48 research outputs found
The Predictive Ability of the Dimensions of the Future Time Perspective in Self-regulated Learning among Yarmouk University Students
The study aimed to identify the most common dimensions of the future time perspective and to know the level of self-regulated learning among Yarmouk University students. It also aimed to investigate the predictive ability of the dimensions of the future time perspective in self-regulated learning. The study sample consisted of 704 students, 335 males and 369 females, who were selected based on a convenience sample method from among the students enrolled in the compulsory university requirements during the summer semester of the academic year 2017/2018. To achieve the objectives of the study, the Zimbardo and Boyed’s (1999) measure was used to measure the future time perspective, and Purdie’s scale for measuring self-regulated learning. The results showed that the future dimension was the most common among the sample of the study, and that the level of self-regulated learning was moderate, whether at the total score or the various dimensions. The study concluded that the dimensions of the future time perspective explained 18.8% of the variance in self-regulated learning
Nanomaterials. Effective tools for field and horticultural crops to cope with drought stress: A review
Drought is the most serious environmental challenge that limits plant growth and causes more severe yield losses than other abiotic stress factors resulting in a serious food shortage. Nanomaterials (NMs) are considered as vital tools to overcome contemporary and future challenges in agricultural production. Recently, NMs have been applied for enhancing seed germination, growth, physiology, productivity and quality attributes of various crops under normal or stress conditions. Up to date, there is no a comprehensive review about the potential role of NMs in attenuating the drought-induced adverse effects in crop plants. Thus, this review will highlight this issue. Generally, NMs minimize drought-induced osmotic stress by accumulation of osmolytes that result in osmotic adjustment and improved plant water status. In addition, NMs play a key role to improve root growth, conductive tissue elements and aquaporin proteins facilitating uptake and translocation of water and nutrients. Furthermore, NMs reduce water loss by stomatal closure due to abscisic acid signaling. However, this leads to reduced photosynthesis and oxidative stress damage. At the same time, NMs increase the content of light-harvesting pigments, enzymatic and non-enzymatic antioxidants leading to enhancing photosynthesis with reducing oxidative stress damage. Overall, NMs can ameliorate the deleterious effects of drought stress in crop plants by regulation of gene expression and alternation of various physiological and biochemical processes
The role of climatic-design-operational parameters on combined PV/T collector performance: a critical review
PV/T technology attracted numerous researchers and professionals during the last decades. There are many review papers in the literature evaluated the R&D aspects of PV/T collectors. In fact, there are abundant of case studies discussed the parameters of climate, design and operational conditions affected the PV/T collector performance. But, a comprehensive compilation of the information of those case studies is still a missing link in the literature. Hence, this paper intended to review thoroughly the information regarding the parameters affecting the PV/T collector performance mainly and PV module performance partially. The parameters are supported with the most available R&D to measure the accurate influence of each parameter on the performance. The outcomes from the study are highlighted in lessons learned section
Evaluation of The Economic Efficacy of Some Antimycotoxicosis Compounds on Production and Humoral Immunity in Broiler Chickens.
Mycotoxicosis is an important problem in poultry industry causing global economic losses constituting a great threat. The present study was designed to investigate the ameliorative effects of four different antimycotoxicosis compounds (AMCs) against production, economic performance and humoral immunity induced by intoxication of dietary aflatoxin (AF) and/or ochratoxin (OT) in broiler chicks. Experiment (I), AF (23 ppb) and OT (17 ppb) were fed alone or mixed and in association with antimycotoxin feed additives, product A or B (1 and 0.5 g/kg feed), respectively. In experiment (II), the intoxicated chicks treated with antimycotoxin drugs, product C or D in drinking water (1ml/liter/3 successive days and 0.5 ml/liter/one day), respectively. Results revealed that chicks intoxicated with AF and/or OT showed significant (P<0.05) increase in feed conversion ratio (FCR) and mortality percentages (%) while the antibody titers against Newcastle disease (ND) virus were significantly (P<0.05) reduced. It is interesting to note that the adverse effects on FCR and mortality % were significantly (P<0.05) reduced in the single AF or OT contaminated diets with dietary supplementation of product A but in the mixed AF and OT contaminated diet, FCR were significantly (P<0.05) decreased with addition of product B. Also, product B showed significant (P<0.05) increase in the antibody titers against ND in all AF and/or OT contaminated groups. Moreover, the treatment of AF and/or OT intoxicated chicks with product C or D in the drinking water was reported significant (P<0.05) decrease in the mortality% and non-significant (P>0.05) change in FCR and ND antibody titers
Parametric study on the thermal performance and optimal design elements of solar air heater enhanced with jet impingement on a corrugated absorber plate
Previous works revealed that cross-corrugated absorber plate design and jet impingement on a flat absorber plate resulted in a significant increase in the performance of a solar air heater (SAH). Involving these two designs into one continuous design to improve the SAH performance remains absent in the literature. This study aimed to evaluate the achieved enhancement on performance parameters of a SAH with jet impingement on a corrugated absorber plate. An energy balance model was developed to compare the performance parameters of the proposed SAH with the other two SAHs. At a clear sky day and a mass flow rate of 0.04 kg/s, the hourly results revealed that the max fluid outlet temperatures for the proposed SAH, jet-to-flat plate SAH, and cross-corrugated plate SAH are 321, 317, and 313 K, respectively; the max absorber plate temperatures are 323.5, 326.5, and 328 K, respectively; the maximum temperature differences between the absorber plate and fluid outlet are ~3, 9, and 15 K, respectively; the max efficiencies are 65.7, 64.8, and 60%, respectively. Statistical t -test results confirmed significant differences between the mean efficiency of the proposed SAH and SAH with jet-to-flat plate. Hence, the proposed design is considered superior in improving the performance parameters of SAH compared to other designs
Influence of Raster Angle on Tensile Properties of FDM Additively Manufactured Plates made from Carbon Reinforced PET-G Material
Tensile properties of thin plate specimens made from short carbon fiber
reinforced PET-G material are experimentally evaluated for various raster angles
(printing directions). In additive manufacturing (AM), raster angle is recognized as one
of the key printing parameters which strongly influences the strength and stiffness of the
final part. The relatively high average value of ultimate tensile strength was obtained
for specimens printed with the 0° raster angle, compared to the value obtained for
specimens printed with the 90° raster angle - 52.2 MPa and 25.4 MPa, respectively.
