BACKGROUND Psychological intervention nursing(PIN)has been considered to have a curative effect on cesarean section(CS)post-operative recovery.However,the therapeutic mechanisms remain obscure.AIM To explore the effec...BACKGROUND Psychological intervention nursing(PIN)has been considered to have a curative effect on cesarean section(CS)post-operative recovery.However,the therapeutic mechanisms remain obscure.AIM To explore the effects of PIN combined with acupressure massage on CS postoperative recovery.METHODS A retrospective study was conducted on 150 pregnant women admitted to an obstetrics department between January 2020 and January 2023.The control group(CG)received acupressure therapy(n=73),and the intervention group(IG)received acupressure therapy and PIN therapy(n=77).Postoperative recovery time was assessed by anal-exhausting,defecation,bed activity,breastfeeding,and hospital stay times.Adverse effects,including infection,bleeding,limb numbness,intrauterine hematoma,urinary retention,and venous thromboembolism,were recorded.the pain visual analogue scale(VAS)was used to evaluate the degree of pain.Anxiety and depression status were qualitatively assessed using the selfrating anxiety scale(SAS),self-rating depression scale(SDS),and Edinburgh postpartum depression scale(EPDS).The Pittsburgh sleep quality index(PSQI)was used to compare sleep quality between the groups.RESULTS The baseline data and SAS,SDS,EPDS,and PSQI scores did not significantly differ before CS(P>0.05)and neither did complication rates between the two groups after CS(P>0.05).However,anal-exhausting,defecation,waking up,breastfeeding,and hospitalization times were significantly shorter for participants in the IG than those for participants in the CG(P<0.05).The VAS,SAS,SDS,EPDS,and PSQI scores of the IG were significantly lower than those of the CG(P<0.05).CONCLUSION PIN,combined with acupressure massage,effectively promotes maternal recovery,reduces post-CS pain,and improves post-operative negative emotions and sleeping quality.展开更多
The clinic applications of bioabsorbable magnesium(Mg)and its alloys have been significantly restricted owing to their poor corrosion resistance.Besides elemental alloying,surface modification and functionality is a m...The clinic applications of bioabsorbable magnesium(Mg)and its alloys have been significantly restricted owing to their poor corrosion resistance.Besides elemental alloying,surface modification and functionality is a major approach to increasing corrosion resistance for magnesium alloys.This article reviews the cutting-edge advances and progress of biodegradable surface coatings upon Mg alloys over the last decades,aims to build up a knowledge framework of surface modification on biodegradable Mg alloys.A considerable number of conversion,deposition,mechanical and functional coatings and their preparation methods are discussed.The emphasis has been placed on the composition of chemical conversion and deposited coatings to overcome the disadvantages of adhesion,corrosion resistance and biocompatibility of a single coating for biomedical materials.The issues have been addressed on the integration of the structural and functional factors of the composite coatings.展开更多
BACKGROUND: Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay a...BACKGROUND: Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay and have higher mortality and graft loss rates compared with those without graft dysfunction. However, because of the lack of universally accepted definition, early diagnosis of graft dysfunction is difficult. Additionally, numerous factors affect the allograft function after transplantation, making the prediction of PGD more difficult. The present review was to analyze the literature available on PGD and to propose a definition.DATA SOURCE: A search of PubMed (up to the end of 2012) for English-language articles relevant to PGD was performed to clarify the characteristics, risk factors, and possible treatments or interventions for PGD.RESULTS: There is no pathological diagnostic standard; many documented definitions of PGD are different. Many factors such as donor status, procurement and transplant process and recipient illness may affect the function of graft, and ischemia reperfusion injury is considered the direct cause. Potentia managements which are helpful to improve graft function were investigated. Some of them are promising.CONCLUSIONS: Our analyses suggested that the definition of PGD should include one or more of the following variables: (1)bilirubin ≥10 mg/dL on postoperative day 7; (2) internationa normalized ratio ≥1.6 on postoperative day 7; and (3) alanine aminotransferase or aspartate aminotransferase 】2000 IU/L within 7 postoperative days. Reducing risk factors may decrease the incidence of PGD. A majority of the recipients could recover from PGD; however, when the graft progresses intoprimary non-function, the patients need to be treated with retransplantation.展开更多
AIM. To investigate the influence of heme oxygenase-1 （HO-1） gene transfer on the viability and function of cultured rat islets in vitro. METHODS： Islets were isolated from the pancreata of Sprague-Dawley rats by i...AIM. To investigate the influence of heme oxygenase-1 （HO-1） gene transfer on the viability and function of cultured rat islets in vitro. METHODS： Islets were isolated from the pancreata of Sprague-Dawley rats by intraductal collagenase digestion, and purified by discontinuous Ficoll density gradient centrifugation. Purified rat islets were transfected with adenoviral vectors containing human HO-1 gene （Ad- HO-1） or enhanced green fluorescent protein gene （Ad- EGFP）, and then cultured for seven days. Transfection was confirmed by fluorescence microscopy and Western blot. Islet viability was evaluated by acridine orange/ propidium iodide fluorescent staining. Glucose-stimulated insulin release was detected using insulin radioimmunoassay kits and was used to assess the function of islets. Stimulation index （SI） was calculated by dividing the insulin release upon high glucose stimulation by the insulin release upon low glucose stimulation. RESULTS： After seven days culture, the viability of cultured rat islets decreased significantly （92% ± 6% vs 52% ± 13%, P 〈 0.05）, and glucose-stimulated insulin release also decreased significantly （6.47 ± 0.55 mIU/ L/30IEO vs 4.57 ± 0.40 mIU/L/3OIEO., 14.93 ± 1.17 mIU/L/30IEQ vs 9.63 ± 0.71 mIU/L/30IEQ, P 〈 0.05）. Transfection of rat islets with adenoviral vectors at an 1±10 of 20 was efficient, and did not impair islet function. At 7 d post-transfection, the viability of Ad-HO-1 transfected islets was higher than that of control islets（71% ± 15% vs 52% ± 13%, P 〈 0.05）. There was no significant difference in insulin release upon low glucose stimulation （2.8 mmol/L） among Ad-HO-1 transfected group, Ad-EGFP transfected group, and control group （P 〉 0.05）, while when stimulated by high glucose （16.7 mmol/L） solution, insulin release in Ad-HO-1 transfected group was significantly higher than that in Ad-EGFP transfected group and control group, respectively （12.50 ±2.17 mIU/L/30IEQ vs 8.87 ± 0.65 mIU/L/30IEQ, 12.50 ± 2.17 mIU/L/30IEQ vs 9.63 ± 0.71 mIU/L/30IEQ, P 〈 0.05）. The SI of Ad-HO-1 transfected group was also significantly higher than that of Ad-EGFP transfected group and control group, respectively （2.21 ± 0.02 vs 2.08 ± 0.05; 2.21 ± 0.02 vs 2.11 ± 0.03, P 〈 0.05）. CONCLUSION： The viability and function of rat islets decrease over time in in vitro culture, and heine oxygenase-1 gene transfer could improve the viability and function of cultured rat islets.展开更多
