Failure analysis of simple overlap bonding joints and numerical investigation of the adhered tip geometry effect on the joint strength

This study was carried out in two stages. In the first step, a numerical study was performed to verify the previous experimental study. In accordance with the previous experimental study data, single lap joints models were created using the ANSYS finite element analysis program. Then, nonlinear stress and failure analyses were performed by applying the failure loads obtained in the experimental study. The maximum stress theory was used to find finite element failure loads of the single lap joints models. As a result of the finite element analysis, an approximate 80 % agreement was found between experimental and numerical results. In the second step of the study, in order to increase the bond strength, different overlap end geometry models were produced and peel and shear stresses in the adhesive layer were compared according to the reference model. As a result of the analyses, significant strength increases were calculated according to the reference model. The strength increase in model 3 and model 5 was found to be 80 % and 67 %, respectively, relative to the reference model.

In silico investigation of ligand-regulated palladium-catalysed formic acid dehydrative decomposition under acidic conditions

In silico investigation of ligand-regulated palladium-catalysed formic acid dehydrative decomposition to carbon monoxide under acidic conditions was conducted. Two types of bidentate tertiary phosphine ligands were selected on the basis of previous experimental study. And the promoting effect of para-toluenesulfonic acid (PTSA) was specifically investigated. The pyridyl group implanted in pytbpx ligand is found to mainly contribute on enhancing the activity of palladium catalyst. The PTSA promoter displays specific role for regenerating active species and supressing dehydrogenation during Pd-pytbpx/Pd-dtbpx catalysed dehydration process. CO releasing process catalysed by Pd-dtbpx also facilitated by adding PTSA. According to the mechanism hereby supposed, introducing electron-withdrawing substitution at para-position of pyridyl rings may further improve the dehydrative decomposition activity of Pd-pytbpx.

Computational design of SARS-CoV-2 peptide binders with better predicted binding affinities than human ACE2 receptor

SARS-CoV-2 is coronavirus causing COVID-19 pandemic. To enter human cells, receptor binding domain of S1 subunit of SARS-CoV-2 (SARS-CoV-2-RBD) binds to peptidase domain (PD) of angiotensin-converting enzyme 2 (ACE2) receptor. Employing peptides to inhibit binding between SARS-CoV-2-RBD and ACE2-PD is a therapeutic solution for COVID-19. Previous experimental study found that 23-mer peptide (SBP1) bound to SARS-CoV-2-RBD with lower affinity than ACE2. To increase SBP1 affinity, our previous study used residues 21–45 of α1 helix of ACE2-PD (SPB25) to design peptides with predicted affinity better than SBP1 and SPB25 by increasing interactions of residues that do not form favorable interactions with SARS-CoV-2-RBD. To design SPB25 with better affinity than ACE2, we employed computational protein design to increase interactions of residues reported to form favorable interactions with SARS-CoV-2-RBD and combine newly designed mutations with the best single mutations from our previous study. Molecular dynamics show that predicted binding affinities of three peptides (SPB25Q22R, SPB25F8R/K11W/L25R and SPB25F8R/K11F/Q22R/L25R) are better than ACE2. Moreover, their predicted stabilities may be slightly higher than SBP1 as suggested by their helicities. This study developed an approach to design SARS-CoV-2 peptide binders with predicted binding affinities better than ACE2. These designed peptides are promising candidates as SARS-CoV-2 inhibitors.

Modeling Post-Scratching Locomotion with Two Rhythm Generators and a Shared Pattern Formation

This study aimed to present a model of post-scratching locomotion with two intermixed central pattern generator (CPG) networks, one for scratching and another for locomotion. We hypothesized that the rhythm generator layers for each CPG are different, with the condition that both CPGs share their supraspinal circuits and their motor outputs at the level of their pattern formation networks. We show that the model reproduces the post-scratching locomotion latency of 6.2 ± 3.5 s, and the mean cycle durations for scratching and post-scratching locomotion of 0.3 ± 0.09 s and 1.7 ± 0.6 s, respectively, which were observed in a previous experimental study. Our findings show how the transition of two rhythmic movements could be mediated by information exchanged between their CPG circuits through routes converging in a common pattern formation layer. This integrated organization may provide flexible and effective connectivity despite the rigidity of the anatomical connections in the spinal cord circuitry.

