Developing efficient photocatalysts to address collaborative energy and environmental crises still faces significant challenges.In this report,we present a highly efficient MXene–based photocatalyst,which is combined...Developing efficient photocatalysts to address collaborative energy and environmental crises still faces significant challenges.In this report,we present a highly efficient MXene–based photocatalyst,which is combined with MoS_(2)nano patches and TiO_(2)/Ti_(3)C_(2)(TTC)nanowires through hydrothermal treatment.Of all the composites tested,the optimized photocatalyst gave a remarkable H_(2)and revolving polylactic acid(PLA)into pyruvic acid(PA).Achieving a remarkable H_(2)evolution rate of 637.1 and 243.2μmol g^(−1)h^(−1),in the presence of TEOA and PLA as a sacrificial reagent under UV-vis(λ≥365 nm)light irradiation.The improved photocatalytic activity is a result of the combination of dual cocatalyst on the surface of TTC photocatalyst,which create an ideal synergistic effect for the generation of PA and the production of H_(2)simultaneously.The MoS_(2)TiO_(2)/Ti_(3)C_(2)(MTT)composite can generate more photoexcited charge carriers,leading to the generation of more active radicals,which may enhance the system's photocatalytic activity.This work aims at demonstrating its future significance and guide the scientific community towards a more efficient approach to commercializing H_(2)through photocatalysis.展开更多
The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to...The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.展开更多
This study examined the effects of pasteurization(PAS),ultrasonic sterilization(ULS),and microwave sterilization(MWS)on the quality and storage characteristics of brine-fermented tofu(BFT)and fermented tofu(FT).Compar...This study examined the effects of pasteurization(PAS),ultrasonic sterilization(ULS),and microwave sterilization(MWS)on the quality and storage characteristics of brine-fermented tofu(BFT)and fermented tofu(FT).Comparative analysis revealed that MWS had a negligible detrimental effect on the structural integrity and organoleptic properties of BFT and FT,while effectively maintaining its water-holding capacity(WHC)and exhibiting the least impact on its texture.In contrast,PAS and ULS increased hardness and chewiness significantly(P<0.05),but ULS also enhanced the brightness of tofu.Throughout the storage period,the WHC,elasticity,and sensory properties of tofu generally decreased,whereas the hardness and chewiness increased.PAS-BFT and MWS-FT maintained sensory quality for the longest periods of 14 and 12 days respectively,and could be decomposed to more small molecule peptides within 0–8 days and 0–6 days,which are more easily to be absorbed by the body.The findings discovered that MWS is the most suitable method for sterilization of tofu,with superior capability in maintaining the quality,extending shelf life,and improving digestibility of tofu.展开更多
Photocatalytic selective synthesis of lactic acid(LA)from biomass sugars with a single heterogeneous catalyst is promising but challenging due to the multiple reaction steps involved.Herein,a K-doped C-rich red polyme...Photocatalytic selective synthesis of lactic acid(LA)from biomass sugars with a single heterogeneous catalyst is promising but challenging due to the multiple reaction steps involved.Herein,a K-doped C-rich red polymerized carbon nitride(RPCN)photocatalyst with uniform K/C dual sites was constructed by a molten salt template method,which was highly efficient for cascade isomerization dehydration of glucose to LA with>90%selectivity under visible light and gentle conditions.Control experiments and theoretical calculations expounded that the introduced K/C dual sites could improve the light capture ability and photogenerated charge separation efficiency,while the K species provided sufficient Lewis acid sites(adsorption sites)for the isomerization of glucose to fructose.Meanwhile,the introduced C sites that substitute N atoms could promote electrons to be captured by adsorbed oxygen for selective generation of superoxide radicals,which was highly efficient for the scission of the C3-C4 bond in fructose,exclusively furnishing LA.Importantly,the RPCN photocatalyst was also suitable for the photocatalytic upgrading of various biomass saccharides into LA with high yields of 81.3%-95.3%and could be recycled for five consecutive cycles.The tailored construction of dual sites by localization of space charge lightens an avenue for multi-step conversion of biomass with pronounced selectivity.展开更多
Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and ut...Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and utilization of near-infrared light,accounting for 50%of sunlight.Here,a molten salt-assisted in-plane“stitching”and interlayer“cutting”protocol is developed for constructing a highly crystalline carbon nitride catalyst containing structural oxygen(HC-CN).HC-CN is highly efficient for the photothermal cascade transformation of biomass-derived glucose into lactic acid(LA)with an unprecedented yield(94.3%)at 25°C under full-spectrum light irradiation within 50 min,which is also applicable to quantitatively photo-upgrading various saccharides.Theoretical calculations expound that the light-induced glucose-to-catalyst charge transfer can activate the Cβ-H bond to promote the rate-determining step of intramolecular hydrogen shift in glucose-to-fructose isomerization.Meanwhile,the introduced structural oxygen in HC-CN can not only facilitate the local electric field formation to achieve rapid charge transport/separation and regulate selective·O^(-)_(2)generation for oriented C3-C4 bond cleavage of fructose but also narrow the energy band gap to broaden the light absorption range of HC-CN,contributing to enhanced LA production without exogenous heating.Moreover,HC-CN is highly recyclable and exhibits negligible environmental burden and low energy consumption,as disclosed by the life cycle assessment.Tailored construction of full-spectrum light adsorption and versatile reaction sites provides a reference for implementing multi-step biomass and organic conversion processes under mild conditions.展开更多
