Stages Of Assembly Research Articles

Effect of Clamping Compression on the Mechanical Performance of a Carbon Paper Gas Diffusion Layer in Polymer Electrolyte Membrane Fuel Cells.

During all the assembly stages of a polymer electrolyte membrane fuel cell (PEMFC) stack, gas diffusion layers (GDLs) endure clamping loads in the through-plane direction several times. Under such complicated assembly conditions, GDLs have to deform with the changes in structure, surface roughness, pore size, etc. A comprehensive understanding of the compressive performance of GDLs at different clamping phases is crucial to the assembly process improvement of PEMFCs. Two typical clamping compression was designed and performed to get close to the actual assembly conditions of PEMFCs. The results indicate that the initial clamping compression and the magnitude of the maximum clamping load have great impacts on the segmented compressive properties of GDLs. The nonlinear compressive performance of the GDL is mainly attributed to the unique microstructural information. The rough surface morphology contributes to the initial compressive characteristics where the big strain along with the small stress occurs, and the irreversible failures such as carbon fiber breakages and adhesive failures between fibers and binders account for the hysteresis between different compression stages. Importantly, it is found that the clamping compression hardly influences the small pore distribution below 175 μm but affects the large pore distribution over 200 μm.

Electrochemical DNA biosensor for chronic myelocytic leukemia based on hybrid nanostructure

The present research refers to elaborating a new label-free electrochemical biosensor used to detect the BCR/ABL fusion gene. We used a hybrid nanocomposite composed of chitosan and zinc oxide nanoparticles (Chit-ZnONP) immobilized on a polypyrrole (PPy) film. DNA segments were covalently immobilized, allowing biomolecular recognition. Atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to evaluate the assembly stages of the biosensor. The biosensor’s analytical performance was investigated using recombinant plasmids containing the target oncogene and clinical samples from patients with chronic myeloid leukemia (CML). A limit of detection (LOD) of 1.34 fM, limit of quantification (LOQ) of 4.08 fM, and sensitivity of 34.03 μA fM−1 cm2 were calculated for the BCR/ABL fusion oncogene. The sensing system exhibited high specificity, selectivity, and reproducibility with a standard deviation (SD) of 4.21%. Additionally, a linear response range was observed between 138.80 aM to 13.88 pM with a regression coefficient of 0.96. Also, the biosensor shows easy operationalization and fast analytical response, contributing to the early cancer diagnosis. The proposed nanostructured device is an alternative for the genetic identification BCR/ABL fusion gene.

Design of Portable Nano-hydro Generator for Lighting in Mountain Areas

Electricity needs in mountainous areas have not been optimal, so there need to be alternative power plants to meet the electricity supply in the mountainous area. For this reason, this study made an alternative power plant tool with the title Nano-hydro Generator Design Easy to Carry For Lighting In Mountainous Areas. The creation of this tool has several stages, including the first stage of making graphic design through SketchUp applications, then the second stage of the tool assembly in the form of mechanical design and civilian build, then the third stage of testing tools through water media, and the last stage of data retrieval to see if this tool works optimally. Based on the results of trials and data collection obtained, the average rotation speed of the turbine of 48.6 rpm, the rotation speed of the generator of 194.3 rpm, and a voltage of 6.3 volts.

Trade Continuity and Global Production Sharing in Emerging Economies: Evidence from Panel Gravity Analysis

ABSTRACT This article examines the effect of trade continuity, measured by the lagged imports of intermediate goods, on global production sharing in emerging economies. We estimate an augmented gravity model using the Poisson pseudo maximum likelihood method with a panel dataset of bilateral exports of 29 emerging economies from 2004 to 2017. Our results show that trade continuity positively affects global production sharing. We provide new empirical evidence that trade continuity is process-specific and may vary between parts and components and final assembly stages. Our findings have policy implications on the process-specific nature of global production sharing.

