92 research outputs found
Synthesis and Characterization of Kesterite Cu2ZnSnS4 (CZTS) Thin Films for Solar Cell Application
The quaternary compound Cu2ZnSnS4 (CZTS) gained considerable attention in the last decade due to its potential as an active-layer semiconductor for low-cost thin-film solar cells. The material is composed of nontoxic and Earth-abundant constituents, has optical properties suitable for photovoltaic application, and can be synthesized using a wide variety of methods.
Polycrystalline CZTS was grown in this work using vacuum-based deposition to first deposit metal films (precursors) of Cu, Zn, and Sn. In a subsequent step, the precursors underwent an annealing treatment in sulfur vapor environment (sulfurization) to form CZTS. Using sputtering, a physical vapor deposition (PVD) technique, two different kinds of metal precursors were deposited: a) stacked precursors, in which a stack of metal layers are sequentially deposited on a glass substrate, and b) co-sputtered precursors, in which the three metals are deposited simultaneously.
The effect of sulfurization time and temperature was investigated to optimize the process and to study the impact of both factors on the morphological and structural properties of the synthesized compound. CZTS films based on a stacked precursor were prepared and characterized by X-ray fluorescence, energy-dispersive X-ray spectroscopy, electron probe microanalysis, X-ray diffraction, scanning electron microscopy , ultraviolet-visible-near-infrared spectrophotometry, and Auger electron spectroscopy. Films with dense morphology, good crystallinity, and optical energy bandgap close to 1.5 eV were obtained using annealing temperatures of 500 °C and 550 °C. Furthermore, the study addressed the issue with Cu2-xS phases segregated on the film surface and suggested a route to avoid their evolution.
The secondary-phase dependence on the chemical composition was studied, focusing on suppressing Cu2-xS phases. In addition, we addressed the importance of Sn/Cu ratio as a controlling factor to avoid developing these detrimental phases. An electron backscatter diffraction study confirmed the role of increased Cu content in achieving larger grains.
Studying the influence of the stack sequence in the precursor revealed that depositing Zn as the first or second layer leads to better adhesion, and depositing Cu as top layer minimizes the loss of Sn and allows better control of film composition. Solar cells based on CZTS films prepared with the sulfurization of precursors with different stacking orders were produced, and the best device showed power conversion efficiency (PCE) of 4.43%.
CZTS films based on co-sputtered precursors showed very promising results in terms of large grains, dense morphology, and smooth surface; however, they suffered from poor adhesion to the Mo layer due to compressive intrinsic stresses. Further investigation is needed to identify the stress origin and improve the contact to the back electrode. The best device based on CZTS films from co-sputtered precursors yielded a PCE of 1.72%
Gaussian Process Adaptive Soft Sensors and their Applications in Inferential Control Systems
building. This research reviews the use of this technique
as an adaptive soft sensor building method. It investigates different model structures, addresses issues associated with this technique, introduces Gaussian
process-based soft sensors in inferential control, and proposes a methodology to enhance the reliability of the introduced inferential control system. These are achieved by conducting various case studies and empirical experiments on real and artificial data retrieved from real and simulated industrial processes. The comparative case studies conducted on various Gaussian process model structures revealed that the Matern class covariance functions outperform the predominantly used squared exponential functions, particularly in clean and properly pre-processed data sets. The results show the plausibility of Gaussian processes in building adaptive soft sensors, particularly those based on windowing techniques. Specifically, empirical results have revealed that the prediction accuracy of the sensor can be improved by considering window-updating criteria. The research results have also shown that the size of raw data used for soft sensor development can be significantly reduced while preserving the informative properties of the data. This results in a significant reduction in the associated computational cost of Gaussian process-based models. Simulated results have also revealed that an adaptive soft sensor with a high prediction capability can be integrated with Proportional Integral controllers to build inferential control systems. The robustness and reliability of such a control system can be enhanced using a hybrid Gaussian process and kernel Principle Component Analysis-based method. This allows the implementation of the control system in the industrial process during both healthy and faulty operating conditions
