Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N′-(4,4′- diphthaloyl)-bis-L-leucine (3) with six hydantoin derivatives (4a-f). Tripben...Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N′-(4,4′- diphthaloyl)-bis-L-leucine (3) with six hydantoin derivatives (4a-f). Tripbenyl phosphite (TPP)/pyridine in the presence of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The polycondensation reactions produce a series of new poly(amide-imide)s (5a-f) in high yields, and inherent viscosity between 0.42 and 0,55 dL/g. The resulting poly(amide-imide)s (5a-f) were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy.展开更多
Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in...Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (η inh ), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.展开更多
Lymphocytes respond to mitogens that stimulate proliferation by increasing theirs metabolic activity. In this study we investigate L-Glutamine and L-Leucine uptake as markers of cell response to Concavalina A (ConcaA)...Lymphocytes respond to mitogens that stimulate proliferation by increasing theirs metabolic activity. In this study we investigate L-Glutamine and L-Leucine uptake as markers of cell response to Concavalina A (ConcaA) stimulation, using a high-resolution flow technique. We found that lymphocytes induced to blast transformation enhanced rate and efficiency of amino acid uptake during cell proliferation. Considering that increases in transport is the first quantifiable response of cells during malignant transformation, amino acid uptake could also be useful as an early marker of malignancy.展开更多
Sublimed D-,L-,and DL-leucine under vacuum were subjected to ^(60)Co γ-irradiation with different doses.The enantiomeric compositions of samples were determined by chirasil- val capillary column gas chromatography,an...Sublimed D-,L-,and DL-leucine under vacuum were subjected to ^(60)Co γ-irradiation with different doses.The enantiomeric compositions of samples were determined by chirasil- val capillary column gas chromatography,and the relative yields of radiolytic products(H_2, CO_2 and NH_3)were measured by packed column gas chromatography.The obtained data showed the peak area ratios D/L of DL-leucine after different absorbed doses of irradiation are all the same as that of samples with no irradiation,within the limit of error.So are the ratios for the separately irradiated D-and L-leuicne.This suggests that no asymmetric decom- position was found.The relative yields D/L of radiolytic products(H_2,CO_2 and NH_3)are very close to 1.00,indicating that the D-leucine cleavage rate was the same with that of the L-leucine.From the view of dissipative structure,an explanation for the result was presented.展开更多
We herein report our studies into the effects of microwave irradiation on the solvent-free esterification of L-leucine with alcohols. In the absence of solvent, microwave irradiation accelerated the reaction compared ...We herein report our studies into the effects of microwave irradiation on the solvent-free esterification of L-leucine with alcohols. In the absence of solvent, microwave irradiation accelerated the reaction compared to conventional oil bath heating. Measurement of the dielectric properties under the reaction conditions revealed that the high dielectric loss factor of the reaction mixture containing L-leucine, n-butanol, and a p-toluene sulfonic acid catalyst could be attributed to the acceleration of the reaction. The depth of microwave penetration into the reaction mixture as derived from the in-situ measurement of the dielectric properties was ~13 mm, which suggested that a thinner reaction vessel was favorable for the esterification of L-leucine. In addition to the batch reaction using a desktop microwave reactor, two types of flow reaction were also performed using a desktop tubular reactor and a semi-bench-scale tubular reactor. These flow reactions also exhibited high performances, thus allowing the scale-up of this reaction system for industrial use.展开更多
Poly(ethylene oxide)(PEO)-based polymer electrolytes show the prospect in all-solid-state lithium metal batteries;however,they present limitations of low room-temperature ionic conductivity,and interfacial incompatibi...Poly(ethylene oxide)(PEO)-based polymer electrolytes show the prospect in all-solid-state lithium metal batteries;however,they present limitations of low room-temperature ionic conductivity,and interfacial incompatibility with high voltage cathodes.Therefore,a salt engineering of 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide lithium salt(LiHFDF)/LiTFSI system was developed in PEO-based electrolyte,demonstrating to effectively regulate Li ion transport and improve the interfacial stability under high voltage.We show,by manipulating the interaction between PEO matrix and TFSI^(-)-HFDF^(-),the optimized solid-state polymer electrolyte achieves maximum Li+conduction of 1.24×10^(-4)S cm^(-1)at 40℃,which is almost 3 times of the baseline.Also,the optimized polymer electrolyte demonstrates outstanding stable cycling in the LiFePO_(4)/Li and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li(3.0-4.4 V,200 cycles)based all-solid-state lithium batteries at 40℃.展开更多
