Introduction: 68Ga-PSMA-11 is considered the gold standard in detection of micro and oligometastases in advanced prostate cancer, being used for therapeutic planning, as well as, potentially, for evaluating response t...Introduction: 68Ga-PSMA-11 is considered the gold standard in detection of micro and oligometastases in advanced prostate cancer, being used for therapeutic planning, as well as, potentially, for evaluating response to treatment. The development of ready-to-use lyophilized kit of PSMA-11 adds quality and safety to the routine use of this radiopharmaceutical and represents a pharmacotechnical challenge as it must preserve the integrity and specificity of the ligand. Methods: PSMA-11 kit formulation was proposed, considering radiolabeling parameters and the preservation of the peptide during the lyophilization process, using mannitol as an excipient. Critical temperature characterization studies were carried out using DSC equipment and the freeze-drying process was developed. The direct radiolabeling conditions were evaluated and standardized using 68Ge/68Ga generator eluate from two different manufacturers (ITG and Eckert & Ziegler). The radiochemical purity was evaluated by TLC and HPLC. Biological evaluation was carried out with lyophilized PSMA-11 to demonstrate the integrity of the peptide and preservation of biological activity after the lyophilization process. Results: Based on critical temperature characterization studies, the freeze-drying cycle was designed to reach a freezing temperature of around −40˚C and primary drying at 2˚C. Using 20 mg of mannitol, an intact and elegant lyophilized cake was obtained. PSMA-11 lyophilized kit was directly labeled with 68Ga eluate from 68Ge/68Ga GMP generators (ITG and Eckert & Ziegler) resulting in % RP > 95% at pH 4.0 to 4.5. The results obtained from in vitro and in vivo biological competition studies confirmed the preservation of PSMA-11 affinity for the receptor after lyophilization. Conclusion: A lyophilized formulation (Kit) of PSMA-11 was successfully obtained, which preserved the integrity and biological activity of the peptide and guaranteed radiolabeling efficiency.展开更多
To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstru...To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.展开更多
Cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to i...Cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties.This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement mortar.The results show that K-SAP significantly affects the cement mortar’s rheological behavior,with distinct phases of water absorption and release,leading to changes in workability over time.Furthermore,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics.Notably,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage behavior.Moreover,K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP.展开更多
To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cation...To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing conditions.An SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer mortar.Meanwhile,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage coefficient.The experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and time.Finally,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.展开更多
To investigate the freeze-thaw(F-T)damages and failure characteristics of rock mass with arc-shaped joints in cold regions,three types of cement mortar specimens with different central angles and prefabricated arc-sha...To investigate the freeze-thaw(F-T)damages and failure characteristics of rock mass with arc-shaped joints in cold regions,three types of cement mortar specimens with different central angles and prefabricated arc-shaped flaws are subjected to uniaxial compressive tests under different F-T cycles.Experimental observations show that the uniaxial compressive strength of specimens are significantly influenced by F-T cycles and their failure modes are mainly affected by the central angleαof the prefabricated flaws.Unlike the specimens with a central angle of 60°,the specimens with a central angle of 120°and 180°have greater curvature of flaws,so tensile cracks occur in the arc-top area of their prefabricated flaws.According to experimental images observed by environmental scanning electron microscope(ESEM),as the number of F-T cycles increases,the deterioration effect of the specimen becomes more obvious,which is specifically reflected in the increase of the mass loss,peak stress loss,and damage variables as a power function,and the peak strain decreases as a quadratic polynomial.According to numerical results using two-dimensional particle flow code(PFC2D),it is found that F-T cycles cause more damage to the specimen in the early stages than in the later ones.The area of the concentrated compressive stress zone in the middle is decreased due to the increased number of F-T cycles,while the area of the surrounding tensile-shear stress zone is increased.The models appear different failure modes due to the release of concentrated stress in different tensile-shear zones.展开更多
In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion ero...In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.展开更多
