bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Characterization of Polysaccharide Composite Films from Polyion Complex Particles
Authors: Yamazaki Makoto , Iijima Kazutoshi
Published: February 2020

Biomaterials made of natural polysaccharides have attracted much attention due to the fact of their excellent properties, such as high biocompatibility and biodegradability, and their specific biological functions based on their chemical structures. This study demonstrates that polysaccharide composite films can be fabricated from polyion complexes (PICs) with their particles used as building components. Dispersion of PIC particles prepared by mixing, centrifugation, and re-dispersion of dilute solutions of cationic and anionic polysaccharides were cast, dried, and formed into films several micrometers thick. These films were homogenous and water insoluble. It was revealed that the component anionic polysaccharides affected the film’s properties such as the swelling behavior and mechanical characteristics. Adhesion of NIH3T3 cells (integrin: high, CD44: lack or weak) and A549 cells (integrin: high, CD44: high) to the composite films were examined. Both NIH3T3 and A549 cells adhered to heparin/chitosan (HEP/CHI) film because HEP has an affinity for integrin through fibronectin. However, A549 cells adhered to chondroitin sulfate (CS)/CHI and hyaluronic acid (HYA)/CHI films, whereas NIH3T3 cells did not, because both CS and HYA have affinity for CD44. These results indicated that the biological functions of anionic polysaccharides were maintained on the surface of the composite films. It was also possible to fabricate films composed of three kinds of polysaccharides: one cationic polysaccharide and two kinds of anionic polysaccharides. These results show that the properties of films composed of three kinds of polysaccharides may be controllable depending on the anionic polysaccharide composition rates.
Covalent Surface Functionalization of Bovine Serum Albumin to Magnesium Surface to Provide Robust Corrosion Inhibition and Enhance In Vitro Osteo-Inductivity
Authors: Lee Seo Yeon , Shrestha Sita , Shrestha Bishnu Kumar , Park Chan Hee , Kim Cheol Sang
Published: February 2020

Herein, we describe precisely a covalent modification of pure magnesium (Mg) surface and its application to induce in vitro osteogenic differentiation. The new concept of a chemical bonding method is proposed for developing stable chemical bonds on the Mg surface through the serial assembly of bioactive additives that include ascorbic acid (AA) and bovine serum albumin (BSA). We studied both the physicochemical and electrochemical properties using scanning electron microscopy and other techniques to confirm how the covalent bonding of BSA on Mg can, after coating, significantly enhance the chemical stability of the substrate. The modified Mg-OH-AA-BSA exhibits better anti-corrosion behavior with high corrosion potential (Ecorr = −0.96 V) and low corrosion current density (Icorr = 0.2 µA cm−2) as compared to the pure Mg (Ecorr = −1.46 V, Icorr = 10.42 µA cm−2). The outer layer of BSA on Mg protects the fast degradation rate of Mg, which is the consequence of the strong chemicals bonds between amine groups on BSA with carboxylic groups on AA as the possible mechanism of peptide bonds. Collectively, the results suggest that the surface-modified Mg provides a strong bio-interface, and enhances the proliferation and differentiation of pre-osteoblast (MC3T3-E1) cells through a protein–lipid interaction. We therefore conclude that the technique we describe provides a cost-effective and scalable way to generate chemically stable Mg surface that inherits a biological advantage in orthopedic and dental implants in clinical applications.
Effect of Donor-Acceptor Concentration Ratios on Non-Radiative Energy Transfer in Zero-Dimensional Cs4PbBr6 Perovskite/MEH-PPV Nanocomposite Thin Films
Authors: Al-Asbahi Bandar Ali , Qaid Saif M. H. , Aldwayyan Abdullah S.
Published: February 2020

Composite materials with different concentration ratios of a hybrid of zero-dimensional (0-D) Cs4PbBr6 perovskite, which acts as a donor (D), and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), which acts as an acceptor (A), were successfully prepared via a solution blending method prior to being deposited onto glass substrates by a spin-coating technique. The influence of acceptor content on the structural, optical, and energy transfer properties of the donor was investigated. The perovskite nanocrystals formed thin films without any chemical interactions within a matrix of MEH-PPV in the blend. The possibility of dipole–dipole (non-radiative) energy transfer from the 0-D Cs4PbBr6 to the MEH-PPV was proven. The energy transfer parameters such as Ro (critical distance of the energy transfer), kapp (apparent quenching constant), ∅ D A (quantum yield of D in the presence of A), τ D A (lifetime of D in the presence of A), PDA (probability of energy transfer), η (efficiency of energy transfer), RDA (energy transfer radius), kET (energy transfer rate constant), TDR (total decay rate), Ao (critical concentration of A), and Aπ (conjugation length) were calculated based on the absorption and emission measurements.
Integration of Polylactide into Polyethylenimine Facilitates the Safe and Effective Intracellular siRNA Delivery
Authors: Ding Guo-Bin , Meng Xue , Yang Peng , Li Binchun , Stauber Roland H , Li Zhuoyu
Published: February 2020

