Lateral Field Research Articles

Comparing film measurements and Monte Carlo simulations of dose delivered in a pelvic phantom with titanium hip prosthesis

An increasing number of elderly prostate cancer patients with high-density material hip prostheses are referred for external beam Radiotherapy (EBRT). Radiation treatment of pelvis cancer patients with high-density hip prostheses needs special attention due to the artifacts created in the computed tomography (CT) field of view and the radiotherapy dosimetry challenges. This study investigated the pelvic prostate point dose with and without titanium hip prosthesis using a 0.6 cc PTW Farmer ionization chamber, EBT3 Gafchromic films, compared with the EGSnrc Monte Carlo (MC) simulation dose distribution. The doses were measured and simulated in a locally made pelvic phantom. MC and measured doses were compared with the Treatment Planning System (TPS) calculated prostate point dose. The ionization chamber, EBT3 Gafchromic films, and MC doses have a maximum deviation of 6.3 %, 5.7 %, and 7.4 % for 6 MV and 4.2 %, 4.7 %, and 5.5 % for 15 MV photon beam, respectively, when compared with TPS calculated dose. There is a significant difference between the prostate point dose measured with ionization chamber, EBT3 Gafchromic film in comparison MC simulated doses. The MC simulation dose shows the highest deviation especially on the lateral field passing through the prosthesis.

Deladenus taedae n. sp. (Nematoda: Neotylenchidae) in Loblolly pine (Pinus taeda) woods from USA intercepted in Ningbo, P.R. China

Summary Deladenus taedae n. sp. was isolated from loblolly pine wood (Pinus taeda) intercepted in Ningbo, P.R. China, in imports from the USA. This new species is morphologically described and illustrated and characterised molecularly. Both mycetophagous and infective forms were recovered and described. The new species, D. taedae n. sp., resembles some other species of Deladenus in which the excretory pore is situated anterior to the hemizonid. The new species is characterised by the lateral fields with six lines, pointed tail ending and small spermatheca in mycetophagous females and short stylet in infective females. In mycetophagous females, the excretory pore is 74-98 μm from the anterior end and 37-54 μm anterior to the hemizonid. The partial rDNA 18S, complete internal transcribed spacer, 5.8S and partial 28S D2/D3 genes were amplified and sequenced. Phylogenetic analyses of the genes distinguished this new species from all other sequenced Deladenus species.

Visible to Short‐Wave Infrared Broadband p‐WSe2/n‐Ge Heterojunction Phototransistor with an Annular Shallow‐Trench Schottky Barrier Collector

Van der Waals (vdW) heterostructures based on two‐dimensional materials and conventional group IV semiconductors have shown great potential for wide spectrum, highly sensitive photodetectors owing to their broadband absorption, high‐quality interface, and compatibility with complementary metal‐oxide‐semiconductor (CMOS) technology. Herein, a unique heterojunction phototransistor composed of an indium tin oxide capped p‐WSe2/n‐Ge vdW heterojunction serving as the emitter and an annular shallow‐trench Al/Ge Schottky junction acting as the collector is proposed. The mixed‐dimensional phototransistor exhibiting high responsivities up to 66 A W−1 at 405 nm and 124 A W−1 at 1,550 nm demonstrates a brilliant wide spectrum response performance. The high photocurrent gain can be attributed to the extra‐large carrier injection ratio of the heterojunction. The short transient response time in the order of 100 μs is achieved with the modified lateral electrical field by the annular shallow‐trench Schottky barrier collector. The combination of p‐WSe2/n‐Ge vdW heterojunction and the annular shallow‐trench Al/n‐Ge Schottky junction renders a low‐cost, high‐performance photodetector fabricated in a simple and CMOS compatible way for visible to short‐wave infrared broadband detection.

