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81.
KS Makarova IuI Vul'f IA Seledtsov VA Ratner 《Canadian Metallurgical Quarterly》1995,31(12):1614-1629
Transposons of gypsy group are assigned to LTR-containing retrotransposons present in the genomes of invertebrates, fungi, and plants. In this work, a theoretical analysis of the potential products of ORFs of these retrotranposons was conducted. Alignments were obtained and trees of similarity were constructed for domains of the POL region. On the basis of the obtained data, two hypothetically monophyletic subgroups of transposons were distinguished within the framework of the gypsy group, settling the genomes of taxonomically related organisms (the subgroup of "true" gypsy of insects and the subgroup of gypsy-like transposons of plants and fungi). A number of peculiarities of the topology of these trees hypothetically indicate cases of genetic conversion and recombination of domains accompanying the evolution of this group. The amino acid substitution fixation rate was evaluated on the basis of comparison of sequences of the protein products of ORFs. Estimates of the time of divergence of subgroups of gypsy-group transposons are significantly less than estimates of the times of divergence of their host species. One explanation for this discrepancy might be the hypothesis of settlement by transposons of the genomes of isolated host species. 相似文献
82.
Hengfei Gu Fei Zhang Shinjae Hwang Anders B. Laursen Xin Liu So Yeon Park Mengjin Yang Rosemary C. Bramante Hussein Hijazi Leila Kasaei Leonard C. Feldman Yao-Wen Yeh Philip E. Batson Bryon W. Larson Mengjun Li Yifei Li Keenan Wyatt James L. Young Krishani Teeluck Kai Zhu Eric Garfunkel G. Charles Dismukes 《Advanced functional materials》2023,33(25):2301196
The rapidly increasing solar conversion efficiency (PCE) of hybrid organic–inorganic perovskite (HOIP) thin-film semiconductors has triggered interest in their use for direct solar-driven water splitting to produce hydrogen. However, application of these low-cost, electronic-structure-tunable HOIP tandem photoabsorbers has been hindered by the instability of the photovoltaic-catalyst-electrolyte (PV+E) interfaces. Here, photolytic water splitting is demonstrated using an integrated configuration consisting of an HOIP/n+silicon single junction photoabsorber and a platinum (Pt) thin film catalyst. An extended electrochemical (EC) lifetime in alkaline media is achieved using titanium nitride on both sides of the Si support to eliminate formation of insulating silicon oxide, and as an effective diffusion barrier to allow high-temperature annealing of the catalyst/TiO2-protected-n+silicon interface necessary to retard electrolytic corrosion. Halide composition is examined in the (FA1-xCsx)PbI3 system with a bandgap suitable for tandem operation. A fill factor of 72.5% is achieved using a Spiro-OMeTAD-hole-transport-layer (HTL)-based HOIP/n+Si solar cell, and a high photocurrent density of −15.9 mA cm−2 (at 0 V vs reversible hydrogen electrode) is attained for the HOIP/n+Si/Pt photocathode in 1 m NaOH under simulated 1-sun illumination. While this thin-film design creates stable interfaces, the intrinsic photo- and electro-degradation of the HOIP photoabsorber remains the main obstacle for future HOIP/Si tandem PEC devices. 相似文献
83.
Leonard Staphorst Mike Holland Leon Pretorius Marthinus Willem Pretorius 《Engineering Management Journal; EMJ》2017,29(1):26-44
Strengthening intellectual property rights for publicly financed research and development (R&D) ensures that research organizations maximize the full national value of the intellectual property that they generate, but potential negative spillover effects on the perceived value of a research alliance might deter an existing alliance partner from continued collaboration or a potential alliance partner from future collaboration. This study, performed in 2010 within the context of the Council for Scientific and Industrial Research in South Africa, aimed to develop a structural equation modeling-based value-mediation governance decision-making model that will enable engineering managers at publicly financed R&D organizations to select optimal governance modes for the research alliances they are establishing to grow their organizations’ R&D capabilities. 相似文献
84.
Avishek Sarbajna Andres Georg Rösch Leonard Franke Uli Lemmer Md Mofasser Mallick 《Advanced Engineering Materials》2023,25(2):2200980
One of the simplest ways to generate electric power from waste heat is thermoelectric (TE) energy conversion. So far, most of the research on thermoelectrics has focused on inorganic bulk TE materials and their device applications. However, high production costs per power output and limited shape conformity hinder applications of state-of-the-art thermoelectric devices (TEDs). In recent years, printed thermoelectrics has emerged as an exciting pathway for their potential in the production of low-cost shape-conformable TEDs. Although several inorganic bulk TE materials with high performance are successfully developed, achieving high performance in inorganic-based printed TE materials is still a challenge. Nevertheless, significant progress has been made in printed thermoelectrics in recent years. In this review article, it is started with an introduction signifying the importance of printed thermoelectrics followed by a discussion of theoretical concepts of thermoelectricity, from fundamental transport phenomena to device efficiency. Afterward, the general process of inorganic TE ink formulation is summarized, and the current development of the inorganic and hybrid inks with the mention of their TE properties and their influencing factors is elaborated. In the end, TEDs with different architecture and geometries are highlighted by documenting their performance and fabrication techniques. 相似文献
85.