Red mud(RM)is a low-activity industrial solid waste,and its utilization as a resource is currently a hot topic.In this study,the micro characteristics of red mud at different calcination temperatures were analyzed usi...Red mud(RM)is a low-activity industrial solid waste,and its utilization as a resource is currently a hot topic.In this study,the micro characteristics of red mud at different calcination temperatures were analyzed using X-ray diffraction and scanning electron microscopy.The performance of calcined red mud was determined through mortar strength tests.Results indicate that high-temperature calcination can change the mineral composition and microstructure of red mud,and increase the surface roughness and specific surface area.At the optimal temperature of 700°C,the addition of calcined red mud still leads to a decrease in mortar strength,but its activity index and flexural coefficient increase by 16.2%and 11.9%with respect to uncalcined red mud,reaching values of 0.826 and 0.974,respectively.Compared with the control group,the synergistic activation of calcined red mud with slag can increase the compressive and flexural strength of the mortar by 12.9%and 1.5%,reaching 8.7 and 62.4 MPa,respectively.Correspondingly,the activity index and flexural coefficient of the calcined RM and GGBS(Ground Granulated Blast furnace Slag)mixtures also increase to 1.015 and 1.130,respectively.展开更多
This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP re...This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.展开更多
Purpose–During the construction process of the China Railway Track System(CRTS)I type filling layer,the nonwoven fabric bags have been used as grouting templates for cement asphalt(CA)emulsified mortar.The porous str...Purpose–During the construction process of the China Railway Track System(CRTS)I type filling layer,the nonwoven fabric bags have been used as grouting templates for cement asphalt(CA)emulsified mortar.The porous structure of nonwoven fabrics endowed the templates with breathability and water permeability.The standard requires that the volume expansion rate of CA mortar must be controlled within 1%–3%,which can generate expansion pressure to ensure that the cavities under track slabs are filled fully.However,the expansion pressure caused some of the water to seep out from the periphery of the filling bag,and it would affect the actual mix proportion of CA mortar.The differences in physical and mechanical properties between the CA mortar under track slabs and the CA mortar formed in the laboratory were studied in this paper.The relevant results could provide important methods for the research of filling layer materials for CRTS I type and other types of ballastless tracks in China.Design/methodology/approach–During the inspection of filling layer,the samples of CA mortar from different working conditions and raw materials were taken by uncovering the track slabs and drilling cores.The physical and mechanical properties of CA mortar under the filling layer of the slab were systematically analyzed by testing the electrical flux,compressive strength and density of mortar in different parts of the filling layer.Findings–In this paper,the electric flux,the physical properties and mechanical properties of different parts of CA mortar under the track slab were investigated.The results showed that the density,electric flux and compressive strength of CA mortar were affected by the composition of raw materials for dry powders and different parts of the filling layer.In addition,the electrical flux of CA mortar gradually decreased within 90 days’age.The electrical flux of samples with the thickness of 54 mm was lower than 500 C.Therefore,the impermeability and durability of CA mortar could be improved by increasing the thickness of filling layer.Besides,the results showed that the compressive strength of CA mortar increased,while the density and electric flux decreased gradually,with the prolongation of hardening time.Originality/value–During 90 days’age,the electrical flux of the CA mortar gradually decreased with the increase of specimen thickness and the electrical flux of the specimens with the thickness of 54 mm was lower than 500 C.The impermeability and durability of the CA mortar could be improved by increasing the thickness of filling layer.The proposed method can provide reference for the further development and improvement of CRTS I and CRTS II type ballastless track in China.展开更多
This study focuses on the effect of ultrafine waste glass powder on cement strength,gas permeability and pore structure.Varying contents were considered,with particle sizes ranging from 2 to 20μm.Moreover,alkali acti...This study focuses on the effect of ultrafine waste glass powder on cement strength,gas permeability and pore structure.Varying contents were considered,with particle sizes ranging from 2 to 20μm.Moreover,alkali activation was considered to ameliorate the reactivity and cementitious properties,which were assessed by using scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),and specific surface area pore size distribution analysis.According to the results,without the addition of alkali activators,the performance of glass powder mortar decreases as the amount of glass powder increases,affecting various aspects such as strength and resistance to gas permeability.Only 5%glass powder mortar demonstrated a compressive strength at 60 days higher than that of the control group.However,adding alkali activator(CaO)during hydration ameliorated the hydration environment,increased the alkalinity of the composite system,activated the reactivity of glass powder,and enhanced the interaction of glass powder and pozzolanic reaction.In general,compared to ordinary cement mortar,alkali-activated glass powder mortar produces more hydration products,showcases elevated density,and exhibits improved gas resistance.Furthermore,alkali-activated glass powder mortar demonstrates an improvement in performance across various aspects as the content increases.At a substitution rate of 15%,the glass powder mortar reaches its optimal levels of strength and resistance to gas permeability,with a compressive strength increase ranging from 28.4%to 34%,and a gas permeation rate reduction between 51.8%and 66.7%.展开更多
