648 research outputs found
Synthesis, Characterization, and Fabrication of All Inorganic Quantum Dot LEDs
Quantum Dot LEDs with all inorganic materials are investigated in this thesis. The research was motivated by the potential disruptive technology of core shell quantum dots in lighting and display applications. These devices consisted of three main layers: hole transport layer (HTL), electron transport layer (ETL), and emissive layer where the emission of photons occurs. The latter part was formed of CdSe / ZnS core-shell quantum dots, which were synthesized following hot injection method. The ETL and the HTL were formed of zinc oxide nanocrystals and nickel oxide, respectively. Motivated by the low cost synthesis and deposition, NiO and ZnO were synthesized following sol-gel method and deposited using spin coating. The anode of the device was a commercial slide of indium tin oxide deposited on glass substrate while the cathode was a 100 nm aluminum layer that was deposited using an Auto 306T Edwards thermal evaporator.
In this research, Raman spectroscopy, micro-photoluminescence spectroscopy, absorbance spectroscopy, X-ray diffraction (XRD) spectroscopy, and atomic force microscopy, were used to characterize the materials. Three sharp peaks were observed in the XRD measurements of the NiO thin film related to three planes and indicated a proper level of crystallinity. The AFM image of the same material indicated a roughness RMS value of 2 nm which was accepted for a device fabrication.
The photoluminescence spectrum exhibited a peak at 515 nm for the quantum dots and a peak at 315 nm for the ZnO nanocrystals. The narrow shape of these spectra proved a limited amount of size variation. The transfer characteristics of the fabricated device indicated that the current density ramped up producing green light when the voltage was higher than 5 V to reach 160 mA cm-2 at 9 V
Catalytic upgrading of hydrothermal liquefaction biocrudes: Different challenges for different feedstocks
Hydrothermal liquefaction (HTL) followed by catalytic hydrotreating of the
produced biocrude is increasingly gaining ground as an effective technology for
the conversion of biomass into liquid biofuels. A strong advantage of HTL
resides in its great flexibility towards the feedstock, since it is able to
treat a large number of different organic substrates, ranging from dry to wet
residual biomass. Nevertheless, the characteristics of biocrudes from different
typologies of organic materials result in different challenges to be met during
the hydrotreating step, leading to differences in heteroatoms removal and in
the typology and composition of the targeted products. In this work, biocrudes
were catalytically hydrotreated with a commercial NiMo/Al2O3 catalyst at
different temperatures and pressures. Sewage sludge biocrude was found to be
very promising for the production of straight-chain hydrocarbons in the diesel
range, with considerable heteroatoms removal even at mild hydrotreating
conditions. Similar results were shown by algal biocrude, although complete
denitrogenation is challenging. Upgraded biocrudes from lignocellulosic
feedstock (miscanthus) showed high yields in the gasoline range, with a
remarkable content of aromatics. Operating at a higher H2 pressure was found to
be crucial to prevent coking and decarboxylation reactions.Comment: Accepted manuscript for publication in Renewable Energ
Numerical simulation of integrating an air conditioner with an evaporative air cooler
During the summer, air conditioning is increasingly used in commercial and residential structures to provide thermal comfort. The elevated condenser pressure caused by high ambient temperatures has led to a significant increase in electricity consumption in dry, hot climates. Therefore, this article presents the results of a numerical simulation investigation into the feasibility of enhancing the performance of a conventional air conditioning unit by applying a direct evaporative cooling system. The objective is to increase the cooling capacity while decreasing power consumption. The program used a small window-type air conditioner configured to simulate various weather conditions. The numerical findings indicate that incorporating evaporative cooling aids improved the system's ability to overcome numerous obstacles, resulting in a 10–20% increase in refrigeration capacity. Additionally, power consumption was reduced by approximately 3%, and the discharge temperature fell by 6–10°C. The predicted mean vote standard (PMV) for thermal conditions for human occupants yielded favorable outcomes (normal-type). Despite the challenging climate conditions prevailing during the five sweltering summer months, water production demonstrated good results, particularly in September
Library of Congress Classification (LCC): past, present and its future in the digital era
This article describes the various aspects of LC Classification and its suitability as a library classification system for classifying library resources in India. It begins with an introduction, recounting its history and development, leading up to an explanation of principles, structure, tables, and notation. This is followed by number building examples for subjects specific to Indian context, such as the history of Hindi literature with MARC 21 coding for LCC numbers.LCC tools and aids are listed thereafter with a description of the use of technology for efficient and consistent number building, and the process of proposing new numbers online to be added to the LCC schedules. Finally, analysing both its advantages and criticisms it concludes that LCC is a suitable classification system for libraries in India
Early Phase Disease Modification Trials with Selisistat & Optical Coherence Tomography as a Biomarker in Huntington's Disease
