A review of diaphragmless shock tubes for interdisciplinary applications

Shock tubes have emerged as an effective tool for applications in various fields of research and technology. The conventional mode of shock tube operation employs a frangible diaphragm to generate shockwaves. The last half-century has witnessed significant efforts to replace this diaphragm-bursting method with fast-acting valves. These diaphragmless methods have good repeatability, quick turnaround time between experiments, and produce a clean flow, free of diaphragm fragments in contrast to the conventional diaphragm-type operation. The constantly evolving valve designs are targeting shorter opening times for improved performance and efficiency. The present review is a compilation of the different diaphragmless shock tubes that have been conceptualized, developed, and implemented for various research endeavors. The discussions focus on essential factors, including the type of actuation mechanism, driver-driven configurations, valve opening time, shock formation distance, and operating pressure range, that ultimately influence the shockwave parameters obtained in the shock tube. A generalized mathematical model to study the behavior of these valves is developed. The advantages, limitations, and challenges in improving the performance of the valves are described. Finally, the present-day applications of diaphragmless shock tubes have been discussed, and their potential scope in expanding the frontiers of shockwave research and technology are presented.Comment: Review paper, 31 pages, 18 figures, manuscript draf

EVALUATION OF PREHYPERTENSION, HYPERTENSION AND ITS ASSOCIATED FACTORS AMONG I YEAR MEDICAL STUDENTS

  Background and Objectives: Pre-hypertension is associated with increased progression to hypertension and cardiovascular risk. The objective of this study is to evaluate the prevalence of pre-hypertension and hypertension, as well as the associated factors among Ist year medical students who are from a similar socioeconomic status, dietary habits and lifestyle.Materials and Methods: This was a cross-sectional study conducted among 137 Ist year medical students using digital blood pressure (BP) monitor on three different occasions and the average was taken and also a questionnaire was obtained to assess the associated factors and other demographic details. Data were analyzed with the use of SPSS software and results were demonstrated using descriptive tables where Chi-square test and one-way analysis was used.Result: The prevalence of elevated BP (pre-hypertension and hypertension) as per JNC 7 criteria, among the medical students was 46.7%. There was a significant association of pre-hypertension with the individual risk factor like the family history of diabetes mellitus, diet and stress.Conclusion: The study shows a significant proportion of individuals with elevated BP at a younger age, associated with risk factors such as family history of diabetes, diet and stress. Elevated BP increases the risk for the development of hypertension during adolescence. Hypertension being a disease of iceberg goes unnoticed leading to chronic disease, therefore identification at the earliest can curb the disease.Keywords: Pre-hypertension, Adolescents, Prevalence, Hypertension

Kulikovskiyia gen. nov. (Bacillariophyceae) from the lateritic rock pools of the Western Ghats, India and from Hainan Province, China

A new triundulate naviculoid diatom genus is described from the Western Ghats of Peninsular India and Hainan Province, China. The new taxon, Kulikovskiyia gen. nov. has robust conical spines along its margin and at the apices and the external valve face has longitudinally‐oriented siliceous slat system extending the length of the valve. The external distal raphe ends bifurcate and terminates on the valve face. There appear to be superficial similarities between this Asian genus and species and Playaensis, a genus comprised of two species found only in the western USA. The systematic position of Kulikovskiyia is discussed, and other than noting its similarities to other biraphid naviculoid diatoms due to symmetry features and the position of the raphe, we are uncertain about its systematic placement at finer levels of classification.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153713/1/pre12400_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153713/2/pre12400.pd

Economic crisis management in construction projects - A Review

You Many of the construction industries have accepted increasing importance of economic crisis management to control risks. Economic crisis and their management have been critical issues which are related with projects, the construction company and their customers are related with higher chances of risk. The reason for their higher risk is their construction process and activities, their background and their organization. This study is related to economic crisis which immediately taken part in the construction project. The risk in the construction projects is usually identified as an event that highlights objectives of manpower, material and money. The ideas at various levels of construction industries have been collected through literature survey and their results have been analyzed in this paper. From this literature study, the situations influencing economic crisis were studied and recommendation has been expressed to devastate those economic crisis situations

