In this work,as-cast Mg-Ni-Y alloys were proposed to develop a feasible material for fracturing balls,and their mechanical performance and corrosion behavior were systematically investigated.Long period stacking order...In this work,as-cast Mg-Ni-Y alloys were proposed to develop a feasible material for fracturing balls,and their mechanical performance and corrosion behavior were systematically investigated.Long period stacking order(LPSO)phase was firstly introduced to improve both the mechanical properties and degradation rate of magnesium alloys.With the increase of LPSO phase,the compressive strength was improved significantly,while the elongation of the alloys decreased owing to the relatively brittle nature of LPSO phase.Due to the higher corrosion potential of LPSO phase,the LPSO phase can accelerate the corrosion process by providing more micro-couples.However,the LPSO phase would serve as the corrosion barrier between the corrosion medium and the matrix when the contents of LPSO phase are too high in Mg92.5Ni3Y4.5 and Mg87.5Ni5Y7.5 alloys.As-cast Mg97.5Ni1Y1.5 alloy with satisfactory mechanical properties and rapid degradation rate was successfully developed,exhibiting a high degradation rate of 6675 mm/a(93℃)in 3 wt.%KCl solution and a favorable ultimate compressive strength of 410 MPa.The degradation rate of Mg97.5Ni1Y1.5 alloy is 2-5 times of the current commercial magnesium alloy fracturing materials.展开更多
The apparent degradation rate constant of fluticasone propionate(FLT) in 0.1 M NaOH:methanol=1:1 at 37 °C was previously reported to be 0.169 ± 0.003 h^(-1), and four degradation products(products 1–4) were...The apparent degradation rate constant of fluticasone propionate(FLT) in 0.1 M NaOH:methanol=1:1 at 37 °C was previously reported to be 0.169 ± 0.003 h^(-1), and four degradation products(products 1–4) were observed in the solution. The aims of the present study were to assess the degradation rates of FLT in other alkaline solutions and clarify the chemical structures of the four degradation products in order to obtain basic data for designing an enema for inflammatory bowel disease. The apparent degradation rate constants in 0.05 M NaOH and 0.1 M NaOH:CH_3CN=1:1 were 0.472 ± 0.013 h^(-1) and 0.154 ± 0.000 h^(-1)(n=3), respectively. The chemical structures of products 1–4 in 0.1 M NaOH:methanol=1:1 were revealed by nuclear magnetic resonance(NMR)and mass spectrometry data. The chemical structure of products 2 was that the 17-position of the thioester moiety of FLT was substituted by a carboxylic acid. The degradation product in 0.1 M NaOH:CH_3CN=1:1 was found to be product 2 based on ~1H NMR data. The degradation product in 0.05 M NaOH was considered to be product 2 based on the retention time of HPLC. These results are useful for detecting the degradation products of FLT by enzymes of the intestinal bacterial flora in the large intestine after dosing FLT as an enema.展开更多
The purpose of this study is to investigate the effect of composition poly(D,L-lactide-co-glycolide)/poly(ε- caprolactone)(PLGA/PCL)blending on the morphology,shrinkage and degradation behaviors of the electrospun fi...The purpose of this study is to investigate the effect of composition poly(D,L-lactide-co-glycolide)/poly(ε- caprolactone)(PLGA/PCL)blending on the morphology,shrinkage and degradation behaviors of the electrospun fibers. With the increase of PLGA content in the composite fibers,the average diameter of the electrospun fibers increased from 1.35μm to 1.95μm.The serious shrinking of the electrospun PLGA meshes could be circumvented by adding 20% PCL in the fibers,resulting from the semi-crystalline nature ...展开更多
The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds wi...The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials(Ca-P bioceramics),which is expected to present a controllable biodegradation rate for patients who need bone regeneration.Physicochemical properties,porosity,compressive strength and degradation properties of the scaffolds were studied.3D printed Ca-P scaffold(3DS),gas foaming Ca-P scaffold(FS)and autogenous bone(AB)were used in vivo for personalized beagle skull defect repair.Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues.FS showed obvious newly formed bone tissues.AB showed the best repair effect,but it was found that AB scaffolds were partially absorbed and degraded.This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.展开更多
In today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens are preserved for fut...In today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens are preserved for future gross examination and/or teaching. Using histological examination of specimens from museum jars from the Pathology Department at the Indiana University School of Medicine, the sequential and chronological degradation of DNA and RNA has been studied. We examined gross specimens from 1920 to 2000. We evaluated histologic preservation of kidney, liver, heart, lung, spleen, uterus and brain for nuclear structure in these samples. Nuclear preservation was based on amount of nuclei per microscopic field and the crispness of the nuclear membrane and internal features. The nuclei in high lipid tissues such as the brain were found to degrade at a quicker rate than dense tissues such as the heart and uterus. Our study has shown that specimens preserved beyond fifty years were likely to have little to no nuclei left, thus indicating that there was little to no DNA and RNA remaining. This technique of histologic evaluation is an important finding and a general guideline which may save research institutions from the expensive process of DNA and RNA extraction.展开更多
