Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caus...Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caused by a variety of reasons,including ions diffusion,surface and grain boundary defects,etc.In this work,the cross-linkable tannic acid(TA)is introduced to modify perovskite film through post-treatment method.The numerous organic functional groups(–OH and C=O)in TA can interact with the uncoordinated Pb^(2+)and I^(-)ions in perovskite,thus passivating defects and inhibiting ions diffusion.In addition,the formed TA network can absorb a small amount of the residual moisture inside the device to protect the perovskite layer.Furthermore,TA modification regulates the energy level of perovskite,and reduces interfacial charge recombination.Ultimately,following TA treatment,the device efficiency is increased significantly from 21.31%to 23.11%,with a decreased hysteresis effect.Notably,the treated device shows excellent air,thermal,and operational stability.In light of this,the readily available,inexpensive TA has the potential to operate as a multipurpose interfacial modifier to increase device efficiency while also enhancing device stability.展开更多
The poor thermal stability and high sensitivity severely hinder the practical application of hexanitrohexaazaisowurtzitane(CL-20).Herein,a kind of novel core@double-shell CL-20 based energetic composites were fabricat...The poor thermal stability and high sensitivity severely hinder the practical application of hexanitrohexaazaisowurtzitane(CL-20).Herein,a kind of novel core@double-shell CL-20 based energetic composites were fabricated to address the above issues.The coordination complexes which consist of natural polyphenol tannic acid(TA) and Fe~Ⅲ were chosen to construct the inner shell,while the graphene sheets were used to build the outer shell.The resulting CL-20/TA-Fe~Ⅲ/graphene composites exhibited simultaneously improved thermal stability and safety performance with only 1 wt% double-shell content,which should be ascribed to the intense physical encapsulation effect from inner shell combined with the desensitization effect of carbon nano-materials from outer shell.The phase transition(ε to γ) temperature increased from 173.70 ℃ of pure CL-20 to 191.87℃ of CL-20/TA-Fe~Ⅲ/graphene composites.Meanwhile,the characteristic drop height(H_(50)) dramatically increased from 14.7 cm of pure CL-20 to112.8 cm of CL-20/TA-Fe~Ⅲ/graphene composites,indicating much superior safety performance after the construction of the double-shell structure.In general,this work has provided an effective and versatile strategy to conquer the thermal stability and safety issues of CL-20 and contributes to the future application of high energy density energetic materials.展开更多
The variation of the principal stress of formations with the working and geo-mechanical conditions can trigger wellbore instabilities and adversely affect the well completion.A finite element model,based on the theory...The variation of the principal stress of formations with the working and geo-mechanical conditions can trigger wellbore instabilities and adversely affect the well completion.A finite element model,based on the theory of poro-elasticity and the Mohr-Coulomb rock damage criterion,is used here to analyze such a risk.The changes in wellbore stability before and after reservoir acidification are simulated for different pressure differences.The results indicate that the risk of wellbore instability grows with an increase in the production-pressure difference regardless of whether acidification is completed or not;the same is true for the instability area.After acidizing,the changes in the main geomechanical parameters(i.e.,elastic modulus,Poisson’s ratio,and rock strength)cause the maximum wellbore instability coefficient to increase.展开更多
The general objective of the work is to compare the effect of the addition of synthetic citric acid compared to the addition of natural fruit juice of Citrus aurantiifolia on the conservation of drink based on red cha...The general objective of the work is to compare the effect of the addition of synthetic citric acid compared to the addition of natural fruit juice of Citrus aurantiifolia on the conservation of drink based on red chalice H. sabdariffa. The tests were carried out over a period of 5 weeks at 4°C and 37°C with seven batches of beverage samples prepared at the rate of a calyx/water ratio of 1/40 (kg·kg<sup>-1</sup>) and added respectively citric acid at 1, 2 and 4 g·L<sup>-1</sup> and lemon juice at 10, 20 and 40 mL·L<sup>-1</sup>. The characterization of the different batches of beverages was carried out from day one. A follow-up of the residual anthocyanin content and the intensity of the red coloring were carried out over five weeks. The anthocyanin concentration was determined by the pH-differential method. The red color degradation index is determined based on the CIELAB color system (L*, a*, b* and L*). R and Minitab 18 software was used for data processing. The results of the monitoring of the parameters showed that the concentration of 1 g AC L<sup>-1</sup> retains 2.7 mg more of the anthocyanins than adding 10 mL JC L<sup>-1</sup> and longer maintains red color when stored at 4°C and 37°C/5 weeks. The 2 g AC L<sup>-1</sup> and 4 g AC L<sup>-1</sup> ratios have the same effects as the addition of 20 and 40 mL of lemon juice, all accelerating the degradation of anthocyanins and the red color. After 5 weeks of storage at 37°C, the effect of the temperature combined with the increase in the acidity of the samples (2 to 4 g AC L<sup>-1</sup> and 20 to 40 ml JC L<sup>-1</sup>), have accelerated the total disappearance of the red color on all samples.展开更多