With the rapid development of 5G information technology,thermal conductivity/dissipation problems of highly integrated electronic devices and electrical equipment are becoming prominent.In this work,“high-temperature...With the rapid development of 5G information technology,thermal conductivity/dissipation problems of highly integrated electronic devices and electrical equipment are becoming prominent.In this work,“high-temperature solid-phase&diazonium salt decomposition”method is carried out to prepare benzidine-functionalized boron nitride(m-BN).Subsequently,m-BN/poly(pphenylene benzobisoxazole)nanofiber(PNF)nanocomposite paper with nacremimetic layered structures is prepared via sol–gel film transformation approach.The obtained m-BN/PNF nanocomposite paper with 50 wt%m-BN presents excellent thermal conductivity,incredible electrical insulation,outstanding mechanical properties and thermal stability,due to the construction of extensive hydrogen bonds andπ–πinteractions between m-BN and PNF,and stable nacre-mimetic layered structures.Itsλ∥andλ_(⊥)are 9.68 and 0.84 W m^(-1)K^(-1),and the volume resistivity and breakdown strength are as high as 2.3×10^(15)Ωcm and 324.2 kV mm^(-1),respectively.Besides,it also presents extremely high tensile strength of 193.6 MPa and thermal decomposition temperature of 640°C,showing a broad application prospect in high-end thermal management fields such as electronic devices and electrical equipment.展开更多
Starting from(5S)-(L-menthyloxy)-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[(2S)-4-bromo-2-(L-menthyloxy)-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5(C20H32BrNO5,Mr = 446.37) was obtained in o...Starting from(5S)-(L-menthyloxy)-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[(2S)-4-bromo-2-(L-menthyloxy)-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5(C20H32BrNO5,Mr = 446.37) was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249(16),b = 19.005(3),c = 19.719(3) ,V = 4693.7(10) 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F(000) = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections(I 2σ(I)).X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N(1),C(3),C(1),C(37) and O(7) region and N(2),C(28),C(27),C(30) and O(4) region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.展开更多
Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite l...Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite layers faces challenges due to the lack of understanding of the formation mechanism and the challenge of determining the impact of self-assembled architecture on anticorrosive properties.In this study,we aimed to enhance the corrosion resistance of the MgO layer produced by plasma electrolysis(PE)of AZ31 Mg alloy by incorporating WO_(3) with partially phosphorated poly(vinyl alcohol)(PPVA).Two types of porous MgO layers were produced using the PE process with an alkaline-phosphate electrolyte,one with and one without WO_(3) nanoparticles,which were subsequently immersed in an aqueous solution of PPVA.Incorporating PPVA into the WO_(3)-MgO layer resulted in hybrids being deposited in a fragmented manner,creating a“laminar reef-like structure”that sealed most of the structural defects in the layer.The PPVA-sealed WO_(3)-based coating exhibited superior corrosion resistance compared to the other samples.Computational analyses were employed to explore the mechanism underlying the formation of PPVA/WO_(3) hybrids on the MgO layer.These findings suggest that PPVA-WO_(3)-MgO hybrid coatings can potentially improve corrosion resistance in various fields.展开更多
Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium ...Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.展开更多
The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li^(+)migr...The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li^(+)migration.Herein,we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate(LiDFOB).The Li-salt anions(DFOB−)not only accelerate the ring-opening polymerization of tetrahydrofuran,but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li^(+)conductivity of electrolytes,which is favorable for Li^(+)transport kinetics at low temperatures.Applications of this polymer electrolyte in Li||LiFePO_(4)cells show 82.3%capacity retention over 1000 cycles at 30℃and endow stable discharge capacity at−30℃.Remarkably,the Li||LiFePO4 cells retain 52%of their room-temperature capacity at−20℃and 0.1 C.This rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.展开更多