Obudu Cattle Ranch covers an area of 2400 hactares at an altitude of 900 - 1500 m above mean sea level and is suitable for cultivation of cucumber (Cucumis sativus), tomato (Solanum lycopersicum), Irish potato (Solanu...Obudu Cattle Ranch covers an area of 2400 hactares at an altitude of 900 - 1500 m above mean sea level and is suitable for cultivation of cucumber (Cucumis sativus), tomato (Solanum lycopersicum), Irish potato (Solanum tuberosum), spinach (Spinacia oleracea) cabbage (Brassica oleracea), lettuce (Lactuca sativa) because of its semitemperate climate. Physicochemical characteristics, degradation rates and vulnerability potential of the soils were studied. Eighteen composite soil samples (0 - 15 and 15 - 30 cm) were collected at interval of 500 m along North-South and East-West transects in nine locations. The soils were characterized as follows: texture of sandy loam for the surface and subsurface soils;pH(H2O) (4.7 - 5.7), organic carbon (4.9 - 74.8 gkg-1), total nitrogen (0.2 - 4.8 gkg-1), carbon-nitrogen ratio (14 - 25), available P (6.66 - 107.89 mgkg-1), effective cation exchange capacity (ECEC) (5.58 - 14.62 cmol·kg-1) and base saturation (49.37% - 85.28%);the surface soils were generally higher in organic carbon, total nitrogen, available P and ECEC than the subsurface. The Soil Degradation Rate (SDR)/ Vulnerability Potential (Vp) weighted values of texture (3/3), soil pH(H2O) (4/2), organic carbon (1/5) and base saturation (2/4) showed moderate to low susceptibility of the soils to degradation or vulnerability. The soils could be managed by liming, practicing crop rotation and using soil conservative measures.展开更多
The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals.Four castrated healthy animals,two rams and two bucks,were used.Animals were daily orally ...The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals.Four castrated healthy animals,two rams and two bucks,were used.Animals were daily orally dosed for 2 weeks with 1 g of each of the following terpenes,α-pinene,limonene andβ-caryophyllene.At the end of each week,rumen fluid(RF)samples were assayed in vitro for their potential to degrade terpenes over time.For each animal,a 10 mL reaction medium(RM)at a ratio 1:9(v/v)was prepared and a terpenes solution at a concentration of 100μg/ml each,was added in each RM tube.Tubes were incubated at 39℃ under anaerobic conditions and their contents sampled at 0,2,4,8,21 and 24 h.RF could degrade terpenes as it was shown by the significantly(P<0.05)higher overall degradation rates.Individual terpene degradation rates,were significantly(P<0.05)higher in week 5 for limonene and marginally(P=0.083)higher also in week 5 forα-pinene.In conclusion,the findings of the present preliminary study suggest that terpenes can be degraded in the rumen fluid.展开更多
The current concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were determined in soils contaminated with Chinese technical product sodium pentachlorophenate(Na-PCP). The estimated half-lif...The current concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were determined in soils contaminated with Chinese technical product sodium pentachlorophenate(Na-PCP). The estimated half-life of octachlorodioxin(OCDD) was about 14 years in contaminated soils based on the local historical record and mass balance calculation during the past 43 years(1960—2003). The isomer profiles remained the same regardless of paddy field soil or riverbank soil. The results indicated that the congener-specific information was efficient in estimating the PCDD/Fs fate in contaminated soils.展开更多
A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydr...A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydrothermal conversion and ion exchange reactions to produce sodium and calcium titanate coatings.SEM confirmed the characteristic nanoporous structure of sodium and calcium titanate,with thicknesses ranging from ca.0.8 to 1.4μm.XPS analysis confirmed the presence of Ti^(4+)-O,Na-O,and Ca-O bonding,whilst Raman spectroscopy demonstrated characteristic vibrational modes(such as TiO 6 octahedral vibrations)of the sodium and calcium titanate perovskite structure.Furthermore,corrosion studies through potentiodynamic polarisation measurements demonstrated the NB/NH CaTC samples to be superior in reducing Mg degradation,compared to other samples tested,through an increase in E_(corr)from-1.49 to-1.33 V,and the reduction in corrosion current density,i corr,from 0.31 to 0.06 mA/cm^(2)for Mg and NB/NH CaTC samples,respectively.There was a clear trend noted for the NB/NH samples,which showed an increase in E corr to more positive values in the following order:Mg<Ti coated<NaTC<CaTC.These nanoporous titanate coatings have potential to be applied onto degradable plates for bone fracture fixation,or other orthopaedic applications.展开更多
Degradation rate of feed proteins in rumen is a basic indicator of new intestinal protein system of ruminants. In this paper, determination methods of degradation rate in rumen including in-vivo method, nylon bag meth...Degradation rate of feed proteins in rumen is a basic indicator of new intestinal protein system of ruminants. In this paper, determination methods of degradation rate in rumen including in-vivo method, nylon bag method and artificial rumen method are compared in order to provide a reference for animal nutrition.展开更多
The in vitro degradation rate of polyanhydride (poly(sebacic acid), diacetoxy terminated), also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding dev...The in vitro degradation rate of polyanhydride (poly(sebacic acid), diacetoxy terminated), also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline (PBS) for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy (SEM). The experimental results showed that PSADT exhibited surface erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.展开更多
Structural and thermodynamic parameters of 16 chloro-phenol compounds in water solution were calculated and fully optimized by using Onsager model in self-consistent reaction field(SCRF) based on the B3LYP/6-311G** le...Structural and thermodynamic parameters of 16 chloro-phenol compounds in water solution were calculated and fully optimized by using Onsager model in self-consistent reaction field(SCRF) based on the B3LYP/6-311G** level.These quantum chemical parameters were used as theoretical descriptors to correlate with the experimental biodegradation rate constant(Kb) of 16 compounds by stepwise multiple linear regression.As a result,a three-parameter model including molecular average polarizability(α),entropy(Sθ),and molar heat capacity at constant volume(CVθ) were established for Kb prediction,which was proposed with correlation coefficient R2 = 0.894.α exhibits the most significant effect on Kb.Variance analysis and standard t-value test were applied to validate the model.As expected,this model exhibits good robustness and prediction ability,which can be used in Kb prediction of analogs.展开更多
