Axial Type Research Articles

Application of diffusion chambers for cell macroencapsulation: from concept to clinical trials (literature review)

Macroencapsulation of cells allows to isolate the donor biomaterial from the influence of the recipient’s organism. The degree of isolation can vary from mechanical isolation of donor cells within the implantation site to complete immune isolation of the transplanted biological material. The diffusion chamber was the first device used for macroencapsulation. The initial stage of research of this technique was aimed at expanding the range of cell and tissue implantation in allogenic and xenogenic models and clarifying the mechanisms underlying the graft rejection reaction. Later the design of the diffusion chamber underwent a number of changes that determined the modern application of the macroencapsulation method. The derivative of the diffusion chamber – the engineering chamber in complex with the arterio-venous shunt is used as a tissue modeling tool for creation of soft tissue flaps of different composition with the axial type of blood supply. An alternative design of the flow chamber allows the formation of soft tissue flaps on intact vessels. The engineering chamber is also used for growing various types of tissues and organ fragments (cardiac transverse striated muscle tissue, lymphoid tissue, fragments of liver, thymus, pancreas). A separate direction in studying the range of practical applications of the diffusion chamber is the development and testing of methods of transplantation of pancreatic islet cells into animals when creating allo- and xenogeneic experimental models for the treatment of diabetes mellitus. Some devices are already undergoing clinical trials and are available as a product for experimental studies.

Substitution of the Axial Type 1 Cu Ligand Affords Binding of a Water Molecule in Axial Position Affecting Kinetics, Spectral, and Structural Properties of the Small Laccase Ssl1.

Multicopper oxidases use Cu ions as cofactors to oxidize various substrates. High reduction potential at Type 1 Cu is considered as crucial for effective catalysis. Previous studies have shown that replacing the axial methionine ligand of the Type 1 Cu with leucine or phenylalanine leads to an increased reduction potential, but not always to higher enzyme activity. Here we present a study on six variants of the small laccase Ssl1 from Streptomyces sviceus, where the axial methionine ligand was substituted, and the effect of the axial ligand on reduction potential, activity, spectral properties and structure was investigated. Absorption, electronic circular dichroism and EPR spectra revealed the presence of a stronger coordinating axial ligand like oxygen, which influences the electronic and catalytic properties more than the nature of the amino acid side chain. The crystal structures of the Ssl1 variants were solved, which show that none of the amino acid side chains coordinate to the Cu. Instead, a water molecule is found in the axial coordination site, which support the spectroscopic data. Our findings highlight the importance of combining structural and spectroscopic methods to investigate the effect of amino acid exchange on multicopper oxidases.

Critical Impact of Working Distance on OCT Imaging: Correction of Optical Distortion and Its Effects on Measuring Retinal Curvature.

To assess the impact of working distance (WD) on optical distortion in optical coherence tomography (OCT) imaging and to evaluate the effectiveness of optical distortion correction in achieving consistent retinal Bruch's membrane (BM) layer curvature, regardless of variations in WD. Ten subjects underwent OCT imaging with four serial macular volume scans, each employing distinct WD settings adjusted by balancing the sample and reference arm of the OCT interferometer (eye length settings changed). Either of two types of 30° standard objectives (SOs) was used. A ray tracing model was used to correct optical distortion, and BM layer curvature (represented as the second derivative of the curve) was measured. Linear mixed effects (LME) modeling was used to analyze factors associated with BM layer curvature, both before and after distortion correction. WD exhibited significant associations with axial length (β = -1.35, P < 0.001), SO type (P < 0.001), and eye length settings (P < 0.001). After optical distortion correction, the mean ± SD BM layer curvature significantly increased from 16.80 ± 10.08µm-1 to 49.31 ± 7.50µm-1 (P < 0.001). The LME model showed a significant positive association between BM layer curvature and WD (β = 1.94, P < 0.001). After distortion correction, the percentage change in BM layer curvature due to a 1-mm WD alteration decreased from 9.75% to 0.25%. Correcting optical distortion in OCT imaging significantly mitigates the influence of WD on BM layer curvature, enabling a more accurate analysis of posterior eye morphology, especially when variations in WD are unavoidable.