A Volumetric Analysis of the 1H NMR Chemical Shielding in Supramolecular Systems

The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host–guest complexes. Its theoretical counterpart, that is, the 1H NMR chemical shielding affected by the solvent (1H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted 1H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The 1H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the 1H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.

Computational Study of Compartment Size Effects on Backdraft Intensity

A computational study was performed to evaluate the effects of compartment size on backdraft intensity. The compartment sizes were selected such that each direction was enlarged by a factor of 2, 2.5, 2.625, and 3 based on the reduced-scale compartment of a previous experimental study. A fire dynamics simulator was used for the computation, and a large eddy simulation and a mixing-controlled fast chemistry combustion model were adopted. Results revealed that the overall equivalence ratio defined by the amounts of fuel inside the compartment and oxygen induced from the opening had similar values at the moment when the air reached the inside wall. The fuel–air mixing inside the compartment was found to be achieved more rapidly with a decreased compartment size. The peaks of pressure and heat release rate inside the compartment increased with an increase in compartment size. However, these peaks were found to increase exponentially with an increase in the ratio of the compartment volume and opening size, and the correlation showed a very high R-squared value.

External heat transfer enhancement of a beta-type Stirling engine with fins as regenerator

The Stirling engine is an externally heat engine closed loop with a high theoretical performance and low emissions compared to other conventional engines. This property nowadays becomes very advantageous due to its multi-fuel capacity including solar, biogas and geothermal energy. In this study, a numerical investigation of the effect of a circular, pin, and rectangular fins on the performance of the Stirling engine is introduced. The 3D CFD model was performed and validated with previous experimental study. The power output, heat transfer rate and efficiency were studied for all cases of fins. The results indicated a close agreement between the numerical and the experimental results with average difference for power of the engine approximately around 2.8%. The efficiency decrease with the increase of the rotational speed of the engine and the highest efficiency is indicated for rectangular fins.

Validating N-body code chrono for granular DEM simulations in reduced-gravity environments

ABSTRACT The Discrete Element Method (DEM) is frequently used to model complex granular systems and to augment the knowledge that we obtain through theory, experimentation, and real-world observations. Numerical simulations are a particularly powerful tool for studying the regolith-covered surfaces of asteroids, comets, and small moons, where reduced-gravity environments produce ill-defined flow behaviours. In this work, we present a method for validating soft-sphere DEM codes for both terrestrial and small-body granular environments. The open-source code chrono is modified and evaluated first with a series of simple two-body-collision tests, and then, with a set of piling and tumbler tests. In the piling tests, we vary the coefficient of rolling friction to calibrate the simulations against experiments with 1 mm glass beads. Then, we use the friction coefficient to model the flow of 1 mm glass beads in a rotating drum, using a drum configuration from a previous experimental study. We measure the dynamic angle of repose, the flowing layer thickness, and the flowing layer velocity for tests with different particle sizes, contact force models, coefficients of rolling friction, cohesion levels, drum rotation speeds, and gravity levels. The tests show that the same flow patterns can be observed at the Earth and reduced-gravity levels if the drum rotation speed and the gravity level are set according to the dimensionless parameter known as the Froude number. chrono is successfully validated against known flow behaviours at different gravity and cohesion levels, and will be used to study small-body regolith dynamics in future works.

Effects of rumination on unwanted intrusive thoughts: A replication and extension

Studies indicate that rumination might play a role in obsessive–compulsive disorder. In a previous experimental study, rumination about an unwanted intrusive thought (UIT) maintained the urge to neutralize this thought. We sought to replicate and extend these findings with measures of behavioral and mental neutralizing. Additionally, we investigated possible mechanisms that might be involved in the effects of rumination on the UIT. We activated a UIT by asking students ( N = 105) to write down a sentence stating that they wished a loved person would die in a car accident. Participants were randomly allocated to rumination about the UIT, rumination about negative mood, or distraction. As predicted, rumination about the UIT maintained the urge to neutralize the UIT, relative to rumination about negative mood and distraction. In addition, rumination about the UIT also maintained distress associated with the UIT compared to rumination about negative mood and distraction. The effects of rumination did not extend to behavioral or mental neutralizing. UIT frequency and vividness were unaffected by rumination. The present findings strengthen the confidence that rumination contributes to the maintenance of UITs.

