The isolated hydrophilic black alder(Alnus glutinosa)bark extractives were characterized in terms of component and functional composition and converted at 150℃-170℃ into liquid green polyols using solvent-free and l...The isolated hydrophilic black alder(Alnus glutinosa)bark extractives were characterized in terms of component and functional composition and converted at 150℃-170℃ into liquid green polyols using solvent-free and lowtoxic base-catalyzed modification with propylene carbonate(PC).FTIR spectroscopy,HP-LC,GC,GPC,and wet chemistry methods were used to characterize the starting constituents,intermediate and final products of the reaction and to monitor the different pathways of PC conversion.The reaction of extractives as well as the model compounds,including catechol,xylose,PEG 400,and benzoic acid,with PC indicated the ability of OH groups of different origins present in the extractives to condense with equivalent amounts of PC.The polyols obtained consist of a copolymer fraction with one oxypropyl unit grafted per OH functionality of extractive components on average and oligo oxypropyl diols with a small number of carbonate linkages in the chain,obtained as a result of remaining PC homopolymerization.The domination of the oxypropylation mechanism vs.transcarbonation for PC ring opening was observed for both copolymerization and homopolymerization processes,making the process of oxypropylation with PC similar to that of conventional oxypropylation.At optimal reaction conditions,including a PC/OH ratio of 3.0 and a 24-h duration at 150°C,uniform polyols with low viscosity of~900 mPa·s^(-1),a biomass content of~27%,and an OHV of~500 mg KOH·g^(-1) were obtained.Increasing the temperature of modification allows shortening the process but drastically increases the polyol viscosity.At fixed temperature values,increasing the PC/OH ratio not only decreases the biomass content but also strongly prolongs the processing.The significantly increased duration of the process using PC as an alternative oxyalkylation agent compared to that of oxyalkylation with propylene oxide is a reasonable trade-off for using a safer and more environmentally friendly technology.展开更多
The activities of nickel supported on MCM-41 catalysts, prepared by co-impregnation with polyols （ethylene glycol, glycerol, xylitol, sorbitol and glucose）, were investigated by hydrogenation of naphthalene. Compare...The activities of nickel supported on MCM-41 catalysts, prepared by co-impregnation with polyols （ethylene glycol, glycerol, xylitol, sorbitol and glucose）, were investigated by hydrogenation of naphthalene. Compared with the conventional wetness impregnation, addition of moderate polyols into the metal nitrate support surface, resulting in formation of persion of the active phase and significant aqueous solution could enhance interaction with very small NiO particle size （〈5 nm）, high discatalytic activity. Particle size of Ni^0 decreased from 36.1 nm to below 5 nm; meanwhile the complete hydrogenation of naphthalene was dependent on the Ni^0 particle size. The hydrogenation activities of the catalysts prepared by co-impregnation with polyols were very high with 100% conversion even at iow temperature of 55 ℃.展开更多
Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by...Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.展开更多
Three kinds of tung oil-based structural flame retardants polyols(TOFPs) were prepared by new methods in this paper. First, tung oil was used to produce monoglyceride and diglyceride by transesterification with glycer...Three kinds of tung oil-based structural flame retardants polyols(TOFPs) were prepared by new methods in this paper. First, tung oil was used to produce monoglyceride and diglyceride by transesterification with glycerol by sodium methoxide. The products after transesterification were epoxidized by peracetic acid which was in-situ generated from acetic acid and hydrogen peroxide in the presence of sulfuric acid catalyst. And then, TOFPs were prepared from epoxidized alcoholysis tung oil(EGTO) with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO), diethyl phosphate(DEP) and diethanolamine(DEA) by ring-opening reactions, respectively. GPC was used to evaluate the conversion rate, at optimum reaction conditions, selectivity for monoglyceride in transesterification. The influence of different parameters such as temperature, mole ratio or mass ratio on the conversion rate of transesterification and epoxidation were investigated. The molecular structures of TOFPs were characterized by FTIR and ~1HNMR. Finally, tung oil-based polyurethane foams(TOPUFs) were prepared by a one-shot process using TOFPs with polyisocyanate. The LOI values of TOPUFs whose content of DOPO-EGTO,DEP-EGTO and DEA-EGTO were 100 wt% can reach to 26.2%, 25.1%, and 24.4%, respectively.展开更多
