Larger Cross-sectional Area Research Articles

Computation of magnetization, exchange stiffness, anisotropy, and susceptibilities in large-scale systems using GPU-accelerated atomistic parallel Monte Carlo algorithms

Monte Carlo algorithms are frequently used in atomistic simulations, including for computation of magnetic parameter temperature dependences in multiscale simulations. Even though parallelization strategies for Monte Carlo simulations of lattice spin models are known, its application to computation of magnetic parameter temperature dependences is lacking in the literature. Here we show how, not only the unconstrained algorithm, but also the constrained atomistic Monte Carlo algorithm, can be parallelized for any spin–lattice crystal structure. Compared to the serial algorithms, the parallel Monte Carlo algorithms are typically over 200 times faster, allowing computations in systems with over 10 million atomistic spins on a single graphical processing unit with relative ease. Implementation and testing of the algorithms was carried out in large-scale systems, where finite-size effects are reduced, by accurately computing temperature dependences of magnetization, uniaxial and cubic anisotropies, exchange stiffness, and susceptibilities. In particular for the exchange stiffness the Bloch domain wall method was used with a large cross-sectional area, which allows accurate computation of the domain wall width up to the Curie temperature. The exchange stiffness for a simple cubic lattice closely follows an mk scaling at low temperatures, with k < 2 dependent on the anisotropy strength. However, close to the Curie temperature the scaling exponent tends to k = 2. Furthermore, the implemented algorithms are applied to the computation of magnetization temperature dependence in granular thin films with over 15 million spins, as a function of average grain size and film thickness. We show the average Curie temperature in such systems may be obtained from a weighted Bloch series fit, which is useful for analysis of experimental results in granular thin films.

Evaluating bony predictors of bite force across the order Carnivora.

In carnivorans, bite force is a critical and ecologically informative variable that has been correlated with multiple morphological, behavioral, and environmental attributes. Whereas in vivo measures of biting performance are difficult to obtain in many taxa-and impossible in extinct species-numerous osteological proxies exist for estimating masticatory muscle size and force. These proxies include both volumetric approximations of muscle dimensions and direct measurements of muscular attachment sites. In this study, we compare three cranial osteological techniques for estimating muscle size (including 2D-photographic and 3D-surface data approaches) against dissection-derived muscle weights and physiological cross-sectional area (PCSA) within the jaw adductor musculature of 40 carnivoran taxa spanning eight families, four orders of magnitude in body size, and the full dietary spectrum of the order. Our results indicate that 3D-approaches provide more accurate estimates of muscle size than do surfaces measured from 2D-lateral photographs. However, estimates of a muscle's maximum cross-sectional area are more closely correlated with muscle mass and PCSA than any estimates derived from muscle attachment areas. These findings highlight the importance of accounting for muscle thickness in osteological estimations of the masticatory musculature; as muscles become volumetrically larger, their larger cross-sectional area does not appear to be associated with a proportional increase in the attachment site area. Though volumetric approaches approximate muscle dimensions well across the order as a whole, caution should be exercised when applying any single method as a predictor across diverse phylogenies.

Incorporation of Molecular Reorientation into Modeling Surface Pressure-Area Isotherms of Langmuir Monolayers.

Langmuir monolayers can be assembled from molecules that change from a low-energy orientation occupying a large cross-sectional area to a high-energy orientation of small cross-sectional area as the lateral pressure grows. Examples include cyclosporin A, amphotericin B, nystatin, certain alpha-helical peptides, cholesterol oxydation products, dumbbell-shaped amphiphiles, organic–inorganic nanoparticles and hybrid molecular films. The transition between the two orientations leads to a shoulder in the surface pressure-area isotherm. We propose a theoretical model that describes the shoulder and can be used to extract the energy cost per molecule for the reorientation. Our two-state model is based on a lattice–sublattice approximation that hosts the two orientations and a corresponding free energy expression which we minimize with respect to the orientational distribution. Inter-molecular interactions other than steric repulsion are ignored. We provide an analysis of the model, including an analytic solution for one specific lateral pressure near a point of inflection in the surface pressure-area isotherm, and an approximate solution for the entire range of the lateral pressures. We also use our model to estimate energy costs associated with orientational transitions from previously reported experimental surface pressure-area isotherms.

