Cross-sectional Area Distribution Research Articles

Influence of Pore Characteristics on Electrochemical and Biological Behavior of Ti Foams

This study reports on titanium (Ti) foams produced using the powder metallurgy technique. During the investigation, the cross-sectional area and perimeter distributions of the pores within the foam were measured. Metallographic image processing analysis software combined with scanning electron microscopic images demonstrated that the pore size and circularity were affected by varying the volume percentage of the space-holder material. The corrosion resistance was investigated using electrochemical impedance spectroscopy and cyclic polarization tests. MG-63 osteoblast-like cells were used to study the biocompatibility and to evaluate the cell attachment, viability, and alkaline phosphatase activity. Analytical results indicated that 50 and 60 vol.% samples were suitable for biomedical applications. Because of the high degree of interconnectivity in the 60 and 70% porosity samples, the electrochemical parameters produced similar results. The corrosion rate of the porous samples showed that the amount of dissolved Ti was at an acceptable level that can be ejected by the body. Applying a fluoridated hydroxyapatite coating significantly increased the osteoblast cell functions on the porous surface.

Creating normograms of dural sinuses in healthy persons using computer-assisted detection for analysis and comparison of cross-section dural sinuses in the brain

Dural sinuses vary in size and shape in many pathological conditions with abnormal intracranial pressure. Size and shape normograms of dural brain sinuses are not available. The creation of such normograms may enable computer-assisted comparison to pathologic exams and facilitate diagnoses. The purpose of this study was to quantitatively evaluate normal magnetic resonance venography (MRV) studies in order to create normograms of dural sinuses using a computerized algorithm for vessel cross-sectional analysis. This was a retrospective analysis of MRV studies of 30 healthy persons. Data were analyzed using a specially developed Matlab algorithm for vessel cross-sectional analysis. The cross-sectional area and shape measurements were evaluated to create normograms. Mean cross-sectional size was 53.27±13.31 for the right transverse sinus (TS), 46.87+12.57 for the left TS (p=0.089) and 36.65+12.38 for the superior sagittal sinus. Normograms were created. The distribution of cross-sectional areas along the vessels showed distinct patterns and a parallel course for the median, 25th, 50th and 75th percentiles. In conclusion, using a novel computerized method for vessel cross-sectional analysis we were able to quantitatively characterize dural sinuses of healthy persons and create normograms.

Hypsometric analysis of mid-himalayan watershed using geomatics

Hypsometric analysis describes the distribution of horizontal cross-sectional area of watershed morphology with respect to elevation (areaaltitude analysis). In geologic time scale youth, mature and old geologic stage represents peculiar hypsometric forms of watershed. The hypsometric analysis give picture about pertinent condition of transition from youth to old stage of watershed. Hypsometric characteristics of a watershed plays important role in the dynamics of surface and subsurface runoff generation and resulting soil erosion and denudation processes. Hypsometry is essential aid to measure and represent the form of a watershed and its evolution. Aim of the paper is to carry out the hypsometric analysis of Naula watershed, situated in mid Himalayan region of Uttarakhand using remote sensing and GIS technologies. Hypsometric data were derived and analyzed for Naula watershed from the 1 arc-second Cartosat-1 DEM. In the present study hypsometric integral was found as 0.357, which is indicative of existence of 35.7% of original rock mass of Naula watershed.

Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI.

Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry. We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan geometry. Four-dimensional flow MRI was acquired in 10 Fontan patients (age: 16 ± 4years [mean ± standard deviation], range: 9-21years). The Fontan connection was isolated by 3-D segmentation to evaluate flow distribution from the inferior vena cava (IVC) and superior vena cava (SVC) to the left and right pulmonary arteries (LPA, RPA) and to characterize geometry (cross-sectional area, caval offset, vessel angle). Flow distribution results indicated SVC flow tended toward the RPA while IVC flow was more evenly distributed (SVC to RPA: 78% ± 28 [9-100], IVC to LPA: 54% ± 28 [4-98]). There was a significant relationship between pulmonary artery cross-sectional area and flow distribution (IVC to RPA: R(2)=0.50, P=0.02; SVC to LPA: R(2)=0.81, P=0.0004). Good agreement was found between observers and for flow distribution when compared to net flow values. Four-dimensional flow MRI was able to detect relationships between flow distribution and vessel geometry. Future studies are warranted to investigate the potential of patient specific hemodynamic analysis to improve diagnostic capability.