Protein adsorption preferentially occurs and significantly affects the physicochemical reactions once the biodegradable magnesium alloys as bone replacements have been implanted. To date, interactions mechanisms betwe...Protein adsorption preferentially occurs and significantly affects the physicochemical reactions once the biodegradable magnesium alloys as bone replacements have been implanted. To date, interactions mechanisms between Mg implants and proteins remain unclear at a molecular level. Thereby, a combination of molecular dynamic(MD) simulations and experimental exploration is used to investigate the adsorption behavior and conformational change of bovine serum albumin(BSA), a representative protein of blood plasma, upon the surface of microarc oxidation(MAO) coated Mg alloy AZ31. The influences of absorbed proteins on the cytocompatibility of MAO coating are evaluated by virtue of cytotoxicity assay. Results indicate that the negatively charged O atoms(BSA) exhibit strong interaction with Mg^(2+) ions of Mg(OH)_(2), revealing that BSA molecules are ionically adsorbed on the AZ31 surface. Interestingly, MD simulation reveals that MAO coating demonstrates superior ability to capture BSA molecules during the process of adsorption owing to strong electric attraction between the negatively charged O atoms in BSA molecules with Mg atoms of MgO in MAO coating. Moreover, the α-helix part of absorbed BSA molecules on AZ31 substrate and MAO coating markedly decreases with an increase in β-sheet, β-turn and unordered contents, which is attributed to the reduction in the number of hydrogen bonds in BSA molecules. Furthermore, the adsorbed BSA molecules improve the cytocompatibility of MAO coating since the positively charged-NH_(3)^(+) group and β-sheet content of absorbed BSA molecules mediate the cell adhesion by interacting with the negatively charged cell membrane.展开更多
The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds ...The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil,and their catalytic cracking performance was investigated.There are nine classes of basic nitrogen compounds(BNCs)and eleven classes of non-basic heteroatomic compounds(NBHCs)in the different distillates.The dominant BNCs are mainly basic N1 class species.The dominant NBHCs are mainly acidic O2 and O1 class species in the300-350℃,350-400℃,and 400-450℃distillates,while the neutral N1,N1 O1 and N2 compounds become relatively abundant in the>450℃fraction.The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation(different carbon number)but not by aromaticity(different double-bond equivalent values).The basic N1 O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity.After the catalytic cracking of Fushun shale oil,the classes of BNCs in the liquid products remain unchanged,while the classes and relative abundances of NBHCs vary significantly.展开更多
A Schiff base(a compound containing a C=N bond)induced anodic Ca−P coating was prepared on AZ31 Mg alloy in a mixed solution of CaCl_(2) and KH_(2)PO_(4) at 60℃ in the presence of glucose and L-cysteine.The microstru...A Schiff base(a compound containing a C=N bond)induced anodic Ca−P coating was prepared on AZ31 Mg alloy in a mixed solution of CaCl_(2) and KH_(2)PO_(4) at 60℃ in the presence of glucose and L-cysteine.The microstructure and chemical composition of the coatings were characterized using FE-SEM,FT-IR,XRD,and XPS.The in vitro degradation resistance of the coated samples was evaluated via potentiodynamic polarization(PDP),electrochemical impedance spectroscopy(EIS),and hydrogen evolution test.The experimental results show that the Ca−PSchiff base coating is composed of CaHPO_(4)(DCPA)and hydroxyapatite(HA),whereas HA is not present in the Ca−P coating.The Ca−P_(Schiff base) coating thickness is about 2 times that of Ca−P coating(Ca−P coating:(9.13±4.20)μm and Ca−P_(Schiff base):(18.13±5.78)μm).The corrosion current density of the Ca−P_(Schiff base) coating is two orders of magnitude lower than that of the Ca−P coating.The formation mechanism of the Ca−P_(Schiff base) is proposed.展开更多
BACKGROUND Anastomosis of the testicular vein with the superior mesenteric vein rarely causes severe gastrointestinal bleeding.To date,there have been few studies describing its appearance on medical imaging.Here,we p...BACKGROUND Anastomosis of the testicular vein with the superior mesenteric vein rarely causes severe gastrointestinal bleeding.To date,there have been few studies describing its appearance on medical imaging.Here,we present multidetector computed tomography three-dimensional and multiplanar reconstruction(MPR)images of a typical digital subtraction angiography showing proven ectopic bleeding and provide the first review of the image performance.CASE SUMMARY A 68-year-old man who had been rushed to the hospital with a four-day history of melena and fainting underwent multiple esophagogastroduodenoscopy procedures that failed to identify the source of bleeding.We used MPR combined with three-dimensional reconstruction images,and found that the testicular vein had anastomosed with the superior mesenteric vein,and they clustered together in the jejunal vessel wall,which caused severe gastrointestinal bleeding.Digital subtraction angiography confirmed the location of bleeding.After transfusion and embolization therapy,the patient’s condition improved.CONCLUSION Computed tomography-MPR combined with three-dimensional images offers significant value in the localization and qualitative assessment of rare gastrointestinal hemorrhage.The features of multiphase spiral scanning can improve the accuracy of the diagnosis.展开更多
Objective:To study the change of pituitary tumor transforming gene 1 (PTTG1) expression in prostate cancer and its correlation with proliferation and invasion genes.Methods: Patients with prostate cancer who underwent...Objective:To study the change of pituitary tumor transforming gene 1 (PTTG1) expression in prostate cancer and its correlation with proliferation and invasion genes.Methods: Patients with prostate cancer who underwent radical operation in our hospital between March 2015 and January 2018 were selected as the malignant group of the research, and the prostate cancer lesions were collected;patients who underwent transurethral resection of the prostate due to benign prostatic hyperplasia in our hospital during the same period were selected as the benign group of the research, and the benign prostate lesions were collected. The mRNA expression levels of PTTG1, proliferation genes and invasion genes in the lesions were determined. Results:PTTG1, Survivin, Bcl-2, CyclinD1, GPRC6A, ZEB1, CatB, CatD and PAR-1 mRNA expression in prostate cancer lesions of malignant group were significantly higher than those of benign group whereas CDKN2, p21 and TFPI2 mRNA expression were significantly lower than those of benign group;Survivin, Bcl-2, CyclinD1, GPRC6A, ZEB1, CatB, CatD and PAR-1 mRNA expression in prostate cancer lesions with high PTTG1 were significantly higher than those in prostate cancer lesions with low PTTG1 whereas CDKN2, p21 and TFPI2 mRNA expression were significantly lower than those in prostate cancer lesions with low PTTG1.Conclusion:The PTTG1 gene is highly expressed in prostate cancer lesions and it is closely related to the changes of proliferation and invasion gene expression.展开更多