Strengthening of Edge and Corner Columns using Concrete Jackets

Strengthening of columns using concrete jackets depends on friction at the interface between them. So strengthening of edge and corner columns in only one story needs a large cross section area due to the shortage of friction length which leads to architectural issues. This research aims to study strengthening the edge and corner columns using a concrete Jacket in more than one story which increases the friction area between the Jacket and the original column. As a result, the load transferred from original column to the jacket will be increased. Thirteen models were done using ANSYS program to study the effect of various factors on the Jacket capacity such as the number of strengthened floors, the Jacket type (two sides or three sides), and whether there were shear connectors or not. The results showed that in the case of the edge and corner columns, it is preferable to strengthen the column by making a concrete Jacket on at least two or three floors to increase the surface area, which leads to increase the friction and thus increases the capacity of the strengthened column by an acceptable percentage. The results of ANSYS models were compared with the Indian code IS 15988 (2013) and the results were shown differently because the code equations depend on the presence of a full bond between the concrete column and the Jacket, which does not occur, but rather the load is transferred by friction between the Jacket and the original column. Doi: 10.28991/cej-2021-03091716 Full Text: PDF

Supercooling in a new two-stage thermoelectric cooler design with phase change material and Thomson effect

A novel physical model of a two-stage thermoelectric cooler (TEC) is developed, based on geometry factor (γ) analysis between stages under pulsed current conditions and with phase change material (PCM), to improve performance. A detailed investigation of a two-stage Peltier cooler based on a general thermodynamic formulation considering the Thomson effect is presented. The minimum cold side temperature, coefficient of performance (COP), and further the thermoelement’s characteristic temperature profiles are discussed. The numerical analysis was carried out considering square pulse current, hot side heat transfer, metal strips, ceramic plates, and a PCM material volume in the heat sink. The investigation results proved that the geometry relation between both stages and the Thomson effect directly impacts supercooling, and a higher reduction in the cold side temperature can be achieved compared with conventional thermoelectric coolers. A reduction of 25.2 K in a two-stage over a single-stage TEC with PCM is achieved considering a large cross-sectional area in the first stage. It has been found that the holding time and the characteristic temperature profiles during and after pulse operation depends strongly on Thomson heat and geometry. A shorter holding time and maximum temperature drop are found for γ>1 values due to the PCM’s melting temperature and the higher pulse current. The characteristic cooling length reveals the part of the semiconductor element that is cooled during pulse operation. Results will guide the design or selection of a heat sink crucial to a solid-state cooling device’s overall performance.

A large beam high efficiency radio frequency neutron spin flipper.

A design for a radio frequency (RF) neutron spin flipper obtained from magneto-static and neutron spin transport simulations is presented. The RF flipper constructed from this design provides a flipping probability of 0.999 or better for a beam size 6cm wide and 15cm high and a wavelength band between 0.4 and 0.6nm. Three permanent magnet guide field sections with air gaps provide a linear field gradient along the beam propagation direction over a large cross-sectional area. An RF oscillator based on coupling the resonant coil of a Hartley oscillator to the excitation coil was developed, which provides a higher current and, thereby, a larger RF amplitude, as compared to a conventional RF power amplifier. Two opaque He3 neutron spin filters were employed to measure the flipping probability of the flipper with very high precision. A spatially uniform flipping probability of 0.9995(2) or higher was measured over the large cross-sectional area neutron guide. This RF neutron spin flipper will be employed in a polychromatic beam reflectometer at the National Institute of Standards and Technology Center for Neutron Research. This design can be applied to other polarized neutron instruments or applications requiring a very high continuous flipping probability of the neutron spin for a large cross-sectional area beam.

Effect of Abrupt Changes in the Cross-Sectional Area of a Pipe on Flame Propagation Characteristics of CH4/Air Mixtures.

