Key Structural Research Articles

Pathogenic mechanism analysis of cochlear key structural lesion and phonosensitive hearing loss.

Due to ethical issues and the very fine and complex structure of the cochlea, it is difficult to directly perform experimental measurement on the human cochlea. Therefore, the finite element method has become an effective and replaceable new research means. Accurate numerical analysis on human ear using finite element method can provide better understanding of sound transmission and can be used to assess the influence of diseases on hearing and to treat hearing loss. In this research, a three-dimensional (3D) finite element model (FEM) of the human ear of cochlea was presented to investigate the destruction of basilar membrane (BM), round window (RW) sclerosis and perilymph fistula, the key structures of the cochlea, and analyze the effects of these abnormal pathological states in the cochlea on cochlear hearing, resulting in the changes in cochlear sense structure biomechanical behavior and quantitative prediction of the degree and harm of the disorder to the decline of human hearing. Therefore, this paper can deepen reader's understanding of the cochlear biomechanical mechanism and provide a theoretical foundation for clinical otology.

Effect of key structure and working condition parameters on a compact flat-evaporator loop heat pipe for chip cooling of data centers

Loop heat pipe has the advantages of large heat transfer coefficient without extra power input, therefore it has a good application potential in chip cooling of data centers. In this paper, a compact flat-evaporator loop heat pipe is designed and the effects of key structural parameters and working conditions on the dynamic and steady-state performance are studied. The results show that increasing heat load or the filling ratio, arranging vapor channels in the middle of the wick (rather than at the bottom) or lengthening the condenser can all reduce the temperature fluctuation; A small inclination angle of 5° and 10° can reduce the temperature fluctuation and the stable temperature, while large inclination angle of 15° will instead bring higher stable temperature; When the heat load increases step by step, the stable temperature (average temperature for fluctuation conditions) decreases and then increases for all filling ratios and structures; Minimized thermal resistance is achieved by optimizing wick and condenser structure under low and high heat load, respectively.

Optimization of Key Hydraulic Structure Parameters of a New Type of Water–Pesticide Integrated Sprinkler Based on Response Surface Experiment

To meet the requirements of trellis grape crop root irrigation, spraying pesticides on branches and leaves, an integrated sprinkler was designed, which relies on the flow pressure to change the irrigation water and spray pesticide working modes. The structural parameters that affect the hydraulic performance were selected based on the working principle of the sprinkler. The key parameters for the irrigation mode included diversion hole inclination angle, refractive cone angle, refractive cone length, and cone hole distance. The key parameters for the spray pesticide mode included diversion chute width, the number of diversion chutes, the diversion chute inclination angle, the rotary acceleration chamber height, and the nozzle outlet cylindrical section length. The central composite design response surface tests of the water–pesticide integrated sprinkler were carried out; the analysis of variance and regression analysis were selected; the main influence rules and interactions of key structural parameters on irrigation performance and pesticide spraying performance of sprinkler irrigation system were obtained. The optimal parameters of the water–pesticide integrated sprinkler were: the diversion hole inclination angle is 20.8°, the refractive cone angle is 123.7°, the refractive cone length is 8.8 mm, the cone hole distance is 3.6 mm, the diversion chute width is 2.5 mm, the number of diversion chutes is 2, the diversion chute inclination angle is 10°, the rotary acceleration chamber height is 1.3 mm, and the nozzle outlet cylindrical section length is 0.7 mm. The irrigation hydraulic performance of the wetted radius is 3.4 m, the average irrigation application rate is 0.65 mm/h, and the uniformity coefficient is 88%. The spraying pesticide performance of the droplet volume mid-diameter is 200.2 μm, the droplet spectrum width is 2.2, and the droplet coverage is 9.4%.

