Thermo- and pH-sensitive Hydrogels with Incorporated Multi-Walled Carbon Nanotubes

Carbon nanotubes (CNTs) attract great attention due to the unique combination of physical, chemical, electrical and mechanical properties which have high potential for design of nanocomposite materials with customized properties (electromagnetic shielding, high strength and electroconductivity materials), actua-tors (e.g. artificial muscles and tissues), sensors, components of microfluidic devices, etc. Usage of CNT in practical applications is limited by their lower solubility in most solvents. Remaining primary agglomer-ates of NT not only increase the amount of filler needed for percolation, but also act as imperfections under mechanical stress. Therefore, in this investigation, the influence of surfactant type and its concentration, along with sonication treating time on sedimentation behavior of multi-walled carbon nanotubes was in-vestigated. To a greater extent, the influence of monomer composition, surface-active substances, and car-bon nanotubes on gelation and physicochemical properties of thermo- and pH-sensitive hydrogels and hy-drogel nanocomposites based on N-isopropylacrylamide with carbon nanotubes were investigated too. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3559

Optimization of leather filling composition containing SiO2 nanoparticles

The global leather industry is looking for a cleaner leather processing technology to overcome its negative environmental impact. As an alternative to conventional processing, an ecofriendly filling composition based on fumed silica was developed and tested for the production of leather materials. Polycriterial optimization of the filling composition containing silica nanoparticles was conducted using the McLean-Anderson method by considering the type of mathematical model of the process “content-properties”. For optimization of the experimental conditions a multithreaded program based on calculation of informative and dispersive matrices and their determinants was developed. The optimal formulation of filling composition for the production of flexible leather materials was established and experimentally tested. The developed technology yields leather materials with increased volumetric yield and elasticity and more homogeneous microstructure when compared to the current company technology. The mathematical modelling discussed in the paper can be also used to solve similar problems for other technological processes

Regeneration of raw hide water balance by electrochemically activated water

Improving the collagen structure, which was impacted by the curing process, increases the efficiency of all subsequent structural transformations during leather production and results in the formation of a high-quality leather material. Herein, we studied the process of soaking green-salted horsehides in electrochemically activated aqueous solutions and the properties of resulting chrometanned leather. It was found that the process of soaking horsehides can be effectively carried out using an electrochemically activated solution (ECAS) – a mixture of catholyte and anolyte at a volume ratio of 5 : 1. Using this soaking solution, sodium sulfide (an environmentally harmful reagent), sodium carbonate, and detergent can be completely excluded from the technological solution. The use of ECAS at the soaking stage effectively regenerates the water balance of horsehides while maintaining a stable pH during the soaking process and increases the efficacy of liming and all subsequent processes. Considering the prominent structural differences (density and thickness) between the front and shell of horsehide, the developed method, which utilize ECAS for soaking, allows the entire process to be carried out on uncut horse hides instead of processing two parts separately, which is normally required. The chrome-tanned leather produced by the developed method in semi-industrial conditions has elastic-plastic properties which are superior compared to the leather produced by current technology. The developed method also results in increasing the area yield by 2.5%. The resulting elastic leather can be used for manufacturing a variety of articles, including clothing, accessories, and footwear

Thermosensitive Hydrogels and Microgels Based on N-isopropylacrylamide and Acrylamide with Incorporated Magnetite

Hydrogels with magnetic properties (ferrogels) are very promising for medical application, first of all, for the design of targeted delivery systems with controlled release of drugs and for magnetic hyperthermia and could be obtained using different techniques (ex- and in-situ syntheses). The present work is devoted to the study of magnetite (Fe3O4) formation inside the nanoreactors of (co)polymeric gels (hydrogels and mi-crogels) based on the derivatives of acrylic acid: N-isopropylacrylamide, acrylamide, and N,N-methylenbisacrylamide (crosslinking agent). Influence of hydrophilic–lipophilic balance of (co)polymeric templates, temperature, pH and concentration of iron cations on the magnetite formation inside polymeric matrixes were investigated along with the development of ferrogel preparation technique. Physical and chemical properties of obtained ferrogels have been studied with gravimetric analysis, thermogravimetric analysis, X-ray fluorescence spectroscopy, X-ray diffraction, optical and transmission microscopies, IR spec-troscopy, etc. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3544

Influence of Indifferent Electrolytes on Formation of Coagulative Structures in Aqueous Silica Dispersions

Effects of indifferent electrolytes (NaCl, KCl, LiCl, NaI, NaNO3, CaCl2, and MgCl2) on the electrical double layer (EDL), aggregation, gelling, and rheological properties of aqueous dispersions of nanosilica were investigated. All examined indifferent electrolytes enhance interactions between nanoparticles of fumed silica through the coagulation mechanism. The critical concentration of gelation and gelling time decrease in the presence of the electrolytes, while the effective viscosity of the dispersions and average size of aggregates (Def) increase in series of chlorides: Li+ < Na+ < K+ < Ca2+ < Mg2+. That corresponds to an increase in the cation radius and reduction of the hydration shell. The nature of anions and cations significantly affects the values of Def and viscosity. For sodium salts, the viscosity increases in series I- < NO3- < Cl- corresponding to an increase in the hydration shell

