrogel for OA treatment.This review summarizes the commonly used hydrogels with their adhesion mechanisms and components.Additionally,recognizing that OA is a complex disease involving different biological mechanisms,the bioactive therapeutic strategies are also presented.By presenting the adhesive hydrogels in an interdisciplinary way,including both the fields of chemistry and biology,this review will attempt to provide a comprehensive insight for designing novel bioadhesive systems for OA therapy.
基金Funded by the National Natural Science Foundation of China (32160348)the Department Program of Guizhou Province (ZK[2021]162 and[2019]2325)+1 种基金the Special Project of“Doctor Professor Service Group of Kaili University (BJFWT201906)the Cultivation Project of Guizhou University of China ([2019]37)。
文摘A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific foundations for the improvement and applications of Camellia oleifera protein adhesive by the reaction of model compounds.The experimental results demonstrate that,under alkaline conditions,formaldehyde is easier to react with Camellia oleifera protein by quicker reaction and lower curing temperature.Under acid conditions,amino hydroxymethylated structure of aliphatic series from LAG is difficult to form stable reactive intermediates and further polycondensation.Hydroxymethylation of end acylamino and peptide bond amino from LAG is relatively weak.Under alkaline conditions,the free aliphatic amino and acylamino of LAG both can make hydroxymethylation reaction with formaldehyde.In the polycondensation,hydroxymethyl amide is the initial structure and the reactive intermediate is produced by E1cb reaction of hydroxymethyl amide.Methylene bridge bonds and methylene ether bonds are structures of the polycondensation products,which are competing reactions.The former is mainly formed by the reaction between alkaline reactive intermediate and amino of aliphatic series,and the latter is produced by the reaction of reactive intermediate and amino of hydroxymethyl aliphatic series with hydroxymethyl amide.
基金Supported by National Natural Science Foundation of China(51991361,52074327)Major Engineering Technology Field Test Project of CNPC(2020F-45)。
文摘By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,mechanical interlocking,and electrostatic adsorption,are expounded.The research status of these materials in oil and gas drilling and production engineering field such as lost circulation prevention/control,wellbore stabilization,hydraulic fracturing,and profile control and water plugging,and their application challenges and prospects in oil and gas drilling and production are introduced comprehensively.According to the applications of functional adhesive materials in the field of oil and gas drilling and production at this stage,the key research directions of functional adhesive materials in the area of oil and gas drilling and production are proposed:(1)blending and modifying thermoplastic resins or designing curable thermoplastic resins to improve the bonding performance and pressure bearing capacity of adhesive lost circulation materials;(2)introducing low-cost adhesive groups and positive charge structures into polymers to reduce the cost of wellbore strengthening agents and improve their adhesion performance on the wellbore;(3)introducing thermally reversible covalent bond into thermosetting resin to prevent backflow of proppant and improve the compressive strength of adhesive proppant;(4)introducing thermally reversible covalent bonds into thermoplastic polymers to improve the temperature resistance,salt-resistance and water shutoff performance of adhesive water shutoff agents.
文摘Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect of hexamethylenediamine(HMDA)addition on the performance of liquefied wood(LW)adhesive for wood bonding is investigated.Differential scanning calorimetry showed the improved thermal stability and crosslinking of the LW adhesive with HMDA.The intensified presence of amide linkages(C–N bonds)was found in LW+HMDA with attenuated total reflection Fourier transform infrared spectroscopy.Analysis of the bonded joints using an automated bonding evaluation system showed that a higher press temperature resulted in stronger bonds for both types of adhesives.Moreover,the addition of HMDA to LW adhesive improved the bond strength of the joints and accelerated the crosslinking of the adhesive.However,with a tensile shear strength of(6.76±2.16)N×mm^(−2)(for LW)and(6.89±2.10)N×mm^(−2)(for LW+HMDA),both adhesives were found to be unsuitable for interior non-structural use.In addition,the acidity of LW resulted in relatively high wood failure(70%)in the adhesive joints tested.Improved crosslinking of LW with HMDA was reflected in improved resistance of LW+HMDA adhesive joints to water degradation.In conclusion,HMDA is a promising additive for improving the adhesive performance of LW adhesives.
基金Funded by the National Natural Science Foundation of China(No.32160348)the Department Program of Guizhou Province(No.ZK[2021]162)+1 种基金the Guizhou Province Science and Technology Plan Project(No.[2020]1Y128)the Forestry Department Foundation of Guizhou Province of China(Nos.J[2022]21 and[2020]C14)。
文摘The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.