To study the flame propagation characteristics of methane/air premixed gas in the pipeline with a sudden change of the pipe cross-sectional area, six kinds of customized pipes are used to study the methane/air premixed gas with a concentration of 9.5%. The results show that when the initial smooth flame front encounters an abrupt change in the cross-sectional area, the flame front becomes disordered and a turbulent flame is formed. A greater change in the cross-sectional area results in more severe flame turbulence. Compared with larger cross-section pipes set at the ignition end and downstream end, when the large cross-sectional area pipe is set in the middle of the pipe, the flame propagation process receives the secondary mutation induction effect of the abrupt cross section and the turbulence effect is stronger. The maximum propagation velocity and pressure are observed in configuration with the larger pipe in the middle of the pipe network. Moreover, when the cross-sectional area of this larger pipe increases, the flame is more substantially influenced by longitudinal expansion, the maximum propagation velocity and maximum overpressure increase accordingly, and the pressure oscillations are more obvious.

Upsizing high-strength fail-safe steel through warm tempforming

Fail-safe (FS) steel is designed with enhanced fracture toughness through the crack deflection mechanism in an anisotropic microstructure. In this study, commercial boron (B)-bearing medium-carbon low-alloy steel bars with a cross-sectional area of 1390 mm2 were water-quenched and tempered at temperatures between 400 °C and 500 °C, followed by multi-pass caliber-rolling (i.e., warm tempforming). Tensile, Charpy V-notch (CVN) impact, and hydrogen embrittlement (HE) properties of the warm tempformed samples were investigated and compared with the rolling reductions of 45–92% to optimize the rolling conditions for upsizing the FS steel. Warm tempforming at 400 °C with a rolling reduction of 66% successfully produced an FS steel bar with a large cross-sectional area of 470 mm2. The evolution of a heterogeneous and anisotropic ultrafine-grained structure through the warm deformation of tempered martensite and pearlite generated an excellent combination of CVN toughness and HE resistance at the ultimate tensile strength of 1400 MPa. Delayed fracture resistance of the FS steels was also evaluated to be far superior to those of conventionally quenched and tempered steels, based on the balance between the HE susceptibility and hydrogen entry. Furthermore, it was observed that excessive warm tempforming to a rolling reduction of 92% tended to degrade the tensile elongation and HE resistance. The mechanism of the variations in mechanical properties during warm tempforming is discussed in association with the microstructural evolution.

Multi-center, single arm phase II study of the dual mTORC1/mTORC2 inhibitor vistusertib for patients with recurrent or progressive grade II-III meningiomas.

2024 Background: Grade II/III meningiomas represent about 20% of tumors and have increased rates of recurrence with no approved medical therapies. Historically, the progression-free survival at 6 months (PFS-6) for these tumors is 25%. The Response Assessment in Neuro-Oncology (RANO) group identified a PFS-6 rate of &gt; 35% to be of interest for trials of grade II/III meningioma. Methods : NF2 gene inactivation occurs in the majority of meningiomas and is associated with mTORC1 activation. Human studies of everolimus for neurofibromatosis 2 patients documented growth arrest in only a minority of tumors. Based on our studies showing mTORC2/SGK1 pathway activation in NF2-deficient meningiomas and the known paradoxical activation of the mTORC2/AKT pathway in meningiomas, we hypothesized that dual inhibition of mTORC1/2 would be superior in meningiomas. Treatment of primary meningioma cells with vistusertib led to decreased cell proliferation and showed greater efficacy than rapamycin, regardless of NF2 expression. We studied the effect of vistusertib in patients with progressive or recurrent grade II/III meningiomas (NCT03071874). Vistusertib was administered orally at 125mg twice daily on two consecutive days each week. MRIs were obtained every 2 cycles (1 cycle = 28 days). Tumor size was defined as the largest cross-sectional area. Progression was defined as ≥25% increase in the sum of products of all measurable lesions over smallest sum observed. The primary endpoint was PFS-6. Secondary endpoints included toxicity, radiographic response, and correlative studies including immunohistochemistry for mTORC1/2 pathway activation and genetic biomarkers. Results: Twenty-eight patients (13 female), with a median age of 58 years (range, 32 to 77 years), were enrolled in this multicenter study. The median Karnofsky performance status was 80. Twenty-five patients have been followed to six months or to tumor progression. The median duration of treatment was 6.5 month (range, 1-18 months). Four patients chose to discontinue treatment, 1 withdrew to intercurrent illness, and 1 was withdrawn due to non-compliance. PFS-6 is 51.5% (CI, 29.3% - 70.0%). Adverse events at least possibly related to vistusertib with frequency &gt; 10% include nausea (54%); fatigue (36%); hypophosphatemia (29%); diarrhea, anorexia, dry mouth, and hypertriglyceridemia (all 14%); hypertension, vomiting, increased ALT, constipation, and weight loss (all 11%). Conclusions: Vistusertib treatment was associated with a PFS-6 rate that exceeds the RANO target of 35% for recurrent high-grade meningioma. The follow-up data continue to mature. Adverse events were tolerable in this patient population. Correlative studies to identify biological factors that correlate with response are under way. These data support the initiation of larger randomized studies of vistusertib in this setting. Clinical trial information: NCT03071874.