Polyethylenimine (PEI) is a gold standard polymer with excellent transfection efficacy, yet its severe toxicity and nondegradability hinders its therapeutic application as a gene delivery vector. To tackle this problem, herein we incorporated the biodegradable polylactide (PLA) into the branched PEI by synthesizing a PEI-PLA copolymer via a facile synthetic route. PLA modification significantly improved the cytocompatibility of PEI, PEI-PLA copolymer showed much higher cell viability than PEI as verified in three different human cancer cell lines (HCT116, HepG2 and SKOV3). Interestingly, the PEI-PLA copolymer could effectively bind siRNA targeting PKM2, and the obtained polyplex displayed much higher stability in serum than naked siRNA as determined by agarose gel electrophoresis. Moreover, cellular uptake study demonstrated that PEI-PLA could efficiently deliver the Cy5-labled siRNA into the three tested cancer cell lines, and the transfection efficiency is equivalent to the commercial Lipofectamine® 2000. Finally, it is noteworthy that the polyplex is comparable to Lipo2000 in down-regulating the expression of PKM2 at both mRNA and protein level as measured by q-PCR and western blotting, respectively. Overall, the PEI-PLA copolymer developed in this study has the potential to be developed as a versatile carrier for safe and effective delivery of other nucleic acid-based agents.
High-Conductivity, Flexible and Transparent PEDOT:PSS Electrodes for High Performance Semi-Transparent Supercapacitors
Authors: Song Jiaxing , Ma Guoqiang , Qin Fei , Hu Lin , Luo Bangwu , Liu Tiefeng , Yin Xinxing , Su Zhen , Zeng Zhaobing , Jiang Youyu , Wang Guannan , Li Zaifang
Published: February 2020

Herein, we report a flexible high-conductivity transparent electrode (denoted as S-PH1000), based on conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), and itsapplication to flexible semi-transparentsupercapacitors. A high conductivity of 2673 S/cm was achieved for the S-PH1000 electrode on flexible plastic substrates via a H2SO4 treatment with an optimized concentration of 80 wt.%. This is among the top electrical conductivities of PEDOT:PSS films processed on flexible substrates. As for the electrochemical properties,a high specific capacitance of 161F/g was obtained from the S-PH1000 electrode at a current density of 1 A/g. Excitingly, a specific capacitance of 121 F/g was retained even when the current density increased to 100 A/g, which demonstrates the high-rate property of this electrode. Flexible semi-transparent supercapacitors based on these electrodes demonstrate high transparency, over 60%, at 550 nm. A high power density value, over 19,200 W/kg,and energy density, over 3.40 Wh/kg, was achieved. The semi-transparent flexible supercapacitor was successfully applied topower a light-emitting diode.
Effect of Na2CO3 on the Microstructure and Macroscopic Properties and Mechanism Analysis of PVA/CMC Composite Film
Authors: Zhu Jufang , Li Qiuying , Che Yanchao , Liu Xingchen , Dong Chengcheng , Chen Xinyu , Wang Chao
Published: February 2020

Polyvinyl alcohol (PVA)/carboxyl methyl cellulose sodium (CMC)/Na2CO3 composite films with different contents of Na2CO3 were prepared by blending and solution-casting. The effect of Na2CO3 on the microstructure of PVA/CMC composite film was analyzed by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and atomic force microscopy (AFM). Its macroscopic properties were analyzed by water sorption, solubility, and dielectric constant tests. The results show that the microstructure of PVA/CMC/Na2CO3 composite films was different from that of PVA and PVA/CMC composite films. In addition, compared to PVA and PVA/CMC composite films, the water sorption of PVA/CMC/Na2CO3 composite films relatively increased, the solubility in water significantly decreased, and the dielectric properties significantly improved. All these results indicate that the hydrogen bonding interaction between PVA and CMC increased and the crystallinity of PVA decreased after the addition of Na2CO3. This was also a direct factor leading to increased water sorption, decreased solubility, and enhanced dielectric properties. The reaction mechanism of PVA, CMC, and Na2CO3 is proposed to further evaluate the effect of Na2CO3 on the microstructure and macroscopic properties of PVA/CMC/Na2CO3 composite films.
Dentin Bonding and SEM Analysis of a New Experimental Universal Adhesive System Containing a Dendrimer
Authors: Vasconcelos e Cruz Joana , Polido Mário , Brito José , Gonçalves Luisa L.
Published: February 2020

Due to their polymerization characteristics, hyper-branched dendrimers have lately shown to be promising candidates for use in dental materials. In this study, a new dental adhesive system was prepared, using a dendrimer derived from 2-isocyanatoethyl methacrylate (G-IEMA), and its adhesive properties were investigated. The exposed dentin was treated with four universal adhesives (UAs): SBU (Scotchbond Universal™), FUT (Futurabond M+™), AE1 (experimental adhesive with Bis-GMA) and AE2 (experimental adhesive with G-IEMA), using Etch & Rinse (ER) or Self Etch (SE) protocols. Composite build-ups were prepared and stored for 24 h at 37 °C in distilled water. Composite/dentin beams were prepared with cross-sectional areas of 1 ± 0.3 mm2 and µTBS (Micro-tensile bond strength) test was performed at 0.5 mm/min. Failures modes were evaluated by stereomicroscopy, and bonding interfaces were observed by scanning electron microscopy (SEM). Statistical analysis of µTBS data was performed using General Linear (GLM) and Linear Mixed Models (LMM). The effect of adhesive type on µTBS was significant (p = 0.010), with AE1 presenting significantly higher µTBS than SBU (p = 0.019). No other differences between adhesives were observed. ER showed significantly better results than SE (p = 0.019), and no significant interactions between the adhesives and protocols were determined. Results obtained so far pinpoint the emergence of a new paradigm in the dental materials field, as G-IEMA can be used successfully as an alternative to Bis-GMA.
Development of Poly (Lactide Acid) Foams with Thermally Expandable Microspheres
Authors: Kmetty Ákos , Litauszki Katalin
Published: February 2020

