Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) com...Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) compound and NiSO_4(H_2O)(sigma USA) were evaluated by UV visible spectrophotometer.Spectral analysis of L-ascorbic acid and nickel at various pH(2.0, 7.0,7.4 and 8.6) at room temperature of 29℃ was recorded.In this special analysis,combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.Results:The result revealed that λ_(max)(peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 run whereas at neutral pH 7.0,λ_(max) was 29S.4 run.In alkaline pH 8.6,λ_(max) was 295.4 nm and at pH 7.4 the λ_(max) of L-ascorbic acid remained the same as 295.4 nm.Nickel solution at acidic pH 2.0 was 394.5 nm,whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm.But at alkaline pH 8.6,λ_(max) value of nickel sulfate became 392.0 nm.The combined solution of L-ascorbic acid and nickel sulfate(6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm,respectively whereas at pH 7.0,L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm.At pH 7.4,L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6(alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm,respectively. Conclusions:Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH.Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical(HSc*) generation from the reaction of H,ASc + Ni(Ⅱ) is the cause of such alteration of λ_(max),value of L-ascorbic acid in the presence of metal nickel.展开更多
Viscosities and densities at several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations. The parameters of density, viscosity co...Viscosities and densities at several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations. The parameters of density, viscosity coefficient B and partial molar volume are calculated by regression. The experimental results show that densities and viscosities decrease as temperature increases at the same solute and solvent (glucose and sucrose aqueous solution) concentrations, and increase with concentration of glucose and sucrose at the same solute concentration and temperature. B increases with concentration of glucose and sucrose and temperature. L-ascorbic acid is structure-breaker or structure-making for the glucose and sucrose aqueous solutions. Furthermore, the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed.展开更多
In the current studies a miniature silicon wafer fuel cell(FC) using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductiv...In the current studies a miniature silicon wafer fuel cell(FC) using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductively coupled plasma(ICP) silicon etching was employed to fabricate high aspect-ratio columns on the silicon substrate to increase the surface area. A thin platinum layer deposited directly on the silicon surface by the sputtering was used as the catalyst layer for L-ascorbic acid electro-oxidation. Cyclic voltammetry shows that the oxidation of L-ascorbic acid on the sputtered platinum layer is irreversible and that the onset potentials for the oxidation of L-ascorbic acid are from 0.27 V to 0.35 V versus an Ag/AgCl reference electrode. It is found that at the room temperature,with 1 mol/L L-ascorbic acid/PBS(phosphate buffered solution) solution pumped to the anode at 1 ml/min flow rate and air spontaneously diffusing to the cathode as the oxidant,the maximum output power density of the cell was 1.95 mW/cm2 at a current density of 10 mA/cm2.展开更多
L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation....L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation. Microencapsulation is an effective protection technique of L-ascorbic acid from its degradation reactions. This work is focused on the encapsulation of L-ascorbic acid by spray drying technique using sodium alginate as wall material. The microcapsules morphology was observed by scanning electron microscopy (SEM) and the encapsulation efficiency was determined by spectrophotometric analysis. Results showed that encapsulation efficiency was of 93.48% and after 30 days was of 92.55%;differences were not significant, so that the stability of L-ascorbic acid was not affected. Encapsulation yields obtained were low, at around 30%, but the microcapsules morphology obtained is spherical.展开更多
Objective:To study the effect of L-ascorbic acid supplementation on the in vitro development of buffalo embryos and evaluate the relative mRNA abundance of some pro-apoptotic,anti-apoptotic,and embryonic development-r...Objective:To study the effect of L-ascorbic acid supplementation on the in vitro development of buffalo embryos and evaluate the relative mRNA abundance of some pro-apoptotic,anti-apoptotic,and embryonic development-related genes.Methods:In experiment 1,we evaluated the effect of the addition of 0(control),50,and 100μM L-ascorbic acid to the in vitro maturation medium on the developmental competence in terms of blastocyst rate and relative mRNA abundance of some pro-apoptotic(BAX,BID),anti-apoptotic(BCL-XL,MCL1),and embryonic development(GDF9,BMP15)related genes.Based on the results,we chose 50μM as the suitable dose of L-ascorbic acid for the subsequent experiments.We further evaluated the blastocyst rates following the addition of 50μM L-ascorbic acid to the in vitro culture medium(experiment 2),and in vitro maturation and in vitro culture media(experiment 3).In all three experiments,the maturation and culture media devoid of L-ascorbic acid served as the control group.Results:The blastocyst rate after adding 50μM L-ascorbic acid to the in vitro maturation medium was significantly higher than the control group(P<0.05),whereas 100μM L-ascorbic acid exhibited a negative effect on the blastocyst rate.The blastocyst rates for embryos cultured in 50μM L-ascorbic acid in the in vitro culture medium alone and both in vitro maturation and in vitro culture media were significantly higher than their corresponding control groups(P<0.05).The relative mRNA abundance of BAX significantly decreased in blastocysts produced after the addition of 50μM L-ascorbic acid as compared with the control group(P<0.05),whereas,for MCL1,it significantly decreased in blastocysts produced after the addition of 100μM L-ascorbic acid(P<0.05).Conclusions:The supplementation of 50μM L-ascorbic acid to in vitro maturation and in vitro culture media supports in vitro embryonic development in buffaloes by improving developmental competence and altering the expression of apoptosis-related genes.展开更多
