1,426 research outputs found

    Mechanical and Electrical Properties of Thin Metal Films Deposited by Vacuum Evaporation

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    Tenké vrstvy mají velké uplatnění v mnoha odvětvích techniky a v současné době můžeme konstatovat, že je najdeme ve všech moderních technologiích. Tenké vrstvy je možné vytvářet dvěma způsoby, a to chemickou nebo fyzikální cestou. Tato práce se zaměřuje na druhý uvedený způsob, přesněji tedy na technologii napařování tenkých vrstev ve vakuu. Práce se zaměřuje na principy procesu, jevy během napařování a po něm. V práci jsou uvedeny originální měření a technologické postupy. Experimenty objasňují některé z jevů, které se odehrávají na tenkých vrstvách vytvořených již zmíněnou technologií. Práce pomáhá lépe pochopit pochody během vytváření tenké vrstvy a vlastnosti, které ovlivňují kvalitu a stabilitu tenkých vrstev. V závěru jsou popsány výsledky experimentů a jsou zde také shrnuty nové poznatky v oblasti nanášení tenkých vrstev pomocí napařování ve vakuu.Thin layers are widely used in many fields of technology and today we can say that they are found in all modern technologies. Thin layers can be created in two ways, namely by chemical or physical means. This work focuses on the latter method, more particularly a technology of thermal evaporation of thin layers in a vacuum. The work focuses on the process principles during and after the evaporation. Much of the work focuses on the development and design of experiments. These experiments illustrate some of the phenomena that take place on thin films produced by the aforementioned technology. Work helps to better understand processes during formation of thin layers and properties that influence the quality and stability of thin films. In conclusion we describe results of experiments and new developments in the field of thin films deposition using evaporation under vakuum are summarized.

    Ring opening polymerization of lactides and lactones by multimetallic alkyl zinc complexes derived from the acids Ph₂C(X)CO₂2H (X = OH, NH₂ )

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    The reaction of the dialkylzinc reagents R₂Zn with the acids 2,2-Ph₂C(X)(CO₂H), where X = NH₂, OH, i.e. 2,2′-diphenylglycine (dpgH) or benzilic acid (benzH2), in toluene at reflux temperature afforded the tetra-nuclear ring complexes [RZn(dpg)]₄, where R = Me (1), Et (2), 2-CF₃C₆H₄ (3), and 2,4,6-F₃C₆H₂ (4); complex 2 has been previously reported. The crystal structures of 1·(2MeCN), 3 and 4·(4(C₇H₈)·1.59(H₂O)) are reported, along with that of the intermediate compound (2-CF₃C₆H₄)3B·MeCN and the known compound [ZnCl₂(NCMe)₂]. Complexes 1–4, together with the known complex [(ZnEt)₃(ZnL)₃(benz)₃] (5; L = MeCN), have been screened, in the absence of benzyl alcohol, for their potential to act as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL) and rac-lactide (rac-LA); the co-polymerization of ε-CL with rac-LA was also studied. Complexes 3 and 4 bearing fluorinated aryls at zinc were found to afford the highest activities

    Multimetallic lithium complexes derived from the acids Ph₂C(X)CO₂H (X = OH, NH₂) : synthesis, structure and ring opening polymerization of lactides and lactones

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    Reaction of LiOR (R=t-Bu, Ph) with the acids 2,2/-Ph₂C(X)(CO₂H), X=OH (benzH), NH₂ (dpgH) was investigated. For benzH, one equivalent LiOt-Bu in THF afforded [Li(benz)]2⋅2THF (1⋅2THF), which adopts a 1D chain structure. If acetonitrile is used (mild conditions), another polymorph of 1 is isolated; LiOPh also led to 1. Robust work-up afforded [Li₇(benz)₇(MeCN)] 2MeCN THF (2⋅2MeCN⋅THF). Use of LiOt-Bu (2 equivalents) led to {Li₈(Ot-Bu)₂[(benz)](OCPh₂CO₂CPh₂CO2t-Bu)₂(THF)₄} (3), the core of which comprises two open cubes linked by benz ligands. For dpgH, two equivalents of LiOt-Bu in THF afforded [Li6(Ot-Bu)₂(dpg)₂(THF)₂] (4), which contains an Li₂Ov 6-step ladder. Similar reaction of LiOPh afforded [Li₈(PhO)₄(dpg)₄(MeCN)₄] (5). Complexes 1–5 were screened for their potential as catalysts for ring opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL), rac-lactide (rac-LA) and δ-valerolactone (δ-VL). For ROP of ϵ-CL, conversions > 70 % were achievable at 110 °C with good control. For rac-LA and δ-VL, temperatures of at least 110 °C over 12 h were necessary for activity (conversions > 60 %). Systems employing 2 were inactiv

