检索结果-南通市图书馆

Effect of a Hybrid Zinc Stearate-Silver System on the Properties of Polylactide and Its Abiotic and the Biotic Degradation and Antimicrobial Activity Thereof

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第8期36卷 925-933页

作者： Gabriela Jandikova petra Stoplova Antonio Di Martino petr Stloukal Pavel Kucharczyk Michal Machovsky Vladimir Sedlarik Centre of Polymer Systems University Institute Tomas Bata University in Zlin tr. Tomas Bati 5678 760 O1 Zlin Czech Republic

This work investigates the degradation and properties of a thermoplastically prepared composite comprising a polylactide/ hybrid zinc stearate-silver system. The influence of the zinc stearate-silver system on the properties of the composite is investigated by electron microscopy, differential scanning calorimetry and tensile tests. Furthermore, the antimicrobial activities of the systems are examined. The degradation behaviour of the composites is studied in both abiotic and biotic （composting） environments at an elevated temperature of 58 ℃. The results reveal good dispersion of the additive in the PLA matrix, a stabilizing effect exerted by the same on the polylactide matrix during processing, and slight reduction in glass transition temperature. The zinc stearate-silver component also reduces brittleness and extends elongation of the composite. Abiotic hydrolysis is not significantly affected, which is in contrast with pure PLA, although mineralization during the early stage of biodegradation increases noticeably. The composite exhibits antimicrobial activity, even at the lowest dosage of the zinc stearate/silver component （1 wt%）. Moreover, Ag and Zn contents were found to be present in the composite during abiotic hydrolysis, which was demonstrated by minimal diffusion of Ag ions from the matrix and very extensive washing of compounds that contained Zn.

关键词： Polylactide Composite Biodegradation Zinc stearate Silver Antimicrobial

Epigenetic and non-epigenetic mode of SIRT1 action during oocyte meiosis progression

在线全文

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2019年第4期10卷 895-906页

作者： Jan Nevoral Lukas Landsmann Miriam Stiavnicka petr Hosek Jiri Moravec Sarka Prokesova Hedvika Rimnacova Eliska Koutna Pavel Klein Kristyna Hoskova Tereza Zalmanova Tereza Fenclova Jaroslav petr Milena Kralickova Biomedical Center Faculty of Medicine in PilsenCharles Universityalej Svobody 1655/7632300 PilsenCzech Republic Department of Histology and Embryology Faculty of Medicine in PilsenCharles UniversityKarlovarska 4830166 PilsenCzech Republic Faculty of Science Charles UniversityAlbertov 2038/612800 PragueCzech Republic Faculty of Agriculture Food and Natural ResourcesCzech University of Life Sciences in PragueKamycka 12916500 Praha-SuchdolCzech Republic Institute of Animal Science Pratelstvi 815/10710400Prague 10-UhrinevesCzech Republic

Background: SIRT1 histone deacetylase acts on many epigenetic and non-epigenetic targets. It is thought that SIRT1 is involved in oocyte maturation;therefore, the importance of the ooplasmic SIRT1 pool for the further fate of mature oocytes has been strongly suggested. We hypothesised that SIRT1 plays the role of a signalling molecule in mature oocytes through selected epigenetic and non-epigenetic ***: We observed SIRT1 re-localisation in mature oocytes and its association with spindle *** mature oocytes, SIRT1 distribution shows a spindle-like pattern, and spindle-specific SIRT1 action decreasesα-tubulin acetylation. Based on the observation of the histone code in immature and mature oocytes, we suggest that SIRT1 is mostly predestined for an epigenetic mode of action in the germinal vesicles(GVs) of immature oocytes. Accordingly, BML-278-driven trimethylation of lysine K9 in histone H3 in mature oocytes is considered to be a result of GV epigenetic ***: Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocytes,which can be readily switched from the epigenetic to non-epigenetic mode of action depending on the progress of meiosis.