This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By m...This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By means of an organic synthesis technique,epoxidized soybean oil(ESO)is chemically grafted to PLA to synthesize ESO chemically plastically modified PLA,abbreviated ECP.To fabricate PLA/ECP/n-MgO composite materials,ECP acts as a plasticizer and a compatibilizer simultaneously,and n-MgO acts as an enhancer.Then scanning electron microscopy,X-ray diffraction,differential scanning calorimetry,universal tester,and antibacterial research were exploited to characterize the morphology,thermal resistance,mechanical properties,and antibacterial performance of PLA/ECP/n-MgO composites.The experimental results show that ECP acts as a plasticizer by causing heterogeneous nucleation,which increases PLA's crystallinity.Evenly distributed n-MgO can greatly improve PLA's antibacterial qualities.Furthermore,ECP and n-MgO work together to improve the positive aspects of PLA/ECP/n-MgO composites,with PLA/ECP/n-MgO 100/1/0.5 composites having the best overall properties.While improving the mechanical performance and toughness of PLA,this work offers a prospective approach and foundational database for the creation of multifunctional biodegradable composites.展开更多
Hyperuricemia(HUA)is characterized by elevated levels of uric acid(UA)in the bloodstream,resulting from either excessive production or insufficient excretion of UA within the body.If left untreated,progressive or pers...Hyperuricemia(HUA)is characterized by elevated levels of uric acid(UA)in the bloodstream,resulting from either excessive production or insufficient excretion of UA within the body.If left untreated,progressive or persistent HUA can lead to gout,causing significant harm to human health.Lactic acid bacteria(LAB),generally recognized as safe(GRAS)probiotics,have been shown to alleviate symptoms associated with gastrointestinal disorders such as irritable bowel syndrome and inflammatory bowel disease while supporting overall bodily functions and health.Recently,LAB has emerged as a potentially safe,cost-effective and efficient treatment for HUA.This comprehensive review aims to explore the current literature on the mechanisms through which LAB controls HUA.These mechanisms include suppressing purine metabolism,absorbing purine compounds,modulating microbiota to maintain host global purine homeostasis,reducing intestinal permeability,producing metabolites that alleviate HUA symptoms,promoting the expression of urate excretory proteins and inhibiting the expression of urate reabsorption proteins.The findings presented in this review provide a framework for further investigation into how probiotic LAB can alleviate HUA by influencing UA metabolism and elucidating their underlying action mechanisms.展开更多
To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)proc...To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)process that can produce pure PLA with excellent mechanical properties.The MDP process generates a dynamic stretching effect by regulating the application and release of pressure,prompting disordered molecular chains to be arranged regularly along the direction of the dynamic force field.This promoted the formation of more ordered crystal forms(α-form)and strengthened the connection between the crystalline and amorphous regions.Results show that after MDP treatment,the tensile strength and strain at break of MDP-PLA are significantly improved,reaching 91.6 MPa and 80.1%respectively,which are 49.4%higher and 10 times higher than those of the samples before treatment.The mechanical properties of MDP-PLA can be regulated as needed by adjusting the cycle times and peak pressure.In addition,through a systematic study of the structural evolution of MDP-PLA,the performance regulation mechanism of the MDP process was thoroughly investigated,and the internal relationship among the process-structure-performance was clarified.This research not only opens a new technical path for the preparation of high-performance pure PLA but also provides important guidance for the high-performance modification of other semi-crystalline polymers,thus possessing significant scientific and engineering value.展开更多
Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA s...Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA still poses potential environmental pollution risks after being discarded.The efficient chemical recycling of PLA represents an attractive approach to addressing both resource reuse and environmental pollution challenges caused by its waste.Hydrolysis is the predominant method of industrial recycling.However,because PLA is insoluble in water,efficient heterogeneous hydrolysis requires high-temperature and high-pressure conditions.In this study,an efficient homogenous hydrolysis method capable of simultaneously dissolving PLA and calcium hydroxide(Ca(OH)_(2))was developed.Suitable solvents for this method were screened,and it was found that PLA hydrolysis using dioxane and 1,4,7,10,13-Pen-taoxacyclopentadecane as solvents achieved conversion rates of 93%and 90%,respectively,within 2 h at room temperature.Notably,the hydrolysis product,calcium lactate,precipitated as a solid from the solvent and therefore self-separated from the reaction solution.The solvent,acid/base conditions,water content,and depolymerization kinetics were investigated.Compared with previously reported hydrolysis methods,the enhanced efficiency observed in this study can be attributed to the concurrent solvation of PLA and Ca(OH)_(2),which maintains homogeneity throughout the reaction process.Additionally,this method facilitates closed-loop recycling of PLA and is compatible with the highly selective recovery of PLA from various types of PLA products.展开更多
Lactic acid bacteria(LAB)exopolysaccharides(EPS)reveal high safety and multiple activities,and are typical postbiotics produced by LAB during fermentation.In this paper,6583 articles on LAB-EPS from Web of Science and...Lactic acid bacteria(LAB)exopolysaccharides(EPS)reveal high safety and multiple activities,and are typical postbiotics produced by LAB during fermentation.In this paper,6583 articles on LAB-EPS from Web of Science and Elsevier databases were retrieved,and 236 articles related to this review were screened.The EPS from 90 LAB strains were summarized in terms of their extraction methods,yield,molecular weight,monosaccharide composition,glycosidic bond configuration and the structural and activity relationships(SARs).However,there exist great challenges as for the low yield and high cost in EPS production.Therefore,this review further elaborated the mechanism of EPS secretion,the anabolic pathway of EPS,the structure and mechanism of key enzymes involving in EPS synthesis process,the prospect of gene regulation for EPS secretion,and proposed the engineering strategies for increasing EPS yield or tailored EPS design in recent years.In addition,CRISPR/Cas9 gene editing technology was also discussed in the production control of EPS in LAB.Finally,the engineering strategy of increasing EPS yield in recent years was proposed.This work might provide important theoretical support for the production and application of LAB-based EPS.展开更多