Nanograded artificial nacre with efficient energy dissipation

The renowned mechanical performance of biological ceramics can be attributed to their hierarchical structures, wherein structural features at the nanoscale play a crucial role. However, nanoscale features, such as nanogradients, have rarely been incorporated in biomimetic ceramics because of the challenges in simultaneously controlling the material structure at multiple length scales. Here, we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite platelets through a matrix-directed mineralization method. The gradients are formed via the spontaneous accumulation of graphene oxide nanosheets on the surface of the platelets during the mineralization process, which then induces a lateral residual stress field in the platelets. Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsically through the compressive stress near the platelet surface. The energy dissipation density reaches 0.159± 0.007 nJ/μm3, and the toughness amplification is superior to that of the most advanced ceramics. Numerical simulations also agree with the finding that the stress field notably contributes to the overall energy dissipation. This work demonstrates that the energy dissipation of biomimetic ceramics can be further increased by integrating design principles spanning multiple scales. This strategy can be readily extended to the combinations of other structural models for the design and fabrication of structural ceramics with customized and optimized performance.

Simulation of Head-on Collisions between Filamentary Molecular Clouds Threaded by a Lateral Magnetic Field and Subsequent Evolution

Filamentary molecular clouds are regarded as the place where newborn stars form. In particular, a hub region, a place where it appears as if several filaments are colliding, often indicates active star formation. To understand the star formation in filament structures, we investigate the collisions between two filaments using two-dimensional magnetohydrodynamical simulations. As a model of filaments, we assume that the filaments are in magnetohydrostatic equilibrium under a global magnetic field perpendicular to the filament axis. We set two identical filaments with an infinite length and make them collide with a zero-impact parameter (head-on). When the two filaments collide while sharing the same magnetic flux, we found two types of evolution after a merged filament is formed: runaway radial collapse and stable oscillation with a finite amplitude. The condition for the radial collapse is independent of the collision velocity and is given by the total line mass of the two filaments exceeding the magnetically critical line mass for which no magnetohydrostatic solution exists. The radial collapse proceeds in a self-similar manner, resulting in a unique distribution irrespective of the various initial line masses of the filament, as the collapse progresses. When the total line mass is less massive than the magnetically critical line mass, the merged filament oscillates, and the density distribution is well-fitted by a magnetohydrostatic equilibrium solution. The condition necessary for the radial collapse is also applicable to the collision whose direction is perpendicular to the global magnetic field.

(Invited) Visualization of Charge Density Distribution in Parallel-Plate Dielectric Barrier Discharge Under Atmospheric-Pressure Air

Dielectric barrier discharge (DBD) is one of the atmospheric nonequilibrium plasma and is typically driven by sinusoidal or pulse voltage with electrodes that dielectric is inserted. DBD has been used in some industries such as plasma medicine and material processing. However, the fundamental process of DBD has not been elucidated yet. When a parallel plate DBD is driven by sinusoidal voltage under atmospheric pressure, numerous filamentary discharges called microdischarges (MDs) are observed. The surface charge deposited on the dielectric after the discharge plays a major role in the behavior of these MDs. As the MD develops during the gap and reaches the dielectric surface, a surface discharge occurs and deposits the charge on the dielectric surface.We performed dielectric surface charge measurements using Bi4Ge3O12, a Pockels crystal, in a short-gap, parallel-plate DBD of 0.5 and 0.3 mm driven by a sinusoidal high voltage. The high-speed camera enabled measurement of the spatio-temporal distribution of surface charge and estimation of the net electric field and the characteristics of microdischarges (MDs).The net electric field strength in the gap was estimated from the measurement results. The axial reduced electric field strength generated by the surface charge was found to be equivalent to 50-60% of the peak value of the applied electric field with all the voltage amplitude and gap length in this study, and the gap electric field after discharge was suppressed to less than 100 Td. Such a strong field keeps the MDs in a nonequilibrium plasma and also prevents re-discharge in the same position at the half cycle. On the other hand, the lateral electric field strength generated by the surface charge is largely characterized by the charge distribution—i.e., the voltage amplitude, gap length, and charge polarity—as mentioned above. Higher amplitude of applied voltage leads to an increase in the area of high lateral electric field strength above 100 Td. Compared to the gap length of 0.5 mm, the lateral electric field weakened, while the axial electric field generated by the surface charge was stronger in the gap length of 0.3 mm. As for the relationship between the charge polarity and the lateral electric field, the lateral field at the anodic dielectric, which the negative charge is deposited on, is dominant in the region of less than 100 Td. Meanwhile, on the cathodic dielectric, which the positive charge is deposited on, the area of above 100 Td is larger. That is, the strong lateral electric field can be observed near the cathodic dielectric, rather than the anodic dielectric. Thus, different chemical reactions may occur in the vicinity of the anodic and cathodic dielectrics, respectively, because of the difference in the drifting charged particles and the lateral field strength.