This study presents the investigation of different content of thermally expandable microsphere (EMS) type of a physical blowing agent added to polylactic acid (PLA). The effects of the different doses of EMS, processing temperatures, and d-lactide content of the polylactic acid were analyzed for foam properties and structures. We characterized the different PLAs and the physical blowing agent with different testing methods (gel permeation chromatography, rotational rheometry, isothermal thermogravimetric analysis, and thermomechanical analysis). The amounts of the foaming agent were 0.5, 1, 2, 4, 8 wt%, and processing temperatures were 190 °C, 210 °C, and 230 °C. The foam structures were produced by twin-screw extrusion. We used scanning electron microscopy to examine the cell structure of the foams produced, and carried out morphological and mechanical tests as well. The result of extrusion foaming of PLA using different amounts of EMS shows that an exponentially decreasing tendency of density reduction can be achieved, described by the following equation, ρ(x ) = 1.062 · e − x 7.038 + 0.03 (R2 = 0.947) at 190 °C. With increasing processing temperature, density decreases at a lower rate, due to the effect that the microspheres are unable to hold the pentane gas within the polymer shell structure. The d-lactide content of the PLAs does not have a significant effect on the density of the produced foam structures.
On the Nature of Epoxy Resin Post-Curing
Authors: Moller James C. , Berry Rajiv J. , Foster Heather A.
Published: February 2020

Post-curing is intended to improve strength, elevate glass transition, and reduce residual stress and outgassing in thermosets. Also, experiments indicate post-curing temperatures lead to ether crosslinks and backbone dehydration. These results informed molecular dynamics methods to represent them and compare the resulting thermomechanical effects. Diglycidyl ether of bisphenol A (DGEBA)-diamino diphenyl sulfone (DDS) systems were examined. Independent variables were resin length, stoichiometry, and reaction type (i.e., amine addition, etherification, and dehydration). Etherification affected excess epoxide systems most. These were strengthened and became strain hardening. Systems which were both etherified and dehydrated were most consistent with results of post-curing experiments. Dehydration stiffened and strengthened systems with the longer resin molecules due to their intermediate hydroxyl groups for crosslinking. Changes in the concavity of functions fit to the specific volume versus temperature were used to detect thermal transitions. Etherification generally increased transition temperatures. Dehydration resulted in more transitions.
Methods for Determining the Thermal Transfer in Phase-Changing Materials (PCMs)
Authors: Bendic Vasile , Dobrotă Dan , Simion Ionel , Bălan Emilia , Pascu Nicoleta-Elisabeta , Tilina Dana Iuliana
Published: February 2020

A very important issue that needs to be solved as simply and correctly as possible is how to establish the thermal performance of phase-changing materials (PCM). The undertaken researches have analyzed the values of the thermal performances of the PCM taking into account the method of finite elements and the experimental research, respectively, based on a modern measurement system that was designed and implemented. Butyl stearate which has been encapsulated through complex coacervation in polymethyl methacrylate has been used as a PCM. Samples were made containing 10%, 20%, 30% and 40% PCM, respectively, within their structure. The research has established that at both the hot plate and the cold plate interface, the evolution of the temperature over time, established by both the finite element method (FEM) and experimental research, are quite close, and the best results have been obtained for the P30 sample. A very important thing observed during the finite element method (FEM) is that the simulated thermal flow variation extends between 2700-3110W/m2 being small enough not to influence the temperature measurement at the interface of hot or cold plates. Thus, the use of the FEM or the experimental research method can be applied with good results, provided that the correct initial conditions are used in the finite element method and that the experimental research is performed using the best possible apparatus.
Supramolecular Triblock Copolymers Through the Formation of Hydrogen Bonds: Synthesis, Characterization, Association Effects in Solvents of Different Polarity
Authors: Bitsi Spyridoula-Lida , Droulia Margarita , Pitsikalis Marinos
Published: February 2020

Anionic polymerization techniques were employed for the synthesis of linear polystyrene (PS) and block copolymer of PS and polyisoprene (PI) PS-b-PI bearing end hydroxyl groups. Following suitable organic chemistry transformation, the –OH end groups were converted to moieties able to form complementary hydrogen bonds including 2,6-diaminopurine, Dap, thymine, Thy, and the so-called Hamilton receptor, Ham. The formation of hydrogen bonds was examined between the polymers PS-Dap and PS-b-PI-Thy, along with the polymers PS-Ham and PS-b-PI-Thy. The conditions under which supramolecular triblock copolymers are formed and the possibility to form aggregates were examined both in solution and in the solid state using a variety of techniques such as 1H-NMR spectroscopy, size exclusion chromatography (SEC), dilute solution viscometry, dynamic light scattering (DLS), thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC).
The Performance Changes and Migration Behavior of PLA/Nano-TiO2 Composite Film by High-Pressure Treatment in Ethanol Solution
Authors: Tang Zhenya , Fan Fangling , Fan Chunli , Jiang Kai , Qin Yuyue
Published: February 2020

