检索结果-南通市图书馆

Effect of Cryst.llization Conditions on Polymorphic Diversity of Malic Acid RS-Racemate

Transactions of Tianjin University 2013年第2期19卷 86-91页

作者： Isakov A I Kotelnikova E N Kryuchkova L Yu Lorenz H st.petersburg st.te University St.Petersburg 199034Russia Max Planck institute for Dynamics of Complex Technical Syst.ms Magdeburg 39106Germany

Enantiomers （R （＋） and S（-））, RS-racemate mixture of enantiomers） of malic acid C4H605 have been （double compound） and （R ＋ S） -conglomerate （mechanical invest.gated by means of X-ray diffractometry and high tern- perature X-ray diffraction method. The RS-racemate was found to be able to form three polymorphic modifications, which we denominated as M1 （monoclinic, space group P21/c）, M2 （monoclinic, space group Cc）, and Tc （triclinic, space group P-l ）, the latter modification having been unknown before. Modification Tc was also described, and its X- ray diffraction characterist.cs, including interplanar spacings d, hkl indices, unit cell parameters, were defined. In addi- tion, X-ray diffraction characterist.cs for both reported earlier M1 and M2 monoclinic polymorphic modifications were measured with higher accuracy. The ability of RS-racemate to form one of the above three modifications （MI, M2, and Tc） or their mixtures containing various proportions and combinations of the components （M1 ＋ M2, M1 ＋ Tc, or M2 ＋ Tc） was found to depend on the type of cryst.llization medium （a melt, aqueous medium, ethanol or acetone solu- tion）, cryst.llization rate （from 2--3 minutes to 4 months）, and cryst.llization temperature. Heating S-enantiomer and M1 RS-racemate up to their respective melting points （100 ℃ and 124 ℃, correspondingly） only made them undergo thermal deformations, while heating （R ＋ S） -conglomerate in the temperature range of 96--110 ℃ resulted in its homogenization to form M2 RS-racemate, which, near the melting point （118 ℃）, namely, in the range of 112-116 ℃, was transformed into MI RS-racemate. Keywords： polvmorDhism; racemic, chiral

关键词： polymorphism racemic chiral

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Threshold characterist.cs of short-pulsed loads combined with the ultrasound field causing dynamic delamination of adhesive joints

引用

Theoretical & Applied Mechanics Letters 2018年第1期8卷 28-31页

作者： Nikolai Gorbushin Yuri Petrov Ya-Pu Zhao Yin Zhang st.-petersburg st.te University St.-Petersburg 198504Russia institute of Problems of Mechanical Engineering St.-Petersburg 199178Russia st.te Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing 100080China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

In the present work, we analyse the delamination problem under the combined dynamic load. We show the effect of background harmonic vibrations on critical amplitudes of the principal force pulse. The effect is demonst.ated on the simple model of a st.ing on an elast.c foundation and the fracture phenomenon is predicted by the incubation time criterion. The results st.te the possibility of considerable decrease in threshold amplitude by a proper choice of the frequency of a background excitation.

关键词： Dynamic fracture Incubation time criterion Delamination

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synergist.c effect of chitin nanofibers and polyacrylamide on electrochemical performance of their ternary composite with polypyrrole

引用

Journal of Energy Chemist.y 2018年第3期27卷 843-853页

作者： Michael A.Smirnov Maria P.Sokolova Natalya V.Bobrova Alexander M.Toikka Pierfrancesco Morganti Erkki Lahderanta Lappeenranta University of Technology 53850 LappeenrantaFinland institute of Macromolecular compounds Russian Academy of Sciences199004 Saint PetersburgRussia st.petersburg st.te University PeterhofSaint Petersburg 198504Russia Dermatological institute II University of Naples80138 NaplesItaly

Development of simple methods for preparation of polymeric electrode materials with nanofibrous network st.ucture is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary syst.m demonst.ates better electrochemical performance in comparison with both polypyrrole–polyacrylamide and polypyrrole–chitin binary composites. Possible mechanism of synergist.c effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite＇s st.ucture is *** highest.attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling st.bility with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.

关键词： Energy materials Nanocomposites Natural fibers Electrical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Measurement of the Plasma Rotation Velocity by Using Visible Spectrum on HL-1M Mokamak

引用

Plasma Science and Technology 2001年第2期3卷 683-690页

作者：罗俊林李伟王恩耀董贾福唐年益刘泽田 Southwest.institute of Physics Chengdu 610041 China Ioffe institute of Physics. st. petersburg. Russia 195251

The plasma rotation velocity were measured in HL-1M with Doppler shifts of CⅢ、 C Ⅱ、 O Ⅱ and H. line by a SKD high resolution spectrometer. The effects .of density' hydrogen pellet injection and carbon impurities injected by laser-blow-off on toroidal(V) and poloidal (Vθ)rotation velocity have been observed. The Vθ measured from H. line is only half of that from C Ⅱ impurity line.

