D-Pantoic acid is an essential precursor for the synthesis of vitamin B5. However, the microbial synthesis of D-pantoic acid suffers from a low yield. Herein, to improve D-pantoic acid biosynthesis in Escherichia coli...
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D-Pantoic acid is an essential precursor for the synthesis of vitamin B5. However, the microbial synthesis of D-pantoic acid suffers from a low yield. Herein, to improve D-pantoic acid biosynthesis in Escherichia coli, the central metabolic and byproduct-forming pathways were first engineered, increasing the D-pantoic acid titer to 1.55 g/L from 0.75 g/L. Subsequently, the modification was focused on preventing the accumulation of alpha-ketoglutarate (alpha-KG). Six genes (ppc, mdh, icd, sucA, kgtP, and dcuA) related to alpha-KG metabolism and transport were screened by the CRISPRi system and further genetically manipulated. Ultimately, significantly improved D-pantoic acid biosynthesis (2.03 g/L in a shake flask and 14.78 g/L in a 5-L bioreactor) with dramatically reduced formation of byproducts was achieved. To our best knowledge, this is the first attempt to modify the key metabolic targets related to alpha-KG accumulation for enhanced D-pantoic acid biosynthesis. These findings would also offer valuable insights into the metabolic regulation of other related metabolites.
In prevailing p-i-n perovskite solar cells(PSCs),solution-processible fullerene molecules are widely used as electron-transporting layers(ETLs)but they typically suffer from poor uniformity and undesirable stability *...
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In prevailing p-i-n perovskite solar cells(PSCs),solution-processible fullerene molecules are widely used as electron-transporting layers(ETLs)but they typically suffer from poor uniformity and undesirable stability ***,a separate bathocuproine(BCP)layer is needed to block hole tran sfer,increasing fabrication complexity and ***,we address these limitations by develo ping a novel polymeric ETL(named PF BCP)synthesized by polymerizing C_(60)with *** innovative material achieves both efficient electron transport and hole blocking,while its excellent uniformity minimizes interface recombination and enhances ***,our blade-coated PSCs utilizing PFBCP achieve a high power conversion efficiency exceeding 22%and retain 91%of initial efficiency after 1200 h of light *** development not only paves the way for commercially viable PSCs but also opens avenues for future ETL design to realize even more efficient and stable PSCs.
In recent years, coxsackievirus A6 (CVA6) has surpassed enterovirus A71 to become the main pathogen causing severe Hand, Foot, and Mouth disease (HFMD) in china with a substantial disease burden. However, there is cur...
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In recent years, coxsackievirus A6 (CVA6) has surpassed enterovirus A71 to become the main pathogen causing severe Hand, Foot, and Mouth disease (HFMD) in china with a substantial disease burden. However, there is currently no commercial CVA6 vaccine. The D3a genotype of CVA6 is the predominant genotype in china. In this study, virus-like particles (VLPs) and mRNA vaccines based on the CVA6 sub-genotype D3a were successfully developed. The immunogenicity and protective effects of the VLP of CVA6 combined with Al(OH)3 and CpG adjuvant indicated that VLP-induced neutralizing antibodies against three CVA6 sub-genotype (D2, D3a, and D3b) strains in Institute of Cancer research (ICR) mice, and the combination of the two adjuvants enhanced cellular immunity. Passive immunization with serum from mice immunized with VLPs protected suckling mice against CVA6 lethal challenge in both antiserum transfer and maternal immunization experiments. The immunogenicity and protective effects of the mRNA vaccine of CVA6 indicate that it induces robust T-cell immunity. T-cell immunity was found to cross-protect against coxsackievirus A10 infection in mice. This is the first trial of a CVA6 mRNA vaccine worldwide and the first comparison of the immunogenicity and protective effects of VLP and mRNA vaccines based on D3a CVA6. The study provides a theoretical basis for the development of enteroviruses vaccines and the formulation of immunization strategies.
