Investigation of thermodynamic properties of organic substances

Scientific and ptactical significance of the investigations in the field of thermodynamics of organic compounds is discussed. The apparatuses and methods used in LTOC (the Laboratory of Thermodynamics of Organic Compounds, Research Institute for Physical Chemical Problems, Belarusian State University) for experimental determination of thermodynamic properties of substances are described. They are adiabatic calorimetry and DSC of the heat bridge type for the measurements of heat capacities and enthalpies of phase transitions in the con-densed state, heat flow differential microcalorimeter of the Calvet type to obtain en-thalpies of evaporation, calorimeters for combustion of organic substances for determination of the enthalpies of combustion and formation, the apparatus for measurements of saturated vapor pressure by the integral effusion Knudsen method. The main results of studies of chemical and phase equilibria,thermodynam-ics of isomerization, improvements of additive methods for calculation of thermo-dynamic properties, investigations of plastic crystals of organic compounds and ionic liquids, calculations by the methods of statistical thermodynamics are re-ported. The information concerning development of the methods of calculation of chemical exergies in LTOC and thermodynamic substantiation of energy and resource saving technologies of organic production of Republic of Belarus is give

Experimental Spinal Fusion With Recombinant Human Bone Morphogenetic Protein-2 Without Decortication of Osseous Elements

Study Design. L4-L5 intertransverse process fusions were produced with 58 μg, 230 μg, or 920 μg of recombinant human bone morphogenetic protein-2 in 20 dogs. Eleven had traditional decortication of posterior elements before insertion of the implant. Nine were left undecorticated. All animals were evaluated 3 months after surgery. Objectives. To determine whether decortication is a prerequisite for successful fusion in the presence of osteoinductive proteins such as bone morphogenetic protein-2. Summary of Background Data. Recombinant osteoinductive proteins can induce de novo bone in ectopic soft-tissue sites in the absence of bone marrow elements. Traditional methods for achieving spinal fusion rely on exposure of bone marrow through decortication to facilitate osteogenesis. It is hypothesized that the presence of an implanted osteoinductive protein obviates the need for exposure and release of host inductive factors. Methods. Recombinant human bone morphogenetic protein-2-induced intertransverse process fusions were performed with and without decortication. Fusion sites were evaluated by computed tomography imaging, high-resolution radiography, manual testing, mechanical testing, and histologic analysis. Results. One hundred percent of decorticated spines and 89% of undecorticated spines were clinically fused by 3 months. Ninety-one percent of decorticated spines and 78% of undecorticated specimens exhibited bilateral transverse process osseous bridging. The only spines that failed to achieve solid bilateral arthrodesis were in the lowest dose group. With the higher two doses, there was histologic evidence of osseous continuity between the fusion mass and undecorticated transverse processes. Conclusions. There were no statistical differences in clinical and radiographic fusion rates between decorticated and undecorticated sites. With higher doses of recombinant human bone morphogenetic protein-2, there was little histologic distinction between fusions in decorticated versus undecorticated spines

Effective Doses of Recombinant Human Bone Morphogenetic Protein-2 in Experimental Spinal Fusion

Study Design Nineteen dogs underwent L4-L5 intertransverse process fusions with either 58 μg, 115 μg, 230 μg, 460 μg, or 920 μg of recombinant human bone morphogenetic protein-2 carried by a polylactic acid polymer. A previous study (12 dogs) compared 2300 μg of recombinant human bone morphogenetic protein-2, autogenous iliac bone, and carrier alone in this model. All fusions subsequently were compared. Objectives To characterize the dose-response relationship of recombinant human bone morphogenetic protein-2 in a spinal fusion model. Summary of Background Data Recombinant osteoinductive morphogens, such as recombinant human bone morphogenetic protein-2, are effective in vertebrate diaphyseal defect and spinal fusion models. It is hypothesized that the quality of spinal fusion produced with recombinant human bone morphogenetic protein-2, above a threshold dose, does not change with increasing amounts of inductive protein. Methods After decortication of the posterior elements, the designated implants were placed along the intertransverse process space bilaterally. The fusion sites were evaluated after 3 months by computed tomography imaging, high-resolution radiography, manual testing, mechanical testing, and histologic analysis. Results As in the study using 2300 μg of recombinant human bone morphogenetic protein-2, implantation of 58–920 μg of recombinant human bone morphogenetic protein-2 successfully resulted in intertransverse process fusion in the dog by 3 months. This had not occurred in animals containing autograft or carrier alone. The cross-sectional area of the fusion mass and mechanical stiffness of the L4-L5 intersegment were not dose-dependent. Histologic findings varied but were not related to rhBMP-2 dose. Inflammatory reaction to the composite implant was proportional inversely to the volume of the fusion mass. Conclusions No mechanical, radiographic, or histologic differences in the quality of intertransverse process fusion resulted from a 40-fold variation in dose of recombinant human bone morphogenetic protein-2