Bactericidal Efficacy Of Antibiotic Combinations Against Enterococcus Faecalis – An In Vitro Study

Endodontics plays a major role in the eradication of pulpal inflammation, the primary goal includes the treatment of apical periodontitis and maintaining the pulpal health. An immature necrotic tooth poses various challenges in the management of pulpal necrosis which traditionally aims at the formation of calcific barrier that aid in the obturation. The prolonged duration of the procedure with multiple review appointments, and the risk of cervical fracture have posed a challenge in the conventional apexification procedures1. Regenerative endodontics is a biological based procedure designed to replace damaged structures such as dentin, root structures, and cells of the pulp-dentin complex. The evolution of the method of biologically replacing dental tissues by regeneration has overcome the challenges by increasing the root length and thickness of the root canal walls, inducing apexogenesis 2. The outcomes of regenerative procedures rely on the complete elimination of bacteria, facilitation of root development, and closure of sinus tracts3. The infection of the root canal system is polymicrobial, consisting of predominantly facultative anaerobes and anaerobic bacteria. The existence of bacterial species results in the persistence of apical periodontitis and inflammation4. The virulence of the bacteria on causing disease and tissue damage is proportionate to the type and the numbers of bacteria present5. The microbial flora in failed endodontic teeth normally include varied microorganisms of which Enterococcus faecalis is the most prevalent and highly resistant to intracanal medicaments6. It is an established fact that regeneration of the pulpal tissue of an infected immature tooth with open apex and apical periodontitis was considered to be impossible due to the presence of various microorganisms. Local antibiotics application has been widely used in the eradication of intracanal infection, hence the systemic routes of administration have been greatly reduced 7. To encounter the diverse flora in the root canal system, combinations of antibiotics are used known as the TRIPLE ANTIBIOTIC PASTE which comprises of combination of Ciprofloxacin, Metronidazole and Minocycline 8. The synergy of antibiotics used in the triple antibiotic paste is used to efficiently combat the polymicrobial environment in the infected root dentin 9. Minocycline is known for its broad-spectrum activity but has the disadvantage of discoloration of teeth which has led to the necessity of finding an alternative antibiotic. In this study in the triple antibiotic combination minocycline is replaced with clindamycin. This study aimed at comparing and evaluating the antibacterial efficacy of double or triple antibiotic combinations used as intracanal medicament. A standard strain of Enterococcus faecalis is used as a indicator organism to test the efficacy. The primary objective was to compare the efficacy of clindamycin over minocycline in combination with other antibiotic

Correlating Photoluminescence and Structural Properties of Uncapped and GaAs-Capped Epitaxial InGaAs Quantum Dots.

The understanding of the correlation between structural and photoluminescence (PL) properties of self-assembled semiconductor quantum dots (QDs), particularly InGaAs QDs grown on (001) GaAs substrates, is crucial for both fundamental research and optoelectronic device applications. So far structural and PL properties have been probed from two different epitaxial layers, namely top-capped and buried layers respectively. Here, we report for the first time both structural and PL measurements from an uncapped layer of InGaAs QDs to correlate directly composition, strain and shape of QDs with the optical properties. Synchrotron X-ray scattering measurements show migration of In atom from the apex of QDs giving systematic reduction of height and enlargement of QDs base in the capping process. The optical transitions show systematic reduction in the energy of ground state and the first excited state transition lines with increase in capping but the energy of the second excited state line remain unchanged. We also found that the excitons are confined at the base region of these elliptically shaped QDs showing an interesting volume-dependent confinement energy scaling of 0.3 instead of 0.67 expected for spherical dots. The presented method will help us tuning the growth of QDs to achieve desired optical properties

Experimental analysis and optimization of abrasive waterjet deep hole drilling process parameters for SS AISI 316L

