Morphology, thermal and mechanical properties of electrospun polyvinylidene/polyethylene glycol composite nanofibers as form-stabilized phase change materials

Polyvinylidene fluoride (PVDF)/polyethylene glycol (PEG) form-stabilized composite phase change nanofibers with various mass percentage of PEG1000 (with average molecular weight of 1000) loadings were fabricated by electrospinning technique, in which PEG was served as phase change material (PCM) and PVDF as the supporting matrix to afford a mechanically strong structure. Effect of PEG1000 content on nanofiber morphology, phase transition properties, thermal stability, thermal energy storage and release performance, and mechanical properties were studied experimentally. The results showed that the incorporation of PEG1000 improved the spinning solution viscosity and high mass fraction of PEG1000 in the nanofibers led to decreased fiber diameter and melting temperature, and higher latent heat of fusion. In addition, mechanical test revealed that the fracture elongation of the electrospun PVDF/PEG composite nanofibrous membranes were initially increased with unobvious tensile strength changes, while the value of the elongation would decrease, and the tensile strength increase as the mass ratio of PVDF/PEG lower to 1:1. Furthermore, the melting temperature and maximum latent heat for PVDF/PEG were determined from DSC measurement as 51.8 °C, and 73.3 J/g, when the mass radio of PVDF/PEG was 1:1 (w/w), which was suitable utilized for thermo-regulating textiles or in heat storage devices.

Effects of ashwagandha root extract on physical performance – a clinical review

Sport is an important aspect of human life, affecting mental and physical health. Physical activity is one of the most effective ways of preventing the diseases of civilisation, such as coronary heart disease, hypertension, obesity and diabetes. There are many substances and methods that are used by athletes to improve physical performance, increase muscle mass and strength, increase concentration or suppress excessive emotions or reduce body weight to improve sports results. However, there is a need for research to find natural substances of plant origin, the use of which will lead to an increase in physical performance and will be fully legal and without side effects. Some scientists are conducting research into the use of ashwagandha root extract to improve physical performance. The aim of this study was to assess the efficacy and safety of ashwagandha root extract in the treatment of insomnia, anxiety and in reducing stress. Our study material consisted of publications, which were found in PubMed, ResearchGate and Google Scholar databases. In order to find the proper publications, the search has been conducted with the use of a combination of key words like: ''ashawagandha'', ''physical performance'', ''physical endurance'', ''muscle strength". The first step was to find proper publications from the last 15 years. The second step was to carry out an overview of the found publications.

Friction Stir Processing of Additively Manufactured Ti-6Al-4V Alloy: Structure Modification and Mechanical Properties

This work explores the possibility of using friction stir processing to harden the Ti-6Al-4V titanium alloy material produced by wire-feed electron beam additive manufacturing. For this purpose, thin-walled workpieces of titanium alloy with a height of 30 cm were printed and, after preparation, processed with an FSW-tool made of heat-resistant nickel-based superalloy ZhS6U according to four modes. Studies have shown that the material structure and properties are sensitive to changes in the tool loading force. In contrast, the additive material’s processing direction, relative to the columnar grain growth direction, has no effect. It is shown that increasing the axial load leads to forming a 𝛽-transformed structure and deteriorates the material strength. At the same time, compared to the additive material, the ultimate tensile strength increase during friction stir processing can achieve 34–69%.

Bioplastic Production from Eucheuma Cottoni

Plastic waste has become a global problem because it causes environmental pollution. This is because plastic waste is difficult to decompose. There have been numerous solutions proposed, one of which is theuse of bioplastics. In this research, the bioplastics were made from third- generation biomass, namely the eucheuma cottoni. Eucheuma cottoni is contains biopolymer carrageenan, a carbohydrate with unit structures consisting of d-galactose and 3,6 anhydrogalactose with glycosidic bonds. Goal this research is study the effects of sorbitol plasticizer content and bioplastics manufacturing temperature on bioplastics, tensile strength, elongation, and biodegradation rate. The bioplastics were made by extracting 10 grams of eucheuma cottoni powder in 200 ml of distilled water. The algae extract was added with sorbitol (plasticizer) and heated at various temperatures from 45°C until 60°C. The mixture was poured into a mold tin and dried in the oven to a constant weight. The resulting bioplastics were then characterized to determine the tensile strength and biodegradation rate. The results showed that increasing the plasticizer content from 3.5% reduced the tensile strength, however, it increased the elongation and biodegradation rate. The optimal plasticizer content was 4% with a tensile strength value of 4.8309 Mpa, elongation of 24.1548%, and biodegradation rate of 26.9392%. The temperature variable showed that increasing the temperature of making bioplastics could reduce tensile strength, increase elongation and biodegradation rate of bioplastics. The optimum temperature for making bioplastics at 45oC obtained a tensile strength of6.28 Mpa and an elongation of 20.67%. The biodegradation rate was 39.6665%, and the best sorbitol content was received at 4%.

