A process chain for integrating microfluidic interconnection elements by micro- overmoulding of thermoplastic elastomers

This paper presents a process chain for in-line integration of microfluidic interconnection elements by a variant of micro-injection moulding (mu IM). A SEBS-based thermoplastic elastomer (TPE) was moulded over polymethylmethacrylate (PMMA) to produce a hybrid microfluidic structure with an aspect ratio of 2. The process chain implemented micro-milling for fabricating micro-structured tool inserts, and mu IM and micro-overmoulding was used for replication. A two-plate mould was used for moulding the substrate, whilst a three-plate mould with a replaceable insert was used for TPE overmoulding. The presented application was an interconnect system for a microfluidic device, which enabled direct fitting of standard tubes into microfluidic substrates. A leakage test showed that the interconnection was leak-proof within a range of flow rates between 0.32 and 0.62 ml min(-1)

The role of early learning experience in shaping teacher cognition and technology use

This chapter explores the role of teachers' early learning experiences in shaping their pedagogical beliefs and practice specifically in relation to technology use. Following a case study approach, the accounts of three in-service Arabic language teachers from a private institution of higher education in Cairo, Egypt, were examined. Practitioners with years of professional experience are not expected to have encountered elements of technology as we know today in their schooling. Nevertheless, findings suggest that conceptions formed early in life of what constitutes “good” or “bad” teaching act as filters through which new experiences, including the use of digital media, are internalized. As imprints of early learning experiences are manifested in teaching, it is the responsibility of teachers to look back on them for possible influences on their pedagogical theories. In complementary fashion, the study foregrounds the role of teacher education in mediating initial conceptualizations of teaching and learning and accentuates the value of reflective practice for continuing teacher development

Creating movable interfaces by micro-powder injection moulding

This paper presents a novel in situ technique to produce articulated components with high-precision, micro-scale movable interfaces by micro-powder injection moulding (μPIM). The presented process route is based on the use of micro-scale sacrificial layer between the movable subcomponents which is eliminated during the debinding step, creating a dimensionally-controlled, micro-scale mobile interface. The fabrication technique combines the advantages of micro-powder overmoulding, catalytic debinding and sintering. The demonstrated example was a finger bone prosthesis joint consisting of two sub-components with an interface between components of 200 μm in size. The geometries of the sub-components were designed such that they are inseparable throughout the process whilst allowing them to move relative to each other after the debinding stage. The components produced showed the feasibility of the process route to produce readily-assembled meso-, and potentially micro-, scale articulated system

Effect of Nitrogen, Phosphorus, Potassium and Cutting on the Regrowth and Insect Infestation of a Sorghum and Berseem Clover in Egypt

The objective of this study was to determine the minimum quantities of phosphorus and potassium which must be applied with varying amounts of nitrogen in order to maintain maximum hay production and minimum level of insect infestation. This was more pronounced at the higher N rates and caused a significant N x K interaction during each of these years. There was no yield response to applied phosphorus at any N rate. Relation between levels of nitrogen and infestation percentage was positive but infestation rate decreased with the increase of potassium levels while there was no relation between levels of phosphorus fertilization and infestation percentage

Recent Research Trends in Arabic-Oriented Radio and TV Channels: An Analytical Review

The current study investigated the most significant scientific research conducted in this field in both Arabic and English to provide an integrated view of contemporary research trends in Arabic radio/channels and to identify the findings of prior studies. In Arabic, between 2013 to 2021, the researcher conducted a second-level qualitative analysis process on several research papers and studies, totaling 88 research papers.Compared to oriented channels, the analysis of radio-targeted discourse has been the subject of a relatively small number of studies, and even in the most recent studies, the radio-targeted discourse has been regarded as a historical narrative. Youth represented the most significant percentage of the target audience for research-oriented radios and channels, followed by adolescents. Despite an increase in the Arab school's contributions to the research of oriented radios and channels and its desire to identify the image of Arab countries' issues and crises in Western media, no studies were conducted. Future studies should focus on examining how to present a correct media image or correct the false image that has been presented

A Study of the Turbulent Flows in Sloping and Adversely Sloping Rectangular Culverts

In this paper, an experimental investigation was carried out to study the turbulent flows and flow characteristics through sloping and adversely sloping rectangular culverts in a rectangular channel of constant width using Laser Doppler Velocimetry (LDV). Also, experimental study was carried out to investigate the characteristics of the hydraulic jump occurring in a sloping and adversely sloping rectangular culvert with pressurized flow downstream from the jump and a submerged culvert outlet. Experiments were conducted on a culvert with relatively small slopes to study the variation of the relative tailwater depth with the main parameters affecting the jump in sloping and adversely sloping culverts. These parameters include the channel bottom slope, the initial Froude number and the ratio of the initial depth to culvert height. To study the turbulence characteristics, precise and accurate measurements of the mean fluctuating flow quantities such as streamwise and vertical mean velocity components, and streamwise and vertical turbulence intensity components and turbulence shear stress were carried out. Also, this paper presents the results of a Laser Doppler Velocimetry study of hydraulic jumps in a culvert with different relative tailwater depths and different initial Froude numbers. The characteristics of hydraulic jumps were discussed and analyzed. Non– dimensional design curves were provided to relate the jump characteristics. The maximum vertical velocity in the recirculating zone for all jumps is about 6% of the initial velocity. The results show that the maximum streamwise velocity near the center plane was smaller than that near the side wall. The turbulence shear stress near the center was about (35-45)% higher than that near the side wall. After the jump, the flow will recover into a two-dimensional flow

