Spiral Form Research Articles

Anatomical studies on the leaf and stem of Tinospora formanii Udayan & Pradeep (Menispermaceae), an endemic species to Southern Western Ghats, Kerala, India

The anatomical studies on leaf and stem of T. formanii Udayan & Pradeep an endemic species to southern Western Ghats, Kerala, India was carried out focusing on its macroscopic, microscopic, maceration along with organoleptic evaluation. Distinguishing characters of the stem revealed the presence of calcium oxalate crystals, simple and compound starch grains and pitted lignified fibers. Leaf anatomy showed the anomocytic and paracytic stomata, pitted lignified fibers, spiral vessels, non-glandular small trichomes, C or half-moon shaped vascular bundle, surrounded with sclerenchymatous tissues and rosette and prism shaped calcium oxalate crystals. Whereas, maceration studies revealed the presence of spiral and scalar form vessel, fibers, calcium oxalate crystals, simple starch grains. These anatomical studies are vital in the present-day trade scenario not only helpful in the proper identification of the genuine materials in use but also to distinguish different species of Tinospora, where the stem and leaf are often admixed with other species of Tinospora in the crude drug markets.

Experimental energy improvement of a special design heat exchanger-based hybrid solar collector for a photovoltaic module square surface.

Solar cells convert a part of the solar irradiance into electrical energy, and the remaining produces heat, which can be converted as a thermal energy accumulated in the module. This conversion depends on the solar cells temperature. Since conversion efficiency is very low, 5-20%, this investigation proposes an optimal combination of a photovoltaic module with a specially designed heat exchanger in order to improve the conversion energy efficiency. So, an experimental prototype of a photovoltaic thermal collector, with a special heat exchanger design for a PV module square surface is built and tested outdoor. The system is constituted of a PV module with square surface and a heat exchanger with a copper tube, in a spiral form. In order to assess the effect of the exchanger design on hybrid system performance, a comparison with a traditional photovoltaic module is done. During the experimental tests, various parameters were measured, such as solar irradiance, ambient temperature, coolant inlet/outlet temperature and surface temperature of the device. Based on the obtained results, it has been found that the use of the new PVT decreases the PV cells temperature in the order of 20°C. A consequence of that shows that the electrical power increases, by 6 W; moreover, the electrical energy efficiency goes from 7.93 to 9.65%, while the thermal energy efficiency of the PVT reaches 74.3%. The overall energy efficiency for the same system achieved was 84 %. Therefore, the energy loss is minimized, reaching 16%.

Unusual clinical manifestation and challenging serological interpretation of syphilis: insights from a case report

BackgroundThe clinical manifestations of recent syphilis can be variable, with typical and atypical patterns. Several conditions may cause atypical clinical aspects, including human immunodeficiency virus (HIV) co-infection. Besides the clinical features, co-infections may completely alter syphilis serological tests, causing interpretative difficulties and diagnostic delays. Aim of the work is to describe the difficulties encountered during the diagnostic evaluation of atypical skin manifestations and of the serology for syphilis of an HIV-infected patient who had contracted it several times.Case presentationIn 2020, a 52-year old HIV-positive bisexual male patient was admitted to our department with a 4-month history of moderately itchy cutaneous lesions localized at his neck, trunk and arms. In 2013, the patient presented with a classic syphilitic roseola of the trunk and a secondary syphilis was diagnosed, with increased levels of rapid plasma reagin (RPR), Treponema pallidum hemagglutination assay (TPHA), anti-Treponema pallidum IgM and IgG Index. A second episode occurred in 2018, as a primary syphilis with multiple ulcerative lesions of the penis, and increased levels of RPR, IgG and IgM. In 2019, a further episode of secondary syphilis was treated with Doxycycline. In 2020, erythematous and papular lesions with vesicular components and urticarial erythema multiforme (EM)-like lesions were present at the neck, trunk and arms. Serological tests and Nucleic Acid Amplification Test (NAAT) for Treponema Pallidum were performed, as well as a cutaneous biopsy with histological and immunohistochemical evaluation of one lesion. NAAT was negative for T. pallidum. Serological test results were discordant with a new syphilis infection, showing only increased levels of RPR and anti-Treponema IgG. The cutaneous biopsy revealed a non specific histological pattern, while the immunohistochemical evaluation with anti-spirochetal antibodies was mandatory for the diagnosis of recent syphilis, showing clusters of rod-shaped elements, some of which with spiral form, focally present at the epidermis and adnexal structures.ConclusionsNowadays, syphilis may present with atypical clinical and serological features. Physicians should be aware of these possible alterations and consider syphilis even in case of uncommon clinical aspect and unclear serological tests. Cutaneous biopsy and immunohistochemical exam may be mandatory for the diagnosis.

