间二甲苯的离解光电离的实验与理论研究

本文利用同步辐射真空紫外和超声分子束反射式飞行时间质谱系统研究间二甲苯的光电离和离解光电离.通过测定母体离子C_(8)H_(10)^(+)和主要碎片离子(C_(8)H_(9)^(+)和C_(7)H_(7)^(+))的光电离效率谱,确定了母体分子的电离能和主要碎片离子(C_(8)H_(8)^(+)和C_(7)H_(7)^(+))的出现势分别为8.60±0.03 eV,11.76±0.04 eV和11.85±0.05 eV eV.在B3LYP/6-311++G(d,p)水平上优化了两个主要解离通道的反应物、过渡态、中间体和产物的结构,并在G3水平上计算了它们的能量,以及两个主要的离解光电离通道产物C_(7)H_(7)^(+)+CH_(3)和C_(8)H_(9)^(+)+H的能量.结合理论和实验结果,间二甲苯的离解光电离机理主要过程是C-H键或C-C键的离解和氢迁移.

Flavonoid content and radical scavenging activity in fruits of Chinese dwarf cherry(Cerasus humilis) genotypes

The Chinese dwarf cherry（Cerasus humilis（Bge.） Sok.） is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia’’ and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content（TFC）, composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to72.8 mg/g REáFW（RE： rutin equivalent, FW： fresh weight）while fruit flesh TFC ranged from 4.3 to 16.9 mg/g REáFW.An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1（PA-B1）, proanthocyanidin B2（PA-B2）, phloretin 20-O-glucoside（PG）, and phloretin 20,40-O-diglucoside（PDG）. Principal component analysis showed that PG, PA-B1, and PA-B2 had large,positive factor loading values in the first principal component for each genotype. Increased scavenging activity of2,2-diphenyl-1-picrylhydrazyl（DPPH） radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’,‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.

Biomechanical characterization of a novel ring connector for sutureless aortic anastomosis

The surgical treatment for aortic diseases remains a challenge for any cardiac surgeon. The use of sutureless ring connector in aortic anastomosis can simplify the procedure and shorten anastomosis time. Therefore, we developed a novel device for sutureless aortic anastomosis. A series of experiments were carried out for tensile and leakproofcapacity assessments to verify the feasibility of the ring connector by using fresh swine aorta samples. In in vivo test,the ring connector was implanted in 6 swine with follow-up of 6 months. Radiographic and pathological studies of the aorta were performed. In the tensile tests, the strength was 32.7±5.9 Newton(N) in the sutureless anastomosis group,compared with 73.3±12.5 N in the control group by traditional manual suture. In the leakproof-capacity assessment,no sign of either leakage or bursting was evident at 280 mmHg of internal pressure in the aorta samples. In in vivo tests,it took 9.47±0.3 minutes for the sutureless anastomosis, compared with 15.58± 1.39 minutes for hand-sewn suturing. Insertion was easy and rapid. Radiographic and pathological studies were performed at first month, third month and sixth month after surgery, each time obtained from the two swine, showed patency of the anastomosis and no signs of stenosis, blood leakage, migration or pseudoaneurysm formation, except one paralyzed swine developed of thrombo-occlusion at the site of the sutureless anastomosis. The result indicates that this novel ring connector offers considerable promise for sutureless aortic anastomosis.

Expression of HERG in musculoskeletal tumors with different degrees of malignancy

Objective The expression of HERG in common bone tumors is scarcely reported and there is a lack of dedicated studies.This study aimed to investigated the expression of HERG in several common musculoskeletal tumors.Methods Immunohistochemical staining,RT-PCR,and Western blotting were used to observe HERG expression differences in various tissues and cell lines.Results HERG was differentially expressed in different malignant tumors,both at a differential protein level and localization within tumors.HERG was not expressed in normal bone tissue.The HERG inhibitor E-4031 markedly inhibited the proliferation of osteosarcoma cell lines.Conclusion HERG was highly expressed in malignant tumors.Blocking of HERG can effectively inhibit the proliferation of bone tumors.

