scholarly journals RESEARCH OF THERMAL AND THERMOMECHANICAL PROPERTIES OF COPOLYMERS BASED ON PYROMELLITE DIANHYDRIDE, 4,4'-DIAMINODIPHENYLOXIDE AND [2-(AMINOMETHYL)BICYCLO[2.2.1]HEPT-3-YL]ANILINES

2021 ◽  
pp. 115-118
Author(s):  
I. A. Novakov ◽  
B. S. Orlinson ◽  
R. V. Brunilin ◽  
D. A. Kudryavtseva ◽  
A. A. Solomatina ◽  
...  
Keyword(s):  
Hydrolytic Stability ◽  
Thermomechanical Properties ◽  
Pyromellitic Dianhydride ◽  
Inert Medium ◽  
Aromatic Polyimides ◽  
Thermomechanical Characteristics ◽  
Bicyclic Diamines ◽  
High Level ◽  
First Time

The thermal and thermomechanical properties of copolyimides based on pyromellitic dianhydride, 4,4'-diaminodiphenyloxide and [2-(aminomethyl)bicyclo [2.2.1]hept-3-yl]anilines in an inert medium have been studied for the first time. It is shown that the introduction into the structure of aromatic polyimides up to 20 mol %. asymmetric vicinally substituted bicyclic diamines allows to obtain materials with increased hydrolytic stability in comparison with fully aromatic polyimides while maintaining a high level of thermomechanical characteristics.

A Confrontation between Two Doctrines: The Birth of Struggle for Hegemony in Hebrew Children's Literature during the 1930s and 1940s

2008 ◽  
Vol 1 (2) ◽  
pp. 139-155 ◽  
Author(s):  
YAEL DARR
Keyword(s):  
Children's Literature ◽  
Educational System ◽  
Single Channel ◽  
Children’S Literature ◽  
The Political ◽  
Literary Creation ◽  
History Of ◽  
High Level ◽  
First Time ◽  
Literary Quality

This article describes a crucial and fundamental stage in the transformation of Hebrew children's literature, during the late 1930s and 1940s, from a single channel of expression to a multi-layered polyphony of models and voices. It claims that for the first time in the history of Hebrew children's literature there took place a doctrinal confrontation between two groups of taste-makers. The article outlines the pedagogical and ideological designs of traditionalist Zionist educators, and suggests how these were challenged by a group of prominent writers of adult poetry, members of the Modernist movement. These writers, it is argued, advocated autonomous literary creation, and insisted on a high level of literary quality. Their intervention not only dramatically changed the repertoire of Hebrew children's literature, but also the rules of literary discourse. The article suggests that, through the Modernists’ polemical efforts, Hebrew children's literature was able to free itself from its position as an apparatus controlled by the political-educational system and to become a dynamic and multi-layered field.

scholarly journals Kinetical Study, Thermo-Mechanical Characteristics and Recyclability of Epoxidized Camelina Oil Cured with Antagonist Structure (Aliphatic/Aromatic) or Functionality (Acid/Amine) Hardeners

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2503
Author(s):  
Chiara Di Mauro ◽  
Aratz Genua ◽  
Alice Mija
Keyword(s):  
Disulfide Bonds ◽  
Mechanical Characteristics ◽  
Dicarboxylic Acids ◽  
Thermomechanical Properties ◽  
Chemical Recycling ◽  
Camelina Oil ◽  
Ft Ir ◽  
Tan Δ ◽  
The Individual ◽  
First Time

In an attempt to prepare sustainable epoxy thermosets, this study introduces for the first time the idea to use antagonist structures (aromatic/aliphatic) or functionalities (acid/amine) as hardeners to produce reprocessable resins based on epoxidized camelina oil (ECMO). Two kinds of mixtures were tested: one combines aromatic/aliphatic dicarboxylic acids: 2,2′-dithiodibenzoic acid (DTBA) and 3,3′-dithiodipropionic acid (DTDA); another is the combination of two aromatic structures with acid/amine functionality: DTBA and 4-aminophenyl disulfide (4-AFD). DSC and FT-IR analyses were used as methods to analyze the curing reaction of ECMO with the hardeners. It was found that the thermosets obtained with the dual crosslinked mechanism needed reduced curing temperatures and reprocessing protocols compared to the individual crosslinked thermosets. Thanks to the contribution of disulfide bonds in the network topology, the obtained thermosets showed recycling ability. The final thermomechanical properties of the virgin and mechanical reprocessed materials were analyzed by DMA and TGA. The obtained thermosets range from elastomeric to rigid materials. As an example, the ECMO/DTBA704-AFD30 virgin or reprocessed thermosets have tan δ values reaching 82–83 °C. The study also investigates the chemical recycling and the solvent resistance of these vitrimer-like materials.

