高塑性Mg-3Zn-1Y-1Mn合金在不同挤压温度下的组织演变、强化机制和变形行为

为了改善铸态Mg-3Zn-1Y-1Mn合金的力学性能、研究合金在不同变形温度下的组织演变规律和变形机理,对铸态Mg-3Zn-1Y-1Mn合金进行热挤压实验。实验结果显示,当挤压温度为330℃时,挤压态合金具有最佳的力学性能,抗拉强度和伸长率分别达到270 MPa和16.8%。挤压态合金性能大幅提高主要归因于3个方面:由动态再结晶导致的细晶强化作用、未被动态再结晶抵消的加工硬化以及第二相粒子强化作用。在热挤压过程中,当挤压温度为300℃时,同时发生连续动态再结晶和动态回复;而当挤压温度为330和360℃时,发生不连续动态再结晶。此外,在热变形过程中{0001}基面滑移、{10 10}Ⅰ型柱面滑移和{11 20}Ⅱ型柱面滑移对塑性变形的贡献受挤压温度影响很大,而{11 20}Ⅱ型柱面是3个滑移系中最难启动的滑移系。

Interferon-gamma and tumor necrosis factor-alpha synergistically enhance the immunosuppressive capacity of human umbilical-cordderived mesenchymal stem cells by increasing PD-L1 expression

BACKGROUND The immunosuppressive capacity of mesenchymal stem cells(MSCs)is dependent on the“license”of several proinflammatory factors to express immunosuppressive factors such as programmed cell death 1 ligand 1(PD-L1),which determines the clinical therapeutic efficacy of MSCs for inflammatory or immune diseases.In MSCs,interferon-gamma(IFN-γ)is a key inducer of PD-L1 expression,which is synergistically enhanced by tumor necrosis factor-alpha(TNF-α);however,the underlying mechanism is unclear.AIM To reveal the mechanism of pretreated MSCs express high PD-L1 and explore the application of pretreated MSCs in ulcerative colitis.METHODS We assessed PD-L1 expression in human umbilical-cord-derived MSCs(hUC-MSCs)induced by IFN-γand TNF-α,alone or in combination.Additionally,we performed signal pathway inhibitor experiments as well as RNA interference experiments to elucidate the molecular mechanism by which IFN-γalone or in combination with TNF-αinduces PD-L1 expression.Moreover,we used luciferase reporter gene experiments to verify the binding sites of the transcription factors of each signal transduction pathway to the targeted gene promoters.Finally,we evaluated the immunosuppressive capacity of hUC-MSCs treated with IFN-γand TNF-αin both an in vitro mixed lymphocyte culture assay,and in vivo in mice with dextran sulfate sodium-induced acute colitis.RESULTS Our results suggest that IFN-γinduction alone upregulates PD-L1 expression in hUC-MSCs while TNF-αalone does not,and that the co-induction of IFN-γand TNF-αpromotes higher expression of PD-L1.IFN-γinduces hUCMSCs to express PD-L1,in which IFN-γactivates the JAK/STAT1 signaling pathway,up-regulates the expression of the interferon regulatory factor 1(IRF1)transcription factor,promotes the binding of IRF1 and the PD-L1 gene promoter,and finally promotes PD-L1 mRNA.Although TNF-αalone did not induce PD-L1 expression in hUCMSCs,the addition of TNF-αsignificantly enhanced IFN-γ-induced JAK/STAT1/IRF1 activation.TNF-αupregulated IFN-γreceptor expression through activation of the nuclear factor kappa-B signaling pathway,which significantly enhanced IFN-γsignaling.Finally,co-induced hUC-MSCs have a stronger inhibitory effect on lymphocyte proliferation,and significantly ameliorate weight loss,mucosal damage,inflammatory cell infiltration,and up-regulation of inflammatory factors in colitis mice.CONCLUSION Overall,our results suggest that IFN-γand TNF-αenhance both the immunosuppressive ability of hUC-MSCs and their efficacy in ulcerative colitis by synergistically inducing high expression of PD-L1.