To study the relationship between performance changes and nanoparticles migration of the composite film at different migration stages, the poly (lactic acid) (PLA)/nano-TiO2 composite film treated by high pressure was immersed in 50% (v/v) ethanol solution for 45 days at 40 °C, and the film characteristics and migration behavior were analyzed. The results showed that the migration of the composite film with the highest loading of nano-TiO2 (20 wt. %) in alcoholic food simulated solution was far less than 10 mg/kg during the 45-day migration process. Although with the increase of migration time, the micro-morphology of composite film became rougher, the crystallinity decreased and the gas permeability increased, but the internal crystal structure of the composite film remained basically unchanged. The PLA/nano-TiO2 composite films treated by high pressure treatment were relatively stable, and had good performance and migration behavior in alcoholic food simulated solution, the nanocomposite film after high pressure treatment could be used to reduce nano-TiO2 particle migration and subsequently reduce human exposure as the packaging film for the packaging of alcoholic food, which provide a theoretical basis for the applications of high pressure treatment of PLA/nano-TiO2 composite films in food packaging material and broaden its application prospects.
Development of Interfacial Adhesive Property by Novel Anti-Stripping Composite between Acidic Aggregate and Asphalt
Authors: Zhang Guohong , Qiu Jianhui , Zhao Jingzhuo , Wei Dingbang , Wang Hui
Published: February 2020

Studies on control of and preventive measures against asphalt pavement moisture damage have important economic and social significance due to the multiple damage and repair of pavements, the reasons for which include the poor interfacial adhesive ability between acidic aggregates and asphalts. Anti-stripping agent is used in order to improve the poor adhesion, and decomposition temperature is regarded as being important for lots of anti-stripping products, because they always decompose and lose their abilities under the high temperature in the mixing plant before application to the pavement. A novel anti-stripping composite, montmorillonoid/Polyamide (OMMT/PAR), which possesses excellent thermal stability performance and is effective in preventing moisture damage, especially for acidic aggregates, was prepared. Moreover, the modification mechanisms and pavement properties were also investigated with reference to the composites. The results show that OMMT/PAR was prepared successfully, improving the interfacial adhesion between the acidic aggregate and the modified asphalt. Due to the nanostructure of OMMT/PAR, the thermal stability was enhanced dramatically and the interfacial adhesion properties were also improved. Furthermore, asphalts modified with OMMT/PAR and their mixtures showed excellent properties. Finally, the moisture damage process and the mechanisms by which OMMT/PAR improves the interfacial adhesion properties are explained through adhesion mechanism analyses.
Effect of PEW and CS on the Thermal, Mechanical, and Shape Memory Properties of UHMWPE
Authors: Zhang Run , Wang Suwei , Tian Jing , Chen Ke , Xue Ping , Wu Yihui , Chou Weimin
Published: February 2020

Modified ultra-high-molecular-weight polyethylene (UHMWPE) with calcium stearate (CS) and polyethylene wax (PEW) is a feasible method to improve the fluidity of materials because of the tense entanglement network formed by the extremely long molecular chains of UHMWPE, and a modified UHMWPE sheet was fabricated by compression molding technology. A Fourier-transform infrared spectroscopy test found that a new chemical bond was generated at 1097 cm−1 in the materials. Besides, further tests on the thermal, thermomechanical, mechanical, and shape memory properties of the samples were also conducted, which indicates that all properties are affected by the dimension and distribution of crystal regions. Moreover, the experimental results indicate that the addition of PEW and CS can effectively improve the mechanical properties. Additionally, the best comprehensive performance of the samples was obtained at the PEW content of 5 wt % and the CS content of 1 wt %. In addition, the effect of temperature on the shape memory properties of the samples was investigated, and the results indicate that the shape fixity ratio (Rf) and the shape recovery ratio (Rr) can reach 100% at 115 °C and 79% at 100 °C, respectively, which can contribute to the development of UHMWPE-based shape memory polymers.
Structural Changes of Oak Wood Main Components Caused by Thermal Modification
Authors: Kubovský Ivan , Kačíková Danica , Kačík František
Published: February 2020

Thermal modification of wood causes chemical changes that significantly affect the physical, mechanical and biological properties of wood; thus, it is essential to investigate these changes for better utilization of products. Fourier transform infrared spectroscopy and size exclusion chromatography were used for evaluation of chemical changes at thermal treatment of oak wood. Thermal modification was applied according to Thermowood process at the temperatures of 160, 180 and 210 °C, respectively. The results showed that hemicelluloses are less thermally stable than cellulose. Chains of polysaccharides split to shorter ones leading to a decrease of the degree of polymerization and an increase of polydispersity. At the highest temperature of the treatment (210 °C), also crosslinking reactions take place. At lower temperatures degradation reactions of lignin predominate, higher temperatures cause mainly condensation reactions and a molecular weight increase. Chemical changes in main components of thermally modified wood mainly affect its mechanical properties, which should be considered into account especially when designing various timber constructions.
Effect of Phenolic Resin Oligomer Motion Ability on Energy Dissipation of Poly (Butyl Methacrylate)/Phenolic Resins Composites
Authors: Huang Xing , Chen Songbo , Wan Songhan , Niu Ben , He Xianru , Zhang Rui
Published: February 2020

Poly (butyl methacrylate) (PBMA) was blended with a series of phenolic resins (PR) to study the effect of PR molecular weight on dynamic mechanical properties of PBMA/PR composites. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) found a similar variation of glass transition temperature (Tg). The maximum loss peak (tanδmax) improved in all PBMA/PR blends compared with the pure PBMA. However, tanδmax reduced as the molecular weight increased. This is because PR with higher molecular weight is more rigid in the glass transition zone of blends. The hydrogen bonding between PBMA and PR was characterized by Fourier transform infrared spectroscopy (FTIR). Lower molecular weight PR formed more hydrogen bonds with the matrix and it had weaker temperature dependence. Combined with the results from DMA, we studied how molecular weight affected hydrogen bonding and thus further affected tanδmax.
Effects of Adhesive Coating on the Hygrothermal Aging Performance of Pultruded CFRP Plates
Authors: Hao Xinkai , Xian Guijun , Huang Xiangyu , Xin Meiyin , Shen Haijuan
Published: February 2020