Відносний рух космічного апарата з аеродинамічним компенсатором у перпендикулярному до площини орбіти напрямку при безконтактному видаленні космічного сміття

The article investigates the feasibility of using an aerodynamic compensator for contactless removal of space debris from low Earth orbits, taking into account aerodynamic disturbances in the direction perpendicular to the orbital plane. The object of the research is a modified scheme of the “ion beam shepherd” de-orbiting concept. The modification consists in replacing an additional electric thruster with an aerodynamic compensator designed to compensate the shepherd spacecraft motion caused by the reaction force of the main electric thruster, the ion plume of which creates a “braking” effect on the space debris object. The shepherd spacecraft with the aerodynamic compensator has a relatively large cross-sectional area. In this case, it is necessary to control the relative motion caused by the aerodynamic disturbances in the direction perpendicular to the orbital plane. This control requires additional propellant for the thrusters of the relative motion control system of the shepherd spacecraft. The article presents the calculation of the propellant consumption using a number of simplifying assumptions. The validity of these assumptions is verified by numerical integration of the equations of relative motion. The feasibility of using the aerodynamic compensator for contactless removal of space debris, taking into account aerodynamic disturbances acting in the direction perpendicular to the orbital plane, is shown.

Design of a Short-Beam Linear Traveling-Wave Piezoelectric Motor.

A straight short-beam linear piezoelectric motor constructed with two sets of ceramic actuators separated with the 1/4 wavelength interval is designed in this article. The piezoelectric ceramic actuators are fabricated in the whole body, which is driven by a two-phase circuit with the same amplitude but a phase difference of π /4. Traveling wave (TW) is formed by superimposing standing waves generated by each set of ceramic actuators. At the ends of the short beam, a wave-reduction mechanism with larger cross-sectional area is designed so that wave reflection is effectively diminished to preserve the TW. The currently developed short-beam linear piezoelectric motor is estimated, which can produce an ideal output speed of 169 mm/s while applying voltage of Vpp = 300 V at 45.49 kHz. Instead of operating as a stator to drive a carriage for example, the short-beam linear piezoelectric motor is implemented on a guide slider, and therefore, a linear piezoelectric motor stage is built. While driving the linear stage employed with a preload 300 GW and a friction coefficient of about 0.15, the propulsion force is measured about 4.8 N, the speed is about 56 mm/s, and the position resolution can achieve in the submicrometer scale.

Comparison of performance of single- and double-core prefabricated vertical drains for thick reclaimed ground improvement

The performance of a double-core prefabricated vertical drain (PVD), which could reduce the well resistance via its large cross-sectional area and structural stability, was investigated experimentally and numerically. The double-core and the conventional single-core PVD, which has been widely adopted in reclaimed ground improvement, were compared in this study. In the experimental investigation, modified Delft tests and a calibration chamber test were carried out in a laboratory to determine the discharge capacities of the PVDs. Thereafter, single- and double-core PVDs were installed in the Busan New Port site, which had a 40 m thickness of clay deposit, and the performances of the PVDs estimated through surface settlements were compared. In addition, a numerical program named ILLICON was applied with field measurements, and a parametric study was conducted for different discharge capacities of the PVDs. The result of the laboratory tests and field measurements indicated that there was no difference in the performance between the two types of PVDs for improving the soft ground, considering actual ground conditions. Similarly, the parametric study results also implied that both PVDs could be satisfactorily applied in thick reclaimed ground, and there is no significant difference in the performance of single- and double-core PVDs.