Bitten wounds of the maxillofacial area in children

The aim of the work is to determine the frequency, structure, features of clinical manifestations and treatment of bitten wounds of the face and neck in children of Poltava region. Materials and methods: It has been analyzed 91 histories of disease of thematic patients undergone treatment at the Surgical Department of Pediatric town clinical hospital of Poltava. Results: In the structure of traumatic injuries of maxillofacial area in children 5.3% were patients with bitten wounds of the face and neck. Among the injured were children of the age 7-12 years old (30.2%). In 74.7% of cases, the bites were complicated by acute inflammatory processes. Urban residents accounted for 71.8% of the total number of cases, while rural residents accounted for 28.2%. Boys were injured by 53.6% and girls by 46.4%. Sharps (74.5%), punctures (19.3%) and lacerations (6.2%) differed in form. The comprehensive treatment of patients with bitten maxillofacial area wounds was carried out according to the protocol of care. Conclusions: The clinical picture and severity of bitten wounds of maxillofacial area in children have individual features, which are largely due to topographic and anatomical localization of injuries. The choice of the optimal variant of primary surgical treatment of wounds and the amount of surgery should be determined individually depending on the severity of the injury, the time of injury. Special attention should be paid to normalization of psycho-emotional state of patients and prevention of scar formation

Clinical-morphological characteristics and peculiarities of treatment of paraururicular fistulas in children

The aim: Determining the frequency of occurrence of paraauricular fistula in children and comparing the results of their own experience regarding their clinical manifestations, treatment principles and morphological features with existing scientific data. Materials and methods: The results of a comprehensive examination and surgical treatment of 25 children with paraauricular fistulas. Results: Most often, para-auricular fistula was observed in infants 22 – (88%). In 18 persons (72%), they were unilateral, in 10 – (40%) hereditary. In 8 – (32%), fistula was diagnosed immediately after birth. In 17 – (68%) the pathology was not clinically manifested, but was an accidental finding during the next medical examination. Morphological research has shown that congenital paraauricular fistula is a formed canal intimately associated with the epithelium and cartilage, and the presence of epithelial lining on the fistula wall with constant support of the inflammatory process makes it impossible to heal even against the background of multicomponent treatment. Conclusions: Due to the topographic-anatomical localization, features of the clinic of the born fistula, surgical treatment does not always allow to achieve the desired results, and requires repeated interventions during recurrence. It is possible to prevent recurrence by the extensive use of additional diagnostic manipu

Resource-saving technologies for the production of elastic leather materials

This monograph contains a collection of recent research papers focusing on advancing existing technologies and developing new technologies to improve the environmentally friendliness and save resources during the production of elastic leather materials. The papers are organized based on the type of technological process used to preserve raw hides. A lot of attention is devoted to mathematical planning, simulations, and multicriteria optimization of the technological processes using newly developed chemical reagents. The monograph contains a complex study of physicochemical properties and characteristics of the resulting leather materials. The developed technologies were tested by the private joint-stock company Chinbar (Kyiv, Ukraine) and implemented at Ukrainian tanneries. Total number of figures – 58, tables – 95, and references – 491

Peculiarities of antenatal and postnatal periods of child development with inflammatory maxillofacilal localization processes

За 7 років обстежено 537 дітей з гострими гнійними одонтогенними і неодонтогенними процессами щелепно-лицевої ділянки. Встановлено , що в їх структурі превалювали гострий гнійний лімфаденіт (29 %) та аденофлегмона і одонтогенний остеомієліт, на долю яких припадало по 18 %. Аналіз перебігу вагітності засвідчив, що в цей період у матерів обстежених дітей досить часто простежувалися випадки гострих інфекційних захворювань, наявність патологічних станів і це певною мірою відображалося на пологовій діяльності. Характерним є також те, що діти , які знаходилися на штучному та змішаному вигодуванні з місячного та шестимісячного віку частіше хворіли. Така ситуація вказує на необхідність включення цих дітей до групи ризику з метою своєчасно оздоровлення, що може звести нанівець вплив несприятливих чинників, дію яких вони відчували як в анте - так і постнатальному періодах їх розвитку.For the period of 7 years, 537 children with acute purulent odontogenic and non-odontogenic processes of maxillofacial area were examined. Acute purulent lymphadenitis (29 %) and adenoflegmon and odontogenic osteomyelitis, which accounted for 18 %, were found to be predominant in their structure. Noteworthy is the fact that a large number of children and their relatives seek specialized care behind time and are often treated for the wrong diagnosis. There are also certain age differences depending on the nosological form of the disease. Analysis of pregnancy showed that in this period, in the examined children’s mothers cases of acute infectious diseases, the presence of pathological conditions were quite frequently observed, and this has reflected in childbirth. It is also noteworthy that infants who were in artificial and mixed feeding from the age of one month and six months were more likely to fall ill. This situation indicates the need to include these children to the risk group in order to timely recover, which can negate the impact of adverse factors that they have experienced in both the ante- and post-natal periods of their development