The relationship between chemical structures and biodegradation rates (k b) of 22 polycyclic aromatic hydrocarbons (PAHs) was studied using density functional theory (DFT) and stepwise multiple linear regression analy...The relationship between chemical structures and biodegradation rates (k b) of 22 polycyclic aromatic hydrocarbons (PAHs) was studied using density functional theory (DFT) and stepwise multiple linear regression analysis (SMLR) method.The equilibrium geometries and vibration frequency have been investigated at the B3LYP/6-31+G(d,p) level by thinking Solvent effects using a selfconsistent reaction field (SCRF) based on the polarizable continuum model (PCM).It was concluded that the biodegradation rate was closely related to its molecular structure,and there is one high correlation coefficient between the in-plane bending vibration frequency of the conjugated ring of PAHs (Freq) and k b.By means of regression analysis,the main factors affecting the biodegradation rate were obtained and the equation of quantitative structure-activity relationship (QSAR) was successfully established kb =-0.653+0.001Freq+0.068CQ+0.049N1.Statistical evaluation of the developed QSAR showed that the relationships were statistically significant and the model had good predictive ability.The fact that a bending frequency is more important than the HOMO or LUMO energies in predicting k b suggests that the bending of benzene ring might play an important role in the enzymatic catalysis of the initial oxidation step.展开更多
The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environm...The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environment,the hot-extruded fine-grained Mg-Zn-Y-Nd alloy microtubes,which are employed to manufacture vascular stents,were tested under radial compressive stress in the dynamic Hanks'Balanced Salt Solution(HBSS).The results revealed that the high flow rate accelerates the degradation of Mg alloy microtubes and its degradation is sensitive to radial compressive stress.These results contribute to understanding the service performance of Mg alloys as vascular stent materials.展开更多
Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading fau...Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading faults is no longer appropriate.A cascading fault analysis method considering multi-energy coupling characteristics is of vital importance.In this study,an innovative analysis method for cascading faults in integrated heat and electricity systems(IHES)is proposed.It considers the degradation characteristics of transmission and energy supply com-ponents in the system to address the impact of component aging on cascading faults.Firstly,degradation models for the current carrying capacity of transmission lines,the water carrying capacity and insulation performance of thermal pipelines,as well as the performance of energy supply equipment during aging,are developed.Secondly,a simulation process for cascading faults in the IHES is proposed.It utilizes an overload-dominated development model to predict the propagation path of cascading faults while also considering network islanding,electric-heating rescheduling,and load shedding.The propagation of cascading faults is reflected in the form of fault chains.Finally,the results of cascading faults under different aging levels are analyzed through numerical examples,thereby verifying the effectiveness and rationality of the proposed model and method.展开更多
Degradability of bone tissue engineering scaffold that matching the regeneration rate could allow a complete replacement of host tissue.However,the porous structure of biodegradable Mg scaffolds certainly generated hi...Degradability of bone tissue engineering scaffold that matching the regeneration rate could allow a complete replacement of host tissue.However,the porous structure of biodegradable Mg scaffolds certainly generated high specific surface area,and the three-dimensional interconnected pores provided fast pervasive invasion entrance for the corrosive medium,rising concern of the structural integrity during the degradation.To clarify the structural evolution of the three-dimensional(3D)porous structure,semi-static immersion tests were carried out to evaluate the degradation performance in our previous study.Nevertheless,dynamic immersion tests mimicking the in vivo circulatory fluid through the interconnected porous structure have yet been investigated.Moreover,the effects of dynamic flow rates on the degradation deposition behavior of 3D porous Mg scaffolds were rarely reported.In this study,Mg scaffolds degraded at three flow rates exhibited different degradation rates and deposition process.A flow rate of 0.5 m L/min introduced maximum drop of porosity by accumulated deposition products.The deposition products provided limited protection against the degradation process at a flow rate of 1.0 m L/min.The three-dimensional interconnected porous structure of Mg scaffold degraded at 2.0 m L/min well retained after 14 days showing the best interconnectivity resistance to the degradation deposition process.The dynamic immersion tests disclosed the reason for the different degradation rates on account of flow rates,which may bring insight into understanding of varied in vivo degradation rates related to implantation sites.展开更多
Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have...Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have become major bottlenecks for marvelous photocatalytic performance of photocatalysts.Herein, to address these issue, Nanodiamonds/yolk-shell ZnFe_(2)O_(4) spheres(NDs/ZFO) nanocomposites were successfully constructed via a facile two-step of solvothermal and calcination methods. The synthesized optimal NDs/ZFO-10 nanocomposite exhibits superior photocatalytic degradation activity of antibiotic under visible light, approximately 85% of the total tetracycline(TC) is degraded, and this photocatalyst shows durable cycling stability. This stems from two aspects of refinement: improvement of light absorption capacity and photo-induced charges migration and separation. In addition, the NDs/ZFO composite photocatalyst features excellent magnetic recovery capability, facilitating the recovery of photocatalyst in industry. This study opens a new chapter in the combination of NDs with magnetic materials, and deepens the understanding of the application of NDs modified composite photocatalysts.展开更多
