Mechanisms of ventilation in lower vertebrates: adaptations to respiratory and nonrespiratory constraints

1989 ◽  
Vol 67 (12) ◽  
pp. 2943-2955 ◽  
Author(s):  
William K. Milsom
Keyword(s):  
Thin Body ◽  
Low Oxygen ◽  
Adequate Ventilation ◽  
Lower Vertebrates ◽  
And Performance ◽  
Respiratory Medium ◽  
Density Of Water ◽  
Rigid Shell ◽  
Exchange Surface ◽  
Ventilation And Perfusion

The design of vertebrate respiratory systems has been subject to two major sets of constraints. The first is the need to satisfy the primary function of the respiratory surface as an organ of gas exchange. These constraints include the need to reduce the diffusion gradient between air and blood while providing adequate ventilation and perfusion of the exchange surface. The second set of constraints arises from the need to satisfy other physiological, environmental, and behavioral demands. The constraints imposed by the low oxygen content and high density of water as a respiratory medium, the rigid shell of turtles, and the long thin body of snakes, as well as the life-style and habitat of diving animals, are all used to illustrate the unique features of several experiments in the design and performance of respiratory pumps. It is shown, however, that despite the tremendous diversity that exists among species, all mechanisms allow ventilation to be powered by surprisingly similar changes in pulmonary pressure.

scholarly journals Design and Performance Analysis of Hybrid SELBOX Junctionless FinFET

2019 ◽  
pp. 25-32
Keyword(s):  
Current Gain ◽  
Thin Body ◽  
Feature Size ◽  
Self Heating ◽  
Gate Capacitance ◽  
Inversion Region ◽  
And Performance ◽  
Better Than ◽  
Analog Parameters ◽  
Intrinsic Gain

In this work, the performance of selective buried oxide junction-less (SELBOX-JL) transistor at a FinFET structure is analysed using numerical simulations. The proposed structure exhibits better thermal resistance (RTH), which is the measure of the self-heating effect (SHE). The DC and analog performances of the proposed structure were studied and compared with the conventional and hybrid (or inverted-T) JLFinFETs (JLTs). The ION of the hybrid SELBOX- JLFinFET is 1.43x times better than the ION of the JLT due to the added advantage of different technologies, such as 2D-ultra-thin-body (UTB), 3D-FinFET, and SELBOX. The proposed device is modeled using sprocess and simulation study is carried using sdevice. Various analog parameters, such as transconductance (gm), transconductance generation factor (TGF = gm/IDS), unity current gain frequency (fT), early voltage (VEA), total gate capacitance (Cgg), and intrinsic gain (A0), are evaluated. The proposed device with a minimum feature size of 10nm exhibited better TGF, fT, VEA, and A0 in the deep-inversion region of operation.

Sub 50nm Strained n-FETs Formed on Silicon-Germanium-on-Insulator Substrates and the Integration of Silicon Source/Drain Stressors

2007 ◽  
Vol 995 ◽  
Author(s):  
Grace Huiqi Wang ◽  
Eng-Huat Toh ◽  
Keat-Mun Hoe ◽  
S. Tripathy ◽  
Guo-Qiang Lo ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Silicon Germanium ◽  
Tensile Strain ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Thin Body ◽  
Uniaxial Tensile ◽  
Silicon Source ◽  
D Region ◽  
And Performance

AbstractSilicon (Si) source and drain (S/D) regions have been successfully integrated in thin-body silicon-germanium-on-insulator (SGOI) n-FETs. The selectively grown Si S/D induces uniaxial tensile strain in the SiGe channel. Devices with gate length LG down to 50 nm were fabricated. The Si S/D gives rise to 40% higher saturation drive current IDsat for transistors fabricated on Si0.60Ge0.40-on-insulator substrates. For n-FETs fabricated on Si0.75Ge0.25-on-insulator substrates, a 27% IDsat enhancement was observed. Lattice mismatch between the silicon S/D region and the SiGe channel was exploited to induce lateral tensile strain and vertical compressive strain in the channel, leading to enhancement in electron mobility. Analyses of contributions from the tensile strain to mobility enhancement and performance improvement are discussed

scholarly journals Design, Fabrication, and Performance Analysis of a Vertically Suspended Soft Manipulator