Key Structure Design and Experiment of Air-Suction Vegetable Seed-Metering Device

The air-suction precision seed-metering device is prone to the instability of the seed adsorption state, which arises from blockage of the suction hole and leads to uneven seeding. This paper analyzed and determined key structural parameters of the seed-metering plate, then established an adsorption mechanics model of the seed during the migration process and designed the key structure of the air-suction seed-metering device with the aim of improving the uniformity of high-speed direct seeding of vegetables. Furthermore, we used the DEM-CFD coupling method to analyze the influence of the law of seeds on the change of the flow field with different hole types. Results showed that the turbulent kinetic energy (202.65 m2∙s−2) and the coupling force to the seeds (0.029 N) of the B-type hole are the largest, which is the best fluid domain structure for the suction hole of the seed-metering plate. Moreover, we used Adams to analyze the meshing process between the knock-out wheel and the seed-metering plate, affirming the rationality of the knock-out wheel design. Finally, in order to improve the working efficiency of the seed-metering device, we performed one-factor and response surface experiments of seeding performance using the air-suction seed-metering device designed with the optimized structure as the experimental object. Analysis of the influence of weights across each factor on the experimental performance evaluation indicators revealed an optimal combination of seeding performance parameters in the air-suction seed-metering device, namely a seed-throwing angle of 13°, a working speed of 14.5 km/h, and negative pressure of 3.1 kPa. Results from verification experiments revealed the corresponding experimental indicators, namely qualified, multiple, and missing indexes of 95.9, 1.2%, and 2.9%, respectively.

Optimization and experiment on key structural parameters of no-tillage planter with straw-smashing and strip-mulching

Accelerate the quality of smashed-straw laying and enhance the effect of seed-bed arranging for no-tillage planter with straw-smashing and strip-mulching in full stubble covered paddy have become imperative in implementing modern conservation tillage. Considering the perfect operating performance (passability and stability) of the developed no-tillage planter, this study intends to optimize the structure design of smashed-straw diversion device and strip-rotary tillage device. Dynamics equations of smashed straw and kinematics models of rotary blades were established through theoretical analysis, and the principal factors that affecting straw strip-laying quality and seed-bed arranging effect were specified. The influence of out-enlarge angle (η) and slide-push angle (γ) of the diversion device on the coefficient of variation (ζ1) of cover-straw width, and the influence of rotary tillage-blade number (N) and configuration in a single rotary plane on the broken rate (ζ2) of strip soil were completely analyzed. And then, based on the systematic analysis and integrated scheme, operating performance and field verification tests using the optimized no-tillage planter were thoroughly performed. The results of the performance tests indicated that the out-enlarge angle (η) had a highly significant influence on the coefficient of variation (ζ1), and the slide-push angle (γ) had a significant influence on (ζ1). The rotary tillage-blade number (N) had a highly significant influence on the broken rate (ζ2), and the slide-push angle (γ) had a significant influence on (ζ2). The obtained optimal combination of these key structure parameters through comprehensive analysis was η = 45°, γ = 40°, and N = 4. Field verification test results indicated that the optimized no-tillage planter achieved mean values of ζ1 = 10.47% and ζ2 = 90.95%, which satisfied the relevant operation quality and cultivation agricultural requirement of conservation tillage equipment, and provided technical references for developing the similar no-tillage planter of straw crushing and returning. Keywords: no-tillage planter, smashed-straw laying, strip rotary tillage, optimization test DOI: 10.25165/j.ijabe.20211403.5887 Citation: Shi Y Y, Wang X C, Hu Z C, Gu F W, Wu F, Chen Y Q. Optimization and experiment on key structural parameters of no-tillage planter with straw-smashing and strip-mulching. Int J Agric & Biol Eng, 2021; 14(3): 103–111.

Optimization and experiment on key structural parameters of no-tillage planter with straw-smashing and strip-mulching