Urinothorax Caused by Xanthogranulomatous Pyelonephritis
Xanthogranulomatous pyelonephritis is a rare form of chronic pyelonephritis that generally afflicts middle-aged women with a history of recurrent urinary tract infections. Its pathogenesis generally involves calculus obstructive uropathy and its histopathology is characterized by replacement of the renal parenchyma with lipid filled macrophages. This often manifests as an enlarged, nonfunctioning kidney that may be complicated by abscess or fistula. This case details the first reported case of xanthogranulomatous pyelonephritis complicated by urinothorax, which resolved on follow-up chest X-ray after robot-assisted nephrectomy
Small Cell Carcinoma of Prostate: A Case Report of a Patient With Concomitant Transitional Cell Cancer of the Bladder
Small cell carcinomas (SCCs) are aggressive neoplasms commonly associated with a pulmonary origin. However, albeit rare, extrapulmonary SCC can occur in a variety of sites with an incidence in North America approximated to be 0.1% to 0.4%. Among these sites, approximately 10% of extrapulmonary SCC cases occur in the prostate and are associated with a poor mortality with a median survival of 10 months. Because of the rarity of the prostatic SCC, there is no formal treatment protocol. In this case report, we present a patient who was diagnosed with SCC in the prostate as primary origin. Adjuvant concurrent chemoradiotherapy was started, which he is tolerating so far. While the management of metastatic disease is well documented with the use of chemotherapy, specific data on nonmetastatic disease is lacking. As some studies suggest, a combined surgical and chemotherapeutic approach is helpful in localized disease. In our case, this approach has led to a good clinical outcome in a disease that does not usually allow such results
Percutaneous Transluminal Balloon Venoplasty: A Less Invasive Technique for Implantation of Cardiac Leads in Patients with Limited Venous Access to the heart
Since its inception, cardiac pacing has made a significant advancement in cardiology. As new therapies and devices emerge, the number of implantations is steadily increasing which requires up-to-date clinical guidelines for management. Although advanced, these mechanical devices often require maintenance and revisions to achieve optimal performance. One of the most common deteriorations is the lead failure.
In the case of lead failure requiring revision, new lead implant, or upgrading to a more advanced pacing system, venous stenosis resulting in partial or complete obstruction of the vessel can pose a real problem. This case series report introduces the technique of percutaneous transluminal balloon venoplasty in the setting of venous stenosis as an alternative to more invasive procedures such as lead extraction for lead revision or device upgrade
Percutaneous Transluminal Balloon Venoplasty: A Less Invasive Technique for Implantation of Cardiac Leads in Patients with Limited Venous Access to the heart
Since its inception, cardiac pacing has made a significant advancement in cardiology. As new therapies and devices emerge, the number of implantations is steadily increasing which requires up-to-date clinical guidelines for management. Although advanced, these mechanical devices often require maintenance and revisions to achieve optimal performance. One of the most common deteriorations is the lead failure.
In the case of lead failure requiring revision, new lead implant, or upgrading to a more advanced pacing system, venous stenosis resulting in partial or complete obstruction of the vessel can pose a real problem. This case series report introduces the technique of percutaneous transluminal balloon venoplasty in the setting of venous stenosis as an alternative to more invasive procedures such as lead extraction for lead revision or device upgrade
MODEL PEMBELAJARAN BAHASA INDONESIA BERBASIS LESSON STUDY ( MODEL-PBIBLS)
Buku model ini berisikan teori-teori yang mendukung pengembangan model pembelajaran bahasa Indonesia berbasis lesson study. Model pembelajaran bahasa Indonesia berbasis Lesson Study merupakan salah satu bentuk dari praktik belajar bahasa Indonesia, yaitu suatu inovasi pembelajaran yang dirancang untuk membantu peserta didik memahami konsep-konsep, prinsip-prinsip, teori-teori bahasa Indonesia secara mendalam melalui pengalaman belajar praktik-empirik secara kolaborasi antara siswa dengan siswa, siswa dengan guru, dan guru dengan guru
A systematic review and meta-analysis of the impact of the left atrial appendage closure on left atrial function.