As the oil crisis and environment concerning deepen, the uses of renewable resources have attracted considerable attention. Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxy...As the oil crisis and environment concerning deepen, the uses of renewable resources have attracted considerable attention. Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxylation of soybean oil, alternative to petroleum- based process. The transformation can afford soybean oil polyol in excellent yield with a hydroxyl number up to 467.7 mg KOH/g in the presence of OsO4 as catalyst and NMO as oxidant. The major advantages of this approach are： two hydroxyl groups can be readily added to one double bond, replacing conventional two-step methods by an epoxidation step and then a ring opening step; a wide range of hydroxyl numbers can be obtained via varying catalyst loadings; the reaction can be performed at room temperature. The chemical structure of the polyol prepared was further characterized by chemical methods （hydroxyl number and iodine number） and spectra （1H NMR and FFIR spectroscopy）, which confirmed the cleavage of the double bonds and the produce of hydroxyl groups.展开更多
A series of self-reducing bifunctional Ni-W/SBA-15 catalysts were synthesized using biomass-based carbon source as the reducing agent without conventional further reduction step. The self-reducing catalysts were perfo...A series of self-reducing bifunctional Ni-W/SBA-15 catalysts were synthesized using biomass-based carbon source as the reducing agent without conventional further reduction step. The self-reducing catalysts were performed on the hydrogenolysis of cellulose to low carbon polyols. The effects of calcination temperature and metallic loading contents for cellulose hydrogenolysis reaction were investigated detailedly.The optimal calcination temperature was found to be 673 K by TG analysis. The active metal nanoparticles with a better dispersion were observed using SEM and element mapping technology. The yield of low carbon polyols using the catalyst with the receipt of 10%Ni-15%W/SBA-15-673 K can reach as high as68.14%, of which the ethylene glycol(EG) accounts for 61.04%.展开更多
In order to prepare the polyol with all bio-based components as raw materials,cottonseed oil was first epoxidized by peroxyformic acid generated in situ from hydrogen peroxide and formic acid,and the cottonseed oil ba...In order to prepare the polyol with all bio-based components as raw materials,cottonseed oil was first epoxidized by peroxyformic acid generated in situ from hydrogen peroxide and formic acid,and the cottonseed oil based polyols with variable hydroxyl value were then prepared by the ring-opening of epoxidized cottonseed oil with sorbitol,which is a multi-functional hydroxyl compound derived from a natural source.The chemical structure of the products was characterized with FTIR analysis, and the residual epoxy oxygen content and hydroxyl value of the polyol versus the ring-opening time were investigated.展开更多
Carbon-coated lithium manganese silicate （Li2MnSiO4/C） nanoparticles were synthesized by polyol process. X-ray diffraction （XRD） patterns of the obtained materials exhibit a good fit with that of the Li2MnSiO4 pha...Carbon-coated lithium manganese silicate （Li2MnSiO4/C） nanoparticles were synthesized by polyol process. X-ray diffraction （XRD） patterns of the obtained materials exhibit a good fit with that of the Li2MnSiO4 phase. Field emission scanning electron microscopy （FESEM） images of the obtained samples show that the particle size is only tens of nanometers. The high resolution transmission electron microscopy （HRTEM） analysis shows that the Li2MnSiO4 nanoparticles are surrounded by a very thin film of amorphous carbon. The composite prepared through polyol process shows good performance as cathode materials in lithium cells at room temperature. The charge capacity of the Li2MnSiO4/C samples is 219 mAh/g （about 1.3 Li^＋ per unit formula extracted）, and the discharge capacity is 132 mAh/g （about 0.8 Li^＋ per unit formula inserted） in the first cycle in the voltage range of 1.5-4.8 V. A good capacity cycling maintenance of 81.8% after 10 cycles was obtained.展开更多