Bonding of carbon fiber reinforced polymer (CFRP) plates to a concrete member is a widely used strengthening method. CFRP plates used in construction degrade due to harsh environmental conditions such as high temperature or alkaline solution seepage from concrete. However, the adhesive between CFRP plates and concrete may have a positive effect on the durability performance of CFRP plates. In this paper, the long-term performance of both naked and adhesive coated CFRP pultruded plates subjected to different-temperature water or alkaline solution (20, 40 and 60 °C) are investigated to evaluate the protective effect of adhesive on CFRP plates. It is found that the adhesive coating can slow the deterioration of mechanical properties especially the tensile properties and fiber-matrix interfacial properties. The water absorption mechanism of CFRP plates was also investigated.
Emerging Developments in the Use of Electrospun Fibers and Membranes for Protective Clothing Applications
Authors: Baji Avinash , Agarwal Komal , Oopath Sruthi Venugopal
Published: February 2020

There has been increased interest to develop protective fabrics and clothing for protecting the wearer from hazards such as chemical, biological, heat, UV, pollutants etc. Protective fabrics have been conventionally developed using a wide variety of techniques. However, these conventional protective fabrics lack breathability. For example, conventional protective fabrics offer good protection against water but have limited ability in removing the water vapor and moisture. Fibers and membranes fabricated using electrospinning have demonstrated tremendous potential to develop protective fabrics and clothing. These fabrics based on electrospun fibers and membranes have the potential to provide thermal comfort to the wearer and protect the wearer from wide variety of environmental hazards. This review highlights the emerging applications of electrospinning for developing such breathable and protective fabrics.
Effects of Zirconium Silicide on the Vulcanization, Mechanical and Ablation Resistance Properties of Ceramifiable Silicone Rubber Composites
Authors: Song Jiuqiang , Huang Zhixiong , Qin Yan , Wang Honghua , Shi Minxian
Published: February 2020

Ceramifiable silicone rubber composites play important roles in the field of thermal protection systems (TPS) for rocket motor cases due to their advantages. Ceramifiable silicone rubber composites filled with different contents of ZrSi2 were prepared in this paper. The fffects of ZrSi2 on the vulcanization, mechanical and ablation resistance properties of the composites were also investigated. The results showed that the introduction of ZrSi2 decreased the vulcanization time of silicone rubber. FTIR spectra showed that ZrSi2 did not participate in reactions of the functional groups of silicone rubber. With the increasing content of ZrSi2, the tensile strength increased first and then decreased. The elongation at break decreased and the permanent deformation increased gradually. The thermal conductivity of the composite increased from 0.553 W/(m·K) to 0.694 W/(m·K) as the content of the ZrSi2 increased from 0 to 40 phr. In addition, the thermal conductivity of the composite decreased with the increase of temperature. Moreover, thermal analysis showed that the addition of ZrSi2 increased the initial decomposition temperature of the composite, but had little effect on the peak decomposition temperature in nitrogen. However, the thermal decomposition temperature of the composite in air was lower than that in nitrogen. The addition of ZrSi2 decreased the linear and mass ablation rate, which improved the ablative resistance of the composite. With the ZrSi2 content of 30 phr, the linear and mass ablation rate were 0.041 mm/s and 0.029 g/s, decreasing by 57.5% and 46.3% compared with the composite without ZrSi2, respectively. Consequently, the ceramifiable silicone rubber composite filled with ZrSi2 is very promising for TPS.
Fluorination Effect for Highly Conjugated Alternating Copolymers Involving Thienylenevinylene-Thiophene-Flanked Benzodithiophene and Benzothiadiazole Subunits in Photovoltaic Application
Authors: An Lili , Huang Yubo , Wang Xu , Liang Zezhou , Li Jianfeng , Tong Junfeng
Published: February 2020

Two two-dimensional (2D) donor–acceptor (D-A) type conjugated polymers (CPs), namely, PBDT-TVT-BT and PBDT-TVT-FBT, in which two ((E)-(4,5-didecylthien-2-yl)vinyl)- 5-thien-2-yl (TVT) side chains were introduced into 4,8-position of benzo[1,2-b:4,5-bʹ]dithiophene (BDT) to synthesize the highly conjugated electron-donating building block BDT-TVT, and benzothiadiazole (BT) and/or 5,6-difluoro-BT as electron-accepting unit, were designed to systematically ascertain the impact of fluorination on thermal stability, optoelectronic property, and photovoltaic performance. Both resultant copolymers exhibited the lower bandgap (1.60 ~ 1.69 eV) and deeper highest occupied molecular orbital energy level (EHOMO, –5.17 ~ –5.37 eV). It was found that the narrowed absorption, deepened EHOMO and weakened aggregation in solid film but had insignificant influence on thermal stability after fluorination in PBDT-TVT-FBT. Accordingly, a PBDT-TVT-FBT-based device yielded 16% increased power conversion efficiency (PCE) from 4.50% to 5.22%, benefited from synergistically elevated VOC, JSC, and FF, which was mainly originated from deepened EHOMO, increased μh, μe, and more balanced μh/μe ratio, higher exciton dissociation probability and improved microstructural morphology of the photoactive layer as a result of incorporating fluorine into the polymer backbone.
Thermodynamic Analysis of Supercritical Carbon Dioxide Cycle for Internal Combustion Engine Waste Heat Recovery
Authors: Yu Wan , Gong Qichao , Gao Dan , Wang Gang , Su Huashan , Li Xiang
Published: February 2020