Numerical study of the effect of the nasal cycle on unilateral nasal resistance

We used computational fluid dynamics to study the effects of the nasal cycle on the modification of unilateral nasal resistance using nasal cavity models from 2 different patients with chronic rhinosinusitis. A steady airflow field with an inspiratory flow rate of 250mL/s was simulated using ANSYS-FLUENT v14.5. The distribution of local unilateral nasal resistance showed different shapes of variation and magnitudes of resistance depending on the distribution of cross-sectional area in the nasal cavity models. The highest local resistance on the congested side was found near the nasal valve area in the first patient, whereas the highest value was found in the nasal vestibule for the second patient. The relative importance of nasal resistance in the turbinated air passage differed for the 2 patients. The unilateral resistance of the congested state was in the range of 0.0229–0.221Pas/mL. In the inferior meatus, greater flow rate was allowed during the congested state than during the decongested state if an extensive backflow developed.

IMPACT OF NITROGEN ON VEGETATIVE GROWTH OF MATURE PEACH TREES IN A SUBTROPICAL CLIMATE

The current Florida peach industry is predominantly located in a subtropical climate, and fertilization regimes developed in temperate climates may not fulfill the nutritional demand for extended postharvest vegetative growth. The objective of this research was to determine the optimal rate of nitrogen fertilizer for mature trees in a subtropical environment. Four rates of nitrogen (N) plus a control (0 kg ha-1 of N) were applied to six-year-old ‘TropicBeauty’ A— ‘Flordaguard’ and included: 45, 90, 179, and 269 kg ha-1 of N applied annually during the 2011 and 2012 growing season. Vegetative growth measurements included trunk cross-sectional area (TCSA), vegetative and floral bud distribution on 1-year-old growth, pruning weights, total leaf N content and chlorophyll content. TCSA and pruning weights were not statistically different; however, trees with 0, 45, and 90 kg ha-1 of N tended to be smaller than those receiving 179 and 269 kg ha-1 of N annually. Vegetative and floral buds were fewer in trees receiving the low N rates (0 and 45 kg ha-1 of N) with high numbers of blind nodes in all treatments. Leaf N concentration was lower in the 0 and 45 kg ha-1 of N treatments (3.7%) than the highest two N treatments (4.1%). Although trees in the lowest N treatments contained seemingly adequate leaf N concentration, decreasing vegetative and floral buds over subsequent years may lead to smaller trees with reduced yield, while trees with higher rates of N produced larger canopies, requiring more severe pruning to maintain productivity.

Superior Oblique Extraocular Muscle Shape in Superior Oblique Palsy

To investigate the superior oblique (SO) extraocular muscle cross section in normal controls and in SO palsy using high-resolution magnetic resonance imaging (MRI). Prospective observational study. At a single academic medical center, high-resolution MRI was obtained at 312μm in-plane resolution using surface coils in multiple, contiguous, quasi-coronal planes perpendicular to the orbital axis in 12 controls and 62 subjects with SO palsy. Previous strabismus surgery was excluded. Imaging was repeated in central gaze and infraduction. In each image plane along the SO, its cross section was outlined to compute cross-sectional area and the major and minor axes of the best-fitting ellipse. Main outcome measures were SO morphology and ocular motility. The major and minor axes, cross-sectional area distributions, and volume of the SO belly were subnormal in orbits with SO palsy at most anteroposterior locations (P= .001), but discriminant analysis showed that palsied SO cross sections segregated distinctly into round and elongate shapes representing isotropic vs anisotropic atrophy, respectively. The major axis was relatively preserved in anisotropic atrophy (P= .0146). Cases with isotropic atrophy exhibited greater hypertropia in infraversion than central gaze, as well as greater excyclotorsion, than cases with anisotropic atrophy (P < .05 forall). Characteristic differences in shape of the palsied SO belly correlate with different clinical features, and may reflect both the degree of differential pathology inthe medial vs lateral neuromuscular SO compartments and the basis for diversity in patterns of resulting hypertropia.