Recent breakthroughs in component downsizing and miniaturization emphasise the requirement for deep-hole drilling with an increased aspect ratio, especially in the automobile sector for fuel injectors and the medical sector for manufacturing bone screws or surgical equipment. In this research, deep hole drilling on stainless steel AISI 316L has been conducted using an Abrasive Waterjet Machine (AWJM), and the influence of drilling variables on the material removal rate, roundness deviation of drilled holes have been evaluated to assess the machining and hole characteristics. In addition, machining parameters’ statistical relevance has been investigated using a multi-parametric analysis of variance. Quadratic mathematical models for material removal rate and roundness deviation have been established by correlating drilling parameters. The Grey Wolf Optimization (GWO) algorithm has been applied in this research to identify the optimal combination of deep hole drilling parameters for maximizing material removal rate and minimizing the roundness deviation. The results have been compared with Derivative-free optimization, Whale optimization, and Harmony search algorithms. The comparison revealed that the GWO algorithm performed better than other algorithms. In addition, a validation test has been carried out to confirm the accuracy of the results produced by the GWO. The images obtained from the scanning electron microscope showed that the surfaces of the deep holes are smooth. Additionally, the ploughing action was shown to be the principal mechanism responsible for removing the material. © 2023 The Author(s)Qatar National Research Fund, QNRF: MME03-1226-210042This work was supported by Qatar National Research Fund under the grant no. MME03-1226-210042 . The statements made herein are solely the responsibility of the authors

Stacked Cu1.8S nanoplatelets as counter electrode for quantum dot-sensitized solar cell

It is found that the electrocatalytic activity of Cu2-xS thin films used in quantum dot-sensitized solar cells (QDSSCs) as counter electrode (CE) for the reduction of polysulfide electrolyte depends on the surface active sulfide and disulfide species and the deficiency of Cu. The preferential bonding between Cu2+ and S2-, leading to the selective formation of a Cu1.8S stacked platelet-like morphology, is determined by the cetyl trimethyl ammonium bromide surfactant and deposition temperature; the crab-like Cu-S coordination bond formed dictates the surface area to volume ratio of the Cu1.8S thin films and their electrocatalytic activity. The Cu deficiency enhances the conductivity of the Cu1.8S thin films, which exhibit near-infrared localized surface plasmon resonance due to free carriers, and UV-vis absorption spectra show an excitonic effect due to the quantum size effect. When these Cu1.8S thin films were employed as CEs in QDSSCs, a robust photoconversion efficiency of 5.2% was obtained for the film deposited at 60 °C by a single-step chemical bath deposition method

Human embryonic stem cell-derived test systems for developmental neurotoxicity: a transcriptomics approach

Developmental neurotoxicity (DNT) and many forms of reproductive toxicity (RT) often manifest themselves in functional deficits that are not necessarily based on cell death, but rather on minor changes relating to cell differentiation or communication. The fields of DNT/RT would greatly benefit from in vitro tests that allow the identification of toxicant-induced changes of the cellular proteostasis, or of its underlying transcriptome network. Therefore, the 'human embryonic stem cell (hESC)- derived novel alternative test systems (ESNATS)' European commission research project established RT tests based on defined differentiation protocols of hESC and their progeny. Valproic acid (VPA) and methylmercury (MeHg) were used as positive control compounds to address the following fundamental questions: (1) Does transcriptome analysis allow discrimination of the two compounds? (2) How does analysis of enriched transcription factor binding sites (TFBS) and of individual probe sets (PS) distinguish between test systems? (3) Can batch effects be controlled? (4) How many DNA microarrays are needed? (5) Is the highest non-cytotoxic concentration optimal and relevant for the study of transcriptome changes? VPA triggered vast transcriptional changes, whereas MeHg altered fewer transcripts. To attenuate batch effects, analysis has been focused on the 500 PS with highest variability. The test systems differed significantly in their responses (\20 % overlap). Moreover, within one test system, little overlap between the PS changed by the two compounds has been observed. However, using TFBS enrichment, a relatively large 'common response' to VPA and MeHg could be distinguished from 'compound-specific' responses. In conclusion, the ESNATS assay battery allows classification of human DNT/RT toxicants on the basis of their transcriptome profiles.EU/FP7/ESNATSDFGDoerenkamp-Zbinden Foundatio