The title compound 5,6-O-（4-bromophenyl）-L-ascorbic acid （C13H11BrO6, Mr = 343.13） has been synthesized and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The product is a mixt...The title compound 5,6-O-（4-bromophenyl）-L-ascorbic acid （C13H11BrO6, Mr = 343.13） has been synthesized and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The product is a mixture of two diastereomer compounds （a （7S） and b （7R））. The crystal of a （7S） belongs to orthorhombic system, space group P212121 with a = 6.5362（10）, b = 7.8226（11）, c = 25.294（4） ？, V = 1293.3（3） ？3, Z = 4, Dc = 1.762 g/cm3, μ（MoKα） = 3.202 mm-1, F（000） = 688, R = 0.0235 and wR （I 〉 2σ（I）） = 0.0566. The hydrogen bonding interactions link the molecules to form a three-dimensional system. In addition, 5,6-O-（4-bromophenyl）-L-ascorbic acid （BPAA） exhibits strong free-radical scavenging activities in vitro against 2,2-diphenyl-1-picrylhy- drazyl and superoxide anion. BPAA should be investigated further as a worthy antioxidant.展开更多
A small focused library which comprised of L-AA lactone derivatives was built with a facile method.This reported method was optimized by modifying the acidity of the solvent.As a result,12 L-AA lactones were synthesiz...A small focused library which comprised of L-AA lactone derivatives was built with a facile method.This reported method was optimized by modifying the acidity of the solvent.As a result,12 L-AA lactones were synthesized.Among these lactones,lactones 8–12 were new compounds.The cytotoxicity of these synthetic compounds were investigated.展开更多
Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyr...Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.展开更多
The fruit of chestnut rose(Rosa roxburghii Tratt.)contains exceptionally high levels of L-ascorbic acid(AsA)(∼1762 mg/100 g fresh weight),approximately 40-fold higher than those found in sweet orange(Citrus sinensis)...The fruit of chestnut rose(Rosa roxburghii Tratt.)contains exceptionally high levels of L-ascorbic acid(AsA)(∼1762 mg/100 g fresh weight),approximately 40-fold higher than those found in sweet orange(Citrus sinensis),which is well known for its high AsA content.However,the molecular mechanisms driving such high accumulation in chestnut rose remain unclear.Here,we report that the genes R.roxburghii PECTIN METHYLESTERASE(RroxPME),D-GALACTURONATE REDUCTASE(RroxGalUR),and DEHYDROASCORBATE REDUCTASE 2(RroxDHAR2)play crucial roles in AsA accumulation in chestnut rose fruit.By comparing R.roxburghii with the closely related Rosa multiflora,which has low AsA concentrations,we identified a 545-bp insertion in the promoter of RroxGalUR.We found that TRANSPARENT TESTA GLABRA 2(RroxTTG2),a well-known key regulator of trichome development,binds to the W-box-containing inserted region of the RroxGalUR promoter as well as the promoters of RroxPME and RroxDHAR2.In contrast,in sweet orange,CsTTG2 can bind only to CsPME.Furthermore,RroxTTG2 retains its conserved role in the regulation of trichome development during early fruit development,suggesting its spatiotemporal specificity in regulating both trichome development and AsA biosynthesis.To evaluate the application value of this pathway in other species,we heterologously expressed RroxTTG2,RroxPME,RroxGalUR,and RroxDHAR2 in lettuce(Lactuca sativa L.),which increased AsA concentrations in the transgenic lines by up to 355%(an increase from approximately 2 to 10 mg/100 g fresh weight).This study provides insights into mechanisms underlying AsA accumulation in chestnut rose and the spatiotemporal transcriptional regulation of AsA biosynthesis and trichome development.展开更多
Recent studies have highlighted the effects of various stimuli on the chemical reduction of graphene oxide(GO)through green reductant L-ascorbic acid(L-AA);however,the combination of near ultraviolet(NUV)light to incr...Recent studies have highlighted the effects of various stimuli on the chemical reduction of graphene oxide(GO)through green reductant L-ascorbic acid(L-AA);however,the combination of near ultraviolet(NUV)light to increase the reduction rate has yet to be thoroughly explored.In this study,drop-casted GO films were subjected to chemical reduction through L-AA with various levels of exposure under 405 nm NUV radiation.The structure and uniformity of GO stackings that form the film were characterized through scanning electron microscopy(SEM)and wide-angle x-ray scattering(WAXS).Additionally,WAXS was used to track the removal of oxygen-containing functional groups along with Fourier-transform infrared(FT-IR)spectroscopy and x-ray photoelectron spectroscopy(XPS)as a function of L-AA and NUV light exposure times.XPS results demonstrated that the interaction between L-AA and NUV exposure has a significant effect on the reduction of films.Furthermore,the results that yielded the highest reduction(C-C bond concentration of 60.7%)were the longest L-AA and NUV light exposure times(48 hours and 3 hours,respectively).This report provides a study on the effects of NUV on the green reduction of GO films through L-AA with potential application in solar energy and chemical sensing applications.展开更多
Retinoic acid(RA)and 2-phospho-L-ascorbic acid trisodium salt(AscPNa)promote the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells.In the current studies,the lower abilities of RA and AscP...Retinoic acid(RA)and 2-phospho-L-ascorbic acid trisodium salt(AscPNa)promote the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells.In the current studies,the lower abilities of RA and AscPNa to promote reprogramming in the presence of each other suggested that they may share downstream pathways at least partially.The hypothesis was further supported by the RNA-seq analysis which demonstrated a high-level overlap between RA-activated and AscPNa activated genes during reprogramming.In addition,RA upregulated Glut1/3,facilitated the membrane transportation of dehydroascorbic acid,the oxidized form of L-ascorbic acid,and subsequently maintained intracellular L-ascorbic acid at higher level and for longer time.On the other hand,AscPNa facilitated the mesenchymal-epithelial transition during reprogramming,downregulated key mesenchymal transcriptional factors like Zeb1 and Twist1,subsequently suppressed the expression of Cyp26a1/b1 which mediates the metabolism of RA,and sustained the intracellular level of RA.Furthermore,the different abilities of RA and AscPNa to induce mesenchymal-epithelial transition,pluripotency,and neuronal differentiation explain their complex contribution to reprogramming when used individually or in combination.Therefore,the current studies identified a positive feedback between RA and AscPNa,or possibility between vitamin A and C,and further explored their contributions to reprogramming.展开更多
BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive...BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.展开更多
Maintaining high metal dispersion of supported metal catalysts to achieve superior reactivity under harsh conditions poses one of the main challenges for their practical applications.Constructing and regulating the st...Maintaining high metal dispersion of supported metal catalysts to achieve superior reactivity under harsh conditions poses one of the main challenges for their practical applications.Constructing and regulating the strong metal-support interactions(SMSI)by diverse methodologies has emerged as one of the promising approaches to fabricating robust supported metal catalysts.In this study,we report an L-ascorbic acid(AA)-inducing strategy to generate SMSI on a titania-supported gold(Au)catalyst after high-temperature treatment in an inert atmosphere(600℃,N_(2)).The AA-induced SMSI can efficiently stabilize Au nanoparticles(NPs)and preserve their catalytic performance.The detailed study reveals that the key to realizing this SMSI is the generation of oxygen vacancies within the TiO_(2) support induced by the adsorbed AA,which drives the formation of the Ti Oxpermeable layer onto the Au NPs.The strategy could be extended to TiO_(2)-supported Au catalysts with different crystal phases and platinum group metals,such as Pt,Pd,and Rh.This work offers a promising novel route to design stable and efficient supported noble metal catalysts by constructing SMSI using simple reducing organic adsorbent.展开更多
Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solve...Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.展开更多
Objective:To improvein vitro embryo production in buffalo by supplementation of L-ascorbic acid during maturation and development (experiment 1) and combination with another antioxidant as cysteamine (experiment 2).Me...Objective:To improvein vitro embryo production in buffalo by supplementation of L-ascorbic acid during maturation and development (experiment 1) and combination with another antioxidant as cysteamine (experiment 2).Methods:Two experiments were performed, the first one aimed to evaluate the different concentrations (0, 25, 50, 100 μM) of L-ascorbic acid on embryo developmental rate of buffalo oocytes. The L-ascorbic acid was added to the maturation and culture media. In the second experiment, oocytes were cultured in media with two type of antioxidant (ascorbic acid + cysteamine) or ascorbic acid only.Results:There was a significant increase in cleavage rate at 25, 50 μM than 100 μM and control group. But, the blastocyst rate was higher at 50 μM ascorbic acid than other concentrations (0, 25, 100 μM). Supplementation of ascorbic acid and cysteamine to maturation and cultured media improved embryo development than ascorbic acid alone.Conclusions: Using of 50 μM L-ascorbic acid duringin vitro maturation and development improve the developmental competence of buffalo oocytes, this effect was increase with the presence of cysteamine.展开更多
L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding...L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding GMP in soybean and here we report genetic and functional analysis of the GmGMP1 （Glycine max GDP-D-mannose pyrophosphorylase 1） gene in this species. GmGMP1 encoded a GDP-mannose pyrophosphorylase and exhibited higher transcript levels in the leaf than in the root, stem, flower, and seed. Transcript of this gene was ubiquitous in the vegetative and reproductive organs, and was induced by abiotic stress and light. Increasing expression of GmGMP1 in Arabidopsis and soybean through an overexpressing approach caused pronounced enhancement of AsA content, and was implicated in lowering the superoxide anion radical content and lipid peroxidation levels in Arabidopsis, and conferring tolerance to osmotic and high salt stresses during seed germination. The present study represents the first systematic determination of soybean genes encoding GDP-mannose pyrophosphorylase and provides useful evidence for the functional involvement of GmGMP1 in control of AsA content and conferring tolerance to osmotic and salt stress.展开更多
L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10-5 to 4.5 × 10-4 mol/L was studied using cyclic ...L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10-5 to 4.5 × 10-4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy.Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation,with the poisoning effect of polysulfide ion being more pronounced in the potential range of-0.3 to-0.2 V/SCE.The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were,10-3 to 1 × 10-2 s and 1 × 10-4 to 1 × 10-2 s,respectively depending on the potential used for the impedance analysis.Based on the cyclic voltammetry findings,a mechanism for L-ascorbate oxidation in the presence of polysulfide ions was proposed.Impedance calculations based on the kinetic analysis can account for the occurrence of a negative impedance in a potential region around-0.2 V/SCE in the Nyquist polts.展开更多