In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This st...In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This study proposes a facile fabrication process for Poly(vinylidene fluoride)(PVDF)nanofiber(NF)mats incorporating additive and nonadditive physical modifications.Patterned PVDF NF mats are prepared by electrospinning using a metal mesh as the NF collector.As a negative triboelectric material,the TENG with the patterned PVDF NF mat exhibits superior performance owing to the engineered morphology of the contact layer.PVDF is crucial in TENGs owing to its superior ferroelectric properties and surface charge density when combined with specific electroceramics.Hence,the synergy of the physical modification methods is achieved by incorporating BaTiO3(BTO)nanoparticles(NPs)into the PVDF.By functionalizing BTO NPs with polydopamine,the TENG performance is further improved owing to the enhanced dispersion of NPs and improved crystallinity of the PVDF chains.Utilizing large NPs produces a nanopatterning effect on the NF surface,thereby resulting in the hierarchical structure of the NF mats.The source of the voltage signals from the TENG is analyzed using fast Fourier transform.展开更多
The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts ...The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.展开更多
The repairing effect of poly(N-vinylpyrrolidone-co-methacrylic acid)on permed or bleached damaged hair was studied.The combing and tensile strength of permed and bleached hair before and after treatment with the copol...The repairing effect of poly(N-vinylpyrrolidone-co-methacrylic acid)on permed or bleached damaged hair was studied.The combing and tensile strength of permed and bleached hair before and after treatment with the copolymer solution were tested,and the effects of the mass fraction of copolymer solution and immerseing time on the combing and tensile strength for permed or bleached damaged hair were investigated.The repair mechanism of permed or bleached damaged hair was also explored.The results show that when the immersing time is 3 hours,the tensile strength of the permed hair increases with the mass fraction of the copolymer solution Tensile strength within 0%-0.3%,but no obvious change is observed when250 Yield strength the mass fraction is over 0.3%.Therefore,the optimal mass 200 fraction of the copolymer solution for repairing the permed hair(cN/dtex)is 0.3%.Similarly,the optimal mass fraction of the copolymer 150strength/solution for repairing the bleached hair is 0.5%.Furthermore,the effects of immersing time on the tensile strength of the100Tensile damaged hair fibers were compared between the permed and90 bleached hair before and after treatment with the copolymer500.40.30.500.10.2 solution.Coincidentally,the optimal immersion time for permedw(P(NVP-co-MAA))/%or bleached damaged hair is both 2 hours.The tensile strength of the permed and bleached hair soaked in 0.3%and 0.5%copolymer solutions for 2 hours increases by 15.55%and 18.12%,respectively,compared to untreated hair.Through infrared spectroscopy analysis,it is found that the amide II band in hair fibers shifted to the blue after repair,with the wave number shift of 11.12 and 11.09 cm^(-1),which confirm the formation of hydrogen bonds in the hair samples.Additionally,the urea hydrogen bond disruption experiment demonstrates that urea does not disrupt the hydrogen bonds in untreated hair fibers,but prevents the formation of new hydrogen bonds in damaged hair fibers.It further validates that the improvement of the tensile strength of the copolymer treated damaged hair fibers is mainly due to the formation of hydrogen bonds.After treatment with the copolymer,the dry and wet combing friction decrease by 30.73%and 28.55%for the permed hair,and decrease by 28.55%and 24.83%for the bleached hairs,respectively.The scanning electron microscope shows that the copolymer can flatten the cuticle and fill the space between the raised cuticles.展开更多
Gel-based polymer electrolytes are limited by the polarity of the residual solvent,which restricts the coupling-breaking behaviour during Li^(+)conduction,resulting in the Li^(+)transport kinetics being greatly affect...Gel-based polymer electrolytes are limited by the polarity of the residual solvent,which restricts the coupling-breaking behaviour during Li^(+)conduction,resulting in the Li^(+)transport kinetics being greatly affected.Here,we designed anion competitive gel polymer electrolyte(ACPE)by introducing lithium difluoro(oxalato)borate(LiDFOB)anion into the 1,3-dioxolane(DOL)in situ polymerisation system.ACPE enhances the ionic dipole interaction between Li^(+)and the solvent molecules and synergizes with Li^(+)across the solvation site of the polymer ethylene oxide(EO)unit,combination that greatly improves the Li^(+)transport efficiency.As a result,ACPE exhibits 1.12 mS cm^(−1)ionic conductivity and 0.75 Li^(+)transfer number at room temperature.Additionally,this intra-polymer solvation sheath allows preferential desolvation of DFOB−,which contributes to the formation of kinetically stable anion-derived interphase and effectively mitigates side reactions.Our results demonstrate that the assembled Li||NCM622 solid-state battery exhibits lifespan of over 300 cycles with average Coulombic efficiency of 98.8%and capacity retention of 80.3%.This study introduces a novel approach for ion migration and interface design,paving the way for high-safety and high-energy-density batteries.展开更多