Similarly, noticeably higher average value of modulus of elasticity was obtained for
specimens printed with the 0° raster angle, compared to the value obtained for
specimens printed with the 90° raster angle - 4752 MPa and 1569 MPa, respectively.
Scanning electron microscopy (SEM) was used for analysis of specimens’ fracture
surfaces. SEM images revealed considerable volume fraction of voids (porosity). Тhe
porosity, together with weak bonding between two adjacent rasters, could be one of key
factors for poor tensile properties of samples printed with rasters perpendicular to
direction of load application (90° raster angle
The Impact of Restrictive Versus Conservative Intraoperative Fluid Strategies upon the Renal Outcome in Colorectal Surgeries. A Randomized Controlled Trial
Background: intraoperative fluid handling has a lot of concerns upon the postoperative organ function. One of the most sensitive organs which could be affected is the kidney.
Objectives: We conducted this trial to address the impact of restrictive vs. conservative fluid approaches on postoperative renal complications, hemodynamics and hospital stay.
Patients and methods: Prospective, randomized, double-blind placebo-controlled trial at Assiut University Hospitals. The study included 60 adult patients with American Society of Anesthesiologists (ASA) grade II-III undergoing elective colorectal surgery with an expected operative duration of at least two hours. Grouping was based upon the intraoperative fluid management Group (R): 6 mL/kg/h. of lactated ringer (LR), Group (C): 12 mL/kg/h. of LR. The preoperative serum Neutrophil gelatinase-associated lipocalin (NGAL) level (basal value) then by the 2nd and 24th postoperative hours, KDIGO (Kidney Disease: Improving Global Outcomes), serum urea and creatinine were documented by the end of 1st and 2nd postoperative days. Intraoperative hypovolemia events were noted as well.
Results: serum NGAL has increased >149 ng/mlin three patients within group C, and two patients within group R; however, the difference was statistically insignificant p= 0.5. KDIGO showed significant difference between the two groups, with higher number of patients in the group R with p= 0.043. Serum urea and creatinine, intraoperative hypovolemic episodes showed insignificant differences between groups.
Conclusion: no evident difference between restrictive and conservative intraoperative fluid strategies was noticed upon the early postoperative serum NGAL and other systems complications in patients undergoing major colorectal surgeries
Ozonated saline intradermal injection: promising therapy for accelerated cutaneous wound healing in diabetic rats
IntroductionThe use of ozonized water is gaining importance in medicine due to its effects on hyperglycemia and wound healing mechanisms.MethodsThis experiment was conducted to assess the impacts of intradermal administration of ozonated water on acute skin wound healing in a diabetic rat model. Sixty-four adult male Wistar rats were randomly divided into two groups: an ozonated water group (O3W) and a control group (CG). Experimental diabetes was chemically induced in the rats by the intraperitoneal administration of 60 mg/kg streptozotocin. One week later, full-thickness skin surgical wounds (1 cm2) were created between the two shoulders of the rats under general anesthesia. The wounds were then daily irrigated with normal saline (CG) or intradermally injected with 1 mL of ozonated water at 10 mg/L O3W. Wound healing was evaluated through macroscopic analysis, measuring wound size, diameter, and percentage of contraction rate before wounding and at 3, 7, 9, 12, 14, 18, 21, 24, and 28 days post-wounding. On days 7, 14, 21, and 28 after induction of the wounds, the body weights and blood glucose levels of rats (8 per group) were measured before the rats were euthanized. Moreover, the morphological structure of the tissue, vascular endothelial and transforming growth factor (VEGF and TGF) affinity and gene expression were examined.ResultsThe O3W group had significantly lower blood glucose levels and wound size and gained body weight. Additionally, epithelial vascularization, stromal edema, TGF, and VEGF gene expression significantly improved in the O3W group.DiscussionTherefore, ozonated water has the potential to enhance and promote cutaneous wound healing in diabetic rats
Validation of a risk prediction model for COVID-19: the PERIL prospective cohort study.
This study aims to perform an external validation of a recently developed prognostic model for early prediction of the risk of progression to severe COVID-19. Patients were recruited at their initial diagnosis at two facilities within Hamad Medical Corporation in Qatar. 356 adults were included for analysis. Predictors for progression of COVID-19 were all measured at disease onset and first contact with the health system. The C statistic was 83% (95% CI: 78%-87%) and the calibration plot showed that the model was well-calibrated. The published prognostic model for the progression of COVID-19 infection showed satisfactory discrimination and calibration and the model is easy to apply in clinical practice.d.This study was approved by the medical ethics committee of Qatar University and Hamad Medical Corporation (protocol nuos. QU-IEB 1434-E/20 and MRC 05-137, respectively) and written informed consent was obtained from all participants