Four-dimensional(4D)printing is a promising technology that provides solutions for compelling needs in various fields.Most of the reported 4D printed systems are based on the temporal shape transformation of printed s...Four-dimensional(4D)printing is a promising technology that provides solutions for compelling needs in various fields.Most of the reported 4D printed systems are based on the temporal shape transformation of printed subjects.Induction of temporal heterogenicity in functions in addition to shape may extend the scope of 4D printing.Herein,we report a 4D printing approach using plant protein(zein)gel inspired by the amyloid fibrils formation mechanism.The printing of zein gel in a specialized layered-Carbopol supporting bath with different water concentrations in an ethanol-water mixture modulates hydrophobic and hydrogen bonding that causes temporal changes in functions.The part of the construct printed in a supporting bath with higher water content exhibits higher drug loading,faster drug release and degradation than those printed in the supporting bath with lower water content.Tri-segment conduit and butterfly-shaped construct with two asymmetrical wings are printed using this system to evaluate biomedical function as nerve conduit and drug delivery system.4D printed conduits are also effective as a drug-eluting urethral stent in the porcine model.Overall,this study extends the concept of 4D printing beyond shape transformation and presents an approach of fabricating specialized baths for 4D printing that can also be extended to other materials to obtain 4D printed medical devices with translational potential.展开更多
This paper is intended to explore soil organic matter and carbon isotope fractionation at three locations of the Passaic River to determine if microbial degradation of organic contaminants in soil is correlated to the...This paper is intended to explore soil organic matter and carbon isotope fractionation at three locations of the Passaic River to determine if microbial degradation of organic contaminants in soil is correlated to the surrounding physical environment. Microbial degradation of organic contaminants is important for the detoxification of toxic substances thereby minimizing stagnation in the environment and accumulating in the food chain. Since organic contaminants are not easily dissolved in water, they will penetrate sediment and end up enriching the adjacent soil. The hypothesis that we are testing is microbial activity and carbon isotope fractionation will be greater in preserved soils than urban soils. The reason why this is expected to be the case is the expectation of higher microbial activity in preserved environments due to less exposure to pollutants, better soil structure, higher organic matter content, and more favorable conditions for microbial growth. This is contrasted with urban soils, which are impacted by pollutants and disturbances, potentially inhibiting microbial activity. We wish to collect soil samples adjacent to the Passaic River at a pristine location, Great Swamp Wildlife Refuge, a suburban location, Goffle Brook Park, Hawthorne NJ, and an urban location, Paterson NJ. These soil samples will be weighed for soil organic matter (SOM) and weighed for isotope ratio mass spectrometry (IRMS) to test organic carbon isotopes. High SOM and δ13C depletion activity indicate microbial growth based on the characteristics of the soil horizon rather than the location of the soil sample which results in degradation of organic compounds.展开更多
Pulse rate is one of the important characteristics of traditional Chinese medicine pulse diagnosis,and it is of great significance for determining the nature of cold and heat in diseases.The prediction of pulse rate b...Pulse rate is one of the important characteristics of traditional Chinese medicine pulse diagnosis,and it is of great significance for determining the nature of cold and heat in diseases.The prediction of pulse rate based on facial video is an exciting research field for getting palpation information by observation diagnosis.However,most studies focus on optimizing the algorithm based on a small sample of participants without systematically investigating multiple influencing factors.A total of 209 participants and 2,435 facial videos,based on our self-constructed Multi-Scene Sign Dataset and the public datasets,were used to perform a multi-level and multi-factor comprehensive comparison.The effects of different datasets,blood volume pulse signal extraction algorithms,region of interests,time windows,color spaces,pulse rate calculation methods,and video recording scenes were analyzed.Furthermore,we proposed a blood volume pulse signal quality optimization strategy based on the inverse Fourier transform and an improvement strategy for pulse rate estimation based on signal-to-noise ratio threshold sliding.We found that the effects of video estimation of pulse rate in the Multi-Scene Sign Dataset and Pulse Rate Detection Dataset were better than in other datasets.Compared with Fast independent component analysis and Single Channel algorithms,chrominance-based method and plane-orthogonal-to-skin algorithms have a more vital anti-interference ability and higher robustness.The performances of the five-organs fusion area and the full-face area were better than that of single sub-regions,and the fewer motion artifacts and better lighting can improve the precision of pulse rate estimation.展开更多
基金This work is financially supported by the National Key Research and Development Program of China(Grant No.2016YFB0301100)the Chongqing Foundation and Advanced Research Project(Grant No.cstc2019jcyj-zdxmX0010)+1 种基金the Natural Science Foundation Commission of China(Grant No.51571044 and 51874062)Fundamental Research Funds for the Central Universities(Grant No.2018CDGFCL0005 and 2019CDXYCL0031).