The interfacial instability of the poly(ethylene oxide)(PEO)-based electrolytes impedes the long-term cycling and further application of all-solid-state lithium metal batter-ies.In this work,we have shown an effective...The interfacial instability of the poly(ethylene oxide)(PEO)-based electrolytes impedes the long-term cycling and further application of all-solid-state lithium metal batter-ies.In this work,we have shown an effective additive 1-adaman-tanecarbonitrile,which con-tributes to the excellent per-formance of the poly(ethylene oxide)-based electrolytes.Owing to the strong interaction of the 1-Adamantanecarboni-trile to the polymer matrix and anions,the coordination of the Li^(+)-EO is weakened,and the binding effect of anions is strengthened,thereby improving the Li^(+)conductivity and the electrochemical stability.The diamond building block on the surface of the lithium anode can sup-press the growth of lithium dendrites.Importantly,the 1-Adamantanecarbonitrile also regulates the formation of LiF in the solid electrolyte interface and cathode electrolyte interface,which contributes to the interfacial stability(especially at high voltages)and protects the electrodes,enabling all-solid-state batteries to cycle at high voltages for long periods of time.Therefore,the Li/Li symmetric cell undergoes long-term lithium plating/stripping for more than 2000 h.1-Adamantanecarbonitrile-poly(ethylene oxide)-based LFP/Li and 4.3 V Ni_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li all-solid-state batteries achieved stable cycles for 1000 times,with capacity retention rates reaching 85%and 80%,respectively.展开更多
Poly(ADP-ribose)(PAR),a polymer of ADP-ribose,is synthesized by PAR po-lymerase and is crucial for the survival of cancer cells due to its vital functions in DNA repair and post-translational modifications.Beyond its ...Poly(ADP-ribose)(PAR),a polymer of ADP-ribose,is synthesized by PAR po-lymerase and is crucial for the survival of cancer cells due to its vital functions in DNA repair and post-translational modifications.Beyond its supportive role,PAR also triggers cancer cell death by excessive accumulation of PAR leading to an energy crisis and parthanatos.This phenomenon underscores the potential of targeting PAR regulation as a novel anticancer strategy,and the rationale would present an engaging topic in the field of anticancer research.Therefore,this editorial provides an overview of the mechanisms determining cancer cell fate,emphasizing the central role of PAR.It further introduces promising methods for modulating PAR concentrations that may pave the way for innovative anticancer therapies.展开更多
Polymer solid electrolytes(SPEs)based on the[solvate-Li+]complex structure have promising prospects in lithium metal batteries(LMBs)due to their unique ion transport mechanism.However,the solvation structure may compr...Polymer solid electrolytes(SPEs)based on the[solvate-Li+]complex structure have promising prospects in lithium metal batteries(LMBs)due to their unique ion transport mechanism.However,the solvation structure may compromise the mechanical performance and safety,hindering practical application of SPEs.In this work,a composite solid electrolyte(CSE)is designed through the organic-inorganic syner-gistic interaction among N,N-dimethylformamide(DMF),polycarbonate(PC),and Mg_(2)B_(2)O_(5) in poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP).Flame-retardant Mg_(2)B_(2)O_(5) nanowires provide non-flammability to the prepared CSEs,and the addition of PC improves the dispersion of Mg_(2)B_(2)O_(5) nanowires.Simultaneously,the organic-inorganic synergistic action of PC plasticizer and Mg_(2)B_(2)O_(5) nanowires pro-motes the dissociation degree of LiTFSI and reduces the crystallinity of PVDF-HFP,enabling rapid Li ion transport.Additionally,Raman spectroscopy and DFT calculations confirm the coordination between Mg atoms in Mg_(2)B_(2)O_(5) and N atoms in DMF,which exhibits Lewis base-like behavior attacking adjacent C-F and C-H bonds in PVDF-HFP while inducing dehydrofluorination of PVDF-HFP.Based on the syner-gistic coupling of Mg_(2)B_(2)O_(5),PC,and DMF in the PVDF-HFP matrix,the prepared CSE exhibits superior ion conductivity(9.78×10^(-4) s cm^(-1)).The assembled Li symmetric cells cycle stably for 3900 h at a current density of 0.1 mA cm^(-2) without short circuit.The LFP||Li cells assembled with PDL-Mg_(2)B_(2)O_(5)/PC CSEs show excellent rate capability and cycling performance,with a capacity retention of 83.3%after 1000 cycles at 0.5 C.This work provides a novel approach for the practical application of organic-inorganic Synergistic CSEs in LMBs.展开更多
文摘Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N′-(4,4′- diphthaloyl)-bis-L-leucine (3) with six hydantoin derivatives (4a-f). Tripbenyl phosphite (TPP)/pyridine in the presence of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The polycondensation reactions produce a series of new poly(amide-imide)s (5a-f) in high yields, and inherent viscosity between 0.42 and 0,55 dL/g. The resulting poly(amide-imide)s (5a-f) were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy.