Microstructure and dry sliding wear behavior of cast Al-Mg_2Si in-situ metal matrix composite modified by Nd

The microstructure and dry sliding wear behav- ior of cast Al-18 wt% MgaSi in-situ metal matrix com- posite modified by Nd were investigated. Experimental results show that, after introducing a proper amount of Nd, both primary and eutectic Mg2Si in the Al-18 wt% Mg2Si composite are well modified. The morphology of primary Mg2Si is changed from irregular or dendritic to polyhedral shape, and its average particle size is signifi- cantly decreased. Moreover, the morphology of the eutectic MgzSi phase is altered from flake-like to very short fibrous or dot-like. The wear rates and friction coefficient of the composites with Nd are lower than those without Nd. Furthermore, the addition of 0.5 wt% Nd changes the wear mechanism of the composite from the combination of abrasive, adhesive, and delamination wear without Nd into a single mild abrasion wear with 0.5 wt% Nd.

Differentiation of atypical hepatic hemangioma from liver metastases: Diagnostic performance of a novel type of color contrast enhanced ultrasound

BACKGROUND In clinical practice,the diagnosis is sometimes difficult with contrast-enhanced ultrasound(CEUS)when the case has an atypical perfusion pattern.Color parametric imaging(CPI)is an analysis software for CEUS with better detection of temporal differences in CEUS imaging using arbitrary colors.It measures the differences in arrival time of the contrast agent in lesions so that the perfusion features of atypical hemangioma and colorectal cancer(CRC)liver metastasis can be distinguished.AIM To evaluate the role of a novel type of CPI of CEUS in the differential diagnosis of atypical hemangioma from liver metastases in patients with a history of CRC.METHODS From January 2016 to July 2018,42 patients including 20 cases of atypical hemangioma and 22 cases of liver metastases from CRC were enrolled.These patients had a mean age of 60.5±9.3 years(range:39-75 years).All patients received ultrasound,CEUS and CPI examinations.Resident and staff radiologists independently and retrospectively reviewed CEUS and CPI images.Two sets of criteria were assigned:(1)Routine CEUS alone;and(2)CEUS and CPI.The diagnostic sensitivity,specificity,accuracy and receiver operating characteristic(ROC)curve of resident and staff radiologists were analyzed.RESULTS The following CPI features were significantly different between liver hemangioma and liver metastases analyzed by staff and resident radiologists:Peripheral nodular enhancement(65%-70.0%vs 4.5%-13.6%,P<0.001,P=0.001),mosaic/chaotic enhancement(5%-10%vs 68.2%-63.6%,P<0.001,P<0.001)and feeding artery(20%vs 59.1%-54.5%,P=0.010,P=0.021).CPI imaging offered significant improvements in detection rates compared with routine CEUS in both resident and staff groups.By resident radiologists,the specificity and accuracy of CEUS+CPI were significantly increased compared with that of CEUS(77.3%vs 45.5%,P=0.030;78.6%vs 50.0%,P=0.006).In addition,the area under the curve(AUC)of CEUS+CPI was significantly higher than that of CEUS(0.803 vs 0.757,P=0.036).By staff radiologists,accuracy was improved in CEUS+CPI(81.0%vs 54.8%,P=0.010),whereas no significant differences in specificity and sensitivity were found(P=0.144,P=0.112).The AUC of CEUS+CPI was significantly higher than that of CEUS(0.890 vs 0.825,P=0.013)by staff radiologists.CONCLUSION Compared with routine CEUS,CPI could provide specific information on the hemodynamic features of liver lesions and help to differentiate atypical hemangioma from liver metastases in patients with CRC,even for senior radiologists.