Ingenious establishment of transition metal-nitrogen-carbon electrocatalysts with diverse catalytic active sites and hierarchically porous frameworks is highly significant to boost the oxygen reduction reaction(ORR)in...Ingenious establishment of transition metal-nitrogen-carbon electrocatalysts with diverse catalytic active sites and hierarchically porous frameworks is highly significant to boost the oxygen reduction reaction(ORR)in Zn-air batteries(ZABs).In this study,Fe/Co co-doped zeolitic imidazolium frameworks(ZIFs)and graphitic carbon nitride(g-C_(3)N_(4))were integrated and pyrolyzed to construct carbon-based electrocatalysts containing Fe,Co and N elements(labelled as Co-CoFe@NRPC),in which atomic-sc ale FeN_x and CoN_x,and nano scale metallic Co and CoFe alloy moieties were aligned with hierarchically porous N-doped carbon frameworks constructed by interconnected micropolyhedrons,nano tubes and nanosheets.The diverse active moieties guaranteed excellent intrinsic catalytic activity,while the hierarchically porous N-doped carbon frameworks ensured admirable accessibility of the catalytic active sites,excellent electrical conductivity,satisfactory mass transport and good durability.Expectedly,the optimized Co-CoFe@NRPC-90(with 90 mg g-C_(3)N_(4) added)electrocatalyst exhibited excellent ORR performance with a high half-wave potential of 885 mV(vs.reversible hydrogen electrode(RHE)),diffusion-limiting current density of 6.15 mA·cm^(-2),desirable durability and methanol tolerance.Simultaneously,the liquid ZAB established with Co-CoFe@NRPC-90 as an air-cathode electrocatalyst manifested an outstanding power density(281 mW·cm^(-2))and specific capacity(820.9 mAh·g_(Zn)^(-1)),transcending the liquid ZAB based on a commercial Pt/C electrocatalyst.展开更多
Magnesium(Mg) alloys possess comparable physical and mechanical properties to bone, making them an outstanding candidate of implant materials for bone fracture treatment. In addition to the excellent biocompatibility,...Magnesium(Mg) alloys possess comparable physical and mechanical properties to bone, making them an outstanding candidate of implant materials for bone fracture treatment. In addition to the excellent biocompatibility, and bioactivity, the engagement of Mg alloys is key for a number of biological functionalities in the human body. The unique biodegradation nature of Mg alloy implants implies that it may not require a secondary removal procedure when the expected supporting tasks accomplish, as they may simply and safely "disappear" over time. Nonetheless, the demonstrated drawback of potentially rapid degradation, is an issue that must be addressed appropriately for Mg implants and is consequently given unique attention in this review article. Herein, the critical criteria and the state-of-the-art strategies for controlling the degradation process of Mg alloys are reported. Furthermore, future developments of biodegradable Mg and its alloys systems with satisfactory specifications for clinical trials and deployment,are discussed. This review aims to provide information to materials scientists and clinical practitioners in the context of developing practical biodegradable Mg alloys.展开更多
Magnesium(Mg)and its alloys have been widely used in a variety of industrial fields,however,the high corrosion rate and surface contamination restrict their applications.In this study,a corrosion-resistant polymer coa...Magnesium(Mg)and its alloys have been widely used in a variety of industrial fields,however,the high corrosion rate and surface contamination restrict their applications.In this study,a corrosion-resistant polymer coating with self-cleaning properties on Mg alloy AZ31 was successfully fabricated via a pretreatment of amino-silane(poly(3-aminopropyl)trimethoxysilane,PAPTMS)and subsequently covered with a polypropylene(PP)film.Surface morphology and chemical compositions were examined using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),and Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS)as well.Contact angle was measured to determine hydrophobicity of the composite coatings.Water permeability of the coatings was evaluated through electrochemical impedance spectroscopy(EIS).Corrosion resistance of the coating was investigated using electrochemical and hydrogen evolution tests.Results indicated that PAPTMS/PP coatings possessed a micrometer-scaled porous spherical microstructure,and super-hydrophobicity with high water contact angle(162±3.4°)and low sliding angle(5±0.6°)due to the low surface energy(10.38 mJ/m2).Moreover,the coating exhibited a smaller water diffusion coefficient(8.12×10-10 cm2/s)and water uptake volume fraction(24.5%),demonstrating low water permeability and good physical barrier performance.As a result,the corrosion current density of PAPTMS/PP coating exhibited approximately three orders of magnitude lower than that of the AZ31 substrate,suggesting excellent corrosion resistance.Finally,corrosion-resistant mechanism of the hybrid coating was proposed.展开更多
A hexagonal nanosheet Mg(OH)2 coating was prepared through a one-step hydrothermal method using LiOH solution as mineralizer and then modified by ethylenediaminetetraacetic acid(EDTA) to minimize the rapid corrosion o...A hexagonal nanosheet Mg(OH)2 coating was prepared through a one-step hydrothermal method using LiOH solution as mineralizer and then modified by ethylenediaminetetraacetic acid(EDTA) to minimize the rapid corrosion of AZ31 Mg alloy.The performance of the coating was evaluated using electrochemical technique,hydrogen evolution measurements, nanoscratch test,Fourier-transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) patterns and field-emission scanning electron microscopy(FESEM).The results suggested that the corrosion rate of bare AZ31 Mg alloys was significantly reduced by one and two orders of magnitude through the protection from Mg(OH)2 coating and modification with EDTA(i.e., EDTA-Mg(OH)2 coating), respectively.FESEM micrographs indicated that the modification in EDTA elicits to the formation of an EDTA-Mg(OH)2 composite with a thickness as twice as that of as-prepared Mg(OH)2 coating.Nanoscratch tests revealed strong adhesion between the composite or Mg(OH)2 coating and the substrate.The study of formation and corrosion mechanisms of the coatings manifested that Mg(OH)2 was first formed near the intermetallic compound AlMn particles and gradually covered the entire surface, wherein the AlMn particles played an important role in the coating growth process.And it also proved that EDTA accelerated the formation of Mg(OH)2.展开更多
Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemica...Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemical compositions and surface morphologies of the coatings were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FESEM). Results indicated that the composite coatings consisted of polymethyltrimethoxysilane (PMTMS), LDH and Mg(OH)2. Electrochemical and hydrogen evolution measurements revealed that the composite coatings possessed good corrosion resistance, especially the ones prepared in a high hydrolysis degree of silane. The optimum corrosion resistance of the composite coati ng was LDH/PMTMS-3 coating, which had the lowest value of corrosion current density (5.537×10^-9 A·cm^-2) and a dense surface.Plausible mechanism for coating formation and corrosion process of MTMS-modified Mg(OH)2/Mg-Al-LDH coatings were discussed.展开更多
To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated accordi...To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.展开更多
Biodegradable Mg alloys have generated great interest for biomedical applications. Accurate predictions of in vivo degradation of Mg alloys through costeffective in vitro evaluations require the latter to be conducted...Biodegradable Mg alloys have generated great interest for biomedical applications. Accurate predictions of in vivo degradation of Mg alloys through costeffective in vitro evaluations require the latter to be conducted in an environment close to that of physiological scenarios. However, the roles of glucose and buffering agents in regulating the in vitro degradation performance of Mg alloys has not been elucidated. Herein, degradation behavior of AZ31 alloy is investigated by hydrogen evolution measurements, pH monitoring and electrochemical tests. Results indicate that glucose plays a content-dependent role in degradation of AZ31 alloy in buffer-free saline solution. The presence of a low concentration of glucose, i.e. 1.0 g/L, decreases the corrosion rate of Mg alloy AZ31, whereas the presence of 2.0 and 3.0 glL glucose accelerates the corrosion rate during long term immersion in saline solution. In terms of Tris-buffered saline solution, the addition of glucose increases pH value and promotes pitting corrosion or general corrosion of AZ31 alloy. This study provides a novel perspective to understand the bio-corrosion of Mg alloys in buffering agents and glucose containing solutions.展开更多
High corrosion kinetics and localised corrosion progress are the primary concerns arising from the clinical implementation of magnesium(Mg)based implantable devices.In this study,a binary Mglithium(Li)alloy consisting...High corrosion kinetics and localised corrosion progress are the primary concerns arising from the clinical implementation of magnesium(Mg)based implantable devices.In this study,a binary Mglithium(Li)alloy consisting a record high Li content of 14%(in weight)was employed as model material aiming to yield homogenous and slow corrosion behaviour in a simulated body fluid,i.e.minimum essential medium(MEM),in comparison to that of generic Mg alloy AZ31 and biocompatible Mg-0.5Zn-0.5Ca counterparts.Scanning electron microscopy examination reveals single-phase microstructural characteristics of Mg-14Li(b-Li),whilst the presence of insoluble phases,cathodic to a-Mg matrix,in AZ31 and Mg-0.5Zn-0.5Ca.Though slight differences exist in the corrosion kinetics of all the specimens over a short-term time scale(no longer than 60 min),as indicated by potentiodynamic polarisation and electrochemical impedance spectroscopy,profound variations are apparent in terms of immersion tests,i.e.mass loss and hydrogen evolution measurements(up to 7 days).Cross-sectional micrographs unveil severe pitting corrosion in AZ31 and Mg-0.5Zn-0.5Ca,but not the case for Mg-14Li.X-ray diffraction patterns and X-ray photoelectron spectroscopy confirm that a compact film(25 mm in thickness)consisting of lithium carbonate(Li2CO3)and calcium hydroxide was generated on the surface of Mg-14Li in MEM,which contributes greatly to its low corrosion rate.It is proposed therefore that the single-phase structure and formation of protective and defect-free Li2CO3 film give rise to the controlled and homogenous corrosion behaviour of Mg-14Li in MEM,providing new insights for the exploration of biodegradable Mg materials.展开更多
Effects of NaI as an additive on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl(80-10-10 wt-%)molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry,chronopotentiometry,scanning...Effects of NaI as an additive on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl(80-10-10 wt-%)molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry,chronopotentiometry,scanning electron microscopy and X-ray diffraction(XRD).Results reveal that addition of NaI in the electrolyte intensifies cathodic polarization,inhibits growth of Al deposits and increases number density of charged particles.The electrodeposition of Al coatings in the AlCl_(3)-NaCl-KCl molten salts electrolyte proceeds via three-dimensional instantaneous nucleation which however exhibits irrelevance with NaI.Galvanostatic deposition results indicate that NaI could facilitate the formation of uniform Al deposits.A compact coating consisting of Al deposits with an average particle size of 3μm was obtained at a current density of 50 mA∙cm^(−2) in AlCl_(3)-NaCl-KCl molten salts electrolyte with 10 wt-%NaI.XRD analysis confirmed that NaI could contribute to the formation of Al coating with a preferred crystallographic orientation along(220)plane.展开更多
基金the Ethic Committee of Second Affiliated Hospital of Gannan Medical University。
文摘BACKGROUND Psychological intervention nursing(PIN)has been considered to have a curative effect on cesarean section(CS)post-operative recovery.However,the therapeutic mechanisms remain obscure.AIM To explore the effects of PIN combined with acupressure massage on CS postoperative recovery.METHODS A retrospective study was conducted on 150 pregnant women admitted to an obstetrics department between January 2020 and January 2023.The control group(CG)received acupressure therapy(n=73),and the intervention group(IG)received acupressure therapy and PIN therapy(n=77).Postoperative recovery time was assessed by anal-exhausting,defecation,bed activity,breastfeeding,and hospital stay times.Adverse effects,including infection,bleeding,limb numbness,intrauterine hematoma,urinary retention,and venous thromboembolism,were recorded.the pain visual analogue scale(VAS)was used to evaluate the degree of pain.Anxiety and depression status were qualitatively assessed using the selfrating anxiety scale(SAS),self-rating depression scale(SDS),and Edinburgh postpartum depression scale(EPDS).The Pittsburgh sleep quality index(PSQI)was used to compare sleep quality between the groups.RESULTS The baseline data and SAS,SDS,EPDS,and PSQI scores did not significantly differ before CS(P>0.05)and neither did complication rates between the two groups after CS(P>0.05).However,anal-exhausting,defecation,waking up,breastfeeding,and hospitalization times were significantly shorter for participants in the IG than those for participants in the CG(P<0.05).The VAS,SAS,SDS,EPDS,and PSQI scores of the IG were significantly lower than those of the CG(P<0.05).CONCLUSION PIN,combined with acupressure massage,effectively promotes maternal recovery,reduces post-CS pain,and improves post-operative negative emotions and sleeping quality.