Neuronal nitric oxide synthase is dislocated in type I fibers of myalgic muscle but can recover with physical exercise training.

Trapezius myalgia is the most common type of chronic neck pain. While physical exercise reduces pain and improves muscle function, the underlying mechanisms remain unclear. Nitric oxide (NO) signaling is important in modulating cellular function, and a dysfunctional neuronal NO synthase (nNOS) may contribute to an ineffective muscle function. This study investigated nNOS expression and localization in chronically painful muscle. Forty-one women clinically diagnosed with trapezius myalgia (MYA) and 18 healthy controls (CON) were included in the case-control study. Subsequently, MYA were randomly assigned to either 10 weeks of specific strength training (SST, n = 18), general fitness training (GFT, n = 15), or health information (REF, n = 8). Distribution of fiber type, cross-sectional area, and sarcolemmal nNOS expression did not differ between MYA and CON. However, MYA showed increased sarcoplasmic nNOS localization (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) compared with CON. SST resulted in a decrease of sarcoplasm-localized nNOS following training (before 18.1 ± 12 versus after 12.0 ± 12%; P = 0,027). We demonstrate that myalgic muscle displays altered nNOS localization and that 10 weeks of strength training normalize these disruptions, which supports previous findings of impaired muscle oxygenation during work tasks and reduced pain following exercise.

トンネル内列車通過時圧力変動の数値シミュレーション

When a train travels through a tunnel at high speed, large pressure variations, which act on tunnel lining, equipments inside the tunnel, and the train, are generated in the tunnel. To predict these pressure variations, numerical simulations have been developed. Usually, one-dimensional simulations are used for such purposes. Although the pressure variations caused by the pressure waves can be calculated accurately by one-dimensional simulations, they can underestimate the pressure variations in the area very close to the passing train. The resulting accuracy can be increased by using computational fluid dynamics (CFD), but CFD requires high computational costs. Therefore, this paper proposes a three-dimensional but an efficient method to calculate accurately the pressure variation in the area very close to the passing train in the tunnel. It takes into account the distribution of cross-sectional areas of the train nose and treats the flow around the train nose as three-dimensional potential flow, and the upstream and downstream boundary conditions are specified by a one-dimensional simulation in order to calculate the effect of the pressure waves. The results by this method agree well with those of model experiments by using axisymmetric train model although the discrepancy to the model experiments by using actual shape train still remains.

Tracheal tube obstruction in mechanically ventilated patients assessed by high-resolution computed tomography.

Tracheal intubation compromises mucus clearance and secretions accumulate inside the tracheal tube (TT). The aim of this study was to evaluate with a novel methodology TT luminal obstruction in critically ill patients. This was a three-phase study: (1) the authors collected 20 TTs at extubation. High-resolution computed tomography (CT) was performed to determine cross-sectional area (CSA) and mucus distribution within the TT; (2) five TTs partially filled with silicone were used to correlate high-resolution CT results and increased airflow resistance; and (3) 20 chest CT scans of intubated patients were reviewed for detection of secretions in ventilated patients' TT. Postextubation TTs showed a maximum CSA reduction of (mean±SD) 24.9±3.9% (range 3.3 to 71.2%) after a median intubation of 4.5 (interquartile range 2.5 to 6.5) days. CSA progressively decreased from oral to lung end of used TTs. The luminal volume of air was different between used and new TTs for all internal diameters (P<0.01 for new vs. used TTs for all studied internal diameters). The relationship between pressure drop and increasing airflow rates was nonlinear and depended on minimum CSA available to ventilation. Weak correlation was found between TT occlusion and days of intubation (R²=0.352, P=0.006). With standard clinical chest CT scans, 6 of 20 TTs showed measurable secretions with a CSA reduction of 24.0±3.9%. TT luminal narrowing is a common finding and correlates with increased airflow resistance. The authors propose high-resolution CT as a novel technique to visualize and quantify secretions collected within the TT lumen.