P-type doped AlxGa1-xAs nanowire photocathode: A theoretical perspective on structural and optoelectronic properties

In this work, the effect of p-type doping on the structural, electronic, and optical properties of AlxGa1-xAs nanowires are investigated by first-principles calculations. Different doping elements (Be, Mg, Zn), doping methods (interstitial and substitution doping) and doping concentration are considered. The calculations of formation energy suggest that the structural stability of p-type AlxGa1-xAs nanowires is gradually weaken as the rise of doping concentration and Al composition. Besides, the difficulty of forming substitution doping for different doping elements obeys the following order: Be < Mg < Zn. In addition, the substitution doping atom tends to replace Ga atom rather than Al atom to form substitution doping structure. After substitution doping, all energy bands shift to higher energy region due to the orbital hybridization of electronic states induced by impurity atom and nanowire atoms. Moreover, the substitution doping leads to the Fermi level entering into the valence band, resulting in obviously p-type conductivity. The p-type modulation doping is indeed effective in the axial type AlxGa1-xAs nanowires with p-type carrier concentration varying between 1.85 × 1020 cm−3 and 4.42 × 1020 cm−3, and the conductivity will be further enhanced with increasing substitution doping concentration or Al composition. Finally, the optical absorption of AlxGa1-xAs nanowire photocathodes can be effectively enhanced through BeGa doping. Our findings not only present a comprehensive understanding of p-type doping mechanism of AlxGa1-xAs nanowires, but also provide a theoretical basis for preparing AlxGa1-xAs nanowire based photoelectric devices with p-type properties.

Torque and Eddy Current Behavior of a Magnet Rotating Axial Disk Type Magnetic Coupler: Analysis and Experimental Verification

This research explored the impact of air gap on torque and eddy current behavior of a magnet-north-pole rotating axial disk-type magnetic coupler using the magnetic equivalent circuit method. A magnetic equivalent circuit (MEC) model was developed to analyze the torque and induced eddy current behavior for the magnetic N-pole rotation angle 0° to 30° axial disk type magnetic coupler (MC). Torque equations were derived by combining Kirchhoff's law and the integral method, whereas induced eddy current equations were derived using Ampere's law. Flux leakage reluctance equations were obtained using an integral method. Furthermore, the study conducted 2D finite element simulations, and the results were validated against experimental data to ensure the accuracy and reliability of the proposed MEC model. Finally, the research findings suggested that an air gap length of 4 mm was an optimum length to obtain maximum torque and minimum magnetic saturation effects for a proposed MEC model of N-pole rotating axial disk type MC.

Risk factors for suprachoroidal hemorrhage associated with glaucoma surgery in children: a case–control study

PurposeTo assess the risk factors for suprachoroidal hemorrhage (SCH) following glaucoma surgery in pediatric patients at a tertiary eye center. MethodsThe medical records of 326 patients (326 eyes) who underwent glaucoma surgery between January 2014, and September 2017 were reviewed retrospectively. Seventeen cases with SCH were compared with 309 controls who underwent uneventful glaucoma surgery during the same period. We documented age, sex, baseline intraocular pressure, glaucoma diagnosis, previous surgery, preoperative axial length, pachymetry, lens status and type of glaucoma surgery performed (whether combined with cataract or other glaucoma procedure or being standalone). ResultsOf the 17 cases of SCH, only a single case occurred intraoperatively; the remainder occurred in the early postoperative period. The most frequent diagnosis was primary congenital glaucoma (PCG), accounting for 10 patients (59%) in cases and 247 (80%) in controls, followed by glaucoma associated with nonacquired ocular anomalies, which accounted for 3 cases (18%) and 22 controls (7%). Aphakia and combined surgeries (in the univariate analysis) were found to be possible risk factors for the development of SCH, with none achieving significance in the multivariable analysis. ConclusionsIn our study cohort, combined surgeries as well aphakia were possible risk factors for SCH.

COMPARATIVE WOOD ANATOMY OF FOUR Vernonia delile SPECIES (ASTERACEAE) IN SOUTHWESTERN NIGERIA.