This study was conducted to evaluate the effect of lactic acid bacteria and propionic acid on the fermentation quality, aer- obic stability and in vitro gas production kinetics and digestibility of whole-crop corn bas...This study was conducted to evaluate the effect of lactic acid bacteria and propionic acid on the fermentation quality, aer- obic stability and in vitro gas production kinetics and digestibility of whole-crop corn based totalmixed ration (TMR) silage. Total mixed ration was ensiled with four treatments: (1) no additives (control); (2) an inoculant (Lactobacillus plantarum) (L); (3) propionicacid (P); (4) propionic acid+lactic acid bacteria (PL). All treatments were ensiled in laboratory-scale silos for 45 days, and then subjected to an aerobic stability test for12 days. Further, four TMR silages were incubated in vitro with buffered rumen fluid to study in vitro gas production kinetics and digestibility. The results indicated that all TMR silages had good fermentation characteristics with low pH (〈3.80) and ammonia nitrogen (NH3-N) contents, and high lactic acid contents as well as Flieg points. Addition of L further improved TMR silage quality with more lactic acid production. Addition of P and PL decreased lactic acid and NH3-N contents of TMR silage compared to the control (P〈0.05). After 12 days aerobic exposure, P and PL silages remained stable, but L and the control silages deteriorated as indicated by a reduction in lactic acid and an increase in pH, and numbers of yeast. Compared to the control, addition of L had no effects on TMR silage in terms of 72 h cumulative gas production, in vitro dry matter digestibility, metabolizable energy, net energy for lactation and short chain fatty acids, whereas addition of PL significantly (P〈0.05) increased them. L silage had higher (P〈0.05) in vitro neutral detergent fiber digestibility than the control silage. The results of our study suggested that TMR silage prepared with whole-crop corn can be well preserved with or without additives. Furthermore, the findings of this study suggested that propionic acid is compatible with lactic acid bacteria inoculants, and when used together, although they reduced lactic acid production of TMR silage, they improved aerobic stability and in vitro nutrients digestibility of TMR silage.展开更多
Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inh...Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on c AMP-phosphodiesterase(PDE). To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate c AMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund's adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4 A expression(P〈0.01), and had no influence on the expressions of PDE4 B and 4D. However, PDE4 C expression was not detected. Gallic acid could promote IL-6 release(P〈0.05), and inhibit TNF-α release of neutrophils(P〈0.05). The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model(P〈0.05). Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.展开更多
The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode.Two electrons and two protons participa...The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode.Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10^(-5) cm^2/s.The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated.This work provided a simple approach to selectively and sensitively de...展开更多
Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina bengh...Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa and Ziziphus mauritiana, as well as their constituents(gallic acid, emodin, and isovanillic acid). Methods: All the samples were tested for cytotoxicity on baby hamster kidney cells by MTT assay and for anti-DENV-2 activity by plaque reduction neutralization assay using two DENV-2 doses(45 and 90 plaqueforming units or PFU). Results: All the samples except isovanillic acid exhibited significant prophylactic effects against DENV-2 infectivity(without cytotoxicity) when administered to cells before infection, but were not effective when given 6 h post-infection. The methanol extract of Rumex dentatus demonstrated the highest antiviral efficacy by inhibiting DENV-2 replication, with IC_(50) of 0.154 μg/mL and 0.234 μg/mL, when added before infection with 45 and 90 PFU of virus, respectively. Gallic acid also exhibited significant antiviral effects by prophylactic treatment prior to virus adsorption on cells, with IC_(50) of 0.191 μg/mL and 0.522 μg/mL at 45 and 90 PFU of DENV-2 infection, respectively. Conclusions: The highly potent activities of the extracts and constituent compounds of these plants against DENV-2 infectivity highlight their potential as targets for further research to identify novel antiviral agents against dengue.展开更多
The binding of drugs with human serum albumin(HSA) is a crucial factor influencing the distribution and bioactivity of drugs in the body.To understand the action mechanisms between gallic acid(GA,3,4,5-trihydroxybe...The binding of drugs with human serum albumin(HSA) is a crucial factor influencing the distribution and bioactivity of drugs in the body.To understand the action mechanisms between gallic acid(GA,3,4,5-trihydroxybenzoic acid) and HSA,the binding of GA with HSA was investigated by a combined experimental and computational approach.The fluorescence properties of HSA and the binding parameters of GA collectively indicate that the binding is characterized by static quenching mechanism at one high affinity binding site.According to the estimated molecular distance between the donor(HSA) and the acceptor(GA),the binding is related to the fluorescence resonance energy transfer.As indicated by the thermodynamic parameters,hydrophobic interaction plays a major role in the GA-HSA complex.Further,the experimental results reveal that GA is bound in the large hydrophobic cavity of subdomain IIA in the site I of HSA,which is well approved by molecular docking.展开更多