In the present study we report on changes in irritable bowel syndrome-severity scoring system (IBS-SSS) and irritable bowel syndrome-quality of life (IBS-QoL) in 19 IBS patients, aged 18 to 74 years (F/M: 14/5), durin...In the present study we report on changes in irritable bowel syndrome-severity scoring system (IBS-SSS) and irritable bowel syndrome-quality of life (IBS-QoL) in 19 IBS patients, aged 18 to 74 years (F/M: 14/5), during 12 wk registering their symptoms on the web-application (www.ibs.constant-care.dk). During a control period of the first 6-wk patients were asked to register their IBS-SSS and IBS-QoL on the web-application weekly without receiving any intervention. Thereafter, low fermentable oligo-, di-, mono-saccharides and polyols (FODMAP) diet (LFD) was introduced for the next 6 wk while continuing the registration. Though a small sample size a significant improvement in disease activity (IBS-SSS) was observed during both the control period, median: 278 (range: 122-377), P = 0.02, and subsequently during the LFD period, median: 151 (range: 29-334), P < 0.01. The IBS-QoL solely changed significantly during the LFD period, median: 67 (37-120), P < 0.01. The significant reduction in disease activity during the control period shows a positive effect of the web-application on IBS symptoms when presented as a “traffic light”. However adding the diet reduced IBS-SSS to < 150, inactive to mild symptoms. In the future results from larger scale trials are awaited.展开更多
In diabetes mellitus, the polyol pathway is highly active and consumes approximately 30% glucose in the body. This pathway contains 2 reactions catalyzed by aldose reductase(AR) and sorbitol dehydrogenase, respectivel...In diabetes mellitus, the polyol pathway is highly active and consumes approximately 30% glucose in the body. This pathway contains 2 reactions catalyzed by aldose reductase(AR) and sorbitol dehydrogenase, respectively. AR reduces glucose to sorbitol at the expense of NADPH, while sorbitol dehydrogenase converts sorbitol to fructose at the expense of NAD+, leading to NADH production. Consumption of NADPH, accumulation of sorbitol, and generation of fructose and NADH have all been implicated in the pathogenesis of diabetes and its complications. In this review, the roles of this pathway in NADH/NAD+redox imbalance stress and oxidative stress in diabetes are highlighted. A potential intervention using nicotinamide riboside to restore redox balance as an approach to fighting diabetes is also discussed.展开更多
A new sesquiterpene polyol ester was isolated from the leaves of Celastrus angulatus. Its structure was determined as 1 (beta), 2 (beta), 9 (a) -triacetoxy-8 (a) -((a) -hydroxyl-isobutyryloxy)-15-benzoyloxy-4 (a) -hyd...A new sesquiterpene polyol ester was isolated from the leaves of Celastrus angulatus. Its structure was determined as 1 (beta), 2 (beta), 9 (a) -triacetoxy-8 (a) -((a) -hydroxyl-isobutyryloxy)-15-benzoyloxy-4 (a) -hydroxy-dihydroagarofuran by means of NMR, MS and IR spectral analysis. Preliminary biological study on antitumor activity revealed that this compound showed strong nonselective cytotoxicity against four of the NCI panel cell lines.展开更多
Recently, hyperbranched polymers(HBPs), which differ significantly in structure and properties from linear, cross-linked and branched analogs, have become increasingly important. HBP have a spatial unloaded core and a...Recently, hyperbranched polymers(HBPs), which differ significantly in structure and properties from linear, cross-linked and branched analogs, have become increasingly important. HBP have a spatial unloaded core and a shell of branched monomer units(dendrons), in which functional groups are predominantly located in the surface layer. The size of macromolecules ranges from 2 nm to 100 nm. Currently, there are a fairly large number of publications in the literature devoted to the modification of hyperbranched polyester polyols with various functional groups and the assessment of the potential for their use. However, there are no review articles on this topic in recent years. In this regard, it is relevant to generalize the latest achievements in the field of synthesis, properties and application of hyperbranched polyester polyols with terminal oxygen, nitrogen, silicon, sulfur and organophosphorus fragments. The advantage of hyperbranched polyester polyols of the Boltorn H series is their industrial