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Polyisoprene/Nanostructured Carbon Composites for Applications in Temperature Sensors 聚异戊二烯/纳米结构碳复合材料在温度传感器中的应用
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.005
M. Knite, S. Zike, J. Zavickis, A. Linarts
{"title":"Polyisoprene/Nanostructured Carbon Composites for Applications in Temperature Sensors","authors":"M. Knite, S. Zike, J. Zavickis, A. Linarts","doi":"10.7250/MSAC.2013.005","DOIUrl":"https://doi.org/10.7250/MSAC.2013.005","url":null,"abstract":"The studies of electrical properties of the polyisoprene (PI) matrix/high structure carbon black (HSCB) composites (PCBC) with various concentrations (8, 9, 10 and 11 mass parts) of filler have been carried out in the temperature interval of 90K–330K. In this paper we focus on the investigation of direct current (DC) conductivity in a low-temperature region with negative temperature coefficient of resistivity (NTCR). It has been proven that variable range hopping (VRH) conduction is dominated by hopping of carriers among localized states in a low-temperature range. At higher temperatures the nearest neighbour hopping (NNH) conductivity or constant range hopping charge transport takes place. The reversibility as well as small hysteresis of resistance change versus temperature indicates prospective temperature sensor application for PCBC","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"70 1","pages":"29-33"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88506713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
The Synthesis and X-ray Studies of 6-pyrrolidinyl-2-triazolyl Purine Arabinonucleoside 6-吡咯烷基-2-三唑基嘌呤阿拉伯核苷的合成及x射线研究
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.007
Irina Novosjolova, Ē. Bizdēna, S. Belyakov, M. Turks
{"title":"The Synthesis and X-ray Studies of 6-pyrrolidinyl-2-triazolyl Purine Arabinonucleoside","authors":"Irina Novosjolova, Ē. Bizdēna, S. Belyakov, M. Turks","doi":"10.7250/MSAC.2013.007","DOIUrl":"https://doi.org/10.7250/MSAC.2013.007","url":null,"abstract":"C(6)-Pyrrolidinyl derivative with triazolyl moiety at C(2)-position was obtained from 2,6-bis-triazolylpurine arabinonucleoside via C(6)-regioselective nucleophilic substituon of 1,2,3-triazolyl moiety with pyrrolidine. The obtained compound was studied by NMR, X-ray, UV/VIS and emission spectra. Pyranose form of arabinose residue and α-configuration of the obtained compound were unambiguously proven by NMR and X-ray studies.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"22 1","pages":"39-44"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83208102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Synthesis of Enantiomerically Enriched 1,2,3- Triazole-derivatized Homoalanines 对映体富集1,2,3-三唑衍生同丙氨酸的合成
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.004
M. Turks, N. Strelnikova, V. Kumpiņš, U. Kalējs
{"title":"Synthesis of Enantiomerically Enriched 1,2,3- Triazole-derivatized Homoalanines","authors":"M. Turks, N. Strelnikova, V. Kumpiņš, U. Kalējs","doi":"10.7250/MSAC.2013.004","DOIUrl":"https://doi.org/10.7250/MSAC.2013.004","url":null,"abstract":"In recent decades, the synthesis of amino acid – triazole conjugates has become an emerging area. L- and Dazidohomoalanine derivatives readily undergo copper(I)- catalyzed azide-alkyne dipolar cycloaddition reaction. The expected 4-substituted-1H-1,2,3-triazol-1-yl-homoalanines are obtained in the reactions of either N- and O-protected or protecting-group-free azidohomoalanines with various alkynes. 1,2,3-Triazole conjugate formation tolerates various functional groups. The synthetic approach that uses N- and O-protected starting materials relays on the standard chromatographic purification of intermediates that are further deprotected by hydrogenolysis. In this way, the purification of final products is not required. The synthetic approach that uses protecting-groupfree azidohomoalanine is faster from a synthetic point of view as it includes only one step. However, the purification of protectinggroup- free amino acid derivatives is laborious. Additionally, we have shown that the chiral stationary phase CROWNPAK® CR(+), which is based on chiral crown ether as a selector, is applicable for direct chromatographic determination of enantiomeric ratio of the title products.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"31 1","pages":"21-28"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74538300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Catalytic Etherification of Glycerol with Alcohols 甘油与醇的催化醚化反应