A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were character...A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75. The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermal stability and excellent solubility.展开更多
A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic...A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic, space group Co, a = 14.0133(14), b = 16.0409(16), c = 30.372(3) A, β = 100.8950(10)°, V = 6704.1(12) A3, Dc = 1.364 g/cm3, Z = 8,μ(MoKa) = 0.704 mml, F(000) = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.展开更多
To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structure...To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structures of the compound GA-CS copolymer were characterized,fully indicating that gallic acid is resoundingly grafted onto chitosan.The grafting ratios of three copolymers GA-CS are 45.71%(Ⅰ),36.12%(Ⅱ),and 18.96%(Ⅲ)were determined by UV-Vis spectrophotometer.The minimum inhibitory concentrations of three GA-CS copolymers are 30μg/mL against Escherichia coli and are ranged from 250 to 550μg/mL against Staphylococcus aureus.By counting viable bacterial colonies,it can be found that antibacterial property is preferable by increasing the grafting ratio of GA-CS copolymers.Findings of investigation on aforementioned bacteria experiment indicate that the CFU/mL values of GA-CS(Ⅰ,Ⅱ,Ⅲ)are 2.04×10^(6),7.56×10^(6),1.48×10^(7) to Staphylococcus aureus,and 2.96×10^(6),1.01×10^(7),2.14×10^(7) to Escherichia coli after 12 h treatment.In addition,the interaction process between GA-CS copolymer and bacteria can be observed through a transmission electron microscope.The specific manifestation is that the bacterial cell membranes are ruptured after being treated with the copolymer,which causes the cell contents to flow out,and the cell morphology is shrunk and out ofshape.展开更多
A novel Cd(Ⅱ) coordination polymer, [CdCI(Hpc)H2O]n (1, H2pc = 1H-pyrazole-3- carboxylic acid), was synthesized by the reaction of CdCl2·2.5H2O with H2pc, and structurally characterized by IR spectrum, UV-...A novel Cd(Ⅱ) coordination polymer, [CdCI(Hpc)H2O]n (1, H2pc = 1H-pyrazole-3- carboxylic acid), was synthesized by the reaction of CdCl2·2.5H2O with H2pc, and structurally characterized by IR spectrum, UV-Vis spectrum, elemental analysis, single-crystal X-ray diffraction, as well as thermal analysis. Compound 1 crystallizes in monoclinic, P21/n space group with α = 7.0304(3), b = 10.3047(3), c = 10.6446(4) A, β= 107.174(4)°, F = 736.78(5) A^3, Z = 4, C4HsCdClN2O3, Mr = 276.95, Dc = 2.497 g/cm%3, F(000) = 528.0,μ= 3.281 mm^-1, R = 0.0169 and wR = 0.0387. The central metals adopt distorted octahedral geometry. Carboxyl groups of the ligand connect Cd(Ⅱ) into a one-dimensional chain, which further constructs a two-dimensional network by halogen bridging. Such two-dimensional structures are finally connected into a three-dimensional supramolecular architecture due to the hydrogen bonds and intermolecular π…π interactions. In addition, complex 1 has high thermal stability.展开更多
The influence of mica particles on the rheological and thermal properties of poly( lactic acid)( PLA) / mica composites were investigated by capillary rheometer and thermogravimetric( TG)analysis. The results show tha...The influence of mica particles on the rheological and thermal properties of poly( lactic acid)( PLA) / mica composites were investigated by capillary rheometer and thermogravimetric( TG)analysis. The results show that the PLA / mica blends are nonNewtonian pseudoplastic and display shear-thinning. The value of non-Newtonian index of the blends melt decreased obviously with the addition of mica particles but somehow even increased when shear rate exceeded 4 500 s- 1. In this work,it could be indicated that appropriate amount of mica particles could somehow enhance the resistance of PLA melt under high shear rate to deviate from Newtonian fluid. TG analysis shows that the thermal stability of PLA decreases a little after the incorporation of the mica particles.As mica particles decompose in a completely different way in contrast to PLA,this abnormal decrease of thermal stability of PLA / mica composite may be attributed to moisture stored between mica layers released at high temperature.展开更多
Alpha-lipoic acid-loaded lipid nanoparticles(ALA-LNs) were prepared by high pressure homogenization method.The influences of storage conditions such as time and temperature on the physical and chemical storage stabili...Alpha-lipoic acid-loaded lipid nanoparticles(ALA-LNs) were prepared by high pressure homogenization method.The influences of storage conditions such as time and temperature on the physical and chemical storage stability of ALA-LNs were studied in details.The stability was evaluated by particle size and polydispersity index,morphology of ALA-LNs,and capacity of ALA loading.The dilution and pH stability of ALA-LNs suspensions were also studied.After three months storage,the mean size of ALA-LNs at 4 and 40 ℃ was increased by 2.68% and 3.62% compared with the original size,respectively.ALA-LNs stored at 40 ℃ had ellipsoid shape and the mean size was about 152 nm(SD=23.6).The loading capacity of ALA at 40 ℃ was much higher than those stored at other two temperatures.The good dilution and pH stability were also demonstrated.The sample had good fluidity even at 4 ℃.展开更多
Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,w...Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,we prepared mixed gels with antiultraviolet properties.This study found that the addition of polysaccharides and polyphenols was beneficial to the rheological,me-chanical properties,and biological activity of the protein.Chitosan(CS)could significantly improve the viscoelasticity,hardness,gel strength,thermal stability and crystallinity of gelatin.Interestingly,the addition of gallic acid(GA)could not only provide significant cross-linking effect,improve gel properties and microstructure,but also improve the UV resistance of the mixed gel.展开更多
Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are op...Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are optically unstable in the process of self chemical ionization.展开更多
Objective:To evaluate the effect of free and liposome form of gallic acid on bone regeneration in critical defects in Wistar rats.Methods:Thirty-two female Wistar rats were divided into four study groups:group 1,negat...Objective:To evaluate the effect of free and liposome form of gallic acid on bone regeneration in critical defects in Wistar rats.Methods:Thirty-two female Wistar rats were divided into four study groups:group 1,negative control;group 2,positive control;group 3,gallic acid powder;group 4,gallic acid liposome.A critical-sized defect was created in all rats.Groups 2 to 4 had xenograft,autograft and membrane placement while negative control rats did not receive any treatment.The defect area was sutured and rats were kept alive for 30 d.At the end of the study,a bone specimen including the defect area was removed from calvaria.All specimens were evaluated under the stereomicroscope,then underwent histological analysis.Inflammatory cell counts,osteoblast,osteoclast counts,receptor activator of nuclear factorκ-B(RANKL),osteoprotegerin(OPG),runt-related transcription factor 2(Runx2),bone morphogenetic protein-2(BMP-2),and alkaline phosphatase were determined.Results:The biggest unhealed defect area was observed in the negative control group and the smallest was observed in the gallic acid liposome group.There were no differences between the positive control group vs.the gallic acid powder group and the gallic acid powder group vs.the gallic acid liposome group.The severity of inflammation was the highest in the negative control group and the lowest in the gallic acid liposome group with significant differences between the groups.All groups had similar osteoblast counts while osteoclast counts were the highest in the positive control group.Gallic acid groups had a lower number of osteoclasts compared with the positive control group.Runx2 and alkaline phosphatase levels were similar in the groups while OPG and BMP-2 levels exhibited a significant increase compared with the negative control group and the positive control group.RANKL was similar in the negative control group,the positive control group,and the gallic acid powder groups but decreased in the gallic acid liposome group.Conclusions:Gallic acid powder and liposome significantly improve bone regeneration in Wistar rats with calvarial defects.The improvement in healing is evident with decreased inflammation and RANKL expressions and increased OPG and BMP-2 expressions.展开更多
[Objective]The paper was to determine the contents of gallic acid and cinnamic acid in Chinese herb rhubarb by HPLC.[Method]High performance liquid chromatography(HPLC)was established with the following conditions:The...[Objective]The paper was to determine the contents of gallic acid and cinnamic acid in Chinese herb rhubarb by HPLC.[Method]High performance liquid chromatography(HPLC)was established with the following conditions:Thermo SCIENTIFIC Hypersil GOLD Dim column(4.6 mm×250 mm,5μm),mobile phase methanol-0.1%phosphoric acid solution,gradient elution,detection wavelength 278 nm,flow rate 1.0 mL/min,column temperature 30℃,injection volume 10 pL.[Result]The content of gallic acid and cinnamic acid in rhubarb was determined by HPLC,and they showed good linear relationship in the linear ranges of 0.125-1.250 pg(E2=0.9998)and 0.0382-0.3820μg(E2=0.9994),respectively.[Conclusion]A HPLC method is established to determine gallic acid and cinnamic acid content in rhubarb.The method will provide a scientific basis for quality control of rhubarb and its traditional Chinese medicine.展开更多
To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secon...To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secondary structure is still unclear. Here we perform molecular simulations on a series of helical structures. Our data show that the dissociation energy of the helical structure is related to the preference of amino acids, and the electrostatic repulsion of the residue i and i + 3/4 with the same sign of charge destabilizes the alpha helix.展开更多
基金supported by the General Program of Chongqing Natural Science Foundation(CSTB2022NSCQMSX1227 and CSTB2022NSCQ-MSX0459)the supports from the Fundamental Research Funds for the Central Universities(SWU-XDJH202314)。
文摘Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caused by a variety of reasons,including ions diffusion,surface and grain boundary defects,etc.In this work,the cross-linkable tannic acid(TA)is introduced to modify perovskite film through post-treatment method.The numerous organic functional groups(–OH and C=O)in TA can interact with the uncoordinated Pb^(2+)and I^(-)ions in perovskite,thus passivating defects and inhibiting ions diffusion.In addition,the formed TA network can absorb a small amount of the residual moisture inside the device to protect the perovskite layer.Furthermore,TA modification regulates the energy level of perovskite,and reduces interfacial charge recombination.Ultimately,following TA treatment,the device efficiency is increased significantly from 21.31%to 23.11%,with a decreased hysteresis effect.Notably,the treated device shows excellent air,thermal,and operational stability.In light of this,the readily available,inexpensive TA has the potential to operate as a multipurpose interfacial modifier to increase device efficiency while also enhancing device stability.