Higher Hand Grip Strength Is Associated With Greater Radius Bone Size and Strength in Older Men and Women: The Framingham Osteoporosis Study.

ABSTRACTMechanical loading by muscles elicits anabolic responses from bone, thus age‐related declines in muscle strength may contribute to bone fragility in older adults. We used high‐resolution peripheral quantitative computed tomography (HR‐pQCT) to determine the association between grip strength and distal radius bone density, size, morphology, and microarchitecture, as well as bone strength estimated by micro–finite element analysis (μFEA), among older men and women. Participants included 508 men and 651 women participating in the Framingham Offspring Study with grip strength measured in 2011–2014 and HR‐pQCT scanning in 2012–2015. Separately for men and women, analysis of covariance was used to compare HR‐pQCT measures among grip strength quartiles and to test for linear trends, adjusting for age, height, weight, smoking, and physical activity. Mean age was 70 years (range, 50–95 years), and men had higher mean grip strength than the women (37 kg vs. 21 kg). Bone strength estimated by μFEA‐calculated failure load was higher with greater grip strength in both men (p < 0.01) and women (p = 0.04). Higher grip strength was associated with larger cross‐sectional area in both men and women (p < 0.01), with differences in area of 6% and 11% between the lowest to highest grip strength quartiles in men and women, respectively. Cortical thickness was positively associated with grip strength among men only (p = 0.03). Grip strength was not associated with volumetric BMD (vBMD) in men. Conversely, there was a trend for lower total vBMD with higher grip strength among women (p = 0.02), though pairwise comparisons did not reveal any statistically significant differences in total vBMD among grip strength quartiles. Bone microarchitecture (cortical porosity, trabecular thickness, trabecular number) was not associated with grip strength in either men or women. Our findings suggest that the positive association between hand grip strength and distal radius bone strength may be driven primarily by bone size. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Dominant and nondominant distal radius microstructure: Predictors of asymmetry and effects of a unilateral mechanical loading intervention

Most information about distal radius microstructure is based on the non-dominant forearm, with little known about the factors that contribute to bilateral asymmetries in the general population, or what factors may influence bilateral changes over time. Here, we analyzed bilateral high resolution peripheral quantitative computed tomography (HRpQCT) data collected over a 12-month period as part of a clinical trial that prescribed a well-controlled, compressive loading task to the nondominant forearm. Baseline data from 102 women age 21–40, and longitudinal data from 66 women who completed the 12-month trial, were examined to determine factors responsible for side-to-side asymmetries in bone structure and change in structure over time. Cross-sectionally, the dominant radius had 2.4%–2.7% larger cross-sectional area, trabecular area, and bone mineral content than the nondominant radius, but no other differences were noted. Those who more strongly favored their dominant arm had significantly more, thinner, closely spaced trabecular struts in their dominant versus nondominant radius. Individuals assigned to a loading intervention had significant bilateral gains in total bone mineral density (2.0% and 1.2% in the nondominant versus dominant sides), and unilateral gains in the nondominant (loaded) cortical area (3.1%), thickness (3.0%), bone mineral density (1.7%) and inner trabecular density (1.3%). Each of these gains were significantly predicted by loading dose, a metric that included bone strain, number of cycles, and strain rate. Within individuals, change was negatively associated with age, meaning that women closer to age 40 experienced less of a gain in bone versus those closer to age 21. We believe that dominant/nondominant asymmetries in bone structure reflect differences in habitual loads during growth and past ability to adapt, while response to loading reflects current individual physiologic capacity to adapt.

Comparative anatomic and morphometric examination of the interosseous muscle, sesamoid ligaments and flexor tendons of the fetlock in South American camelids.