The mining process involves drilling and excavation, resulting in the production of waste rock and tailings. The waste materials are then removed and stored in designated areas. This study aims to evaluate the mechani...The mining process involves drilling and excavation, resulting in the production of waste rock and tailings. The waste materials are then removed and stored in designated areas. This study aims to evaluate the mechanical strength and the environmental and economic impact of using Coltan Mining Waste (CMW) as a substitute for aggregates in concrete and mortar production. To achieve this, the CMW needs to be characterised. The Dreux Gorisse method was primarily used to produce concrete with a strength of 20 MPa at 28 days. The mortars, on the other hand, were formulated according to the NF P 18-452 standard. The environmental impact of using CMW as substitutes for natural aggregates in the production of concrete and mortar was analysed using SimaPro software. The results showed that mortars and concrete made with CMW have comparable compressive strengths to the reference mortar and concrete;reduce the negative impact on ecosystem quality, human health, resources, and climate change. It has also been shown that the substitution of aggregates by CMW reduces the cost of concrete and mortar as a function of the distance from the aggregate footprint.展开更多
The application of carbon nanomaterials, particularly graphene and carbon nanotubes, in cement-based composites is highly significant. These materials demonstrate the multifunctionality of carbon and offer extensive p...The application of carbon nanomaterials, particularly graphene and carbon nanotubes, in cement-based composites is highly significant. These materials demonstrate the multifunctionality of carbon and offer extensive possibilities for technological advancements. This research analyzes how the integration of graphene into cement-based composites enhances damping and mechanical properties, thereby contributing to the safety and durability of structures. Research on carbon nanomaterials is ongoing and is expected to continue driving innovation across various industrial sectors, promoting the sustainable development of building materials.展开更多
Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural str...Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural strength and compressive strength of cement mortar were studied by doping a certain amount of graphene oxide with cement mortar,and the strengthening mechanism of graphene oxide on cement mortar was obtained through microstructure detection.It is found that graphene oxide has a significant enhancement effect on the macroscopic mechanical properties of cement mortar,and graphene oxide provides nano-nucleation sites and growth templates for cement mortar,accelerates the hydration process,reduces the voids between hydration products,greatly increases the compactness,and improves the macroscopic properties of cement-based materials.展开更多
Wasting has been observed as a common feature of the human immunodeficiency virus (HIV) disease since the first reports and its presence increases the risk of death. There is no consensus on how to manage wasting asso...Wasting has been observed as a common feature of the human immunodeficiency virus (HIV) disease since the first reports and its presence increases the risk of death. There is no consensus on how to manage wasting associated with HIV. The goal of this study was to assess the effectiveness of a locally made Chickpea Sesame Based RUTF (CS-RUTF) in treating wasting associated with HIV in developing countries. Chronically sick adults from Mangochi Health District (Malawi) with wasting and confirmed or presumptive clinical diagnosis of HIV were recruited for the study. Subjects received a daily ration of 500 grams of CS-RUTF for 3 to 5 months. Nutrition status changes and mortality were used to assess the effectiveness of the intervention. There were 3 patterns of anthropometric responses continuous weight gain (WG), static weight (SW) and continuation weight loss (WL). The distribution of the 3 patterns is 53.9% (82/154) for the WG pattern, 9.1% (14/154) for the SW pattern and 37.0% (57/154) for the WL pattern. For the WG pattern, the overall median weight gain was 4.6 (2.4 to 7.1) kg. It was 5.7 (3.5 to 7.8) kg for those who completed 3 months of sup-plementation. MUAC and BMI changes followed similar pattern than weight change. Not being on HAART, acute diarrhoea during follow up, episode of reduced appetite during follow up, missing at least one visit were identified as risk factors for intervention failure. Overall, 38.5% (72/187) of study participants died during the intervention. In conclusion, despite that the study confirms the limited impact of food based interventions on mortality among wasted HIV positive individuals, it also suggests that supplementation with CS-RUTF may be an effective intervention for reversing wasting associated with HIV if combined with HAART and specific treatment of severe opportunistic infection causing diarrhoea and reducing appetite.展开更多
The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal con...The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.展开更多
