964 research outputs found
Methodology to Measure the Protective Areal Density of Ceramic Tiles Against Projectile Impact
The protective areal density of any armour material is the important property required for armour design. In this study, ballistic performance of hot pressed boron carbide tiles, with a tile thickness of 12.2 mm, was evaluated using the protective areal density (PAD) test method, against hard steel 12.7 mm armour piercing (AP) projectiles. The binary response data on complete penetration/ partial penetration obtained from PAD testing was fitted with the standard logistic regression model. A detailed discussion on statistical procedure has been presented. The PAD (pp = 0.5) was estimated to be 82.5 kg/m2 and the lower and upper bounds of 95 per cent confidence interval for (PAD) (pp = 0.5) was found to lie between 79.5 kg/m2 and 85.0 kg/m2
Comparison of APACHE II and Imrie Scoring Systems in predicting the severity of Acute Pancreatitis
There has been an increasing amount of work worldwide in search for tests not only to be able to absolutely diagnose acute pancreatitis, but more importantly to prognosticate patients at admission. While the tests are still within the realm of research laboratories and involve complex computing and analytical methods, we believed that the already widely practiced methods of scoring needed to be verified in the Indian context. And, hence, the study
A modified volumetric energy density–based approach for porosity assessment in additive manufacturing process design
Soundness of additively manufactured parts depends on a lot of process and geometrical parameters. A wrong process design leads to defects such as lack of fusion or keyhole porosity that have a detrimental effect on the mechanical properties of the printed parts. Process parameter optimization is thus a formidable challenge that requires in general a huge amount of experimental data. Among the others, heat source power and scan speed are the most defects-affecting parameters to be optimized. The energy density is used in literature to quantify their combination. Unfortunately, in different works it was demonstrated that it fails if used as design parameter mainly because it does not take into account the material properties and the interaction between heat source and the powder bed. In this contribution, a modified volumetric energy density equation that takes into account the powder-heat source interaction to optimize the combination of power-scan speed values for porosity assessment in powder bed fusion process design is proposed and verified on both AlSi10Mg alloy and Maraging steel 300
Ballistic Performance of Alumina and Zirconia-toughened Alumina Against 7.62 Armour Piercing Projectile
A study was carried out to compare the ballistic performance of high purity alumina and zirconia-toughened alumina (ZTA) using depth of penetration (DoP) test configuration against 7.62 mm armour piercing (AP) ammunition. The effect of tile thickness on the differential efficiency factor (DEF) was studied for tile thickness in the range of 3 mm to 6 mm for alumina tiles and 3 mm to 5 mm for ZTA tiles. The DEF is found to increase as tile thickness increases. An analysis on the failed shots showed that the residual shot weight does not follow a single linear relationship with ceramic tile thickness unlike the residual DoP for all thicknesses of tiles. Post-ballistic analysis on ceramic powder for particle size distribution was carried out and the results are presented.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.477-483, DOI:http://dx.doi.org/10.14429/dsj.64.674
The paradigm of norgestimate: a third-generation testosterone-derivative progestin with a peripheral anti-androgenic activity and the lowest risk of venous thromboembolism
Introduction: Norgestimate (NGM) is a testosterone derivative with peculiar receptor activities. Areas covered: This is a narrative review of the available data on the pharmacotherapy of NGM in combined hormonal contraceptives (CHCs) in terms of contraceptive efficacy, venous thromboembolism (VTE) risk, safety, tolerability and bleeding patterns. A comprehensive literature review was conducted in August 2020 using PubMed with the keyword ‘norgestimate’. Expert Opinion: NGM shows a mild estrogenic activity associated with anti-mineralocorticoid and anti-androgenic properties, largely responsible for the cardiovascular safety profile. The anti-androgenic property depends on the androgen receptor (AR) nuclear translocation (AR trafficking and its subnuclear distribution), the inhibition of 5α-reductase activity (it possesses higher activity compared to other available progestins), and the increase on sexual hormone binding globulin (SHBG) levels if combined with an estrogenic counterpart. NGM is one of the molecules that best modulates the power of ethinyl-estradiol on the thromboembolic risk, being associated with the lowest VTE risk between different CHCs. NGM has the advantage of retaining peripheral anti-androgenic activity, demonstrated by the impact on lipid and glucose metabolism, and it should be preferred if compared with other similar progestins of the same class of risk which are much more androgenic, such as levonorgestrel
Eremophila goodwinii F. Muell.