基金This project was supported by the Research Affairs Division of Arak University.
文摘Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (η inh ), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.
文摘Lymphocytes respond to mitogens that stimulate proliferation by increasing theirs metabolic activity. In this study we investigate L-Glutamine and L-Leucine uptake as markers of cell response to Concavalina A (ConcaA) stimulation, using a high-resolution flow technique. We found that lymphocytes induced to blast transformation enhanced rate and efficiency of amino acid uptake during cell proliferation. Considering that increases in transport is the first quantifiable response of cells during malignant transformation, amino acid uptake could also be useful as an early marker of malignancy.
文摘Sublimed D-,L-,and DL-leucine under vacuum were subjected to ^(60)Co γ-irradiation with different doses.The enantiomeric compositions of samples were determined by chirasil- val capillary column gas chromatography,and the relative yields of radiolytic products(H_2, CO_2 and NH_3)were measured by packed column gas chromatography.The obtained data showed the peak area ratios D/L of DL-leucine after different absorbed doses of irradiation are all the same as that of samples with no irradiation,within the limit of error.So are the ratios for the separately irradiated D-and L-leuicne.This suggests that no asymmetric decom- position was found.The relative yields D/L of radiolytic products(H_2,CO_2 and NH_3)are very close to 1.00,indicating that the D-leucine cleavage rate was the same with that of the L-leucine.From the view of dissipative structure,an explanation for the result was presented.
文摘We herein report our studies into the effects of microwave irradiation on the solvent-free esterification of L-leucine with alcohols. In the absence of solvent, microwave irradiation accelerated the reaction compared to conventional oil bath heating. Measurement of the dielectric properties under the reaction conditions revealed that the high dielectric loss factor of the reaction mixture containing L-leucine, n-butanol, and a p-toluene sulfonic acid catalyst could be attributed to the acceleration of the reaction. The depth of microwave penetration into the reaction mixture as derived from the in-situ measurement of the dielectric properties was ~13 mm, which suggested that a thinner reaction vessel was favorable for the esterification of L-leucine. In addition to the batch reaction using a desktop microwave reactor, two types of flow reaction were also performed using a desktop tubular reactor and a semi-bench-scale tubular reactor. These flow reactions also exhibited high performances, thus allowing the scale-up of this reaction system for industrial use.
基金supported by National Natural Science Foundation of China(Grant No.U1930113),ChinaNational Natural Science Foundation of China(52072036)
文摘Poly(ethylene oxide)(PEO)-based polymer electrolytes show the prospect in all-solid-state lithium metal batteries;however,they present limitations of low room-temperature ionic conductivity,and interfacial incompatibility with high voltage cathodes.Therefore,a salt engineering of 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide lithium salt(LiHFDF)/LiTFSI system was developed in PEO-based electrolyte,demonstrating to effectively regulate Li ion transport and improve the interfacial stability under high voltage.We show,by manipulating the interaction between PEO matrix and TFSI^(-)-HFDF^(-),the optimized solid-state polymer electrolyte achieves maximum Li+conduction of 1.24×10^(-4)S cm^(-1)at 40℃,which is almost 3 times of the baseline.Also,the optimized polymer electrolyte demonstrates outstanding stable cycling in the LiFePO_(4)/Li and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li(3.0-4.4 V,200 cycles)based all-solid-state lithium batteries at 40℃.