We recently reported that L-ascorbic acid 2-phosphate (AP) stimulates the growth of human dermal papilla (DP) cells, induces secretion of IGF-1 from the DP cells to promote hair shafts elongation in cultured human hai...We recently reported that L-ascorbic acid 2-phosphate (AP) stimulates the growth of human dermal papilla (DP) cells, induces secretion of IGF-1 from the DP cells to promote hair shafts elongation in cultured human hair follicles, and triggers early progression from the telogen to anagen phase in mice. Since the magnesium salt of AP (APMg) is a highly hydrophilic ionic molecule, it is not easy to deliver this reagent to the skin or hair follicles by topical application alone. In order to enhance skin penetration of APMg without changing any molecular properties, a non-invasive iontophoretic delivery method was introduced. Iontophoresis of the negatively charged APMg under the electrode bearing same charge (cathode) significantly enhanced the in vitro penetration of APMg into a Franz cell equipped with mouse dorsal skin. In contrast, iontophoretic movement with the anode inhibited APMg penetration achieved with passive diffusion alone. The effect of iontophoresis on enhancing the penetration of APMg was also found to be much higher in the skin of hairy mice (3 - 8 times) compared to hairless mice (1.5 - 2.5 times). These findings indicated that iontophoretic movement induced the transfollicular pathway more strongly and effectively than the transdermal pathway. This phenomena was also demonstrated by the in vivo iontophoretic delivery of sodium fluorescein using hairy and hairless mice. The degree of iontophoretic enhancement during APMg penetration was also dependent on various conditions such as current density and application duration.展开更多
Lactobacillus crispatus is a commonly found species in the urogenital tract(UGT)of healthy females and can also colonize other niches,such as the gastrointestinal tract(GIT).Although its potential protective role in c...Lactobacillus crispatus is a commonly found species in the urogenital tract(UGT)of healthy females and can also colonize other niches,such as the gastrointestinal tract(GIT).Although its potential protective role in cervical cancer has been reported,the anticancer mechanisms involved are still unclear.In this study,we sequenced and characterized the complete genomes of two L.crispatus strains(Lc31 and Lc83)isolated from the UGT of healthy women of reproductive age.Phylogenetic and phylogenomic analyses of these two strains and 15 other L.crispatus strains with complete genome sequences revealed that strains from the UGT and GIT clustered separately.UGT strains had a larger genome size,higher GC contents,and more protein-coding sequences and insertion sequence(Is)elements,indicating the likelihood of active horizontal gene transfer in this niche.We found a universal presence of genes encoding bacteriocins and the absence of virulence factors and antibiotic resistance genes in UGT strains,suggesting the potential of L.crispatus as a urogenital probiotic.Comparative genomic analysis identified an ula gene cluster responsible for L-ascorbate catabolism exclusively in UGT strains,and carbohydrate fermentation experiments confirmed that this substrate supported the growth of L.crispatus Lc31 and Lc83.Our findings improve the understanding of how the genome determines niche adaptation by L.crispatus,providing a foundation for investigating the mechanisms by which urogenital-derived L.crispatus promotes female health.展开更多
The development of an active, durable, and metal-free carbocatalyst that is able to replace metal-based catalysts is of increasing scientific and technological importance. The use of such a catalyst would avoid proble...The development of an active, durable, and metal-free carbocatalyst that is able to replace metal-based catalysts is of increasing scientific and technological importance. The use of such a catalyst would avoid problems caused by metal- containing catalysts, for example, environmental pollution by heavy metals and depletion of rare metal resources. Herein, an active and durable graphene carbocatalyst is presented for the carbocatalytic conversion of 4-nitrophenol to 4-aminophenol at ambient temperature. The carbocatalyst was prepared via a mild, water-based reaction between L-ascorbic acid （AA） and graphene oxide （GO） and did not involve any other reactants. During the structure and catalytic property optimization, a series of carbocatalysts were fabricated at various reaction temperatures and AA/GO ratios. Using several characterization techniques, detailed structural features of these carbocatalysts were identified. Possible active species and sites on the carbocatalysts were also identified such as certain oxygen-containing groups, the ~x-conjugated system, and graphene sheet edges. In addition, the synergistic effect between these active species and sites on the resulting catalytic activity is highlighted. Furthermore, we clarified the origin of the high stability and durability of the optimized carbocatalyst. The work presented here aids the design of high-performance carbocatalysts for hydrogenation reactions, and increases understanding of the structural and mechanistic aspects at the molecular level that lead to high catalyst activity and durability.展开更多
基金financially supported by Defence Institute ofPhysiology and Allied Sciences,Government of India,New Delhi[grant No.TC/292/TASK-116(KDS)/DIPAS/2006]
文摘Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) compound and NiSO_4(H_2O)(sigma USA) were evaluated by UV visible spectrophotometer.Spectral analysis of L-ascorbic acid and nickel at various pH(2.0, 7.0,7.4 and 8.6) at room temperature of 29℃ was recorded.In this special analysis,combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.Results:The result revealed that λ_(max)(peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 run whereas at neutral pH 7.0,λ_(max) was 29S.4 run.In alkaline pH 8.6,λ_(max) was 295.4 nm and at pH 7.4 the λ_(max) of L-ascorbic acid remained the same as 295.4 nm.Nickel solution at acidic pH 2.0 was 394.5 nm,whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm.But at alkaline pH 8.6,λ_(max) value of nickel sulfate became 392.0 nm.The combined solution of L-ascorbic acid and nickel sulfate(6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm,respectively whereas at pH 7.0,L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm.At pH 7.4,L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6(alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm,respectively. Conclusions:Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH.Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical(HSc*) generation from the reaction of H,ASc + Ni(Ⅱ) is the cause of such alteration of λ_(max),value of L-ascorbic acid in the presence of metal nickel.