Wood anatomy of four Vernonia Delile species in Southwestern States of Nigeria was investigated with a view to identifying the anatomical features of the genus that could be used to delimit the taxa. Plant samples were collected from Oyo, Ekiti, Osun and Ondo States. Transverse, tangential and radial longitudinal sections were made from the wood of the species of Vernonia using Reichert sliding microtome at 10μm thickness. The woods were also macerated with Schultze's uid to separate the tissues and cells. The macerates and cut sections were stained with Safranine O reagent to reveal the differences in tissue arrangements, shapes and cell inclusions. The four species showed common anatomical features: pore shape at transverse plane are oval, round, rectangular circular to cylindrical, simple pitting of vessel elements and presence of - uniseriate, biseriate and multiseriate rays. The wood characteristics that can be used to distinguish the taxa are absent and presence of : tylose, bre length and percentage of solitary vessel, axial parenchyma type and its absence. These features conferred signicant taxonomic difference in the species and members were categorized into three major groups. These ndings serve as baseline for further research such as molecular studies.

A novel transcoronal surgical technique for the treatment of cystic lesions of the distal phalanx: A cadaveric study.

To assess the feasibility of a novel transcoronal approach for the treatment of axial type 3 cysts of the palmar/plantar aspect of the distal phalanx (P3). Ex vivo, experimental study. Ten cadaveric specimens, four forelimbs and six hindlimbs. All cadaveric specimens underwent radiographically guided drilling, followed by cortical screw placement. The cartilage was macroscopically assessed after disarticulation of the distal interphalangeal joint. The entry point and trajectory were evaluated with computed tomography. Results were categorized as: axial, near-axial and abaxial. The minimal distance from the outer margin of the drill hole and the proximal border of the subchondral bone plate was measured using frontal computed tomographic slices. Eight of the 10 screws were in an axial to near-axial position and nine followed the desired axial to near-axial trajectory. One screw was inserted axially but continued in an abaxial trajectory. Iatrogenic damage to the joint cartilage, flexor cortex and solar canal of P3 was not observed. All cortical screws were placed close to the proximal subchondral bone-plate of P3. The desired axial/near-axial drilling and screw placement, under radiographic guidance, was achieved in nine out of 10 specimens. This novel technique seems promising for the treatment of inaccessible P3 cysts. Additional studies are required to investigate its feasibility in clinical cases, and the long-term outcome following transcystic screw placement of type 3 P3 cysts.

Design and experimental analysis of a new vertical ultra-low-head hydro turbine with the variation of outlet flow level on the head drop section of an open canal

Hydropower generation from ultra-low-head water resources is the salient category. The power can be tapped through different non-conventional turbines and is developing these days with different features. This research aims to develop a technology that applies to ultra-low-head resources from conceptualization to laboratory testing. Among several ultra-low-head water resources, it is concentrated on the power generation from the head drop section of the open canal flow through a new hydro turbine. A vertical shaft turbine with an axial flow type of runner having fixed, flat, and constant blade thickness including fixed guide vanes has been designed conventionally for 0.5 m of head and 0.088 m3/s of discharge. Several experiments have been conducted with fixing the level of flow outlet control from 0.0 m to 0.5 m creating the runner from free to submerged conditions is the novelty of this research. The results obtained for all the independent and dependent variables are presented and discussed for a constant flow of 0.088 m3/s and constant speed of 115 rpm conditions. The uncertainty on measurement was found ±1.85 % and the overall maximum efficiency obtained was 53.8 % for flow 10 % above the design flow. The research has concluded the use of outlet flow control is necessary to achieve the maximum efficiency of the turbine at a specific height and the overall efficiency can be advanced further through the optimization of blade profile.

Design and Construction of a 3-Phase Axial Type BLDC Generator for PLTB

The need for electrical energy in remote areas to improve community welfare must be a concern for universities. The government's ability to build new electricity sources is very minimal because it requires large infrastructure and costs, but the government continues to strive to develop new power plants. Therefore, it is necessary to strive for innovation to build power plants from renewable energy sources. There is a need to use renewable energy as an alternative to replace electrical energy which is increasingly in crisis. One alternative energy that is easy to make is energy that uses magnetic force as a model for generating electricity. Brushless Direct Current (BLDC) motors are an alternative to current DC motors. This three-phase permanent magnet axial flux generator is specially designed for vertical-type wind turbines. This generator consists of two stators and one rotor. where each stator consists of 9 coils and the magnet used is a neodymium permanent magnet. Based on test results, this generator can produce a voltage of 12.57 VDC with a wind speed of 6.84 m/s. So, it can turn on DC lights and charge DC batteries. This three-phase axial BLDC generator was tested in 3 stages, namely without load, using battery load, and DC-light load with wind conditions depending on natural conditions.