基金The authors are grateful for the support and funding from the Foundation of National Natural Science Foundation of China(52373089 and 51973173)Startup Foundation of Chongqing Normal University(23XLB011),Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202300561)Fundamental Research Funds for the Central Universities。
文摘With the rapid development of 5G information technology,thermal conductivity/dissipation problems of highly integrated electronic devices and electrical equipment are becoming prominent.In this work,“high-temperature solid-phase&diazonium salt decomposition”method is carried out to prepare benzidine-functionalized boron nitride(m-BN).Subsequently,m-BN/poly(pphenylene benzobisoxazole)nanofiber(PNF)nanocomposite paper with nacremimetic layered structures is prepared via sol–gel film transformation approach.The obtained m-BN/PNF nanocomposite paper with 50 wt%m-BN presents excellent thermal conductivity,incredible electrical insulation,outstanding mechanical properties and thermal stability,due to the construction of extensive hydrogen bonds andπ–πinteractions between m-BN and PNF,and stable nacre-mimetic layered structures.Itsλ∥andλ_(⊥)are 9.68 and 0.84 W m^(-1)K^(-1),and the volume resistivity and breakdown strength are as high as 2.3×10^(15)Ωcm and 324.2 kV mm^(-1),respectively.Besides,it also presents extremely high tensile strength of 193.6 MPa and thermal decomposition temperature of 640°C,showing a broad application prospect in high-end thermal management fields such as electronic devices and electrical equipment.
基金Supported by the National Natural Science Foundation of China (No. 20772035)the Natural Science Foundation of Guangdong Province (No. 5300082)
文摘Starting from(5S)-(L-menthyloxy)-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[(2S)-4-bromo-2-(L-menthyloxy)-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5(C20H32BrNO5,Mr = 446.37) was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249(16),b = 19.005(3),c = 19.719(3) ,V = 4693.7(10) 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F(000) = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections(I 2σ(I)).X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N(1),C(3),C(1),C(37) and O(7) region and N(2),C(28),C(27),C(30) and O(4) region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(no.2022R1A2C1006743)。
文摘Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite layers faces challenges due to the lack of understanding of the formation mechanism and the challenge of determining the impact of self-assembled architecture on anticorrosive properties.In this study,we aimed to enhance the corrosion resistance of the MgO layer produced by plasma electrolysis(PE)of AZ31 Mg alloy by incorporating WO_(3) with partially phosphorated poly(vinyl alcohol)(PPVA).Two types of porous MgO layers were produced using the PE process with an alkaline-phosphate electrolyte,one with and one without WO_(3) nanoparticles,which were subsequently immersed in an aqueous solution of PPVA.Incorporating PPVA into the WO_(3)-MgO layer resulted in hybrids being deposited in a fragmented manner,creating a“laminar reef-like structure”that sealed most of the structural defects in the layer.The PPVA-sealed WO_(3)-based coating exhibited superior corrosion resistance compared to the other samples.Computational analyses were employed to explore the mechanism underlying the formation of PPVA/WO_(3) hybrids on the MgO layer.These findings suggest that PPVA-WO_(3)-MgO hybrid coatings can potentially improve corrosion resistance in various fields.
基金supported by the National Key Research and Development Program of China(2022YFB4101800)National Natural Science Foundation of China(22278077,22108040)+2 种基金Key Program of Qingyuan Innovation Laboratory(00221004)Research Program of Qingyuan Innovation Laboratory(00523006)Natural Science Foundation of Fujian Province(2022J02019)。
文摘Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.
基金funding from the Natural Science Foundation of Hubei Province,China(Grant No.2022CFA031)supported by the Natural Science Foundation of China(Grant No.22309056).
文摘The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li^(+)migration.Herein,we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate(LiDFOB).The Li-salt anions(DFOB−)not only accelerate the ring-opening polymerization of tetrahydrofuran,but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li^(+)conductivity of electrolytes,which is favorable for Li^(+)transport kinetics at low temperatures.Applications of this polymer electrolyte in Li||LiFePO_(4)cells show 82.3%capacity retention over 1000 cycles at 30℃and endow stable discharge capacity at−30℃.Remarkably,the Li||LiFePO4 cells retain 52%of their room-temperature capacity at−20℃and 0.1 C.This rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.
基金supported by the Research Program funded by the SeoulTech(Seoul National University of Science and Technology).
文摘In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This study proposes a facile fabrication process for Poly(vinylidene fluoride)(PVDF)nanofiber(NF)mats incorporating additive and nonadditive physical modifications.Patterned PVDF NF mats are prepared by electrospinning using a metal mesh as the NF collector.As a negative triboelectric material,the TENG with the patterned PVDF NF mat exhibits superior performance owing to the engineered morphology of the contact layer.PVDF is crucial in TENGs owing to its superior ferroelectric properties and surface charge density when combined with specific electroceramics.Hence,the synergy of the physical modification methods is achieved by incorporating BaTiO3(BTO)nanoparticles(NPs)into the PVDF.By functionalizing BTO NPs with polydopamine,the TENG performance is further improved owing to the enhanced dispersion of NPs and improved crystallinity of the PVDF chains.Utilizing large NPs produces a nanopatterning effect on the NF surface,thereby resulting in the hierarchical structure of the NF mats.The source of the voltage signals from the TENG is analyzed using fast Fourier transform.