2021 ◽  
Vol 15 (5) ◽  
pp. 696-705
Author(s):  
Mohamed Tahir Shoani ◽  
Mohamed Najib Ribuan ◽  
Ahmad Athif Mohd Faudzi ◽  
◽  
◽  
...  
Keyword(s):  
Closed Loop ◽  
Horizontal Displacement ◽  
Thin Body ◽  
Light Weight ◽  
Flexible Materials ◽  
Pneumatic Muscles ◽  
Continuum Manipulators ◽  
Thin Plastic ◽  
And Performance ◽  
Soft Manipulator

Soft continuum manipulators are comprised of flexible materials in a serpentine shape. Such manipulators can be controlled mechanically through tendons or pneumatic muscles. Continuum manipulators utilizing tendons are traditionally formed in a thick cross section, which presents limitations in achieving a high bending range as well as difficulties for storage and transportation. This study introduces a continuum manipulator comprised of two thin plastic bands and driven by a tendon to provide a bending action. The manipulator’s thin body form enables it to be rolled up for storage and transportation. Experimental results on different section lengths show the possibility of achieving a horizontal displacement of up to 34% of the bending-segment’s length, and a full closed-loop curvature for most segments. However, the results also indicated an elongation of the tip paths owing to gravity. These results, in addition to the manipulator’s flexibility and light weight features, confirm its suitability for applications in space and underwater environments.

scholarly journals Comparative Analysis of Nutritional Value ofOreochromis niloticus(Linnaeus), Nile Tilapia, Meat from Three Different Ecosystems

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Fanuel Jim ◽  
Penina Garamumhango ◽  
Colin Musara
Keyword(s):  
Chemical Composition ◽  
Oxygen Content ◽  
Water Hyacinth ◽  
Nile Tilapia ◽  
Dry Matter ◽  
Atomic Absorption Spectrophotometry ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Lake Kariba ◽  
Density Of Water

Determination of protein, lipid, and mineral content of fish meat is necessary to ensure that it meets requirements for food regulations and commercial specifications. The objective of the present study was to determine the chemical composition ofOreochromis niloticus(L.), Nile tilapia, under three different ecosystems: (1) high pollution and high density ofEichhornia crassipes, that is, water hyacinth (Lake Chivero), (2) medium pollution and medium density of water hyacinth (Lake Manyame), and (3) low pollution and low density of water hyacinth (Lake Kariba). Dry matter, protein, lipids, and ash were evaluated by proximate analysis. Minerals were determined by atomic absorption spectrophotometry and pH was determined by a pH meter. Lake Kariba fish had the highest percentage of dry matter, protein, and ash. These qualities were correlated to low levels of pollutants and high oxygen content in the harvest waters. The phosphorus content of fish from Lake Chivero was very high, in tandem with phosphate levels in the harvest waters. In addition, water from Lake Chivero had an alkaline pH, high nitrate, and low oxygen content. The results suggest that effluent from sewage works and fertilizer industries caused pollution and proliferation of water hyacinth, contributing to pervasion of the chemical composition of fish.

scholarly journals An Overview of Biochar Production and Biochar Producing Stoves in Bangladesh

2020 ◽  
pp. 14-31
Author(s):  
Md. Sadekur Rahman ◽  
Md. Enamul Haque ◽  
Md. Rubayet Al Ferdous Noman
Keyword(s):  
Review Paper ◽  
Policy Framework ◽  
Access To Information ◽  
Positive Perception ◽  
Low Oxygen ◽  
Rural Farmers ◽  
Sustainable Environment ◽  
The Status ◽  
Knowledge And Attitude ◽  
And Performance

Biochar is not a newly invented technology; rather its relevance and efficacy have recently come to the front burner. Naturally, it is deposited in the soil through forest and grassland fires. Interestingly, biochar is also produced from biomass by zero or low oxygen environment. However, biochar has gained an international research interest and offers ample scope for further investigations on biochar and biochar producing cooking stove. The present review paper mainly focuses on the status of biochar production and biochar producing stoves with specific emphasis on the status of biochar production technology and the perception, knowledge, and attitude towards biochar production and utilization; use and performance of biochar producing cooking stoves; and problems encountered in biochar production and utilization. Having observed positive perception, and attitude as well as an appreciable knowledge of rural farmers in biochar production and utilization the paper emphasizes the incorporation of a policy framework, training and enhanced access to information for higher agriculture use of biochar and sustainable environment.