关键词： Measurement of the Plasma Rotation Velocity by Using Visible Spectrum on HL-1M Mokamak HL

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of Benzenediols—Pyrocatechol and Resorcinol—On the Resist.nce of Portland Cement Mortars with Aluminum Sulfate to Sulfate Attack

引用

Materials Sciences and Applications 2018年第2期9卷 305-313页

作者： Alexey Brykov Natalia Paritskaya Alexander Velichko Maxim Mokeev Department of Chemist.y of Subst.nces and Materials Saint-Petersburg State Institute of Technology St. Petersburg Russia institute of Macromolecular Compounds St. Petersburg Russia

The effect of benzene-1,2-diol (pyrocatechol) and benzene-1,3-diol (resorcinol) on the development of sulfate attack in Portland cement mortars containing alkali-free setting accelerator (aluminum sulfate) was st.died. It has been found that these compounds (especially pyrocatechol—due to its ability to form chelate complexes with aluminum ions) rest.ain dest.uctive deformations of Portland cement mortars with aluminum sulfate admixture when under test.conditions a const.nt supply of sulfate ions from external source is provided. According to 27Al-MAS NMR data, pyrocatechol does not influence the amount of ettringite formed in Portland cement past. during its st.re in sodium sulfate solution. Presumably, in presence of benzenediols, in cement mortars with aluminum sulfate admixture the formation of ettringite cryst.ls with a less pronounced dest.uctive effect takes place.

关键词： Pyrocatechol Benzenediols Aluminum Sulfate Portland Cement Sulfate Attack Ettringite NMR Spectroscopy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Peculiar Set-Retarding Effect of Miserly Amounts of Pyrocatechol on Calcium Aluminate Cement Hydration

引用

Materials Sciences and Applications 2018年第5期9卷 455-463页

作者： Alexey Brykov Mikhail Voronkov Olga Nekrasova Maxim Mokeev Department of Chemist.y of Subst.nces and Materials Saint-Petersburg State Institute of Technology St. Petersburg Russia institute of Macromolecular Compounds St. Petersburg Russia

Pyrocatechol (benzene-1,2-diol) acts upon a calcium aluminate cement (CAC) as a very st.ong set and hardening retardant and a potent plast.cizing agent at the same time. By st.dying CAC-pyrocatechol compositions using different analytical methods it was shown that pyrocatechol indeed slows CAC hydration and decreases st.ength of hardening st.ne. What makes this behavior a peculiar one is that pyrocatechol is known to accelerate Portland cement (PC) setting drast.cally.

关键词： Pyrocatechol Calcium Aluminate Cements Hydration NMR Spectroscopy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cytomorphological and genetic indicators in the early ontogenesis of the wild and farmed broad whitefish(Coregonus nasus)

引用

渔业学报（英文） 2023年第3期8卷 261-266页

作者： Aleksandr Selyukov Oksana Zhigileva Leonid Shuman Svetlana Selyukova Vera Bogdanova Tyumen st.te University Institute of BiologyPirogov Street 3Tyumen625043Russia st.petersburg Branch of the All-Russian Research institute of Fisheries and Oceanography(st.petersburg Branch of VNIRO) St.Petersburg199155Russia

The qualitative and quantitative composition of primordial germ cells(PGCs)and the genetic variability of embryos of the Coregonus nasus from the Ob river basin and domest.cated population breeding outside the natural areal was *** the broad whitefish,typical,binuclear,polymorphic nuclei cells,as well as PGCs represented primary gonocytes during embryogenesis in *** hatching larvae PGCs mitoses were noted only in domest.cated *** genetic variability of embryos of the broad whitefish was st.died by polymerase chain reaction of inter simple sequence repeats(ISSR-PCR).The high polymorphism of the broad whitefish cultured population was *** proportion of polymorphic bands was 89.4%,Nei’s genetic diversity was *** of the domest.cated broad whitefish did not affect the overall level of polymorphism of neutral DNA *** findings suggest.the preservation of cytomorphological and genetic diversity in *** embryo from different sources.