Divergent expression of Neurl3 from hemogenic endothelial cells to hematopoietic stem progenitor cells during development

Prior to the generation of hematopoietic stem cells(HSCs)from the hemogenic endothelial cells(HECs)mainly in the dorsal aorta in midgestational mouse embryos,multiple hematopoietic progenitors including erythro-myeloid progenitors and lymphoid progenitors are generated from yolk sac HECs.These HSCindependent hematopoietic progenitors have recently been identified as major contributors to functional blood cell production until birth.However,little is known about yolk sac HECs.Here,combining integrative analyses of multiple single-cell RNA-sequencing datasets and functional assays,we reveal that Neurl3-EGFP,in addition to marking the continuum throughout the ontogeny of HSCs from HECs,can also serve as a single enrichment marker for yolk sac HECs.Moreover,while yolk sac HECs have much weaker arterial characteristics than either arterial endothelial cells in the yolk sac or HECs within the embryo proper,the lymphoid potential of yolk sac HECs is largely confined to the arterial-biased subpopulation featured by the Unc5b expression.Interestingly,the B lymphoid potential of hematopoietic progenitors,but not for myeloid potentials,is exclusively detected in Neurl3-negative subpopulations in midgestational embryos.Taken together,these findings enhance our understanding of blood birth from yolk sac HECs and provide theoretical basis and candidate reporters for monitoring step-wise hematopoietic differentiation.

Comprehensive transcriptomic analysis of developing seed in Cerasus humilis for lipid related gene discovery

Cerasus humilis is a woody shrub with increasing economic importance. Due to its high oil content in seed with desired fatty acid(FA) composition, C. humilis has been considered as a potential woody oilseed crop in China. However, FAs accumulation and related molecular mechanisms of FA biosynthesis in C. humilis seed have not been elucidated well. In this study, oil contents and FA compositions of developing C. humilis seed were analyzed. The total oil content in mature seed reached 48.7% while unsaturated FA concentration reached a high level of 96.2%. Three c DNA libraries of C. humilis developing seed were constructed at the beginning and 2 fast oil-accumulation stages, followed by Illumina sequencing with the platform of HiSeq^TM 2000. Differentially expressed unigenes(DEGs) were identified during the respective seed development stages to investigate transcription dynamics. Among DEGs, 82 unigenes were identified as being closely involved in de novo FA and triacylglycerol(TAG) biosynthesis. Surprisingly, among DEGs involved in TAG biosynthesis, expression of unigenes encoding GPATs(glycerol-3-phosphate acyltransferase) were relatively low and unigenes encoding LPAATs(lysophosphatidic acid acyltransferase) were highly expressed, suggesting that LPAAT contributed more in storage lipids metabolism in C. humilis seed. Genes encoding DGAT2(diacylgycerol acyltransferase2) were the most highly expressed while expression of DGAT1 was very low, suggesting DGAT2 was the dominant DGAT which catalyzed TAG biosynthesis. To verify these results,10 unigenes were selected and their expression patterns were analyzed by quantitative RTPCR. These data provided comprehensive information for understanding the molecular mechanism of FA and TAG biosynthesis in C. humilis seed.

Adult-repopulating lymphoid potential of yolk sac blood vessels is not confined to arterial endothelial cells

During embryogenesis,hematopoietic stem progenitor cells(HSPCs)are believed to be derived from hemogenic endothelial cells(HECs).Moreover,arterial feature is proposed to be a prerequisite for HECs to generate HSPCs with lymphoid potential.Although the molecular basis of hematopoietic stem cell-competent HECs has been delicately elucidated within the embryo proper,the functional and molecular characteristics of HECs in the extraembryonic yolk sac(YS)remain largely unresolved.In this study,we initially identified six molecularly different endothelial populations in the midgestational YS through integrated analysis of several single-cell RNA sequencing(scRNA-seq)datasets and validated the arterial vasculature distribution of Gja5+ECs using a Gja5-EGFP reporter mouse model.Further,we explored the hemogenic potential of different EC populations based on their Gja5-EGFP and CD44 expression levels.The hemogenic potential was ubiquitously detected in spatiotemporally different vascular beds on embryonic days(E)8.5–E9.5 and gradually concentrated in CD44-positive ECs from E10.0.Unexpectedly,B-lymphoid potential was detected in the YS ECs as early as E8.5 regardless of their arterial features.Furthermore,the capacity for generating hematopoietic progenitors with in vivo lymphoid potential was found in nonarterial as well as arterial YS ECs on E10.0–E10.5.Importantly,the distinct identities of E10.0–E10.5 HECs between YS and intraembryonic caudal region were revealed by further scRNA-seq analysis.Cumulatively,these findings extend our knowledge regarding the hemogenic potential of ECs from anatomically and molecularly different vascular beds,providing a theoretical basis for better understanding the sources of HSPCs during mammalian development.

