Longitudinal Axis Parallel Research Articles

Stable orientations of small-scale floating cylinders

A coin always floats in stable equilibrium with its longitudinal axis normal to the air–liquid interface. In contrast, a long thin cylindrical pin floats with its longitudinal axis parallel to the air–liquid interface. In this context, we present a theoretical investigation of the stability of small-scale hydrophobic cylinders floating in vertical and horizontal orientations at various aspect ratios (length/diameter). The study is limited to cylinders denser than water floating at the air–water interface. Our analysis shows that, unlike large-scale vertically floating cylinders, the stability of vertically orientated small-scale cylinders increases with an increase in aspect ratio. A similar trend is observed in the stability of small-scale horizontal cylinders. We also explain the underlying mechanics that leads to a rise in the stability of floating cylinders with an increase in aspect ratio. Unlike large-scale floating cylinders with uniform density, we show that the effect of governing forces (weight, buoyancy and surface tension) in small-scale cylinders changes from a stabilising to a destabilising force with a change in the aspect ratio. For example, in the case of a vertically floating cylinder, the buoyancy force acts as a stabilising force at a small aspect ratio whereas, at large aspect ratios, the buoyancy force has a destabilising influence. Likewise, the body's weight has a destabilising influence at a small aspect ratio and stabilising effect at a large aspect ratio. The reason behind this transformation is that, above a particular aspect ratio, the centre of gravity of small-scale floating cylinders lies below the centre of buoyancy.

Surgical treatment of multiple large tuberous xanthomas in familial hypercholesterolemia: A case report

Introduction and importanceXanthomas are a rare condition with the appearance of exogenous masses on the body, and it is common in patients with familial hypercholesterolemia (FH). For multiple large xanthomas, surgical excision is optimal to improve the patient's quality of life.Case presentationA 34-year-old male patient presented with multiple large tuberous xanthomas related to FH. There were 15 masses in different body parts, including the dorsum of the hands, elbows, buttocks, feet, and Achille's tendon. The largest masses in the buttocks measured 8 × 8 × 5 cm. Surgical removal of 13 masses was carried out in combination with medical treatment. The skin incision was oval around the circumference of masses with the longitudinal axis parallel to the Langer's line. Skin defects were closed directly or dissected on both sides of the incision to reduce tension. Wound healing was normal. After 1.5 months, there was no recurrence of xanthomas.Clinical discussionSurgical treatment easily removes the entire tuberous xanthomas. The healing process is completely normal. Resection should be indicated for tuberous xanthomas that cause negative functional and aesthetic effects. Besides, lipid-lowering therapy is necessary to prevent tuberous xanthomas recurrence as well as premature coronary artery diseases.ConclusionSurgical treatment of patients with multiple large tuberous xanthomas related to familial hypercholesterolemia was performed safely and successfully. After 1.5 months of follow-up, the wound healed well and no recurrence of xanthomas was detected. We recommend that a further study is needed to investigate post-treatment recurrence for multiple large xanthomas.

Orienting to the sun improves camouflage for bilaterally symmetrical prey

Abstract Here, we investigate the camouflage consequences of animal orientation behaviour. Shadows can be a conspicuous cue to the presence of prey. For bilaterally symmetrical animals, light field modelling indicates that camouflage will be improved when an animal orients its longitudinal axis directly towards or away from the sun, because the appearance of shadows is minimized. We test this prediction with a field predation experiment, in which wild birds hunt for artificial camouflaged prey oriented with the longitudinal axis either parallel or perpendicular to the sun. We find that prey oriented parallel to the sun are 3.93 times more likely to survive than prey oriented perpendicular to the sun. This result demonstrates the strong orientation dependence of camouflage. Given the dramatic difference in survival of prey with different orientations, we suggest that camouflage should be investigated as an important determinant of the positional behaviour of animals.

