94 research outputs found
Prediction of tool temperature during machining of Ti-6Al-4V alloy with atomization-based cutting fluid spray system
No full textAtomization-based cutting fluid (ACF) spray system is being sought as an alternative to cooling processes currently used for machining difficult-to-cut materials such as Ti-6Al-4V alloy. The ACF spray system generates a stream of monodispersed droplets of cutting fluid which then gets mixed in a high-velocity gas flow to form a focused axisymmetric jet of droplets. During machining, this jet is able to penetrate the small region of the tool-chip interface helping in lubrication and cooling of the interface. The advantage of the ACF spray system is that it requires very small amount of cutting fluid, which makes the system more energy efficient and environmentally friendly. It has been recently reported that ACF spray system improves machining performances including tool life and reduced temperature near the tool-chip interface in turning Ti-alloy. It is clear from these studies that the reduction in temperature and improvement in machining are mainly dependent on the interaction of the cutting fluid from the ACF spray system with the chip-tool interface. Therefore, it is imperative to have a physics-based understanding of the phenomena taking place at the interface that is responsible for the tool temperature reduction.
In this study, a thermal model for the atomization-based cutting fluid (ACF) spray system is developed to predict the temperature of the cutting edge of the tool during machining of titanium alloys. In the model, film boiling is taken into account because of the high temperatures involved in turning of Ti-6Al-4V alloy. Due to film boiling a thin vapor film is formed between the heated tool surface and the droplet. Heat is being conducted away from the tool through this film. It is shown that the thermal model is able to predict the temperature reduction due to ACF spray cooling and the predicted temperature profile is comparable to the experimental results.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-08-01The student, Asif Tanveer, accepted the attached license on 2015-07-24 at 11:26.The student, Asif Tanveer, submitted this Thesis for approval on 2015-07-24 at 11:34.This Thesis was approved for publication on 2015-07-24 at 12:56.DSpace SAF Submission Ingestion Package generated from Vireo submission #8643 on 2015-09-29 at 15:06:54Made available in DSpace on 2015-09-29T21:08:27Z (GMT). No. of bitstreams: 2
TANVEER-THESIS-2015.pdf: 5086790 bytes, checksum: 282d1e7303cadf265c50b5554666401f (MD5)
LICENSE.txt: 4209 bytes, checksum: bd7acda06591d0aee5bc8c7fd43c53f5 (MD5)
Previous issue date: 2015-07-24Embargo set by: Seth Robbins for item 89602
Lift date: 2017-09-29T21:08:35Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 89602 on 2017-09-30T09:15:32Z
The role of moderate Muslims in combating violent Jihad
No full texts can play their most useful role only after the state is able to contain the radicals and secure conditions that are congenial for views different from those of radicals to be expressed.Approved for public release; distribution is unlimited.India Ministry of Defense author (civilian).http://archive.org/details/theroleofmoderat10945301
Effects of Crop Management Systems On Weed Abundance and Soil Seed Bank
No full textGiven the importance of different weed management systems (MS) for weed communities and soil seed bank, our aim was to study the impacts of organic (Org) and conventional (Conv) MS in tomato and sugar beet on the abundance of weeds and weed seed bank. The results have shown that in both crops the aboveground weed flora is dominated by 2–3 species in the Conv MS, while it is more diverse in the Org MS. In both crops the soil seed bank is less diverse when compared with the aboveground weed flora. Furthermore, a comparative analysis of the weed flora and soil seed bank has shown a high number of different weed seeds in the soil for tomato, unlike sugar beet, where a higher number of weeds was determined in the aboveground weed flora. In tomato, the soil seed bank is more diverse in Org MS (4.1 ± 1.5) than in Conv MS (3.8 ± 1.3), which was also true for the aboveground plant biodiversity (4.6 ± 1.1 vs. 3.6 ± 1.5 species, respectively). Also, although the differences in aboveground weed density and abundance in tomato were not statistically significant, seed bank reserves in the Org MS were significantly more abundant (40.4 ± 16.7 weed seeds vs. 4.5 ± 3.6 in Conv MS). This study has also shown that in sugar beet there were practically no differences between Org and Conv MS, even though the abundance of its aboveground weed flora was higher in Org MS (70.2 ± 29.4 vs. 38.1 ± 21.2 plants/m2 in Conv MS). In conclusion, it can be said that although both MS had similar effects on weed management in tomato, for sugar beet Org MS has proven to be less effective in weed control. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Deutschland, part of Springer Nature
A simulation framework for bio-inspired sonar sensing with Unmanned Aerial Vehicles