availability, biodegradability, nanoscale, non-toxicity and high solubility in various polar solvents due to short monomer units, as well as the presence of reactive terminal hydroxyl groups. Functionalization of hyperbranched polyester polyols at hydroxyl groups is mainly carried out by addition of acid anhydrides, iso(thio)cyanates, alkenes, lactides, lactones, lactams, epoxy compounds or reactions with halogenated compounds(alkyl halides, acid chlorides). In some cases, for the functionalization of polyester polyols special linkers are used, such as acid chlorides of unsaturated or dicarboxylic acids, diisocyanates, etc., which provide covalent bonding of the hyperbranched polymer with the target functional group. The obtained derivatives of hyperbranched polyesters are widely used in such areas as biomedicine, pharmacy, paints and varnishes, they are also used as catalysts, membranes, multifunctional coatings, plasticizers and polymer stabilizers.展开更多
Phosphate material LiMnPO4 is popular for its high energy density(697 W·h·kg^(-1))and safety.When LiMnPO_(4) crystal grows,the potential barrier along b and c axis is strong,which makes the crystal grow alon...Phosphate material LiMnPO4 is popular for its high energy density(697 W·h·kg^(-1))and safety.When LiMnPO_(4) crystal grows,the potential barrier along b and c axis is strong,which makes the crystal grow along b axis to form a one-dimensional chain structure.However,the main migration channel of lithium ions in olivine structure is plane(010).By shortening the growth in the direction of b axis and enhancing the diffusion along the directions of a and c,two-dimensional nanosheets that are more conducive to the migration of lithium ions are formed.The dosage of polyols is the key factor guiding the dispersion of the crystals to the(010)plane.X-ray diffraction(XRD),Scanning electron microscopy(SEM),transmission electron microscopy(TEM)and other means are used to characterize the samples.After experiments,we found that when the ratio of polyol/water was 2:1,the morphology of the synthesized sample was 20–30 nm thick nanosheets,which had the best electrochemical performance.At 0.1C,the discharge specific capacity reaches 148.9 mA·h·g^(-1),still reaches 144.3 mA·h·g^(-1) at the 50th cycle.and there is still 112.5 mA·h·g^(-1) under high rate(5C).This is thanks to the good dispersion of the material in the direction of the crystal plane(010).This can solve the problem of low conductivity and ionic mobility of phosphate materials.展开更多
Catalytic conversion of glucose, the most abundant carbohydrate, to chemicals of petroleum origin has great desirability in terms of sustainability and industrial implementation. In this work, we attempted to exploit ...Catalytic conversion of glucose, the most abundant carbohydrate, to chemicals of petroleum origin has great desirability in terms of sustainability and industrial implementation. In this work, we attempted to exploit the vanadium-based catalysts with high retro-aldol condensation(RAC) activity for the synthesis of small polyols from glucose. Vanadium species incorporated or anchored beta zeolites were found to work effectively in synergy with 1 Ru/AC to produce hydroxyacetone(HA) as the major product(34%)in a semi-continuously stirred tank reactor under 5% glucose concentration. Catalyst characterization by UV-vis and Raman spectral analysis revealed vanadium species mainly stayed in the incorporated form(tetrahedral) at 0.5% of loading and in the supported form(octahedral) at higher loadings up to 8%. Pyridine infrared spectra and temperature programmed desorption of NH3 revealed weak Lewis acid sites in dominance. Vanadium species in the catalysts displayed multiple catalytic roles(isomerization and RAC reaction, and synergism with the hydrogenation catalyst) in the synthesis of HA from glucose. Structureactivity correlation pointed out that the catalytic activity of vanadium species is not dependent on it coordination status, nevertheless, the adjacent vanadium atoms could possibly improve the isomerization rate over the RAC rate in favor of high yield of HA. The catalyst system is recyclable to at least five times without any considerable loss in its activity and structural integrity. The results presented here provide a promising route for the sustainable production of HA and polyols from carbohydrates by using a highly selective vanadium catalyst.展开更多
基金financial support from the Latvian Council of Science,Project No.lzp-2021/1-0207.
