Multiscale modeling of unfolding and bond dissociation of rubredoxin metalloprotein.

Mechanical properties of proteins that have a crucial effect on their operation. This study used a molecular dynamics simulation package to investigate rubredoxin unfolding on the atomic scale. Different simulation techniques were applied, and due to the dissociation of covalent/hydrogen bonds, this protein demonstrates several intermediate states in force-extension behavior. A conceptual model based on the cohesive finite element method was developed to consider the intermediate damages that occur during unfolding. This model is based on force-displacement curves derived from molecular dynamics results. The proposed conceptual model is designed to accurately identify bond rupture points and determine the associated forces. This is achieved by conducting a thorough comparison between molecular dynamics and cohesive finite element results. The utilization of a viscoelastic cohesive zone model allows for the consideration of loading rate effects. This rate-dependent model can be further developed and integrated into the multiscale modeling of large assemblies of metalloproteins, providing a comprehensive understanding of mechanical behavior while maintaining a reduced computational cost.

Configuration and Optimization of a Minichannel Using Water-Alumina Nanofluid by Non-Dominated Sorting Genetic Algorithm and Response Surface Method.

Nanofluids in minichannels with various configurations are applied as cooling and heating fluids. Therefore, it is essential to have an optimal design of minichannels. For this purpose, a square channel with a cylinder in the center connected to wavy fins at various concentrations of an Al2O3 nanofluid is simulated using the finite volume method (FVM). Moreover, central composite design (CCD) is used as a method of design of experiment (DOE) to study the effects of three input variables, namely the cylinder diameter, channel width, and fin radius on the convective heat transfer and pumping power. The impacts of the linear term, together with those of the square and interactive on the response variables are determined using Pareto and main effects plots by an ANOVA. The non-dominated sorting genetic algorithm-II (NSGA-II), along with the response surface methodology (RSM) is applied to achieve the optimal configuration and nanofluid concentration. The results indicate that the effect of the channel width and cylinder diameter enhances about 21% and 18% by increasing the concentration from 0% to 5%. On the other hand, the pumping power response is not sensitive to the nanofluid concentration. Besides, the channel width has the highest and lowest effect on the heat transfer coefficient (HTC) and pumping power, respectively. The optimization for a concentration of 3% indicates that in Re = 500 when the geometry is optimized, the HTC enhances by almost 9%, while the pumping power increases by about 18%. In contrast, by increasing the concentration from 1% to 3%, merely an 8% enhancement in HTC is obtained, while the pumping power intensifies around 60%.

Lobectomy in traumatic brain injury patients with intracerebral hemorrhage and delayed contusion.

BACKGROUND: TBI, standing for Traumatic Brain Injury, is a leading cause of death worldwide; nonetheless, data on its management has hitherto been sparse. In view of the fact that brain lobectomy is a contentious issue in the management of TBI, we set out the current study to assess the mortality rate and outcomes of TBI with delayed contusion or Intracerebral Hemorrhage (ICH) undergoing lobectomy. METHODS: We evaluated 135 TBI patients with delayed contusion or ICH undergoing brain lobectomy from 2001 to 2013. Withal, the mortality and Glasgow Outcome Scale (GOS) and Glasgow Comma Scale (GCS) rates were assessed in these patients and the association in between was sought. RESULTS: The TBI patients undergoing brain lobectomy (77% male versus 23 % female) had a mean age of 43.4±20.3 years and experienced a survival rate of 62.2% (71% in females versus 60% in males). Favorable GOS was observed in 53% of male patients, compared with 27% in the females. Age was demonstrated to significantly affect the mortality rate (p=0.0001). Initial GCS score was associated with GOS as 79.1% of the survived patients with a GCS of higher than 9 on admission were discharged with favorable GOS. CONCLUSIONS: The evidence from the present study indicates that lobectomy can be an acceptable surgical procedure in management of TBI patients with delayed contusion or ICH.

Modeling and analysis of biomagnetic blood Carreau fluid flow through a stenosis artery with magnetic heat transfer: A transient study.