No full text© 2020 Tanveer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. We introduce a unified simulation framework that generates natural sensing environments and produces biosonar echoes under various sensing scenarios. This framework produces rich sensory data with environmental information completely known, thus can be used for the training of robotic algorithms for biosonar-based Unmanned Aerial Vehicles. The simulated environment consists of random trees with full geometry of the tree foliage. To simulate a single tree, we adopt the Lindenmayer system to generate the initial branching pattern and integrate that with the available measurements of the 3D computer-aided design object files to create natural-looking branches, sub-branches, and leaves. A forest is formed by simulating trees at random locations generated by using an inhomogeneous Poisson process. While our simulated environments can be generally used for testing other sensors and training robotic algorithms, in this study we focus on testing bat-inspired Unmanned Aerial Vehicles that recreate bat’s flying behavior through biosonar sensors. To this end, we also introduce an foliage echo simulator that produces biosonar echoes while mimicking bat’s biosonar system. We demonstrate the application of the proposed simulation framework by generating real-world scenarios with multiple trees and computing the resulting impulse responses under static or dynamic motions of an Unmanned Aerial Vehicle
Diagnosis of hepatoma using grayscale and Doppler ultrasound in patients with chronic liver disease
No full textWasim A Memon, Zishan Haider, Mirza Amanullah Beg, Muhammad Idris, Tanveer-ul-Haq, Waseem Akhtar, Sidra IdrisRadiology Department, Aga Khan University Hospital, Karachi, Pakistan Every author contributed equally to the workObjective: To determine the diagnostic accuracy of liver ultrasound for the detection of hepatoma in chronic liver disease (CLD) patients by either taking histopathology or serum α-fetoprotein levels or a biphasic computed tomography (CT) scan (whichever is available) as the gold standard.Study design: Cross-sectional.Place and duration of study: Radiology Department, The Aga Khan University Hospital, Karachi, Pakistan, from January 2007 to January 2010.Methods: A total of 239 patients (156 males and 83 females) with clinical suspicion or surveillance of hepatoma in CLD referred to the radiology department for ultrasound evaluation followed by either liver biopsy and histopathology or serum α-fetoprotein level or biphasic CT scan.Results: The sensitivity of ultrasound for hepatoma detection in CLD was 65%, specificity was 85%, and accuracy was 70%, and positive predictive value and negative predictive value were 92% and 45%, respectively.Conclusion: Ultrasound is a relatively quick, safe, reasonably accurate, and noninvasive imaging modality for the detection of hepatoma in CLD and can be complemented with clinical assessment of screening high-risk patients.Keywords: hepatoma, ultrasound, radiology, chronic liver diseas
A Case Report on Pancoast Tumor
No full textTo present and discuss a case of Pancoast Tumor: an apical lung neoplasm, and subsequentlyhighlight the clinical importance of chronic and progressive complaints, pertaining to this pathology,in helping to detect it and form an early diagnosis.Case: A 55-year-old non-smoker male patient, with a known case of gout and uncontrolled diabetesmellitus, presented to emergency with complaints of severe right-sided pain in the chest, subscapularand axillary regions. His electrocardiogram (ECG) and cardiac enzyme came out to be normal. ChestX-ray showed an opacity in the apex of the right lung. On contrast-enhanced computed tomography(CECT), there were enhancing multi-focal lesions in the apical segment of the right lung making adiagnosis of Pancoast tumor.Even though, it may be missed in the early stages as the tumor cannot be seen on imaging investigationsand biopsy is more specific at this time, imaging studies do play a substantial role in diagnosing thistumor. Due to the challenges in diagnosing this rare type of lung neoplasm, it is usually diagnosedwhen it has locally invaded.Conclusion: Awareness regarding clinically important warning signs of Pancoast tumors such aschronic and progressive neck and shoulder pain can help healthcare professionals, most notably butnot exclusively, chiropractors, in prompt identification of these signs and symptoms, thus facilitatinga timely medical and/or surgical referral and an early diagnosis of this pathology. A thoroughexamination can assist in early diagnosis and lead to a subsequent decrease in mortality and animprovement in quality of life.Keywords: Pancoast syndrome, Neck pain, Lung neoplasms
MHC-I ligand discovery using targeted database searches of mass spectrometry data: Implications for T-cell immunotherapies
No full textClass I major histocompatibility complex (MHC-I)-bound peptide ligands dictate the activation and specificity of CD8+ T cells and thus are important for devising T-cell immunotherapies. In recent times, advances in mass spectrometry (MS) have enabled the precise identification of these MHC-I peptides, wherein MS spectra are compared against a reference proteome. Unfortunately, matching these spectra to reference proteome databases is hindered by inflated search spaces attributed to a lack of enzyme restriction in the searches, limiting the efficiency with which MHC ligands are discovered. Here we offer a solution to this problem whereby we developed a targeted database search approach and accompanying tool SpectMHC, that is based on a priori-predicted MHC-I peptides. We first validated the approach using MS data from two different allotype-specific immunoprecipitates for the C57BL/6 mouse background. We then developed allotype-specific HLA databases to search previously published MS data sets of human peripheral blood mononuclear cells (PBMCs). This targeted search strategy improved peptide identifications for both mouse and human ligandomes by greater than 2-fold and is superior to traditional “no enzyme” searches of reference proteomes. Our targeted database search promises to uncover otherwise missed novel T-cell epitopes of therapeutic potential