Prompt Pain Relief From Bone Metastases: The Virtual Simulation Program

Rapid pain relief for patients with bone metastases can be a challenge due to the lengthy and complex radiation therapy workflow. The purpose of this study was to evaluate the time (in days) between initial radiation oncology consultation and start of palliative radiation treatment after implementing an alternative virtual simulation palliative workflow. Patients meeting strict criteria were selected for virtual simulation, which included only those with painful bone metastases who were recommended palliative radiation therapy using standard anterior-posterior/posterior-anterior or opposed lateral fields. A recent (within 30 days) diagnostic computed tomography (CT) scan clearly visualizing the target volume was required for treatment planning. For comparison, a reference group of 40 consecutive patients with bone metastases who underwent in-person CT simulation before virtual simulation implementation was reviewed. Forty-five patients were treated for painful bone metastases as part of the virtual simulation program from May 2021 to October 2022. Regarding travel distance, 23 patients lived locally (<50 miles from the treatment center) and 22 patients were distant (≥50 miles from the treatment center). Average time from consultation to treatment for all patients undergoing virtual simulation was 3.7 days, compared with 7.5 days for patients undergoing in-person CT simulation (3.8 days sooner, on average; P ≤ .001). Before full implementation of the virtual simulation program, 5 eligible patients participated in a virtual simulation pilot from April 2021 to May 2021, in which each patient was contoured and planned on both a pre-existing diagnostic CT scan and a standard CT simulation scan. For virtual simulation-based plans, the average V90, V95, and V99 were 99.99%, 99.87%, and 96.70%. No significant planning target volume (PTV) coverage difference was found on subsequent in-person CT simulation scans. The virtual simulation program decreased the time from consultation to start of treatment by more than 50% for patients recommended palliative radiation therapy for painful bone metastases. This benefit was most significant for outpatients traveling ≥50 miles for treatment. Virtual simulation-based planning can be considered for patients anxious to proceed with radiation therapy quickly or in underserved settings with limited transportation options to regional treatment centers.

Research on dual lateral log simulation of shale bedding fractures under different influencing conditions

Micro scale fractures play a crucial role in facilitating the migration of oil and gas in low permeability shale reservoirs. However, the identification of such fractures is a complex task. The efficacy of the dual lateral log physical field changes as a means of identifying shale micro fractures remains uncertain. To address this issue, a three-layer shale bedding fracture model was developed using the finite element method and core and conventional logging data from eight wells, which was based on different shale reservoirs within the Yanchang Formation in the Ordos Basin. The present study examines the dual lateral log response characteristics resulting from distinct characteristics of horizontal bedding fractures, with a focus on the response mechanism. The simulation of logging response characteristics of shale and siltstone combination were utilized by core statistical data for verification purposes. The results indicate that under the lithology combination of shale and siltstone, the magnitude of the difference between the resistivity of the filled fracture and the formation resistivity, the greater the formation resistivity of the shale itself, the wider the fracture width, and the greater the difference between the apparent resistivity and the real formation resistivity. Furthermore, the suitable conditions for the detection of shale bedding fracture characteristics by dual lateral log are clarified. In the presence of effective filling, the dual lateral log has the capability to identify shale fractures at the micron scale. The findings of our study establish a theoretical framework for the identification and assessment of shale fractures, and furnish technical assistance for the optimal selection of “sweet spots” within shale reservoirs and the precise evaluation of reservoirs. This study lays a theoretical foundation for the identification and evaluation of shale fractures, and provides technical support for the optimal “sweet spot” selection of shale reservoirs and the accurate evaluation of reservoirs.

