2,391 research outputs found
Evaluation of human umbilical cord blood as a source of embryonic stem cells
Human umbilical cord blood (HUCB) has been poorly characterised as a source of embryonic stem cells (ESCs). The aim of this study, therefore, was to evaluate HUCB as source of mesenchymal stem cells (MSCs) with embryonic characteristics. HUCB was collected from consenting women undergoing elective caesarean sections. HUCB was meticulously explanted into MesenCult media and incubated. Qualitative and quantitative immunophenotyping of cells was achieved using fluorescein isothiocyanate (FITC) labelled antibodies (CD34, CD45, CD29, CD44, CD73 and CD105) phenotypic markers. Immunocytochemistry was carried out for the human ESC markers CD9, stage-specific embryonic antigen-1 and 4 (SSEA-1 and SSEA-4), E-cadherin, Podocalyxin (PODXL), sex-determining region Y-box 2 (SOX2), NANOG and Octamer (OCT3/4). MSCs were cultured to induce differentiation into adipogenic, osteogenic, chondrogenic and neurogenic cells. Immunocytochemistry was used to identify fatty acid binding protein-4 (FABP-4), osteocalcin, aggrecan, SOX2 and oligodendrocyte-4 (Olig-4) markers. The cells were strongly positive for the MSC markers CD29, CD44, CD73 and CD105; these cells also expressed the ESC markers CD9, SSEA-1 and SSEA-4, E-cadherin, PODXL, SOX2, NANOG and OCT3/4. Additionally, the MSCs expressed the adipogenic FABP-4, osteogenic osteocalcin, chondrogenic aggrecan and neural Olig-4 and SOX2 markers after differentiation. Therefore, HUCB is a rich source for MSCs with embryonic characteristics
Nd:YAG laser welding of stainless steel 304 for photonics device packaging
Although pulsed Nd:YAG laser welding has been widely used in microelectronics and photonics packaging industry, a full understanding of various phenomena involved is still a matter of trials and speculations. In this research, an ultra compact pulsed Nd:YAG laser with wavelength of 1.064 µm has been used to produce a spot weld on stainless steel 304. The principal objective of this research is to examine the effects of laser welding parameters such as laser beam peak powers, pulse durations, incident angles, focus point positions and number of shots on the weld dimensions: penetration depth and bead width. The ratio of the penetration depth to the bead width is considered as one of the most critical parameters to determine the weld quality. It is found that the penetration depth and bead width increase when the laser beam peak power, pulse duration and number of shot increase. In contrast, the penetration depth decreases when the laser beam defocus position and incident angle increase. This is due to the reduction of the laser beam intensity causing by the widening of the laser spot size. These experimental results provide a reference on an optimal laser welding operations for a reliable photonics device packaging. The results obtained shows that stainless steel 304 is suitable to be used as a base material for photonics device packaging employing Nd:YAG laser welding technique
Estimation of Some Genetic Parameters, Correlation and Heritability in Various Maize Traits
The study was carried out using ten maize hybrids in spring 2015 and 2016 were planted at the field of Agriculture College, University of Duhok. All treatments arranged in Randomized Complete Block Design (RCBD) with three replications to determine the heritability, genetic advance, correlation and genetic parameters govering the inheritance of grain yield and related agronomic traits. The result showed significant difference among hybrids for studied traits in spring 2015 and 2016 and also the results revealed that hybrids and seasons interaction had a significant difference for all traits. The season’s spring 2015 was superior than spring 2016 in leaf area, days to 75% tasseling and silking, yield and its components. The hybrid (OH40 xIK8) was superior in No. of rows ear-1, No. of kernels row-1,300 kernel weight and kernel yield plant1. All studied traits recorded higher value of heritability, high genetic advance coupled with heritability was observed in leaf area and kernel yield plant-1, thus selection based on these traits will be effective in maize breeding program. Grain yield was positively correlated with leaf area and 300 kernel weight, also No. of row ear-1 exhibited positive correlation coefficient with leaf area, 300-kernell weight and kernel yield plant-1