关键词： Epigenetics Histone code In vitro maturation Oocyte SIRT1 Sirtuin 1

Fractionation and fixation of rare earth elements in soils:Effect of spiking with lanthanum,cerium,and neodymium chlorides

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第1期40卷 143-152页

作者： Olga B.Rogova petr S.Fedotov Rustam Kh.Dzhenloda Vasily K.Karandashev V.V.Dokuchaev Soil Science Institute Russian Academy of Sciences7 Building 2 Pyzhevskiy Side StreetMoscow119017Russia V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry Russian Academy of Sciences19 Kosygin StreetMoscow119991 Russia National University of Science and Technology'MISiS' 4 Leninsky ProspectMoscow119049Russia The Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences6 Institution StreetChernogolovka142432Russia

Industrial and agricultural activities lead to the release of rare earth elements(REEs)in wastewater and aquatic ecosystems,and their accumulation in ***,the behavior of REEs in soils remains somewhat *** the present work the fractionation and fixation of REEs in soddy-podzolic and chernozem soils spiked with La,Ce,and Nd chlorides were studied using dynamic(continuous flow)extraction,which allows natural conditions to be mimicked and artefacts to be *** eluents applied are aimed to dissolve exchangeable,specifically sorbed,bound to Mn oxides,bound to metal-organic complexes,and bound to amorphous and poorly ordered Fe/Al oxides fractions extractable by 0.05 mol/L Ca(NO_(3))2,0.43 mol/L CH_(3)COOH,0.1 mol/L NH_(2)OH·HCl,0.1 mol/L K_(4)P_(2)O_(7) at pH 11,and 0.1 mol/L(NH4)_(2)C_(2)O_(4) at pH 3.2,*** is found that the fixations of added La,Ce,and Nd in the form of metal-organic complexes is predominant for both types of soils:35%-38%in soddy-podzolic soil and 50%-79%in *** fixation of added elements in the first three fractions(exchangeable,specifically sorbed,and bound to Mn oxides)is significant for soddy-podzolic soil(5%-25%).For chernozem,the relative contents of added Ce and Nd in these fractions are nearly *** the content of exchangeable La is notable,about 5%.Adding any of three elements(La,Ce,or Nd)at the level of100 mg/kg to an initial sample results in changing the fractionation and bioaccessibility of other REEs present in *** contents increase in the first three fractions and decrease in fifth(oxalate extractable)fraction for both soddy-podzolic soil and *** main difference is the behavior of REEs in pyrophosphate extractable *** soddy-podzolic soil,adding La,Ce,or Nd results in decreasing the contents of other REEs associated with organic *** chernozem,on the contrary,the contents of REEs in the form of metal-organic complexes slightly *** processes

关键词： Rare earth elements Soddy-podzolic soil Chernozem Fractionation Competitive binding

Development tendencies of moulding and core sands

在线全文

学校读者我要写书评

暂无评论

China Foundry 2011年第4期8卷 438-446页

作者： Stanisaw M.Dobosz petr Jelinek Katarzyna Major-Gabry AGH University of Science and Technology Faculty of Foundry Engineering Department of Moulding Materials Mould Technology and Foundry of Non-ferrous Metals al. A.Mickiewicza 30 30-059 Krakow Poland VB–Ostrava University of Technology FMMI Foundry Department Czech Republic

Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, so that we will reach a point when even processes, that from technological point of view fulfill high requirements of the foundry industry, must be replaced by more ecologically-friendly solutions. Hence, technologies using synthetic resins as binding materials will be limited. This paper presents some predictable development tendencies of moulding and core sands. The increasing role of inorganic substances will be noticed, including silicate binders with significantly improved properties, such as improved knock-out property or higher reclamation strength. Other interesting solutions might also be moulding sands bonded by geo-polymers and phosphate binders or salts and also binders based on degradable biopolymers. These tendencies and the usefulness of these binders are put forward in this paper.

关键词： moulding sand core sand development tendencies

Laparoscopic approach to retrorectal cyst

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2008年第42期14卷 6581-6583页

作者： petra Gunkova Lubomir Martinek Jan Dostalik Igor Gunka petr Vavra Miloslav Mazur Surgical Clinic of the Faculty Hospital Ostrava 17. listopadu 1790 Ostrava Poruba 70800 Czech Republic

Retrorectal cysts are rare benign lesions in the presacral space which are frequently diagnosed in middle-aged females. We report here our experience with two symptomatic female patients who were diagnosed as having a retrorectal cyst and managed using a laparoscopic approach. The two patients were misdiagnosed as having an ovarian cystic lesion after abdominal ultrasonography. Computer tomograghy (CT) scan was mandatory to establish the diagnosis. The trocar port site was the same in both patients. An additional left oophorectomy was done for a coexisting ovarian cystic lesion in one patient in the same setting. There was no postoperative morbidity or mortality and the two patients were discharged on the 5th and 6th post operative days, respectively. Our cases show that laparoscopic management of retrorectal cysts is a safe approach. It reduces surgical trauma and offers an excellent tool for perfect visualization of the deep structures in the presacral space.