文摘In this work,as-cast Mg-Ni-Y alloys were proposed to develop a feasible material for fracturing balls,and their mechanical performance and corrosion behavior were systematically investigated.Long period stacking order(LPSO)phase was firstly introduced to improve both the mechanical properties and degradation rate of magnesium alloys.With the increase of LPSO phase,the compressive strength was improved significantly,while the elongation of the alloys decreased owing to the relatively brittle nature of LPSO phase.Due to the higher corrosion potential of LPSO phase,the LPSO phase can accelerate the corrosion process by providing more micro-couples.However,the LPSO phase would serve as the corrosion barrier between the corrosion medium and the matrix when the contents of LPSO phase are too high in Mg92.5Ni3Y4.5 and Mg87.5Ni5Y7.5 alloys.As-cast Mg97.5Ni1Y1.5 alloy with satisfactory mechanical properties and rapid degradation rate was successfully developed,exhibiting a high degradation rate of 6675 mm/a(93℃)in 3 wt.%KCl solution and a favorable ultimate compressive strength of 410 MPa.The degradation rate of Mg97.5Ni1Y1.5 alloy is 2-5 times of the current commercial magnesium alloy fracturing materials.
文摘The apparent degradation rate constant of fluticasone propionate(FLT) in 0.1 M NaOH:methanol=1:1 at 37 °C was previously reported to be 0.169 ± 0.003 h^(-1), and four degradation products(products 1–4) were observed in the solution. The aims of the present study were to assess the degradation rates of FLT in other alkaline solutions and clarify the chemical structures of the four degradation products in order to obtain basic data for designing an enema for inflammatory bowel disease. The apparent degradation rate constants in 0.05 M NaOH and 0.1 M NaOH:CH_3CN=1:1 were 0.472 ± 0.013 h^(-1) and 0.154 ± 0.000 h^(-1)(n=3), respectively. The chemical structures of products 1–4 in 0.1 M NaOH:methanol=1:1 were revealed by nuclear magnetic resonance(NMR)and mass spectrometry data. The chemical structure of products 2 was that the 17-position of the thioester moiety of FLT was substituted by a carboxylic acid. The degradation product in 0.1 M NaOH:CH_3CN=1:1 was found to be product 2 based on ~1H NMR data. The degradation product in 0.05 M NaOH was considered to be product 2 based on the retention time of HPLC. These results are useful for detecting the degradation products of FLT by enzymes of the intestinal bacterial flora in the large intestine after dosing FLT as an enema.
基金This work was financially supported by the National Natural Science Foundation of China(No. 20304013)partially by Natural Science Foundation of Zhejiang Province(No.Y405029).
文摘The purpose of this study is to investigate the effect of composition poly(D,L-lactide-co-glycolide)/poly(ε- caprolactone)(PLGA/PCL)blending on the morphology,shrinkage and degradation behaviors of the electrospun fibers. With the increase of PLGA content in the composite fibers,the average diameter of the electrospun fibers increased from 1.35μm to 1.95μm.The serious shrinking of the electrospun PLGA meshes could be circumvented by adding 20% PCL in the fibers,resulting from the semi-crystalline nature ...
基金This work was supported by the National Key Research and Development Program of China(No.18YFB1105600,2018YFC1106800)National Natural Science Foundation of China(51875518)+1 种基金Sichuan Province Science&Technology Department Projects(2016CZYD0004,2017SZ0001,2018GZ0142,2019YFH0079)Research Foundation for Young Teachers of Sichuan University(2018SCUH0017)and The“111”Project(No.B16033).
文摘The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials(Ca-P bioceramics),which is expected to present a controllable biodegradation rate for patients who need bone regeneration.Physicochemical properties,porosity,compressive strength and degradation properties of the scaffolds were studied.3D printed Ca-P scaffold(3DS),gas foaming Ca-P scaffold(FS)and autogenous bone(AB)were used in vivo for personalized beagle skull defect repair.Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues.FS showed obvious newly formed bone tissues.AB showed the best repair effect,but it was found that AB scaffolds were partially absorbed and degraded.This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.
文摘In today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens are preserved for future gross examination and/or teaching. Using histological examination of specimens from museum jars from the Pathology Department at the Indiana University School of Medicine, the sequential and chronological degradation of DNA and RNA has been studied. We examined gross specimens from 1920 to 2000. We evaluated histologic preservation of kidney, liver, heart, lung, spleen, uterus and brain for nuclear structure in these samples. Nuclear preservation was based on amount of nuclei per microscopic field and the crispness of the nuclear membrane and internal features. The nuclei in high lipid tissues such as the brain were found to degrade at a quicker rate than dense tissues such as the heart and uterus. Our study has shown that specimens preserved beyond fifty years were likely to have little to no nuclei left, thus indicating that there was little to no DNA and RNA remaining. This technique of histologic evaluation is an important finding and a general guideline which may save research institutions from the expensive process of DNA and RNA extraction.