基金Supported by the Educational Department Doctor Foundation of China(No.2000005608).
文摘Viscosities and densities at several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations. The parameters of density, viscosity coefficient B and partial molar volume are calculated by regression. The experimental results show that densities and viscosities decrease as temperature increases at the same solute and solvent (glucose and sucrose aqueous solution) concentrations, and increase with concentration of glucose and sucrose at the same solute concentration and temperature. B increases with concentration of glucose and sucrose and temperature. L-ascorbic acid is structure-breaker or structure-making for the glucose and sucrose aqueous solutions. Furthermore, the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed.
基金the National Natural Science Foundation of China (No. 30670535)the Program for New Century Excellent Talents in University (No. NCET-07-0752), China
文摘In the current studies a miniature silicon wafer fuel cell(FC) using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductively coupled plasma(ICP) silicon etching was employed to fabricate high aspect-ratio columns on the silicon substrate to increase the surface area. A thin platinum layer deposited directly on the silicon surface by the sputtering was used as the catalyst layer for L-ascorbic acid electro-oxidation. Cyclic voltammetry shows that the oxidation of L-ascorbic acid on the sputtered platinum layer is irreversible and that the onset potentials for the oxidation of L-ascorbic acid are from 0.27 V to 0.35 V versus an Ag/AgCl reference electrode. It is found that at the room temperature,with 1 mol/L L-ascorbic acid/PBS(phosphate buffered solution) solution pumped to the anode at 1 ml/min flow rate and air spontaneously diffusing to the cathode as the oxidant,the maximum output power density of the cell was 1.95 mW/cm2 at a current density of 10 mA/cm2.
文摘L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation. Microencapsulation is an effective protection technique of L-ascorbic acid from its degradation reactions. This work is focused on the encapsulation of L-ascorbic acid by spray drying technique using sodium alginate as wall material. The microcapsules morphology was observed by scanning electron microscopy (SEM) and the encapsulation efficiency was determined by spectrophotometric analysis. Results showed that encapsulation efficiency was of 93.48% and after 30 days was of 92.55%;differences were not significant, so that the stability of L-ascorbic acid was not affected. Encapsulation yields obtained were low, at around 30%, but the microcapsules morphology obtained is spherical.
基金funded by the National Agriculture Innovation Project Grant to Suresh Kumar Singla(C 2-1-(5)/2007)Manmohan Singh Chauhan(C-2067 and 075).
文摘Objective:To study the effect of L-ascorbic acid supplementation on the in vitro development of buffalo embryos and evaluate the relative mRNA abundance of some pro-apoptotic,anti-apoptotic,and embryonic development-related genes.Methods:In experiment 1,we evaluated the effect of the addition of 0(control),50,and 100μM L-ascorbic acid to the in vitro maturation medium on the developmental competence in terms of blastocyst rate and relative mRNA abundance of some pro-apoptotic(BAX,BID),anti-apoptotic(BCL-XL,MCL1),and embryonic development(GDF9,BMP15)related genes.Based on the results,we chose 50μM as the suitable dose of L-ascorbic acid for the subsequent experiments.We further evaluated the blastocyst rates following the addition of 50μM L-ascorbic acid to the in vitro culture medium(experiment 2),and in vitro maturation and in vitro culture media(experiment 3).In all three experiments,the maturation and culture media devoid of L-ascorbic acid served as the control group.Results:The blastocyst rate after adding 50μM L-ascorbic acid to the in vitro maturation medium was significantly higher than the control group(P<0.05),whereas 100μM L-ascorbic acid exhibited a negative effect on the blastocyst rate.The blastocyst rates for embryos cultured in 50μM L-ascorbic acid in the in vitro culture medium alone and both in vitro maturation and in vitro culture media were significantly higher than their corresponding control groups(P<0.05).The relative mRNA abundance of BAX significantly decreased in blastocysts produced after the addition of 50μM L-ascorbic acid as compared with the control group(P<0.05),whereas,for MCL1,it significantly decreased in blastocysts produced after the addition of 100μM L-ascorbic acid(P<0.05).Conclusions:The supplementation of 50μM L-ascorbic acid to in vitro maturation and in vitro culture media supports in vitro embryonic development in buffaloes by improving developmental competence and altering the expression of apoptosis-related genes.