Near-field spatial and temporal blast pressure distributions from non-spherical charges: Horizontally-aligned cylinders

Research into the characterisation of blast loading on structures following the detonation of a high explosive commonly assumes that the charge is spherical. This has the advantage of simplifying experimental, analytical and computational studies. In practice, however, designers of protective structures must often consider explosive threats which have other geometric forms, which has significant influence on the loading imparted to structures very close to the explosion source. Hitherto, there has been little definitive experimental investigation of the ‘near-field’ blast load parameters from non-spherical explosive charges and studies that have been conducted are usually confined to measurement of the total impulse imparted to a target. Currently, a detailed understanding of the development of loading on a target, necessary to fully inform the design process and appraise the efficacy of predictions from computational models, is lacking. This article, the first part of a wider investigation into these geometrical effects, details work conducted to address this deficiency. Results are presented from an experimental study of loading from detonations of cylindrical charges, set with the longitudinal axis parallel to an effectively rigid target, instrumented to facilitate the capture of the spatial and temporal evolution of the loading at different radial and angular offsets from the charge. These results are compared against loads from spherical charges and the effect of charge shape is identified. Significant differences are observed in the mechanisms and magnitude of loading from cylindrical and spherical charges, which is confirmed through the use of numerical analysis. The overall study provides insights which will assist the future design of effective protection systems.

Laser Metal Fused Al Alloy Processed Using Different Heat Treatments

Tensile and dilatometric specimens were obtained with longitudinal axis parallel to the building direction. A first set of samples has been directly aged in the as- built state (AB) while a second batch underwent solubilization annealing (SA) at 540°C for 60min just before artificial ageing (AA) at 160°C for 8h. Solubilization caused the precipitation of Si particles, suppressed by the rapid solidification during SLM. Moreover, it caused partial recrystallization leading to a coarser microstructure. The ageing response resulted very different in the two cases, involving a higher starting hardness for the as-built material, showing a markedly higher hardness during the whole process. In the as built (AB) material, isochronal ageing experiments carried out by differential scanning calorimetry showed the precipitation of Mg2Si particles beneath Si, while the same transformations were much less intense in the solubilized sample, due to the lower Si supersaturation. The ageing process raised the yield strength of about 20% compared to the AB material, slightly reducing the fracture elongation.

Properties of Laser Metal Fused AlSi10Mg Alloy Processed Using Different Heat Treatments

The AlSi10Mg alloy was fabricated by Laser Metal Fusion (LMF) using different post processing conditions. Tensile and dilatometric specimens were obtained with longitudinal axis parallel to the building direction. A first set of samples was directly aged in the as-built state (AB), while a second batch underwent solubilization annealing (SA) at 540 °C for 60 min just before artificial ageing (AA) at 160 °C for 8 h. Solubilization caused the precipitation of Si particles, suppressed by the rapid solidification during SLM. Moreover, it caused partial recrystallization leading to a coarser microstructure. The ageing response was very different in the two cases, involving a higher starting hardness for the as-built material, showing a markedly higher hardness during the whole process. In the as-built material, isochronal ageing experiments carried out by differential scanning calorimetry showed the precipitation of Mg2Si particles beneath Si, while the same transformations were much less intense in the solubilized sample, due to the lower Si supersaturation. The ageing process raised the yield strength of about 20% compared to the AB material, slightly reducing the fracture elongation. The same alloy after SA+AA showed a strength 25% lower than the AB+AA material, while ductility significantly increased.

Analysis of Three Commonly Used Tibia Length Measurement Techniques

This study analyzes three tibia length measurement techniques on a sample of 107 tibiae. Two of the techniques meet published criteria by resting the tibia on its posterior surface with the longitudinal axis parallel to an osteometric board. The third technique does not adequately keep the longitudinal axis parallel to the board. Statistical analyses show low levels of interobserver error for all techniques and statistically significant differences between the third technique and the other two techniques. Results report a maximum difference of 6 mm between measurement techniques with the third technique having greater than 95% directional bias. A survey sent out to the American Academy of Forensic Sciences forensic anthropology community reported more than 50% of respondents having been taught the third technique when an osteometric board with a slot/hole is not available. The intermixing of the third technique with the other two has likely contributed to higher levels of interobserver error in tibia length measurements.