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.011
M. Roze, V. Kampars, K. Teivena, R. Kampare, E. Liepiņš
{"title":"Catalytic Etherification of Glycerol with Alcohols","authors":"M. Roze, V. Kampars, K. Teivena, R. Kampare, E. Liepiņš","doi":"10.7250/MSAC.2013.011","DOIUrl":"https://doi.org/10.7250/MSAC.2013.011","url":null,"abstract":"Glycerol ethers could be the good fuel additives. In recent years, the etherification of glycerol has been widely investigated. We tried to perform the synthesis of glycerol ethers using different alcohols – ethanol, isopropanol, tert-butanol. Amberlyst-15, Amberlyst-36, Montmorillonite K 10, β-zeolite were used as catalysts. The etherification reaction between glycerol and alcohols was carried out under atmospheric pressure, by operating at different temperatures ranging from 60 °C to boiling temperatures, at different reaction times and at both different catalyst/glycerol and alcohol/glycerol rates. We also tried to perform this reaction using ultrasonic and microwave conditions. The best results were achieved, when toluene as a solvent and Amberlyst-36 as a catalyst were used.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"15 1","pages":"67-72"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80912289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 22
Crushing of Mineral Particles by Control of Their Kinetic Energy 控制矿物颗粒的动能粉碎
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.010
E. Stamboliadis, Dimitris Stamboliadis, K. Kiskira, C. Emejulu
{"title":"Crushing of Mineral Particles by Control of Their Kinetic Energy","authors":"E. Stamboliadis, Dimitris Stamboliadis, K. Kiskira, C. Emejulu","doi":"10.7250/MSAC.2013.010","DOIUrl":"https://doi.org/10.7250/MSAC.2013.010","url":null,"abstract":"The present paper studies the energy size relationship of minerals using a specially designed centrifugal crusher with rotation frequency control. The feed particles are accelerated by the rotating disc of the crusher and they crush on the opposite vertical wall having the predetermined specific kinetic energy. The mathematical modelling shows that the specific energy, energy per unit mass of the particles, is independent of their mass and is calculated to depend on the rotation frequency and the disc diameter. Crystalline limestone, marly limestone and serpentine samples are tested. The results obtained are used to present the energy–size relationship and to compare the crushing amenability of the rocks tested. A suggestion for further study is to derive the mathematical model of the breakage curves and to calculate the breakage energy for each size class using the model to be proposed.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"12 1","pages":"58-66"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73177173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Low-temperature Hydraulic Binders for Restoration Needs 用于修复需要的低温液压粘合剂
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.001
I. Barbane, I. Vītiņa, L. Krāģe
{"title":"Low-temperature Hydraulic Binders for Restoration Needs","authors":"I. Barbane, I. Vītiņa, L. Krāģe","doi":"10.7250/MSAC.2013.001","DOIUrl":"https://doi.org/10.7250/MSAC.2013.001","url":null,"abstract":"The late 19th/ early 20th century was a period of active usage of low-temperature hydraulic binders, e.g., Roman cement, for the construction of buildings. Dolomitic Roman cement was characteristic of Latvia in contrast to the rest of Europe, where calcitic Roman cement was applied. The research has been conducted with the aim to synthesize a binder from local clay and dolomite compatible with historical dolomitic Roman cement. The results of chemical and XRD phase analyses have approved that Devonian as well as Quaternary clay mixed with dolomite can form a binder that closely conforms with historical ones. The obtained compositions can be considered perspective for restoration needs.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"1 1","pages":"5-9"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83463369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
The Synthesis and Structure of Palladium 2,4-dimethyl-8-hydroselenoquinolinate 2,4-二甲基-8-氢硒喹啉酸钯的合成与结构