Alterations in hepatic miRNA expression during negative energy balance in postpartum dairy cattle

peer-reviewedBackground Negative energy balance (NEB), an altered metabolic state, occurs in early postpartum dairy cattle when energy demands to support lactation exceed energy intake. During NEB the liver undergoes oxidative stress and increased breakdown of fatty acids accompanied by changes in gene expression. It is now known that micro RNAs (miRNA) can have a role in mediating such alterations in gene expression through repression or degradation of target mRNAs. miRNA expression is known to be altered by metabolism and environmental factors and miRNAs are implicated in expression modulation of metabolism related genes. Results miRNA expression was profiled in the liver of moderate yielding dairy cattle under severe NEB (SNEB) and mild NEB (MNEB) using the Affymetrix Gene Chip miRNA_2.0 array with 679 probe sets for Bos-taurus miRNAs. Ten miRNAs were found to be differentially expressed using the ‘samr’ statistical package (delta = 0.6) at a q-value FDR of < 12%. Five miRNAs including miR-17-5p, miR-31, miR-140, miR-1281 and miR-2885 were validated using RT-qPCR, to be up-regulated under SNEB. Liver diseases associated with these miRNAs include non-alcoholic fatty liver (NAFLD) and hepatocellular carcinoma (HCC). miR-140 and miR-17-5p are known to show differential expression under oxidative stress. A total of 32 down-regulated putative target genes were also identified among 418 differentially expressed hepatic genes previously reported for the same animal model. Among these, GPR37 (G protein-coupled receptor 37), HEYL (hairy/enhancer-of-split related with YRPW motif-like), DNJA1, CD14 (Cluster of differentiation 14) and GNS (glucosamine (N-acetyl)-6-sulfatase) are known to be associated with hepatic metabolic disorders. In addition miR-140 and miR-2885 have binding sites on the most down-regulated of these genes, FADS2 (Fatty acid desaturase 2) which encodes an enzyme critical in lipid biosynthesis. Furthermore, HNF3-gamma (Hepatocyte nuclear factor 3-gamma), a hepatic transcription factor (TF) that is involved in IGF-1 expression regulation and maintenance of glucose homeostasis is a putative target of miR-31. Conclusions This study shows that SNEB affects liver miRNA expression and these miRNAs have putative targets in hepatic genes down-regulated under this condition. This study highlights the potential role of miRNAs in transcription regulation of hepatic gene expression during SNEB in dairy cattle. Background Negative energy balance (NEB), an altered metabolic state, occurs in early postpartum dairy cattle when energy demands to support lactation exceed energy intake. During NEB the liver undergoes oxidative stress and increased breakdown of fatty acids accompanied by changes in gene expression. It is now known that micro RNAs (miRNA) can have a role in mediating such alterations in gene expression through repression or degradation of target mRNAs. miRNA expression is known to be altered by metabolism and environmental factors and miRNAs are implicated in expression modulation of metabolism related genes. Results miRNA expression was profiled in the liver of moderate yielding dairy cattle under severe NEB (SNEB) and mild NEB (MNEB) using the Affymetrix Gene Chip miRNA_2.0 array with 679 probe sets for Bos-taurus miRNAs. Ten miRNAs were found to be differentially expressed using the ‘samr’ statistical package (delta = 0.6) at a q-value FDR of < 12%. Five miRNAs including miR-17-5p, miR-31, miR-140, miR-1281 and miR-2885 were validated using RT-qPCR, to be up-regulated under SNEB. Liver diseases associated with these miRNAs include non-alcoholic fatty liver (NAFLD) and hepatocellular carcinoma (HCC). miR-140 and miR-17-5p are known to show differential expression under oxidative stress. A total of 32 down-regulated putative target genes were also identified among 418 differentially expressed hepatic genes previously reported for the same animal model. Among these, GPR37 (G protein-coupled receptor 37), HEYL (hairy/enhancer-of-split related with YRPW motif-like), DNJA1, CD14 (Cluster of differentiation 14) and GNS (glucosamine (N-acetyl)-6-sulfatase) are known to be associated with hepatic metabolic disorders. In addition miR-140 and miR-2885 have binding sites on the most down-regulated of these genes, FADS2 (Fatty acid desaturase 2) which encodes an enzyme critical in lipid biosynthesis. Furthermore, HNF3-gamma (Hepatocyte nuclear factor 3-gamma), a hepatic transcription factor (TF) that is involved in IGF-1 expression regulation and maintenance of glucose homeostasis is a putative target of miR-31. Conclusions This study shows that SNEB affects liver miRNA expression and these miRNAs have putative targets in hepatic genes down-regulated under this condition. This study highlights the potential role of miRNAs in transcription regulation of hepatic gene expression during SNEB in dairy cattle

Flatness optimization of micro-injection moulded parts: The case of a PMMA microfluidic component

Micro-injection moulding (µ-IM) has attracted a lot of interest because of its potential for the production of low-cost, miniaturized parts in high-volume. Applications of this technology are, amongst others, microfluidic components for lab-on-a-chip devices and micro-optical components. In both cases, the control of the part flatness is a key aspect to maintaining the component's functionality. The objective of this work is to determine the factors affecting the flatness of a polymer part manufactured by µ-IM and to control the manufacturing process with the aim of minimizing the in-process part deformation. As a case study, a PMMA microfluidic substrate with overall dimensions of 10 mm diameter and 1 mm thickness was investigated by designing a µ-IM experiment having flatness as the experimental response. The part flatness was measured using a micro-coordinate measuring machine. Finite elements analysis was also carried out to study the optimal ejection pin configuration. The results of this work show that the control of the µ-IM process conditions can improve the flatness of the polymer part up to about 15 µm. Part flatness as low as 4 µm can be achieved by modifying the design of the ejection system according to suggested guideline