文摘Obudu Cattle Ranch covers an area of 2400 hactares at an altitude of 900 - 1500 m above mean sea level and is suitable for cultivation of cucumber (Cucumis sativus), tomato (Solanum lycopersicum), Irish potato (Solanum tuberosum), spinach (Spinacia oleracea) cabbage (Brassica oleracea), lettuce (Lactuca sativa) because of its semitemperate climate. Physicochemical characteristics, degradation rates and vulnerability potential of the soils were studied. Eighteen composite soil samples (0 - 15 and 15 - 30 cm) were collected at interval of 500 m along North-South and East-West transects in nine locations. The soils were characterized as follows: texture of sandy loam for the surface and subsurface soils;pH(H2O) (4.7 - 5.7), organic carbon (4.9 - 74.8 gkg-1), total nitrogen (0.2 - 4.8 gkg-1), carbon-nitrogen ratio (14 - 25), available P (6.66 - 107.89 mgkg-1), effective cation exchange capacity (ECEC) (5.58 - 14.62 cmol·kg-1) and base saturation (49.37% - 85.28%);the surface soils were generally higher in organic carbon, total nitrogen, available P and ECEC than the subsurface. The Soil Degradation Rate (SDR)/ Vulnerability Potential (Vp) weighted values of texture (3/3), soil pH(H2O) (4/2), organic carbon (1/5) and base saturation (2/4) showed moderate to low susceptibility of the soils to degradation or vulnerability. The soils could be managed by liming, practicing crop rotation and using soil conservative measures.
文摘The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals.Four castrated healthy animals,two rams and two bucks,were used.Animals were daily orally dosed for 2 weeks with 1 g of each of the following terpenes,α-pinene,limonene andβ-caryophyllene.At the end of each week,rumen fluid(RF)samples were assayed in vitro for their potential to degrade terpenes over time.For each animal,a 10 mL reaction medium(RM)at a ratio 1:9(v/v)was prepared and a terpenes solution at a concentration of 100μg/ml each,was added in each RM tube.Tubes were incubated at 39℃ under anaerobic conditions and their contents sampled at 0,2,4,8,21 and 24 h.RF could degrade terpenes as it was shown by the significantly(P<0.05)higher overall degradation rates.Individual terpene degradation rates,were significantly(P<0.05)higher in week 5 for limonene and marginally(P=0.083)higher also in week 5 forα-pinene.In conclusion,the findings of the present preliminary study suggest that terpenes can be degraded in the rumen fluid.
文摘The current concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were determined in soils contaminated with Chinese technical product sodium pentachlorophenate(Na-PCP). The estimated half-life of octachlorodioxin(OCDD) was about 14 years in contaminated soils based on the local historical record and mass balance calculation during the past 43 years(1960—2003). The isomer profiles remained the same regardless of paddy field soil or riverbank soil. The results indicated that the congener-specific information was efficient in estimating the PCDD/Fs fate in contaminated soils.
基金This work was supported by the Engineering and Physi-cal Sciences Research Council[grant numbers EP/K029592/1,EP/L022494/1].
文摘A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydrothermal conversion and ion exchange reactions to produce sodium and calcium titanate coatings.SEM confirmed the characteristic nanoporous structure of sodium and calcium titanate,with thicknesses ranging from ca.0.8 to 1.4μm.XPS analysis confirmed the presence of Ti^(4+)-O,Na-O,and Ca-O bonding,whilst Raman spectroscopy demonstrated characteristic vibrational modes(such as TiO 6 octahedral vibrations)of the sodium and calcium titanate perovskite structure.Furthermore,corrosion studies through potentiodynamic polarisation measurements demonstrated the NB/NH CaTC samples to be superior in reducing Mg degradation,compared to other samples tested,through an increase in E_(corr)from-1.49 to-1.33 V,and the reduction in corrosion current density,i corr,from 0.31 to 0.06 mA/cm^(2)for Mg and NB/NH CaTC samples,respectively.There was a clear trend noted for the NB/NH samples,which showed an increase in E corr to more positive values in the following order:Mg<Ti coated<NaTC<CaTC.These nanoporous titanate coatings have potential to be applied onto degradable plates for bone fracture fixation,or other orthopaedic applications.
文摘Degradation rate of feed proteins in rumen is a basic indicator of new intestinal protein system of ruminants. In this paper, determination methods of degradation rate in rumen including in-vivo method, nylon bag method and artificial rumen method are compared in order to provide a reference for animal nutrition.
基金Funded by the China Scholarship Council and Wisconsin Institute for Discovery(WID)the Scientific Research Staring Foundation,Fujian University of Technology,China(No.GY-Z13028)+1 种基金the Programfor New Century Excellent Talents in Fujian Province University(NCETFJ-2010)the Research Fund for Fujian Provincial University(JK-2010038)
文摘The in vitro degradation rate of polyanhydride (poly(sebacic acid), diacetoxy terminated), also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline (PBS) for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy (SEM). The experimental results showed that PSADT exhibited surface erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.
基金Supported by the State Key Program of NNSFC (No. 20737001)NNSFC (No. 20977044)
文摘Structural and thermodynamic parameters of 16 chloro-phenol compounds in water solution were calculated and fully optimized by using Onsager model in self-consistent reaction field(SCRF) based on the B3LYP/6-311G** level.These quantum chemical parameters were used as theoretical descriptors to correlate with the experimental biodegradation rate constant(Kb) of 16 compounds by stepwise multiple linear regression.As a result,a three-parameter model including molecular average polarizability(α),entropy(Sθ),and molar heat capacity at constant volume(CVθ) were established for Kb prediction,which was proposed with correlation coefficient R2 = 0.894.α exhibits the most significant effect on Kb.Variance analysis and standard t-value test were applied to validate the model.As expected,this model exhibits good robustness and prediction ability,which can be used in Kb prediction of analogs.