文摘The isolated hydrophilic black alder(Alnus glutinosa)bark extractives were characterized in terms of component and functional composition and converted at 150℃-170℃ into liquid green polyols using solvent-free and lowtoxic base-catalyzed modification with propylene carbonate(PC).FTIR spectroscopy,HP-LC,GC,GPC,and wet chemistry methods were used to characterize the starting constituents,intermediate and final products of the reaction and to monitor the different pathways of PC conversion.The reaction of extractives as well as the model compounds,including catechol,xylose,PEG 400,and benzoic acid,with PC indicated the ability of OH groups of different origins present in the extractives to condense with equivalent amounts of PC.The polyols obtained consist of a copolymer fraction with one oxypropyl unit grafted per OH functionality of extractive components on average and oligo oxypropyl diols with a small number of carbonate linkages in the chain,obtained as a result of remaining PC homopolymerization.The domination of the oxypropylation mechanism vs.transcarbonation for PC ring opening was observed for both copolymerization and homopolymerization processes,making the process of oxypropylation with PC similar to that of conventional oxypropylation.At optimal reaction conditions,including a PC/OH ratio of 3.0 and a 24-h duration at 150°C,uniform polyols with low viscosity of~900 mPa·s^(-1),a biomass content of~27%,and an OHV of~500 mg KOH·g^(-1) were obtained.Increasing the temperature of modification allows shortening the process but drastically increases the polyol viscosity.At fixed temperature values,increasing the PC/OH ratio not only decreases the biomass content but also strongly prolongs the processing.The significantly increased duration of the process using PC as an alternative oxyalkylation agent compared to that of oxyalkylation with propylene oxide is a reasonable trade-off for using a safer and more environmentally friendly technology.
基金V. ACKNOWLEDGMENTS This work was supported by the National High-Tech Research and Development 863 Program of China （No.2012AA101806）, the National Natural Science Foundation of China （No.21306195 and No.51276183）, and the National Key Basic Research Program 973 Project from Ministry of Science and Technology of China （No.2012CB215304）.
文摘The activities of nickel supported on MCM-41 catalysts, prepared by co-impregnation with polyols （ethylene glycol, glycerol, xylitol, sorbitol and glucose）, were investigated by hydrogenation of naphthalene. Compared with the conventional wetness impregnation, addition of moderate polyols into the metal nitrate support surface, resulting in formation of persion of the active phase and significant aqueous solution could enhance interaction with very small NiO particle size （〈5 nm）, high discatalytic activity. Particle size of Ni^0 decreased from 36.1 nm to below 5 nm; meanwhile the complete hydrogenation of naphthalene was dependent on the Ni^0 particle size. The hydrogenation activities of the catalysts prepared by co-impregnation with polyols were very high with 100% conversion even at iow temperature of 55 ℃.
基金Supported by the Natural Science Foundation of China(51172064)the Scientific and Technological Development Projects,Science and Technology Department of Henan Province,China(112300410011)
基金supported by a grant from the National Natural Science Foundation of China,No.81060141
文摘Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.