Laterally Placed CDRA with Triangular Notches for Ultra Wideband Applications

AbstractIn this paper, a Coaxial probe-fed Laterally placed Cylindrical Dielectric Resonator Antenna (LCDRA) with symmetrical triangular notches is presented. The lateral surface of the Cylindrical Dielectric Resonator Antenna (CDRA) is kept on the ground plane with its longitudinal axis parallel to the ground plane. LCDRA has a lower resonant frequency than the CDRA and it offers considerably wider impedance bandwidth than CDRA. Finally, two symmetrical triangular notches are introduced on the two edges of LCDRA which is perpendicular to the axis to further improve the impedance bandwidth. The proposed antenna offers a wide impedance bandwidth (

Fabrication and design of bioactive agent coated, highly-aligned electrospun matrices for nerve tissue engineering: Preparation, characterization and application

Abstract In this study, we designed highly-aligned thermoplastic polycarbonate urethane (PCU) fibrous scaffolds coated with bioactive compounds, such as Poly- l -Lysine (PLL) and Poly- l -Ornithine (PLO), to enhance cellular adhesion and directivity. These products were characterized by scanning electron microscope (SEM) analysis which demonstrated that highly aligned fiber strands were formed without beads when coated onto a mandrel rotating at 1800 rpm. During in vitro cell test, PLO-coated, aligned PCU scaffolds were found to have significantly higher proliferation rates than PLL coated and bare PCU scaffolds. Interestingly, dental pulp stem cells (DPSCs) were observed to stretch along the longitudinal axis parallel to the cell direction on highly aligned scaffolds. These results clearly confirm that our strategy may suggest a useful paradigm by inducing neural tissue repair as a means to remodeling and healing of tissue for restorative procedures in neural tissue engineering.

Effect of Rolling Direction to the Strength of a Thin-Walled Steel SHS Beam under Concentrated-Compressive Load and Bending Moment

In this research, it has been carried out the development of a strength analytical method of a thin-walled steel square pipe (Square Hollow Section/SHS) affected by the interaction of concentrated-compressive load and bending moment then it verified by experimental approach. The experimental approach was consisted of measuring a basic material property and the strength of the investigated SHS pipe. The basic material property identified parallel to rolling direction (0o) and perpendicular to rolling direction (90o). The analytical data obtained from cut-off strength method is generally scattered within the acceptable limits of ± 20 % and tends to be in unconservative region. The actual data measured from experiments shows that SHS beam with t = 0.6 mm and longitudinal axis parallel to the rolling direction of base material has higher strength compared to the one of the SHS beam with t= 0.6 mm and longitudinal axis perpendicular to the rolling direction, meanwhile the SHS beam with t= 1.2 mm is tends to be equal. This means that the rolling direction of base material can be considered to be a parameter in the strength design of a thin-walled SHS beam

Effect of Rolling Direction to the Strength of a Thin-Walled Steel SHS Beam under Concentrated-Compressive Load and Bending Moment

In this research, it has been carried out the development of a strength analytical method of a thin-walled steel square pipe (Square Hollow Section/SHS) affected by the interaction of concentrated-compressive load and bending moment then it verified by experimental approach. The experimental approach was consisted of measuring a basic material property and the strength of the investigated SHS pipe. The basic material property identified parallel to rolling direction (0o) and perpendicular to rolling direction (90o). The analytical data obtained from cut-off strength method is generally scattered within the acceptable limits of ± 20 % and tends to be in unconservative region. The actual data measured from experiments shows that SHS beam with t = 0.6 mm and longitudinal axis parallel to the rolling direction of base material has higher strength compared to the one of the SHS beam with t= 0.6 mm and longitudinal axis perpendicular to the rolling direction, meanwhile the SHS beam with t= 1.2 mm is tends to be equal. This means that the rolling direction of base material can be considered to be a parameter in the strength design of a thin-walled SHS beam

Tip-enhanced Raman spectroscopy of 4,4′-bipyridine and 4,4′-bipyridine N,N'-dioxide adsorbed on gold thin films