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.008
E. Silina, S. Belyakov, A. Tokmakov, D. Zaruma
{"title":"The Synthesis and Structure of Palladium 2,4-dimethyl-8-hydroselenoquinolinate","authors":"E. Silina, S. Belyakov, A. Tokmakov, D. Zaruma","doi":"10.7250/MSAC.2013.008","DOIUrl":"https://doi.org/10.7250/MSAC.2013.008","url":null,"abstract":"The internal complex palladium 2,4-dimethyl-8- hydroselenoquinolinate Pd[C9H4(CH3)2NSe]2 (I) has been synthesized in the course of study of the complexing activity of 8- hydroselenoquinoline and investigation of the nature of chemical bond metal-selenium in the five-membered metal-containing ring. X-ray diffraction data for I: Monoclinic, space group P21/n, a = 9.0092(4), b = 16.3290(7), c = 14.1073(6) A,  = 106.710(2)o, V = 1987.7(2) A3, Z = 4, R1=0.0477, wR2=0.1182 for 4499 reflections (diffractometer Bruker-Nonius KappaCCD, MoK). The crystal structure of the complex I is formed by neutral asymmetric molecules Pd[C9H4(CH3)2NSe]2 in which the central atom palladium is connected bidentically (Se,N) with two 2,4- dimethyl-8-hydroselenoquinoline ligands. The structure of palladium coordination polyhedron is cis-square (2Se+2N) somewhat tetrahedrally distorted. Dihedral angle between the SePdN / SePdN coordination planes is 20.15(1)o. The Pd–Se and Pd–N bonds are covalent. The transition of trans- (complex Pd(C9H6NSe)2 (II) to cis-coordination (complex I) causes the weakening of the Pd–N bonds (compare 2.162(5) and 2.159(5) A (I) , 2.065(3) A (II) ).","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"30 1","pages":"45-50"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87142366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Bio-based Natural Fibre Reinforced Green Composites 生物基天然纤维增强绿色复合材料
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.002
A. Voronova, Ance Ziemele, A. Dzene, V. Tupureina
{"title":"Bio-based Natural Fibre Reinforced Green Composites","authors":"A. Voronova, Ance Ziemele, A. Dzene, V. Tupureina","doi":"10.7250/MSAC.2013.002","DOIUrl":"https://doi.org/10.7250/MSAC.2013.002","url":null,"abstract":"The main goal of the presented study is the development of industrial hemp fibre reinforced biocomposites. Matrix materials used are as follows: thermoplastic starch based systems, blends of biodegradable polymers – poly(vinylalcohol) and microbially produced polyester polyhydroxybutyrate. The correlation among hemp fibre content, matrix composition and characteristics of biocomposites has been demonstrated. Hydrophobic finishing of reinforced biocomposites with Rucostar DDD diminishes moisture absorption. Biodegradation of biocomposites has been found to be composition dependent.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"60 1","pages":"10-14"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80785873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Study of Magnesium Substitution Effect on Physicochemical Properties of Hydroxyapatite 镁取代对羟基磷灰石理化性质影响的研究
Materials Science and Applied Chemistry Pub Date : 2013-10-18 DOI: 10.7250/MSAC.2013.009
L. Stīpniece, Kristīne Šalma-Ancāne, D. Jakovļevs, Natālija Borodajenko, L. Bērziņa-Cimdiņa
{"title":"The Study of Magnesium Substitution Effect on Physicochemical Properties of Hydroxyapatite","authors":"L. Stīpniece, Kristīne Šalma-Ancāne, D. Jakovļevs, Natālija Borodajenko, L. Bērziņa-Cimdiņa","doi":"10.7250/MSAC.2013.009","DOIUrl":"https://doi.org/10.7250/MSAC.2013.009","url":null,"abstract":"In the present study, pure and Mg-substituted hydroxyapatite powders made up of needle-like and plate-like particles, respectively, have been synthesized by wet chemical precipitation of CaO, MgO and H3PO4. The influence of different amounts of MgO addition into synthesis media on properties of as-synthesized and sintered powders has been evaluated. Through the phase and chemical composition analysis it has been determined that the prepared powders contain various amounts of Mg (in the range between 0.21–4.72 wt%). The substitution of Mg promoted the decomposition of hydroxyapatite to β-tricalcium phosphate.","PeriodicalId":18239,"journal":{"name":"Materials Science and Applied Chemistry","volume":"147 1","pages":"51-57"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89532181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
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