基金financially supported by the Scientific Research Fund of Hunan Provincial Education Department(No.16B104)the Opening Project of Key Laboratory of Comprehensive Utilization of Advantage Plants Resources in Hunan South(No.XNZW16C01)the Scientific Research Fund of Hunan University of Science and Engineering(No.16XKY063)
文摘The title compound 5,6-O-（4-bromophenyl）-L-ascorbic acid （C13H11BrO6, Mr = 343.13） has been synthesized and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The product is a mixture of two diastereomer compounds （a （7S） and b （7R））. The crystal of a （7S） belongs to orthorhombic system, space group P212121 with a = 6.5362（10）, b = 7.8226（11）, c = 25.294（4） ？, V = 1293.3（3） ？3, Z = 4, Dc = 1.762 g/cm3, μ（MoKα） = 3.202 mm-1, F（000） = 688, R = 0.0235 and wR （I 〉 2σ（I）） = 0.0566. The hydrogen bonding interactions link the molecules to form a three-dimensional system. In addition, 5,6-O-（4-bromophenyl）-L-ascorbic acid （BPAA） exhibits strong free-radical scavenging activities in vitro against 2,2-diphenyl-1-picrylhy- drazyl and superoxide anion. BPAA should be investigated further as a worthy antioxidant.
基金This work was financially supported by the National Natural Science Foundation of China(No.U0932602)the National Basic Research Program of China(973 Program No.2011CB915503).
文摘A small focused library which comprised of L-AA lactone derivatives was built with a facile method.This reported method was optimized by modifying the acidity of the solvent.As a result,12 L-AA lactones were synthesized.Among these lactones,lactones 8–12 were new compounds.The cytotoxicity of these synthetic compounds were investigated.
文摘Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.
基金supported by a National Natural Science Foundation of China grant to Q.X.(nos.32494781 and 32525008)the Key Project of Hubei Provincial Natural Science Foundation grant to Q.X.(2025AFA006)+1 种基金the Foundation of Hubei Hongshan Laboratory grants to Q.X.and X.W.(nos.2021hszd016 and 2022hsqd010,respectively)a National Natural Science Foundation of China Youth Science Fund grant to G.L.(no.32302490).
文摘The fruit of chestnut rose(Rosa roxburghii Tratt.)contains exceptionally high levels of L-ascorbic acid(AsA)(∼1762 mg/100 g fresh weight),approximately 40-fold higher than those found in sweet orange(Citrus sinensis),which is well known for its high AsA content.However,the molecular mechanisms driving such high accumulation in chestnut rose remain unclear.Here,we report that the genes R.roxburghii PECTIN METHYLESTERASE(RroxPME),D-GALACTURONATE REDUCTASE(RroxGalUR),and DEHYDROASCORBATE REDUCTASE 2(RroxDHAR2)play crucial roles in AsA accumulation in chestnut rose fruit.By comparing R.roxburghii with the closely related Rosa multiflora,which has low AsA concentrations,we identified a 545-bp insertion in the promoter of RroxGalUR.We found that TRANSPARENT TESTA GLABRA 2(RroxTTG2),a well-known key regulator of trichome development,binds to the W-box-containing inserted region of the RroxGalUR promoter as well as the promoters of RroxPME and RroxDHAR2.In contrast,in sweet orange,CsTTG2 can bind only to CsPME.Furthermore,RroxTTG2 retains its conserved role in the regulation of trichome development during early fruit development,suggesting its spatiotemporal specificity in regulating both trichome development and AsA biosynthesis.To evaluate the application value of this pathway in other species,we heterologously expressed RroxTTG2,RroxPME,RroxGalUR,and RroxDHAR2 in lettuce(Lactuca sativa L.),which increased AsA concentrations in the transgenic lines by up to 355%(an increase from approximately 2 to 10 mg/100 g fresh weight).This study provides insights into mechanisms underlying AsA accumulation in chestnut rose and the spatiotemporal transcriptional regulation of AsA biosynthesis and trichome development.
基金This work was supported by the National Nuclear Security Administration[DE-NA-0003865]National Science Foundation[1848741,HRD-1810898].
文摘Recent studies have highlighted the effects of various stimuli on the chemical reduction of graphene oxide(GO)through green reductant L-ascorbic acid(L-AA);however,the combination of near ultraviolet(NUV)light to increase the reduction rate has yet to be thoroughly explored.In this study,drop-casted GO films were subjected to chemical reduction through L-AA with various levels of exposure under 405 nm NUV radiation.The structure and uniformity of GO stackings that form the film were characterized through scanning electron microscopy(SEM)and wide-angle x-ray scattering(WAXS).Additionally,WAXS was used to track the removal of oxygen-containing functional groups along with Fourier-transform infrared(FT-IR)spectroscopy and x-ray photoelectron spectroscopy(XPS)as a function of L-AA and NUV light exposure times.XPS results demonstrated that the interaction between L-AA and NUV exposure has a significant effect on the reduction of films.Furthermore,the results that yielded the highest reduction(C-C bond concentration of 60.7%)were the longest L-AA and NUV light exposure times(48 hours and 3 hours,respectively).This report provides a study on the effects of NUV on the green reduction of GO films through L-AA with potential application in solar energy and chemical sensing applications.