基金financially supported by the National Key R&D Program of China (2021YFA1501700)the National Science Foundation of China (22272114)+4 种基金the Fundamental Research Funds from Sichuan University (2022SCUNL103)the Funding for Hundred Talent Program of Sichuan University (20822041E4079)the NSFC (22102018 and 52171201)the Huzhou Science and Technology Bureau (2022GZ45)the Hefei National Research Center for Physical Sciences at the Microscale (KF2021005)。
文摘The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.
文摘The repairing effect of poly(N-vinylpyrrolidone-co-methacrylic acid)on permed or bleached damaged hair was studied.The combing and tensile strength of permed and bleached hair before and after treatment with the copolymer solution were tested,and the effects of the mass fraction of copolymer solution and immerseing time on the combing and tensile strength for permed or bleached damaged hair were investigated.The repair mechanism of permed or bleached damaged hair was also explored.The results show that when the immersing time is 3 hours,the tensile strength of the permed hair increases with the mass fraction of the copolymer solution Tensile strength within 0%-0.3%,but no obvious change is observed when250 Yield strength the mass fraction is over 0.3%.Therefore,the optimal mass 200 fraction of the copolymer solution for repairing the permed hair(cN/dtex)is 0.3%.Similarly,the optimal mass fraction of the copolymer 150strength/solution for repairing the bleached hair is 0.5%.Furthermore,the effects of immersing time on the tensile strength of the100Tensile damaged hair fibers were compared between the permed and90 bleached hair before and after treatment with the copolymer500.40.30.500.10.2 solution.Coincidentally,the optimal immersion time for permedw(P(NVP-co-MAA))/%or bleached damaged hair is both 2 hours.The tensile strength of the permed and bleached hair soaked in 0.3%and 0.5%copolymer solutions for 2 hours increases by 15.55%and 18.12%,respectively,compared to untreated hair.Through infrared spectroscopy analysis,it is found that the amide II band in hair fibers shifted to the blue after repair,with the wave number shift of 11.12 and 11.09 cm^(-1),which confirm the formation of hydrogen bonds in the hair samples.Additionally,the urea hydrogen bond disruption experiment demonstrates that urea does not disrupt the hydrogen bonds in untreated hair fibers,but prevents the formation of new hydrogen bonds in damaged hair fibers.It further validates that the improvement of the tensile strength of the copolymer treated damaged hair fibers is mainly due to the formation of hydrogen bonds.After treatment with the copolymer,the dry and wet combing friction decrease by 30.73%and 28.55%for the permed hair,and decrease by 28.55%and 24.83%for the bleached hairs,respectively.The scanning electron microscope shows that the copolymer can flatten the cuticle and fill the space between the raised cuticles.
基金supported by the National Natural Science Foundation of China(22008053,52002111)the Natural Science Foundation of Hebei Province(B2021208061,B2022208006,B2023208014)the Beijing Natural Science Foundation(Z200011).
文摘Gel-based polymer electrolytes are limited by the polarity of the residual solvent,which restricts the coupling-breaking behaviour during Li^(+)conduction,resulting in the Li^(+)transport kinetics being greatly affected.Here,we designed anion competitive gel polymer electrolyte(ACPE)by introducing lithium difluoro(oxalato)borate(LiDFOB)anion into the 1,3-dioxolane(DOL)in situ polymerisation system.ACPE enhances the ionic dipole interaction between Li^(+)and the solvent molecules and synergizes with Li^(+)across the solvation site of the polymer ethylene oxide(EO)unit,combination that greatly improves the Li^(+)transport efficiency.As a result,ACPE exhibits 1.12 mS cm^(−1)ionic conductivity and 0.75 Li^(+)transfer number at room temperature.Additionally,this intra-polymer solvation sheath allows preferential desolvation of DFOB−,which contributes to the formation of kinetically stable anion-derived interphase and effectively mitigates side reactions.Our results demonstrate that the assembled Li||NCM622 solid-state battery exhibits lifespan of over 300 cycles with average Coulombic efficiency of 98.8%and capacity retention of 80.3%.This study introduces a novel approach for ion migration and interface design,paving the way for high-safety and high-energy-density batteries.