Generation and transformation ofα-oxy carbene intermediates enabled by copper-catalyzed carbonylation

Since the Fischer-Tropsch reaction was discovered by Otto Roelen in 1938,transition metal-catalyzed carbo-nylation reactions come in as one of the most important methods for preparing carbonyl-containing and carbon chain-increased compounds.As a result,the field of carbonylation research has received considerable attention over the past decades and continues to increase.With the continuous development of carbonylation and the in-depth study of the mechanism,more mechanistic details and variations have been revealed,which provide more possibilities for organic synthesis.Recently,copper catalysis has been introduced to the carbonylative functio-nalization of alkenes,thus enabling the rapid assembly of functionalized carbonyl compounds from simple starting materials.In this Account,we summarize the new findings in the Cu-catalyzed borocarbonylation of alkenes based on the generation and transformation ofα-oxy carbene intermediates.We believe that the results presented in this Account will further inspire the design of new carbonylation reactions.

Copper-Catalyzed Ligand-Controlled Selective Borocarbonylation of α-Substituted Styrenes Toward β-Boryl Aldehydes and Cyclopropyl Boronate Esters

We report a copper-catalyzed ligand-controlled selective carbonylative borofunctionalization ofα-substituted styrenes.This reaction provides a general and versatile procedure to synthesize a variety of synthetically usefulβ-boryl quaternary aldehydes and cyclopropyl boronate esters bearing a quaternary carbon center.With NHC(IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene)as the ligand,the carbene intermediate reacts with O-H bond of alcohol while the carbene intermediate would undergo C-H bond insertion when using phosphine ligand[1,2-bis(diphenylphospino)ethane]as the ligand.Formation of a carbene intermediate has been proposed as the key step for this transformation.

Convenient Synthesis of Thioester-Substituted Oxindoles by Palladium-Catalyzed Thiocarbonylative Cyclization with Sulfonyl Chlorides as the Sulfur Source

A general and straightforward strategy for the synthesis of thioester-substituted oxindoles via a palladium-catalyzed thiocarbonyla-tive cyclization process has been developed.With sulfonyl chlorides as promising sulfur source,a wide range of thioester-substituted oxindoles were obtained in moderate to high yields.Both aryl and alkyl sulfonyl chlorides were well tolerated,and Mo(CO)6 played a dual role as both a CO source and a reductant in this approach.

Palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids:Construction of carbonyl-containing indolo[2,1-a]isoquinoline derivatives

A novel palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids is described,which provides a facile approach to access indolo[2,1-a]isoquinoline scaffolds.This method employs benzene-1,3,5-triyl triformate(TFBen)as the CO surrogate for the incorporation of a carbonyl group into indolo[2,1-a]isoquinoline scaffolds,and a variety of carbonyl-containing indolo[2,1-a]isoquinoline derivatives are prepared in good yields.

Difluoroalkylative carbonylation of alkenes to access carbonyl difluoro-containing heterocycles:convenient synthesis of gemigliptin

Fluorinated heterocycles play a vital role in pharmaceutical and agrochemical industries.Hence,rapid and efficient construction of fluorinated heterocycles remains highly demanded.Herein,a difluoroalkylative carbonylative cyclization of unactivated alkenes and ethylene gas enabled by palladium catalysis has been developed for the first time toward the synthesis ofα-carbonyl difluoro-modified glutarimides.This procedure can also be applied to the synthesis of Ge Migliptin which is a medicine approved for the treatment of type 2 diabetes mellitus.

Synthesis of 2-Trifluoromethyl-4-aminoquinolines via Heating-Promoted Multi-component Reaction of CF_(3)-Imidoyl Sulfoxonium Ylides and Amines with Difluorocarbene as a C1 Synthon

A thermally-induced multi-component reaction of CF_(3)-substituted imidoyl sulfoxonium ylides(TFISYs),amines and(triphenylphosphonio)difluoroacetate(PDFA)has been developed,allowing a facile access to 2-trifluoromethyl-4-aminoquinolines in high yields.The reaction proceeds smoothly with or without the addition of sulfur and utilizes difluorocarbene as a C1 synthon under simply heating conditions.Mechanistic study reveals that in-situ generated thiocarbonyl fluoride,isothiocyanate or gem-difluoroalkene might act as the key reaction intermediates.