Implantation site design for large area diamond quantum device fabrication

With the number of qubits increasing with each new quantum processor design, it is to be expected that the area of the future quantum devices will become larger. As diamond is one of the promising materials for solid state quantum devices fabricated by ion implantation, we developed a single board diamond detector/preamplifier implantation system to serve as a testbed for implantation sites of different areas and geometry. We determined that for simple circular openings in a detector electrode, the uniformity of detection of the impinging ions increases as the area of the sites decreases. By altering the implantation site design and introducing lateral electric field, we were able to increase the area of the implantation site by an order of magnitude, without decreasing the detection uniformity. Successful detection of 140 keV copper ions that penetrate on average under 100 nm was demonstrated, over the 800 µm2 area implantation site (large enough to accommodate over 2 × 105 possible qubits), with 100% detection efficiency. The readout electronics of the implantation system were calibrated by a referent 241Am gamma source, achieving an equivalent noise charge value of 48 electrons, at room temperature, less than 1% of the energy of impinging ions.

Description of Devibursaphelencus lordeganensis sp. n. (Ektaphelenchinae) from Iran

Summary A population of the genus Devibursaphelenchus was collected from the inner part of the decaying Persian oak tree (Quercus brantii) from Lordegan city of Chaharmahal va Bakhtiari Province, Iran. The morphological and molecular characters confirmed the new species, namely D. lordeganensis sp. n. The new species is characterised by female body length (768-1026 μm), lip region separated from the rest of the body by a slight constriction, obscure lines on lateral fields, stylet length long, slender, wide-lumened, tripartite, composed of a conus with an aperture about half its length, a conophore about equal with the conus, and a shaft, taller than (conus + conophore) length, lacking basal knobs or swelling, excretory pore ca three metacorpal lengths posterior to the base of the metacorpus, post-uterine sac (PUS) (36-67 μm long; 1.3-3.7 times longer than vulval body diam.), absence or vestigial of rectum and anus, posterior end of the body conical with a rounded tip (in some specimens with a spherical protruded projection at tail tip), males 668 to 815 μm long, presence of two pairs of caudal papillae (P2 and P3), spicule length (15-17 μm) with long and wide bladed condylus, triangular rostrum with a blunt tip and small bursa flap ending at the tail tip. The molecular phylogeny based on 28S rDNA revealed that the new species stands close to D. alienae (LC629160) and D. lini (FJ768944, AM396570). The measurements, line illustrations, light microscopy photographs and phylogenetic analysis are given for the new species. In addition, a key to the species of Devibursaphelenchus is given.

Distributions of Visual Receptive Fields from Retinotopic to Craniotopic Coordinates in the Lateral Intraparietal Area and Frontal Eye Fields of the Macaque

Even though retinal images of objects change their locations following each eye movement, we perceive a stable and continuous world. One possible mechanism by which the brain achieves such visual stability is to construct a craniotopic coordinate by integrating retinal and extraretinal information. There have been several proposals on how this may be done, including eye-position modulation (gain fields) of retinotopic receptive fields (RFs) and craniotopic RFs. In the present study, we investigated coordinate systems used by RFs in the lateral intraparietal (LIP) cortex and frontal eye fields (FEF) and compared the two areas. We mapped the two-dimensional RFs of neurons in detail under two eye fixations and analyzed how the RF of a given neuron changes with eye position to determine its coordinate representation. The same recording and analysis procedures were applied to the two brain areas. We found that, in both areas, RFs were distributed from retinotopic to craniotopic representations. There was no significant difference between the distributions in the LIP and FEF. Only a small fraction of neurons was fully craniotopic, whereas most neurons were between the retinotopic and craniotopic representations. The distributions were strongly biased toward the retinotopic side but with significant craniotopic shifts. These results suggest that there is only weak evidence for craniotopic RFs in the LIP and FEF, and that transformation from retinotopic to craniotopic coordinates in these areas must rely on other factors such as gain fields.

Bottom Contact 100nm Channel-Length α-In2 Se3 In-Plane Ferroelectric Memory.