Integration and Performance Improvements of Silicon Nanocrystal Memories

2004 ◽  
Vol 830 ◽  
Author(s):  
T. Hiramoto ◽  
I. Kim ◽  
M. Saitoh ◽  
K. Yanagidaira
Keyword(s):  
State Of The Art ◽  
Thin Body ◽  
Double Gate ◽  
Silicon Nanocrystal ◽  
Performance Improvements ◽  
Device Structures ◽  
Non Volatile Memory ◽  
Nanocrystal Memory ◽  
And Performance ◽  
Memory Characteristics

ABSTRACTThe silicon nanocrystal memory, that is one of the most promising devices for future non-volatile memory, is extensively investigated by experiments and simulation. The silicon nanocrystal memory cells are successfully integrated using the state-of-the-art 0.13 μm DRAM technology. The mechanism of the two-bit-per-cell operation, that is one of the unique features of silicon nanocrystal memory, is investigated and it is shown that the degree of DIBL determines the read scheme of the two-bit-per-cell operation. Moreover, the dependences of memory characteristics on device structures are examined by fabrication and measurements and it is found that the ultra-thin-body SOI and double-gate structures have better memory characteristics.

scholarly journals Evolution of the oxygen sensitivity of cytochrome c oxidase subunit 4

2015 ◽  
Vol 308 (4) ◽  
pp. R305-R320 ◽  
Author(s):  
K. M. Kocha ◽  
K. Reilly ◽  
D. S. M. Porplycia ◽  
J. McDonald ◽  
T. Snider ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Disulfide Bridge ◽  
Structural Features ◽  
Fine Tuning ◽  
Fish Cell ◽  
Low Oxygen ◽  
Atp Binding Site ◽  
Sequence Variations ◽  
Lower Vertebrates

Vertebrates possess two paralogs of cytochrome c oxidase (COX) subunit 4: a ubiquitous COX4-1 and a hypoxia-linked COX4-2. Mammalian COX4-2 is thought to have a role in relation to fine-tuning metabolism in low oxygen levels, conferred through both structural differences in the subunit protein structure and regulatory differences in the gene. We sought to elucidate the pervasiveness of this feature across vertebrates. The ratio of COX4-2/4-1 mRNA is generally low in mammals, but this ratio was higher in fish and reptiles, particularly turtles. The COX4-2 gene appeared unresponsive to low oxygen in nonmammalian models (zebrafish, goldfish, tilapia, anoles, and turtles) and fish cell lines. Reporter genes constructed from the amphibian and reptile homologues of the mammalian oxygen-responsive elements and hypoxia-responsive elements did not respond to low oxygen. Unlike the rodent ortholog, the promoter of goldfish COX4-2 did not respond to hypoxia or anoxia. The protein sequences of the COX4-2 peptide showed that the disulfide bridge seen in human and rodent orthologs would be precluded in other mammalian lineages and lower vertebrates, all of which lack the requisite pair of cysteines. The coordinating ligands of the ATP-binding site are largely conserved across mammals and reptiles, but in Xenopus and fish, sequence variations may disrupt the ability of the protein to bind ATP at this site. Collectively, these results suggest that many of the genetic and structural features of COX4-2 that impart responsiveness and benefits in hypoxia may be restricted to the Euarchontoglires lineage that includes primates, lagomorphs, and rodents.

scholarly journals Bias-controlled multi-functional transport properties of InSe/BP van der Waals heterostructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sang-Hoo Cho ◽  
Hanbyeol Jang ◽  
Heungsoon Im ◽  
Donghyeon Lee ◽  
Je-Ho Lee ◽  
...  
Keyword(s):  
Performance Optimization ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Thin Body ◽  
Channel Resistance ◽  
Operational Characteristics ◽  
Wide Range ◽  
Multiple Devices ◽  
And Performance ◽  
Low Dimensional

AbstractVan der Waals (vdW) heterostructures, consisting of a variety of low-dimensional materials, have great potential use in the design of a wide range of functional devices thanks to their atomically thin body and strong electrostatic tunability. Here, we demonstrate multi-functional indium selenide (InSe)/black phosphorous (BP) heterostructures encapsulated by hexagonal boron nitride. At a positive drain bias (VD), applied on the BP while the InSe is grounded, our heterostructures show an intermediate gate voltage (VBG) regime where the current hardly changes, working as a ternary transistor. By contrast, at a negative VD, the device shows strong negative differential transconductance characteristics; the peak current increases up to ~5 μA and the peak-to-valley current ratio reaches 1600 at VD = −2 V. Four-terminal measurements were performed on each layer, allowing us to separate the contributions of contact resistances and channel resistance. Moreover, multiple devices with different device structures and contacts were investigated, providing insight into the operation principle and performance optimization. We systematically investigated the influence of contact resistances, heterojunction resistance, channel resistance, and the thickness of BP on the detailed operational characteristics at different VD and VBG regimes.

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