Decoding the annulus fibrosus cell atlas by scRNA-seq to develop an inducible composite hydrogel:A novel strategy for disc reconstruction

Low back pain is one of the most serious public health problems worldwide and the major clinical manifestation of intervertebral disc degeneration(IVDD).The key pathological change during IVDD is dysfunction of the annulus fibrosus(AF).However,due to the lack of an in-depth understanding of AF biology,the methods to reconstruct the AF are very limited.In this study,the mice AF cell atlas were decoded by single-cell RNA sequencing to provide a guide for AF reconstruction.The results first identify a new population of AF cells,fibrochondrocyte-like AF cells,which synthesize both collagen Ⅰ and collagen Ⅱ and are potential functional cells for AF reconstruction.According to the dual features of the AF extracellular matrix,a composite hydrogel based on the acylation of methacrylated silk fibroin with methacrylated hyaluronic acid was produced.To obtain the ability to stimulate differentiation,the composite hydrogels were combined with a fibrochondrocyte-inducing supplement.Finally,reconstruction of the AF defects,by the novel AF stem cell-loaded composite hydrogel,could be observed,its amount of chondroid matrices recovered to 31.7% of AF aera which is significantly higher than that in other control groups.In summary,this study decodes the AF cell atlas,based on which a novel strategy for AF reconstruction is proposed.

Soil bacterial communities respond differently to graphene oxide and reduced graphene oxide after 90 days of exposure

Graphene-based nanomaterials(GBNs)are likely to be entering the soil environment in increasing amounts via consumer products.However,the disturbance of bacterial communities and their associated ecological functions by GBNs remains elusive.We performed a soil incubation experiment with the addition of graphene oxide(GO)and reduced graphene oxide(RGO).The Illumina sequencing technique was used to investigate changes in bacterial communities,and the functional groups of the communities were analyzed using the functional annotation of prokaryotic taxa database.After 90 days of exposure,RGO induced a lower bacterial richness than GO.However,GO induced larger changes in community composition and functions than RGO.After exposure to GBNs,some of the functional groups associated with organic matter degradation and biogeochemical cycling of nitrogen and sulfur decreased.However,the functional group associated with aromatic compound degradation increased,possibly because GBNs contain rich aromatic hydrocarbon structures,which are tolerated by this functional group.

Structure-Enhanced Mechanically Robust Graphite Foam with Ultrahigh MnO_(2) Loading for Supercapacitors

With the fast bloom of flexible electronics and green vehicles,it is vitally important to rationally design and facilely construct customized functional materials with excellent mechanical properties as well as high electrochemical performance.Herein,by utilizing two modern industrial techniques,digital light processing(DLP)and chemical vapor deposition(CVD),a unique 3D hollow graphite foam(HGF)is demonstrated,which shows a periodic porous structure and robust mechanical properties.Finite element analysis(FEA)results confirm that the properly designed gyroidal porous structure provides a uniform stress area and mitigates potential structural failure caused by stress concentrations.A typical HGF can show a high Young’s modulus of 3.18 MPa at a low density of 48.2 mg cm^(-3).The porous HGF is further covered by active MnO_(2) material with a high mass loading of 28.2 mg cm^(-2)(141 mg cm^(-3)),and the MnO_(2)/HGF electrode still achieves a satisfactory specific capacitance of 260 F g^(-1),corresponding to a high areal capacitance of 7.35 F cm^(-2) and a high volumetric capacitance of 36.75 F cm^(-3).Furthermore,the assembled quasi-solid-state asymmetric supercapacitor also shows remarkable mechanical properties as well as electrochemical performance.

Heterogeneous Catalysts toward CO_(2) Hydrogenation for Sustainable Carbon Cycle

Fossil fuels such as coal,oil,and natural gas have been increasingly consumed and depleted for the use as energy and raw materials,thus compelling the search for the substitutes.Notably,we are unable to produce energy,but only collect what nature gives us.To attain a sustainable development,we should use renewable energy to close the loop of materials,especially for carbon as the origin of life.Among diversified carbon-based chemicals,CO_(2) is the end product of any combustion process,either biological or chemical.