scholarly journals Aberrant Expression of TLR2, TLR7, TLR9, Splicing Variants of TLR4 and MYD88 in Chronic Lymphocytic Leukemia Patients

2021 ◽  
Vol 10 (4) ◽  
pp. 867
Author(s):  
Katarzyna Skorka ◽  
Paulina Wlasiuk ◽  
Agnieszka Karczmarczyk ◽  
Krzysztof Giannopoulos
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Cytotoxic T Cells ◽  
Lymphocytic Leukemia ◽  
Aberrant Expression ◽  
Downstream Signaling ◽  
Splicing Variants ◽  
High Level ◽  
Time To First Treatment ◽  
First Time

Functional toll-like receptors (TLRs) could modulate anti-tumor effects by activating inflammatory cytokines and the cytotoxic T-cells response. However, excessive TLR expression could promote tumor progression, since TLR-induced inflammation might stimulate cancer cells expansion into the microenvironment. Myd88 is involved in activation NF-κB through TLRs downstream signaling, hence in the current study we provided, for the first time, a complex characterization of expression of TLR2, TLR4, TLR7, TLR9, and MYD88 as well as their splicing forms in two distinct compartments of the microenvironment of chronic lymphocytic leukemia (CLL): peripheral blood and bone marrow. We found correlations between MYD88 and TLRs expressions in both compartments, indicating their relevant cooperation in CLL. The MYD88 expression was higher in CLL patients compared to healthy volunteers (HVs) (0.1780 vs. 0.128, p < 0.0001). The TLRs expression was aberrant in CLL compared to HVs. Analysis of survival curves revealed a shorter time to first treatment in the group of patients with low level of TLR4(3) expression compared to high level of TLR4(3) expression in bone marrow (13 months vs. 48 months, p = 0.0207). We suggest that TLRs expression is differentially regulated in CLL but is similarly shared between two distinct compartments of the microenvironment.

scholarly journals Revealing the constituents of Egypt’s oldest beer using infrared and mass spectrometry

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mohamed A. Farag ◽  
Moamen M. Elmassry ◽  
Masahiro Baba ◽  
Renée Friedman
Keyword(s):  
Large Scale ◽  
Beer Brewing ◽  
Chemical Signatures ◽  
Chemical Determination ◽  
Materials Used ◽  
High Level ◽  
Beer Production ◽  
First Time ◽  
Detailed Chemical

Abstract Previous studies have shown that the Ancient Egyptians used malted wheat and barley as the main ingredients in beer brewing, but the chemical determination of the exact recipe is still lacking. To investigate the constituents of ancient beer, we conducted a detailed IR and GC-MS based metabolite analyses targeting volatile and non-volatile metabolites on the residues recovered from the interior of vats in what is currently the world’s oldest (c. 3600 BCE) installation for large-scale beer production located at the major pre-pharaonic political center at Hierakonpolis, Egypt. In addition to distinguishing the chemical signatures of various flavoring agents, such as dates, a significant result of our analysis is the finding, for the first time, of phosphoric acid in high level probably used as a preservative much like in modern beverages. This suggests that the early brewers had acquired the knowledge needed to efficiently produce and preserve large quantities of beer. This study provides the most detailed chemical profile of an ancient beer using modern spectrometric techniques and providing evidence for the likely starting materials used in beer brewing.