Investigation on failure mechanism and time-delay fracturing behavior of hard-rock tunnel under extremely high geostress state

To investigate the failure mechanism and time-delay fracturing behavior of hard-rock tunnel under extremely high geostress state, a series of conventional triaxial compression tests and time-delay loading–unloading mechanical tests on rocks were conducted. Combining testing results and on-site data of deep-buried tunnels, the generation mechanism and failure process of time-delay rockbursts were analyzed. The results indicate that with the increase of confining pressure, the failure mode of hard-rock exhibits a transition from axial splitting type and shear-slip type to special squeezing-expansion type. The progressive damage of rocks under extremely high stress state mainly manifests as aging lateral and volumetric expansion. Under time-delay compression tests, the long-term strength of hard-rock is lower than the threshold stress of σeb. In extremely high stress state, the fracture and dissipated energy evolution of rocks has significant time-dependent characteristics. Under extremely high stress conditions, rocks can store a large amount of releasable energy internally and gradually generate numerous cracks without the need for external work, ultimately leading to sudden unstable failure. Affected by the superposition of time-delay pressure and loading–unloading effects, the hard-rock also exhibits the same time-dependent fracturing behavior as soft-rock under high stress state, but its deformation mechanism is dominated by lateral expansion and crack volumetric dilatancy. When the stress level is far from reaching the ultimate strength required for rockmass failure, it is sufficient to cause the propagation of internal microcracks. Under the action of time-delay loads, the spalling and peeling failure of surrounding rock is significantly reduced, but the scale of unstable blocks is larger. Based on the failure process and microseismic monitoring date of rockburst in hard-rock tunnels, the entire evolution process of time-delay rockbursts can be divided into the following six stages: before excavation, rockmss excavation, aging cracking, squeezing-expansion, instability and spalling, time-delay rockburst. Time-delay rockburst has an obvious acoustic emission calm period before its occurrence, making its incubation process has strong suddenness and randomness.

RANCANG BANGUN GENERATOR MAGNET PERMANEN FLUKS AKSIAL PADA PROTOTYPE PEMBANGKIT LISTRIK TENAGA BAYU (PLTB) SUMBU VERTIKAL

Axial flux permanent magnet generators are easy to manufacture because only the rotor and stator are aligned. Axial flux generators are one of the right choices for wind power plants due to the large number of magnetic poles, high electrical power density, and easy-to-increase power capacity. The axial flux type permanent magnet generator is designed with a speed of 600 rpm, a frequency of 50 Hz, a voltage of 12 V, a power of 7 Watts, 1 phase, 10 pairs of Neodymium Iron Boron (NdFeB) type magnetic poles, and 5 copper wire coils measuring 0.6 mm in diameter with a total of 301 turns. This vertical-axis wind farm test uses an axial flux permanent magnet generator with a 5? resistor load and is assisted by a blower. The blower is used to get a constant turbine rotation in accordance with the results of wind speed measurements taken for 3 days on the rooftop of the electrical engineering lecture building, namely the wind speed range of 3-5 m/s. Based on these tests, the generator is able to produce a voltage of 1.5 V, a current of 0.2 A, a power of 0.27 Watt, and a generator efficiency level of 0.63% at a wind speed of 3 m/s. It also produces a voltage of 4.4 V, a current of 0.7 A, a power of 2.77 Watt, and a generator efficiency level of 0.97% at a wind speed of 5 m/s.

PENGARUH VARIABEL CELAH UDARA TERHADAP FLUKS MAGNET PADA GENERATOR PERMANEN MAGNETIK AXIAL FLUKS

Generators that use permanent magnets do not require initial excitation to produce voltage. where the generator design is an axial flux type using a ceramic type permanent magnet (NdFeB), and uses two flanking stator rotors. For electricity use, the AC voltage is changed to DC voltage using a rectifier for charging the accumulator. The air gap in an axialflux generator is the distance between the rotor and stator. The air gap is also a place for the magnetic field to move through the coils in the stator which ultimately produces a magnetic flux value which will influence the amount of induced voltage produced. The faster the rotation produced, the greater the voltage produced, but the frequency value will also increase, so that this generator is only limited to 400 rpm rotation, at a frequency value of 50 Hz, producing an effective voltage of ± 22 V with an air gap distance ( δ) is 2 mm, the frequency measurement has an error of 10-20 Hz and an error percentage of 5-10%, with the results of the induced current measurement having the same voltage