Accurate and sensitive detection of small molecule biomarkers, such as ascorbic acid (AA), is pivotal for clinical diagnosis of various diseases. Herein, we report the development of an integrated electrochemical sens...
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Accurate and sensitive detection of small molecule biomarkers, such as ascorbic acid (AA), is pivotal for clinical diagnosis of various diseases. Herein, we report the development of an integrated electrochemical sensor that specifically targets and analyzes the ultra-low concentration of AA. The sensor incorporates a combination of techniques, featuring a CO2 laser-engraved graphene (LEG) electrode that has been further enhanced through the application of molecularly imprinted poly-o-phenylenediamine (PPD). The laser-engraved approach yields a three-dimensional (3D) porous graphene network with large surface area and good conductivity, enabling sensitive detection of AA. Furthermore, the molecularly imprinted PPD layer provides a tailored recognition site for AA, enhancing the sensor's specificity towards the target molecule. The integrated PPD/LEG electrode demonstrates the capability to detect AA in the concentration range of 1 to 100 mu M and 10 to 100 nM, with a limit of detection (LOD) of 1.45 nM and a limit of quantification (LOQ) of 20.44 nM. The real urine sample detection indicates that the developed PPD/LEG electrode can effectively differentiate cases in the melanoma mouse model from the healthy control group. The combination of the LEG electrode with the molecularly imprinted polymer (MIP) technique presents a novel platform for integrated sensing systems, offering unprecedented accuracy and sensitivity in the detection of small molecule biomarkers at trace concentrations. This innovation offers the potential for early clinical detection of diseases, where timely and precise measurements of biomarkers are crucial for diagnosis and treatment.
The damping performance of Fe_(83)Ga_(17) alloys has been investigated in the static magnetic field (H). The results demonstrate that the damping peak value can be adjusted between 0.020 and 0.085 under the magnetic f...
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The damping performance of Fe_(83)Ga_(17) alloys has been investigated in the static magnetic field (H). The results demonstrate that the damping peak value can be adjusted between 0.020 and 0.085 under the magnetic field and reaches a maximum at the critical magnetic field (H_(cr)=0.2 m T). As H is less than H_(cr).
Pesticide adjuvants,as crop protection products,have been widely used to reduce drift loss and improve utilization efficiency by regulating droplet ***,the coordinated regulation mechanisms of adjuvants and nozzles on...
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Pesticide adjuvants,as crop protection products,have been widely used to reduce drift loss and improve utilization efficiency by regulating droplet ***,the coordinated regulation mechanisms of adjuvants and nozzles on droplet spectrum remain ***,we established the relationship between droplet spectrum evolution and liquid atomization by investigating the typical characteristics of droplet diameter distribution near the *** on this,the regulation mechanisms of distinctive pesticide adjuvants on droplet spectrum were clarified,and the corresponding drift reduction performances were quantitively evaluated by wind tunnel *** shows that the droplet diameter firstly shifts to the smaller due to the liquid sheet breakup and then prefers to increase caused by droplet *** the surface tension of sprayed liquid facilitates the uniform liquid breakup and increasing the viscosity inhibits the liquid deformation,which prolong the atomization process and effectively improve the droplet *** a result,the drift losses of flat-fan and hollow cone nozzles are reduced by about 50%after adding organosilicon and vegetable oil *** contrast,the air induction nozzle shows a superior anti-drift ability,regardless of distinctive *** findings provide insights into rational adjuvant design and nozzle selection in the field application.
O-Succinyl-L-homoserine (OSH) is an important C4 platform compound with broad applications. Its green and efficient production is receiving increasing attention. Herein, the OSH producing chassic cell was constructed ...
