Influence of Al on the structure and in vitro behavior of hydroxyapatite nanopowders

Nanopowders of aluminum-substituted (0-20 mol %) hydroxyapatite (HA) with the average size of 40-60 nm were synthesized by the precipitation method from nitrate solutions. A series of samples were studied by various analytical tools to elucidate the peculiarities of al introductio

Motivation as a key element of psychological potential for entrepreneurial activities among the retired military personnel

The article considers with the problem of diagnosing the motivation of military personnel leaving the reserve, in order to assess their psychological potential for entrepreneurial activity. The currently known approaches to assessing the psychological potential of entrepreneurial activity are analysed. The necessity of identifying diagnostics of motivation as a key element for predicting the success of a serviceman who is transferred to the reserve in creating his own business is noted. Based on the analysis of the research results obtained during the implementation of the national project “Small Business Course” for military personnel and members of their families, the most significant motivators for two types of entrepreneurs were identified: innovators (capable of generating new ideas and modifying them from a business plan) and imitators ( who prefer to distribute previously developed technologies)

Fizičko-hemijske i biološke karakteristike dentalnih kalcijum silikatnih cemenata – Pregled literature

Dental cement materials have been developed with the aim to replace hard dental tissues. The first material used for pulp capping, root canal obturation, bifurcation perforation and apexification is calcium hydroxide (in 1920). A half century later, glass-ionomer cements began to suppress it as dentine substitutes. Finally, in the 1990s, calcium silicate (CS) material appeared in the dental research community as the most promising dentine substitute capable to adequately meet all clinical requirements. The aim of this paper is to present an overview of literature related to studies about CS materials taking into account their physical, chemical and biological properties and clinical applications. This review aims to discuss beneficial and adverse characteristics of CSs concerning interactions to the hard dentine and soft pulp/periodontal tissues. This review article deals with the literature data about currently commercially available CS concerning laboratory and clinical findings. 109 scientific articles were analyzed of which 62 references reported in vitro and 26 in vivo investigations while 21 references comprised reports, reviews and books dealing with both, in vitro and in vivo investigations. Although further data collection is necessary, CSs are promising materials that represent a gold standard for numerous dental clinical procedures. © 2019, Association of Chemists and Chemical Engineers of Serbia. All rights reserved

Silver-doped Calcium Phosphate bone cements with antibacterial properties

Calcium phosphate bone cements (CPCs) with antibacterial properties are demanded for clinical applications. In this study, we demonstrated the use of a relatively simple processing route based on preparation of silver-doped CPCs (CPCs-Ag) through the preparation of solid dispersed active powder phase. Real-time monitoring of structural transformations and kinetics of several CPCs-Ag formulations (Ag = 0 wt %, 0.6 wt % and 1.0 wt %) was performed by the Energy Dispersive X-ray Diffraction technique. The partial conversion of β-tricalcium phosphate (TCP) phase into the dicalcium phosphate dihydrate (DCPD) took place in all the investigated cement systems. In the pristine cement powders, Ag in its metallic form was found, whereas for CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, CaAg(PO₃)₃ was detected and Ag (met.) was no longer present. The CPC-Ag 0 wt % cement exhibited a compressive strength of 6.5 ± 1.0 MPa, whereas for the doped cements (CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt %) the reduced values of the compressive strength 4.0 ± 1.0 and 1.5 ± 1.0 MPa, respectively, were detected. Silver-ion release from CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, measured by the Atomic Emission Spectroscopy, corresponds to the average values of 25 µg/L and 43 µg/L, respectively, rising a plateau after 15 days. The results of the antibacterial test proved the inhibitory effect towards pathogenic Escherichia coli for both CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, better performances being observed for the cement with a higher Ag-content

Organizational Model of Universities in the USSR (1975-1985): Inertia or Innovation?

The article discusses an important problem of the organizational component in the functioning of universities. Along with the role of the social factor in the activities of universities, management models are attracting more and more attention of researchers. However, historians have studied this problem very little. While abroad, at least 3 models of “management” in universities are being actively developed. The Soviet experience is also of theoretical and practical interest for further reforming the higher education system.В статье рассматривается важная проблема организационной составляющей в функционировании вузов. Наряду с ролью социального фактора в деятельности вузов, управленческие модели привлекают все большее внимание исследователей. Однако историки очень мало изучают эту проблему, в то время как за рубежом активно разрабатываются по крайней мере 3 модели «управления» в университетах. Советский опыт также представляет теоретический и практический интерес для дальнейшего реформирования системы высшего образования

Radiation-induced stable radicals in calcium phosphates: Results of multifrequency epr, ednmr, eseem, and endor studies