基金This research was financially supported by National Natural Science Foundation of China(51571134)SDUST Research Fund(2014TDJH104).
文摘The clinic applications of bioabsorbable magnesium(Mg)and its alloys have been significantly restricted owing to their poor corrosion resistance.Besides elemental alloying,surface modification and functionality is a major approach to increasing corrosion resistance for magnesium alloys.This article reviews the cutting-edge advances and progress of biodegradable surface coatings upon Mg alloys over the last decades,aims to build up a knowledge framework of surface modification on biodegradable Mg alloys.A considerable number of conversion,deposition,mechanical and functional coatings and their preparation methods are discussed.The emphasis has been placed on the composition of chemical conversion and deposited coatings to overcome the disadvantages of adhesion,corrosion resistance and biocompatibility of a single coating for biomedical materials.The issues have been addressed on the integration of the structural and functional factors of the composite coatings.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 51571134 )the SDUST Re- search Fund ( 2014TDJH104 )the Science and Technol- ogy Innovation Fund of SDUST for graduate students ( SD- KDYC180371 ).
文摘BACKGROUND: Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay and have higher mortality and graft loss rates compared with those without graft dysfunction. However, because of the lack of universally accepted definition, early diagnosis of graft dysfunction is difficult. Additionally, numerous factors affect the allograft function after transplantation, making the prediction of PGD more difficult. The present review was to analyze the literature available on PGD and to propose a definition.DATA SOURCE: A search of PubMed (up to the end of 2012) for English-language articles relevant to PGD was performed to clarify the characteristics, risk factors, and possible treatments or interventions for PGD.RESULTS: There is no pathological diagnostic standard; many documented definitions of PGD are different. Many factors such as donor status, procurement and transplant process and recipient illness may affect the function of graft, and ischemia reperfusion injury is considered the direct cause. Potentia managements which are helpful to improve graft function were investigated. Some of them are promising.CONCLUSIONS: Our analyses suggested that the definition of PGD should include one or more of the following variables: (1)bilirubin ≥10 mg/dL on postoperative day 7; (2) internationa normalized ratio ≥1.6 on postoperative day 7; and (3) alanine aminotransferase or aspartate aminotransferase 】2000 IU/L within 7 postoperative days. Reducing risk factors may decrease the incidence of PGD. A majority of the recipients could recover from PGD; however, when the graft progresses intoprimary non-function, the patients need to be treated with retransplantation.
基金Supported by the National Natural Science Foundation of China, No. 30571759Social Development Foundation of Shanghai, No. 200253
文摘AIM. To investigate the influence of heme oxygenase-1 （HO-1） gene transfer on the viability and function of cultured rat islets in vitro. METHODS： Islets were isolated from the pancreata of Sprague-Dawley rats by intraductal collagenase digestion, and purified by discontinuous Ficoll density gradient centrifugation. Purified rat islets were transfected with adenoviral vectors containing human HO-1 gene （Ad- HO-1） or enhanced green fluorescent protein gene （Ad- EGFP）, and then cultured for seven days. Transfection was confirmed by fluorescence microscopy and Western blot. Islet viability was evaluated by acridine orange/ propidium iodide fluorescent staining. Glucose-stimulated insulin release was detected using insulin radioimmunoassay kits and was used to assess the function of islets. Stimulation index （SI） was calculated by dividing the insulin release upon high glucose stimulation by the insulin release upon low glucose stimulation. RESULTS： After seven days culture, the viability of cultured rat islets decreased significantly （92% ± 6% vs 52% ± 13%, P 〈 0.05）, and glucose-stimulated insulin release also decreased significantly （6.47 ± 0.55 mIU/ L/30IEO vs 4.57 ± 0.40 mIU/L/3OIEO., 14.93 ± 1.17 mIU/L/30IEQ vs 9.63 ± 0.71 mIU/L/30IEQ, P 〈 0.05）. Transfection of rat islets with adenoviral vectors at an 1±10 of 20 was efficient, and did not impair islet function. At 7 d post-transfection, the viability of Ad-HO-1 transfected islets was higher than that of control islets（71% ± 15% vs 52% ± 13%, P 〈 0.05）. There was no significant difference in insulin release upon low glucose stimulation （2.8 mmol/L） among Ad-HO-1 transfected group, Ad-EGFP transfected group, and control group （P 〉 0.05）, while when stimulated by high glucose （16.7 mmol/L） solution, insulin release in Ad-HO-1 transfected group was significantly higher than that in Ad-EGFP transfected group and control group, respectively （12.50 ±2.17 mIU/L/30IEQ vs 8.87 ± 0.65 mIU/L/30IEQ, 12.50 ± 2.17 mIU/L/30IEQ vs 9.63 ± 0.71 mIU/L/30IEQ, P 〈 0.05）. The SI of Ad-HO-1 transfected group was also significantly higher than that of Ad-EGFP transfected group and control group, respectively （2.21 ± 0.02 vs 2.08 ± 0.05; 2.21 ± 0.02 vs 2.11 ± 0.03, P 〈 0.05）. CONCLUSION： The viability and function of rat islets decrease over time in in vitro culture, and heine oxygenase-1 gene transfer could improve the viability and function of cultured rat islets.