Friction Stir Welded AA5052-H32 under Dissimilar Pin Profile and Preheat Temperature: Microstructural Observations and Mechanical Properties

In order to meet the escalating demand in the shipbuilding business, suitable materials with enhanced qualities are required to maximize ship cargo while reducing fuel consumption. Aluminum (Al) and its alloys are competing contenders for use in a variety of complicated ship structures. The major challenge to enhancing joint quality and performance is the quest for a viable and efficient FSW parameter. The main focus of this study was to critically explore the effect of the tool pin profile and the preheat temperature used during the friction stir welding of AA 5052-H32 on its mechanical properties and weld microstructure characteristics. There are three pin profile variations, including samples that were cylindrical, samples with two flat sides, and samples with three flat sides, all of which were investigated in different preheat temperatures (150–300 °C). The results that were obtained during macrographic observation showed that tunnel defects were visible in the cylindrical and two-flat-sided pin profile designs. During observations of the microstructure, it was observed that the grain size became finer and smaller in the weld nugget compared to in the heat affected zone (HAZ) and thermo-mechanically affected zone (TMAZ) regions due to dynamic recrystallization. However, at the 300 °C preheat variation, the grain size appeared to be larger due to the slower cooling rate, causing a decrease in the mechanical properties of the samples. The results of the physical tests determined that the preheat temperature caused an increase in the mechanical properties until 250 °C, at which point the three-flat-sided pin profile tool demonstrated superior mechanical properties compared to the tools with a cylindrical design; a 12.2% tensile strength increase, a 15.3% and 9.4% face and root bending increase, and an 11.2% hardness increase were observed.

A numerical investigation of the statistical size effect in non-crimp fabric laminates under homogeneous compressive loads

The compressive strength of fiber reinforced composites is typically limited by a shear localization phenomenon known as microbuckling and is very sensitive to local imperfections of fiber alignment. Local misalignments act as randomly distributed flaws and introduce a dependence of the compressive strength on the size of material volume element under consideration. For homogeneously loaded material elements, weakest-link theory in combination with a Weibull power law is a frequently employed statistical model for microbuckling strength. This implies a dependence of strength on the size of volume under consideration. The present contribution investigates the strength–size relation for a non-crimp fabric via a numerical approach. Characteristics of the misalignment flaws used in simulations are derived from a comprehensive data set collected via large-scale measurements of roving dislocations on dry fiber material. Predictions resulting from the weakest-link Weibull theory are compared against strength–size statistics gathered by numerical analysis. In this manner, the size effects in single plies and laminates are quantified. The main findings are that weakest-link Weibull theory is well suited to predict size related strength loss in individual plies. However, it is also found that when plies are bonded to form laminates, misalignments in individual plies are mitigated in a way that is inconsistent with the weakest-link assumption. In all situations considered here, the strength loss expected from weakest-link Weibull theory was outweighed by a strength increase due to the mitigation effect when the volume was increased by adding extra layers to a laminate.

Confinement of Masonry Columns with Natural Lime-Based Mortar Composite: An Experimental Investigation

The paper presents the results of an experimental campaign on the confinement of masonry square columns with fiber-reinforced lime mortar (FRLM) composites made of a natural lime-based matrix. The experimental results show the effectiveness of such a composite for increasing both strength and ductility performances of strengthened columns. Predictive formulas from the literature and from the Italian guidelines CNR-DT 215/2018 do not perfectly fit the experimental outcomes and do not confirm the strength increase of the confined columns. The reason can be attributed to the very low mechanical properties of the natural matrix used to form such a composite. Therefore, considering that the use of a natural and sustainable matrix fully compatible with the masonry substrate is a fundamental requirement for strengthening masonry columns of buildings belonging to architectural heritage, an additional future effort should be made by researchers involved in this field. In particular, for a reliable prediction of the strength of masonry columns confined with composites made of natural matrices, wider experimental campaigns are necessary to refine available formulas with respect to different substrates and component materials.