    Determination of the Protonation Constants of Some 4-(Substituted benzylamino)-4,5-dihydro- 1H-1,2,4-triazol-5-ones by the Potentiometric Method in Ethanol–Water Mixtures

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    To gain more information about the effect of solvent on 4,5-dihydro-1H-1,2,4-triazol-5-ones, the stoichiometric protonation constants of thirteen triazoles in ethanol–water mixtures were determined at an ionic strength of 0.10MNaCl and at 25.0±0.1 °C under nitrogen atmosphere. A potentiometric method was used and the  calculation was carried out using the PKAS computer program. The correspondingpKa values of these triazoles were determined in ethanol–water mixtures. Thus, the effects of solvent and molecular structure upon acidity were investigated. The logarithm of the protonation constants of the title 4,5-dihydro- 1H-1,2,4-triazol-5-ones decreased linearly with increasing ethanol content, but the values determined with 80% ethanol did not follow this linear trend. The variation of these constants is discussed on the basis of specific solute–solvent  interactions.KEYWORDS: Potentiometry, protonation constants, solvent effect, triazoles

    Pengaruh Audit Tenure, Audit Delay, Opini Audit Tahun Sebelumnya dan Opinion Shopping terhadap Penerimaan Opini Audit Going Concern pada Perusahaan Manufaktur yang Terdaftar di Bursa Efek Indonesia Tahun 2013-2015

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    The Purpose of this research is to know the influence of audit tenure, audit delay, prior opinion, and opinion shopping to the going concern opinion at manufacturing companies registered in BEI with simultaneously as well as partial relation. The population is manufacturing company listed in BEI in 2013 to 2015 with sample method used that is Purposive Sampling. Analytical techniques used in this research is analysis of logistic regression. The results of this research are partially variable there are audit tenure and opinion shopping are affect the going concern opinion. Variable audit delay and prior opinion have no effect on the going concern opinion. While in the simultaneously relation, the entire research was influential variables are significantly to the going concern opinion

    Isolation and Characterization of Phage Specific to E. Coli O157:H7

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    . Phage therapy is not new because it has been practiced since the early 1900s to cure diseases such as shigellosis, typhus and dysentery that caused by bacteria. However, when antibiotics were discovered in 1941, this antibacterial therapy was quickly abandoned by most western scientists. Antibiotic treatment is usually prescribed to treat pathogenic bacteria E. coliO157:H7. However, since 1950s, the widespread resistance to antibiotics has raised public concern on development of alternatives to antibiotics. As a result of this resistance, there becomes a need for an alternative treatment to work synergistically with antibiotic to deal with bacterial infections. This has led to a new approach by the use of bacteriophage which is phage therapy. Once again, this treatment has received attention as an alternative method against bacterial infection. Phage therapy is the treatment on pathogenic bacterial infections by using bacteriophage which capable of invading bacterial cells and disrupting bacterial metabolism before lysing it. Phages are extremely host-specific and the natural enemies of bacteria. It soon becomes clear that there are huge numbers of bacteriophages existed and waiting to be isolated. Phage specific to E. coliO157:H7 was successfully isolated from sewage treatment sample. The appearance of plaques on lawn of E. coliO157:H7 plate indicates phage capabilities to infect and lyses the host cells. The isolated phage was further characterized based on its morphology, genomic profile, physicochemical attributes, and host specificity to assess their potentials to be developed as phage therapy against E. coliO157:H7