基金supported by the National Natural Science Foundation of China (52071191)。
文摘Protein adsorption preferentially occurs and significantly affects the physicochemical reactions once the biodegradable magnesium alloys as bone replacements have been implanted. To date, interactions mechanisms between Mg implants and proteins remain unclear at a molecular level. Thereby, a combination of molecular dynamic(MD) simulations and experimental exploration is used to investigate the adsorption behavior and conformational change of bovine serum albumin(BSA), a representative protein of blood plasma, upon the surface of microarc oxidation(MAO) coated Mg alloy AZ31. The influences of absorbed proteins on the cytocompatibility of MAO coating are evaluated by virtue of cytotoxicity assay. Results indicate that the negatively charged O atoms(BSA) exhibit strong interaction with Mg^(2+) ions of Mg(OH)_(2), revealing that BSA molecules are ionically adsorbed on the AZ31 surface. Interestingly, MD simulation reveals that MAO coating demonstrates superior ability to capture BSA molecules during the process of adsorption owing to strong electric attraction between the negatively charged O atoms in BSA molecules with Mg atoms of MgO in MAO coating. Moreover, the α-helix part of absorbed BSA molecules on AZ31 substrate and MAO coating markedly decreases with an increase in β-sheet, β-turn and unordered contents, which is attributed to the reduction in the number of hydrogen bonds in BSA molecules. Furthermore, the adsorbed BSA molecules improve the cytocompatibility of MAO coating since the positively charged-NH_(3)^(+) group and β-sheet content of absorbed BSA molecules mediate the cell adhesion by interacting with the negatively charged cell membrane.
基金supported by the National Natural Science Foundation of China(21776312)。
文摘The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil,and their catalytic cracking performance was investigated.There are nine classes of basic nitrogen compounds(BNCs)and eleven classes of non-basic heteroatomic compounds(NBHCs)in the different distillates.The dominant BNCs are mainly basic N1 class species.The dominant NBHCs are mainly acidic O2 and O1 class species in the300-350℃,350-400℃,and 400-450℃distillates,while the neutral N1,N1 O1 and N2 compounds become relatively abundant in the>450℃fraction.The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation(different carbon number)but not by aromaticity(different double-bond equivalent values).The basic N1 O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity.After the catalytic cracking of Fushun shale oil,the classes of BNCs in the liquid products remain unchanged,while the classes and relative abundances of NBHCs vary significantly.
基金supported by the National Natural Science Foundation of China(No.52071191)the Open Foundation of Hubei Key Laboratory of Advanced Technology for Automotive Components,China(No.XDQCKF2021006)。
文摘A Schiff base(a compound containing a C=N bond)induced anodic Ca−P coating was prepared on AZ31 Mg alloy in a mixed solution of CaCl_(2) and KH_(2)PO_(4) at 60℃ in the presence of glucose and L-cysteine.The microstructure and chemical composition of the coatings were characterized using FE-SEM,FT-IR,XRD,and XPS.The in vitro degradation resistance of the coated samples was evaluated via potentiodynamic polarization(PDP),electrochemical impedance spectroscopy(EIS),and hydrogen evolution test.The experimental results show that the Ca−PSchiff base coating is composed of CaHPO_(4)(DCPA)and hydroxyapatite(HA),whereas HA is not present in the Ca−P coating.The Ca−P_(Schiff base) coating thickness is about 2 times that of Ca−P coating(Ca−P coating:(9.13±4.20)μm and Ca−P_(Schiff base):(18.13±5.78)μm).The corrosion current density of the Ca−P_(Schiff base) coating is two orders of magnitude lower than that of the Ca−P coating.The formation mechanism of the Ca−P_(Schiff base) is proposed.
文摘BACKGROUND Anastomosis of the testicular vein with the superior mesenteric vein rarely causes severe gastrointestinal bleeding.To date,there have been few studies describing its appearance on medical imaging.Here,we present multidetector computed tomography three-dimensional and multiplanar reconstruction(MPR)images of a typical digital subtraction angiography showing proven ectopic bleeding and provide the first review of the image performance.CASE SUMMARY A 68-year-old man who had been rushed to the hospital with a four-day history of melena and fainting underwent multiple esophagogastroduodenoscopy procedures that failed to identify the source of bleeding.We used MPR combined with three-dimensional reconstruction images,and found that the testicular vein had anastomosed with the superior mesenteric vein,and they clustered together in the jejunal vessel wall,which caused severe gastrointestinal bleeding.Digital subtraction angiography confirmed the location of bleeding.After transfusion and embolization therapy,the patient’s condition improved.CONCLUSION Computed tomography-MPR combined with three-dimensional images offers significant value in the localization and qualitative assessment of rare gastrointestinal hemorrhage.The features of multiphase spiral scanning can improve the accuracy of the diagnosis.
基金National Natural Science Youth Science Foundation No:81300626.