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O-Succinyl-L-homoserine (OSH) is an important C4 platform compound with broad applications. Its green and efficient production is receiving increasing attention. Herein, the OSH producing chassic cell was constructed by deleting the transcriptional negative regulation factor, blocking the OSH consumption pathway, and inhibiting the competitive bypass pathways. The precursor synthesis pathways of aspartic acid and homoserine were further strengthened, and the pentose phosphate pathway and glycolysis pathway were modified to enhance the NADPH supply. Adaptive evolution was applied to improve the tolerance of the cell factory to the fermentation environment. With Raman online analysis, the metabolic process model was built to guide fermentation regulation. The final titer of OSH reached 121.7 g/L with conversion of 63% in a 50 L fermenter. Based on this, a coupling production route for L-methionine and succinic acid from OSH was established with good atomic economy and environmental friendliness.
In this work, austenitic high-Mn steel that exhibits both high strength and plasticity at extremely low temperatures was designed and investigated, which demonstrates a yield strength of 1022 MPa, a tensile strength o...
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In this work, austenitic high-Mn steel that exhibits both high strength and plasticity at extremely low temperatures was designed and investigated, which demonstrates a yield strength of 1022 MPa, a tensile strength of 1532 MPa, and an elongation of 25% at 4.2 K, and enables potential operating in low-temperature structural materials. Compared to at room temperature, both the yield strength and the tensile strength of the high-Mn steel at low temperature increased, while the elongation at break decreased. A comparative study of its microstructural evolution was carried out using X-ray diffraction, transmission electron microscopy, and electron backscatter diffraction. The microstructure analysis revealed that the dislocations and nano-twinning control the strain-hardening behavior of the twinning-induced plasticity behavior of the Fe-24Mn-3.5Cr-0.4C steel.
The consistency of cooling greatly influences the quality of L-beams. In this paper, the process of cooling high-temperature L-beams by multi-jet impingement is numerically simulated. The VOF model and Realizable k-ep...
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The consistency of cooling greatly influences the quality of L-beams. In this paper, the process of cooling high-temperature L-beams by multi-jet impingement is numerically simulated. The VOF model and Realizable k-epsilon turbulence model were used, and the reliability of the Realizable k-epsilon turbulence model was verified using experiments. The jet flow rate is mainly 3-11 L/min. Numerical simulation calculations were used to obtain the distribution law of pressure, streamline, and wall shear of the flow field of the multi-nozzle jet impinging on the surface of the L-beam, as well as the distribution of Nusselt number of the L-beam and the temperature distribution at 1/2 thickness. The results suggest that the cooling uniformity of the L-beam can be enhanced by extending the cooling duration of the short edge or by concurrently increasing the water flow and time of the short edge. Based on the above strategy, a relevant industrial test program was developed. After the jet impingement cooling experiment, the L-beam's surface temperature differential decreased by 43.9 degrees C, and the bending of the L-beam was decreased by 10.4 cm. The maximum value of the magnetic field gradient associated with the stress in the L-beams was reduced by up to 80.2%.
Cold sintering as a new technology for the fabrication of ceramic composites could overcome the shortcomings of traditional high temperature sintering approach and achieve dense structure in the composite at a relativ...
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Cold sintering as a new technology for the fabrication of ceramic composites could overcome the shortcomings of traditional high temperature sintering approach and achieve dense structure in the composite at a relatively low temperature（<200℃）.In this work,a shape stabilization phase change composite is fabricated and investigated by dint of such new fabrication approach,in which a mixed nitrate salt of NaNO3-KNO3is used as phase change material and magnesia powder is acted as structure *** of deionized water as sintering additive,the effects of sintering agent content,sintering temperature,uniaxial pressure and time on the composite microstructure characteristics and macroscopic properties are *** results show that the liquid salt could be effectively accommodated in the magnesia skeleton,forming a dense and stable structure in the *** is existence of optimal cold sintering parameters at which a benign combination of mechanical strength and thermal cycling performance could be attained in the *** the sintering temperature of150℃,duration time of 8 min,uniaxial pressure of 150 MPa,and water mass content of 7%,the fabricated composite exhibits a heat storage density of 610 kJ/kg at its potential utilization temperature range of30℃-580℃ and a compressive strength over 240 MPa with a dense density higher than 98%,demonstrating that it can be a viable alternative used in thermal energy storage domains.
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