Experimental Study of the Flow Structure Stability on the Bubble Surface

The results of the flow structure visualization experiments conducted on the surface of a single bubble streamlined by uniform flow are presented. It is shown that, at certain critical values for bubble size, flow velocity, and contamination level, the axial symmetry of the surface flow loses its stability in a threshold manner, and the first instability mode in the form of two vortices appears. Below the threshold, the stationary flow on the bubble surface is impossible. The experimental results indicate that the assumption about the axial symmetry of the motion on the bubble surface containing surfactants, which is used in most theoretical and numerical studies, is invalid. Analysis of the results has revealed the most likely reason for the spiral form of the trajectory in the problem of a small rising bubble in the surrounding fluid. For the surfactant-free surface realized in the experiments with isopropyl alcohol, the rising trajectory was a straight line, and no vortex structures were observed on the bubble surface. In the experiments with water, a spiral rising trajectory was observed, and the first instability mode was formed on the bubble surface.

Reconfigurable spiral underwater sound-absorbing metasurfaces

A well-designed coiled metasurface can be applied to obtain extraordinary underwater sound isolation. In this letter, we propose a quasi-perfect sound-absorbing metasurface in spiral shape form. This spiral metasurface(SM) meets the two conditions for perfect absorption, which are no transmission at the outlet and no reflection at the inlet. The sound-absorbing characteristics of the SM are investigated through numerical simulation. The simulation results show that the peak frequency of prefect sound absorption can be tuned flexibly over the spectrum, which depends on the design of the parameters. The frequency-controllable SM has quasi-prefect sound absorption coefficient(up to almost 0.998).

Dissulfurispira thermophila gen. nov., sp. nov., a thermophilic chemolithoautotroph growing by sulfur disproportionation, and proposal of novel taxa in the phylum Nitrospirota to reclassify the genus Thermodesulfovibrio

Recently, presence of sulfur-disproportionating bacterial species belonging to the phylum Nitrospirota was indicated by an enrichment culture-based study. In the present study, a strain representing that species was isolated and characterized. The strain, strain T55JT, was isolated from a microbial mat of a hot spring. The cells were motile, and rods or spiral forms with width of 0.32–0.49 μm. The strain grew autotrophically, only by disproportionation of thiosulfate or elemental sulfur. Growth was observed at a temperature range of 25–60°C, with optimum growth at 53–57°C. The pH range for growth was 5.5–9.0, with optimum pH of 7.0–8.0. The complete genome of strain T55JT is composed of a circular chromosome (2,370,875 bp), with G+C content of 38.7%. Thermodesulfovibrio hydrogeniphilus Hdr5T showed the highest sequence similarity of the 16S rRNA gene to strain T55JT, but it was only 88.2%. On the basis of the phylogenetic and physiologic properties, strain T55JT (= DSM 110365T=NBRC 114245T) is proposed as type strain of a novel species in a new genus, Dissulfurispira thermophila gen. nov., sp. nov. To assign the new genus to family and higher taxa, its taxonomic position was assessed by genome-based phylogeny. As a result, it was shown that the novel genus and Thermodesulfovibrio belong to different families. It was also shown that Thermodesulfovibrio should be reclassified at levels from class to family and creation of some novel taxa is required. Based on these results, Thermodesulfovibrionia class. nov., Thermodesulfovibrionales ord. nov., Thermodesulfovibrionaceae fam. nov., and Dissulfurispiraceae fam. nov. are proposed.

Seismic review of spiral façade building collated by rotated cantilever beam

Exposing building façade has led to a magnificent look of the whole building structure creating the assumption of a complicated building structure. Spiral and free form building shape deliver the volatility of the design process not only because of static loading but also dynamic loading such as an earthquake. Modifying an octagon building core throughout its façade by applying an extension cantilever beams and rotating them is the main approach served in this paper establishing a spiral high-rise building. The angle of rotation is varied from 0 to 5 degrees per floor in order to see the stability of the building structure under dynamic loading. The length of the cantilever beam is restrained up to 9 m with the rotating path of an ellipse. The greater the rotation angle, the extreme cantilever beam length in some points. The displacement represents various unpredictable result as the rotation angle livened up as 2-degree and 3-degree rotation angle provides worst. Even though the spiral shape is enormous, the cantilever beam capacity grows critically particularly due to the torsion. Furthermore, reinforcement for the cantilever part must be well confined in order to increase the performance.

Formalized description and synthesis of schemes for shaping helical flights and auger billets based on the componentic methods

Based on the use of the componetic methods the universal method for the formalized description of the ways of shaping the helical flights and auger billets, obtained by different technological methods, has been developed. The method takes into account the number, composition and direction of shaping and auxiliary movements of the executive bodies in the coordinate system of technological equipment, the design features (shape) and direction of movements of the sections of the initial workpiece and the principle of its transformation to the spiral form, also the composition and direction of movements of the working surfaces of shaping tools. The results obtained can be used for the synthesis of new progressive schemes for shaping of helical flight and auger billets.