Huntington’s disease (HD) is a monogenic neurodegenerative disorder with no known cure. Selisistat is a novel, highly potent Sirt1 inhibitor with supportive pre-clinical data. Facilitation of autophagy and amelioration of transcriptional dysregulation are proposed as mechanisms of action. A first in disease Phase 1B study showed safety and tolerability. The peripheral immune dysfunction in HD could be modulated by Sirtuins which have both pro and anti-inflammatory activities. However selisistat did not alter the cytokine profile in this study. Phase 2 data over a longer duration was also well tolerated however potential hepatotoxicity is a concern. Sub-analysis of clinical assessments did not reveal any significant effect. Confirmation of proposed mechanisms of action is lacking and no Phase III studies are planned. Significant clinical heterogeneity exists in HD phenotypes which must reflect differing neuronal susceptibilities. A novel total motor score based sub-division of HD phenotypes failed to demonstrate any changes in a whole brain voxel-based morphometry (VBM) analysis. Clinical assessment alone lacks sensitivity over shorter time-spans in HD, and thus reliable, tolerable and sensitive biomarkers are required. Optical coherence tomography is a potential novel biomarker. The hypothesis that neuroretinal structures may be surrogate marker of intracranial disease was tested in a pilot biomarker study, the first of its kind in HD. Evidence of a statistically significant (p < 0.01) reduction in macular volume in HD subjects versus age and sex-matched controls is seen. No change in RFNL measures was seen. A correlation with increasing disease severity on ordinal regression was also noted. No correlation of macular volume and RNFL thickness with change in whole brain and caudate volumes. Furthermore, OCT was well tolerated by the majority of participants. Retinal abnormalities in HD have been confirmed in three subsequent independent OCT studies
Frequency of Adverse Maternal and Neonatal Outcomes in Patients with Low Serum Fibrinogen Level and Placental Abruption
Objective: To assess frequency of adverse maternal and neonatal outcomes in patients with low serum fibrinogen level and placental abruption.Place and duration: It was held in Gynecology Department Nishtar Hospital Multan from 12 November 2017 to 25 July 2018.Study Design: Case control retrospective study.Methodology: A total of 100 patients were included in this clinical trial and they were diagnosed with placental abruption. They were categorized on the basis of serum fibrinogen level into three groups; high fibrinogen group (400-600 mg/dL), normal fibrinogen group (300-400 mg/dL) and low fibrinogen group (<200 mg/dL). . The pregnant women with uterine rupture, wound of birth canal, placental accrete, placental praevia, HELLP syndrome, severe preeclampsia, monochorionic multiple pregnancies, major fetal anomalies and sign of intrauterine infection were excluded and all other women with single or more pregnancies were eligible for this clinical study. Computer software SPSS version 23.2 was used for entering and analyzing data. Frequency and percentage was calculated for baseline variables. Frequency and percentage was calculated for laboratory parameters. Frequencies and percentage was calculated for maternal and neonatal outcome variables like mode of delivery, PIH, GDM A, postpartum hemorrhage (PPH), postpartum anemia (PPA), FFP and RCC transfusion, ISTH DIC score, delay discharge from hospital, fetal death, Apgar score at 5 min <7, birth weight, still birth, umbilical artery pH < 7.00, neonatal gestational age and IUFG. ANOVA test was used to find frequency and percentage. P value was < 0.05 was considered to be significant.Result: 100 patients were included in this study and they were divided on the basis of serum fibrinogen level into three groups i.e. n=40 high Fibrinogen group (400-600 mg/dL), n=35 normal Fibrinogen group (300-400mg/dL) and n=25 low Fibrinogen group (<200mg/dL). All the data recorded from all three groups regarding PIH, GDM, FFP, RCC transfusion, ISTH DIC score, delayed discharge from hospital was insignificant. The differences were statistically significant of postpartum hemorrhage PPH (p=0.001) and postpartum anemia PPA (p=0.002). The data recorded from three groups regarding, Apgar score at 5 min <7, Birth weight (g), Umbilical artery pH < 7.00 and intrauterine fetal growth was statistically insignificant. The statistical differences observed in three groups were as; fetal death (p=0.047), still birth (p=0.016), and gestational age (weeks) (p= 0.001) respectively.Conclusion: It has been concluded that low serum fibrinogen level has higher frequency of adverse maternal and neonatal outcomes including postpartum hemorrhage (PPH), postpartum anemia (PPA), fetal death, small gestation age of neonates and still birth than normal and high serum fibrinogen level. Keywords: Low serum fibrinogen, Placental Abruption, Maternal, Neonatal outcomes
Two-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous hydrothermal liquefaction: A rational design of the stabilization stage
Effective catalytic hydrotreatment of highly nitrogenous biocrudes derived
from the hydrothermal liquefaction (HTL) of primary sewage sludge and microalga
Spirulina biomass was explored. A critical issue is the lack of thermal
stability of raw HTL biocrudes at the severe conditions (~400 {\deg}C) required
for hydrodenitrogenation. This fact suggests the need for a two-stage approach,
involving a first low-temperature stabilization stage followed by another one
operated at higher temperature. In this study, DSC was successfully used to
indicate the thermal stability of both biocrudes. During hydrotreating, it was
observed that complete deoxygenation was already achieved in the first stage at
350 {\deg}C, with limited coke formation. Moreover, after second stage up to
92% denitrogenation associated with the higher hydrogen consumption (39.9 g kg
-1 for Spirulina and 36.9 g kg -1 for sewage sludge) was obtained for both
biocrudes. Consequently, comparable oil yields but significantly less coke
yields were recorded during two stage upgrading (1.0% for Spirulina and 0.7%
for sewage sludge), compared to direct processing at 400 {\deg}C (9.1% for
Spirulina and 3.4% for sewage sludge). In addition, the properties of the
upgraded oils were enhanced by increasing the temperature in the first stage
(310 {\deg}C, 330 {\deg}C and 350 {\deg}C respectively). Finally, the results
indicated that remarkable drop in fuel properties were obtained, with respect
to heteroatom (O and N) removal, HHV, and H/C ratio during the two stage
hydrotreatment. Two-stage hydrotreating is therefore proposed as a successful
approach for the upgrading of HTL biocrudes with high nitrogen content.Comment: Accepted manuscript. Published in Biomass & Bioenergy (Elsevier
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