Owing to the emerging trend of non-volatile memory and data-centric computing, the demand for more functional materials and efficient device architecture at the nanoscale is becoming stringent. To date, 2D ferroelectrics are cultivated as channel materials in field-effect transistors for their retentive and switchable dipoles and flexibility to be compacted into diverse structures and integration for intensive production. This study demonstrates the in-plane (IP) ferroelectric memory effect of a 100nm channel-length 2D ferroelectric semiconductor α-In2 Se3 stamped onto nanogap electrodes on Si/SiO2 under a lateral electric field. As α-In2 Se3 forms the bottom contact of the nanogap electrodes, a large memory window of 13V at drain voltage between ±6.5V and the on/off ratio reaching 103 can be explained by controlled IP polarization. Furthermore, the memory effect is modulated by the bottom gate voltage of the Si substrate due to the intercorrelation between IP and out-of-plane (OOP) polarization. The non-volatile memory characteristics including stable retention lasting 17 h, and endurance over 1200 cycles suggest a wide range of memory applications utilizing the lateral bottom contact structure.

A novel high-performance trench lateral double-diffused MOSFET with buried oxide bump layer

A shallow-trenched Lateral Double-Diffused MOSFET with folded drift region (FD LDMOS) is proposed in this paper. The new structure divides the drift region into two parts. The left side is introduced in a shallow trench, and the right side is used to take advantage of the buried oxide bump layer. The new structure optimizes the lateral and vertical electric fields simultaneously. The self-adaptation of the drift region improves the doping concentration (Ndd), reducing specific on-resistance (Ron,sp) and parasitic capacitance. The simulation results show that compared with the conventional LDMOS (Con. LDMOS), the breakdown voltage (BV) has increased by 53%, and the figure of merit (FOM) has increased by 173.4%; the power-added efficiency (PAE) near the P3dB operating point is increased from 44.43% to 63.67% at the frequency of 1.2 GHz.

Mosaicing Technology for Airborne Wide Field-of-View Infrared Image

Multi-detector parallel scanning is derived from the traditional airborne panorama camera, and it has a great lateral field of view. A wide field-of-view camera can be used to obtain an area of remote sensing image by whisk broom mood during the flight. The adjacent image during acquisition should cover the overlap region according to the flight path, and then the regional image can be generated by image processing. Complexity and difficulty are increased during the regional image processing due to some interference factors of aircraft in flight. The overlap of the acquired regional image is constantly variable. Depending on the analysis of the imaging geometric principle of a wide field-of-view scanning camera, this paper proposes the rigorous geometric model of geoposition. The infrared image mosaic technology is proposed according to the features of regional images through the SIFT (Scale Invariant Feature Transform) operator to extract the two best-matching point pairs in the adjacent overlap region. We realize the coarse registration of adjacent images according to image translation, rotation, and a scale model of image geometric transformation, and then the local fine stitching is realized using the normalized cross-correlation matching strategy. The regional mosaic experiment of aerial multi-detector parallel scanning infrared image is processed to verify the feasibility and efficiency of the proposed algorithm.

Aphelenchoides tenuis n. sp. (Tylenchina: Aphelenchoididae) found in loblolly pine logs imported from the USA

Summary Aphelenchoides tenuis n. sp. found in loblolly pine (Pinus taeda L.) logs imported from the USA, is described. It is characterised by a very slim body (a = 56.8 (45.8-67.2) and 49.1 (42.2-54.2) in males and females, respectively), three incisures in the lateral field, short stylet (9-12 μm), the excretory pore located at the level of nerve ring, the vagina is not sclerotised, the vulva has slightly protruding lips and lacks a flap and the post-uterine sac is well developed, forming ca 36.2 (28.4-48.2)% of the vulva to anus distance. The spicules are smoothly arcuate, the apex and rostrum are rounded and well developed, and the dorsal limb is 23.3 (21.1-25.5) μm long, without a hook-like structure at the distal tip. The male tail bears three pairs (2 + 2 + 2) of caudal papillae. The tail of both sexes is sub-cylindrical, the terminus bearing a bluntly pointed mucron with tiny nodular protuberances. The new species belongs to the Group 2 category of Aphelenchoides species sensu Shahina and is defined as A2-B1/2-C1-D1/2-E2-F2/3 according to the categorisation codes of OEPP/EPPO. Phylogenetic analysis based on 18S and 28S D2-D3 of rDNA, along with ITS and mtCOI, confirmed its status as a new species.

First Report of Heterodera zeae Koshy, Swarup & Sethi, 1971 (corn cyst Nematode) Infecting Corn (Zea mays) in Spain.