A tip-enhanced Raman spectroscopy (TERS) set-up added on a scanning tunneling microscope (STM) was constructed and was used to study the molecular arrangement of 4,4′-bipyridine (4,4′-BiPy) and 4,4′-bipyridine N,N'-dioxide (4,4′-BiPyO2) adsorbed on Au(111). Over a monolayer of 4,4′-BiPy, in the ambient atmosphere, intense TERS signals were recorded, involving AuN stretching vibration at 185cm−1. At the early stage of 4,4′-BiPy adsorption, the AuN stretching signal was not detected. By the aid of the theoretical calculations of the Raman scattering intensities for each vibrational normal mode, a standing-up, tilted orientation at monolayer coverage and a vertical orientation with the longitudinal molecular axis parallel to the surface at low surface coverage was concluded. Adsorption of 4,4′-BiPyO2 on Au(111) resulted in formation of a (6×9) adlattice. Moderately intense TERS signals were observed, containing the NO stretching modes and the in-plane ring vibrational modes. Neither AuO nor AuN stretching modes were observed. 4,4′-BiPyO2 was laid with the longitudinal axis parallel to the surface, and the molecular plane vertical to the surface. These results demonstrate that STM-TERS is an effective method for simultaneous imaging and vibrational analysis, facilitating identification of the adsorbed layers with the nanometer-scale spatial resolution and monolayer sensitivity.

Motion deviation rectifying method of dynamically measuring rail wear based on multi-line structured-light vision

Rail wear dynamic measurement techniques are important to ensure the security of railway system and the efficiency of maintaining. Nowadays, a widely used approach is based on structured-light vision sensor, which includes a camera and a laser projector generating a light plane on the inner side of the rail. Considering the sensor installation error and vibration of running train, it is difficult to ensure the perpendicularity between the light plane and the rail, which leads to large measurement error. In order to overcome the problem, a motion deviation rectifying method is proposed. Rail section profiles are obtained by a multi-line structured-light vision sensor with multiple parallel light planes. Each profile can be segmented into two curves. One representing the rail waist is used to fit the rail longitudinal axis (parallel to train running direction) and establish an auxiliary plane perpendicular to the direction. Deviation rectifying process is to project the rail section profiles onto the auxiliary plane to recover perpendicularity between the light plane and the rail. Then another curve representing the rail head is used to calculate the rail wear based on the standard profile. The experimental results indicate that the method reduces the rail wear measurement error, meeting the requirements for real-time dynamic measurement of rail wear.

Long-Range Alignment of Gold Nanorods in Electrospun Polymer Nano/Microfibers

In this study, a scalable fabrication technique for controlling and maintaining the nanoscale orientation of gold nanorods (GNRs) with long-range macroscale order has been achieved through electrospinning. The volume fraction of GNRs with an average aspect ratio of 3.1 is varied from 0.006 to 0.045 in aqueous poly(ethylene oxide) solutions to generate electrospun fibers possessing different GNR concentrations and measuring 40-3000 nm in diameter. The GNRs within these fibers exhibit excellent alignment with their longitudinal axis parallel to the fiber axis n. According to microscopy analysis, the average deviant angle between the GNR axis and n increases modestly from 3.8 to 13.3° as the fiber diameter increases. Complementary electron diffraction measurements confirm preferred orientation of the {100} GNR planes. Optical absorbance spectroscopy measurements reveal that the longitudinal surface plasmon resonance bands of the aligned GNRs depend on the polarization angle and that maximum extinction occurs when the polarization is parallel to n.