Энергоемкость углеводородов в жидком и твердом состояниях

Objectives. The increased use of unmanned aerial vehicles necessitates the search for jet fuels based on hydrocarbon materials with high energy intensity and physical density. The purpose of the work was to analyze the influence of various factors on the mass energy intensity of hydrocarbons. This analysis is required to substantiate the algorithm for locating energy-intensive CnHm structures.Methods. Combustion energy was calculated using additive procedures. The calculations were performed using Microsoft Excel.Results. During the analysis of the mass energy intensity of CnHm hydrocarbons, the m/n ratio was discovered to be the decisive factor for achieving high values of the mass energy intensity of hydrocarbons. The energy intensity decreases when moving from alicyclic to cyclic hydrocarbons, and this decrease is not compensated by the production of strain energy. An additive scheme that allows the molar volume of hydrocarbons to be predicted with sufficient accuracy is proposed for calculating the volumetric enthalpies of combustion.Conclusions. According to the thermodynamic analysis, n-alkanes have the highest mass energy intensities. The technology for extracting n-alkanes from oil fractions is well developed, and a decrease in the hydrogen content in the fuel results in a decrease in the mass energy intensity. It appears improbable that the mass and volumetric energy intensities of hydrocarbons seem will reach their maximum values simultaneously. Hydrocarbons that have a high m/n value, 2, 3, 4, 5, 6-membered rings, and phenyl fragments may have relatively high mass and volumetric energy intensities at the same time.Цели. Расширение сфер использования беспилотных летательных аппаратов требует поиска реактивных топлив с высокой энергоемкостью и физической плотностью на основе углеводородных материалов. Цель работы заключалась в проведении анализа влияния различных факторов на массовую энергоемкость углеводородов, необходимого для обоснования алгоритма поиска энергоемких структур CnHm.Методы. Энергия сгорания рассчитывались с использованием аддитивных процедур. Расчеты проводились в программе MS Excel.Результаты. В ходе проведенного анализа массовой энергоемкости углеводородов CnHm было установлено, что решающим фактором для достижения высоких значений массовой энергоемкости углеводородов является отношение m/n. При переходе от алициклических углеводородов к циклическим энергоемкость снижается, и данное снижение не компенсируется возникающей энергией напряжения. Предложена аддитивная схема, позволяющая с достаточной точностью предсказать молярный объем углеводородов для расчета объемных энтальпий сгорания.Заключение. Термодинамический анализ показал, что максимальной массовой энергоемкостью обладают н-алканы, технология извлечения которых из нефтяных фракций хорошо отработана, уменьшение же содержания водорода в топливе приводит к снижению массовой энергоемкости. Одновременное достижение максимальных значений массовых и объемных энергоемкостей углеводородов представляется маловероятным. Возможно, одновременно более высокой массовой и объемной энергоемкостью будут обладать углеводороды с высоким значением m/n, содержащие 2, 3, 4, 5, 6-ти членные циклы и фенильные фрагменты

Thermodynamics of the Antiviral and Antiparkinsonian Drug Amantadine Hydrochloride: Condensed State Properties and Decomposition