基金This work was supported by the National Natural Science Foundation of China(Grant No.31671475,U1601228,31900699,and 81702445)the Strategic Priority Research Program of Chinese Academy of Sciences,No.XDA16010305+3 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences,No.QYZDB-SSW-SMC031the International Partnership Program of Chinese Academy of Sciences,No.154144KYSB20190034the Key Research&Development Program of Guangzhou Regenerative Medicine and Health Guangdong Laboratory(Grant No.2018GZR110104008)the Science and Technology Planning Project of Guangdong Province(Grant No.2017B030314056)。
文摘Retinoic acid(RA)and 2-phospho-L-ascorbic acid trisodium salt(AscPNa)promote the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells.In the current studies,the lower abilities of RA and AscPNa to promote reprogramming in the presence of each other suggested that they may share downstream pathways at least partially.The hypothesis was further supported by the RNA-seq analysis which demonstrated a high-level overlap between RA-activated and AscPNa activated genes during reprogramming.In addition,RA upregulated Glut1/3,facilitated the membrane transportation of dehydroascorbic acid,the oxidized form of L-ascorbic acid,and subsequently maintained intracellular L-ascorbic acid at higher level and for longer time.On the other hand,AscPNa facilitated the mesenchymal-epithelial transition during reprogramming,downregulated key mesenchymal transcriptional factors like Zeb1 and Twist1,subsequently suppressed the expression of Cyp26a1/b1 which mediates the metabolism of RA,and sustained the intracellular level of RA.Furthermore,the different abilities of RA and AscPNa to induce mesenchymal-epithelial transition,pluripotency,and neuronal differentiation explain their complex contribution to reprogramming when used individually or in combination.Therefore,the current studies identified a positive feedback between RA and AscPNa,or possibility between vitamin A and C,and further explored their contributions to reprogramming.
基金Supported by National Key Research and Development Program of China,No.2021YFA1100600 and No.2022YFA1104400.
文摘BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.
基金supported by the National Natural Science Foundation of China(NSFC)the Japan Society for the Promotion of Science(JSPS)under the Joint Research Program(Nos.NSFC21961142006 and JPJSJRP20191804)+3 种基金NSFC(Nos.U22A20394 and 22375200)the DICP.CAS-Cardiff Joint Research Units(No.121421ZYLH20230008)the International Partnership Program of Chinese Academy of Sciences(No.028GJHZ2023097GC)the China Postdoctoral Science Foundation(No.2022M723086)。
文摘Maintaining high metal dispersion of supported metal catalysts to achieve superior reactivity under harsh conditions poses one of the main challenges for their practical applications.Constructing and regulating the strong metal-support interactions(SMSI)by diverse methodologies has emerged as one of the promising approaches to fabricating robust supported metal catalysts.In this study,we report an L-ascorbic acid(AA)-inducing strategy to generate SMSI on a titania-supported gold(Au)catalyst after high-temperature treatment in an inert atmosphere(600℃,N_(2)).The AA-induced SMSI can efficiently stabilize Au nanoparticles(NPs)and preserve their catalytic performance.The detailed study reveals that the key to realizing this SMSI is the generation of oxygen vacancies within the TiO_(2) support induced by the adsorbed AA,which drives the formation of the Ti Oxpermeable layer onto the Au NPs.The strategy could be extended to TiO_(2)-supported Au catalysts with different crystal phases and platinum group metals,such as Pt,Pd,and Rh.This work offers a promising novel route to design stable and efficient supported noble metal catalysts by constructing SMSI using simple reducing organic adsorbent.
基金supported by the National Natural Science Foundation of China(Grant No.51802181)Natural Science Basic Research Program of Shaanxi(Grant No.2022JZ-31)+3 种基金Young Talent fund of University Association for Science and Technology in Shaanxi,China(Grant No.20210411)China Postdoctoral Sci-ence Foundation(Grant No.2021M692621)the Foundation of Shaanxi University of Science&Technology(Grant No.2017GBJ-03)ZGC thanks the financial support from the Australian Research Council,QUT capacity building professor program,and HBIS-UQ In-novation center for Sustainable Steel(ICSS)project.
文摘Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.
文摘Objective:To improvein vitro embryo production in buffalo by supplementation of L-ascorbic acid during maturation and development (experiment 1) and combination with another antioxidant as cysteamine (experiment 2).Methods:Two experiments were performed, the first one aimed to evaluate the different concentrations (0, 25, 50, 100 μM) of L-ascorbic acid on embryo developmental rate of buffalo oocytes. The L-ascorbic acid was added to the maturation and culture media. In the second experiment, oocytes were cultured in media with two type of antioxidant (ascorbic acid + cysteamine) or ascorbic acid only.Results:There was a significant increase in cleavage rate at 25, 50 μM than 100 μM and control group. But, the blastocyst rate was higher at 50 μM ascorbic acid than other concentrations (0, 25, 100 μM). Supplementation of ascorbic acid and cysteamine to maturation and cultured media improved embryo development than ascorbic acid alone.Conclusions: Using of 50 μM L-ascorbic acid duringin vitro maturation and development improve the developmental competence of buffalo oocytes, this effect was increase with the presence of cysteamine.
基金supported by the Genetically Modified Organisms Breeding Major Projects, China (2016ZX08004)the earmarked fund for China Agriculture Research System (CARS-004-PS10)the Program for Changjiang Scholars and Innovative Research Team in University, China (PCSIRT13073)
文摘L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding GMP in soybean and here we report genetic and functional analysis of the GmGMP1 （Glycine max GDP-D-mannose pyrophosphorylase 1） gene in this species. GmGMP1 encoded a GDP-mannose pyrophosphorylase and exhibited higher transcript levels in the leaf than in the root, stem, flower, and seed. Transcript of this gene was ubiquitous in the vegetative and reproductive organs, and was induced by abiotic stress and light. Increasing expression of GmGMP1 in Arabidopsis and soybean through an overexpressing approach caused pronounced enhancement of AsA content, and was implicated in lowering the superoxide anion radical content and lipid peroxidation levels in Arabidopsis, and conferring tolerance to osmotic and high salt stresses during seed germination. The present study represents the first systematic determination of soybean genes encoding GDP-mannose pyrophosphorylase and provides useful evidence for the functional involvement of GmGMP1 in control of AsA content and conferring tolerance to osmotic and salt stress.