This article presents the results of a study of radiation-induced defects in various synthetic calcium phosphate (CP) powder materials (hydroxyapatite—HA and octacalcium phosphate—OCP) by electron paramagnetic resonance (EPR) spectroscopy at the X, Q, and W-bands (9, 34, 95 GHz for the microwave frequencies, respectively). Currently, CP materials are widely used in orthopedics and dentistry owing to their high biocompatibility and physico-chemical similarity with human hard tissue. It is shown that in addition to the classical EPR techniques, other experimental approaches such as ELDOR-detected NMR (EDNMR), electron spin echo envelope modulation (ESEEM), and electronnuclear double resonance (ENDOR) can be used to analyze the electron–nuclear interactions of CP powders. We demonstrated that the value and angular dependence of the quadrupole interaction for14 N nuclei of a nitrate radical can be determined by the EDNMR method at room temperature. The ESEEM technique has allowed for a rapid analysis of the nuclear environment and estimation of the structural positions of radiation-induced centers in various crystal matrices. ENDOR spectra can provide information about the distribution of the nitrate radicals in the OCP structure. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Published under the CC BY 4.0 license.Authors would like to thank the Russian Foundation for Basic Research, project no. 18-29-11086. Institute of Solid State Physics, University of Latvia as the Center of Excellence received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01–2016-2017- TeamingPhase2 under grant agreement No. 739508, project CAMART2

Study of thermal effects of silicate-containing hydroxyapatites

The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 °С that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state

Immunomodulatory and neurotropic activities of synthetic peptides in a model of brain injury in rats

Treatment of consequences of traumatic brain injury (TBI) remains one of the current problems of medicine. To increase the effectiveness of treatment of post-traumatic complications, various drugs are recommended, including the peptide with neuromodulatory activity Semax.The present study aims to determine the presence of neuro- and immunoprotective properties of the synthetic peptide PR5, composed of fragments of proline-rich antimicrobial peptides.The work was performed on male Wistar rats weighing 300-350 g. The “falling weight” model of mechanical brain injury was used, which mainly causes diffuse brain damage. The synthesized peptide PR5, composed of fragments of known proline-rich peptides of animal neutrophils, and the peptide preparation Semax in the form of a 1% aqueous solution were used. The drugs were administered intranasally 1 hour after TBI, then twice a day for 4 days at a dose of 100 mg/kg body weight. Control animals received physiological saline in the same regimen as the peptide preparations.TBI led to a significant decrease in body weight, but in rats receiving the peptide preparation Semax, the decrease in body weight was significantly less than in control animals, and the PR5 preparation completely prevented the decrease in body weight after TBI. After TBI, the proliferative activity of lymphocytes was suppressed and the cytotoxicity of NK cells decreased. In animals treated with peptide preparations, there was no significant suppression of NK cell cytotoxicity, and the proliferative activity of lymphocytes was restored to the level of control animals by day 14 after TBI. Both peptide preparations used contributed to higher locomotor activity, and in animals treated with the PR5 peptide, this type of activity reached the parameters of control animals. The reduction in freezing duration in groups treated with peptide preparations indicates the presence of a sedative effect.The peptide preparation PR5 was active in this series of experiments, showing immunotropic and neuroprotective activity comparable to the Semax preparation. Further studies aimed at confirming the identified types of activity of the peptide preparation PR5 may justify its prospects for clinical use as a new nootropic agent

Сравнительная оценка заживления раны при использовании локального лоскута и полнослойного кожного трансплантата в реконструктивно-восстановительной хирургии головы и шеи