This study deals with the analysis of the detrimental effects of a“sulfate attack”on cement mortar for different dry-wet cycles.The mass loss,tensile strength,and gas permeability coefficient were determined and ana...This study deals with the analysis of the detrimental effects of a“sulfate attack”on cement mortar for different dry-wet cycles.The mass loss,tensile strength,and gas permeability coefficient were determined and analyzed under different exposure conditions.At the same time,nitrogen adsorption(NAD),scanning electron microscopy(SEM),and X-ray diffraction(XRD)techniques were used to analyze the corresponding variations in the microstructure and the corrosion products.The results show that certain properties of the cement mortar evolve differently according to the durations of the dry-wet cycles and that some damage is caused to the mortars in aqueous solution.The pores fill with corrosion products,increasing the mortar specimen mass and tensile strength while reducing the permeability coefficient and pore size distribution.As corrosion proceeds,the crystallization pressure of the corrosion products increases,resulting in a 16%reduction in tensile strength from the initial value and a 2.6-factor increase in the permeability coefficient,indicating sensitivity to sulfate attack damage.Furthermore,the main corrosion products generated in the experiment are gypsum and ettringite.Application of osmotic pressure and extension of the immersion time can accelerate the erosion process.展开更多
We completed the uniaxial tensile test of mortar in the range of strain rate from 10^(-6)to 10^(-4)s^(-1)in the section containing softening,and carried out acoustic emission monitoring(AE)simultaneously.A series of A...We completed the uniaxial tensile test of mortar in the range of strain rate from 10^(-6)to 10^(-4)s^(-1)in the section containing softening,and carried out acoustic emission monitoring(AE)simultaneously.A series of AE parameters and spectrum analysis methods were used to identify the damage evolution process and cracking mechanism of mortar at different strain rates.The results show that,with the increase of strain rate,the peak stress and tensile elastic modulus of mortar increase obviously,and the stress level corresponding to the starting point of AE activity increases significantly as well,which indicates that the mechanical properties and AE characteristics of mortar have obvious strain rate effect.With the increase of strain rate,the cumulative AE hit decreases gradually,while the average AE hit rate increases significantly,indicating that the increase of strain rate reduces the damage degree of internal microstructure of the specimen,but the crack propagation speed increases.In the pre-peak stress stage,the average of AE ringing count and signal energy decreases with the increase of strain rate,while the average of duration increases;in the post-peak stress stage(f_(t)-30%f_(t)),the average of the three AE parameters all increase with the increase of strain rate,indicating that the strain rate effect on the damage process of mortar is different before and after peak stress,and the damage mechanism represented by different parameters is also different.In the whole process of uniaxial tensile of mortar,with the increase of strain rate,the scatter distribution of AE frequency-amplitude becomes more discrete,and the b-value shows a decreasing trend.In addition,the average level of AE peak frequency decreases with the increase of strain rate,while that of ca8 band wavelet energy spectrum coefficient increases.It is indicated that the increase of strain rate enables the crack propagation state of mortar specimen to become unstable,and the width of macrocrack increases but the proportion decreases.展开更多
This paper describes a study on the corrosion behavior of steel reinforcement in CAC mortars via electrochemical methods including corrosion potential,electrochemical impedance,and linear polarization evaluation.Resul...This paper describes a study on the corrosion behavior of steel reinforcement in CAC mortars via electrochemical methods including corrosion potential,electrochemical impedance,and linear polarization evaluation.Results indicate that there is a non-linear relationship between the corrosion degree of steel reinforcement in CAC mortar and the concentration of NaCl solution.The electrochemical parameters of specimens immersed in 3%NaCl solution suddenly drop at 40 days,earlier than 60 days of the reference.And the charge transfer resistivity of the specimen has decreased by 11 orders of magnitude at 40 days,showing an evident corrosion on steel reinforcement.However,it is interesting to notice that the corrosion is delayed by high external chloride concentration.The specimens immersed in 9%and 15%NaCl solutions remain in a relatively stable state within 120 days with slight pitting.The great corrosion protection of CAC concrete to embedded steel bars enables its wide application in marine.展开更多
Two different freeze-thaw cycles(FTC)are considered in this study to assess the related impact on gas permeability and micro-pore structure of a mortar.These are the water-freezing/water-thawing(WF-WT)and the air-free...Two different freeze-thaw cycles(FTC)are considered in this study to assess the related impact on gas permeability and micro-pore structure of a mortar.These are the water-freezing/water-thawing(WF-WT)and the air-freezing/air-thawing(AF-AT)cycles.The problem is addressed experimentally through an advanced nuclear magnetic resonance(NMR)technique able to provide meaningful information on the relationships among gas permeability,pore structure,mechanical properties,and the number of cycles.It is shown that the mortar gas permeability increases with the number of FTCs,the increase factor being 20 and 12.83 after 40 cycles for the WF-WT and AF-AT,respectively.The results also confirm that gas permeability hysteresis phenomena occur during the confining pressure loading and unloading process.展开更多