Waste heat recovery of the internal combustion engine (ICE) has attracted much attention, and the supercritical carbon dioxide (S-CO2) cycle was considered as a promising technology. In this paper, a comparison of four S-CO2 cycles for waste heat recovery from the ICE was presented. Improving the exhaust heat recovery ratio and cycle thermal efficiency were significant to the net output power. A discussion about four different cycles with different design parameters was conducted, along with a thermodynamic performance. The results showed that choosing an appropriate inlet pressure of the compressor could achieve the maximum exhaust heat recovery ratio, and the pressure increased with the rising of the turbine inlet pressure and compressor inlet temperature. The maximum exhaust heat recovery ratio for recuperation and pre-compression of the S-CO2 cycle were achieved at 7.65 Mpa and 5.8 MPa, respectively. For the split-flow recompression cycle, thermal efficiency first increased with the increasing of the split ratio (SR), then decreased with a further increase of the SR, but the exhaust heat recovery ratio showed a sustained downward trend with the increase of the SR. For the split-flow expansion cycle, the optimal SR was 0.43 when the thermal efficiency and exhaust heat recovery ratio achieved the maximum. The highest recovery ratio was 24.75% for the split-flow expansion cycle when the total output power, which is the sum of the ICE power output and turbine mechanical power output, increased 15.3%. The thermal performance of the split-flow expansion cycle was the best compared to the other three cycles.
On Fluid Flow Field Visualization in a Staggered Cavity: A Numerical Result
Authors: Rehman Khalil Ur , Kousar Nabeela , Khan Waqar A. , Fatima Nosheen
Published: February 2020

In this paper we have considered a staggered cavity. It is equipped with purely viscous fluid. The physical design is controlled through mathematical formulation in terms of both the equation of continuity and equation of momentum along with boundary constraints. To be more specific, the Navier-Stokes equations for two dimensional Newtonian fluid flow in staggered enclosure is formulated and solved by well trusted method named finite element method. The novelty is increased by considering the motion of upper and lower walls of staggered cavity case-wise namely, in first case we consider that the upper wall of staggered cavity is moving and rest of walls are kept at zero velocity. In second case we consider that the upper and bottom walls are moving in a parallel way. Lastly, the upper and bottom walls are considered in an antiparallel direction. In all cases the deep analysis is performed and results are proposed by means of contour plots. The velocity components are explained by line graphs as well. The kinetic energy examination is reported for all cases. It is trusted that the findings reported in present pagination well serve as a helping source for the upcoming studies towards fluid flow in an enclosure domains being involved in an industrial areas.
The Policies of Provision of Assistive and Welfare Technology—A Literature Review
Authors: Baudin Katarina , Mullersdorf Maria , Sundstrom Angelina , Gustafsson Christine
Published: February 2020

Background: Due to the increasing ageing population worldwide, humanity is facing global demographic challenges. For many people, their later years are often lived with changed functioning and the need for support in daily living activities. Assistive technology and welfare technology (AT/WT) constitute a partial solution to the demographic challenges. Objectives: The purpose of this literature review is to identify the policy features, such as decision models and guidance for the provision of AT/WT as reported in the current scientific literature. Methods: A literature review with a deductive approach using the structure of the Global Cooperation on Assistive Technology (GATE) model was conducted. The data were searched from the databases: PubMed, Cinahl Plus, and the Web of Science, resulting in nine included articles. Results: The findings are presented according to the structure of the eight domains from the GATE model— policy, assessment, procurement, technology, environment, usability, sustainability and rights— which are further grouped into categories exploring the variations in every domain. Conclusion: The review reveals a nascent and growing interest in the area; however, evidence-based decision models and other guidance on AT/WT are lacking. Recent scholarships and policy reforms can form the basis of stronger guidance to organise complex AT/WT systems, but further and future research is needed.
BUILDING A NON-TRIVIAL ECONOMIC AND MATHEMATICAL MODEL FOR MANAGEMENT OF PRODUCTION ORGANIZATIONS
Authors: Rogulin R.S.
Published: February 2020

The author makes an attempt to generalize (combining, integrating) three linear programming problems known to the theory and practice of managing enterprises in the real sector of the economy. This refers to the «classic» production task, as well as the «organization of employment of means of production» and «placement of centers». The solution to the first problem is a vector of the number of final products produced, which is found taking into account resource constraints and the need to maximize profits. The second task is related to the placement of workers in pairs of different specialties on production lines, provided that none of the lines have duplicate profiles of workers. The third task is to select production points from a previously defined list of possible locations. An integrated goal setting that combines the three specified tasks (problems) into one complex production and transport task (problem) is relevant for any production organizations that intend to develop new markets and must optimize their production plans (for example, for enterprises of the timber processing industry that open new production facilities).
According to the author, the generalizing linear mixed-integer model can provide a solution to this complex problem and the optimization in question.
STRATEGIC ALLIANCES AS A KIND OF «SOFT» INTEGRATED CORPORATIONS (CONCEPTUAL APPROACHES TO ANALYSIS AND RECOMMENDATIONS FOR ORGANIZATIONAL DESIGN)
Authors: Lunkin A.N.
Published: February 2020