关键词： Presacral space Retrorectal cyst Laparoscopy

Garg incontinence scores: New scoring system on the horizon to evaluate fecal incontinence. Will it make a difference?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第3期30卷 204-210页

作者： petr Tsarkov Inna Tulina Parvez Sheikh Darya D Shlyk Pankaj Garg Department of Colorectal Surgery Sechenov First Moscow State Medical UniversityMoscow 119991Russia Department of Oncologic Colorectal Surgery Sechenov First Moscow State Medical UniversityMoscow 119991Russia Department of Colorectal Surgery Saifee HospitalMumbai 400004MaharashtraIndia Department of Colorectal Surgery Garg Fistula Research InstitutePanchkula 134113HaryanaIndia

The main aim of this opinion review is to comment on the recent article published by Garg et al in the World Journal of Gastroenterology 2023;29:4593–*** authors in the published article developed a new scoring system,Garg incon-tinence scores(GIS),for fecal incontinence(FI).FI is a chronic debilitating disease that has a severe negative impact on the quality of life of the *** IV criteria define FI as multiple episodes of solid or liquid stool passed into the clothes at least twice a *** associated social stigmatization often leads to significant under-reporting of the condition,which further impairs *** important point is that the complexity and vagueness of the disease make it difficult for the patients to properly define and report the magnitude of the problem to their *** to this,the management becomes even more *** issue is resolved up to a considerable extent by a scoring *** were several scoring systems in use for the last three *** prominent of them were the Cleveland Clinic scoring system or the Wexner scoring system,*** Hospital or Vaizey’s scores,and the FI severity ***,there were several shortcomings in these scoring *** the opinion review,we tried to analyze the strength of GIS and compare it to the existing scoring *** main pitfalls in the existing scoring systems were that most of them gave equal weightage to different types of FI(solid,liquid,flatus,etc.),were not comprehensive,and took only the surgeon’s perception of FI into *** GIS,almost all shortcomings of previous scoring systems had been addressed:different weights were assigned to different types of FI by a robust statistical methodology;the scoring system was made comprehensive by including all types of FI that were previously omitted(urge,stress and mucus FI)and gave priority to patients’rather than the physicians’perceptions while developing the scoring *** to this,GIS in

关键词： Fecal incontinence Scoring system Urge Stress Flatus

Genetic diversity, population structure, and genome-wide association analysis of ginkgo cultivars

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Horticulture Research 2023年第8期10卷 231-240页

作者： Yaping Hu Zhaoyan Yu Xiaoge Gao Ganping Liu Yun Zhang petr Smarda Qirong Guo Co-Innovation Center for Sustainable Forestry in Southern China Nanjing Forestry UniversityNanjing 210037China Coconut Research Institute of Chinese Academy of Tropical Agricultural Science WenchangHainan 571339China Institute of Grassland Flowersand EcologyBeijing Academy of Agriculture and Forestry SciencesBeijing 100097China Department of Botany and Zoology Faculty of ScienceMasaryk UniversityKoltlárská2Brno 61137Czech Republic

Ginkgo biloba is an economically valuable tree *** species has nearly become extinct during the Quaternary,which has likely resulted in reduction of its genetic *** genetic variability is now conserved in few natural populations in China and a number of cultivars that are,however,derived from a few ancient trees,helping the species survive in China through medieval *** the recent interest in ginkgo,however,detailed knowledge of its genetic diversity,conserved in cultivated trees and cultivars,has remained *** limits efficient conservation of its diversity as well as efficient use of the existing germplasm *** we performed genotyping-by-sequencing(GBS)on 102 cultivated germplasms of ginkgo collected to explore their genetic structure,kinship,and inbreeding *** the first time in ginkgo,a genome-wide association analysis study(GWAS)was used to attempt gene mapping of seed *** results showed that most of the germplasms did not show any obvious genetic *** size of the ginkgo germplasm population expanded significantly around 1500 years ago during the Sui and Tang *** of seed cultivars based on a phylogenetic perspective does not support the current classification criteria based on ***-four candidate genes were localized after performing GWAS on the seed ***,this study reveals the genetic basis of ginkgo seed traits and provides insights into its cultivation *** findings will facilitate the conservation and utilization of the domesticated germplasms of this living fossil plant.