Aplikasi Pembelajaran Percakapan Bahasa Arab dan Inggris Berbasis Android

Nurul Haramain Islamic Boarding School NW Narmada is a private educational institution that applies English and Arabic as daily languages ​​for students in the boarding school environment. However, students who have just entered the Islamic boarding school are given up to six months to learn English and Arabic. Until now, Nurul Haramain Islamic Boarding School NW Narmada in teaching Arabic and English to students still uses the conventional learning process without using the help of learning media. Most of the students did not listen to the teacher delivering the subject matter, difficulties in understanding the material, and the lack of interest of the students in Arabic and English conversations. Therefore, this study aims to develop an application for learning conversational English and Arabic based on Android for class 1 students of Mts Nurul Haramain. The application development stages use the Luther Sutopo model which consists of the Concept, Design, Material Collecting, Assembly, Testing, and Distrubution stages. The application that has been developed was tested on 30 respondents related to application functionality, where the results of application functionality were 78% in the Good category, so that it can help class 1 students of Mts Islamic boarding school Nurul Haramain learn English and Arabic conversation with the correct pronunciation.

The Influence of Assembly Workplace Layout on Ergonomics

Assembly is an important element in the production process. It largely influences the quality of the product and especially the time required to produce the final product. Studies in the field of assembly show that as technology advances, it is necessary to use new improvements at each stage of production, which includes the assembly stage. The aim of every enterprise should be to make the best and most economical use of all the resources at its disposal, on the one hand, and to increase productivity, on the other. Nowadays, ergonomics must be taken into account when solving problems or rationalizing assembly, since most assembly operations are carried out manually. In the theoretical part of the document, the assembly process is described together with the factors that influence it, focusing on manual assembly and its impact on ergonomics. The practical part describes an experiment carried out with the aim to increase the ergonomics of workers and to make the assembly process more efficient at an assembly workplace in a selected industrial enterprise through pre-arrangement of the workplace.

Virtual shimming simulation for smart assembly of aircraft skin panels based on a physics-driven digital twin

A leading challenge in the assembly process of aircraft skin panels is the precise control of part-to-part gaps to avoid excessive pre-tensions of the fastening element which, if exceeded, impair the durability and the response under dynamics loads of the whole skin assembly. The current practice is to measure the gap in specific points of the assembly with parts already at their final location, and then be-spoke shims are machined and inserted between the mating components to fill the gap. This process involves several manual measurement-fit-adjust quality loops, such as loading parts on the assembly frame, measuring gaps, off-loading parts, adding be-spoke shims and re-positioning parts ready for the fastening operation—as a matter of fact, the aircraft is re-assembled at least twice and therefore the current practice has been proved highly cost and time ineffective. Additionally, the gap measurement relies on manual gauges which are inaccurate and unable to follow the actual 3D profile of the gap. Taking advantage of emerging tools such as in-line measurement systems and large-scale physics-based simulations, this paper proposes a novel methodology to predict the part-to-part gap and therefore minimise the need for multiple quality loops. The methodology leverages a physics-driven digital twin model of the skin assembly process, which combines a physical domain (in-line measurements) and a digital domain (physics-based simulation). Central to the methodology is the variation model of the multi-stage assembly process via a physics-based simulation which allows to capture the inherent deformation of the panels and the propagation of variations between consecutive assembly stages. The results were demonstrated during the assembly process of a vertical stabiliser for commercial aircraft, and findings showed a significant time saving of 75% by reducing costly and time-consuming measurement-fit-adjust quality loops.

RNA Post-Transcriptional Modifications in Two Large Subunit Intermediates Populated in E. coli Cells Expressing Helicase Inactive R331A DbpA.