Aging alters contractile properties and fiber morphology in pigeon skeletal muscle.

In this study, we tested the hypothesis that skeletal muscle from pigeons would display age-related alterations in isometric force and contractile parameters as well as a shift of the single muscle fiber cross-sectional area (CSA) distribution toward smaller fiber sizes. Maximal force output, twitch contraction durations and the force-frequency relationship were determined in tensor propatagialis pars biceps muscle from young 3-year-old pigeons, middle-aged 18-year-old pigeons, and aged 30-year-old pigeons. The fiber CSA distribution was determined by planimetry from muscle sections stained with hematoxylin and eosin. Maximal force output of twitch and tetanic contractions was greatest in muscles from young pigeons, while the time to peak force of twitch contractions was longest in muscles from aged pigeons. There were no changes in the force-frequency relationship between the age groups. Interestingly, the fiber CSA distribution in aged muscles revealed a greater number of larger sized muscle fibers, which was verified visually in histological images. Middle-aged and aged muscles also displayed a greater amount of slow myosin containing muscle fibers. These data demonstrate that muscles from middle-aged and aged pigeons are susceptible to alterations in contractile properties that are consistent with aging, including lower force production and longer contraction durations. These functional changes were supported by the appearance of slow myosin containing muscle fibers in muscles from middle-aged and aged pigeons. Therefore, the pigeon may represent an appropriate animal model for the study of aging-related alterations in skeletal muscle function and structure.

Relative distribution of quadriceps head anatomical cross-sectional areas and volumes—Sensitivity to pain and to training intervention

IntroductionQuadriceps heads are important in biomechanical stabilization and in the pathogenesis osteoarthritis of the knee. This is the first study to explore the relative distribution of quadriceps head anatomical cross-sectional areas (ACSA) and volumes, and their response to pain and to training intervention. MethodsThe relative proportions of quadriceps heads were determined in 48 Osteoarthritis Initiative participants with unilateral pain (65% women; age 45–78 years). Quadriceps head volumes were also measured in 35 untrained women (45–55 years) before and after 12-week training intervention. Cross-sectional areas of the vastus medialis (VM), inter-medius (VIM), and lateralis (VL), and of the rectus femoris (RF) were determined from axial T1-weighted MR images. ResultsThe proportion of the VM on the total quadriceps ACSA increased from proximal to distal. The difference in quadriceps ACSA of painful (vs. pain-free) limbs was −5.4% for the VM (p<0.001), −6.8% for the VL (p<0.01), −2.8% for the VIM (p=0.06), and +3.4% for the RF (p=0.67) but the VM/VL ratio was not significantly altered. The muscle volume increase during training intervention was +4.2% (p<0.05) for VM, +1.3% for VL, +2.0% for VIM (p<0.05) and +1.6% for RF. ConclusionThe proportion of quadriceps head relative to total muscle ACSA and volume depends on the anatomical level studied. The results suggest that there may be a differential response of the quadriceps heads to pain-induced atrophy and to training-related hypertrophy. Studies in larger samples are needed to ascertain whether the observed differences in response to pain and training are statistically and clinically significant.