Experimental and numerical comparisons among various skewed blades of low speed axial fan rotors

Literature indicates that there is lack of study related to the effects of axially skewed blades on the aerodynamic performance of axial flow fans. In this study rotors of various blade skews, namely, axial, circumferential and axial-circumferential types, are studied and their aerodynamic performances are compared to those of the baseline radial rotors of two types, namely, constant chord and varying chord. The skew in a blade can be considered as combination of sweep and dihedral. The skew change from the circumferential to axial type causes reversal of dihedral induced radial blade force and hence a reversal of meridional streamline curvature which in turn reverses the modulation of the end-wall loads. The inherent forward sweep in the forward skewed blades also modulates hub and tip loads. Thus, in a forward axial skew blade the forward sweep and positive dihedral combine favorably to unload the tip and to upload the hub. In the forward circumferentially skewed blades, forward sweep and the negative dihedral have mutually countering effects on end-wall load modulation. The highlight of this study is that it has demonstrated experimentally the unloading of the tip in the forward axially skewed blades which resulted in reduced losses and better performance including increased stall margin. Reduced tip loading was also verified from the casing pressure sensor measurements which showed weakening of tip vortex. The relative influence of sweep and dihedral on performance was additionally demonstrated in the axially-circumferentially skewed rotor of the constant chord type, with improvements attributable to higher sweep.

Design optimization of bellow joints used in liquid propellant rocket engines

Abstract Bellow joints are frequently used in hydraulic lines, constructions, and various areas such as nuclear stations to absorb the energy caused by flow and external forces, provide flexibility to the lines, and prevent damages such as cracking and deterioration in the flow lines. There exist various types of bellow joints (e.g., axial type, gimbal type, and hinge type) that allow axial, lateral, and angular movements. Bellow joints that assist thrust vector control in liquid propellant rocket engines prevent the hydraulic lines from being damaged during the orientation movements of the missile. While providing this flexibility to the lines in rocket engines, they create additional force against the linear actuators that move the liquid motor nozzle. This additional force causes the need for larger actuators, resulting in more weight and volume. In this study, design optimization of the bellow joint used in liquid propellant rocket engines is conducted to minimize the force transferred to the actuators by minimizing the bending moment developed in the bellow joint. It is found that the bending moment developed in the bellow joint could be reduced by a significant rate of 75 % without compromising the structural integrity of the bellow joint.

A design study on 20 kW class axial flux motor with HTS field winding for 100 MPa liquid hydrogen pump

This paper presents a design study of a low-speed, high torque 20 kW class motor with a high-temperature superconductor (HTS) field coil for a liquid hydrogen centrifugal pump. The motor is designed based on three key concepts: 1) employing an axial-flux motor topology that can increase torque density by reducing the axial length together with a centrifugal pump; 2) using liquid hydrogen in a pump as a coolant for HTS coil; 3) adopting no-insulation (NI) YBCO solenoid coils as field coils of the motor to improve coil protection as well as mechanical stability. In the design process, first, an electromagnetic design of the axial type motor is obtained considering the required performance of previous commercial pumps. Considering the current and temperature margin to secure the HTS coils' stable operation, two types of HTS coils (solenoid type and triangle type) are designed and their performances are compared. Second, to evaluate validity of the electromagnetic designs, mechanical stresses in the HTS coils are estimated. By comparing the solenoid type and the triangle type, it is confirmed that the solenoid type has a distinct stress-reducing effect in terms of magnetic stress as well as rotational stress. Our design study results show the potential superior performance of the axial flux motor with HTS coils for several tens of kW applications with low speed and high torque loads such as liquid hydrogen pumps.