The article systematizes the conceptual framework and conceptual guidelines for the implementation of various forms of integration of economic entities, respectively — for the formation, functioning and development of various forms of integrated corporations, or integrated corporate structures (ICS). The importance of soft forms of ICS, including strategic alliances based on long-term strategic agreements of participating organizations, is shown. Definitions of strategic alliances and the ability of organizations to form them (the ability of organizations to form alliances) are given. A set of conditions for ensuring the balance of education and production spheres is described as a necessary prerequisite for effective integration of the organization of these spheres. On the example of educational institutions and industrial enterprises, recommendations are given for the formation of strategic alliances of various types: bilateral, multilateral and multi-level.
Increasing uptake of hepatitis C virus infection case-finding, testing, and treatment in primary care: evaluation of the HepCATT (Hepatitis C Assessment Through to Treatment) trial
Authors: Horwood Jeremy , Clement Clare , Roberts Kirsty , Waldron Cherry-Ann , Irving William L , Macleod John , Hickman Mathew
Published: February 2020

Background

Hepatitis C virus (HCV) infection is a key cause of liver disease but can be cured in more than 95% of patients. Around 70 000 people in England may have undiagnosed HCV infection and many more will not have been treated. Interventions to increase case-finding in primary care are likely to be cost-effective; however, evidence of effective interventions is lacking. The Hepatitis C Assessment Through to Treatment (HepCATT) trial assessed whether a complex intervention in primary care could increase case-finding, testing, and treatment of HCV.

Aim

To investigate the feasibility and acceptability of the HepCATT intervention.

Design and setting

A qualitative study with primary care practice staff from practices in the south west of England taking part in the HepCATT trial.

Method

Semi-structured interviews were carried out with GPs, nurses, and practice staff to ascertain their views of the HepCATT intervention at least 1 month after implementing the intervention in their practice. Normalisation process theory, which outlines the social processes involved in intervention implementation, informed thematic data analysis.

Results

Participants appreciated the HepCATT intervention for increasing knowledge and awareness of HCV. Although some initial technical difficulties were reported, participants saw the benefits of using the audit tool to systematically identify patients with HCV infection risk factors and found it straightforward to use. Participants valued the opportunity to discuss HCV testing with patients, especially those who may not have been previously aware of HCV risk. Future implementation should consider fully integrating software systems and additional resources to screen patient lists and conduct tests.

Conclusion

When supported by a complex intervention, primary care can play a crucial role in identifying and caring for patients with HCV infection, to help stem the HCV epidemic, and prevent HCV-related illness.
Brief interventions for obesity when patients are asked to pay for weight loss treatment: an observational study in primary care with an embedded randomised trial
Authors: Tudor Kate , Jebb Susan A , Manoharan Indrani , Aveyard Paul
Published: February 2020

Background

A brief intervention whereby GPs opportunistically facilitate an NHS-funded referral to a weight loss programme is clinically and cost-effective.

Aim

To test the acceptability of a brief intervention and attendance at a weight loss programme when GPs facilitate a referral that requires patients to pay for the service.

Design and setting

An observational study of the effect of a GP encouraging attendance at a weight loss programme requiring self-payment in the West Midlands from 16 October 2018 to 30 November 2018, to compare with a previous trial in England in which the service was NHS-funded.

Method

Sixty patients with obesity who consecutively attended primary care appointments received an opportunistic brief intervention by a GP to endorse and offer a referral to a weight loss programme at the patient’s own expense. Participants were randomised to GPs who either stated the weekly monetary cost of the programme (basic cost) or who compared the weekly cost to an everyday discretionary item (cost comparison). Participants were subsequently asked to report whether they had attended a weight loss programme.

Results

Overall, 47% of participants (n = 28) accepted the referral; 50% (n = 15) in the basic cost group and 43% (n = 13) in the cost comparison group. This was significantly less than in a previous study when the programme was NHS-funded (77%, n = 722/940; P<0.0001). Most participants reported the intervention to be helpful/very helpful and appropriate/very appropriate (78%, n = 46/59 and 85%, n = 50/59, respectively) but scores were significantly lower than when the programme was NHS-funded (92% n = 851/922 and 88% n = 813/922, respectively; P = 0.004). One person (2%) attended the weight loss programme, which is significantly lower than the 40% of participants who attended when the programme was NHS-funded (P<0.0001).

Conclusion

GP referral to a weight loss programme that requires patients to pay rather than offering an NHS-funded programme is acceptable; however, it results in almost no attendance.
THE ROLE OF ENDOSCOPIC ULTRASOUND IN DIAGNOSIS OF CHRONIC PANCREATITIS
Authors: Tran Van Huy , Phan Trung Nam , Vinh Khanh
Published: February 2020

Background and aims: To evaluate the efficacy of endoscopic ultrasound for diagnosis chronic pancreatitis by Rosemont classification. Patients and methods: A cross – sectional study was conducted on patients undergoing endoscopy ultrasound to diagnose chronic pancreatitis. Results: Study on a total of 57 patients indicated for endoscopic ultrasound. We have some following results: The lesions of chronic pancreatitis on endoscopic ultrasound: The hyperechoic foci without shadowing and stranding is 82.5% and hyperechoic foci with shadowing is 70.2%, cyst and pseudocyst are about 15.8%. Main pancreatic duct dilation is 71.9%, hyperechoic main pancreatic duct wall is 70.2%, main pancreatic duct stone is about 45.6%. Rosemont classification in diagnosis of chronic pancreatitis: Consistent with chronic pancreatitis by 1 major A feature (+) ≥ 3 minor features is 69.4% and 2 major A features is 30,6%. Suggestive of chronic pancreatitis by over 5 minor features is 100%. EUS is more accurate than CT in detecting early chronic pancreatitis. Conclusions:Endoscopic ultrasound is a highly effective method of diagnosing chronic pancreatitis. Key words: chronic pancreatitis, endoscopic ultrasound
Dinitro Derivatives of 3,6,7,8-tetraazatricyclo$[1^{1,5}. 1^{1,5}.1^{2,4}. 1^{2,4}]$octa-1,4-diene – A DFT Treatment
Authors: Türker Lemi
Published: February 2020