Current Clinical Practices in Pakistan and Hospital Pharmacist’s Perception towards Their Role: A Qualitative Approach
The professional role of the pharmacist in hospital setting is changing from a focus on preparation of medication to patient oriented approach and now pharmacist assists the patient to get best possible results from medication. The aim of this study was to evaluate the perception of hospital pharmacists towards their role in the healthcare system of Pakistan. A qualitative study design was adopted. Face to face interviews were conducted using a semi structure interview guide. A total of nineteen interviews were conducted and become the part of the study. All the interviews were transcribed verbatim and thematically analyzed for its content. Thematic content analysis yielded five major themes: 1) perception regarding pharmacist-patient interaction, 2) perception towards reducing prescription errors, 3) perception towards pharmacy curriculum, 4) perception towards pharmacist engagement in hospital policies, and 5) perception regarding clinical role of pharmacists.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Comparative Study of Sensorless Control Methods of PMSM Drives
Recently, permanent magnet synchronous motors (PMSMs) are increasingly used in high performance variable speed drives of many industrial applications. This is because the PMSM has many features, like high efficiency, compactness, high torque to inertia ratio, rapid dynamic response, simple modeling and control, and maintenance-free operation. In most applications, the presence of such a position sensor presents several disadvantages, such as reduced reliability, susceptibility to noise, additional cost and weight and increased complexity of the drive system. For these reasons, the development of alternative indirect methods for speed and position control becomes an important research topic. Many advantages of sensorless control such as reduced hardware complexity, low cost, reduced size, cable elimination, increased noise immunity, increased reliability and decreased maintenance. The key problem in sensorless vector control of ac drives is the accurate dynamic estimation of the stator flux vector over a wide speed range using only terminal variables (currents and voltages). The difficulty comprises state estimation at very low speeds where the fundamental excitation is low and the observer performance tends to be poor. The reasons are the observer sensitivity to model parameter variations, unmodeled nonlinearities and disturbances, limited accuracy of acquisition signals, drifts, and dc offsets. Poor speed estimation at low speed is attributed to data acquisition errors, voltage distortion due the PWM inverter and stator resistance drop which degrading the performance of sensorless drive. Moreover, the noises of system and measurements are considered other main problems. This paper presents a comprehensive study of the different methods of speed and position estimations for sensorless PMSM drives. A deep insight of the advantages and disadvantages of each method is investigated. Furthermore, the difficulties faced sensorless PMSM drives at low speeds as well as the reasons are highly demonstrated. Keywords: permanent magnet, synchronous motor, sensorless control, speed estimation, position estimation, parameter adaptation
Notes on the Nesting Biology of the Small Carpenter Bee Ceratina smaragdula (Hymenoptera: Apidae) in Northwestern Pakistan
The nesting biology and some foraging activities of the familiar, brilliant metallic green, small carpenter bee Ceratina (Pithitis) smaragdula (F.) (Hymenoptera: Apidae) is documented from the northwestern-most extent of its natural distribution, as the species is a potentially important pollinator of leguminous and cucurbit crops in the region. Numerous nests around the village of Ismaila, Swabi, Khyber Pakhtunkhwa Province, Pakistan, were observed and sampled from Jun through Aug 2012. Nest details were recorded and foraging times on various floral species were documented, with bees preferentially nesting in wooden stalks of Ravenna grass (Saccharum ravennae L.; Poales: Poaceae), life cycles lasting 28 to 32 d, and conditions offering the potential for easy management. The importance of such studies on wild bees in Pakistan is stressed, as are the development of biotic surveys on bees and the training of regional melittologists, coupled with outreach activities.