基金financially supported by the National Natural Science Foundation of China (Grant No. 22275173)the Open Project of State Key Laboratory of Environment-friendly Energy Materials (Grant No. 22kfhg10)。
文摘The poor thermal stability and high sensitivity severely hinder the practical application of hexanitrohexaazaisowurtzitane(CL-20).Herein,a kind of novel core@double-shell CL-20 based energetic composites were fabricated to address the above issues.The coordination complexes which consist of natural polyphenol tannic acid(TA) and Fe~Ⅲ were chosen to construct the inner shell,while the graphene sheets were used to build the outer shell.The resulting CL-20/TA-Fe~Ⅲ/graphene composites exhibited simultaneously improved thermal stability and safety performance with only 1 wt% double-shell content,which should be ascribed to the intense physical encapsulation effect from inner shell combined with the desensitization effect of carbon nano-materials from outer shell.The phase transition(ε to γ) temperature increased from 173.70 ℃ of pure CL-20 to 191.87℃ of CL-20/TA-Fe~Ⅲ/graphene composites.Meanwhile,the characteristic drop height(H_(50)) dramatically increased from 14.7 cm of pure CL-20 to112.8 cm of CL-20/TA-Fe~Ⅲ/graphene composites,indicating much superior safety performance after the construction of the double-shell structure.In general,this work has provided an effective and versatile strategy to conquer the thermal stability and safety issues of CL-20 and contributes to the future application of high energy density energetic materials.
基金This work is financially sponsored by Tarim Oilfield“Study on Adaptability Evaluation and Parameter Optimization of Completion Technology in Bozi Block,Tarim Oilfield”(Item Number:201021113436).
文摘The variation of the principal stress of formations with the working and geo-mechanical conditions can trigger wellbore instabilities and adversely affect the well completion.A finite element model,based on the theory of poro-elasticity and the Mohr-Coulomb rock damage criterion,is used here to analyze such a risk.The changes in wellbore stability before and after reservoir acidification are simulated for different pressure differences.The results indicate that the risk of wellbore instability grows with an increase in the production-pressure difference regardless of whether acidification is completed or not;the same is true for the instability area.After acidizing,the changes in the main geomechanical parameters(i.e.,elastic modulus,Poisson’s ratio,and rock strength)cause the maximum wellbore instability coefficient to increase.
文摘The general objective of the work is to compare the effect of the addition of synthetic citric acid compared to the addition of natural fruit juice of Citrus aurantiifolia on the conservation of drink based on red chalice H. sabdariffa. The tests were carried out over a period of 5 weeks at 4°C and 37°C with seven batches of beverage samples prepared at the rate of a calyx/water ratio of 1/40 (kg·kg<sup>-1</sup>) and added respectively citric acid at 1, 2 and 4 g·L<sup>-1</sup> and lemon juice at 10, 20 and 40 mL·L<sup>-1</sup>. The characterization of the different batches of beverages was carried out from day one. A follow-up of the residual anthocyanin content and the intensity of the red coloring were carried out over five weeks. The anthocyanin concentration was determined by the pH-differential method. The red color degradation index is determined based on the CIELAB color system (L*, a*, b* and L*). R and Minitab 18 software was used for data processing. The results of the monitoring of the parameters showed that the concentration of 1 g AC L<sup>-1</sup> retains 2.7 mg more of the anthocyanins than adding 10 mL JC L<sup>-1</sup> and longer maintains red color when stored at 4°C and 37°C/5 weeks. The 2 g AC L<sup>-1</sup> and 4 g AC L<sup>-1</sup> ratios have the same effects as the addition of 20 and 40 mL of lemon juice, all accelerating the degradation of anthocyanins and the red color. After 5 weeks of storage at 37°C, the effect of the temperature combined with the increase in the acidity of the samples (2 to 4 g AC L<sup>-1</sup> and 20 to 40 ml JC L<sup>-1</sup>), have accelerated the total disappearance of the red color on all samples.