文摘Introduction: 68Ga-PSMA-11 is considered the gold standard in detection of micro and oligometastases in advanced prostate cancer, being used for therapeutic planning, as well as, potentially, for evaluating response to treatment. The development of ready-to-use lyophilized kit of PSMA-11 adds quality and safety to the routine use of this radiopharmaceutical and represents a pharmacotechnical challenge as it must preserve the integrity and specificity of the ligand. Methods: PSMA-11 kit formulation was proposed, considering radiolabeling parameters and the preservation of the peptide during the lyophilization process, using mannitol as an excipient. Critical temperature characterization studies were carried out using DSC equipment and the freeze-drying process was developed. The direct radiolabeling conditions were evaluated and standardized using 68Ge/68Ga generator eluate from two different manufacturers (ITG and Eckert & Ziegler). The radiochemical purity was evaluated by TLC and HPLC. Biological evaluation was carried out with lyophilized PSMA-11 to demonstrate the integrity of the peptide and preservation of biological activity after the lyophilization process. Results: Based on critical temperature characterization studies, the freeze-drying cycle was designed to reach a freezing temperature of around −40˚C and primary drying at 2˚C. Using 20 mg of mannitol, an intact and elegant lyophilized cake was obtained. PSMA-11 lyophilized kit was directly labeled with 68Ga eluate from 68Ge/68Ga GMP generators (ITG and Eckert & Ziegler) resulting in % RP > 95% at pH 4.0 to 4.5. The results obtained from in vitro and in vivo biological competition studies confirmed the preservation of PSMA-11 affinity for the receptor after lyophilization. Conclusion: A lyophilized formulation (Kit) of PSMA-11 was successfully obtained, which preserved the integrity and biological activity of the peptide and guaranteed radiolabeling efficiency.
基金Funded by the National Natural Science Foundation of China (Nos. 52278269, 52278268, 52178264, 52108238)Tianjin Outstanding Young Scholars Science Fund Project (No. 22JCJQJC00020)State Key Laboratory of Green Building Materials Open Foundation (No. 2021GBM08)。
文摘To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.
基金the National Natural Science Foundation of China(52172017 and 51902095).
文摘Cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties.This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement mortar.The results show that K-SAP significantly affects the cement mortar’s rheological behavior,with distinct phases of water absorption and release,leading to changes in workability over time.Furthermore,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics.Notably,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage behavior.Moreover,K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP.
基金Funded by the the Shaanxi Provincial Natural Science Basic Research Plan(No.2021JQ-471)the Natural Science Project of Shaanxi Provincial Department of Education(No.21JK0802)。
文摘To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing conditions.An SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer mortar.Meanwhile,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage coefficient.The experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and time.Finally,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.
基金Funded by the National Key Research and Development Program of China(No.2023YFB260012602)the Shandong Provincial Natural Science Foundation(No.ZR2023ME208)。
文摘To investigate the freeze-thaw(F-T)damages and failure characteristics of rock mass with arc-shaped joints in cold regions,three types of cement mortar specimens with different central angles and prefabricated arc-shaped flaws are subjected to uniaxial compressive tests under different F-T cycles.Experimental observations show that the uniaxial compressive strength of specimens are significantly influenced by F-T cycles and their failure modes are mainly affected by the central angleαof the prefabricated flaws.Unlike the specimens with a central angle of 60°,the specimens with a central angle of 120°and 180°have greater curvature of flaws,so tensile cracks occur in the arc-top area of their prefabricated flaws.According to experimental images observed by environmental scanning electron microscope(ESEM),as the number of F-T cycles increases,the deterioration effect of the specimen becomes more obvious,which is specifically reflected in the increase of the mass loss,peak stress loss,and damage variables as a power function,and the peak strain decreases as a quadratic polynomial.According to numerical results using two-dimensional particle flow code(PFC2D),it is found that F-T cycles cause more damage to the specimen in the early stages than in the later ones.The area of the concentrated compressive stress zone in the middle is decreased due to the increased number of F-T cycles,while the area of the surrounding tensile-shear stress zone is increased.The models appear different failure modes due to the release of concentrated stress in different tensile-shear zones.
基金This work is supported by the Zhuhai Science and Technology Project(ZH22036203200015PWC)the Open Foundation of State Key Laboratory of Subtropical Building Science(2022ZB20).
文摘In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.