Accelerate the quality of smashed-straw laying and enhance the effect of seed-bed arranging for no-tillage planter with straw-smashing and strip-mulching in full stubble covered paddy have become imperative in implementing modern conservation tillage. Considering the perfect operating performance (passability and stability) of the developed no-tillage planter, this study intends to optimize the structure design of smashed-straw diversion device and strip-rotary tillage device. Dynamics equations of smashed straw and kinematics models of rotary blades were established through theoretical analysis, and the principal factors that affecting straw strip-laying quality and seed-bed arranging effect were specified. The influence of out-enlarge angle (η) and slide-push angle (γ) of the diversion device on the coefficient of variation (ζ1) of cover-straw width, and the influence of rotary tillage-blade number (N) and configuration in a single rotary plane on the broken rate (ζ2) of strip soil were completely analyzed. And then, based on the systematic analysis and integrated scheme, operating performance and field verification tests using the optimized no-tillage planter were thoroughly performed. The results of the performance tests indicated that the out-enlarge angle (η) had a highly significant influence on the coefficient of variation (ζ1), and the slide-push angle (γ) had a significant influence on (ζ1). The rotary tillage-blade number (N) had a highly significant influence on the broken rate (ζ2), and the slide-push angle (γ) had a significant influence on (ζ2). The obtained optimal combination of these key structure parameters through comprehensive analysis was η = 45°, γ = 40°, and N = 4. Field verification test results indicated that the optimized no-tillage planter achieved mean values of ζ1 = 10.47% and ζ2 = 90.95%, which satisfied the relevant operation quality and cultivation agricultural requirement of conservation tillage equipment, and provided technical references for developing the similar no-tillage planter of straw crushing and returning. Keywords: no-tillage planter, smashed-straw laying, strip rotary tillage, optimization test DOI: 10.25165/j.ijabe.20211403.5887 Citation: Shi Y Y, Wang X C, Hu Z C, Gu F W, Wu F, Chen Y Q. Optimization and experiment on key structural parameters of no-tillage planter with straw-smashing and strip-mulching. Int J Agric & Biol Eng, 2021; 14(3): 103–111.

Inversion method of the key structure parameters of light screen array measurement system using genetic algorithm

To effectively improve the measurement accuracy of the light screen array measurement system (LSA for short) in the evaluation of continuous rapid-firing weapon, the paper presents an inversion method to obtain the key structure parameters of LSA based on genetic algorithm. First, we systematically introduce a measurement model based on the key structure parameters of the LSA. Second, we establish an objective function through the validation of the measurement results. Next, an inversion method is derived to generate many groups of structural parameters within the allowable error range. Finally, we can adopt a genetic algorithm to obtain a group of the key structural parameters which are the closest to their truth value. Through simulations and experiments, results show that the measurement model is corrected because of the key structural parameters through the inversion, and thus the accuracy of the LSA is effectively improved.

From shared intentionality to moral obligation? Some worries

ABSTRACTAccording to Tomasello’s natural history of human morality, morality's key structures come into being in the dyadic joint action of early human hunters. Such joint action, Tomasello claims, involves the generation of a new entity, a “joint agent,” and brings with it insight into the agent-independence of agential roles. These two features are, Tomasello argues, decisive for the inception of early humans’ “respect”-based proto-morality. The key structures at work are then, he claims, “scaled up” in the “group morality” of modern humans. I raise three worries about the narrative at the level of early humans’ proto-morality. These concern the content of proto-moral “respect,” the role of language or proto-language, and the limits of focusing on dyads. In a final step, I express the concern that Tomasello’s construal of the “scaling up” process appears to lose the key structural features of respect, as it seems unable to distinguish social and moral norms.

An Emerging Paradigm of Structural Indicators to Examine System Supports for Children’s and Adolescents’ Education and Wellbeing

This article argues that a distinct focus on background system supports can take place through structural indicators, at both national and institutional levels. Development of structural indicators is already taking place for the UN right to the highest attainable standard of health and in recent publications of the European Commission in education contexts. Structural indicators are generally framed as potentially verifiable yes/no answers, they address whether or not key structures, mechanisms or principles are in place in a system. As relatively enduring features or key conditions of a system, they are, however, potentially malleable. A systems of care focus is resonant with structural indicators and moves beyond isolated, fragmented service provision to an integrated whole system of supports. Structural indicators can aid such strategic planning for systems of care. This focus on structural indicators goes beyond a traditional qualitative/quantitative distinction and beyond reliance on sharing models of good practice to seek to identify key structural conditions for good practice. Structural indicators offer a bridge between central strategic direction and local flexibility. The weight of evidence required for a structural indicator may depend on its scope and purpose. Structural indicators can combine a rights, principles and strategic policy based focus with one that is informed by implementation science issues and evidence. They offer a policy relevant bridge between research and practice.