基金Supported by the National Natural Science Foundation of China(31670577,31670578,31570563)
文摘Three kinds of tung oil-based structural flame retardants polyols(TOFPs) were prepared by new methods in this paper. First, tung oil was used to produce monoglyceride and diglyceride by transesterification with glycerol by sodium methoxide. The products after transesterification were epoxidized by peracetic acid which was in-situ generated from acetic acid and hydrogen peroxide in the presence of sulfuric acid catalyst. And then, TOFPs were prepared from epoxidized alcoholysis tung oil(EGTO) with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO), diethyl phosphate(DEP) and diethanolamine(DEA) by ring-opening reactions, respectively. GPC was used to evaluate the conversion rate, at optimum reaction conditions, selectivity for monoglyceride in transesterification. The influence of different parameters such as temperature, mole ratio or mass ratio on the conversion rate of transesterification and epoxidation were investigated. The molecular structures of TOFPs were characterized by FTIR and ~1HNMR. Finally, tung oil-based polyurethane foams(TOPUFs) were prepared by a one-shot process using TOFPs with polyisocyanate. The LOI values of TOPUFs whose content of DOPO-EGTO,DEP-EGTO and DEA-EGTO were 100 wt% can reach to 26.2%, 25.1%, and 24.4%, respectively.
文摘As the oil crisis and environment concerning deepen, the uses of renewable resources have attracted considerable attention. Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxylation of soybean oil, alternative to petroleum- based process. The transformation can afford soybean oil polyol in excellent yield with a hydroxyl number up to 467.7 mg KOH/g in the presence of OsO4 as catalyst and NMO as oxidant. The major advantages of this approach are： two hydroxyl groups can be readily added to one double bond, replacing conventional two-step methods by an epoxidation step and then a ring opening step; a wide range of hydroxyl numbers can be obtained via varying catalyst loadings; the reaction can be performed at room temperature. The chemical structure of the polyol prepared was further characterized by chemical methods （hydroxyl number and iodine number） and spectra （1H NMR and FFIR spectroscopy）, which confirmed the cleavage of the double bonds and the produce of hydroxyl groups.
基金supported by scientific research project of Zhejiang Provincial Education Department(Grant No.Y20112088,China)Science and technology project of Zhejiang Province(Grant No.2011R09028-10,China)
文摘A series of self-reducing bifunctional Ni-W/SBA-15 catalysts were synthesized using biomass-based carbon source as the reducing agent without conventional further reduction step. The self-reducing catalysts were performed on the hydrogenolysis of cellulose to low carbon polyols. The effects of calcination temperature and metallic loading contents for cellulose hydrogenolysis reaction were investigated detailedly.The optimal calcination temperature was found to be 673 K by TG analysis. The active metal nanoparticles with a better dispersion were observed using SEM and element mapping technology. The yield of low carbon polyols using the catalyst with the receipt of 10%Ni-15%W/SBA-15-673 K can reach as high as68.14%, of which the ethylene glycol(EG) accounts for 61.04%.
文摘In order to prepare the polyol with all bio-based components as raw materials,cottonseed oil was first epoxidized by peroxyformic acid generated in situ from hydrogen peroxide and formic acid,and the cottonseed oil based polyols with variable hydroxyl value were then prepared by the ring-opening of epoxidized cottonseed oil with sorbitol,which is a multi-functional hydroxyl compound derived from a natural source.The chemical structure of the products was characterized with FTIR analysis, and the residual epoxy oxygen content and hydroxyl value of the polyol versus the ring-opening time were investigated.