© 2017 American Chemical Society. Heat capacities of the antiviral and antiparkinsonian drug amantadine hydrochloride in the crystalline state were measured by adiabatic and differential scanning calorimetry in the temperature range from 5 K to 470 K. Two unresolved low-enthalpy solid-to-solid phase transitions with peak maxima at 120.0 K and 123.1 K were detected. Thermodynamic functions for crystalline amantadine hydrochloride were derived from the data obtained. Decomposition of amantadine hydrochloride was studied by the Knudsen effusion method. Quantum chemical calculations supported completeness of the amantadine hydrochloride ionic pair disintegration under the effusion conditions. A data treatment model considering the difference in effusion rates of the decomposition products, anisotropy failure in the vicinity of the orifice, and vapor undersaturation in the effusion cell was developed. Thermodynamic parameters for the decomposition were thus derived and shown to be consistent with available literature data on decomposition of similar organic hydrochlorides and with the entropy of reaction calculated directly from the entropies of the decomposition reaction participants. The obtained set of thermodynamic properties of the medication is expected to provide new key information necessary for optimization of production and storage conditions. (Graph Presented)

Thermodynamic similarity of stacked-cup multiwall carbon nanotubes and graphite

When conducting photo elicitation interviews (PEI), researchers introduce photographs into the interview context. Although PEI has been employed across a wide variety of disciplines and participants, little has been written about the use of photographs in interviews with children. In this article, the authors review the use of PEI in a research study that explored the perspectives on camp of children with cancer. In particular, they review some of the methodological and ethical challenges, including (a) who should take the photographs and (b) how the photographs should be integrated into the interview. Although some limitations exist, PEI in its various forms can challenge participants, trigger memory, lead to new perspectives, and assist with building trust and rapport

Leaving no disease behind: The roadmap to securing universal health security and what this means for the surveillance of infectious diseases in Ghana as a precedent for sub-Saharan Africa

Introduction: Ghana is the first country in sub-Saharan Africa (SSA) to aim for universal health coverage (UHC). Based on Ghana's UHC system, the accessibility and distribution of healthcare facilities were evaluated for 2020. Projecting into 2030, this study aimed at providing geographical information data for guiding future policies on siting required healthcare facilities. Ghana as a precedent for SSA was evaluated and proposed to "leave no disease behind" in the surveillance of infectious diseases (IDs). This is to reinforce the sustainable development goals (SDG) 3 agenda on health that underpins monitoring equity in "leaving no one behind." Methods: Geospatial accessibility, travel time data, and algorithms were employed to evaluate the universality and accessibility of healthcare facilities, and their future projections to meet UHC by 2030. Healthcare facilities as surveillance sites were compared to community-based surveillance to identify which would be more applicable as a surveillance system to leave no disease behind in Ghana. Findings: Ghana has 93.8%, 6.1% and 0.1% as primary, secondary and tertiary healthcare facilities respectively. It has 26.1% of healthcare facilities remaining to meet the SDG 3 health target by 2030. In terms of providing quality healthcare, 29.3% and 67.2% of the additional required healthcare facilities for optimal allocation and achieving the UHC target need to be secondary and tertiary respectively. In assessing the broad spectrum of IDs studied from 2000 to 2020, an average of 226 IDs were endemic or potentially endemic to Ghana. The majority of the studies carried out to identify these IDs were done through community-based surveillance. Conclusion: Establishing community-based surveillance sites to leave no disease behind and also providing the required healthcare facilities to reinforce leaving no one behind will enhance the universal health security of Ghana as a precedent for SSA

Validation of a 3D CT method for measurement of linear wear of acetabular cups: A hip simulator study

Background We evaluated the accuracy and repeatability of a 3D method for polyethylene acetabular cup wear measurements using computed tomography (CT). We propose that the method be used for clinical in vivo assessment of wear in acetabular cups. Material and methods Ultra-high molecular weight polyethylene cups with a titanium mesh molded on the outside were subjected to wear using a hip simulator. Before and after wear, they were (1) imaged with a CT scanner using a phantom model device, (2) measured using a coordinate measurement machine (CMM), and (3) weighed. CMM was used as the reference method for measurement of femoral head penetration into the cup and for comparison with CT, and gravimetric measurements were used as a reference for both CT and CMM. Femoral head penetration and wear vector angle were studied. The head diameters were also measured with both CMM and CT. The repeatability of the method proposed was evaluated with two repeated measurements using different positions of the phantom in the CT scanner. Results The accuracy of the 3D CT method for evaluation of linear wear was 0.51 mm and the repeatability was 0.39 mm. Repeatability for wear vector angle was 17?. Interpretation This study of metal-meshed hip-simulated acetabular cups shows that CT has the capacity for reliable measurement of linear wear of acetabular cups at a clinically relevant level of accuracy