文摘Objective:To study the change of pituitary tumor transforming gene 1 (PTTG1) expression in prostate cancer and its correlation with proliferation and invasion genes.Methods: Patients with prostate cancer who underwent radical operation in our hospital between March 2015 and January 2018 were selected as the malignant group of the research, and the prostate cancer lesions were collected;patients who underwent transurethral resection of the prostate due to benign prostatic hyperplasia in our hospital during the same period were selected as the benign group of the research, and the benign prostate lesions were collected. The mRNA expression levels of PTTG1, proliferation genes and invasion genes in the lesions were determined. Results:PTTG1, Survivin, Bcl-2, CyclinD1, GPRC6A, ZEB1, CatB, CatD and PAR-1 mRNA expression in prostate cancer lesions of malignant group were significantly higher than those of benign group whereas CDKN2, p21 and TFPI2 mRNA expression were significantly lower than those of benign group;Survivin, Bcl-2, CyclinD1, GPRC6A, ZEB1, CatB, CatD and PAR-1 mRNA expression in prostate cancer lesions with high PTTG1 were significantly higher than those in prostate cancer lesions with low PTTG1 whereas CDKN2, p21 and TFPI2 mRNA expression were significantly lower than those in prostate cancer lesions with low PTTG1.Conclusion:The PTTG1 gene is highly expressed in prostate cancer lesions and it is closely related to the changes of proliferation and invasion gene expression.
基金financially supported by the National Natural Science Foundation of China (No.51972109)the Natural Science Foundation of Hunan Province (No.2023JJ30276)+1 种基金the Scientific Research Fund of Hunan Provincial EducationDepartment,China (Nos.22A0473 and 20A225)the Postgraduate Research Innovation Fund of Hunan Institute of Science and Technology (No.2022-38)。
文摘Ingenious establishment of transition metal-nitrogen-carbon electrocatalysts with diverse catalytic active sites and hierarchically porous frameworks is highly significant to boost the oxygen reduction reaction(ORR)in Zn-air batteries(ZABs).In this study,Fe/Co co-doped zeolitic imidazolium frameworks(ZIFs)and graphitic carbon nitride(g-C_(3)N_(4))were integrated and pyrolyzed to construct carbon-based electrocatalysts containing Fe,Co and N elements(labelled as Co-CoFe@NRPC),in which atomic-sc ale FeN_x and CoN_x,and nano scale metallic Co and CoFe alloy moieties were aligned with hierarchically porous N-doped carbon frameworks constructed by interconnected micropolyhedrons,nano tubes and nanosheets.The diverse active moieties guaranteed excellent intrinsic catalytic activity,while the hierarchically porous N-doped carbon frameworks ensured admirable accessibility of the catalytic active sites,excellent electrical conductivity,satisfactory mass transport and good durability.Expectedly,the optimized Co-CoFe@NRPC-90(with 90 mg g-C_(3)N_(4) added)electrocatalyst exhibited excellent ORR performance with a high half-wave potential of 885 mV(vs.reversible hydrogen electrode(RHE)),diffusion-limiting current density of 6.15 mA·cm^(-2),desirable durability and methanol tolerance.Simultaneously,the liquid ZAB established with Co-CoFe@NRPC-90 as an air-cathode electrocatalyst manifested an outstanding power density(281 mW·cm^(-2))and specific capacity(820.9 mAh·g_(Zn)^(-1)),transcending the liquid ZAB based on a commercial Pt/C electrocatalyst.
基金financial support through VC Fellowships and Enabling Capability Platform for Advanced Manufacturing and FabricationFinancial support from the Australian Research Council through DECRA (DE130100090) and Linkage Schemes (LP150100343) is also gratefully acknowledged+2 种基金 support by the National Natural Science Foundation of China (51571134)Shandong University of Science and Technology Research Fund (2014TDJH104)supported by the Natural Science Foundation of the Higher Education Institute of Jiangsu Province (17KJB430003)
文摘Magnesium(Mg) alloys possess comparable physical and mechanical properties to bone, making them an outstanding candidate of implant materials for bone fracture treatment. In addition to the excellent biocompatibility, and bioactivity, the engagement of Mg alloys is key for a number of biological functionalities in the human body. The unique biodegradation nature of Mg alloy implants implies that it may not require a secondary removal procedure when the expected supporting tasks accomplish, as they may simply and safely "disappear" over time. Nonetheless, the demonstrated drawback of potentially rapid degradation, is an issue that must be addressed appropriately for Mg implants and is consequently given unique attention in this review article. Herein, the critical criteria and the state-of-the-art strategies for controlling the degradation process of Mg alloys are reported. Furthermore, future developments of biodegradable Mg and its alloys systems with satisfactory specifications for clinical trials and deployment,are discussed. This review aims to provide information to materials scientists and clinical practitioners in the context of developing practical biodegradable Mg alloys.
基金supported by the National Natural Science Foundation of China(51571134)the SDUST Research Fund(2014TDJH104).
文摘Magnesium(Mg)and its alloys have been widely used in a variety of industrial fields,however,the high corrosion rate and surface contamination restrict their applications.In this study,a corrosion-resistant polymer coating with self-cleaning properties on Mg alloy AZ31 was successfully fabricated via a pretreatment of amino-silane(poly(3-aminopropyl)trimethoxysilane,PAPTMS)and subsequently covered with a polypropylene(PP)film.Surface morphology and chemical compositions were examined using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),and Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS)as well.Contact angle was measured to determine hydrophobicity of the composite coatings.Water permeability of the coatings was evaluated through electrochemical impedance spectroscopy(EIS).Corrosion resistance of the coating was investigated using electrochemical and hydrogen evolution tests.Results indicated that PAPTMS/PP coatings possessed a micrometer-scaled porous spherical microstructure,and super-hydrophobicity with high water contact angle(162±3.4°)and low sliding angle(5±0.6°)due to the low surface energy(10.38 mJ/m2).Moreover,the coating exhibited a smaller water diffusion coefficient(8.12×10-10 cm2/s)and water uptake volume fraction(24.5%),demonstrating low water permeability and good physical barrier performance.As a result,the corrosion current density of PAPTMS/PP coating exhibited approximately three orders of magnitude lower than that of the AZ31 substrate,suggesting excellent corrosion resistance.Finally,corrosion-resistant mechanism of the hybrid coating was proposed.