Orientation-dependent section distributions for convex bodies

In the paper the orientation dependent chord length distribution functions for some bounded convex domains are obtained. In particular, formulae for the orientation dependent chord length distributions for a regular polygon and an ellipse are obtained. Explicit forms of the orientation dependent chord length distributions were known only in the cases of a disc and a triangle. We also obtain the cross-section area distribution functions for an ellipsoid and a cylinder. The cross-section area distribution function was known only in the case of a ball.

Corrosion-Induced Concrete Cracking, Steel-Concrete Bond Loss, and Mechanical Degradation of Steel Bars

This study experimentally investigated corrosion-induced deterioration in reinforced concrete (RC) structures: concrete cover cracking, steel-concrete bond loss, and mechanical degradation of corroded steel bars. Pullout and RC beam specimens were prepared, subjected to accelerated corrosion in a wet sand bath, and tested under loading. A 3D laser scan was employed to measure the surface profile of corroded steel bars and determine the corrosion effect on the distribution of residual cross section area. The crack width on the concrete surface was sampled randomly and analyzed statistically. Corrosion reduced the bond strength between steel bars and concrete, particularly in the form of corrosion-induced number and width of cracks. Both the yield and ultimate strengths depended upon the critical cross sectional area of steel bars, whereas the elongation changed with the cross section distribution over the length of the steel bars. Corrosion also changed the distribution of the cross sectional area of steel bars. The crack width on the concrete surface can be well represented by a normal distribution regardless of corrosion levels.

Supersonic Wing–Body Two-Level Wave Drag Optimization Using Extended Far-Field Composite-Element Methodology

The wave drag is an important factor that affects the supersonic flight efficiency and is closely related to the aircraft’s cross-sectional area distribution. A reasonable cross-sectional area distribution determines supersonic aircraft wave drag reduction. In this paper, an exploration of the supersonic aircraft wing–body shape parameterization using the class-shape-refinement-transformation technique and the method of extended far-field composite-element (EFCE) supersonic wing–body wave drag optimization are proposed. The method was applied to a supersonic civil transport wing–body shape optimization, yielding a 40.5% reduction of wave drag coefficient. In this way, the goal of reducing the wave drag in sufficient precision without any lift penalty was achieved. The EFCE wave drag optimization method is available in the conceptual design process of supersonic cruise aircraft to achieve high lift-to-drag ratio characteristics in supersonic flight conditions.

Performance Studies of Polysulfone-Based Membrane: Effect of Silica Morphology

In the present work, polysulfone (PSf) ultrafiltration membranes were prepared by solution casting. The effects of rice husk silica (RHS) on the surface properties of the PSf/Polyethylene glycol (PEG) membrane were observed and investigated. Characterizations were conducted to determine the membrane cross-section area and RHS distribution. The structure of RHS and morphology of membrane were analyzed by using X-ray diffractometer (XRD) and scanning electron microscope (SEM). XRD pattern showed that the amorphous silica was produced from rice husk ash (RHA). The analysis of SEM indicates that the addition of RHS obviously changed the microstructure of the membrane especially at top layer and sub layer.

Effect of hydrogel particle additives on water-accessible pore structure of sandy soils: A custom pressure plate apparatus and capillary bundle model

To probe the effects of hydrogel particle additives on the water-accessible pore structure of sandy soils, we introduce a custom pressure plate method in which the volume of water expelled from a wet granular packing is measured as a function of applied pressure. Using a capillary bundle model, we show that the differential change in retained water per pressure increment is directly related to the cumulative cross-sectional area distribution f(r) of the water-accessible pores with radii less than r. This is validated by measurements of water expelled from a model sandy soil composed of 2-mm-diameter glass beads. In particular, it is found that the expelled water is dramatically dependent on sample height and that analysis using the capillary bundle model gives the same pore size distribution for all samples. The distribution is found to be approximately log normal, and the total cross-sectional area fraction of the accessible pore space is found to be f(0)=0.34. We then report on how the pore distribution and total water-accessible area fraction are affected by superabsorbent hydrogel particle additives, uniformly mixed into a fixed-height sample at varying concentrations. Under both fixed volume and free swelling conditions, the total area fraction of water-accessible pore space in a packing decreases exponentially as the gel concentration increases. The size distribution of the pores is significantly modified by the swollen hydrogel particles, such that large pores are clogged while small pores are formed.