    Role of primary care pharmacists in the post-hospital discharge care of patients: a scoping review protocol

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    \ua9 2022, The Author(s). Background: Evidence has shown that there is a significant problem with medication safety when patients are transferred between settings. The role of community pharmacists and hospital pharmacists in facilitating transition of care has been well-researched. However, with the developing role of pharmacists in general practice as part of a multi-disciplinary team, little is known about their role in improving transition of care when patients move from secondary to primary care. The key objective of this scoping review is to understand the nature and extent of the role of primary care pharmacists for patients recently discharged from secondary care. Methods: This scoping review will follow the Joanna Briggs Institute (JBI) methodology for scoping review underpinned by the Arksey and O’Malley methodology and reported in accordance with the Preferred Reporting Items for Systematic Reviews Extension for Scoping Reviews (PRISMA-ScR) guidelines. The following electronic databases will be systematically searched: MEDLINE, EMBASE, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science and NICE Evidence. Reference lists of included full texts will be searched for relevant papers, in addition to grey literature which includes websites of relevant professional organisations. Primary studies, published in the English language that involved a primary care pharmacist-led intervention post-hospital discharge will be included. Two independent reviewers will screen studies against eligibility criteria and use a piloted data extraction form to extract data related to the review questions. The data will be presented in tabular form and assessed for key themes to identify gaps and inform future research. Discussion: This scoping review will map current evidence surrounding the role of primary care pharmacists in the post-hospital discharge care of patients. Findings will inform ongoing research to support safer transfer-of-care post-hospital discharge and identify ways in which collaboration between healthcare professionals can be improved. This review anticipates guiding the inclusion of patient and public involvement (PPI) at the consultation stage to validate and build on the findings

    Penilaian Kinerja Lingkungan pada Proyek Konstruksi

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    Industri konstruksi menimbulkan dampak negatif terhadap lingkungan disebabkan oleh meningkatnya volume limbah yang dihasilkan oleh aktivitas konstruksi itu sendiri. Berbagai literatur menunjukkan bahwa upaya mengurangi limbah (reducing waste) menjadi sangat penting untuk dilakukan di semua tahapan kontruksi karena sampai saat ini masih menjadi cara terbaik dalam pengelolaan dan penanganan limbah. Penelitian yang ada di seluruh dunia telah banyak mengevaluasi berbagai dampak limbah dan energi yang ditimbulkan selama kegiatan kontruksi. Paper ini membahas tentang berbagai model penilaiaan (assessment) kinerja lingkungan dari suatu penelitian sebelumnya yang telah digunakan secara Internasional. Dan paper ini menyajikan kajian kritis dari metode terbaru dalam penilaian kinerja lingkungan dari proyek-proyek konstruksi. Metode yang digunakan untuk mengukur kinerja lingkungan antara lain: Contractor’s Environmental Performance Scoring System (C-EPSS), Environmental Performance Assessment (EPA), Building Waste Assessment Score (BWAS) Waste Management Performance Evaluation Tool (WMPET) dan Environmental Performance Score (EPS)

    The Effect of STEM Curriculum Based on Islamic Perspective on 9th Grade Talented Female Students' Critical Thinking in Gaza

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    The study aimed to uncover the effect of using a Developed Science Curriculum Based on STEM approach with Islamic Perspective on Improving Critical Thinking Skills among 9th Grade Talented female students in Gaza. To achieve the study objectives, the two researchers analyzed the content "Human body organs" in science course to the ninth grade in the light of critical thinking skills, as its shown that critical thinking skills which are available in the unit are conclusion, deduction, interpretation, Arguments evaluation, and hypotheses. The researchers used the quasi-experimental approach. The study used critical thinking skills test as tool. The study was conducted on 21 female 9th grade talented students in west Gaza Directorate. Results of the study showed statistically significant differences at significance level (α = 0.01) between the average scores of the critical thinking skills of the experimental group in the pre/post application of critical thinking skills test. In addition, the results showed differences in the post application in all critical thinking skills, and that thea Developed Science Curriculum Based on STEM approach with Islamic Perspective has a significant impact (ƞ² = 0.61)
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