关键词： Broad whitefish Domest.c brood st.ck Wild population Embryogenesis Genetic polymorphism Primordial germ cells

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Compressor and Turbine Multidisciplinary Design for Highly Efficient Micro-gas Turbine

引用

Journal of Thermal Science 2018年第3期27卷 259-269页

作者： BARSI Dario PERRONE ANDrea QU Yonglei RATTO Luca RICCI Gianluca SERGEEV Vitaliy ZUNINO Pietro Department of Mechanical Energy Management and Transport Engineering Università degli Studi di Genova Faculty of Power and Energy Engineering Harbin Engineering University institute of Energy and Transport Syst.ms "Peter the Great" St. Petersburg Polytechnic University

Multidisciplinary design optimization （MDO） is widely employed to enhance turbomachinery compo- nents efficiency. The aim of this work is to describe a complete tool for the aero-mechanical design of a radial in- flow turbine and a centrifugal compressor. The high rotational speed of such machines and the high exhaust.gas temperature （only for the turbine） expose blades to really high st.esses and therefore the aerodynamics design has to be coupled with the mechanical one through an integrated procedure. The described approach employs a fuUy 3D Reynolds Averaged Navier-st.kes （RANS） solver for the aerodynamics and an open source Finite Element Analysis （FEA） solver for the mechanical integrity assessment. Due to the high computational cost.of both these two solvers, a meta model, such as an artificial neural network （ANN）, is used to speed up the optimization design process. The interaction between two codes, the mesh genera- tion and the post.processing of the results are achieved via in-house developed scripting modules. The obtained results are widely presented and discussed.

关键词： Micro-gas turbine Multidisciplinary Optimization Centrifugal Compressor Centripetal Turbine

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mathematical Programming Method as a Means of Calibration of NIR Analyzers

引用

Journal of Chemist.y and Chemical Engineering 2012年第8期6卷 692-697页

作者： Ilya Skutin Konst.ntin Zharinov Maria Sushkova Department of Chemical Engineering Control St. Petersburg State Institute of Technology St. Petersburg 190013 Russia Lumex Ltd. St. Petersburg 192029 Russia

In addition to the conventional methods of the calibration model const.uction, such as PCR （principal components regression） and PLS （partial least.squares）, a MPM （mathematical programming method） is developed and proposed for practical use in NIR analyses of agricultural and food products. The proposed method involves the mathematical programming techniques to seek the regression coefficients for the calibration model calculation. It is based on the optimization theory used for finding the extremum of the objective function in the given domain of a vector space and employs the method of the complementarity problems solving. The MPM algorithm is described in detail. The MPM was test.d on an InfraLUM FT-10 NIR analyzer of Lumex company with samples of dry milk （for fat）, corn （for protein） and rye flour （for moist.re）. The obtained results show that the MPM can be used for const.ucting multivariate calibrations with the qualitative characterist.cs superior over those of the classical PCR and PLS methods of analysis.

关键词： Chemometrics multivariate calibration mathematical programming simplex table method.

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Probiotics and autoprobiotics for treatment of Helicobacter pylori infection

引用

World Journal of Clinical Cases 2023年第20期11卷 4740-4751页

作者： Natalia V Baryshnikova Anast.sia S Ilina Elena I Ermolenko Yury P Uspenskiy Alexander N Suvorov Department of Molecular Microbiology Institute of Experimental MedicineSt.Petersburg 197376Russia Internal Diseases Department of st.matological Faculty Pavlov First St-Petersburg State Medical UniversitySt.Petersburg 197022Russia Laboratory of Medical and Social Pediatric Problems St-Petersburg State Pediatric Medical UniversitySt.Petersburg 194100Russia Clinical Department Institute of Experimental MedicineSt.Petersburg 197376Russia Department of Faculty Therapy Named After V.A.Valdman St-Petersburg State Pediatric Medical UniversitySt.Petersburg 194100Russia

The article discusses various approaches for probiotic treatment of Helicobacter pylori(***)infection:Probiotics as an adjuvant treatment in the st.ndard eradication therapy;probiotic st.ains as a monotherapy;and autoprobiotics as a *** refer to indigenous bifidobacteria,lactobacilli,or enterococci isolated from a specific individual,intended to rest.re his/her microbiota and improve his/her *** potential mechanisms of probiotic action against.*** include correction of the gut microbiota,immunological effects(enhancement of humoral and cellular immunity,and reduction of oxidative st.ess),direct antagonist.c effects against.***(such as colonization resist.nce and bacteriocin synthesis),and st.mulation of local immunological protection(st.engthening of the mucous protective barrier and reduction of gast.ic mucosa inflammation).The incorporation of probiotics into comprehensive eradication therapy shows promise in optimizing the treatment of *** *** can enhance the eradication rates of ***,reduce the occurrence and severity of side effects,and improve patient *** or autoprobiotic monotherapy can be considered as an alternative treatment approach in cases of allergic reactions and insufficient effectiveness of *** recommend including probiotics as adjunctive medications in *** ***,further randomized multicenter st.dies are necessary to invest.gate the effects of probiotics and autoprobiotics against.***,in order to gain a better underst.nding of their mechanisms of action.

关键词： Helicobacter pylori Probiotic Autoprobiotic Eradication Microbiota Gut Immunity

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：