Design of a 1-phase Axial Flux Type Generator with a Variation of Winding on a Star-Shaped Stator

A single-phase axial flux generator with a star-shaped stator is required to explore the optimal use of rainwater energy as a renewable energy source. Untuk eksperimen, jumlah coils dan diameternya diubah. 25 coils dan 50 coils with 0.4 mm diameter and 25 coils and 40 coils with 0.5 mm diameter were designed. Generator performance will be tested under load and no load conditions at 600 rpm to 2000 rpm. The test results indicate that, for a single-phase axial generator running at 2.4W output conditions, increasing the number of windings impacts the voltage induced by the generator and that the number of stator windings influences the quantity of induced voltage, current, and power. Test findings with various winding variations, employing a 4.8V 0.5A or 2.4W light bulb load, demonstrate that an increase in winding count leads to an increase in electrical output

Distinguishing Amazonian ipê species (Handroanthus, Bignoniaceae) using macroscopic wood anatomy and leaf morphology

Summary The ipê trees belonging to the genus Handroanthus are among the most exploited species in the Amazon Forest. However, limitations in the wood identification processes can lead to an overexploitation of a single species. We compare, macroscopically, the wood anatomy of five Amazon Handroanthus species (H. barbatus, H. capitatus, H. impetiginosus, H. incanus and H. serratifolius–Bignoniaceae). Except for H. barbatus the species are trees over 20 m tall and are used commercially. We compared leaf morphology of the two most commercially used species (H. impetiginosus and H. serratifolius), aiming to separate them in the field with identification keys. For wood macroscopical analyses, 55 samples were used; the specimens were obtained in the field and from wood collections. The dichotomous key, preferable to be used in a laboratory, enables the distinction of the five species. However, the use of this key requires more knowledge about wood anatomy, since it was necessary to use more quantitative characteristics, due to the great intraspecific variation in Handroanthus woods, also reflected in the PCA (principal components analysis) and grouping analysis. To identify the plant species H. impetiginosus and H. serratifolius, the use of axial parenchyma type and vessel characteristics were important distinguishing factors, while in leaves, the most significant features were characteristics such as leaf margin, trichomes and domatia. In addition, by focusing on these key features, a multiple access identification key was created, which simplified the identification by reducing the number of characteristics necessary for the identification, facilitating its use in the field.

Performance prediction of roadheaders used in coal mines from the needle penetration index and the schmidt hammer value

Coal mine galleries and construction tunnels are commonly excavated using roadheaders. Estimating the performance of roadheaders is crucial for planning and cost estimation when planning tunnel or tunnel projects. The aim of this study is to derive generalized performance prediction models including Schmidt hammer value, needle penetration index, and volumetric joint count for roadheaders used in coal mines. The performance measurements of axial and transverse type roadheaders were carried out in six different coal mines. Schmidt hammer tests, needle penetration index tests, and of volumetric joint count measurements were also performed at the locations where the performance measurements were conducted. The extensive data were evaluated using multiple linear and nonlinear regression analysis. The developed formulas were evaluated using statistical tests. The Equations that include the Schmidt hammer value or needle penetration index value in addition to cutter head power have been shown to be unreliable. However, the equations that include Schmidt hammer value or needle penetration index value in addition to cutterhead power and volumetric joint count have been shown to be reliable. This study concludes that the developed reliable equations can be used for the performance assessment of roadheaders used in coal mines.

Numerical Simulations on Combustion and Heat Transfer in Porous Medium with Different Gyroid Triply Periodic Minimal Surfaces Structures

ABSTRACT To investigate the influence of the porous medium with Triply Periodic Minimal Surfaces (TPMS) structures on lower concentration methane combustion. This study analyzed the flow field and heat transfer in the porous medium with three types, i.e. an axial gradual period type, a conical type and a uniform type, through the pore-scale simulation (PSS) approach. In cases of this study, the flashback equivalence ratio of the conical PMB is about 12.5% lower than that of the gradient PMB at the same inlet flow velocity, and the blow-off inlet flow velocity of the conical PMB is about 30% higher than that of the gradient PMB at the same equivalence ratio. Moreover, the flame shape is closely related to the local solid structure and flow velocity. The solid surfaces radiation heat transfer occurred mainly in regions with high solid temperature gradients. Additionally, the absolute value of the radiant heat flux is about 1/4 to 1/5 of the total heat flux, which reflects the proportion of thermal convection in the heat transfer on the solid surface. Convective heat transfer between solid and fluid occurred mainly in the areas of heat recuperation known as preheat zone, and higher inlet flow rates significantly increase the upstream convective heat transfer intensity.