文摘Carbon-coated lithium manganese silicate （Li2MnSiO4/C） nanoparticles were synthesized by polyol process. X-ray diffraction （XRD） patterns of the obtained materials exhibit a good fit with that of the Li2MnSiO4 phase. Field emission scanning electron microscopy （FESEM） images of the obtained samples show that the particle size is only tens of nanometers. The high resolution transmission electron microscopy （HRTEM） analysis shows that the Li2MnSiO4 nanoparticles are surrounded by a very thin film of amorphous carbon. The composite prepared through polyol process shows good performance as cathode materials in lithium cells at room temperature. The charge capacity of the Li2MnSiO4/C samples is 219 mAh/g （about 1.3 Li^＋ per unit formula extracted）, and the discharge capacity is 132 mAh/g （about 0.8 Li^＋ per unit formula inserted） in the first cycle in the voltage range of 1.5-4.8 V. A good capacity cycling maintenance of 81.8% after 10 cycles was obtained.
文摘In the present study we report on changes in irritable bowel syndrome-severity scoring system (IBS-SSS) and irritable bowel syndrome-quality of life (IBS-QoL) in 19 IBS patients, aged 18 to 74 years (F/M: 14/5), during 12 wk registering their symptoms on the web-application (www.ibs.constant-care.dk). During a control period of the first 6-wk patients were asked to register their IBS-SSS and IBS-QoL on the web-application weekly without receiving any intervention. Thereafter, low fermentable oligo-, di-, mono-saccharides and polyols (FODMAP) diet (LFD) was introduced for the next 6 wk while continuing the registration. Though a small sample size a significant improvement in disease activity (IBS-SSS) was observed during both the control period, median: 278 (range: 122-377), P = 0.02, and subsequently during the LFD period, median: 151 (range: 29-334), P < 0.01. The IBS-QoL solely changed significantly during the LFD period, median: 67 (37-120), P < 0.01. The significant reduction in disease activity during the control period shows a positive effect of the web-application on IBS symptoms when presented as a “traffic light”. However adding the diet reduced IBS-SSS to < 150, inactive to mild symptoms. In the future results from larger scale trials are awaited.
基金National Institutes of Health,Grant/Award Number:R01NS079792UNTHSC Seed Grants,Grant/Award Number:RI10015 and RI10039
文摘In diabetes mellitus, the polyol pathway is highly active and consumes approximately 30% glucose in the body. This pathway contains 2 reactions catalyzed by aldose reductase(AR) and sorbitol dehydrogenase, respectively. AR reduces glucose to sorbitol at the expense of NADPH, while sorbitol dehydrogenase converts sorbitol to fructose at the expense of NAD+, leading to NADH production. Consumption of NADPH, accumulation of sorbitol, and generation of fructose and NADH have all been implicated in the pathogenesis of diabetes and its complications. In this review, the roles of this pathway in NADH/NAD+redox imbalance stress and oxidative stress in diabetes are highlighted. A potential intervention using nicotinamide riboside to restore redox balance as an approach to fighting diabetes is also discussed.
文摘A new sesquiterpene polyol ester was isolated from the leaves of Celastrus angulatus. Its structure was determined as 1 (beta), 2 (beta), 9 (a) -triacetoxy-8 (a) -((a) -hydroxyl-isobutyryloxy)-15-benzoyloxy-4 (a) -hydroxy-dihydroagarofuran by means of NMR, MS and IR spectral analysis. Preliminary biological study on antitumor activity revealed that this compound showed strong nonselective cytotoxicity against four of the NCI panel cell lines.