BACKGROUND The central link between septic shock and acute skin failure(ASF)is the inflammatory response,which occurs throughout disease progression and can lead to systemic inflammatory response syndrome.Patients oft...BACKGROUND The central link between septic shock and acute skin failure(ASF)is the inflammatory response,which occurs throughout disease progression and can lead to systemic inflammatory response syndrome.Patients often experience bad moods,sleep disorders,and other health issues.Despite recognizing these factors,no studies have examined the correlation between inflammatory factors,lactic acid levels,ASF,mood disturbances,and sleep quality in critically ill patients.We hypothesize that higher levels of inflammatory factors and lactic acid are associated with more severe ASF and poorer mood and sleep quality,which may inform clinical treatment for septic shock and ASF.AIM To explore the relationship between inflammatory factors,lactic acid levels,the severity of ASF,bad mood,and sleep quality.METHODS The retrospective study included 150 patients with septic shock from the Second Hospital of Dalian Medical University,categorized into ASF(n=35)or non-ASF groups(n=115).We compared the peripheral blood inflammatory factors,including tumor necrosis factor-α(TNF-α),C-reactive protein(CRP),interleukin-6(IL-6),lactic acid levels,skin mottling score(SMS),modified early warning score(MEWS),self-rating depression scale(SDS),self-rating anxiety scale(SAS),and Pittsburgh sleep quality index(PSQI)scores.Pearson correlation analysis assessed relationships among these variables.RESULTS The ASF group had significantly higher levels of CRP(19.60±4.10 vs 15.30±2.96 mg/mL),IL-6(298.65±48.65 vs 268.66±33.66 pg/L),procalcitonin,lactic acid(8.42±2.32 vs 5.70±1.27 mmol/L),SMS[0(0,1)vs 3(2,3)],MEWS(9.34±1.92 vs 6.48±1.96),SAS(61.63±12.03 vs 53.71±12.48),SDS(60.17±12.64 vs 52.27±12.64),and PSQI scores(14.23±3.94 vs 8.69±2.46)compared with the non-ASF group(all P<0.001).Pearson correlation analysis revealed that IL-6,CRP,TNF-α,and lactic acid were positively correlated with SMS,MEWS,SAS,SDS,and PSQI scores(P<0.05).CONCLUSION Peripheral blood levels of IL-6,CRP,TNF-α,and lactic acid correlate positively with SMS,MEWS,SAS,SDS,and PSQI in critically ill patients with ASF.展开更多
AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mes...AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mesoporous PLA.In vitro and in vivo release experiments and ocular toxicology evaluation of the formulation were performed.The antiproliferative effect of this 5-FU-PLA tablet after glaucoma filtration surgery in rabbits was evaluated.Pathology,immunohistochemistry,and Western blot were used to further validate the inhibitory effect of this sustained release system.RESULTS:Various drug formulations were tested,and two 5-FU-PLA tablets,namely 1.5P15(5-FU 1.5 mg+PLA 15000 Da)and 2.5P15(5-FU 2.5 mg+PLA 15000 Da),had the most suitable release profiles in vitro.Further in vivo studies confirmed the safety and sustained-release profiles of both drugs.Both 5-FU-PLA tablets,relative to the free drugs,significantly inhibited tissue proliferation after glaucoma filtration and improved surgical success.Western blot showed that transforming growth factor-β(TGF-β)and connective tissue growth factor(CTGF)were inhibited by 5-FU after filtration surgery,with the effects of the 5-FU-PLA tablets being more lasting.CONCLUSION:The tested 5-FU-PLA tablets provide a sustained release of 5-FU,which may be used for a single subconjunctival implantation to inhibit proliferation after filtration surgery.展开更多
The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved ...The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved to incorporate smart materials capable of responding to various stimuli.This study explores the potential of thermoresponsive sutures,made from shape memory materials,that contract upon heating to bring loose stitches closer together,promoting optimal wound closure.We developed nanocomposites based on a blend of poly(lactic acid)(PLA)and thermoplastic polyurethane(TPU)—biopolymers that inherently exhibit shape memory—enhanced with carbon nanotubes(CNT)and graphene nanoplatelets(GN)to improve mechanical performance.PLA/TPU(50/50)nanocomposites were prepared with 1 and 2 wt%GN,as well as hybrid formulations combining 1 wt%CNT with 1 or 2 wt%GN,using a twin-screw extrusion process to form filaments.These filaments were characterized through differential scanning calorimetry(DSC),field emission gun scanning electron microscopy(FEG-SEM),tensile testing,and shape memory assessments.While the PLA/TPU blend is immiscible,TPU enhances the crystallinity(X_(c))of the PLA phase,further increased by the addition of CNT and GN.FEG-SEM images indicate CNTs primarily in the PLA phase and GN in the TPU phase.PLA/TPU with 1 or 2 wt%GN showed the highest potential for suture applications,with a high elastic modulus(~1000 MPa),significant strain at break(~10%),and effective shape recovery(~20%at 55℃ for 30 min).These findings suggest that these nanocomposites can enhance suture performance with controlled shape recovery that is suitable for medical use.展开更多
Pt/activated carbon （Pt/AC） catalyst combined with base works efficiently for lactic acid production from glycerol under mild conditions. Base type （LiOH, NaOH, KOH, or Ba（OH）2） and base/glycerol molar ratio sig...Pt/activated carbon （Pt/AC） catalyst combined with base works efficiently for lactic acid production from glycerol under mild conditions. Base type （LiOH, NaOH, KOH, or Ba（OH）2） and base/glycerol molar ratio significantly affected the catalytic performance. The corresponding lactic acid selectivity was in the order of LiOH〉NaOH〉KOH〉Ba（OH）2. An increase in LiOH/glycerol molar ratio ele‐vated the glycerol conversion and lactic acid selectivity to some degree, but excess LiOH inhibited the transformation of glycerol to lactic acid. In the presence of Pt/AC catalyst, the maximum selec‐tivity of lactic acid was 69.3% at a glycerol conversion of 100% after 6 h at 90 °C, with a Li‐OH/glycerol molar ratio of 1.5. The Pt/AC catalyst was recycled five times and was found to exhibit slightly decreased glycerol conversion and stable lactic acid selectivity. In addition, the experimental results indicated that reaction intermediate dihydroxyacetone was more favorable as the starting reagent for lactic acid formation than glyceraldehyde. However, the Pt/AC catalyst had adverse effects on the intermediate transformation to lactic acid, because it favored the catalytic oxidation of them to glyceric acid.展开更多