Study of surface mechanical characteristics of abs/pc blends using nanoindentation
No full textAcrylonitrile butadiene styrene (ABS) and polycarbonate (PC) are considered a well-known class of engineering thermoplastics due to their efficient use in automotive, 3D printing, and elec-tronics. However, improvement in toughness, processability, and thermal stability is achieved by mixing together ABS and PC. The present study focuses on the understanding of surface mechanical characterization of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) blends using nano-indentation. Polymer blends sheets with three different proportions of ABS/PC (75:25, 50:50, and 25:75) were fabricated via melt-processing and thermal press. Fourier transform infrared (FTIR) spectroscopy was performed to analyze the intermolecular interactions between the blends’ compo-nents. To understand the surface mechanical properties of ABS and PC blends, a sufficient number of nano-indentation tests were performed at a constant loading rate to a maximum load of 100 mN. Creeping effects were observed at the end of loading and start of unloading section. Elastic modulus, indentation hardness, and creep values were measured as a function of penetration displacement in the quasi-continuous stiffness mode (QCSM) indentation. Load-displacement curves indicated an increase in the displacement with the increase in ABS contents while a decreasing trend was observed in the hardness and elastic modulus values as the ABS content was increased. We believe this study would provide an effective pathway for developing new polymer blends with enhanced mechanical performance.Aerospace Manufacturing Technologie
Autophagic homeostasis is required for the pluripotency of cancer stem cells
No full textPluripotency is an important feature of cancer stem cells (CSCs) that contributes to self-renewal and chemoresistance. The maintenance of pluripotency of CSCs under various pathophysiological conditions requires a complex interaction between various cellular pathways including those involved in homeostasis and energy metabolism. However, the exact mechanisms that maintain the CSC pluripotency remain poorly understood. In this report, using both human and murine models of CSCs, we demonstrate that basal levels of autophagy are required to maintain the pluripotency of CSCs, and that this process is differentially regulated by the rate-limiting enzyme in the NAD+ synthesis pathway NAMPT (nicotinamide phosphoribosyltransferase) and the transcription factor POU5F1/OCT4 (POU class 5 homeobox 1). First, our data show that the pharmacological inhibition and knockdown (KD) of NAMPT or the KD of POU5F1 in human CSCs significantly decreased the expression of pluripotency markers POU5F1, NANOG (Nanog homeobox) and SOX2 (SRY-box 2), and upregulated the differentiation markers TUBB3 (tubulin β 3 class III), CSN2 (casein β), SPP1 (secreted phosphoprotein 1), GATA6 (GATA binding protein 6), T (T brachyury transcription factor) and CDX2 (caudal type homeobox 2). Interestingly, these pluripotency-regulating effects of NAMPT and POU5F1 were accompanied by contrasting levels of autophagy, wherein NAMPT KD promoted while POU5F1 KD inhibited the autophagy machinery. Most importantly, any deviation from the basal level of autophagy, either increase (via rapamycin, serum starvation or Tat-beclin 1 [Tat-BECN1] peptide) or decrease (via ATG7 or ATG12 KD), strongly decreased the pluripotency and promoted the differentiation and/or senescence of CSCs. Collectively, these results uncover the link between the NAD+ biosynthesis pathway, CSC transcription factor POU5F1 and pluripotency, and further identify autophagy as a novel regulator of pluripotency of CSCs
Fabrication and Nanomechanical Characterization of Thermoplastic Biocomposites Based on Chemically Treated Lignocellulosic Biomass for Surface Engineering Applications
No full textDiverse applications of polymeric materials have prompted development of eco-friendly, efficient, and economical materials. These characteristics can be obtained by incorporating appropriate fillers in the polymeric matrix. The objective of this work is to investigate impact of aqueous glycerol (Gly) treated rice husk (RH) on surface mechanical properties of produced biocomposites. RH was treated with aqueous Gly (75 wt%) and compounded with low density polyethylene (LDPE) at different loadings (10, 20, and 30 wt%). The resulting mixture was thermally pressed in molds to fabricate biocomposites. Surface mechanical properties such as elastic modulus, hardness, creep rate, and plasticity of biocomposites reinforced with untreated and treated RH were investigated using nanoindenter. Experimental values depicted that hardness (H) and elastic modulus (Es) of treated biocomposites were higher than untreated ones. Treated biocomposites showed the noticeable improvement in elastic modulus by 24 and 37% compared to untreated biocomposites at 20 wt% loading and neat LDPE, respectively. Reductions in the creep rate by 20 and 14% were observed for untreated and treated biocomposites, respectively, in comparison to the neat LDPE. H/E ratio was increased by 23 and 18% for treated and untreated biocomposites, respectively, as compared to virgin LDPE. Furthermore, mechanical and structural properties of untreated and treated RH are reported based on nanoindentation response and Fourier transform infrared spectroscopy (FTIR) techniques The study indicated that aqueous glycerol pretreatment can partially strip off non-cellulosic constituents from lignocellulose matrix to generate cellulose-rich pulp for engineered composite applications.Rivers, Ports, Waterways and Dredging Engineerin
- …