We present a numerical investigation of tapered arteries that addresses the transient simulation of non-Newtonian bio-magnetic fluid dynamics (BFD) of blood through a stenosis artery in the presence of a transverse magnetic field. The current model is consistent with ferro-hydrodynamic (FHD) and magneto-hydrodynamic (MHD) principles. In the present work, blood in small arteries is analyzed using the Carreau-Yasuda model. The arterial wall is assumed to be fixed with cosine geometry for the stenosis. A parametric study was conducted to reveal the effects of the stenosis intensity and the Hartman number on a wide range of flow parameters, such as the flow velocity, temperature, and wall shear stress. Current findings are in a good agreement with recent findings in previous research studies. The results show that wall temperature control can keep the blood in its ideal blood temperature range (below 40°C) and that a severe pressure drop occurs for blockages of more than 60 percent. Additionally, with an increase in the Ha number, a velocity drop in the blood vessel is experienced.

The role of early posttraumatic neuropsychological outcomes in the appearance of latter psychiatric disorders in adults with brain trauma.

BACKGROUND: The objective was to determine the predictors of posttraumatic psychiatric disorders (PTPD) during the first 6 months following traumatic brain injury (TBI) focusing on neuroimaging, clinical and neuropsychological appraisements during acute and discharge phase of TBI. MATERIALS AND METHODS: We designed a prospective, longitudinal study in which 150 eligible TBI patients were entered. Postresuscitation brain injury severity and discharged functional outcome were evaluated by standard clinical scales. First neuroimaging was done at a maximum of 24 h after head trauma. Early posttraumatic (PT) neuropsychological outcomes were assessed using Persian neuropsychological tasks at discharge. The standardized psychiatric assessments were carefully implemented 6 months postinjury. A total of 133 patients returned for follow-up assessment at 6 months. They were divided into two groups according to the presence of PTPD. RESULTS: Apparently, aggression was the most prevalent type of PTPD (31.48%). There was no significant difference between groups regarding functional outcome at discharge. Diffuse axonal injury (12.96%) and hemorrhages (40.74%) within the cortex (42.59%) and sub-cortex (33.33) significantly occurred more prevalent in PTPD group than non-PTPD ones. Primary postresuscitation TBI severity, early PT lingual deficit and subcortical lesion on first scan were able to predict PTPD at 6 months follow-up. CONCLUSION: Almost certainly, the expansive dissociation risk of cortical and subcortical pathways related to linguistic deficits due to severe intracranial lesions over a period of time can augment possibility of subsequent conscious cognitive-emotional processing deficit, which probably contributes to latter PTPD. Hence, early combined therapeutic supplies including neuroprotective pharmacotherapy and neurofeedback for neural function reorganization can dampen the lesion expansion and latter PTPD.

Basic effects of pulp refining on fiber properties--a review.

The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented.

A comprehensive review of milk fouling on heated surfaces.

Heat exchanger performance degrades rapidly during operation due to formation of deposits on heat transfer surfaces which ultimately reduces service life of the equipment. Due to scaling, product deteriorates which causes lack of proper heating. Chemistry of milk scaling is qualitatively understood and the mathematical models for fouling at low temperatures have been produced but the behavior of systems at ultra high temperature processing has to be studied further to understand in depth. In diversified field, the effect of whey protein fouling along with pressure drop in heat exchangers were conducted by many researchers. Adding additives, treatment of heat exchanger surfaces and changing of heat exchanger configurations are notable areas of investigation in milk fouling. The present review highlighted information about previous work on fouling, influencing parameters of fouling and its mitigation approach and ends up with recommendations for retardation of milk fouling and necessary measures to perform the task.

Numerical investigation of heat transfer enhancement in a rectangular heated pipe for turbulent nanofluid.

Thermal characteristics of turbulent nanofluid flow in a rectangular pipe have been investigated numerically. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated. Four different types of nanoparticles Al2O3, ZnO, CuO, and SiO2 at different volume fractions of nanofluids in the range of 1% to 5% are considered in the present investigation. In this paper, effect of different Reynolds numbers in the range of 5000 < Re < 25000 on heat transfer characteristics of nanofluids flowing through the channel is investigated. The numerical results indicate that SiO2-water has the highest Nusselt number compared to other nanofluids while it has the lowest heat transfer coefficient due to low thermal conductivity. The Nusselt number increases with the increase of the Reynolds number and the volume fraction of nanoparticles. The results of simulation show a good agreement with the existing experimental correlations.