This study presents a comparative morphological and morphometrical examination of the interosseous muscle (IOM), digital flexor tendons and associated structures of all four species of South American Camelids (SACs): Lama (Lama glama), alpaca (Vicugna pacos), guanaco (Lama guanicoe) and vicuna (Vicugna vicugna). Our findings show that the lamoid interosseous muscle and digital flexor tendons are very similar between species and differences, which have been reported previously, are possibly due to diverging examiner interpretation. Lumbricalis muscles were mostly found as single muscles in this study. The definition of the terminal and dorsal branches of the interosseous muscle is critically revised. The analysis of morphometric data indicates that the size of the individual has a substantial influence on the cross-sectional area (CSA) of the examined structures. Metacarpal/metatarsal bone width is a main predictor of CSA, while the factor species only shows significance in specific sample points. For lama and alpaca, no differences in CSA in relation to species as factor were found. The IOM shows the largest CSAs of the three examined structures in all species, which implies an important load-bearing function. Considerable individual variation remains unexplained by the mentioned factors. This lowers the prospect of CSA reaching diagnostic importance in SAC fetlock pathology.

Suppressing Hippo signaling in the stem cell niche promotes skeletal muscle regeneration.

Lack of blood flow to the lower extremities in peripheral arterial disease causes oxygen and nutrient deprivation in ischemic skeletal muscles, leading to functional impairment. Treatment options for muscle regeneration in this scenario are lacking. Here, we selectively targeted the Hippo pathway in myofibers, which provide architectural support for muscle stem cell niches, to facilitate functional muscle recovery in ischemic extremities by promoting angiogenesis, neovascularization, and myogenesis. We knocked down the core Hippo pathway component, Salvador (SAV1), by using an adeno-associated virus 9 (AAV9) vector expressing a miR30-based triple short-hairpin RNA (shRNA), controlled by a muscle-specific promoter. In a mouse hindlimb-ischemia model, AAV9 SAV1 shRNA administration in ischemic muscles induced nuclear localization of the Hippo effector YAP, accelerated perfusion restoration, and increased exercise endurance. Intravascular lectin labeling of the vasculature revealed enhanced angiogenesis. Using 5-ethynyl-2'-deoxyuridine to label replicating cellular DNA in vivo, we found SAV1 knockdown concurrently increased paired box transcription factor Pax7+ muscle satellite cell and CD31+ endothelial cell proliferation in ischemic muscles. To further study Hippo suppression in skeletal muscle regeneration, we used a cardiotoxin-induced muscle damage model in adult (12-15 weeks old) and aged mice (26-month old). Two weeks after delivery of AAV9 SAV1 shRNA into injured muscles, the distribution of regenerative myofibers shifted toward a larger cross-sectional area and increased capillary density compared with mice receiving AAV9 control. Together, these findings suggest our approach may have clinical promise in regenerative therapy for leg ischemia and muscle injury.

Weld Geometry, Mechanical Properties, Microstructure and Chemical Composition of AA6063 in Tungsten Inert Gas Welding with Intermittent Controlled Wire Feeding Method

In this study, AA 6063 aluminum was joined using Tungsten Inert Gas (TIG) welding with a butt joint. The ER-5356 filler metal feeding method is used intermittently to find its effect on weld geometry, mechanical properties, microstructure, and chemical composition. The dimensions of the specimens used in this study were 120 mm × 50 mm, with a thickness of 3 mm. The ratio used is the configuration of the feed time and delay time. The length ratio of wire filler is varied from a ratio of 4 to 6. The top bead width and back bead width decreased by 17.66% and 40.33%, respectively. At a ratio of 6, it has the largest cross-sectional area of 295.37 ± 27.60 mm2. The results show that the general tensile strength was proportional to the ratio, but the difference was not significant, only around ±8 MPa. The microstructure formed in each weld has different characteristics; conversely, grains with a relatively coarse structure have decreased hardness values. The chemical composition test shows that the length ratio of filler metal feed directly correlates with magnesium’s average weight content, where the weight content of magnesium value tends to be homogeneous in all areas of weld metal (WM).