23S ribosomal RNA (rRNA) of Escherichia coli 50S large ribosome subunit contains 26 post-transcriptionally modified nucleosides. Here, we determine the extent of modifications in the 35S and 45S large subunit intermediates, accumulating in cells expressing the helicase inactive DbpA protein, R331A, and the native 50S large subunit. The modifications we characterized are 3-methylpseudouridine, 2-methyladenine, 5-hydroxycytidine, and nine pseudouridines. These modifications were detected using 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate (CMCT) treatment followed by alkaline treatment. In addition, KMnO4 treatment of 23S rRNA was employed to detect 5-hydroxycytidine modification. CMCT and KMnO4 treatments produce chemical changes in modified nucleotides that cause reverse transcriptase misincorporations and deletions, which were detected employing next-generation sequencing. Our results show that the 2-methyladenine modification and seven uridines to pseudouridine isomerizations are present in both the 35S and 45S to similar extents as in the 50S. Hence, the enzymes that perform these modifications, namely, RluA, RluB, RluC, RluE, RluF, and RlmN, have already acted in the intermediates. Two uridines to pseudouridine isomerizations, the 3-methylpseudouridine and 5-hydroxycytidine modifications, are significantly less present in the 35S and 45S, as compared to the 50S. Therefore, the enzymes that incorporate these modifications, RluD, RlmH, and RlhA, are in the process of modifying the 35S and 45S or will incorporate these modifications during the later stages of ribosome assembly. Our study employs a novel high throughput and single nucleotide resolution technique for the detection of 2-methyladenine and two novel high throughput and single nucleotide resolution techniques for the detection of 5-hydroxycytidine.

Frequent Spindle Assembly Errors Require Structural Rearrangement to Complete Meiosis in Zea mays.

The success of an organism is contingent upon its ability to faithfully pass on its genetic material. In the meiosis of many species, the process of chromosome segregation requires that bipolar spindles be formed without the aid of dedicated microtubule organizing centers, such as centrosomes. Here, we describe detailed analyses of acentrosomal spindle assembly and disassembly in time-lapse images, from live meiotic cells of Zea mays. Microtubules organized on the nuclear envelope with a perinuclear ring structure until nuclear envelope breakdown, at which point microtubules began bundling into a bipolar form. However, the process and timing of spindle assembly was highly variable, with frequent assembly errors in both meiosis I and II. Approximately 61% of cells formed incorrect spindle morphologies, with the most prevalent being tripolar spindles. The erroneous spindles were actively rearranged to bipolar through a coalescence of poles before proceeding to anaphase. Spindle disassembly occurred as a two-state process with a slow depolymerization, followed by a quick collapse. The results demonstrate that maize meiosis I and II spindle assembly is remarkably fluid in the early assembly stages, but otherwise proceeds through a predictable series of events.

Niche differentiation drives microbial community assembly and succession in full-scale activated sludge bioreactors

Network models and community phylogenetic analyses are applied to assess the composition, structure, and ecological assembly mechanisms of microbial communities. Here we combine both approaches to investigate the temporal dynamics of network properties in individual samples of two activated sludge systems at different adaptation stages. At initial assembly stages, we observed microbial communities adapting to activated sludge, with an increase in network modularity and co-exclusion proportion, and a decrease in network clustering, here interpreted as a consequence of niche specialization. The selective pressure of deterministic factors at wastewater treatment plants produces this trend and maintains the structure of highly functional and specialized communities responding to seasonal environmental changes.

Modelling the 2D object recognition task in manufacturing context: An information‐based model

In the last decays, manufacturing systems evolved to meet the high product variety required by the market. Different products can be manufactured in the mixed-model assembly lines, with an increase in the process complexity. In these production systems, the required flexibility is mainly provided by operators in the final assembly stages. Here, human errors could lead to high economic losses. A lack is observed in available research concerning a formal quantification of manufacturing complexity considering the joint effect of shape complexity and similarity in the mix variety. This paper focuses on operator decision-making in 2D object recognition tasks, since this is the most critical task performed in mixed model assembly systems. A novel model to quantify the information content in 2D object recognition task is proposed. The model is based on the Shannon's Entropy theory and considers both shape complexity and object similarities. Numerical experiments are provided, and results obtained show the effectiveness of the model in capturing the joint effect of shape complexity and similarities on the task information content. The proposed model can be adopted in a production environment for re-allocating tasks/sub-tasks to avoid the high amount of information to be processed affecting operators' performance.