基金supported by the project of Jiangsu Independent Innovation,China(CX(15)1003-3)the Key Technologies R&D Program of China during the 13th Five-Year Plan period(2016YFC0502005)the Special Project of Grass of Tibet Autonomous Region for the 13th Five-Year Plan,China
文摘This study was conducted to evaluate the effect of lactic acid bacteria and propionic acid on the fermentation quality, aer- obic stability and in vitro gas production kinetics and digestibility of whole-crop corn based totalmixed ration (TMR) silage. Total mixed ration was ensiled with four treatments: (1) no additives (control); (2) an inoculant (Lactobacillus plantarum) (L); (3) propionicacid (P); (4) propionic acid+lactic acid bacteria (PL). All treatments were ensiled in laboratory-scale silos for 45 days, and then subjected to an aerobic stability test for12 days. Further, four TMR silages were incubated in vitro with buffered rumen fluid to study in vitro gas production kinetics and digestibility. The results indicated that all TMR silages had good fermentation characteristics with low pH (〈3.80) and ammonia nitrogen (NH3-N) contents, and high lactic acid contents as well as Flieg points. Addition of L further improved TMR silage quality with more lactic acid production. Addition of P and PL decreased lactic acid and NH3-N contents of TMR silage compared to the control (P〈0.05). After 12 days aerobic exposure, P and PL silages remained stable, but L and the control silages deteriorated as indicated by a reduction in lactic acid and an increase in pH, and numbers of yeast. Compared to the control, addition of L had no effects on TMR silage in terms of 72 h cumulative gas production, in vitro dry matter digestibility, metabolizable energy, net energy for lactation and short chain fatty acids, whereas addition of PL significantly (P〈0.05) increased them. L silage had higher (P〈0.05) in vitro neutral detergent fiber digestibility than the control silage. The results of our study suggested that TMR silage prepared with whole-crop corn can be well preserved with or without additives. Furthermore, the findings of this study suggested that propionic acid is compatible with lactic acid bacteria inoculants, and when used together, although they reduced lactic acid production of TMR silage, they improved aerobic stability and in vitro nutrients digestibility of TMR silage.
基金financial support of the Beijing Natural Science Foundation of China (6112007)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality,China (PHR201107134)2012 Scientific Research Quality Raising Funds of Beijing University of Agriculture,China (PXM2012_014207_000010/ PXM2012_014207_000013)
文摘Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on c AMP-phosphodiesterase(PDE). To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate c AMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund's adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4 A expression(P〈0.01), and had no influence on the expressions of PDE4 B and 4D. However, PDE4 C expression was not detected. Gallic acid could promote IL-6 release(P〈0.05), and inhibit TNF-α release of neutrophils(P〈0.05). The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model(P〈0.05). Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.
文摘The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode.Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10^(-5) cm^2/s.The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated.This work provided a simple approach to selectively and sensitively de...
基金support of the National University of SingaporeQuaid-i-Azam University
文摘Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa and Ziziphus mauritiana, as well as their constituents(gallic acid, emodin, and isovanillic acid). Methods: All the samples were tested for cytotoxicity on baby hamster kidney cells by MTT assay and for anti-DENV-2 activity by plaque reduction neutralization assay using two DENV-2 doses(45 and 90 plaqueforming units or PFU). Results: All the samples except isovanillic acid exhibited significant prophylactic effects against DENV-2 infectivity(without cytotoxicity) when administered to cells before infection, but were not effective when given 6 h post-infection. The methanol extract of Rumex dentatus demonstrated the highest antiviral efficacy by inhibiting DENV-2 replication, with IC_(50) of 0.154 μg/mL and 0.234 μg/mL, when added before infection with 45 and 90 PFU of virus, respectively. Gallic acid also exhibited significant antiviral effects by prophylactic treatment prior to virus adsorption on cells, with IC_(50) of 0.191 μg/mL and 0.522 μg/mL at 45 and 90 PFU of DENV-2 infection, respectively. Conclusions: The highly potent activities of the extracts and constituent compounds of these plants against DENV-2 infectivity highlight their potential as targets for further research to identify novel antiviral agents against dengue.
基金Supported by the Project of Department of Science and Technology of Jilin Province,China(No.20070424)
文摘The binding of drugs with human serum albumin(HSA) is a crucial factor influencing the distribution and bioactivity of drugs in the body.To understand the action mechanisms between gallic acid(GA,3,4,5-trihydroxybenzoic acid) and HSA,the binding of GA with HSA was investigated by a combined experimental and computational approach.The fluorescence properties of HSA and the binding parameters of GA collectively indicate that the binding is characterized by static quenching mechanism at one high affinity binding site.According to the estimated molecular distance between the donor(HSA) and the acceptor(GA),the binding is related to the fluorescence resonance energy transfer.As indicated by the thermodynamic parameters,hydrophobic interaction plays a major role in the GA-HSA complex.Further,the experimental results reveal that GA is bound in the large hydrophobic cavity of subdomain IIA in the site I of HSA,which is well approved by molecular docking.
文摘A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75. The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermal stability and excellent solubility.
基金Supported by the Natural Science Foundation of Hunan Province (No. 11JJ9006)Key Project of Science and Technology Plan of Hunan Province (2012FJ2002)+1 种基金Science and Technology Plan of Hunan Province (2012GK3031, 2012WK3029)the Construct Program of Key Discipline in Hunan Province
文摘A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic, space group Co, a = 14.0133(14), b = 16.0409(16), c = 30.372(3) A, β = 100.8950(10)°, V = 6704.1(12) A3, Dc = 1.364 g/cm3, Z = 8,μ(MoKa) = 0.704 mml, F(000) = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.