New design architecture of a 3-DOF vibratory gyroscope with robust drive operation mode and implementation

This paper presents new gyroscope design architecture with the complete 2-DOF drive and 1-DOF sense mode oscillators that enable the implementation of reduced drive bandwidth without significantly decreasing the sense-to-drive mass ratio of the device. The mechanical structure has an additional anchoring of the decoupling frame mass which allows for the specification of the drive mode resonances and the coupling between the masses independent of the sense mode frequency. This feature eliminates the requirement of an increased design space for realizing a high operational frequency device with robust operation. In addition to this, a reduction in the bandwidth enabled by the additional anchor, leads to the increase in drive mass amplitude, which in turn results in an increased mechanical gain. With this arrangement, the actuation voltage can be further reduced for the same drive displacement as of non-anchored structure. This device has been mathematically modelled considering decoupled frame anchoring effect, designed and then fabricated by using the economical UV-LIGA technology with nickel as a key structural layer of 8 µm thickness; with an overall reduced key structure size of 2.13 by 1.93 mm. Experimental characterization demonstrates the two drive resonances at 8.55 and 10.6 kHz with a bandwidth of 1.0 kHz and the sense mode resonance at 9.2 kHz.

Molecular dynamics study of the opening mechanism for DNA polymerase I.

During DNA replication, DNA polymerases follow an induced fit mechanism in order to rapidly distinguish between correct and incorrect dNTP substrates. The dynamics of this process are crucial to the overall effectiveness of catalysis. Although X-ray crystal structures of DNA polymerase I with substrate dNTPs have revealed key structural states along the catalytic pathway, solution fluorescence studies indicate that those key states are populated in the absence of substrate. Herein, we report the first atomistic simulations showing the conformational changes between the closed, open, and ajar conformations of DNA polymerase I in the binary (enzyme∶DNA) state to better understand its dynamics. We have applied long time-scale, unbiased molecular dynamics to investigate the opening process of the fingers domain in the absence of substrate for B. stearothermophilis DNA polymerase in silico. These simulations are biologically and/or physiologically relevant as they shed light on the transitions between states in this important enzyme. All closed and ajar simulations successfully transitioned into the fully open conformation, which is known to be the dominant binary enzyme-DNA conformation from solution and crystallographic studies. Furthermore, we have detailed the key stages in the opening process starting from the open and ajar crystal structures, including the observation of a previously unknown key intermediate structure. Four backbone dihedrals were identified as important during the opening process, and their movements provide insight into the recognition of dNTP substrate molecules by the polymerase binary state. In addition to revealing the opening mechanism, this study also demonstrates our ability to study biological events of DNA polymerase using current computational methods without biasing the dynamics.

Research on the Optimal Design of a Pilot Valve Controlling Cut-Off Valve

The cut-off valve based on pilot valve controlling is a new kind of valve which opens and closes fast and has low driving energy consumption. Because of the complexity of the internal flow and uncertainty of the internal pressure, there is uncertainty in the design of the key structure. We simulate the whole opening process of the valve under different key structural dimensions with Fluent Dynamic Mesh and UDFs, and we do experiments to authenticate simulation results. The turn-on time we get from the simulation is the same as that from experiments under the valves actual operating conditions, in other words, the simulation results are correct, so we can identify the valve flow and get the internal pressure data which provides a reliable basis for the design of the key structural dimensions.