Concerted modification of nucleotides at functional centers of the ribosome revealed by single-molecule RNA modification profiling.

Nucleotides in RNA and DNA are chemically modified by numerous enzymes that alter their function. Eukaryotic ribosomal RNA (rRNA) is modified at more than 100 locations, particularly at highly conserved and functionally important nucleotides. During ribosome biogenesis, modifications are added at various stages of assembly. The existence of differently modified classes of ribosomes in normal cells is unknown because no method exists to simultaneously evaluate the modification status at all sites within a single rRNA molecule. Using a combination of yeast genetics and nanopore direct RNA sequencing, we developed a reliable method to track the modification status of single rRNA molecules at 37 sites in 18 S rRNA and 73 sites in 25 S rRNA. We use our method to characterize patterns of modification heterogeneity and identify concerted modification of nucleotides found near functional centers of the ribosome. Distinct, undermodified subpopulations of rRNAs accumulate upon loss of Dbp3 or Prp43 RNA helicases, suggesting overlapping roles in ribosome biogenesis. Modification profiles are surprisingly resistant to change in response to many genetic and acute environmental conditions that affect translation, ribosome biogenesis, and pre-mRNA splicing. The ability to capture single-molecule RNA modification profiles provides new insights into the roles of nucleotide modifications in RNA function.

Foreign Investment and Upgrading in the Garment Sector in Africa and Asia

AbstractIn many developing countries, the apparel industry is seen as a ‘stepping stone’ towards industrialisation. Countries rely on foreign investment to enter the garment sector by engaging in simple assembly production and aim to gradually upgrade along the value chain by building their networks and capabilities. By comparing case studies in Africa and Asia, this article shows that foreign investors contribute differently to upgrading and creating linkages. The study reviews the historical experiences of Bangladesh, Cambodia, Lesotho and Madagascar to understand the roles played by various types of foreign investors in contributing to upgrading. The model of production of these investors and their embeddedness in the host countries’ markets shape their contribution towards upgrading. This has important policy implications, suggesting that government policies aiming to develop the garment sector beyond the assembly stage need to correctly identify and attract the investors that are most likely to be or become ‘embedded’. The case studies also highlight the importance of creating a domestic class of entrepreneurs that can actively contribute to the development of the garment industry.

A cooperative memetic algorithm with feedback for the energy-aware distributed flow-shops with flexible assembly scheduling

With economic globalization and increasingly concerned sustainable manufacturing, energy-aware distributed scheduling and flexible assembly are significant to optimize global supply chains. Considering the setup and transportation times, this paper addresses the energy-aware distributed flow-shop with flexible assembly scheduling problem (EADFFASP), which contains four strongly coupled sub-problems at both production and assembly stages, i.e., factory assignment of all jobs and sequence of jobs in each factory as well as assembly machine assignment of all products and sequence of products. To minimize total tardiness and energy consumption simultaneously, a mathematical formulation is presented and a cooperative memetic algorithm with feedback (CMAF) is proposed. First, two problem-specific heuristics are designed to initialize population collaboratively with certain quality and diversity. Second, a cooperative search with a feedback mechanism is proposed via utilizing the history information. Third, a local intensification with multiple problem-specific operators is designed to enhance the exploitation. Fourth, multiple selection strategies are utilized cooperatively to balance the exploration and exploitation. Besides, an energy-saving strategy is employed to further reduce energy consumption. The effect of parameter setting is investigated and extensive numerical comparisons are carried out. The results demonstrate the effectiveness of both the feedback mechanism and local intensification, and the comparisons also show that the CMAF outperforms the existing algorithms in solving the EADFFASP.