BACKGROUND: Left atrial (LA) appendage closure (LAAC) is effective in patients with atrial fibrillation who are not candidates for long-term anticoagulation. However, the impact of LAAC on LA function is unknown. The aim of this study is to evaluate the impact of LAAC on atrial function. METHODS: This meta-analysis was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A search strategy was designed to utilize PubMed/Medline, EMBASE, and Google scholar for studies showing the effect of LAAC on the LA function from inception to November 20, 2021. The standardized mean difference (SMD) was calculated from the means and standard deviations. RESULTS: Of 247 studies initially identified, 8 studies comprising 260 patients were included in the final analysis. There was a significant increase in LA emptying fraction following LAAC compared with preoperative function (SMD: 0.53; 95% confidence interval [CI]: 0.04-1.01; p = .03; I2  = 75%). In contrast, there were no significant differences in LA volume (SMD: -0.07; 95% CI: -0.82-0.69; p = .86; I2  = 92%) peak atrial longitudinal strain (SMD: 0.50; 95% CI: -0.08-1.08; p = .09; I2  = 89%), peak atrial contraction strain (SMD: 0.38; 95% CI: -0.22-0.99; p = .21; I2  = 81%), strain during atrial contraction (SMD: -0.24; 95% CI: -0.61-0.13; p = .20; I2  = 0%), strain during ventricular systole (SMD: 0.47; 95% CI: -0.32-1.27; p = .24; I2  = 89%), strain during ventricular diastole (SMD: 0.09; 95% CI: -0.32-0.51; p = .66; I2  = 65%). CONCLUSION: LAAC is associated with improvement in the left atrial emptying fraction, but did not significantly influence other parameters
Induction of apoptosis by thymoquinone in lymphoblastic leukemia Jurkat cells is mediated by a p73-dependent pathway which targets the epigenetic integrator UHRF1
PloS one
The vasculoprotective properties of delphinidin are driven mainly by its action on endothelial cells. Moreover, delphinidin displays anti-angiogenic properties in both in vitro and in vivo angiogenesis models and thereby might prevent the development of tumors associated with excessive vascularization. This study was aimed to test the effect of delphinidin on melanoma-induced tumor growth with emphasis on its molecular mechanism on endothelial cells. Delphinidin treatment significantly decreased in vivo tumor growth induced by B16-F10 melanoma cell xenograft in mice. In vitro, delphinidin was not able to inhibit VEGFR2-mediated B16-F10 melanoma cell proliferation but it specifically reduced basal and VEGFR2-mediated endothelial cell proliferation. The anti-proliferative effect of delphinidin was reversed either by the MEK1/2 MAP kinase inhibitor, U-0126, or the PI3K inhibitor, LY-294002. VEGF-induced proliferation was reduced either by U-0126 or LY-294002. Under these conditions, delphinidin failed to decrease further endothelial cell proliferation. Delphinidin prevented VEGF-induced phosphorylation of ERK1/2 and p38 MAPK and decreased the expression of the transcription factors, CREB and ATF1. Finally, delphinidin was more potent in inhibiting in vitro cyclic nucleotide phosphodiesterases (PDEs), PDE1 and PDE2, compared to PDE3-PDE5. Altogether delphinidin reduced tumor growth of melanoma cell in vivo by acting specifically on endothelial cell proliferation. The mechanism implies an association between inhibition of VEGF-induced proliferation via VEGFR2 signalling, MAPK, PI3K and at transcription level on CREB/ATF1 factors, and the inhibition of PDE2. In conjunction with our previous studies, we demonstrate that delphinidin is a promising compound to prevent pathologies associated with generation of vascular network in tumorigenesis
- …