Hyalinizing Cholecystitis and Associated Carcinomas

We describe a clinicopathologically distinct subtype of cholecystitis, the extensively calcific version of which has been presented in the clinical literature as "porcelain gallbladder (PG)." This cholecystitis, which we propose to refer to as hyalinizing cholecystitis (HC), is characterized by dense, paucicellular hyaline fibrosis transforming the gallbladder (GB) wall into a relatively thin and uniform band. The process diffusely effaces most of the normal structures of GB, and some cases show calcifications. To determine the clinicopathologic associations of HC, we systematically analyzed 4231 cholecystectomies (606 of which had carcinoma) histopathologically, in addition to a targeted search in our databases. Ninety-six cases of HC were identified (1.6% of cholecystectomies). Patients with HC were a decade older than ordinary cholecystitis patients (56 vs. 47; P<0.001), suggesting that HC may be a long-term complication of chronic injury in some patients. Calcifications of variable amounts and degrees were identified in two thirds of the cases. In addition, 10 cases showed diffuse marked calcifications and were considered separately as "complete porcelain" GB. Thirty-eight HC cases had carcinoma with a calculated frequency of 15% and an odds ratio of cancer risk of 4.6. Only 42% of the invasive cases were associated with calcifications; none of the 10 diffusely calcific cases had carcinoma. HC-related carcinomas were challenging diagnostically. They did not form distinct masses or any significant thickening (mean thickness, 2.6 vs. 4.0 mm in ordinary adenocarcinomas; P<0.002). Microscopically, they had widely scattered and bland-appearing glands embedded in the thin band of hyaline stroma of HC, commonly showing a disappearing lining, leaving behind the granular, necrotic intraluminal debris (regression) with or without calcifications, which could be the only sign of cancer in some sections. The morphologic features that allowed the recognition of these glands as malignant included their longitudinal axis parallel to the surface, their irregular contours, clear cytoplasm with distinct borders, nuclear irregularities, and washed-off chromatin. Surface epithelium, if preserved (and it was not in most cases), typically showed carcinoma in situ of either denuding or micropapillary types. HC-associated carcinomas, with a median survival of 7 months, appeared to have a clinical course at least as aggressive as that of regular carcinomas (median survival 12 months; P=0.02). In conclusion, HC is a distinct clinicopathologic entity, which is often associated with carcinoma, and the carcinomas arising from this group are often very subtle and prone to misdiagnosis microscopically. As HC is typically devoid of epithelium, any glandular elements on the wall of HC should be regarded as a suspect for carcinoma. This study also confirms recent findings in the radiology literature-it is not the complete (diffusely calcific) PG that is associated with cancer. Instead, a distinct, histopathologically defined form of cholecystitis, HC with minimal or no calcifications (incomplete PG), is associated with invasive carcinoma. Thus, imaging protocols ought to focus on the correlates of HC rather than fixating on calcifications. Further studies into the pathogenesis of this process and its mechanisms of progression to carcinoma are warranted.

Mechanical properties and in vivo behavior of a biodegradable synthetic polymer microfiber–extracellular matrix hydrogel biohybrid scaffold

A biohybrid composite consisting of extracellular matrix (ECM) gel from porcine dermal tissue and biodegradable elastomeric fibers was generated and evaluated for soft tissue applications. ECM gel possesses attractive biocompatibility and bioactivity with weak mechanical properties and rapid degradation, while electrospun biodegradable poly(ester urethane)urea (PEUU) has good mechanical properties but limited cellular infiltration and tissue integration. A concurrent gel electrospray/polymer electrospinning method was employed to create ECM gel/PEUU fiber composites with attractive mechanical properties, including high flexibility and strength. Electron microscopy revealed a structure of interconnected fibrous layers embedded in ECM gel. Tensile mechanical properties could be tuned by altering the PEUU/ECM weight ratio. Scaffold tensile strengths for PEUU/ECM ratios of 67/33, 72/28 and 80/20 ranged from 80 to 187 kPa in the longitudinal axis (parallel to the collecting mandrel axis) and 41–91 kPa in the circumferential axis with 645–938% breaking strains. The 72/28 biohybrid composite and a control scaffold generated from electrospun PEUU alone were implanted into Lewis rats, replacing a full-thickness abdominal wall defect. At 4 wk, no infection or herniation was found at the implant site. Histological staining showed extensive cellular infiltration into the biohybrid scaffold with the newly developed tissue well integrated with the native periphery, while minimal cellular ingress into the electrospun PEUU scaffold was observed. Mechanical testing of explanted constructs showed evidence of substantial remodeling, with composite scaffolds adopting properties more comparable to the native abdominal wall. The described elastic biohybrid material imparts features of ECM gel bioactivity with PEUU strength and handling to provide a promising composite biomaterial for soft tissue repair and replacement.

Domain wall propagation in single crystalline iron wires

The characterization of magnetization reversal in a magnetic domain wall (DW) in a single crystalline Fe wire with crystalline anisotropy and shape anisotropy has been investigated by the giant magnetoresistance (GMR) measurement. The DW propagation velocity reached about 1 km/s in 110 Oe field at 77 K. The broad distribution of the propagation velocity versus the switching field in the Fe wire with longitudinal axis parallel to the ⟨110⟩ direction was found. The magnetic anisotropy energy including the crystalline and shape anisotropies play an important role in the nucleation and propagation of DW.