PREVENTION ISSUES OF OCCUPATIONAL AND PRODUCTION-RELATED DISEASES IN MINING INDUSTRY WORKERS

2021 ◽  
Author(s):  
G.S. Agzamova ◽  
◽  
N.U. Ibragimova ◽  
Yu.A. Abdieva ◽  
Keyword(s):  
Health Care ◽  
Metallurgical Plant ◽  
Occupational Diseases ◽  
Mining Industry ◽  
Production Environment ◽  
Cardiovascular Pathology ◽  
Dynamic Observation ◽  
High Level ◽  
Medical Examinations ◽  
First Time

Abstract: Protecting and promoting the health of workers in the mining industry is one of the most important problems of occupational pathology and health care. The structure and levels of prevention of occupational diseases are directly dependent on harmful and adverse factors of the production environment and labor process, adequately reflecting the state of production. Purpose: to study the issues of prevention of occupational and production-related diseases of mining and metallurgical plant workers. Research materials and methods: a dynamic observation of the health status of workers in the main industries of the mining and metallurgical plant (800 workers) was carried out. 92 patients with silicosis were examined. Results: Up to 92.8% of first-time occupational diseases are detected during periodic medical examinations. The prevailing sociomatic pathology is cardiovascular pathology, namely, arterial hypertension and diseases of the musculoskeletal system, mainly osteochondrosis of the spine. Prevalence of silicosis was observed in individuals with little professional experience (from 5 years old), young age and primary detection of patients in stage II silicosis, which was accompanied by respiratory failure. Conclusions: The prevention programme developed will ensure a high level of health care in terms of early diagnosis, rehabilitation and secondary prevention of both occupational and occupational diseases.

Innovation in Slovenian tourism organisations

2015 ◽  
Vol 21 (1) ◽  
pp. 51-62
Author(s):  
Maja Uran Maravić ◽  
Dejan Križaj ◽  
Miha Lesjak
Keyword(s):  
Design Methodology ◽  
Mean Value ◽  
Sample Survey ◽  
Research Activity ◽  
Main Hypothesis ◽  
Innovation Activities ◽  
Innovation Climate ◽  
High Level ◽  
Innovation Practices ◽  
First Time

The purpose – Slovenian tourism organisations must constantly focus on developing variety innovations for organisations. In this paper, we present a study conducted on innovation practices in Slovenian tourism organisations. Design/methodology – In a survey conducted on Slovenia tourism organisations, we obtained data and identified their innovation performance and the innovation climate in their area of business. There are three main hypothesis tested. Findings – The research sample of 41 organisations found that most innovation in tourism organisations came through the introduction of new services (90%), followed by innovation through new organisational methods (73%), and found a high-level climate for innovation. Worse was its assessment of research activity within organisations and cooperation with external institutions (eg. universities and research institutes) and investment in innovation activities within their research and development. Results obtained from the research showed a mean value for the innovation climate-instrument of 3.83 indicating a high innovation climate for the Slovenian tourism companies included in the sample survey. Mostly, (publicly known as) more innovative active organisations responded to our survey. From such results, we find that tourism organisations included in the survey are aware of the importance of innovation, teaching organisations to communicate well and network with other organisations, are adaptable to change and engaged with their own ideas in support of the organisation's management. Originality of the research – The contribution of the research is that it has applied the generic instrument for measuring innovation climate on tourism and the first time climate is measured in Slovenia.

Theoretical study of the Cl(2P) + SiH4 reaction: Global potential energy surface and product pair-correlated distributions. Comparison with experiment.

2021 ◽  
Author(s):  
J. Espinosa-Garcia ◽  
Jose Carlos Corchado
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Theoretical Study ◽  
Title Reaction ◽  
Comparison With Experiment ◽  
Explicitly Correlated ◽  
High Level ◽  
First Time ◽  
Product Pair

For the theoretical study of the title reaction, an analytical full-dimensional potential energy surface named PES-2021 was developed for the first time, by fitting high-level explicitly-correlated ab initio data. This...

On sinterability of nanostructured W produced by high-energy ball milling

2007 ◽  
Vol 22 (5) ◽  
pp. 1200-1206 ◽  
Author(s):  
R. Malewar ◽  
K.S. Kumar ◽  
B.S. Murty ◽  
B. Sarma ◽  
S.K. Pabi
Keyword(s):  
Sintered Density ◽  
Sintering Temperature ◽  
High Energy ◽  
Deformation Bands ◽  
Dramatic Decrease ◽  
Powder Charge ◽  
Grinding Media ◽  
Energy Ball ◽  
High Level ◽  
First Time