文摘This brief article reviews a very particular and quite narrowfield,namely what has been done and what is needed to know for tannin adhesives for wood panels to succeed industrially.The present fashionable focus on bioadhe-sives has led to producing chemical adhesive formulations and approaches for tannin adhesives as a subject of academic publications.These,as good and original they might be,are and will still remain a rather empty aca-demic exercise if not put to the test of real industrial trials and industrial use.They will remain so without the“little”secrets and techniques outlined here that show that there is a great gap between developing an adhesive formulation in the laboratory and the hard reality to make it work where it does really count,in its industrial application.It outlines the fact that even more modern and excellent,newly developed bioadhesive formulations might well miserably fail once tried in the industry if the problems that always arise in their upgrading are not identified and solved,and solved well.It also outlines the fact that not only must costs always be taken into account and that a practical and possibly easy-to-handle approach must always be used,but too expensive or complex and unyielding adhesive systems are also often shown to be unusable or unsuitable in industry.
基金financed under the scheme of Laboratory of Excellence ARBRE by the French Agence Nationale de la Recherche(ANR).
文摘This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.
文摘BACKGROUND Majority of adhesive small bowel obstruction(SBO)cases can be managed nonoperatively.However,a proportion of patients failed non-operative management.AIM To evaluate the predictors of successful non-operative management in adhesive SBO.METHODS A retrospective study was performed for all consecutive cases of adhesive SBO from November 2015 to May 2018.Data collated included basic demographics,clinical presentation,biochemistry and imaging results and management outcomes.The imaging studies were independently analyzed by a radiologist who was blinded to the clinical outcomes.The patients were divided into group A operative(including those that failed initial non-operative management)and group B non-operative for analysis.RESULTS Of 252 patients were included in the final analysis;group A(n=90)(35.7%)and group B(n=162)(64.3%).There were no differences in the clinical features between both groups.Laboratory tests of inflammatory markers and lactate levels were similar in both groups.From the imaging findings,the presence of a definitive transition point[odds ratio(OR)=2.67,95%confidence interval(CI):0.98-7.32,P=0.048],presence of free fluid(OR=2.11,95%CI:1.15-3.89,P=0.015)and absence of small bowel faecal signs(OR=1.70,95%CI:1.01-2.88,P=0.047)were predictive of the need of surgical intervention.In patients that received water soluble contrast medium,the evidence of contrast in colon was 3.83 times predictive of successful non-operative management(95%CI:1.79-8.21,P=0.001).CONCLUSION The computed tomography findings can assist clinicians in deciding early surgical intervention in adhesive SBO cases that are unlikely to be successful with non-operative management to prevent associated morbidity and mortality.
文摘Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakthrough to realize the goal of carbon peaking and carbon neutrality in the wood industry.In this study,a full biomass wood adhesive composed of tannin and sucrose was developed and applied successfully to the preparation of ply-wood.The preparation technique of plywood was optimized,and the chemical structure,curing performance,crystallization property and thermal performance of the adhesive were investigated.Results showed that:(1)hot-pressing temperature played a decisive role in the performances of tannin-sucrose composite adhesives and it also had a very significant influence on the water resistance of plywood.(2)The preparation of tannin-sucrose composite adhesive was a process in which sucrose was transformed into furan aldehydes and then made cross-linking reaction with tannin.These composite adhesives could only get good bonding performances when the curing temperature was above 210℃.(3)The optimal plywood preparation technique was:hot-pressing tem-perature of 220℃,hot-pressing time of 1.2 min/mm,m(tannin):m(sucrose)of 60:40,and adhesive loading of 160 g/m^(2).The wet bonding strength in boiling water of the prepared plywood was 0.83 MPa,meeting the strength requirements of Type-I plywood in the standard of GB/T 17657-2013.(4)The curing temperature of tannin-sucrose composite adhesive was further decreased by lowering the temperature during the transformation of sucrose into 5-HMF,which was a key in subsequent research.
文摘Due to their lower environmental impact, ease of accessibility, low cost, and biodegradability, bio-renewable sources have been used extensively in the last several decades to synthesize adhesives, substituting petrochemical-based adhesive. Vegetable oils (including palm, castor, jatropha, and soybean oils), lactic acid, potato starch, and other bio-renewable sources are all excellent sources for the synthesis of adhesives that are being taken into consideration for the synthesis of “eco-friendly” adhesives. Due to their widespread use, accessibility, affordability, and biodegradability, biobased raw materials like carbohydrates used to synthesize wood and wood composite adhesive have gradually replaced petrochemical-based adhesive. Recently, xanthan gum, a naturally occurring polymer, has drawn the interest of scientists as a potentially petroleum source replacement. It possesses specific rheological characteristics, excellent water solubility, and stability to heat, and can be used as a binder, thickener, suspending agent, and stabilizer. Xanthan gum increases the adhesive strength in addition to increasing the viscosity of water-soluble adhesives. This article discusses xanthan gum as a potential substitute for traditional raw materials derived from petroleum that is used as a raw material for adhesives.