Negative donors in bulk Si andSi/SiO2quantum wells in a magnetic field

The spin-singlet ground states of a ${D}^{\ensuremath{-}}$ ion in bulk Si and $\text{Si}/{\text{SiO}}_{2}$ quantum wells have been investigated in the presence of a magnetic field, using a diffusion quantum Monte Carlo method. By neglecting the central-cell correction, the negative donor state can be assigned by the valley indexes of two trapped electrons. In the bulk Si, the ground-state energies of negative donors of both the intervalley and intravalley configurations split into two levels in a magnetic field along the $z$ axis and the lowest-energy state becomes the intervalley configuration of the two electrons in the valleys with their longitudinal axes perpendicular to the magnetic field. The magnetic field increases the binding energy of a negative donor and the strongest enhancement is attained for the intravalley configuration of the two electrons in the valley with the longitudinal axis parallel to the magnetic field. In the quantum well with the interface within the $x\text{\ensuremath{-}}y$ plane, the quantum confinement effect changes the lowest-energy state of a negative donor from the intervalley configuration in the bulk to the intravalley configuration for which the binding energy is increased most strongly by the magnetic field perpendicular to the well interface. The central-cell correction on the binding energy of a ${D}^{\ensuremath{-}}$ ion in a quantum well is also discussed.

Phylloclade anatomy in Phyllanthus section Choretropsis (Phyllanthaceae)

The phylloclade anatomy of nine Brazilian species of the genus Phyllanthus section Choretropsis was studied, and its systematic significance was analysed. The arrangement of epidermal cells varied according to the species, with the guard cells of the stomatal apparatus distributed randomly or with the longitudinal axis parallel to the branch. In both branch types, the stomata were distributed on the phylloclade surface, except in P. gladiatus which showed hypostomatic branches. In most of the species, phylloclades developed a vascular system surrounded by clusters of fibres and cortical parenchyma, which could differentiate into palisade-like tissue and ground tissue like a true leaf blade. The distribution of the vascular system followed the cylindrical or flattened diameter shape of the branch. In subsection Choretropsis, the cylindrical branches of P. choretroides, contrary to other species, developed a second ring formed by clusters of fibres surrounded by large parenchymal cells. In subsection Applanata, the palisade-like cells of P. flagelliformis phylloclades acquired an isodiametric shape. The highest level of specialization was observed in P. gladiatus, which developed phylloclades with a dorsiventral structure, a main vein, and small sets of lateral vascular bundles like a typical leaf blade. The tissue arrangement of different species showed a gradual pattern, which was correlated with the different branch morphology and plant architecture. Despite the transitional pattern, it was suggested that some of the phylloclades had an independent origin and convergent evolution in the Choretropsis section. The anatomy of different branch types was shown to be useful, either in isolation or in association with other morphological characters, to delimit the species and to further understand their relationships and phylogeny. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 91–102.

Transverse pelvic rotation during quiet human stance

The mechanism of two-legged quiet stance is unclear. This study specifically investigated biomechanical parameters characterising the mechanisms of rotation around the longitudinal axis (parallel to gravitational acceleration, i.e. in the transverse plane parallel to the ground). Subjects (10) were examined while standing quietly on two force platforms which measured the transverse component of the ground reaction torque (GRT). In addition, right and left hip kinematics were acquired by tracking markers in the sagittal plane. The pelvic rotation in the transverse plane (pelvic angle) was then calculated from the anterior–posterior coordinates of the hip markers. We verified the hypothesis that the pelvis generally may be coupled to the ground by a rotational stiffness provided by both legs. Thus, we asked whether the transverse GRT component may be proportional to the pelvic angle. This hypothesis was rejected. However, the transverse GRT component could be identified as one rotational stabilising mechanism which drove the higher-frequency (>1 Hz) deflections of the pelvic angle back to its lower-frequency fraction. The respective stiffness coefficient between transverse GRT component and relative displacement between higher- and lower-frequency pelvic angular fraction was about 2.4 N m/°. Implications for the character and the localisation of active control of body rotation around the longitudinal axis are discussed.