基金Funded by the Health Commission of Hubei Province Scientific Research Project(No.WJ2019H275)。
文摘To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structures of the compound GA-CS copolymer were characterized,fully indicating that gallic acid is resoundingly grafted onto chitosan.The grafting ratios of three copolymers GA-CS are 45.71%(Ⅰ),36.12%(Ⅱ),and 18.96%(Ⅲ)were determined by UV-Vis spectrophotometer.The minimum inhibitory concentrations of three GA-CS copolymers are 30μg/mL against Escherichia coli and are ranged from 250 to 550μg/mL against Staphylococcus aureus.By counting viable bacterial colonies,it can be found that antibacterial property is preferable by increasing the grafting ratio of GA-CS copolymers.Findings of investigation on aforementioned bacteria experiment indicate that the CFU/mL values of GA-CS(Ⅰ,Ⅱ,Ⅲ)are 2.04×10^(6),7.56×10^(6),1.48×10^(7) to Staphylococcus aureus,and 2.96×10^(6),1.01×10^(7),2.14×10^(7) to Escherichia coli after 12 h treatment.In addition,the interaction process between GA-CS copolymer and bacteria can be observed through a transmission electron microscope.The specific manifestation is that the bacterial cell membranes are ruptured after being treated with the copolymer,which causes the cell contents to flow out,and the cell morphology is shrunk and out ofshape.
基金supported by the National Natural Science Foundation of China(No.20801012)New Energy Technology Co.Ltd.of Ai Naji of Jiangsu Province(No.8507040091)
文摘A novel Cd(Ⅱ) coordination polymer, [CdCI(Hpc)H2O]n (1, H2pc = 1H-pyrazole-3- carboxylic acid), was synthesized by the reaction of CdCl2·2.5H2O with H2pc, and structurally characterized by IR spectrum, UV-Vis spectrum, elemental analysis, single-crystal X-ray diffraction, as well as thermal analysis. Compound 1 crystallizes in monoclinic, P21/n space group with α = 7.0304(3), b = 10.3047(3), c = 10.6446(4) A, β= 107.174(4)°, F = 736.78(5) A^3, Z = 4, C4HsCdClN2O3, Mr = 276.95, Dc = 2.497 g/cm%3, F(000) = 528.0,μ= 3.281 mm^-1, R = 0.0169 and wR = 0.0387. The central metals adopt distorted octahedral geometry. Carboxyl groups of the ligand connect Cd(Ⅱ) into a one-dimensional chain, which further constructs a two-dimensional network by halogen bridging. Such two-dimensional structures are finally connected into a three-dimensional supramolecular architecture due to the hydrogen bonds and intermolecular π…π interactions. In addition, complex 1 has high thermal stability.
文摘The influence of mica particles on the rheological and thermal properties of poly( lactic acid)( PLA) / mica composites were investigated by capillary rheometer and thermogravimetric( TG)analysis. The results show that the PLA / mica blends are nonNewtonian pseudoplastic and display shear-thinning. The value of non-Newtonian index of the blends melt decreased obviously with the addition of mica particles but somehow even increased when shear rate exceeded 4 500 s- 1. In this work,it could be indicated that appropriate amount of mica particles could somehow enhance the resistance of PLA melt under high shear rate to deviate from Newtonian fluid. TG analysis shows that the thermal stability of PLA decreases a little after the incorporation of the mica particles.As mica particles decompose in a completely different way in contrast to PLA,this abnormal decrease of thermal stability of PLA / mica composite may be attributed to moisture stored between mica layers released at high temperature.
基金Supported by International Scientific Cooperation Project of China (No.2008DFB50060)Suzhou Innovation Funds of High-Tech Enterprise (No.SG0958)
文摘Alpha-lipoic acid-loaded lipid nanoparticles(ALA-LNs) were prepared by high pressure homogenization method.The influences of storage conditions such as time and temperature on the physical and chemical storage stability of ALA-LNs were studied in details.The stability was evaluated by particle size and polydispersity index,morphology of ALA-LNs,and capacity of ALA loading.The dilution and pH stability of ALA-LNs suspensions were also studied.After three months storage,the mean size of ALA-LNs at 4 and 40 ℃ was increased by 2.68% and 3.62% compared with the original size,respectively.ALA-LNs stored at 40 ℃ had ellipsoid shape and the mean size was about 152 nm(SD=23.6).The loading capacity of ALA at 40 ℃ was much higher than those stored at other two temperatures.The good dilution and pH stability were also demonstrated.The sample had good fluidity even at 4 ℃.