基金“Key Science and Technology Project of Guangxi Department of Communications-Technology Development and Application of Cement Red Clay Stabilized Sea Sand Semi-Rigid Subgrade”(Grant:Gui Jiaotong 2020-No.150)“Key Science and Technology Project of Guangxi Department of Transportation-Key Technologies and Application Demonstrations for the Multi-Solid Waste Co-Processing of Bayer Red Mud in Large-Scale Road Construction”(Grant:Gui Jiaotong 2021-No.148).
文摘Red mud(RM)is a low-activity industrial solid waste,and its utilization as a resource is currently a hot topic.In this study,the micro characteristics of red mud at different calcination temperatures were analyzed using X-ray diffraction and scanning electron microscopy.The performance of calcined red mud was determined through mortar strength tests.Results indicate that high-temperature calcination can change the mineral composition and microstructure of red mud,and increase the surface roughness and specific surface area.At the optimal temperature of 700°C,the addition of calcined red mud still leads to a decrease in mortar strength,but its activity index and flexural coefficient increase by 16.2%and 11.9%with respect to uncalcined red mud,reaching values of 0.826 and 0.974,respectively.Compared with the control group,the synergistic activation of calcined red mud with slag can increase the compressive and flexural strength of the mortar by 12.9%and 1.5%,reaching 8.7 and 62.4 MPa,respectively.Correspondingly,the activity index and flexural coefficient of the calcined RM and GGBS(Ground Granulated Blast furnace Slag)mixtures also increase to 1.015 and 1.130,respectively.
基金Funded by the National Natural Science Foundation of China(No.52008046)Young Elite Scientists Sponsorship Program from JSAST(No.TJ-2023-024)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_2848)。
文摘This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.
基金This article was funded by the National Natural Science Foundation of China(No.51408610).
文摘Purpose–During the construction process of the China Railway Track System(CRTS)I type filling layer,the nonwoven fabric bags have been used as grouting templates for cement asphalt(CA)emulsified mortar.The porous structure of nonwoven fabrics endowed the templates with breathability and water permeability.The standard requires that the volume expansion rate of CA mortar must be controlled within 1%–3%,which can generate expansion pressure to ensure that the cavities under track slabs are filled fully.However,the expansion pressure caused some of the water to seep out from the periphery of the filling bag,and it would affect the actual mix proportion of CA mortar.The differences in physical and mechanical properties between the CA mortar under track slabs and the CA mortar formed in the laboratory were studied in this paper.The relevant results could provide important methods for the research of filling layer materials for CRTS I type and other types of ballastless tracks in China.Design/methodology/approach–During the inspection of filling layer,the samples of CA mortar from different working conditions and raw materials were taken by uncovering the track slabs and drilling cores.The physical and mechanical properties of CA mortar under the filling layer of the slab were systematically analyzed by testing the electrical flux,compressive strength and density of mortar in different parts of the filling layer.Findings–In this paper,the electric flux,the physical properties and mechanical properties of different parts of CA mortar under the track slab were investigated.The results showed that the density,electric flux and compressive strength of CA mortar were affected by the composition of raw materials for dry powders and different parts of the filling layer.In addition,the electrical flux of CA mortar gradually decreased within 90 days’age.The electrical flux of samples with the thickness of 54 mm was lower than 500 C.Therefore,the impermeability and durability of CA mortar could be improved by increasing the thickness of filling layer.Besides,the results showed that the compressive strength of CA mortar increased,while the density and electric flux decreased gradually,with the prolongation of hardening time.Originality/value–During 90 days’age,the electrical flux of the CA mortar gradually decreased with the increase of specimen thickness and the electrical flux of the specimens with the thickness of 54 mm was lower than 500 C.The impermeability and durability of the CA mortar could be improved by increasing the thickness of filling layer.The proposed method can provide reference for the further development and improvement of CRTS I and CRTS II type ballastless track in China.
基金the National Natural Science Foundation of China(No.51709097).
文摘This study focuses on the effect of ultrafine waste glass powder on cement strength,gas permeability and pore structure.Varying contents were considered,with particle sizes ranging from 2 to 20μm.Moreover,alkali activation was considered to ameliorate the reactivity and cementitious properties,which were assessed by using scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),and specific surface area pore size distribution analysis.According to the results,without the addition of alkali activators,the performance of glass powder mortar decreases as the amount of glass powder increases,affecting various aspects such as strength and resistance to gas permeability.Only 5%glass powder mortar demonstrated a compressive strength at 60 days higher than that of the control group.However,adding alkali activator(CaO)during hydration ameliorated the hydration environment,increased the alkalinity of the composite system,activated the reactivity of glass powder,and enhanced the interaction of glass powder and pozzolanic reaction.In general,compared to ordinary cement mortar,alkali-activated glass powder mortar produces more hydration products,showcases elevated density,and exhibits improved gas resistance.Furthermore,alkali-activated glass powder mortar demonstrates an improvement in performance across various aspects as the content increases.At a substitution rate of 15%,the glass powder mortar reaches its optimal levels of strength and resistance to gas permeability,with a compressive strength increase ranging from 28.4%to 34%,and a gas permeation rate reduction between 51.8%and 66.7%.