Generalized Correlations for Heat Transfer through High Performance Fins

Analysis of heat transfer through different candidates for high performance fins is considered in this work. These candidates are: (A) fins of constant cross-sectional area, (B) fins of constant cross-sectional area gradient, and (C) radial fins with power-law cross-sectional area distribution. The types (A) and (B) fins are allowed having variable power-law profile distributions. The energy equation for each case is solved analytically, and closed form equations for various performance indicators including the fin efficiency are obtained. It is identified that high performance fins are those fins having larger tip and surface areas and smaller tip thickness than those of the straight fin. These effects tend to augment the fin heat transfer rate. One of the indicators of the type (A) fins is found to become dependent on the tip thickness when it is smaller than the base thickness and for thermal lengths larger than 1.5. The type (C) fins are found to transfer more thermal energy than the type (B) fins under same tip area and tip thickness. Finally, generalized correlations for the fin efficiency of high performance fins as function of base and tip areas and thicknesses and the thermal length are proposed and validated.

Prolonged C2spinal hemisection-induced inactivity reduces diaphragm muscle specific force with modest, selective atrophy of type IIx and/or IIb fibers

The diaphragm muscle (DIAm) is critically responsible for sustaining ventilation. Previously we showed in a commonly used model of spinal cord injury, unilateral spinal cord hemisection at C(2) (SH), that there are minimal changes to muscle fiber cross-sectional area (CSA) and fiber type distribution following 14 days of SH-induced ipsilateral DIAm inactivity. In the present study, effects of long-term SH-induced inactivity on DIAm fiber size and force were examined. We hypothesized that prolonged inactivity would not result in substantial DIAm atrophy or force loss. Adult rats were randomized to control or SH groups (n = 34 total). Chronic bilateral DIAm electromyographic (EMG) activity was monitored during resting breathing. Minimal levels of spontaneous recovery of ipsilateral DIAm EMG activity were evident in 42% of SH rats (<25% of preinjury root mean square amplitude). Following 42 days of SH, DIAm specific force was reduced 39%. There was no difference in CSA for type I or IIa DIAm fibers in SH rats compared with age, weight-matched controls (classification based on myosin heavy chain isoform expression). Type IIx and/or IIb DIAm fibers displayed a modest 20% reduction in CSA (P < 0.05). Overall, there were no differences in the distribution of fiber types or the contribution of each fiber type to the total DIAm CSA. These data indicate that reduced specific force following prolonged inactivity of the DIAm is associated with modest, fiber type selective adaptations in muscle fiber size and fiber type distribution.

Hydraulic design and performance analysis of low specific speed centrifugal pump

Since low specific speed centrifugal pump with long narrow flow divergent channels has positive slope of head-capacity characteristic curve, low flow rate instability and high flow rate power overload, special events about its hydraulic design are still under study. This paper demonstrates a method for hydraulic design of low specific speed centrifugal pump complex impeller (with splitter blades) which is based on 2D flow theory. In this method, obtain the basic geometry parameters by empirical correlation, adjust impeller profile according to given flow cross section area distribution and wrapping angles distribution, relate the position of splitter blades to slip factor. Based on this method, low specific speed centrifugal pump impellers have been designed using the same design parameters (Head, Capacity, Rotation Speed, etc) with different factors. And 3D turbulent flow fields in design pumps have been solved by using RANS equations with RNG k-epsilon turbulence model. The investigation to the effects of different splitter blades on velocity distributions and pressure distributions along the flow channels and hydraulic performance of centrifugal pumps are presented. The result shows that properly placed splitter blades by choosing suitable design factors will improve the flow in the pump and enhance the hydraulic performance of it.