Postoperative complications related to intraoperative hypothermia

Introducción: La hipotermia es un evento común en el período intraoperatorio, acarrea consecuencias en la recuperación del paciente, con complicaciones en diversos sistemas del organismo, como el cardíaco, respiratorio, tegumentario, digestivo, inmunológico y también el sistema de coagulación.Objetivo: Analizar las complicaciones presentadas por el paciente en el período postoperatorio relacionadas con la hipotermia intraoperatoria.Métodos: Estudio de cohorte retrospectivo, muestra compuesta por 54 registros clínicos de pacientes, participantes de un estudio anterior, de diseño experimental, en que fueron sometidos o no a infusión de solución intravenosa caliente, en el período intraoperatorio y de recuperación anestésica. Las variables fueron analizadas en 4 tiempos diferentes, a la llegada a la Unidad de Internación, después de 17, 32 y 108 horas de período postoperatorio. El modelo utilizado fue el logístico marginal.Resultados: La mayoría de los pacientes 40 (74,07%) eran del sexo femenino, edad media de 47,06 años, y 42 (77,78%) salieron normotérmicos de la Sala de Recuperación Post-Anestésica, con temperatura media de 36,2ºC. En cuanto a la comparación de las variables entre los grupos de pacientes normotérmicos e hipotérmicos, a lo largo del tiempo, las variables que presentaron significancia estadística fueron el tiempo de internación, dolor, náusea y herida operatoria con presencia de secreción, con p-valor menor que 0.05.Conclusión: Ante las complicaciones encontradas en este estudio, se hace necesario el desarrollo de acciones de prevención y control de la hipotermia intraoperatoria buscando una mejor recuperación del paciente en el período de postoperatorio. Introduction: Hypothermia is a common event in the intraoperative period, it triggers consequences in the recovery of the patient, with complications in several systems of the organism, such as cardiac, respiratory, integumentary, digestive, immunological and also the coagulation system.Objective: To analyze the complications presented by the patient in the postoperative period related to intraoperative hypothermia.Methods: A retrospective cohort study was carried out in a sample composed of 54 patients' files, from a previous experimental study, in which they were submitted or not to warmed intraoperative intravenous infusion and anesthetic recovery. The variables were analyzed at 4 different times, upon arrival at the hospitalization unit, after 17, 32 and 108 hours postoperative. The model used was the marginal logistics.Results: The majority of patients 40 (74.07%) were female, mean age of 47.06 years, 42 (77.78%) were normothermic patients from the Post Anesthesia Recovery Room, with a mean temperature of 36.2ºC. Regarding the comparison between variables and groups of normothermic and hypothermic patients, over time, the variables that presented statistical significance were the time of hospitalization, pain, nausea, evacuation and surgical wound with presence of secretion, with a p-value less than 0.05.Conclusion: In view of the complications found in this study, it is necessary to develop preventive and control actions for intraoperative hypothermia aiming at a better recovery of the patient in the postoperative period. Introdução: A hipotermia é um evento comum no período intraoperatório, acarreta consequências na recuperação do paciente, com complicações em diversos sistemas do organismo, como o cardíaco, respiratório, tegumentar, digestório, imunológico e também o sistema de coagulação. Objetivo: Analisar as complicações apresentadas pelo paciente no período de pós-operatório relacionadas com a hipotermia intraoperatória.Métodos: Estudo de coorte retrospectivo, amostra composta por 54 prontuários de pacientes, participantes de um estudo anterior, de delineamento experimental, em que foram submetidos ou não à infusão venosa aquecida no período intraoperatório e de recuperação anestésica. As variáveis foram analisadas em 4 tempos diferentes, na chegada a Unidade de Internação, após 17, 32 e 108 horas de período pós-operatório. O modelo utilizado foi o logístico marginal.Resultados: A maioria dos pacientes 40 (74,07%) eram do sexo feminino, com média de idade de 47,06 anos, e 42 (77,78%) saíram normotérmicos da Sala de Recuperação Pós-Anestésica, com temperatura média de 36,2ºC. Em relação à comparação entre as variáveis e os grupos de pacientes normotérmicos e hipotérmicos, ao longo do tempo, as variáveis que apresentaram significância estatística foram o tempo de internação, dor, náusea, evacuação e aspecto da ferida operatória com presença de secreção, com p-valor menor que 0,05. Conclusão: Diante das complicações encontradas neste estudo, faz-se necessário o desenvolvimento de ações de prevenção e controle da hipotermia intraoperatória visando uma melhor recuperação do paciente no período de pós-operatório.