[Objective] The aim was to conduct preliminary investigation and diversity analysis of lactic acid bacteria resources in forage from Turpan of Xinjiang. [Method] The lactic acid bacteria in the three kinds of forage i...[Objective] The aim was to conduct preliminary investigation and diversity analysis of lactic acid bacteria resources in forage from Turpan of Xinjiang. [Method] The lactic acid bacteria in the three kinds of forage ingredients in Xinjiang were isolated by using plate separation method and screened by MRS＋CaCO3 solid medium. Morphological, physiological and biochemical identification and 16S rDNA gene sequence analysis were carried out to the isolated eighty strains of lactic acid bacteria, to explore its taxonomic status. [Result] Twenty strains of lactic acid bacteria were obtained from alfalfa, forty-one from wheat, and nineteen from corn. The physiological and biochemical identification and 16S rDNA gene sequence analysis results showed that the eighty strains of lactic acid bacteria belonged to two genera, namely, Lactobacillus, Enterococcus; 7 species, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei, Entercoccus faecium, Entercoccus durans, Lactobacillus plantarum, Entercoccus hirae. Lactobacillus casei and Entercoccus faecium were ubiquitous in the three kinds of forage ingredients. Besides these two lactic acid bacteria, there were Lactobacillus rhamnosus, Lactobacillus paracasei, Lactobacillus plantarum in wheat, Lactobacillus plantarum, Lactobacillus paracasei, Entercoccus hirae, Entercoccus durans in alfalfa, Lactobacillus plantarum, Entercoccus durans in corn. [Conclusion] There is a big diversity of lactic acid bacteria in different forage from Turpan of Xinjiang, in which Lactobacillus casei, Entercoccus faecium are the key bacteria for forage fermentation.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
Two lactic acid bacteria strains (At1BEAE22 and At344E21) isolated during tchapalo production were identified on the basis of phenotypic analyses. Bacteriocins produced by these strains were tested for their antimicro...Two lactic acid bacteria strains (At1BEAE22 and At344E21) isolated during tchapalo production were identified on the basis of phenotypic analyses. Bacteriocins produced by these strains were tested for their antimicrobial activities using well diffusion agar method. Heat resistance, pH sensitivity and enzyme treatments were also analyzed. Results showed that both lactic acid bacteria strains were identified as Pediococcus acidilactici. Their bacteriocins inhibited growth of Lactobacillus delbrueckii F/31, Listeria innocua ATCC 33090, Enterococcus faecalis, Enterococcus faecalis ATCC 29212, Streptococcus sp, Enterococcus faecalis CIP 105042 and Enterococcus faecium ATCC 51558. These bacteriocins were heat stable at 60°C for 30 min for all indicator bacteria. However, they remained active only against Lactobacillus delbrueckii and Listeria innocua at 121°C for 60 min. Moreover, they were active in a wide range of pH (3 to 9) with a maximum activity observed at pH 5 and 6 on all indicator bacteria. But, bacteriocin from Pediococcus acidilactici At34E21 was more stable at acidic pH than basic one. The fact that the bacteriocin was inactivated by proteinase K and α-chymotrypsin indicated its proteinaceous nature, a general characteristics of bacteriocins.展开更多
Indigenous fermented foods are known for their nutritional and functional properties but they are often spoiled by pathogenic bacteria that can constitute a food safety problem. “Gappal” is a no-thermal treat food b...Indigenous fermented foods are known for their nutritional and functional properties but they are often spoiled by pathogenic bacteria that can constitute a food safety problem. “Gappal” is a no-thermal treat food based on millet dough and milk and its production conditions can constitute a food safety problem. The aim of this study was to screen and identify LAB producing Bacteriocin-like inhibitory substances using a matrix similar to “Gappal”. The detection of potential BLIS was first performed using overlaid method after enrichment of samples in whey and millet dough. The isolates demonstrating inhibiting area were preselected, purified and tested for the presence of antibacterial properties using their neutralized cell-free culture supernatant and subsequently treated with catalase in combination with protease, pepsin or trypsin. The antimicrobial effect of two isolates (Gbf48 and Gbf50) after growth on MRS broth over 12 h at 30?C were active against E. faecalis ATCC 19433, M. luteus ATCC 49732, S. aureus ATCC 2523, L. monocytogenes, B. megaterium, B. sphaericus and B. cereus with an activity of 2560 AU/mL. The 16S RNA gene sequencing identification indicated that these isolates are Pediococcus acidilactici. Gbf 48 and Gbf 50 could be used to improve preservative factors for a controlled fermentation of non thermal treatment fermented food for their potential of acidification adds to BLIS production.展开更多
Various ZSM-5 zeolites modified with alkali metals （Li, Na, K, Rb, and Cs） were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid （LA） to acrylic acid （AA）....Various ZSM-5 zeolites modified with alkali metals （Li, Na, K, Rb, and Cs） were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid （LA） to acrylic acid （AA）. The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, tempera- ture-programmed desorptions of NH3 and CO2, pyridine adsorption spectroscopy, and N2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities （LHSVs） to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions （40 wt% LA aqueous solution, 365 ℃, and LHSV 2 h-1）.展开更多
文摘Developing efficient photocatalysts to address collaborative energy and environmental crises still faces significant challenges.In this report,we present a highly efficient MXene–based photocatalyst,which is combined with MoS_(2)nano patches and TiO_(2)/Ti_(3)C_(2)(TTC)nanowires through hydrothermal treatment.Of all the composites tested,the optimized photocatalyst gave a remarkable H_(2)and revolving polylactic acid(PLA)into pyruvic acid(PA).Achieving a remarkable H_(2)evolution rate of 637.1 and 243.2μmol g^(−1)h^(−1),in the presence of TEOA and PLA as a sacrificial reagent under UV-vis(λ≥365 nm)light irradiation.The improved photocatalytic activity is a result of the combination of dual cocatalyst on the surface of TTC photocatalyst,which create an ideal synergistic effect for the generation of PA and the production of H_(2)simultaneously.The MoS_(2)TiO_(2)/Ti_(3)C_(2)(MTT)composite can generate more photoexcited charge carriers,leading to the generation of more active radicals,which may enhance the system's photocatalytic activity.This work aims at demonstrating its future significance and guide the scientific community towards a more efficient approach to commercializing H_(2)through photocatalysis.