Cosmography as Cultural Capital: Power Struggle in the Visigothic Kingdom

Bourdieu's concept of cultural capital can be used to show that the cosmography of the learned bishop Isidore of Seville (560–636) was intended to acculturate the Visigothic elite to the Roman worldview, shedding new light on the relations of these two ruling elites. By being the provider and guardian of the culture, the Hispano–Roman aristocracy retained significant power and exercised its influence through the Catholic Church. Three dialectical categories — transformation of quantity to quality, development through contradiction, spiral forms of development — help advance the analysis of Isidore's cosmography. A case study on Isidorian planetary orbital values provides an illustration of this dialectical development. It was, therefore, cultural capital as exemplified by Isidore that enabled the Hispano–Roman aristocracy to maintain its position as a ruling elite.

New Spiral Form of Carbon Nitride with Ultrasoftness and Tunable Electronic Structures.

The structural diversity and multifunctionality of carbon nitride materials distinct from pure carbon materials are drawing increasing interest. Using first-principles calculations, we proposed a stable spiral structure of carbon nitride, namely spiral-C3N, which is composed of sp2-hybridized carbon and pyridine nitrogen with a 60° helical symmetry along the z-direction. The stability was verified from the cohesive energy, phonon spectrum, and elastic constants. Despite the strong covalent bonds of the spiral framework, the spiral-C3N exhibits a hardness lower than 12.00 GPa, in sharp contrast to the superhardness of cubic carbon nitrides reported in previous literature, which can be attributed to the unique porous configuration. The softness of the spiral-C3N was also confirmed by the small ideal strengths, which are, respectively, 33.00 GPa at a tensile strain of 0.22 along the [1̅21̅0] direction and 18.00 GPa at a shear strain of 0.52 in the (0001)[1̅21̅0] direction. Electronic band structure of spiral-C3N exhibits metallic features. A metal–semiconductor transition can be triggered by hydrogenation of the pyridine nitrogen atoms of spiral-C3N. Such a new three-dimensional spiral framework of sp2-hyperdized carbon and nitrogen atoms not only enriches the family of carbon nitride materials but also finds application in energy conversion and storage.

Hydraulic parameters of culverts from pipes with normal and spiral form of corrugation

The research paper is devoted to study of culverts from metal corrugated pipes (CMP) and helically corrugated steel pipes (HCSP). Modern design solutions of culverts from CMP and HCSP are differ as compared with used before (bottom with various types of roughness, inlet and outlet heads, type and size of corrugation) and there is not enough experimental data for their design. The aim of the study is to test CMP and HCSP models to determine their hydraulic parameters, such as roughness and resistance coefficient, critical bias and so on. The laboratory equipment and method of experimental study as well as results of the tests of CMP and HCSP with protective tray at the pipe bottom and without it under different operation modes are given in the research paper. The results of the study show that roughness coefficient under pressure hade mode can be determined using Norton equation only for HCSP, Norton and Einstein-Banks equations are corrected for CMP.

Three-Saddle-Foci Chaotic Behavior of a Modified Jerk Circuit with Chua’s Diode

This paper investigates the chaotic behavior of a modified jerk circuit with Chua’s diode. The Chua’s diode considered here is a nonlinear resistor having a symmetric piecewise linear voltage-current characteristic. To describe the system, we apply fundamental laws in electrical circuit theory to formulate a mathematical model in terms of a third-order (jerk) nonlinear differential equation, or equivalently, a system of three first-order differential equations. The analysis shows that this system has three collinear equilibrium points. The time waveform and the trajectories about each equilibrium point depend on its associated eigenvalues. We prove that all three equilibrium points are of type saddle focus, meaning that the trajectory of (x(t),y(t)) diverges in a spiral form but z(t) converges to the equilibrium point for any initial point (x(0),y(0),z(0)). Numerical simulation illustrates that the oscillations are dense, have no period, are highly sensitive to initial conditions, and have a chaotic hidden attractor.