https://thekeep.eiu.edu/herbarium_specimens_byname/21547/thumbnail.jp
Hydrogen induced optically-active defects in silicon photonic nanocavities
This work was supported by Era-NET NanoSci LECSIN project coordinated by F. Priolo, by the Italian Ministry of University and Research, FIRB contract No. RBAP06L4S5 and by the EPSRC UKSp project. Partial financial support by the Norwegian Research Council is also acknowledged.We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.Publisher PDFPeer reviewe
comparison between thermal energy and acoustic emission for the fatigue behavior of steels
Abstract The paper is focused on the study of fatigue materials, using an energy approach, with the support of two different non-destructive techniques. Indeed, the analysis of the energy behavior was conducted by the simultaneous application of Acoustic Emission (AE) and Thermography (TH). The purpose of the paper was to compare and integrate the results obtained by the two methodologies to assess the fatigue behavior of materials. The experimental tests were carried out on flat steel specimens of steels commonly used for metal carpentry either under static loading or under sequences of increasing cyclic loading. The results allow to define the fatigue limit either by the thermography or by the acoustic emission and they are encouraging to continue the comparison and the integration between the two energetic methodologies
Influence of heat-treatment on torsional resistance to fracture of Nickel-Titanium endodontic instruments
AbstractOver the past 3 decades, Nickel-Titanium (NiTi) instruments have become an important part of the armamentarium for shaping phase of root canal treatment. NiTi endodontic files have increased flexibility and strength compared with stainless steel instruments, but they seem to be vulnerable to fracture in clinical situations. Many variables might contribute to file separation, but the 2 main causes are cyclic fatigue and torsional stress. Heat treatment (thermal processing) is one of the most fundamental approaches toward adjusting the transition temperatures of NiTi alloys and affecting the fatigue and torsional resistance of NiTi endodontic files. In recent years, novel thermo-mechanical processing and manufacturing technologies such as controlled memory wire (CM-wire), M-Wire and electrical discharge machining (EDM) have been developed to optimize the microstructure of NiTi alloys and their mechanical properties. Aim of this work was to investigate the torsional resistance (maximum torque load, and angular rotation) of NiTi instruments made by different thermo-mechanical and manufacturing processes.One-hundred new Hyflex EDM One- File (#25/0.08, CM-wire and EDM process), WaveOne Primary (#25/0.08, M-wire), ProTaper Next X2 (#25/0.06, M-wire), Hyflex CM (#25/0.06, CM-wire) and F6 SkyTaper(#25/0.06, conventional NiTi) files were used. Torque and angle of rotation at failure of new instruments (n = 20) were measured using a torsiometer according to ISO 3630-1 for each brand. Data were analyzed using the analysis of variance test and the Student- Newman-Keuls test for multiple comparisons. The fracture surface of each fragment was examined with a scanning electron microscope.Files made by CM wire size #25, 0.06 taper (Hyflex CM) showed same torque load and angular rotation to fracture than conventional NiTi (F6 SkyTaper) (P > .05); instead CM files (manufacturing by grinding or EDM process) recorded lower maximum torque load (P .05) but significantly higher angular rotation (P < .05) to fracture than M-wire instruments size #25, 0.06 taper (ProTaper Next).Hyflex EDM One-File and Hyflex CM have same torque load and angular rotation to fracture than F6 SkyTaper due to the higher flexibility and cross-sectional area of CM files tested than conventional NiTi one.Moreover CM files showed lower torque load and higher angular rotation to fracture than M-wire instruments due to the flexibility of CM alloy. M-wire instruments showed same torque load but significantly lower angular rotation than conventional NiTi files due to the same flexibility and higher cross-sectional area of the files tested
Antimicrobial Peptides Human Beta-Defensin-2 and -3 Protect the Gut During Candida albicans Infections Enhancing the Intestinal Barrier Integrity: In Vitro Study
The intestinal mucosa is composed of a monolayer of epithelial cells, which is highly polarized and firmly united to each other thanks to the presence of proteins complexes, called Tight junctions (TJs). Alteration of the mucus layer and TJs causes an increase in intestinal permeability, which can lead to a microbial translocation and systemic disorders. Candida albicans, in addition to its role of commensal, is an opportunistic pathogen responsible for disseminated candidiasis, especially in immunocompromised subjects where the dysbiosis leads to damage of the intestinal mucosal barrier. In this work, we used a line of intestinal epithelial cells able to stably express the genes that encodes human beta defensin-2 (HBD-2) and -3 (HBD-3) to monitor the invasion of C. albicans in vitro. Defensins are a group of antimicrobial peptides (AMPs) found in different living organisms, and are involved in the first line of defense in the innate immune response against pathogens. The results obtained show that the presence of antimicrobial peptides improves the expression of TJs and increases the Trans Epithelial Electrical Resistence value. In addition, the invasive ability of C. albicans in transfected cells is significantly reduced, as well as the expression levels of genes involved in the apoptotic pathway. Through the study of interaction between antimicrobial peptides and microbiota we will be able in the future to better understand the mechanisms by which they exert the host defense function against intestinal pathogens
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