基金supported by the National Natural Science Foundation of China(Nos.31971741 and 31760195)the Yunnan Fundamental Research Projects(Nos.2018FB066 and 202001AT070141)the Yunnan Agricultural Basic Research Special Projects(No.202101BD070001-086).
文摘The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.
基金supported by the Innovation Talents Project of Harbin Science and Technology Bureau(2022CXRCCGO11)。
文摘This study examined the effects of pasteurization(PAS),ultrasonic sterilization(ULS),and microwave sterilization(MWS)on the quality and storage characteristics of brine-fermented tofu(BFT)and fermented tofu(FT).Comparative analysis revealed that MWS had a negligible detrimental effect on the structural integrity and organoleptic properties of BFT and FT,while effectively maintaining its water-holding capacity(WHC)and exhibiting the least impact on its texture.In contrast,PAS and ULS increased hardness and chewiness significantly(P<0.05),but ULS also enhanced the brightness of tofu.Throughout the storage period,the WHC,elasticity,and sensory properties of tofu generally decreased,whereas the hardness and chewiness increased.PAS-BFT and MWS-FT maintained sensory quality for the longest periods of 14 and 12 days respectively,and could be decomposed to more small molecule peptides within 0–8 days and 0–6 days,which are more easily to be absorbed by the body.The findings discovered that MWS is the most suitable method for sterilization of tofu,with superior capability in maintaining the quality,extending shelf life,and improving digestibility of tofu.
基金supported by the National Natural Science Foundation of China(Nos.22368014 and 22478087)Guizhou Provincial S&T Project(Nos.GCC[2023]011 and ZK[2022]011).
文摘Photocatalytic selective synthesis of lactic acid(LA)from biomass sugars with a single heterogeneous catalyst is promising but challenging due to the multiple reaction steps involved.Herein,a K-doped C-rich red polymerized carbon nitride(RPCN)photocatalyst with uniform K/C dual sites was constructed by a molten salt template method,which was highly efficient for cascade isomerization dehydration of glucose to LA with>90%selectivity under visible light and gentle conditions.Control experiments and theoretical calculations expounded that the introduced K/C dual sites could improve the light capture ability and photogenerated charge separation efficiency,while the K species provided sufficient Lewis acid sites(adsorption sites)for the isomerization of glucose to fructose.Meanwhile,the introduced C sites that substitute N atoms could promote electrons to be captured by adsorbed oxygen for selective generation of superoxide radicals,which was highly efficient for the scission of the C3-C4 bond in fructose,exclusively furnishing LA.Importantly,the RPCN photocatalyst was also suitable for the photocatalytic upgrading of various biomass saccharides into LA with high yields of 81.3%-95.3%and could be recycled for five consecutive cycles.The tailored construction of dual sites by localization of space charge lightens an avenue for multi-step conversion of biomass with pronounced selectivity.
基金the Natural Science Foundation of China(22368014,22478087)the Guizhou Provincial S&T Project(GCC[2023]011,ZK[2022]011).
文摘Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and utilization of near-infrared light,accounting for 50%of sunlight.Here,a molten salt-assisted in-plane“stitching”and interlayer“cutting”protocol is developed for constructing a highly crystalline carbon nitride catalyst containing structural oxygen(HC-CN).HC-CN is highly efficient for the photothermal cascade transformation of biomass-derived glucose into lactic acid(LA)with an unprecedented yield(94.3%)at 25°C under full-spectrum light irradiation within 50 min,which is also applicable to quantitatively photo-upgrading various saccharides.Theoretical calculations expound that the light-induced glucose-to-catalyst charge transfer can activate the Cβ-H bond to promote the rate-determining step of intramolecular hydrogen shift in glucose-to-fructose isomerization.Meanwhile,the introduced structural oxygen in HC-CN can not only facilitate the local electric field formation to achieve rapid charge transport/separation and regulate selective·O^(-)_(2)generation for oriented C3-C4 bond cleavage of fructose but also narrow the energy band gap to broaden the light absorption range of HC-CN,contributing to enhanced LA production without exogenous heating.Moreover,HC-CN is highly recyclable and exhibits negligible environmental burden and low energy consumption,as disclosed by the life cycle assessment.Tailored construction of full-spectrum light adsorption and versatile reaction sites provides a reference for implementing multi-step biomass and organic conversion processes under mild conditions.