Accumulation of 1-deoxynojirimycin in silkworm,Bombyx mori L.

1-deoxynojirimycin (1-DNJ) contents in the silkworm,Bombyx mori,at different developmental stages and tissues were investigated by using reverse-phase high-performance liquid chromatography. The 1-DNJ contents of silkworm larvae change significantly with their developmental stages. The male larvae showed higher accumulation efficiency of 1-DNJ than the females and also a significant variation was observed among the silkworm strains. The present results show that tissue distribution of 1-DNJ was significantly higher in blood,digestive juice,and alimentary canal,but no 1-DNJ was observed in the silkgland. Moreover,1-DNJ was not found in silkworms fed with artificial diet that does not contain mulberry leaf powder. This proves that silkworms obtain 1-DNJ from mulberry leaves; they could not synthesize 1-DNJ by themselves. The accumulation and excretion of 1-DNJ change periodically during the larval stage. There was no 1-DNJ in the newly-hatched larvae and 1-DNJ was mainly accumulated during the early and middle stages of every instar,while excreted at later stages of larval development. Further,it is possible to extract 1-DNJ from the larval feces and it is optimal to develop the 1-DNJ related products for diabetic auxiliary therapy.

C–F bond activation under transition-metal-free conditions

The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse C–F bond activation techniques.Although many advances have been made in functionalizations of activated C–F bonds utilizing transition metal complexes,there are fewer approaches available for nonactivated C–F bonds due to the difficulty in oxidative addition of transition metals to the inert C–F bonds.In this regard,using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C–F bonds.Meanwhile,these transition-metal-free processes are greener,economical,and for the pharmaceutical industry,without heavy metal residues.This review provides an overview of recent C–F bond activations and functionalizations under transition-metal-free conditions.The key mechanisms involved are demonstrated and discussed in detail.Finally,a brief discussion on the existing limitations of this field and our perspective are presented.

Radical Carbonylation under Low CO Pressure:Synthesis of Esters from Activated Alkylamines at Transition Metal-Free Conditions

Main observation and conclusion High CO pressure(>40 bar)is usually needed in radical carbonylation reactions in the absence of metal catalyst.In this communication,we developed a transition-metal-free radical carbonylation of activated alkylamines with phenols and alcohols under low CO pressure(1-6 bar).Various esters were obtained in moderate to excellent yields under simple reaction conditions with good functional group compatibility.

Palladium-catalyzed enantioselective carbonylation reactions

Carbonylation,one of the most powerful approaches to the preparation of carbonylated compounds,has received significant attention from researchers active in various fields.Indeed,impressive progress has been made on this subject over the past few decades.Among the various types of carbonylation reactions,asymmetric carbonylation is a straightforward methodology for constructing chiral compounds.Although rhodium-catalyzed enantioselective hydroformylations have been discussed in several elegant reviews,a general review on palladium-catalyzed asymmetric carbonylations is still missing.In this review,we summarize and discuss recent achievements in palladium-catalyzed asymmetric carbonylation reactions.Notably,this review’s contents are categorized by reaction type.

Copper-Catalyzed Carbonylative Synthesis of β-Boryl Amides via Boroamidation of Alkenes

β-Boryl amide is a class of high value intermediates in organic chemistry.In this work,a copper-catalyzed carbonylative boroamidation of olefins toward the synthesize ofβ-boryl amides has been developed.Several new chemical bonds were constructed in this transformation.A wide range ofβ-boryl amides were produced in excellent regioselectivity and good to excellent yields.Ethylene gas can be successfully transformed under the same standard conditions as well.Notably,with the use of a chiral ligand,the first example of enantioselective carbonylative boroamidation of alkenes was realized.In addition,Piposulfan and Pipobroman,antineoplastic medicines,were prepared by this methodology in a straightforward manner.