文摘The mining process involves drilling and excavation, resulting in the production of waste rock and tailings. The waste materials are then removed and stored in designated areas. This study aims to evaluate the mechanical strength and the environmental and economic impact of using Coltan Mining Waste (CMW) as a substitute for aggregates in concrete and mortar production. To achieve this, the CMW needs to be characterised. The Dreux Gorisse method was primarily used to produce concrete with a strength of 20 MPa at 28 days. The mortars, on the other hand, were formulated according to the NF P 18-452 standard. The environmental impact of using CMW as substitutes for natural aggregates in the production of concrete and mortar was analysed using SimaPro software. The results showed that mortars and concrete made with CMW have comparable compressive strengths to the reference mortar and concrete;reduce the negative impact on ecosystem quality, human health, resources, and climate change. It has also been shown that the substitution of aggregates by CMW reduces the cost of concrete and mortar as a function of the distance from the aggregate footprint.
文摘The application of carbon nanomaterials, particularly graphene and carbon nanotubes, in cement-based composites is highly significant. These materials demonstrate the multifunctionality of carbon and offer extensive possibilities for technological advancements. This research analyzes how the integration of graphene into cement-based composites enhances damping and mechanical properties, thereby contributing to the safety and durability of structures. Research on carbon nanomaterials is ongoing and is expected to continue driving innovation across various industrial sectors, promoting the sustainable development of building materials.
基金This work were supported by Natural Science Foundation of Zhejiang Province(LQ23E080003)a Doctoral program of Zhejiang University of science and technology(F701104L08)The Special Fund Project of Zhejiang University of Science and Technology's Basic Scientific Research Business Expenses in 2023(2023QN016).
文摘Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural strength and compressive strength of cement mortar were studied by doping a certain amount of graphene oxide with cement mortar,and the strengthening mechanism of graphene oxide on cement mortar was obtained through microstructure detection.It is found that graphene oxide has a significant enhancement effect on the macroscopic mechanical properties of cement mortar,and graphene oxide provides nano-nucleation sites and growth templates for cement mortar,accelerates the hydration process,reduces the voids between hydration products,greatly increases the compactness,and improves the macroscopic properties of cement-based materials.
文摘Wasting has been observed as a common feature of the human immunodeficiency virus (HIV) disease since the first reports and its presence increases the risk of death. There is no consensus on how to manage wasting associated with HIV. The goal of this study was to assess the effectiveness of a locally made Chickpea Sesame Based RUTF (CS-RUTF) in treating wasting associated with HIV in developing countries. Chronically sick adults from Mangochi Health District (Malawi) with wasting and confirmed or presumptive clinical diagnosis of HIV were recruited for the study. Subjects received a daily ration of 500 grams of CS-RUTF for 3 to 5 months. Nutrition status changes and mortality were used to assess the effectiveness of the intervention. There were 3 patterns of anthropometric responses continuous weight gain (WG), static weight (SW) and continuation weight loss (WL). The distribution of the 3 patterns is 53.9% (82/154) for the WG pattern, 9.1% (14/154) for the SW pattern and 37.0% (57/154) for the WL pattern. For the WG pattern, the overall median weight gain was 4.6 (2.4 to 7.1) kg. It was 5.7 (3.5 to 7.8) kg for those who completed 3 months of sup-plementation. MUAC and BMI changes followed similar pattern than weight change. Not being on HAART, acute diarrhoea during follow up, episode of reduced appetite during follow up, missing at least one visit were identified as risk factors for intervention failure. Overall, 38.5% (72/187) of study participants died during the intervention. In conclusion, despite that the study confirms the limited impact of food based interventions on mortality among wasted HIV positive individuals, it also suggests that supplementation with CS-RUTF may be an effective intervention for reversing wasting associated with HIV if combined with HAART and specific treatment of severe opportunistic infection causing diarrhoea and reducing appetite.
文摘The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.
基金This work is supported by the National Natural Science Foundation of China(No.51709097).