基金Funded by the National Natural Science Foundation of China(No.21104031)the Education Department of Hunan province in 2020(No.20C1589)。
文摘This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By means of an organic synthesis technique,epoxidized soybean oil(ESO)is chemically grafted to PLA to synthesize ESO chemically plastically modified PLA,abbreviated ECP.To fabricate PLA/ECP/n-MgO composite materials,ECP acts as a plasticizer and a compatibilizer simultaneously,and n-MgO acts as an enhancer.Then scanning electron microscopy,X-ray diffraction,differential scanning calorimetry,universal tester,and antibacterial research were exploited to characterize the morphology,thermal resistance,mechanical properties,and antibacterial performance of PLA/ECP/n-MgO composites.The experimental results show that ECP acts as a plasticizer by causing heterogeneous nucleation,which increases PLA's crystallinity.Evenly distributed n-MgO can greatly improve PLA's antibacterial qualities.Furthermore,ECP and n-MgO work together to improve the positive aspects of PLA/ECP/n-MgO composites,with PLA/ECP/n-MgO 100/1/0.5 composites having the best overall properties.While improving the mechanical performance and toughness of PLA,this work offers a prospective approach and foundational database for the creation of multifunctional biodegradable composites.
基金funded by National Natural Science Foundation of China(32360564)the Natural Science and Technology Innovation Development Multiplication Plan of Guangxi University(2022BZRC010)。
文摘Hyperuricemia(HUA)is characterized by elevated levels of uric acid(UA)in the bloodstream,resulting from either excessive production or insufficient excretion of UA within the body.If left untreated,progressive or persistent HUA can lead to gout,causing significant harm to human health.Lactic acid bacteria(LAB),generally recognized as safe(GRAS)probiotics,have been shown to alleviate symptoms associated with gastrointestinal disorders such as irritable bowel syndrome and inflammatory bowel disease while supporting overall bodily functions and health.Recently,LAB has emerged as a potentially safe,cost-effective and efficient treatment for HUA.This comprehensive review aims to explore the current literature on the mechanisms through which LAB controls HUA.These mechanisms include suppressing purine metabolism,absorbing purine compounds,modulating microbiota to maintain host global purine homeostasis,reducing intestinal permeability,producing metabolites that alleviate HUA symptoms,promoting the expression of urate excretory proteins and inhibiting the expression of urate reabsorption proteins.The findings presented in this review provide a framework for further investigation into how probiotic LAB can alleviate HUA by influencing UA metabolism and elucidating their underlying action mechanisms.
基金supported by the National Key Research and Development Program of China(No.2023YFC3904604)the Fundamental Research Funds for the Central Universities(No.2024ZYGXZR080)+1 种基金Science and Technology Project of Guangzhou(No.2025A04J3914)Research and Development Program of Jiangmen(No.2023780200030009506).
文摘To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)process that can produce pure PLA with excellent mechanical properties.The MDP process generates a dynamic stretching effect by regulating the application and release of pressure,prompting disordered molecular chains to be arranged regularly along the direction of the dynamic force field.This promoted the formation of more ordered crystal forms(α-form)and strengthened the connection between the crystalline and amorphous regions.Results show that after MDP treatment,the tensile strength and strain at break of MDP-PLA are significantly improved,reaching 91.6 MPa and 80.1%respectively,which are 49.4%higher and 10 times higher than those of the samples before treatment.The mechanical properties of MDP-PLA can be regulated as needed by adjusting the cycle times and peak pressure.In addition,through a systematic study of the structural evolution of MDP-PLA,the performance regulation mechanism of the MDP process was thoroughly investigated,and the internal relationship among the process-structure-performance was clarified.This research not only opens a new technical path for the preparation of high-performance pure PLA but also provides important guidance for the high-performance modification of other semi-crystalline polymers,thus possessing significant scientific and engineering value.
基金financially supported by the National Key R&D Program of China(No.2021YFB3801901)the National Natural Science Foundation of China(No.22075188 and U19A2095)supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology。
文摘Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA still poses potential environmental pollution risks after being discarded.The efficient chemical recycling of PLA represents an attractive approach to addressing both resource reuse and environmental pollution challenges caused by its waste.Hydrolysis is the predominant method of industrial recycling.However,because PLA is insoluble in water,efficient heterogeneous hydrolysis requires high-temperature and high-pressure conditions.In this study,an efficient homogenous hydrolysis method capable of simultaneously dissolving PLA and calcium hydroxide(Ca(OH)_(2))was developed.Suitable solvents for this method were screened,and it was found that PLA hydrolysis using dioxane and 1,4,7,10,13-Pen-taoxacyclopentadecane as solvents achieved conversion rates of 93%and 90%,respectively,within 2 h at room temperature.Notably,the hydrolysis product,calcium lactate,precipitated as a solid from the solvent and therefore self-separated from the reaction solution.The solvent,acid/base conditions,water content,and depolymerization kinetics were investigated.Compared with previously reported hydrolysis methods,the enhanced efficiency observed in this study can be attributed to the concurrent solvation of PLA and Ca(OH)_(2),which maintains homogeneity throughout the reaction process.Additionally,this method facilitates closed-loop recycling of PLA and is compatible with the highly selective recovery of PLA from various types of PLA products.
基金supported by the Natural Science Foundation of Heilongjiang Province(LH2021C075)Basic Research Business Expenses and Research Projects of Provincial Higher Education Institutions in Heilongjiang Province(2022-KYYWF-1077).
