Clogging and Unclogging of Hydrocarbon-Contaminated Nanochannels.

The recent advantages of the fabrication of artificial nanochannels enabled new research on the molecular transport, permeance, and selectivity of various gases and molecules. However, the physisorption/chemisorption of the unwanted molecules (usually hydrocarbons) inside nanochannels results in the alteration of the functionality of the nanochannels. We investigated contamination due to hydrocarbon molecules, nanochannels made of graphene, hexagonal boron nitride, BC2N, and molybdenum disulfide using molecular dynamics simulations. We found that for a certain size of nanochannel (i.e., h = 0.7 nm), as a result of the anomalous hydrophilic nature of nanochannels made of graphene, the hydrocarbons are fully adsorbed in the nanochannel, giving rise to full uptake. An increasing temperature plays an important role in unclogging, while pressure does not have a significant role. The results of our pioneering work contribute to a better understanding and highlight the important factors in alleviating the contamination and unclogging of nanochannels, which are in good agreement with the results of recent experiments.

A Volumetric Metric for Monitoring Intracranial Aneurysms: Repeatability and Growth Criteria in a Longitudinal MR Imaging Study.

BACKGROUND AND PURPOSE: The reliability of contrast-enhanced MRA in monitoring serial volumetric changes of unruptured intracranial aneurysms has not been established. We aimed to determine the coefficient of variance of contrast-enhanced MRA in measuring aneurysm volumes, thus establishing criteria for aneurysm growth and permitting identification of variables predictive of growth. MATERIALS AND METHODS: Aneurysm volumes were measured from serial contrast-enhanced MRA studies of patients with untreated intracranial aneurysms who underwent >2 sequential MR imaging evaluations. After coregistering all sequential studies in 3D space for each aneurysm and signal intensity normalization, aneurysm volume was determined across all time points. A linear mixed effects model was built to estimate the coefficient of variance of the measurement as well as to determine predictive variables. Growth was defined as relative growth exceeding 2 times the measurement coefficient of variance (sudden growth, as 4 times the coefficient of variance). RESULTS: A total of 95 patients with 112 aneurysms were included (5.9 scans during 4.0 years on average, 616 scan measurements in total). The coefficient of variance was 5.5% of the aneurysm volume, and the relative growth rate was dependent on the location: anterior cerebral artery, 4.52% per year; vertebral artery, 2.46% per year; middle cerebral artery, 2.74% per year; basilar artery, 2.36% per year; internal carotid artery, 1.14% per year. Thirty-six of 112 (32%) aneurysms were characterized as growing, and 11/36 of them had an episode of sudden growth. CONCLUSIONS: Volume measurement of unruptured intracranial aneurysms by contrast-enhanced MRA seems a reliable metric for tracking the growth trajectory of aneurysms. Furthermore, the aneurysm growth rate differs among different locations.

MR Venous Flow in Sigmoid Sinus Diverticulum.

BACKGROUND AND PURPOSE: Case reports demonstrate that coiling of a sigmoid sinus diverticulum can treat pulsatile tinnitus. We hypothesized that MR imaging 4D flow and computational fluid dynamics would reveal distinct blood flow patterns in the venous outflow tract in these patients. MATERIALS AND METHODS: Patients with pulsatile tinnitus of suspected venous etiology underwent MR imaging at 3T, using venous phase contrast-enhanced MR angiography, 4D flow, and 2D phase contrast. The contrast-enhanced MRA contours were evaluated to determine the presence and extent of a sigmoid sinus diverticulum. Computational fluid dynamics analysis was performed using the 4D flow inlet flow and the luminal contours from contrast-enhanced MRA as boundary conditions. In addition, computational fluid dynamics was performed for the expected post treatment conditions by smoothing the venous geometry to exclude the sigmoid sinus diverticulum from the anatomic boundary conditions. Streamlines were generated from the 4D flow and computational fluid dynamics velocity maps, and flow patterns were examined for the presence of rotational components. RESULTS: Twenty-five patients with pulsatile tinnitus of suspected venous etiology and 10 control subjects were enrolled. Five (20%) of the symptomatic subjects had sigmoid sinus diverticula, all associated with an upstream stenosis. In each of these patients, but none of the controls, a stenosis-related flow jet was directed toward the opening of the sigmoid sinus diverticulum with rotational flow patterns in the sigmoid sinus diverticulum and parent sigmoid sinus on both 4D flow and computational fluid dynamics. CONCLUSIONS: Consistent patterns of blood flow can be visualized in a sigmoid sinus diverticulum and the parent sinus using 4D flow and computational fluid dynamics. Strong components of rotational blood flow were seen in subjects with sigmoid sinus diverticula that were absent in controls.

A comparative study of nutritional status and foodstuffs in adolescent girls in iran.