Nitramines constitute an important class of explosive materials. In the present study three isomeric dinitro derivatives (nitramines) of the title structure have been investigated quantum chemically within the constraints of density functional theory at the level of B3LYP/6-311++G(d,p). Certain energies, quantum chemical and spectral properties of these three isomeric dinitro derivatives of the parent tetraazatricyclo structure have been obtained and discussed.
Dinitro Derivatives of 3,6,7,8-tetraazatricyclo[11,5. 11,5.12,4. 12,4]octa-1,4-diene – A DFT Treatment
Authors: Türker Lemi
Published: February 2020

Nitramines constitute an important class of explosive materials. In the present study three isomeric dinitro derivatives (nitramines) of the title structure have been investigated quantum chemically within the constraints of density functional theory at the level of B3LYP/6-311++G(d,p). Certain energies, quantum chemical and spectral properties of these three isomeric dinitro derivatives of the parent tetraazatricyclo structure have been obtained and discussed.
DOSTUPNOST MEDICÍNSKÝCH ELEKTRONICKÝCH INFORMAČNÍCH ZDROJŮ V ČESKÉ REPUBLICE
Authors: Maixnerová Lenka
Published: February 2020

V roce 2017 byl zahájen projekt CzechElib, jehož cílem je zlepšit přístup k elektronickým informačním zdrojům (EIZ) v ČR. V rám-ci organizační struktury Národní technické knihovny vzniklo národní centrum CzechElib. Centrum zajišťuje výběr EIZ, kterým bude poskytnuta centrální finanční podpora, provádí výběrová řízení na dodavatele EIZ, sjednává licenční smlouvy a vlastní nákup. Členy projektu jsou vysoké školy, výzkumné ústavy, knihovny a nemocnice. Jedním z členů je i Národní lékařská knihovna, která zajišťuje přístup k EIZ pro obor lékařství a zdra-votnictví. Z dalších institucí, zajišťujících přístup k medicínským EIZ to jsou: 9 nemocnic, 11 výzkumných ústavů a 13 univerzit.Centrální finanční podporu mohou získat pouze instituce, které byly schváleny jako výzkumné organizace na Ministerstvu školství, mládeže a tělovýchovy. Centrum zajišťuje pouze EIZ, o které mají zájem minimálně 3 instituce.Prostřednictvím CzechElibu bylo pro rok 2018 zajištěno při-bližně 13 všeobecných EIZ (včetně 2 citačních) a 17 EIZ zaměře-ných na lékařské vědy. Všechny zdroje jsou zahraniční. Přístup k EIZ je vždy ošetřen licenčními smlouvami, některé zdroje mohou využívat pouze zaměstnanci instituce, akademic-ká obec, studenti nebo všichni registrovaní uživatelé, vždy by měla být možnost tzv. walk-in users na místě samém. Možnost vzdáleného přístupu do medicínských EIZ pro širokou veřejnost zajišťují zejména odborné knihovny (Národní lékařská knihov-na, Národní technická knihovna, Knihovna Akademie věd ČR), u některých i Univerzita Karlova.Na vzorku 50 časopiseckých titulů s nejvyšším impact fac-torem pro obor lékařské vědy byla ověřena jejich dostupnost v ČR. Obdobně byla ověřena dostupnost základních časopisů pro obory: všeobecné lékařství, pediatrie a diabetologie.Dostupnost byla ověřována v CzechElibu, v portálu Medvik, v EZB (Elektronische Zeitschriftenbibliothek) a ve VPK (Virtuální polytechnická knihovna).
DEFINICE SOUKROMÍ PACIENTA V ELEKTRONICKÝCH ZDRAVOTNÍCH ZÁZNAMECH
Authors: Matejak Marek , Seidl Libor , Potůček Michal
Published: February 2020

Elektronizace zdravotnictví je trend, který se už nedá zastavit. Výhody automatického zpracování a poskytování zdravotních záznamů často zastiňuje fakt, že se jedná i o údaje osobní a citlivé. Tedy jejich zpracování a sdílení by mělo být řízeno zabezpečeně, a to výhradně akceptováním všech souhlasů od pacienta = vlastníka těchto zdravotních dat. V neposlední řadě by pro každou podezřelou operaci nad účtem pacienta nebo s jeho osobními a citlivými údaji mělo být vždy možné zjistit čas a identitu přistupujícího uživatele.
OD INFORMACÍ KE ZNALOSTEM: MEDICÍNSKÉ INFORMACE V DATABÁZÍCH I V ROZHODOVACÍCH SYSTÉMECH
Authors: Polášková Alexandra , Dostálová Taťjana , Štěpánek Lubomír , Kříž Pavel , Feberová Jitka , Papík Richard
Published: February 2020

Informace, resp. vědecké informace v informačních systémech se přesouvají do systémů vyšší kategorie, např. znalostních a rozhodovacích. Velmi dobře znázorňuje tuto záležitost tzv. 4S Haynesova pyramida. Kategorizace a efektivita přístupu k medicínským informacím. Případová oblast: stomatologie a systémy podpory klinického rozhodování.