文摘Lactic acid bacteria(LAB)exopolysaccharides(EPS)reveal high safety and multiple activities,and are typical postbiotics produced by LAB during fermentation.In this paper,6583 articles on LAB-EPS from Web of Science and Elsevier databases were retrieved,and 236 articles related to this review were screened.The EPS from 90 LAB strains were summarized in terms of their extraction methods,yield,molecular weight,monosaccharide composition,glycosidic bond configuration and the structural and activity relationships(SARs).However,there exist great challenges as for the low yield and high cost in EPS production.Therefore,this review further elaborated the mechanism of EPS secretion,the anabolic pathway of EPS,the structure and mechanism of key enzymes involving in EPS synthesis process,the prospect of gene regulation for EPS secretion,and proposed the engineering strategies for increasing EPS yield or tailored EPS design in recent years.In addition,CRISPR/Cas9 gene editing technology was also discussed in the production control of EPS in LAB.Finally,the engineering strategy of increasing EPS yield in recent years was proposed.This work might provide important theoretical support for the production and application of LAB-based EPS.
文摘BACKGROUND The central link between septic shock and acute skin failure(ASF)is the inflammatory response,which occurs throughout disease progression and can lead to systemic inflammatory response syndrome.Patients often experience bad moods,sleep disorders,and other health issues.Despite recognizing these factors,no studies have examined the correlation between inflammatory factors,lactic acid levels,ASF,mood disturbances,and sleep quality in critically ill patients.We hypothesize that higher levels of inflammatory factors and lactic acid are associated with more severe ASF and poorer mood and sleep quality,which may inform clinical treatment for septic shock and ASF.AIM To explore the relationship between inflammatory factors,lactic acid levels,the severity of ASF,bad mood,and sleep quality.METHODS The retrospective study included 150 patients with septic shock from the Second Hospital of Dalian Medical University,categorized into ASF(n=35)or non-ASF groups(n=115).We compared the peripheral blood inflammatory factors,including tumor necrosis factor-α(TNF-α),C-reactive protein(CRP),interleukin-6(IL-6),lactic acid levels,skin mottling score(SMS),modified early warning score(MEWS),self-rating depression scale(SDS),self-rating anxiety scale(SAS),and Pittsburgh sleep quality index(PSQI)scores.Pearson correlation analysis assessed relationships among these variables.RESULTS The ASF group had significantly higher levels of CRP(19.60±4.10 vs 15.30±2.96 mg/mL),IL-6(298.65±48.65 vs 268.66±33.66 pg/L),procalcitonin,lactic acid(8.42±2.32 vs 5.70±1.27 mmol/L),SMS[0(0,1)vs 3(2,3)],MEWS(9.34±1.92 vs 6.48±1.96),SAS(61.63±12.03 vs 53.71±12.48),SDS(60.17±12.64 vs 52.27±12.64),and PSQI scores(14.23±3.94 vs 8.69±2.46)compared with the non-ASF group(all P<0.001).Pearson correlation analysis revealed that IL-6,CRP,TNF-α,and lactic acid were positively correlated with SMS,MEWS,SAS,SDS,and PSQI scores(P<0.05).CONCLUSION Peripheral blood levels of IL-6,CRP,TNF-α,and lactic acid correlate positively with SMS,MEWS,SAS,SDS,and PSQI in critically ill patients with ASF.
基金Supported by the National Natural Science Foundation of China(No.82301211)Beijing Natural Science Foundation(No.J230028).
文摘AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mesoporous PLA.In vitro and in vivo release experiments and ocular toxicology evaluation of the formulation were performed.The antiproliferative effect of this 5-FU-PLA tablet after glaucoma filtration surgery in rabbits was evaluated.Pathology,immunohistochemistry,and Western blot were used to further validate the inhibitory effect of this sustained release system.RESULTS:Various drug formulations were tested,and two 5-FU-PLA tablets,namely 1.5P15(5-FU 1.5 mg+PLA 15000 Da)and 2.5P15(5-FU 2.5 mg+PLA 15000 Da),had the most suitable release profiles in vitro.Further in vivo studies confirmed the safety and sustained-release profiles of both drugs.Both 5-FU-PLA tablets,relative to the free drugs,significantly inhibited tissue proliferation after glaucoma filtration and improved surgical success.Western blot showed that transforming growth factor-β(TGF-β)and connective tissue growth factor(CTGF)were inhibited by 5-FU after filtration surgery,with the effects of the 5-FU-PLA tablets being more lasting.CONCLUSION:The tested 5-FU-PLA tablets provide a sustained release of 5-FU,which may be used for a single subconjunctival implantation to inhibit proliferation after filtration surgery.
基金This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoalde Nível Superior-Brasil(CAPES)-Finance Code 001.
文摘The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved to incorporate smart materials capable of responding to various stimuli.This study explores the potential of thermoresponsive sutures,made from shape memory materials,that contract upon heating to bring loose stitches closer together,promoting optimal wound closure.We developed nanocomposites based on a blend of poly(lactic acid)(PLA)and thermoplastic polyurethane(TPU)—biopolymers that inherently exhibit shape memory—enhanced with carbon nanotubes(CNT)and graphene nanoplatelets(GN)to improve mechanical performance.PLA/TPU(50/50)nanocomposites were prepared with 1 and 2 wt%GN,as well as hybrid formulations combining 1 wt%CNT with 1 or 2 wt%GN,using a twin-screw extrusion process to form filaments.These filaments were characterized through differential scanning calorimetry(DSC),field emission gun scanning electron microscopy(FEG-SEM),tensile testing,and shape memory assessments.While the PLA/TPU blend is immiscible,TPU enhances the crystallinity(X_(c))of the PLA phase,further increased by the addition of CNT and GN.FEG-SEM images indicate CNTs primarily in the PLA phase and GN in the TPU phase.PLA/TPU with 1 or 2 wt%GN showed the highest potential for suture applications,with a high elastic modulus(~1000 MPa),significant strain at break(~10%),and effective shape recovery(~20%at 55℃ for 30 min).These findings suggest that these nanocomposites can enhance suture performance with controlled shape recovery that is suitable for medical use.