Efektivitas Penggunaan Intervensi Fisioterapi Terapi Latihan dan Infrared Pada Kasus Dislokasi Sendi Bahu

Kegiatan dasar berupa gerak merupakan suatu kebutuhan dan tuntutan manusia terutama dalam era globalisasi seperti sekarang. Anggota gerak atas memiliki keterlibatan yang sangat tinggi dalam semua aktivitas yang dilakukan oleh manusia. Seluruh aktivitas yang dilakukan sehari-hari banyak bergantung terutama pada fungsi anggota gerak atas. Tangan dan lengan merupakan pemeran utama, sehingga apabila terjadi gangguan tertentu, hal tersebut akan mengganggu mobilitas dan kegiatan manusia. Sendi bahu merupakan salah satu sendi besar yang paling umum terjadi dislokasi, hal tersebut dapat terjadi karena rentang gerak sendi yang luas, dangkalnya fossa glenoid, dan ligament laxity pada beberapa orang. Dislokasi sendi bahu merupakan suatu kondisi dimana terjadi pergeseran caput humerus dari sendi glenohumeral, sehingga hal tersebut dapat menyebabkan kerusakan pada saraf serta dapat terjadi berulang. Jurnal ini bertujuan untuk menjelaskan efektivitas pemberian intervensi terapi latihan dan terapi infrared pada kasus dislokasi sendi bahu dan menambah pengetahuan pembaca mengenai kasus dislokasi sendi bahu. Metode penelitian yang digunakan yaitu deskriptif kualitatif dengan pengambilan materi berbasis literature review. Hasil penelitian menunjukkan bahwa pemberian terapi latihan dan terapi infrared efektif untuk menurunkan nyeri, meningkatkan kekuatan otot, meningkatkan lingkup gerak sendi (LGS), serta meningkatkan kemampuan fungsional pasien yang menderita kasus dislokasi sendi. Basic activities are in the form of a necessity and human need, especially in the era of globalization as it is now. Upper limbs have a very high involvement in all activities carried out by humans. Everything that is done daily, especially activities on the function of the upper limbs. Hands and arms are the main actors, so that if certain disturbances occur, it will interfere with mobility and human activities. The shoulder joint is one of the most commonly dislocated large joints, this can occur due to the wide range of motion of the joint, the shallowness of the glenoid fossa, and ligament laxity in some people. Dislocation of the shoulder joint is a condition in which the humeral head shifts from the glenohumeral joint, so that it can cause nerve damage and can occur repeatedly. This journal aims to explain the effectiveness of providing exercise therapy and infrared therapy in shoulder dislocation cases and the reader's knowledge about shoulder dislocation cases. The research method used is descriptive qualitative by taking material based on a literature review. The results showed that providing exercise therapy and infrared therapy to reduce pain, increase muscle strength, increase range of motion, and improve the ability of patients suffering from joint dislocation cases.

Transition Zone Enhancement with Waste Limestone Powder as a Reason for Concrete Compressive Strength Increase

Modification of concrete with waste materials is an increasingly common process, and they are primarily used as a partial substitution for cement. In the case of inert or nearly inert additions according to EN 206, the effectiveness of such a modification mainly concerns ecological aspects and, only to a small extent, mechanical properties. This article analyses the effect of modifying cement concrete with waste limestone powder as a partial substitution for fine aggregate. The analysed waste arises as a result of the accumulation of dust produced during the initial preparation of aggregate for the production of hot mix asphalt (HMA). In order to analyse the effect of waste on compressive strength, an experimental design was prepared with variable substitution levels and variable water/cement ratios. Compressive strength tests were performed after 28 to 90 days. Statistical analysis of the results was performed. Microscopic evaluation of the fractures of the samples was carried out to clarify the mechanism of transition zone enhancement, which resulted in an increase of compressive strength of the composite.