关键词： cultivar likely expanded

Structural and compositional analysis of(InGa)(AsSb)/GaAs/GaP Stranski-Krastanov quantum dots

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2021年第7期10卷 1313-1325页

作者： Raja S.R.Gajjela Arthur L.Hendriks James O.Douglas Elisa M.Sala petr Steindl petr Klenovský Paul A.J.Bagot Michael P.Moody Dieter Bimberg Paul M.Koenraad Department of Applied Physics Eindhoven University of Technology5612 AZ EindhovenThe Netherlands Department of Materials University of OxfordParks RoadOxford OX13PHUK Center for Nanophotonics Institute for Solid State PhysicsTechnischeUniversität BerlinHardenbergstr.3610623 BerlinGermany EPSRC National Epitaxy Facility The University of SheffieldNorth CampusBroad LaneSheffield S37HQUK Department of Condensed Matter Physics Faculty of ScienceMasaryk UniversityKotlářská267/261137 BrnoCzech Republic Huygens-Kamerlingh Onnes Laboratory Leiden UniversityP.O.Box 95042300 RA LeidenNetherlands Czech Metrology Institute Okružní3163800 BrnoCzech Republic “Bimberg Chinese-German Center for Green Photonics”Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Sciences at CIOMP13033 ChangchunChina

We investigated metal-organic vapor phase epitaxy grown(InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots(QDs)with potential applications in QD-Flash memories by cross-sectional scanning tunneling microscopy(X-STM)and atom probe tomography(APT).The combination of X-STM and APT is a very powerful approach to study semiconductor heterostructures with atomic resolution,which provides detailed structural and compositional information on the *** rather small QDs are found to be of truncated pyramid shape with a very small top facet and occur in our sample with a very high density of∼4×10^(11) cm^(−2).APT experiments revealed that the QDs are GaAs rich with smaller amounts of In and *** element(FE)simulations are performed using structural data from X-STM to calculate the lattice constant and the outward relaxation of the cleaved *** composition of the QDs is estimated by combining the results from X-STM and the FE simulations,yielding∼In_(x)Ga_(1−x)As_(1−y)Sb_(y),where x=0.25–0.30 and y=0.10–***,the reported composition is in good agreement with the experimental results obtained by APT,previous optical,electrical,and theoretical analysis carried out on this material *** confirms that the InGaSb and GaAs layers involved in the QD formation have strongly intermixed.A detailed analysis of the QD capping layer shows the segregation of Sb and In from the QD layer,where both APT and X-STM show that the Sb mainly resides outside the QDs proving that Sb has mainly acted as a surfactant during the dot *** structural and compositional analysis provides a valuable insight into this novel QD system and a path for further growth optimization to improve the storage time of the QD-Flash memory devices.

关键词： analysis quantum sectional

A detailed mechanism of degradation behaviour of biodegradable as-ECAPed Zn-0.8Mg-0.2Sr with emphasis on localized corrosion attack

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Bioactive Materials 2023年第9期27卷 447-460页

作者： Jan Pinc Andrea Skolakova Vojtech Hybasek Sarka Msallamova petr Vertat petr Ashcheulov Martin Vondracek Jan Duchon Ingrid McCarroll Matej Hývl Swarnendu Banerjee Jan Drahokoupil Jirí Kubasek Dalibor Vojtech Jaroslav Capek Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2Prague 818221Czech Republic University of Chemistry and Technology Faculty of Chemical TechnologyDepartment of Metals and Corrosion EngineeringTechnicka 516628Praha 6-DejviceCzech Republic Max-Planck-Institut Für Eisenforschung Max-Planck-Straße 140237DüsseldorfGermany

In this study, advanced techniques such as atom probe tomography, atomic force microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy were used to determine the corrosion mechanism of the as-ECAPed Zn-0.8Mg-0.2Sr alloy. The influence of microstructural and surface features on the corrosion mechanism was investigated. Despite its significance, the surface composition before exposure is often neglected by the scientific community. The analyses revealed the formation of thin ZnO, MgO, and MgCO3 layers on the surface of the material before exposure. These layers participated in the formation of corrosion products, leading to the predominant occurrence of hydrozincite. In addition, the layers possessed different resistance to the environment, resulting in localized corrosion attacks. The segregation of Mg on the Zn grain boundaries with lower potential compared with the Zn-matrix was revealed by atom probe tomography and atomic force microscopy. The degradation process was initiated by the activity of micro-galvanic cells, specifically Zn - Mg2Zn11/SrZn13. This process led to the activity of the crevice corrosion mechanism and subsequent attack to a depth of 250 μm. The corrosion rate of the alloy determined by the weight loss method was 0.36 mm⋅a􀀀 1. Based on this detailed study, the degradation mechanism of the Zn-0.8Mg-0.2Sr alloy is proposed.

关键词： Biodegradable metals Zinc-based alloy Characterization Mechanism ECAP