基金supported by the National Natural Science Foundation of China(21176236)~~
文摘Pt/activated carbon （Pt/AC） catalyst combined with base works efficiently for lactic acid production from glycerol under mild conditions. Base type （LiOH, NaOH, KOH, or Ba（OH）2） and base/glycerol molar ratio significantly affected the catalytic performance. The corresponding lactic acid selectivity was in the order of LiOH〉NaOH〉KOH〉Ba（OH）2. An increase in LiOH/glycerol molar ratio ele‐vated the glycerol conversion and lactic acid selectivity to some degree, but excess LiOH inhibited the transformation of glycerol to lactic acid. In the presence of Pt/AC catalyst, the maximum selec‐tivity of lactic acid was 69.3% at a glycerol conversion of 100% after 6 h at 90 °C, with a Li‐OH/glycerol molar ratio of 1.5. The Pt/AC catalyst was recycled five times and was found to exhibit slightly decreased glycerol conversion and stable lactic acid selectivity. In addition, the experimental results indicated that reaction intermediate dihydroxyacetone was more favorable as the starting reagent for lactic acid formation than glyceraldehyde. However, the Pt/AC catalyst had adverse effects on the intermediate transformation to lactic acid, because it favored the catalytic oxidation of them to glyceric acid.
基金Supported by the Natural Science Foundation of Xinjiang University(070378)the Open Project Funding by the State Key Laboratory of Microbial Technology in Shandong University(M2011-07)~~
文摘[Objective] The aim was to conduct preliminary investigation and diversity analysis of lactic acid bacteria resources in forage from Turpan of Xinjiang. [Method] The lactic acid bacteria in the three kinds of forage ingredients in Xinjiang were isolated by using plate separation method and screened by MRS＋CaCO3 solid medium. Morphological, physiological and biochemical identification and 16S rDNA gene sequence analysis were carried out to the isolated eighty strains of lactic acid bacteria, to explore its taxonomic status. [Result] Twenty strains of lactic acid bacteria were obtained from alfalfa, forty-one from wheat, and nineteen from corn. The physiological and biochemical identification and 16S rDNA gene sequence analysis results showed that the eighty strains of lactic acid bacteria belonged to two genera, namely, Lactobacillus, Enterococcus; 7 species, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei, Entercoccus faecium, Entercoccus durans, Lactobacillus plantarum, Entercoccus hirae. Lactobacillus casei and Entercoccus faecium were ubiquitous in the three kinds of forage ingredients. Besides these two lactic acid bacteria, there were Lactobacillus rhamnosus, Lactobacillus paracasei, Lactobacillus plantarum in wheat, Lactobacillus plantarum, Lactobacillus paracasei, Entercoccus hirae, Entercoccus durans in alfalfa, Lactobacillus plantarum, Entercoccus durans in corn. [Conclusion] There is a big diversity of lactic acid bacteria in different forage from Turpan of Xinjiang, in which Lactobacillus casei, Entercoccus faecium are the key bacteria for forage fermentation.
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Two lactic acid bacteria strains (At1BEAE22 and At344E21) isolated during tchapalo production were identified on the basis of phenotypic analyses. Bacteriocins produced by these strains were tested for their antimicrobial activities using well diffusion agar method. Heat resistance, pH sensitivity and enzyme treatments were also analyzed. Results showed that both lactic acid bacteria strains were identified as Pediococcus acidilactici. Their bacteriocins inhibited growth of Lactobacillus delbrueckii F/31, Listeria innocua ATCC 33090, Enterococcus faecalis, Enterococcus faecalis ATCC 29212, Streptococcus sp, Enterococcus faecalis CIP 105042 and Enterococcus faecium ATCC 51558. These bacteriocins were heat stable at 60°C for 30 min for all indicator bacteria. However, they remained active only against Lactobacillus delbrueckii and Listeria innocua at 121°C for 60 min. Moreover, they were active in a wide range of pH (3 to 9) with a maximum activity observed at pH 5 and 6 on all indicator bacteria. But, bacteriocin from Pediococcus acidilactici At34E21 was more stable at acidic pH than basic one. The fact that the bacteriocin was inactivated by proteinase K and α-chymotrypsin indicated its proteinaceous nature, a general characteristics of bacteriocins.
文摘Indigenous fermented foods are known for their nutritional and functional properties but they are often spoiled by pathogenic bacteria that can constitute a food safety problem. “Gappal” is a no-thermal treat food based on millet dough and milk and its production conditions can constitute a food safety problem. The aim of this study was to screen and identify LAB producing Bacteriocin-like inhibitory substances using a matrix similar to “Gappal”. The detection of potential BLIS was first performed using overlaid method after enrichment of samples in whey and millet dough. The isolates demonstrating inhibiting area were preselected, purified and tested for the presence of antibacterial properties using their neutralized cell-free culture supernatant and subsequently treated with catalase in combination with protease, pepsin or trypsin. The antimicrobial effect of two isolates (Gbf48 and Gbf50) after growth on MRS broth over 12 h at 30?C were active against E. faecalis ATCC 19433, M. luteus ATCC 49732, S. aureus ATCC 2523, L. monocytogenes, B. megaterium, B. sphaericus and B. cereus with an activity of 2560 AU/mL. The 16S RNA gene sequencing identification indicated that these isolates are Pediococcus acidilactici. Gbf 48 and Gbf 50 could be used to improve preservative factors for a controlled fermentation of non thermal treatment fermented food for their potential of acidification adds to BLIS production.
文摘Various ZSM-5 zeolites modified with alkali metals （Li, Na, K, Rb, and Cs） were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid （LA） to acrylic acid （AA）. The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, tempera- ture-programmed desorptions of NH3 and CO2, pyridine adsorption spectroscopy, and N2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities （LHSVs） to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions （40 wt% LA aqueous solution, 365 ℃, and LHSV 2 h-1）.