基金supported by the National Natural Science Foundation of China (No. 40976041,20775074)
文摘The relationship between chemical structures and biodegradation rates (k b) of 22 polycyclic aromatic hydrocarbons (PAHs) was studied using density functional theory (DFT) and stepwise multiple linear regression analysis (SMLR) method.The equilibrium geometries and vibration frequency have been investigated at the B3LYP/6-31+G(d,p) level by thinking Solvent effects using a selfconsistent reaction field (SCRF) based on the polarizable continuum model (PCM).It was concluded that the biodegradation rate was closely related to its molecular structure,and there is one high correlation coefficient between the in-plane bending vibration frequency of the conjugated ring of PAHs (Freq) and k b.By means of regression analysis,the main factors affecting the biodegradation rate were obtained and the equation of quantitative structure-activity relationship (QSAR) was successfully established kb =-0.653+0.001Freq+0.068CQ+0.049N1.Statistical evaluation of the developed QSAR showed that the relationships were statistically significant and the model had good predictive ability.The fact that a bending frequency is more important than the HOMO or LUMO energies in predicting k b suggests that the bending of benzene ring might play an important role in the enzymatic catalysis of the initial oxidation step.
基金the financial support of the National Key Research and Development Program of China(2018YFC1106703)the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U1804251)。
文摘The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environment,the hot-extruded fine-grained Mg-Zn-Y-Nd alloy microtubes,which are employed to manufacture vascular stents,were tested under radial compressive stress in the dynamic Hanks'Balanced Salt Solution(HBSS).The results revealed that the high flow rate accelerates the degradation of Mg alloy microtubes and its degradation is sensitive to radial compressive stress.These results contribute to understanding the service performance of Mg alloys as vascular stent materials.
基金supported by Shanghai Rising-Star Program(No.22QA1403900)the National Natural Science Foundation of China(No.71804106)the Noncarbon Energy Conversion and Utilization Institute under the Shanghai Class IV Peak Disciplinary Development Program.
文摘Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading faults is no longer appropriate.A cascading fault analysis method considering multi-energy coupling characteristics is of vital importance.In this study,an innovative analysis method for cascading faults in integrated heat and electricity systems(IHES)is proposed.It considers the degradation characteristics of transmission and energy supply com-ponents in the system to address the impact of component aging on cascading faults.Firstly,degradation models for the current carrying capacity of transmission lines,the water carrying capacity and insulation performance of thermal pipelines,as well as the performance of energy supply equipment during aging,are developed.Secondly,a simulation process for cascading faults in the IHES is proposed.It utilizes an overload-dominated development model to predict the propagation path of cascading faults while also considering network islanding,electric-heating rescheduling,and load shedding.The propagation of cascading faults is reflected in the form of fault chains.Finally,the results of cascading faults under different aging levels are analyzed through numerical examples,thereby verifying the effectiveness and rationality of the proposed model and method.
基金supported by grants from National&Local Joint Engineering Research Center of Orthopaedic Biomaterials(XMHT20190204007)Shenzhen Key Medical Discipline Construction Fund(No.SZXK023)+4 种基金Shenzhen“San-Ming”Project of Medicine(No.SZSM201612092)Shenzhen Research and Development Project(No.Z2021N054)Guangdong Basic and Applied Basic Research Foundations(No.2019A1515011290,2021A1515012586,2019A1515110983)China Postdoctoral Science Foundation(No.2020M672756)Bethune Charitable Foundation and CSPC Osteoporosis Research Project(No.G-X-2020–1107–21)。
文摘Degradability of bone tissue engineering scaffold that matching the regeneration rate could allow a complete replacement of host tissue.However,the porous structure of biodegradable Mg scaffolds certainly generated high specific surface area,and the three-dimensional interconnected pores provided fast pervasive invasion entrance for the corrosive medium,rising concern of the structural integrity during the degradation.To clarify the structural evolution of the three-dimensional(3D)porous structure,semi-static immersion tests were carried out to evaluate the degradation performance in our previous study.Nevertheless,dynamic immersion tests mimicking the in vivo circulatory fluid through the interconnected porous structure have yet been investigated.Moreover,the effects of dynamic flow rates on the degradation deposition behavior of 3D porous Mg scaffolds were rarely reported.In this study,Mg scaffolds degraded at three flow rates exhibited different degradation rates and deposition process.A flow rate of 0.5 m L/min introduced maximum drop of porosity by accumulated deposition products.The deposition products provided limited protection against the degradation process at a flow rate of 1.0 m L/min.The three-dimensional interconnected porous structure of Mg scaffold degraded at 2.0 m L/min well retained after 14 days showing the best interconnectivity resistance to the degradation deposition process.The dynamic immersion tests disclosed the reason for the different degradation rates on account of flow rates,which may bring insight into understanding of varied in vivo degradation rates related to implantation sites.