MOTION GRAPHIC SEBAGAI MEDIA SOSIALISASI TENTANG PUBLIC RELATION UNTUK KARYAWAN OWNTALK.CO.ID

The development of technology in various aspects is very influential in the field of information and communication. This development can be proven by the existence of motion graphics. One company that implements motion graphics is Owntalk.co.id. Owntalk.co.id is an online news media site that was established on August 19, 2019. As a new company that is 2 years old, currently, Owntalk.co.id needs a public relations division that functions to improve the company's image and build relationships through its employees. This study aims to socialize public relations through the creation of motion graphics that are unique and easy to understand by employees of Owntalk.co.id. The benefit of public relations socialization using motion graphics is the establishment of an understanding of public relations therefore the employees can implement public relations activities according to their roles and functions. This research uses the Luther Sutopo design method, with 6 stages of concept, design, collecting, assembly, testing, and distribution materials. In this study, the results were in the form of a motion graphics video with a duration of 2 minutes 33 seconds with a percentage of 96.8%, which means that this motion graphics video is useful for Owntalk.co.id in disseminating public relations materials to its employees.

Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles

BackgroundWe recently published evidence to suggest that two populations of stem cells including very small embryonic-like stem cells (VSELs) and ovarian stem cells (OSCs) in ovary surface epithelium (OSE) undergo proliferation/differentiation, germ cell nests (GCN) formation, meiosis and eventually differentiate into oocytes that assemble as primordial follicles on regular basis during estrus cycle. Despite presence of stem cells, follicles get exhausted with advancing age in mice and result in senescence equivalent to menopause in women. Stem cells in aged ovaries can differentiate into oocytes upon transplantation into young ovaries, however, it is still not well understood why follicles get depleted with advancing age despite the presence of stem cells. The aim of the present study was to study stem cells and GCN in aged ovaries.MethodsOSE cells from aged mice (> 18 months equivalent to > 55 years old women) were enzymatically separated and used to study stem cells. Viable (7-AAD negative) VSELs in the size range of 2–6 µm with a surface phenotype of Lin−CD45−Sca-1+ were enumerated by flow cytometry. Immuno-fluorescence and RT-PCR analysis were done to study stem/progenitor cells (OCT-4, MVH, SCP3) and transcripts specific for VSELs (Oct-4A, Sox-2, Nanog), primordial germ cells (Stella), germ cells (Oct-4, Mvh), early meiosis (Mlh1, Scp1) and ring canals (Tex14).ResultsPutative VSELs and OSCs were detected as darkly stained, spherical cells with high nucleo-cytoplasmic ratio along with germ cells nests (GCN) in Hematoxylin & Eosin stained OSE cells smears. Germ cells in GCN with distinct cytoplasmic continuity expressed OCT-4, MVH and SCP3. Transcripts specific for stem cells, early meiosis and ring canals were detected by RT-PCR studies.ConclusionRather than resulting as a consequence of accelerated loss of primordial follicle and their subsequent depletion, ovarian senescence/menopause occurs as a result of stem cells dysfunction. VSELs and OSCs exist along with increased numbers of GCNs arrested in pre-meiotic or early meiotic stage in aged ovaries and primordial follicle assembly is blocked possibly due to age-related changes in their microenvironment.

Psb34 protein modulates binding of high-light-inducible proteins to CP47-containing photosystem II assembly intermediates in the cyanobacterium Synechocystis sp. PCC 6803

Assembly of photosystem II (PSII), a water-splitting catalyst in chloroplasts and cyanobacteria, requires numerous auxiliary proteins which promote individual steps of this sequential process and transiently associate with one or more assembly intermediate complexes. In this study, we focussed on the role of a PSII-associated protein encoded by the ssl1498 gene in the cyanobacterium Synechocystis sp. PCC 6803. The N-terminal domain of this protein, which is here called Psb34, is very similar to the N-terminus of HliA/B proteins belonging to a family of high-light-inducible proteins (Hlips). Psb34 was identified in both dimeric and monomeric PSII, as well as in a PSII monomer lacking CP43 and containing Psb28. When FLAG-tagged, the protein is co-purified with these three complexes and with the PSII auxiliary proteins Psb27 and Psb28. However, the preparation also contained the oxygen-evolving enhancers PsbO and PsbV and lacked HliA/B proteins even when isolated from high-light-treated cells. The data suggest that Psb34 competes with HliA/B for the same binding site and that it is one of the components involved in the final conversion of late PSII assembly intermediates into functional PSII complexes, possibly keeping them free of Hlips. Unlike HliA/B, Psb34 does bind to the CP47 assembly module before its incorporation into PSII. Analysis of strains lacking Psb34 indicates that Psb34 mediates the optimal equilibrium of HliA/B binding among individual PSII assembly intermediates containing CP47, allowing Hlip-mediated photoprotection at all stages of PSII assembly.