Christoph Weigel Valeriya Cherkasova Mathias Holz Hai Binh Phi Christian Görner Tenorio Björn Wilbertz Leonard Voßgrag Thomas Fröhlich Steffen Strehle 《Advanced Engineering Materials》2023,25(9):2201873
Ultralow expansion (ULE) glasses are of special interest for temperature stabilized systems for example in precision metrology. Nowadays, ULE materials are mainly used in macroscopic and less in micromechanical systems. Reasons for this are a lack of technologies for parallel fabricating high-quality released microstructures with a high accuracy. As a result, there is a high demand in transferring these materials into miniaturized application examples, realistic system modeling, and the investigation of microscopic material properties. Herein, a technological base for fabricating released micromechanical structures and systems with a structure height above 100 μm in ULE 7972 glass is established. Herein, the main fabrication parameters that are important for the system design and contribute thus to the introduction of titanium silicate as material for glass-based micromechanical systems are discussed. To study the mechanical properties in combination with respective simulation models, microcantilevers are used as basic mechanical elements to evaluate technological parameters and other impact factors. The implemented models allow to predict the micromechanical system properties with a deviation of only ±5% and can thus effectively support the micromechanical system design in an early stage of development. 相似文献
86.
S Migliaccio S Bernardini WC Wetsel KS Korach T Faraggiana A Teti 《Canadian Metallurgical Quarterly》1998,63(5-6):352-354
Ventriculo-peritoneal shunts (VPS) are the most frequent operative procedures used to treat hydrocephalic children. Abdominal complications of VPS are now a rare event; however, their frequency varies from 5% to 47% according to reports. Anything that causes an obstruction or impediment of the VP derivation system will lead to intracranial hypertension, which requires immediate surgery. From 1985 to 1995 at the Division of Pediatric Surgery of the Federico II University of Naples, ten laparoscopies were performed in ten children with VPS complications. Cerebrospinal fluid pseudocysts were found in four infants. There was one case of abdominal wall perforation by the tip of the catheter at the umbilical level, two bowel obstructions, and one catheter was lost in the abdominal cavity. Finally, two children had malfunctioning of the peritoneal limb of the catheter. The laparoscopic technique was curative in all ten cases, thus avoiding a conventional laparotomy and the consequent risk of adhesions, which could cause further complications. 相似文献
87.
PS Estes J Roos A van der Bliek RB Kelly KS Krishnan M Ramaswami 《Canadian Metallurgical Quarterly》1996,16(17):5443-5456
Presynaptic terminals contain several specialized compartments, which have been described by electron microscopy. We show in an identified Drosophila neuromuscular synapse that several of these compartments-synaptic vesicle clusters, presynaptic plasma membrane, presynaptic cytosol, and axonal cytoskeleton-labeled by specific reagents may be resolved from one another by laser scanning confocal microscopy. Using a panel of compartment-specific markers and Drosophila shibire(ts1) mutants to trap an intermediate stage in synaptic vesicle recycling, we have examined the localization and redistribution of dynamin within single synaptic varicosities at the larval neuromuscular junction. Our results suggest that dynamin is not a freely diffusible molecule in resting nerve terminals; rather, it appears localized to synaptic sites by association with yet uncharacterized presynaptic components. In shi(ts1) nerve terminals depleted of synaptic vesicles, dynamin is quantitatively redistributed to the plasma membrane. It is not, however, distributed uniformly over presynaptic plasmalemma; instead, fluorescence images show "hot spots" of dynamin on the plasma membrane of vesicle-depleted nerve terminals. We suggest that these dynamin-rich domains may mark the active zones for synaptic vesicle endocytosis first described at the frog neuromuscular junction. 相似文献
88.
The goal of stress incontinence surgery is to prevent opening of the urethra during increases in intra-abdominal pressure. Greater refinements in the understanding of the pathophysiology of incontinence and experience with newer treatments have extended surgical thinking beyond the familiar paradigm "to place the urethra in a high retropubic position." When incontinence is associated with vaginal hypermobility, vaginal support may be sufficient to restore continence if the suburethral vaginal wall is sufficiently strong, an evaluation which must often be made by physical examination alone. However, when the vaginal wall is weak, the urethra will require an alternative form of support, usually a sling. If the urethra is intrinsically deficient, vaginal support may not be sufficient to prevent opening during increased intra-abdominal pressure, and coaptation by sling obstruction or periurethral bulking injection may be required. Most laparoscopic approaches to stress incontinence use Burch's method, which offers excellent urethral stability provided the suburethral vaginal wall is strong. Newer insights into the relation between vaginal mobility and urethral closure are discussed, as well as anatomic aspects of the Burch suspension relevant to laparoscopic repair. 相似文献
89.
90.
Leonard Rusli Anthony Luscher Carolyn Sommerich 《International Journal of Industrial Ergonomics》2010,40(6):618-628
The purpose of this study was to investigate the tactile feedback of snap-fit fasteners when used in manual assembly. An important aspect of this assembly process is the assembler’s ability to perceive the snap-fit’s engagement. This sensing of engagement yields a high level of confidence that assembly is both complete and secure. Force and tactile feedback are critical elements in this process. Many snap-fits are used in conjunction with sealing elements that produce a constant force that remains in effect after snap-fit assembly is completed. The effect of sealing element preload magnitude and stiffness was studied using a test station, force deflection measurements, and jury pool data. A low value of preload with low stiffness was determined to be most favorable in terms of force and tactile feedback, with no preload only slightly less favorable. In order to sense the engagement signal of the catch, some resistance to assembly was found to be beneficial. A dimensionless term called “engagement signal-to-hold-force ratio” is proposed as an additional way of rating the effect of assembly forces for snap-fits. It was found that higher signal-to-hold-force ratio, as well as higher values of engagement signal, corresponded to higher confidence of assembly among experimental subjects.