基金supported by National Natural Science Foundation of China(Grant No.22209012).
文摘The interfacial instability of the poly(ethylene oxide)(PEO)-based electrolytes impedes the long-term cycling and further application of all-solid-state lithium metal batter-ies.In this work,we have shown an effective additive 1-adaman-tanecarbonitrile,which con-tributes to the excellent per-formance of the poly(ethylene oxide)-based electrolytes.Owing to the strong interaction of the 1-Adamantanecarboni-trile to the polymer matrix and anions,the coordination of the Li^(+)-EO is weakened,and the binding effect of anions is strengthened,thereby improving the Li^(+)conductivity and the electrochemical stability.The diamond building block on the surface of the lithium anode can sup-press the growth of lithium dendrites.Importantly,the 1-Adamantanecarbonitrile also regulates the formation of LiF in the solid electrolyte interface and cathode electrolyte interface,which contributes to the interfacial stability(especially at high voltages)and protects the electrodes,enabling all-solid-state batteries to cycle at high voltages for long periods of time.Therefore,the Li/Li symmetric cell undergoes long-term lithium plating/stripping for more than 2000 h.1-Adamantanecarbonitrile-poly(ethylene oxide)-based LFP/Li and 4.3 V Ni_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li all-solid-state batteries achieved stable cycles for 1000 times,with capacity retention rates reaching 85%and 80%,respectively.
文摘Poly(ADP-ribose)(PAR),a polymer of ADP-ribose,is synthesized by PAR po-lymerase and is crucial for the survival of cancer cells due to its vital functions in DNA repair and post-translational modifications.Beyond its supportive role,PAR also triggers cancer cell death by excessive accumulation of PAR leading to an energy crisis and parthanatos.This phenomenon underscores the potential of targeting PAR regulation as a novel anticancer strategy,and the rationale would present an engaging topic in the field of anticancer research.Therefore,this editorial provides an overview of the mechanisms determining cancer cell fate,emphasizing the central role of PAR.It further introduces promising methods for modulating PAR concentrations that may pave the way for innovative anticancer therapies.
基金supported by the National Natural Science Foundation of China(Grant Nos.51604089,51874110,22173066,and 21903058)Natural Science Foundation of Heilongjiang Province(Grant No.YQ2021B004).
文摘Polymer solid electrolytes(SPEs)based on the[solvate-Li+]complex structure have promising prospects in lithium metal batteries(LMBs)due to their unique ion transport mechanism.However,the solvation structure may compromise the mechanical performance and safety,hindering practical application of SPEs.In this work,a composite solid electrolyte(CSE)is designed through the organic-inorganic syner-gistic interaction among N,N-dimethylformamide(DMF),polycarbonate(PC),and Mg_(2)B_(2)O_(5) in poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP).Flame-retardant Mg_(2)B_(2)O_(5) nanowires provide non-flammability to the prepared CSEs,and the addition of PC improves the dispersion of Mg_(2)B_(2)O_(5) nanowires.Simultaneously,the organic-inorganic synergistic action of PC plasticizer and Mg_(2)B_(2)O_(5) nanowires pro-motes the dissociation degree of LiTFSI and reduces the crystallinity of PVDF-HFP,enabling rapid Li ion transport.Additionally,Raman spectroscopy and DFT calculations confirm the coordination between Mg atoms in Mg_(2)B_(2)O_(5) and N atoms in DMF,which exhibits Lewis base-like behavior attacking adjacent C-F and C-H bonds in PVDF-HFP while inducing dehydrofluorination of PVDF-HFP.Based on the syner-gistic coupling of Mg_(2)B_(2)O_(5),PC,and DMF in the PVDF-HFP matrix,the prepared CSE exhibits superior ion conductivity(9.78×10^(-4) s cm^(-1)).The assembled Li symmetric cells cycle stably for 3900 h at a current density of 0.1 mA cm^(-2) without short circuit.The LFP||Li cells assembled with PDL-Mg_(2)B_(2)O_(5)/PC CSEs show excellent rate capability and cycling performance,with a capacity retention of 83.3%after 1000 cycles at 0.5 C.This work provides a novel approach for the practical application of organic-inorganic Synergistic CSEs in LMBs.