Elemental Sulfur and Dimethyl Sulfoxide-Promoted Oxidative Cyclization of Trifluoroacetimidohydrazides with Methylheta-renes for the Synthesis of 3-Hetaryl-5-trifluoromethyl-1,2,4-triazoles

A metal-free approach for the synthesis of 3-hetaryl-5-trifluoromethyl-1,2,4-triazoles via sulfur/dimethyl sulfoxide-promoted oxidative cyclization of readily available trifluoroacetimidohydrazides with methylhetarenes has been developed.This transformation proceeds in cascade sulfur-mediated generation of thioaldehyde,condensation,intramolecular cyclization and oxidative aromatization sequence.

Immobilization of foreign protein into polyhedra of Bombyx mori nucleopolyhedrovirus(BmNPV)

In the late phase of Bombyx mori nucleopolyhedrovirus(BmNPV)infection,a large amount of polyhedra appear in the infected cell nucleolus,these polyhedra being dense protein crystals protecting the incorporated virions from the harsh environment.To investigate whether the foreign protein could be immobilized into the polyhedra of BmNPV,two recombinant baculoviruses were generated by a novel BmNPV polyhedrin-plus(polh +)Bac-to-Bac system,designated as vBmBac(polh +)-enhanced green fluorescent protein(EGFP)and vBmBac(polh +)-LacZ,which can express the polyhedrin and foreign protein simultaneously.Light microscopy analysis showed that all viruses produced polyhedra of normal appearance.Green fluorescence can be apparently detected on the surface of the vBmBac(polh +)-EGFP polyhedra,but not the BmNPV polyhedra.Fluorescence analysis and anti-desiccation testing confirmed that EGFP was embedded in the polyhedra.As expected,the vBmBac(polh +)-LacZ polyhedra contained an amount of LacZ and had a higherβ-galactosidase activity.Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)and Western blotting were also performed to verify if the foreign proteins were immobilized into polyhedra.This study provides a new inspiration for efficient preservation of useful proteins and development of new pesticides with toxic proteins.

Synthesis of quinazolinones from o-aminobenzamides and benzyl amines under metal-free conditions

A convenient and transition-metal free protocol for quinazolinones synthesis with o-aminobenzamides and benzyl amines as substrates has been developed. Using H;O;as the oxidant, various quinazolinones were obtained in moderate to good yields under metal- and additive-free conditions.

PSO Optimal Control of Model-free Adaptive Control for PVC Polymerization Process

Polyvinyl chloride （PVC） polymerizing process is a typical complicated industrial process with the characteristics of large inertia, big time delay and nonlinearity. Firstly, for the general nonlinear and discrete time system, a design scheme of model-free adaptive （MFA） controller is given. Then, particle swarm optimization （PSO） algorithm is applied to optimizing and setting the key parameters for controller tuning. After that, the MFA controller is used to control the system of polymerizing temperature. Finally, simulation results are given to show that the MAC strategy based on PSO obtains a good controlling performance index.

Shotgun proteomic analysis of Bombyx mori brain： emphasis on regulation of behavior and development of the nervous system

The insect brain plays crucial roles in the regulation of growth and develop- ment and in all types of behavior. We used sodium dodecyl sulfate polyacrylamide gel electrophoresis and high-performance liquid chromatography - electron spray ionization tandem mass spectrometry （ESI-MS/MS） shotgun to identify the proteome of the silkworm brain, to investigate its protein composition and to understand their biological functions. A total of 2210 proteins with molecular weights in the range of 5.64-1539.82 kDa and isoelectric points in the range of 3.78-12.55 were identified. These proteins were anno- tated according to Gene Ontology Annotation into the categories of molecular function, biological process and cellular component. We characterized two categories of proteins： one includes behavior-related proteins involved in the regulation of behaviors, such as locomotion, reproduction and learning; the other consists of proteins related to the devel- opment or function of the nervous system. The identified proteins were classified into 283 different pathways according to KEGG analysis, including the PI3K-Akt signaling path- way which plays a crucial role in mediating survival signals in a wide range of neuronal cell types. This extensive protein profile provides a basis for further understanding of the physiological functions in the silkworm brain.