The present investigation reports for the first time a dramatic decrease in the sintering temperature of elemental W from the conventional temperature of ≥2500 °C to the modest temperature range of 1700–1790 °C by making the W powder nanostructured through high-energy mechanical milling (MM) prior to sintering. The crystallite size of the initial W powder charge with a particle size of 3–4 μm could be brought down to 8 nm by MM for 5 h in WC grinding media. Further milling resulted in a high level of WC contamination, which apparently was due to work hardening and the grain refinement of W. A sintered density as high as 97.4% was achieved by sintering cold, isostatically pressed nanocrystalline (8 nm) W powder at 1790 °C for 900 min. The microstructure of the sintered rods showed the presence of deformation bands, but no cracks, within a large number of W grains. The mechanical properties, when compared with the hardness and elastic modulus, of the sintered nano-W specimen were somewhat superior to those reported for the conventional sintered W.

scholarly journals Structure and Stability of Chemically Modified DNA Bases: Quantum Chemical Calculations on 16 Isomers of Diphosphocytosine

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Abdullah G. Al-Sehemi ◽  
Tarek M. El-Gogary ◽  
Karl Peter Wolschann ◽  
Gottfried Koehler
Keyword(s):  
Relative Stability ◽  
Density Functional ◽  
Chemically Modified ◽  
Functional Methods ◽  
Modified Dna ◽  
Polarized Continuum Model ◽  
Stability Order ◽  
High Dielectric ◽  
High Level ◽  
First Time

We studied for the first time 16 tautomers/rotamers of diphosphocytosine by four computational methods. Some of these tautomers/rotamers are isoenergetic although they have different structures. High-level electron correlation MP2 and MP4(SDQ) ab initio methods and density functional methods employing a B3LYP and the new M06-2X functional were used to study the structure and relative stability of 16 tautomers/rotamers of diphosphocytosine. The dienol tautomers of diphosphocytosine are shown to be much more stable than the keto-enol and diketo forms. The tautomers/rotamers stability could be ranked as PC3 = PC12 < PC2 = PC11 < PC1 < PC10 < PC8 < PC9 < PC15 < PC16 < PC6 ~ PC7 < PC13 < PC4 ~ PC14 < PC5. This stability order was discussed in the light of stereo and electronic factors. Solvation effect has been modeled in a high dielectric solvent, water using the polarized continuum model (PCM). Consideration of the solvent causes some reordering of the relative stability of diphosphocytosine tautomers: PC3 ~ PC12 ~ PC2 ~ PC11 < PC1 < PC10 < PC8 < PC9 < PC15 ~ PC16 < PC13 < PC6 ~ PC7 ~ PC14 < PC4 ~ PC5.

scholarly journals The use of differential calculation methods for the destruction of copolymers of polyethylene glycol fumarate with the acrylic acid

2020 ◽  
Vol 99 (3) ◽  
pp. 4-10
Author(s):  
M.Zh. Burkeev ◽  
◽  
A.Zh. Sarsenbekova ◽  
A.N. Bolatbay ◽  
E.M. Tazhbaev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Polyethylene Glycol ◽  
Acrylic Acid ◽  
Polyester Resin ◽  
Thermodynamic Characteristics ◽  
Nitrogen Atmosphere ◽  
Inert Medium ◽  
Good Convergence ◽  
Sample Decomposition ◽  
First Time

In this work, the thermal decomposition of copolymers based on polyethylene glycol fumarate with the acrylic acid using various ratios of initial monomers has been studied for the first time. The samples were studied in air and nitrogen. According to the thermograms analysis, it was found that the copolymer sample decomposition begins at higher temperatures for a copolymer with high content of polyester resin. The copolymer is vigorously oxidized by the oxygen when heated in air, and one can observe almost complete sample decomposition, whereas it decomposes with a residue of ~ 15% in an inert medium. The activation energies for copolymers with different compositions were estimated using the differential methods of Freeman-Carroll, Achar and Sharpe-Wentworth. The activation energy values found by the three methods demonstrated a good convergence. It was shown that, the activation energy values are higher (~ 200 kJ/mol in the inert medium, and ~ 95 kJ/mol in the oxygen atmosphere) for a copolymer with a lower composition of polyester resin, and the activation energy is ~180 and ~85 kJ/mol for a copolymer with a greater composition of p-EGF-AA. The copolymer is more thermostable in the nitrogen atmosphere according to the kinetic parameters. Additionally, there were determined the thermodynamic characteristics, such as the Gibbs energy (∆G) and the entropy (∆S). They also confirm the destruction process dependence on the components ratio in the synthesized copolymer.

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