Heterodera zeae Koshy, Swarup & Sethi, 1971 (corn cyst nematode) is an important disease of corn in several areas of the world, including India, Nepal, Pakistan, Egypt, USA, Greece and Portugal (Subbotin et al., 2010). It is a sedentary semi-endoparasite feeding on corn roots and other Poaceae plants and has been associated with significant yield losses in corn (Subbotin et al., 2010). During autumn 2022 a plant-parasitic nematode survey performed in corn at central-western area of Spain (Talavera de la Reina, Toledo), revealed a commercial field with stunted plants. Nematodes were extracted from soil by centrifugal-flotation method (Coolen, 1979). Corn roots inspection detected infections by immature and mature cysts, and soil revealed also mature live cysts and second-stage juveniles (J2s) with a population density of 1010 eggs and J2s/500 cm3 soil (including eggs from cysts). J2s and cysts were processed to pure glycerine using De Grisse's (1969) method. DNA was isolated from single live fresh J2s specimens for amplifying and sequencing of cytochrome c oxidase subunit II (COII) mitochondrial region using the primer pair species-specific H.Gly-COIIF_inFOR/P116F-1R (Riepsamen et al., 2011); D2 and D3 expansion domains of the 28S rRNA were amplified using the D2A/D3B primers (De Ley et al. 1999); internal transcribed spacer (ITS) region using primers TW81/AB28 (Subbotin et al., 2001); and cytochrome c oxidase subunit 1 (COI) gene was amplified using the primers JB3/JB5 (Bowles et al., 1992). Brown cysts were lemon-shaped with a protruding vulval cone with fenestra ambifenestrate, bullae prominent below underbridge and characteristically arranged in finger-like bullae (Fig. 1). J2 with slightly offset lip region (3-5 annuli), stylet strong with rounded stylet knobs, lateral field with four lines, and tail short and tapering conically. Measurements of cysts (n=10) included body length 559 (432-688) µm, body width 450 (340-522) µm, fenestral length 40 (36-43) µm, semifenestral width 19 (17-21) µm, and vulval slit 40 (35-44) µm. J2 measurements (n=10) included body length 477 (420-536) µm, stylet length 21 (20-22) µm, tail length 51 (47-56) µm, and tail hyaline region 23 (20-26) µm. Morphology and morphometrics of cysts and J2, fit with original description and others from several countries (Subbotin et al., 2010). Two J2s individuals were sequenced for COII region (OQ509010-OQ509011) showing 97.1-98.1% similarity with H. zeae from USA (HM462012). Six almost identical 28S rRNA sequences from J2s (OQ449649-OQ449654) were 99.2-99.4% similar to 28S rRNA sequences of H. zeae from Greece, Afghanistan and USA (GU145612, JN583885, DQ328695). Four identical ITS DNA fragments from J2s (OQ449655-OQ449658) were 97.0-97.8% similar to ITS sequences of H. zeae from Greece, and China (GU145616, MW785771, OP692770). Finally, six COI sequences of 400 bp obtained for J2s (OQ449699-OQ449704) were under 87% similarity to several COI sequences of Heterodera spp. in NCBI, being a new molecular barcoding for identifying this species. On the basis of these results, the cyst nematodes isolated from the corn plants from the central-western area of Spain (Talavera de la Reina, Toledo) were confirmed as H. zeae and up to our knowledge it is the first report in Spain. This is a well-known pest of corn, causing important losses in this crop (Subbotin et al., 2010) and it was previously regulated as a quarantine nematode in the Mediterranean region (EPPO).