基金supported by the National Natural Sci-ence Foundation of China(No.31922072)the China Agri-culture Research System(No.CARS-48)+1 种基金the Fundamen-tal Research Funds for the Central Universities(No.201941002)the Taishan Scholar Project of Shandong Province(No.tsqn201812020).
文摘Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,we prepared mixed gels with antiultraviolet properties.This study found that the addition of polysaccharides and polyphenols was beneficial to the rheological,me-chanical properties,and biological activity of the protein.Chitosan(CS)could significantly improve the viscoelasticity,hardness,gel strength,thermal stability and crystallinity of gelatin.Interestingly,the addition of gallic acid(GA)could not only provide significant cross-linking effect,improve gel properties and microstructure,but also improve the UV resistance of the mixed gel.
文摘Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are optically unstable in the process of self chemical ionization.
文摘Objective:To evaluate the effect of free and liposome form of gallic acid on bone regeneration in critical defects in Wistar rats.Methods:Thirty-two female Wistar rats were divided into four study groups:group 1,negative control;group 2,positive control;group 3,gallic acid powder;group 4,gallic acid liposome.A critical-sized defect was created in all rats.Groups 2 to 4 had xenograft,autograft and membrane placement while negative control rats did not receive any treatment.The defect area was sutured and rats were kept alive for 30 d.At the end of the study,a bone specimen including the defect area was removed from calvaria.All specimens were evaluated under the stereomicroscope,then underwent histological analysis.Inflammatory cell counts,osteoblast,osteoclast counts,receptor activator of nuclear factorκ-B(RANKL),osteoprotegerin(OPG),runt-related transcription factor 2(Runx2),bone morphogenetic protein-2(BMP-2),and alkaline phosphatase were determined.Results:The biggest unhealed defect area was observed in the negative control group and the smallest was observed in the gallic acid liposome group.There were no differences between the positive control group vs.the gallic acid powder group and the gallic acid powder group vs.the gallic acid liposome group.The severity of inflammation was the highest in the negative control group and the lowest in the gallic acid liposome group with significant differences between the groups.All groups had similar osteoblast counts while osteoclast counts were the highest in the positive control group.Gallic acid groups had a lower number of osteoclasts compared with the positive control group.Runx2 and alkaline phosphatase levels were similar in the groups while OPG and BMP-2 levels exhibited a significant increase compared with the negative control group and the positive control group.RANKL was similar in the negative control group,the positive control group,and the gallic acid powder groups but decreased in the gallic acid liposome group.Conclusions:Gallic acid powder and liposome significantly improve bone regeneration in Wistar rats with calvarial defects.The improvement in healing is evident with decreased inflammation and RANKL expressions and increased OPG and BMP-2 expressions.
基金Supported by National Natural Science Foundation of China(81660701)2019 Guangxi First-class Discipline Construction Project of Guangxi University of Traditional Chinese Medicine(2019XK105)+3 种基金Key Laboratory Funding Project of Guangxi Zhuang and Yao Ethnic Medicine(GXZYKF2019-2,KJT19005)Natural Science Foundation of Guangxi Province(2016GXNSFAA380148)Basic Scientific Research Ability Promotion Project of Young and Middle-aged Teachers in Guangxi Universities and Colleges in 2019(2019KY0341)Level III Laboratory for Chinese Medical Research by National Administration of Traditional Chinese Medicine:Chemistry and Quality Analysis Laboratory of Zhong(Zhuang)Medicine(GZYYF 2009[21])。
文摘[Objective]The paper was to determine the contents of gallic acid and cinnamic acid in Chinese herb rhubarb by HPLC.[Method]High performance liquid chromatography(HPLC)was established with the following conditions:Thermo SCIENTIFIC Hypersil GOLD Dim column(4.6 mm×250 mm,5μm),mobile phase methanol-0.1%phosphoric acid solution,gradient elution,detection wavelength 278 nm,flow rate 1.0 mL/min,column temperature 30℃,injection volume 10 pL.[Result]The content of gallic acid and cinnamic acid in rhubarb was determined by HPLC,and they showed good linear relationship in the linear ranges of 0.125-1.250 pg(E2=0.9998)and 0.0382-0.3820μg(E2=0.9994),respectively.[Conclusion]A HPLC method is established to determine gallic acid and cinnamic acid content in rhubarb.The method will provide a scientific basis for quality control of rhubarb and its traditional Chinese medicine.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11247010,11175055,11475053 and 11347017the Natural Science Foundation for Distinguished Young Scholars of Hebei Province under Grant No C2015202340+1 种基金the Natural Science Foundation of Hebei Province under Grant Nos C2012202079 and C201400305the Scientific Innovation Fund for Excellent Young Scientists of Hebei University of Technology under Grant No 2015010
文摘To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secondary structure is still unclear. Here we perform molecular simulations on a series of helical structures. Our data show that the dissociation energy of the helical structure is related to the preference of amino acids, and the electrostatic repulsion of the residue i and i + 3/4 with the same sign of charge destabilizes the alpha helix.