Water Structure at the Potassium Channel Gate: The Importance of the Prolines in the PVPV Sequence, as Shown by Computational Mutations, and the Role of a Histidine in Gating

Conservation of the PVPV sequence at the potassium channel gate has not been well understood. Quantum computations (optimization at HF/4-22GSP level) of the gate of the Kv1.2 channel that are presented here show that the proline-proline distances (ring atoms) are preserved as the ion moves through the gate. This calculation is supplemented by mutating one of the prolines to valine (P407V, 2A79 pdb numbering for all residues in this abstract) in the computation, producing a PVVV sequence. Water structure changed dramatically, as the protein backbone moved inward nearly 3A, effectively closing the channel; the proline ring N-N distance between diagonally opposite prolines dropped from 14.3 A (distance from optimization: X-ray distance = 15.6A) to 11.4 A, too small to allow passage of a hydrated K+. This suggests that the prolines play a key structural role, modulating both protein and water structure. Furthermore, protonation of H418 may close the channel. Protonation of this histidine shows it moving toward the gate by about 3 A, which should close the gate electrostatically, while deprotonation opens the gate. Protonation was calculated with two added protons, the other being accepted by E142 of the T1 intracellular moiety. When deprotonated, the histidine does not move as much as 1A from the X-ray position in the optimization, and is linked to E142; this accounts for the known importance of the T1 segment in gating. E136, also of T1, could accept a third proton. There is a salt bridge structure including these residues similar to the one occupying a key position in the proton pathway in the Hv1 channel.

Imaging and genetics advances in understanding geriatric depression

Over a decade has passed since publication of the vascular depression hypothesis that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes (Alexopoulos et al, 1997). This construct has catalyzed much research, largely focused on structural neuroimaging, clinical neuropsychology, and in last few years, genetics and cognitive neuroscience. Recent investigations have combined advanced neuroimaging techniques and genetic analyses to delineate key structural and functional findings in late-life depression (LLD). Vascular brain changes on imaging studies have long been associated with LLD. Genetic analysis of vascular changes is an emerging field, and recent work in older populations has focused on polymorphisms associated with (1) psychiatric disease in younger adults or (2) vascular risk factors. We have previously reported links between BDNF (brain-derived neurotrophic factor) polymorphisms (Taylor et al, 2008) and serotonin transporter-linked polymorphic region (5HTTLPR) polymorphisms (Steffens et al, 2008) and white matter hyperintensity (WMH) volumes, supporting theories that these genes also have a role in LLD. The notion that WMHs are vascular in nature led our group to explore relationships between WMH volume and genes associated with systemic vascular risk. These include renin–angiotensin system genes, such as the angiotensin II receptor, vascular types 1 and 2 (AGTR1 and AGTR2) genes. In addition to reports linking AGTR1 polymorphisms to LLD outcomes, we have also found gender-specific associations between AGTR polymorphisms and WMH progression (Taylor et al, 2009). Similarly, the methylenetetrahydrofolate reductase (MTHFR) gene, another vascular risk gene associated with folate and homocysteine metabolism, may be associated with LLD, and we are examining MTHFR and other genes related to folate metabolism in the occurrence of white matter lesions in LLD. Our studies continue to examine the role of vascular risk genes in LLD, focusing on their influence on brain structure and cognition. Consistent with the vascular depression hypothesis is the notion the LLD is associated with disruption in frontal-striatal circuitry. These abnormalities in the prefrontal cortex, striatum, and frontal-striatal white matter tracks are also likely related to genetic differences. A previous study noted a link between the 5HTTLPR short allele and caudate volume in LLD. We recently reported an interaction between two genes, COMT (catechol-O-methyltransferase) and MTHFR, and putamen volume reduction in LLD (Pan et al, 2009). Identification of genes associated with prefrontal cortical structure and function remains an active area of inquiry. Beyond the vascular depression hypothesis, another avenue of genetic/neuroimaging LLD research examines the observed link between depression and later dementia. The hippocampus is a key structure related to both LLD pathophysiology and increased dementia risk. The APOE gene is associated with both depression and Alzheimer's disease, and APOE genotype has been associated with specific shape differences in geriatric depression (Qiu et al, 2009). Allelic differences in the 5HTTLPR gene have also been associated with hippocampal volume in LLD by several groups. Advances in both neuroimaging technologies and genetic assessment allow us to investigate the pathophysiology of affective disorders. Existing paradigms of vascular depression and depression as dementia risk make LLD ideally suited for future genetic/imaging studies.