Numerical simulation of lateral jet interaction with rarefied hypersonic flow over a two-dimensional blunt body

Reaction Control System (RCS) is a direct force control system that successfully adjusts a craft's attitude or orbit using the reaction force created by jet flow. RCS is frequently employed in the management of near-space vehicles due to its properties of fast response time and effective control efficiency. When the near-space vehicle is navigating at high altitude in a low density atmosphere, the Navier–Stokes equation is no longer applicable. The numerical approach utilized in this study is known as the Conserved Discrete Unified Gas Kinetic Scheme, and the governing equation is the Boltzmann equation, which is not constrained by the continuum hypothesis. In velocity space, an unstructured mesh is utilized, which minimizes the amount of discrete velocity points and considerably increases computation efficiency. The numerical results are in good agreement with the direct simulation Monte Carlo code DS2V when modeling large Knudsen number lateral jet flow. The interaction flow field between hypersonic free stream and lateral jet is then simulated at altitudes of 60–90 km using argon as the working gas and a two-dimensional blunt cone with lateral jet as the study object. Under a fixed jet pressure ratio, preliminary research was conducted on the variation of the lateral jet interference flow field characteristics with the freestream Knudsen number and angle of attack. The differences in surface pressure and heat flux caused by jet opening and shutting are compared. Under rarefied atmospheric conditions, the variation of the force/moment amplification coefficient is given. The numerical results show that when the angle of attack is 0°, the separation area in front of the nozzle and a pair of opposite vortices, which are common in the jet interference flow field, gradually disappear with increasing altitude, but the separation vortex reappears when the angle of attack of the freestream is increased. The high-pressure region generated upstream of the nozzle is the primary cause of the extra force/moment. The density of the main flow decreases as altitude increases, various shock wave patterns of the interference flow field gradually dissipate and the force/moment amplification factor changes considerably. The rarefied gas effect has a significant effect on the lateral jet interference flow.

SHCT: segmented helical computed tomography based on multiple slant source-translation.

Micro-computed tomography (Micro-CT) is inevitably required to inspect long large objects with high resolution. It is well known that helical CT solves the so-called "long object" problem, but it requires that the measured object be strictly located in the lateral field of view (FOV). Therefore, developing a novel scanning method to extend the FOV in both the lateral and axial directions (i.e., the large helical FOV) is necessary. Recently, due to the application of linearly distributed source arrays and the characteristics of easy extension of the FOV and engineering implementation, straight-line scanning systems have attracted much attention. In this paper, we propose a segmented helical computed tomography (SHCT) based on multiple slant source-translation. SHCT can readily extend the helical FOV by adjusting the source slant translation (SST) length, pitch (or elevation of the SST trajectory), and number of scanning circles. In SHCT, each projection view is truncated laterally and axially, but the projection data set within the cylindrical FOV region is complete. To ensure reconstruction efficiency and avoid the lateral truncation, we propose a generalized backprojection-filtration (G-BPF) algorithm for SHCT approximate reconstruction. Experimental results verify the effectiveness of the proposed SHCT methods for imaging large and long objects. As the pitch decreases, the proposed SHCT methods can reconstruct competitive, high-quality volumes.

Influence of the Lateral Electrostatic Field on the Statistical Distribution of Charge Carriers in a Cylindrical Nanolayer of β-HgS

Analytical expressions are obtained for the wave functions and the energy spectrum of charge carriers in the β-HgS nanolayer of a cylindrical core/shell/shell β-CdS/ β-HgS/ β-CdS nanocomposite in the presence of a strong lateral uniform electrostatic field. It is shown that, under the influence of an external field, the position of the chemical potential of the electron-hole subsystem at absolute zero shifts to the bottom of the conduction band of the sample. The displacement value is determined by the intensity of the external field and increases linearly with increasing field. The concentration, internal energy, and heat capacity of the electronic subsystem of the β-HgS layer in the presence of a field are compared with similar values in the absence of a field. Calculations show that under identical conditions, the presence of an external field leads to an increase in the carrier concentration, which in turn leads to an increase in the internal energy and heat capacity of the system of electrons and holes in the layer.

The Effect of Chemical Reaction on an Unsteady MHD Free Convective Flow Through Porous Medium with Hall Current

In this paper we investigate the effects of Chemical Reaction, Hall currents, Soret and Dufour on unsteady MHD free convective flow through porous medium in the presence of a magnetic field and first order chemical reaction. The similarity solutions were obtained using suitable transformations and the resulting similarity ordinary differential equations were solved by finite difference method. A parametric study illustrating the influence of different flow parameters on velocity, temperature and concentration fields are investigated. The skin frictions at the plate due to tangential and lateral velocity fields are obtained in non-dimensional form. The effects of the various physical parameters on these fields are discussed with help of tables and graphs.