Prospective collagen IVα345 therapies for Alport syndrome.

In Alport syndrome, over 1,700 genetic variants in the COL4A3, COL4A4, and COL4A5 genes cause the absence or malfunctioning of the collagen IVα345 scaffold - an essential component of the glomerular basement membrane (GBM). Therapies are limited to treatment with Angiotensin-Converting enzyme (ACE) inhibitors to slow progression of the disease. Here, we review recent progress in therapy development to replace the scaffold or restore its function. Multiple approaches emerged recently for development of therapies that target different stages of production and assembly of the collagen IVα345 scaffold in the GBM. These approaches are based on (1) recent advances in technologies allowing to decipher pathogenic mechanisms that underlie scaffold assembly and dysfunction, (2) development of DNA editing tools for gene therapy, (3) RNA splicing interference, and (4) control of mRNA translation. There is a growing confidence that these approaches will ultimately provide cure for Alport patients. The development of therapy will be accelerated by studies that provide a deeper understanding of mechanisms that underlie folding, assembly, and function of the collagen IVα345 scaffold.

РЕШЕНИЕ КОНСТРУКТОРСКО-ТЕХНОЛОГИЧЕСКИХ ЗАДАЧ НА СТАДИИ ПРОЕКТИРОВАНИЯ СПЕЦИФИКАЦИИ ШИНЫ РАДИАЛЬНОЙ КОНСТРУКЦИИ

Methods are considered for solving design and technological problems at the design stage of the radial tire specification. On the basis of the theory of gridshells, a scheme is constructed for calculating the distribution of materials in the radial section of an uncured and vulcanized radial tire. For a flat method of assembling the radial tire, algorithms for calculating profiled parts are proposed. Algorithms are considered for finding the geometry of the shaping surfaces of the tread and sidewall parts. The boundary-value problem of finding the profile of the molded uncured tire at the second stage of assembly has been solved. A method is proposed for determining the parameters of industrial equipment for tire assembly. The experiments carried out to test the accepted hypotheses of the theory of elasticity are described.

Rubredoxin 1 Is Required for Formation of the Functional Photosystem II Core Complex in Arabidopsis thaliana.

Chloroplast thylakoid protein rubredoxin 1 (RBD1) in Chlamydomonas and its cyanobacterial homolog RubA contain a rubredoxin domain. These proteins have been proposed to participate in the assembly of photosystem II (PSII) at early stages. However, the effects of inactivation of RBD1 on PSII assembly in higher plants are largely unclear. Here, we characterized an Arabidopsis rbd1 mutant in detail. A drastic reduction of intact PSII complex but relatively higher levels of assembly intermediates including PSII RC, pre-CP47, and pre-CP43 were found in rbd1. Polysome association and ribosome profiling revealed that ribosome recruitment of psbA mRNA is specifically reduced. Consistently, in vivo protein pulse-chase labeling showed that the rate of D1/pD1 synthesis is significantly reduced in rbd1 compared with WT. Moreover, newly synthesized mature D1 and pD1/D2 can assemble into the PSII reaction center (RC) complex but further formation of larger PSII complexes is nearly totally blocked in rbd1. Our data imply that RBD1 is not only required for the formation of a functional PSII core complex during the early stages of PSII assembly but may also be involved in the translation of D1 in higher plants.