文摘This study deals with the analysis of the detrimental effects of a“sulfate attack”on cement mortar for different dry-wet cycles.The mass loss,tensile strength,and gas permeability coefficient were determined and analyzed under different exposure conditions.At the same time,nitrogen adsorption(NAD),scanning electron microscopy(SEM),and X-ray diffraction(XRD)techniques were used to analyze the corresponding variations in the microstructure and the corrosion products.The results show that certain properties of the cement mortar evolve differently according to the durations of the dry-wet cycles and that some damage is caused to the mortars in aqueous solution.The pores fill with corrosion products,increasing the mortar specimen mass and tensile strength while reducing the permeability coefficient and pore size distribution.As corrosion proceeds,the crystallization pressure of the corrosion products increases,resulting in a 16%reduction in tensile strength from the initial value and a 2.6-factor increase in the permeability coefficient,indicating sensitivity to sulfate attack damage.Furthermore,the main corrosion products generated in the experiment are gypsum and ettringite.Application of osmotic pressure and extension of the immersion time can accelerate the erosion process.
基金Funded by the National Natural Science Foundation of China(No.51878245)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_0622)。
文摘We completed the uniaxial tensile test of mortar in the range of strain rate from 10^(-6)to 10^(-4)s^(-1)in the section containing softening,and carried out acoustic emission monitoring(AE)simultaneously.A series of AE parameters and spectrum analysis methods were used to identify the damage evolution process and cracking mechanism of mortar at different strain rates.The results show that,with the increase of strain rate,the peak stress and tensile elastic modulus of mortar increase obviously,and the stress level corresponding to the starting point of AE activity increases significantly as well,which indicates that the mechanical properties and AE characteristics of mortar have obvious strain rate effect.With the increase of strain rate,the cumulative AE hit decreases gradually,while the average AE hit rate increases significantly,indicating that the increase of strain rate reduces the damage degree of internal microstructure of the specimen,but the crack propagation speed increases.In the pre-peak stress stage,the average of AE ringing count and signal energy decreases with the increase of strain rate,while the average of duration increases;in the post-peak stress stage(f_(t)-30%f_(t)),the average of the three AE parameters all increase with the increase of strain rate,indicating that the strain rate effect on the damage process of mortar is different before and after peak stress,and the damage mechanism represented by different parameters is also different.In the whole process of uniaxial tensile of mortar,with the increase of strain rate,the scatter distribution of AE frequency-amplitude becomes more discrete,and the b-value shows a decreasing trend.In addition,the average level of AE peak frequency decreases with the increase of strain rate,while that of ca8 band wavelet energy spectrum coefficient increases.It is indicated that the increase of strain rate enables the crack propagation state of mortar specimen to become unstable,and the width of macrocrack increases but the proportion decreases.
基金Funded by National Natural Science Foundation of China(Nos.51772212,51402216,51978505)。
文摘This paper describes a study on the corrosion behavior of steel reinforcement in CAC mortars via electrochemical methods including corrosion potential,electrochemical impedance,and linear polarization evaluation.Results indicate that there is a non-linear relationship between the corrosion degree of steel reinforcement in CAC mortar and the concentration of NaCl solution.The electrochemical parameters of specimens immersed in 3%NaCl solution suddenly drop at 40 days,earlier than 60 days of the reference.And the charge transfer resistivity of the specimen has decreased by 11 orders of magnitude at 40 days,showing an evident corrosion on steel reinforcement.However,it is interesting to notice that the corrosion is delayed by high external chloride concentration.The specimens immersed in 9%and 15%NaCl solutions remain in a relatively stable state within 120 days with slight pitting.The great corrosion protection of CAC concrete to embedded steel bars enables its wide application in marine.
基金supported by the National Natural Science Foundation of China(Grant No.51709097).
文摘Two different freeze-thaw cycles(FTC)are considered in this study to assess the related impact on gas permeability and micro-pore structure of a mortar.These are the water-freezing/water-thawing(WF-WT)and the air-freezing/air-thawing(AF-AT)cycles.The problem is addressed experimentally through an advanced nuclear magnetic resonance(NMR)technique able to provide meaningful information on the relationships among gas permeability,pore structure,mechanical properties,and the number of cycles.It is shown that the mortar gas permeability increases with the number of FTCs,the increase factor being 20 and 12.83 after 40 cycles for the WF-WT and AF-AT,respectively.The results also confirm that gas permeability hysteresis phenomena occur during the confining pressure loading and unloading process.