基金the founding support from the National Natural Science Foundation of China(21906072 and 22006057)the Natural Science Foundation of Jiangsu Province(BK20190982)+2 种基金Henan Postdoctoral Foundation(202003013)“Doctor of Mass entrepreneurship and innovation” Project in Jiangsu ProvinceOpen Fund for Hebei Province Key Laboratory of Sustained Utilization & Development of Water Recourse(HSZYL2021003)。
文摘Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have become major bottlenecks for marvelous photocatalytic performance of photocatalysts.Herein, to address these issue, Nanodiamonds/yolk-shell ZnFe_(2)O_(4) spheres(NDs/ZFO) nanocomposites were successfully constructed via a facile two-step of solvothermal and calcination methods. The synthesized optimal NDs/ZFO-10 nanocomposite exhibits superior photocatalytic degradation activity of antibiotic under visible light, approximately 85% of the total tetracycline(TC) is degraded, and this photocatalyst shows durable cycling stability. This stems from two aspects of refinement: improvement of light absorption capacity and photo-induced charges migration and separation. In addition, the NDs/ZFO composite photocatalyst features excellent magnetic recovery capability, facilitating the recovery of photocatalyst in industry. This study opens a new chapter in the combination of NDs with magnetic materials, and deepens the understanding of the application of NDs modified composite photocatalysts.
基金This study was supported by the National Key R&D Program of China(2019YFE0101200)the Science and Technology Commission Shanghai Municipality,China(13JC1403400,18490740200)+1 种基金the Foreign Young Talent Program from the Ministry of Science and Technology,China(QN2022134003L)the Plan of Jiaxing Innovation and Elites Leading,China.
文摘Four-dimensional(4D)printing is a promising technology that provides solutions for compelling needs in various fields.Most of the reported 4D printed systems are based on the temporal shape transformation of printed subjects.Induction of temporal heterogenicity in functions in addition to shape may extend the scope of 4D printing.Herein,we report a 4D printing approach using plant protein(zein)gel inspired by the amyloid fibrils formation mechanism.The printing of zein gel in a specialized layered-Carbopol supporting bath with different water concentrations in an ethanol-water mixture modulates hydrophobic and hydrogen bonding that causes temporal changes in functions.The part of the construct printed in a supporting bath with higher water content exhibits higher drug loading,faster drug release and degradation than those printed in the supporting bath with lower water content.Tri-segment conduit and butterfly-shaped construct with two asymmetrical wings are printed using this system to evaluate biomedical function as nerve conduit and drug delivery system.4D printed conduits are also effective as a drug-eluting urethral stent in the porcine model.Overall,this study extends the concept of 4D printing beyond shape transformation and presents an approach of fabricating specialized baths for 4D printing that can also be extended to other materials to obtain 4D printed medical devices with translational potential.
文摘This paper is intended to explore soil organic matter and carbon isotope fractionation at three locations of the Passaic River to determine if microbial degradation of organic contaminants in soil is correlated to the surrounding physical environment. Microbial degradation of organic contaminants is important for the detoxification of toxic substances thereby minimizing stagnation in the environment and accumulating in the food chain. Since organic contaminants are not easily dissolved in water, they will penetrate sediment and end up enriching the adjacent soil. The hypothesis that we are testing is microbial activity and carbon isotope fractionation will be greater in preserved soils than urban soils. The reason why this is expected to be the case is the expectation of higher microbial activity in preserved environments due to less exposure to pollutants, better soil structure, higher organic matter content, and more favorable conditions for microbial growth. This is contrasted with urban soils, which are impacted by pollutants and disturbances, potentially inhibiting microbial activity. We wish to collect soil samples adjacent to the Passaic River at a pristine location, Great Swamp Wildlife Refuge, a suburban location, Goffle Brook Park, Hawthorne NJ, and an urban location, Paterson NJ. These soil samples will be weighed for soil organic matter (SOM) and weighed for isotope ratio mass spectrometry (IRMS) to test organic carbon isotopes. High SOM and δ13C depletion activity indicate microbial growth based on the characteristics of the soil horizon rather than the location of the soil sample which results in degradation of organic compounds.
基金supported by the Key Research Program of the Chinese Academy of Sciences(grant number ZDRW-ZS-2021-1-2).
文摘Pulse rate is one of the important characteristics of traditional Chinese medicine pulse diagnosis,and it is of great significance for determining the nature of cold and heat in diseases.The prediction of pulse rate based on facial video is an exciting research field for getting palpation information by observation diagnosis.However,most studies focus on optimizing the algorithm based on a small sample of participants without systematically investigating multiple influencing factors.A total of 209 participants and 2,435 facial videos,based on our self-constructed Multi-Scene Sign Dataset and the public datasets,were used to perform a multi-level and multi-factor comprehensive comparison.The effects of different datasets,blood volume pulse signal extraction algorithms,region of interests,time windows,color spaces,pulse rate calculation methods,and video recording scenes were analyzed.Furthermore,we proposed a blood volume pulse signal quality optimization strategy based on the inverse Fourier transform and an improvement strategy for pulse rate estimation based on signal-to-noise ratio threshold sliding.We found that the effects of video estimation of pulse rate in the Multi-Scene Sign Dataset and Pulse Rate Detection Dataset were better than in other datasets.Compared with Fast independent component analysis and Single Channel algorithms,chrominance-based method and plane-orthogonal-to-skin algorithms have a more vital anti-interference ability and higher robustness.The performances of the five-organs fusion area and the full-face area were better than that of single sub-regions,and the fewer motion artifacts and better lighting can improve the precision of pulse rate estimation.