基金financially supported by the National Natural Science Foundation of China (No.51571134)the Shandong University of Science and Technology Research Fund (No.2014TDJH104)
文摘A hexagonal nanosheet Mg(OH)2 coating was prepared through a one-step hydrothermal method using LiOH solution as mineralizer and then modified by ethylenediaminetetraacetic acid(EDTA) to minimize the rapid corrosion of AZ31 Mg alloy.The performance of the coating was evaluated using electrochemical technique,hydrogen evolution measurements, nanoscratch test,Fourier-transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) patterns and field-emission scanning electron microscopy(FESEM).The results suggested that the corrosion rate of bare AZ31 Mg alloys was significantly reduced by one and two orders of magnitude through the protection from Mg(OH)2 coating and modification with EDTA(i.e., EDTA-Mg(OH)2 coating), respectively.FESEM micrographs indicated that the modification in EDTA elicits to the formation of an EDTA-Mg(OH)2 composite with a thickness as twice as that of as-prepared Mg(OH)2 coating.Nanoscratch tests revealed strong adhesion between the composite or Mg(OH)2 coating and the substrate.The study of formation and corrosion mechanisms of the coatings manifested that Mg(OH)2 was first formed near the intermetallic compound AlMn particles and gradually covered the entire surface, wherein the AlMn particles played an important role in the coating growth process.And it also proved that EDTA accelerated the formation of Mg(OH)2.
基金financially supported by the National Natural Science Foundation of China (Nos.51601108 and 51571134)the Natural Science Foundation of Shandong Province (No. 2016ZRB01A62)+1 种基金the Shandong University of Science and Technology Research Fund (No. 2014TDJH104)the Opening Fund of Ministry-Province Jointly Constructed Cultivation Base for State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials
文摘Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemical compositions and surface morphologies of the coatings were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FESEM). Results indicated that the composite coatings consisted of polymethyltrimethoxysilane (PMTMS), LDH and Mg(OH)2. Electrochemical and hydrogen evolution measurements revealed that the composite coatings possessed good corrosion resistance, especially the ones prepared in a high hydrolysis degree of silane. The optimum corrosion resistance of the composite coati ng was LDH/PMTMS-3 coating, which had the lowest value of corrosion current density (5.537×10^-9 A·cm^-2) and a dense surface.Plausible mechanism for coating formation and corrosion process of MTMS-modified Mg(OH)2/Mg-Al-LDH coatings were discussed.
基金supported by the National Natural Science Foundation of China (No. 50708015)the Program for New Century Excellent Talents in University (No. NCET-06-0270), China
文摘To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 51571134 and 51601108）, the SDUST Research Fund （2014TDJH104） and the Science and Technology Innovation Fund of SDUST for graduate students （SDKDYC180371）.
文摘Biodegradable Mg alloys have generated great interest for biomedical applications. Accurate predictions of in vivo degradation of Mg alloys through costeffective in vitro evaluations require the latter to be conducted in an environment close to that of physiological scenarios. However, the roles of glucose and buffering agents in regulating the in vitro degradation performance of Mg alloys has not been elucidated. Herein, degradation behavior of AZ31 alloy is investigated by hydrogen evolution measurements, pH monitoring and electrochemical tests. Results indicate that glucose plays a content-dependent role in degradation of AZ31 alloy in buffer-free saline solution. The presence of a low concentration of glucose, i.e. 1.0 g/L, decreases the corrosion rate of Mg alloy AZ31, whereas the presence of 2.0 and 3.0 glL glucose accelerates the corrosion rate during long term immersion in saline solution. In terms of Tris-buffered saline solution, the addition of glucose increases pH value and promotes pitting corrosion or general corrosion of AZ31 alloy. This study provides a novel perspective to understand the bio-corrosion of Mg alloys in buffering agents and glucose containing solutions.
基金the financial support from the Australian Research Council(ARC)through Linkage scheme(LP150100343)C.L.is supported by China Scholarship Council(CSC).
文摘High corrosion kinetics and localised corrosion progress are the primary concerns arising from the clinical implementation of magnesium(Mg)based implantable devices.In this study,a binary Mglithium(Li)alloy consisting a record high Li content of 14%(in weight)was employed as model material aiming to yield homogenous and slow corrosion behaviour in a simulated body fluid,i.e.minimum essential medium(MEM),in comparison to that of generic Mg alloy AZ31 and biocompatible Mg-0.5Zn-0.5Ca counterparts.Scanning electron microscopy examination reveals single-phase microstructural characteristics of Mg-14Li(b-Li),whilst the presence of insoluble phases,cathodic to a-Mg matrix,in AZ31 and Mg-0.5Zn-0.5Ca.Though slight differences exist in the corrosion kinetics of all the specimens over a short-term time scale(no longer than 60 min),as indicated by potentiodynamic polarisation and electrochemical impedance spectroscopy,profound variations are apparent in terms of immersion tests,i.e.mass loss and hydrogen evolution measurements(up to 7 days).Cross-sectional micrographs unveil severe pitting corrosion in AZ31 and Mg-0.5Zn-0.5Ca,but not the case for Mg-14Li.X-ray diffraction patterns and X-ray photoelectron spectroscopy confirm that a compact film(25 mm in thickness)consisting of lithium carbonate(Li2CO3)and calcium hydroxide was generated on the surface of Mg-14Li in MEM,which contributes greatly to its low corrosion rate.It is proposed therefore that the single-phase structure and formation of protective and defect-free Li2CO3 film give rise to the controlled and homogenous corrosion behaviour of Mg-14Li in MEM,providing new insights for the exploration of biodegradable Mg materials.
基金The authors would gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant No.51301110)China Postdoctoral Science Foundation(No.2016M600311)Science and Technology Innovation Action Plan—International Enterprises Science and Technology Cooperation Program of Shanghai(No.17230732700).
文摘Effects of NaI as an additive on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl(80-10-10 wt-%)molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry,chronopotentiometry,scanning electron microscopy and X-ray diffraction(XRD).Results reveal that addition of NaI in the electrolyte intensifies cathodic polarization,inhibits growth of Al deposits and increases number density of charged particles.The electrodeposition of Al coatings in the AlCl_(3)-NaCl-KCl molten salts electrolyte proceeds via three-dimensional instantaneous nucleation which however exhibits irrelevance with NaI.Galvanostatic deposition results indicate that NaI could facilitate the formation of uniform Al deposits.A compact coating consisting of Al deposits with an average particle size of 3μm was obtained at a current density of 50 mA∙cm^(−2) in AlCl_(3)-NaCl-KCl molten salts electrolyte with 10 wt-%NaI.XRD analysis confirmed that NaI could contribute to the formation of Al coating with a preferred crystallographic orientation along(220)plane.