Objective: to present a comparative analysis of wound healing process and to evaluate the clinical effectiveness of using a local flap and a full-thickness skin graft in reconstructive surgery of head and neck skin tumors.Materials and methods. There were analyzed the results of 524 patients’ treatments in the Yaroslavl Regional Clinical Oncological Hospital over the period from 2000 to 2013. For 478 patients skin tumors excisions were performed by the reconstruction with a local flap, and for 46 patients – with a full-thickness skin graft. While making an assessment of wound healing it was considered the dynamics of clinical symptomatology, clinical laboratory measurements, the results of local thermometry, of bacteriological and morphological studies, as well as the results of wound-tensiometry studies. As a comparison of averages, they used Student’s t-test, Mann–Whitney test, χ2 test and Fisher’s exact test with statistically significant results at p < 0,05.Results. Comprehensive assessment of wound healing after skin tumors excisions of the head and neck with the elimination of the formed defect by using a local flap or a full-thickness skin graft showed that there was a vibrant local inflammatory reaction in both groups of patients up to 5–7 days after the operation. It was determined not only clinically, but also by objective criteria which characterized the wound healing process. Moreover, the hallmark of plastic reconstruction by skin graft was moderate intensity of local inflammation with the background of perceivable trophic abnormalities. Ultimately, the defined characteristics of wound healing process were as-sociated with a high incidence of complicated wound healing, up to 52.2 % using the skin graft and 33.1 % – the local flap. There were prevailed graft trophism problems in the complications structure in the form of partial or complete necrosis, which were particularly characterized for wound closing by free graft. From oncology position indicated wound risks were accompanied sufficiently high 5-year survival rate (81.8 and 93.9 %, respectively). Generally, choosing reconstructive surgery tactics to close the skin defect of the head and neck and considering a smaller percentage of complications it is preferred to use a local flap, in comparison with a free skin graft.Цель исследования – представить сравнительную характеристику течения раневого процесса и оценить клиническую эффективность использования локального лоскута и полнослойного кожного трансплантата в реконструктивной хирургии новообразований кожи головы и шеи.Материалы и методы. Проанализированы результаты лечения 524 пациентов в Ярославской областной клинической онкологической больнице в период с 2000 по 2013 г., среди которых 478 больным было выполнено иссечение новообразования кожи с реконструкцией локальным лоскутом, 46 – полнослойным кожным трансплантатом. При оценке заживления раны учитывали динамику клинической симптоматики, клинико-лабораторных показателей, данные локальной термометрии, бактериологического и морфологического исследований, а также ранотензиометрии. Для сравнения средних величин использовали t-критерий Стьюдента, критерий Манна–Уитни, критерий χ2 и точный критерий Фишера со статистической значимостью результатов при p < 0,05.Результаты. Комплексная оценка заживления раны после иссечения новообразования кожи головы и шеи с ликвидацией образовавшегося дефекта с помощью локального лоскута или полнослойного кожного трансплантата показала, что в обеих группах больных до 5–7 сут после операции наблюдалась выраженная местная воспалительная реакция. Она определялась не только клинически, но и посредством объективных критериев, характеризующих течение раневого процесса. При этом отличительной чертой пластики полнослойной кожей была умеренная выраженность локального воспаления на фоне ощутимых трофических нарушений. Выявленные особенности течения раневого процесса были сопряжены с высокой частотой встречаемости осложненного заживления раны, достигающей 52,2 % при закрытии раны кожным трансплантатом и 33,1 % – локальным лоскутом. В структуре осложнений превалировали проблемы, связанные с трофикой лоскута, в виде частичного или полного его некроза, которые были особенно характерны для закрытия раны свободной кожей. С онкологических позиций указанные риски со стороны раны сопровождались достаточно высокой 5-летней выживаемостью (81,8 и 93,9 % соответственно). В целом при выборе тактики выполнения реконструктивной операции для закрытия дефекта кожи головы и шеи с учетом меньшего процента осложнений предпочтительно использование локального лоскута по сравнению с пластикой свободным кожным трансплантатом

ЗАЖИВЛЕНИЕ РАНЫ И КЛИНИЧЕСКАЯ РЕЗУЛЬТАТИВНОСТЬ ПЕРВИЧНОГО ШВА В ХИРУРГИИ НОВООБРАЗОВАНИЙ МЯГКИХ ТКАНЕЙ ГОЛОВЫ И ШЕИ

Analyzed the results of treatment of 584 patients operated on for soft tissue tumors of the head and neck with the elimination of the defect formed by directly comparing the edges of wounds by primary suture. Taking into account the level of the wound by M.I. Kuzin et al. (1977), the dynamics of clinical and laboratory results, morphological, biological research, local thermometry and vulnotenziometry. Statistical significance was estimated using the Student's t-test, Mann–Whitney U-test, and criteria χ2 and Fisher with certainty changes in p < 0.05. Found that in the majority of patients kept the wound heals biologically programmed tissue reactions. At the same time, high bacterial contamination of integumentary tissues in the area of operations, especially against the background of the malignant tumor was a risk factor for the development of wound complications in 18 % of patients. The observed the oncological impact was characterized by the five-year survival at 90.6 ± 1.9 %. The 4.5 ± 1.9 % of patients had a direct link to death from malignant tumor.Анализированы результаты лечения 584 пациентов, оперированных по поводу опухоли мягких тканей головы и шеи с ликвидацией образовавшегося дефекта путем прямого сопоставления краев раны наложением первичного шва. С учетом стадийности раневого процесса по М.И. Кузину с соавт. (1977) представлена динамика результатов клинико-лабораторного, морфологического, бактериологического исследований, локальной термометрии и ранотензиометрии. Статистическая значимость оценивалась посредством t-критерия Стьюдента, критериев Манна–Уитни, χ2 и Фишера с достоверностью изменений при p < 0,05. Установлено, что у большинства больных заживление раны укладывалось в рамки биологически запрограммированных ткане- вых реакций. В то же время высокая бактериальная контаминация покровных тканей в зоне операции, особенно на фоне злокачественной опухоли, являлась фактором риска для развития раневых осложнений у 18 % пациентов. Наблюдаемая при этом онкологическая результативность характеризовалась 5-летней выживаемостью на уровне 90,6 ± 1,9 %. У 4,5 ± 1,9 % больных летальный исход имел прямую связь со злокачественной опухолью.