基金supported by the office of vice chancellor of research of Sharif University of Technology
文摘L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10-5 to 4.5 × 10-4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy.Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation,with the poisoning effect of polysulfide ion being more pronounced in the potential range of-0.3 to-0.2 V/SCE.The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were,10-3 to 1 × 10-2 s and 1 × 10-4 to 1 × 10-2 s,respectively depending on the potential used for the impedance analysis.Based on the cyclic voltammetry findings,a mechanism for L-ascorbate oxidation in the presence of polysulfide ions was proposed.Impedance calculations based on the kinetic analysis can account for the occurrence of a negative impedance in a potential region around-0.2 V/SCE in the Nyquist polts.
文摘We recently reported that L-ascorbic acid 2-phosphate (AP) stimulates the growth of human dermal papilla (DP) cells, induces secretion of IGF-1 from the DP cells to promote hair shafts elongation in cultured human hair follicles, and triggers early progression from the telogen to anagen phase in mice. Since the magnesium salt of AP (APMg) is a highly hydrophilic ionic molecule, it is not easy to deliver this reagent to the skin or hair follicles by topical application alone. In order to enhance skin penetration of APMg without changing any molecular properties, a non-invasive iontophoretic delivery method was introduced. Iontophoresis of the negatively charged APMg under the electrode bearing same charge (cathode) significantly enhanced the in vitro penetration of APMg into a Franz cell equipped with mouse dorsal skin. In contrast, iontophoretic movement with the anode inhibited APMg penetration achieved with passive diffusion alone. The effect of iontophoresis on enhancing the penetration of APMg was also found to be much higher in the skin of hairy mice (3 - 8 times) compared to hairless mice (1.5 - 2.5 times). These findings indicated that iontophoretic movement induced the transfollicular pathway more strongly and effectively than the transdermal pathway. This phenomena was also demonstrated by the in vivo iontophoretic delivery of sodium fluorescein using hairy and hairless mice. The degree of iontophoretic enhancement during APMg penetration was also dependent on various conditions such as current density and application duration.
基金supported by grants from the Natural Science Foundation of Anhui Province(grant number 2208085MH253)the National Natural Science Foundation(grant number 81702560)the Fundamental Research Funds for the Central Universities(grant number WK9110000110),People's Republic of China.
文摘Lactobacillus crispatus is a commonly found species in the urogenital tract(UGT)of healthy females and can also colonize other niches,such as the gastrointestinal tract(GIT).Although its potential protective role in cervical cancer has been reported,the anticancer mechanisms involved are still unclear.In this study,we sequenced and characterized the complete genomes of two L.crispatus strains(Lc31 and Lc83)isolated from the UGT of healthy women of reproductive age.Phylogenetic and phylogenomic analyses of these two strains and 15 other L.crispatus strains with complete genome sequences revealed that strains from the UGT and GIT clustered separately.UGT strains had a larger genome size,higher GC contents,and more protein-coding sequences and insertion sequence(Is)elements,indicating the likelihood of active horizontal gene transfer in this niche.We found a universal presence of genes encoding bacteriocins and the absence of virulence factors and antibiotic resistance genes in UGT strains,suggesting the potential of L.crispatus as a urogenital probiotic.Comparative genomic analysis identified an ula gene cluster responsible for L-ascorbate catabolism exclusively in UGT strains,and carbohydrate fermentation experiments confirmed that this substrate supported the growth of L.crispatus Lc31 and Lc83.Our findings improve the understanding of how the genome determines niche adaptation by L.crispatus,providing a foundation for investigating the mechanisms by which urogenital-derived L.crispatus promotes female health.
文摘The development of an active, durable, and metal-free carbocatalyst that is able to replace metal-based catalysts is of increasing scientific and technological importance. The use of such a catalyst would avoid problems caused by metal- containing catalysts, for example, environmental pollution by heavy metals and depletion of rare metal resources. Herein, an active and durable graphene carbocatalyst is presented for the carbocatalytic conversion of 4-nitrophenol to 4-aminophenol at ambient temperature. The carbocatalyst was prepared via a mild, water-based reaction between L-ascorbic acid （AA） and graphene oxide （GO） and did not involve any other reactants. During the structure and catalytic property optimization, a series of carbocatalysts were fabricated at various reaction temperatures and AA/GO ratios. Using several characterization techniques, detailed structural features of these carbocatalysts were identified. Possible active species and sites on the carbocatalysts were also identified such as certain oxygen-containing groups, the ~x-conjugated system, and graphene sheet edges. In addition, the synergistic effect between these active species and sites on the resulting catalytic activity is highlighted. Furthermore, we clarified the origin of the high stability and durability of the optimized carbocatalyst. The work presented here aids the design of high-performance carbocatalysts for hydrogenation reactions, and increases understanding of the structural and mechanistic aspects at the molecular level that lead to high catalyst activity and durability.