CA2+ Handling in Non-Failing Hypertrophic Cardiomyocytes Subjected to Inotropic Interventions

Impaired force development during ventricular hypertrophy has been associated with structural and functional alterations of Ca2+ handling proteins. Previous findings in whole hearts and multicellular trabeculae from a rat model of right ventricular (RV) hypertrophy showed spontaneous contractile activity and asynchronous Ca2+ release during inotropic interventions. Our aim was to investigate whether these changes occurred at the single cell level. Male Wistar rats were injected with 60 mg kg−1 of monocrotaline (MCT, n=3) or saline as control (CON, n=4). Four weeks post injection, hearts were isolated and enzymatically digested to yield rod-shaped quiescent cardiomyocytes. Aliquots of RV myocytes were collected and measurements of cell shortening and intracellular Ca2+ (fura-2AM, 340/380 ratio) were made in response to inotropic interventions (increased stimulation frequency and ß-adrenergic stimulation). Application of 20mM caffeine revealed Ca2+ content of the sarcoplasmic reticulum (SR). A separate group of cardiomyocytes were fixed and key proteins were labelled with antibodies for subsequent confocal imaging. MCT myocytes had the largest cross-sectional area (4338 ± 292µm2) versus CON (3170 ± 262µm2, P=0.01), although no difference in cell shortening was observed in response to 1 Hz stimulation. MCT myocytes had larger Ca2+ transients at all stimulation frequencies (P= 0.004) and increased spontaneous activity during ß-adrenergic stimulation. No difference between groups was found in Ca2+ store content, although the time constant of caffeine transient decay was prolonged in MCT (17.3 ± 1.5s) versus CON (13.7 ± 0.6s, P=0.05). Although there was no difference in shortening or SR Ca2+ content, there was evidence of changes in Ca2+ handling in MCT myocytes during inotropic stimulation. Furthermore, hypertrophic MCT myocytes exhibited slower trans-sarcolemmal Ca2+ removal during 20mM caffeine, potentially as a result of disorganized T-tubular arrangement and/or reduced Na+/Ca2+ exchanger abundance.

Comparison of the dilatory effect of three strategies on peripheral veins of the upper extremity in adults.

Dilated veins are associated with increased success of peripheral intravenous cannulation, due to their improved visibility and palpability. We compared three strategies to achieve venodilation (tourniquet, electrical stimulation, or a combined strategy) on increase in venous size. A total of 54 volunteers participated in this cross-over observational study with healthy adults, measuring venous cross-sectional area and diameter at six different sites of the upper extremity. Measurements were performed with ultrasound after performing any dilation strategy and compared with non-dilated venous size. An increased cross-sectional area of 25 square millimeters was denoted as clinically relevant, which was detected with paired t-test, Wilcoxon signed rank test, or ANOVA. The cephalic vein was the greatest at all sites (t=12.43, df=39, P<0.001 for the cross-sectional area), but the largest increase in venous size was obtained in the basilic vein (t=12.11, df=39, P<0.001 for the cross-sectional area). The largest increase in venous size was obtained after electrical stimulation followed by tourniquet application at all measurement sites. The basilic vein increased by with 44% in cross-sectional area and 21% in diameter, which were 37% and 17% for the cross-sectional area and diameter of the cephalic vein. In general, the largest sized veins are situated in the upper arm, of which the cephalic vein has the largest cross-sectional area and diameter. The combination of electrical stimulation followed by tourniquet application resulted in the greatest increase in venous size and is therefore considered as the most effective to improve peripheral intravenous cannulation success.

Effects of Air Outlet Position and Air Speed on Airflow and Dust Field Distributions

To meet the actual demands on ventilation and dust removal in mine heading faces and to reduce the potential safety threats and pollution risks of dust, this study investigates the migration and distribution trends of airflow and dust fields at different air outlet positions and air speeds under scenarios using forced ventilation and long-forced-short-exhaust ventilation techniques at the heading face under continuous mining operation, which is accomplished in the engineering context of Xiaobaodang Coal Mine by a combination of two-phase flow analysis and finite element simulation. As the results reveal, the return air speeds exhibit a “rising-falling-stable” trend at different air outlet positions and inlet air speeds. Appropriate increase of inlet air speed is effective in covering the front corner area and in improving the dust distribution in the roadway. Dust concentration on the return air side is markedly higher than on the air duct side, with distribution primarily in the front section. In the case of forced ventilation for the roadway having a large cross-sectional area of 22 m2, reasonable dust distribution on the return air side can be ensured when the air duct outlet is 10 m away from the front and the inlet air speed is 11 m/s. In the case of long-forced-short-exhaust ventilation, reasonable settings are a 15 m distance of air duct outlet from the front and a 9 m/s speed of inlet air.