BACKGROUND: The prevalence of obesity and overweight in children and adolescents is increasing world-wide. Obesity in children and adolescents is a major risk factor for diabetes, heart diseases, hypertension, and cancer in adulthood. AIM: The aim of the study was to compare the nutritional status and food-stuffs among high-school girls in Arak, Iran, in matter of body mass index (BMI) and associated factors. SUBJECTS AND METHODS: A cross-sectional survey of a representative sample of 278 adolescents was conducted in six randomly chosen high-schools. Height and weight of students were collected using standard methods and the BMI calculated and BMI percentiles of these girls are compared with the Center of Disease Control and Prevention (CDC) reference data. The 5(th), 8(th), and 95(th) percentiles of the CDC were adopted as cut-off points for underweight, overweight and obese girls, respectively. Data were analyzed using SPSS by analysis of variance and Chi-square tests. RESULTS: On the basis of CDC, the overall prevalence rates of underweight, overweight, and obesity were estimated 10.1% (28/278), 12.9% (36/278), and 1.4% (4/278), respectively. There was no significant difference between nutritional knowledge scores and the rate of physical activities in various groups. The mean age at menarche was significantly higher among the obese girls (P = 0.02). Consumption of ice-cream and chocolate was significantly higher in the obese girls group (P = 0.03). CONCLUSION: According to the present study, the prevalence of overweight and obesity in high-school girls of Arak is lower than that of many other parts of Iran and some neighboring countries, which are at the high-risk of overweight and obesity. This study warrants the necessity of paying attention to promote healthy life-style and weight control. The earlier age of menarche is alarming.

Video game training enhances cognitive control in older adults.

Cognitive control is defined by a set of neural processes that allow us to interact with our complex environment in a goal-directed manner. Humans regularly challenge these control processes when attempting to simultaneously accomplish multiple goals (multitasking), generating interference as the result of fundamental information processing limitations. It is clear that multitasking behaviour has become ubiquitous in today's technologically dense world, and substantial evidence has accrued regarding multitasking difficulties and cognitive control deficits in our ageing population. Here we show that multitasking performance, as assessed with a custom-designed three-dimensional video game (NeuroRacer), exhibits a linear age-related decline from 20 to 79 years of age. By playing an adaptive version of NeuroRacer in multitasking training mode, older adults (60 to 85 years old) reduced multitasking costs compared to both an active control group and a no-contact control group, attaining levels beyond those achieved by untrained 20-year-old participants, with gains persisting for 6 months. Furthermore, age-related deficits in neural signatures of cognitive control, as measured with electroencephalography, were remediated by multitasking training (enhanced midline frontal theta power and frontal-posterior theta coherence). Critically, this training resulted in performance benefits that extended to untrained cognitive control abilities (enhanced sustained attention and working memory), with an increase in midline frontal theta power predicting the training-induced boost in sustained attention and preservation of multitasking improvement 6 months later. These findings highlight the robust plasticity of the prefrontal cognitive control system in the ageing brain, and provide the first evidence, to our knowledge, of how a custom-designed video game can be used to assess cognitive abilities across the lifespan, evaluate underlying neural mechanisms, and serve as a powerful tool for cognitive enhancement.

Alterations in osmotic fragility of the red blood cells in hypo- and hyperthyroid patients.

BACKGROUND: Changes in concentration of thyroid hormones can affect Na+-K+-ATPase number and activity and phospholipid composition of the cell membranes leading to changes in the surface to volume ratio and strength of membrane. AIM: In this study, the osmotic fragility of the red blood cells from non-treated hypo- and hyperthyroid patients was compared to that of control subjects. MATERIAL/SUBJECTS AND METHODS: After 3 washings with normal saline, red blood cells were placed in varying concentrations of sodium chloride (Na- Cl) (0-0.9%) and fragility was assessed with colorimetric method; to do this, after the incubation period, tubes were centrifuged and the optical density of the tubes was measured. Hemolysis percentage in tubes was calculated based on 100% hemolysis in the tubes containing no NaCl (0%). RESULTS: Osmotic fragility of the cells from hyperthyroid patients in 0.45% NaCl was significantly lower than control subjects (74.6%+/-30.2 vs 93.8%+/-9.1, p<0.01). The osmotic fragility of red blood cells in 0.5% concentration of sodium chloride in hyperthyroid patients was significantly lower compared to that of controls (27.8%+/-26.0 vs 63.5%+/-27.5, p<0.001). No significant difference was observed between the osmotic fragility of the hypothyroid patients compared with control subjects. CONCLUSIONS: Alteration in osmotic fragility is seen in patients with hyperthyroidism; however, anemia reported in hypo- or hyperthyroid patients is not due to high osmotic fragility of red blood cells and other causes need to be investigated.

Predatory mites avoid ovipositing near counterattacking prey.

Attacking prey is not without risk; predators may endure counterattack by the prey. Here, we study the oviposition behaviour of a predatory mite (Iphiseius degenerans) in relation to its prey, the western flower thrips (Frankliniella occidentalis). This thrips is capable of killing the eggs of the predator. Thrips and predatory mites - apart from feeding on each other - can also feed and reproduce on a diet of pollen. Because thrips may aggregate at pollen patches, such patches may be risky for oviposition by the predatory mites. We found that, in absence of thrips, predatory mites lay their eggs close to pollen, but further away when thrips are present. Predatory mite eggs near pollen were killed more frequently by thrips than when they were deposited further away. The oviposition behaviour of the predatory mite was also studied in absence of thrips, but in presence of the alarm pheromone of thrips. This pheromone is normally secreted upon contact with predators or competitors. When applied close to the pollen. predatory mites oviposited significantly further away from it. When the alarm pheromone was applied away from the food source, most eggs were found near the pollen. These results indicate that female predatory mites show flexible oviposition behaviour in response to the presence of their counterattacking prey.