文摘Recently, hyperbranched polymers(HBPs), which differ significantly in structure and properties from linear, cross-linked and branched analogs, have become increasingly important. HBP have a spatial unloaded core and a shell of branched monomer units(dendrons), in which functional groups are predominantly located in the surface layer. The size of macromolecules ranges from 2 nm to 100 nm. Currently, there are a fairly large number of publications in the literature devoted to the modification of hyperbranched polyester polyols with various functional groups and the assessment of the potential for their use. However, there are no review articles on this topic in recent years. In this regard, it is relevant to generalize the latest achievements in the field of synthesis, properties and application of hyperbranched polyester polyols with terminal oxygen, nitrogen, silicon, sulfur and organophosphorus fragments. The advantage of hyperbranched polyester polyols of the Boltorn H series is their industrial availability, biodegradability, nanoscale, non-toxicity and high solubility in various polar solvents due to short monomer units, as well as the presence of reactive terminal hydroxyl groups. Functionalization of hyperbranched polyester polyols at hydroxyl groups is mainly carried out by addition of acid anhydrides, iso(thio)cyanates, alkenes, lactides, lactones, lactams, epoxy compounds or reactions with halogenated compounds(alkyl halides, acid chlorides). In some cases, for the functionalization of polyester polyols special linkers are used, such as acid chlorides of unsaturated or dicarboxylic acids, diisocyanates, etc., which provide covalent bonding of the hyperbranched polymer with the target functional group. The obtained derivatives of hyperbranched polyesters are widely used in such areas as biomedicine, pharmacy, paints and varnishes, they are also used as catalysts, membranes, multifunctional coatings, plasticizers and polymer stabilizers.
基金financial support from Natural Science Foundation of Guangdong Province(2018A030313423)Key Research and Development Program of Guangdong Province(2020B090919005)Pearl River Science and Technology New Star Project(201806010039).
文摘Phosphate material LiMnPO4 is popular for its high energy density(697 W·h·kg^(-1))and safety.When LiMnPO_(4) crystal grows,the potential barrier along b and c axis is strong,which makes the crystal grow along b axis to form a one-dimensional chain structure.However,the main migration channel of lithium ions in olivine structure is plane(010).By shortening the growth in the direction of b axis and enhancing the diffusion along the directions of a and c,two-dimensional nanosheets that are more conducive to the migration of lithium ions are formed.The dosage of polyols is the key factor guiding the dispersion of the crystals to the(010)plane.X-ray diffraction(XRD),Scanning electron microscopy(SEM),transmission electron microscopy(TEM)and other means are used to characterize the samples.After experiments,we found that when the ratio of polyol/water was 2:1,the morphology of the synthesized sample was 20–30 nm thick nanosheets,which had the best electrochemical performance.At 0.1C,the discharge specific capacity reaches 148.9 mA·h·g^(-1),still reaches 144.3 mA·h·g^(-1) at the 50th cycle.and there is still 112.5 mA·h·g^(-1) under high rate(5C).This is thanks to the good dispersion of the material in the direction of the crystal plane(010).This can solve the problem of low conductivity and ionic mobility of phosphate materials.
基金supported by the National Natural Science Foundation of China (nos. 21306191 21376239+1 种基金 21690080 21690081)
文摘Catalytic conversion of glucose, the most abundant carbohydrate, to chemicals of petroleum origin has great desirability in terms of sustainability and industrial implementation. In this work, we attempted to exploit the vanadium-based catalysts with high retro-aldol condensation(RAC) activity for the synthesis of small polyols from glucose. Vanadium species incorporated or anchored beta zeolites were found to work effectively in synergy with 1 Ru/AC to produce hydroxyacetone(HA) as the major product(34%)in a semi-continuously stirred tank reactor under 5% glucose concentration. Catalyst characterization by UV-vis and Raman spectral analysis revealed vanadium species mainly stayed in the incorporated form(tetrahedral) at 0.5% of loading and in the supported form(octahedral) at higher loadings up to 8%. Pyridine infrared spectra and temperature programmed desorption of NH3 revealed weak Lewis acid sites in dominance. Vanadium species in the catalysts displayed multiple catalytic roles(isomerization and RAC reaction, and synergism with the hydrogenation catalyst) in the synthesis of HA from glucose. Structureactivity correlation pointed out that the catalytic activity of vanadium species is not dependent on it coordination status, nevertheless, the adjacent vanadium atoms could possibly improve the isomerization rate over the RAC rate in favor of high yield of HA. The catalyst system is recyclable to at least five times without any considerable loss in its activity and structural integrity. The results presented here provide a promising route for the sustainable production of HA and polyols from carbohydrates by using a highly selective vanadium catalyst.