Resumen
La biología de la anidación y algunas actividades de forrajeo de la pequeña abeja carpintera Ceratina (Pithitis) smaragdula (F.) (Hymenoptera: Apidae) de tipo familiar y brillante color verde metálico está documentado desde el punto mas noroeste de su distribución natural, ya que la especie es potencialmente un importante polinizador de legumbres y cucurbitáceas en la región. Se observaron numerosos nidos alrededor del pueblo de Ismaila, Swabi, Khyber Pakhtunkhwa Provincia, Pakistán, y se tomaron muestras desde junio hasta agosto del 2012. Los detalles de la anidación fueron registrados y se documentaron los tiempos de forrajeo sobre diversas especies florales, con las abejas preferentemente anidando en los tallos de madera de pasto de Rávena (Saccharum ravennae L.; Poales: Poaceae), los ciclos de vida duran de 28 a 32 dias, y las condiciones que ofrecen el potencial para un fácil manejo. Se destaca la importancia de este tipo de estudio sobre las abejas silvestres en Pakistán, igual que el desarrollo de sondeos bióticos sobre las abejas y la formación de melitólogos regionales, junto con actividades de extensión
Some Chemical Aspects of Tetrahydro-1-thiopyran-4-one Derivatives
3,5-Diarylmethylene-2,6-diphenyltetrahydrothiopyran-4-thiones,
2, reacted with two or four moles of bromine to form 3-aryimethylene
5-bromoarylmethylene- 2,6-dipheny1tetrahydrothiopyran-
-4-thione, 3, and 3-arylmethylene-5-bromoarylmethylene-2,6-dibromo- 2,6-diphenyltetrahydrothiopyran-4-thione, 5, respectively. Compound 2a reacted with amines giving 2,6-diphenyl-5-iminophenylmethyl- 3-phenylmethylenetetrahydrothiopyran-4-thiones, 6. Diphenydiazomethane and 9-diazofluorene converted 2a into 4-diphenylethylene- 2,6-dipheny1-3,5 diphenylmethylenetetrahydrothiopyran, 7, and 2,6-diphenyl-3,5-diphenylmethylene-4-(9-fluorenylidene) tetrahydrothiopyran,
8, respectively. Compounds 2 with copper-bronze afforded 3,3\u27,5,5\u27-tetraarylmethylene-2,2\u27 ,6,6\u27-tetraphenyl-Lr-thio- 4,4\u27 dipyranylidenes
Characterisation of the potentially diverse transcriptional regulatory mechanisms of human coagulation PZ gene.
Protein Z (PZ) is a vitamin k-dependent plasma glycoprotein produced mainly in the liver, which circulates as a complex with PZ-dependent protease inhibitor. Human PZ has been reported as having both procoagulant and anticoagulant activity, but its anticoagulant role appears to be more physiologically relevant. PZ levels vary widely among healthy individuals (normal range of 0.6 to 5.7 mug/mL) with the average being higher in men than women. The aim of this study was to investigate the mechanisms by which PZ expression is controlled at the level of transcription, including whether hormonal and/or inflammatory signals modify expression and, therefore, possibly account, at least in part, for the wide normal range.Bioinformatic analysis enabled the identification of two age stable elements (ASEs) in the PZ gene promoter showing close homology to those found in two evolutionarily related proteins, human factor IX and protein C. These regions were found to be bound specifically by potentially the same or a similar protein; but the identity of the protein could not be confirmed as either PEA3 or Ets1, although transactivation data from HepG2 cells suggested PEA3 is important in controlling expression of endogenous PZ.Two further regions, proximal and distal to the PZ transcription start site, were identified by bioinformatic analysis for binding of hepatocyte nuclear factor 4 alpha (HNF4alpha), with the proximal site also reported by Sugawara and colleagues. Although both sites showed specific binding of protein only the protein binding the proximal site was confirmed as being HNF4alpha. The importance of HNF4alpha was further demonstrated by overexpression and siRNA knockdown producing a respective increase and decrease in PZ mRNA levels. Furthermore, the role of steroid hormones and inflammatory signals as potential modifiers of PZ transcription were also assessed in the HepG2 model system. This study has demonstrated, to varying degrees, the importance of tissue-specific factors (HNF4alpha), more ubiquitous factors (PEA3, Ets1), steroid hormones (oestrogen and glucocorticoid) and inflammatory pathways (bacterial LPS induction) on the regulation of PZ gene transcription
An Improved Fuzzy Logic Controller Design for PV Inverters Utilizing Differential Search Optimization
This paper presents an adaptive fuzzy logic controller (FLC) design technique for photovoltaic (PV) inverters using differential search algorithm (DSA). This technique avoids the exhaustive traditional trial and error procedure in obtaining membership functions (MFs) used in conventional FLCs. This technique is implemented during the inverter design phase by generating adaptive MFs based on the evaluation results of the objective function formulated by the DSA. In this work, the mean square error (MSE) of the inverter output voltage is used as an objective function. The DSA optimizes the MFs such that the inverter provides the lowest MSE for output voltage and improves the performance of the PV inverter output in terms of amplitude and frequency. The design procedure and accuracy of the optimum FLC are illustrated and investigated using simulations conducted for a 3 kW three-phase inverter in a MATLAB/Simulink environment. Results show that the proposed controller can successfully obtain the desired output when different linear and nonlinear loads are connected to the system. Furthermore, the inverter has reasonably low steady state error and fast response to reference variation
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