Continuous three-dimensional path planning (CTPP) for complex thin parts with wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) is emerging as the main additive manufacturing (AM) technology used to produce medium-to-large-sized thin-walled parts (order of magnitude: 1 m) at lower cost. To manufacture a part with this technology, the path planning strategy used is the 2.5D. This strategy consists in slicing a 3D model into different planar layers parallel to each other. The use of this strategy limits the complexity of the topologies achievable in WAAM, especially those with large variations in curvature. It also involves several start/stops of the arc as it passes from one layer to another, which induces transient phenomena in which the control of the supply of energy and matter is complex. In this article, a new manufacturing strategy to minimize the start/stop phases of the arc to one unique cycle is presented. The goal of this strategy, called “Continuous Three-dimensional Path Planning” (CTPP) is to generate a continuous trajectory in spiral form for closed-loop thin parts. An adaptive wire speed coupled with a constant travel speed allows a modulation of the deposition geometry that ensures a continuous supply of energy and material throughout the manufacturing process. Using the 5-axis strategy coupled with CTPP allows the manufacture of closed parts with a procedure to determine the optimum closing area and parts on non-planar substrates useful for adding functionalities to an existing structure. Two geometries based on continuous manufacturing with WAAM technology are presented to validate this approach. The manufacturing of these parts with CTPP and several numerical evaluations have shown the reliability of this strategy and its capacity to produce complex new shapes with a good geometrical restitution, difficult or impossible to reach today using 2.5D with WAAM technology.

Ongoing flyby in the young multiple system UX Tauri

We present observations of the young multiple system UX Tauri to look for circumstellar disks and for signs of dynamical interactions. We obtained SPHERE/IRDIS deep differential polarization images in the J and H bands. We also used ALMA archival CO data. Large extended spirals are well detected in scattered light coming out of the disk of UX Tau A. The southern spiral forms a bridge between UX Tau A and C. These spirals, including the bridge connecting the two stars, all have a CO (3–2) counterpart seen by ALMA. The disk of UX Tau C is detected in scattered light. It is much smaller than the disk of UX Tau A and has a major axis along a different position angle, suggesting a misalignment. We performed PHANTOM SPH hydrodynamical models to interpret the data. The scattered light spirals, CO emission spirals and velocity patterns of the rotating disks, and the compactness of the disk of UX Tau C all point to a scenario in which UX Tau A has been perturbed very recently (∼1000 years) by the close passage of UX Tau C.

Conjugated linoleic acid loaded nanostructured lipid carrier as a potential antioxidant nanocarrier for food applications.

The encapsulation of fatty acids in nanocarrier systems is a very effective technique in improving their biological efficiency and controlled delivery. Nanostructured lipid carrier (NLC) is a major type of lipid‐based nanoparticle. This study is focused on producing nanolipid carrier containing conjugated linoleic acid and fortifying low‐fat milk using this nanoparticle. Nanostructured lipid carriers were produced by hot high‐shear homogenization containing 1.5% Poloxamer 407, cocoa butter as solid lipid, and conjugated linoleic acid as liquid oil in ratio of 10:1. Results showed that the nanoparticles sized 81 nm with monomodular dispersity and the system was stable at 4 and 22°C for 40 days. Zeta potential and encapsulation efficiency (%EE) were −15.8 mV and 98.2%, respectively. Scanning electron microscopy (SEM) showed that the particles are in spiral form and small size and no significant aggregation was observed because of few changes in the system turbidity after storage time. The result of oxidative stability showed that using Nanostructured lipid carriers system resulted in lower malone dialdehyde production. Conjugated linoleic acid was protected at level of 3.9% of milk fatty acids in Nanostructured lipid carrier formulation during storage time. Based on these findings, Nanostructured lipid carriers system is an appropriate and stable nanocarrier system for delivery of nutraceuticals in foods and can be used in protecting them against oxidation, heating, and other processes in order to fortify foods and beverages.

Resuscitation of the Helicobacter pylori Coccoid Forms by Resuscitation Promoter Factor Obtained from Micrococcus Luteus.

Helicobacter pylori is a gram negative, spiral-shaped, and microaerophilic bacteria which can cause life-threatening diseases. It is known that more than 55% of the human population in the world is already infected by this bacterium. The traditional treatment of H. pylori infection consists of a combination of two or more antibiotics. However, H. pylori has evolved to turning its shape from spiral to coccoid form in the presence of antibiotics and this decreases the therapeutic efficacies of conventional antibiotic applications. Resuscitation promoter factor (RPF) is a protein secreted by Micrococcus luteus have significant resuscitation effects on some bacteria especially in the group of viable but non-culturable (VBNC) pathogens. However, there is no study in the literature investigating the resuscitation effects of RPF derived from M. luteus on H. pylori in order to change its form from coccoid to spiral. The purpose of this study is to investigate the resuscitation effect of RPF-containing metabolites isolated from M. luteus on the morphological transformation of H. pylori coccoid forms to spiral forms in order to increase their susceptibilities to antibiotic treatments. Rpf-containing metabolites were primarily obtained from M. luteus culture supernatants. H. pylori was exposed to five different conditions such as prolonged culture, incubation at + 4 °C, incubation at + 22°C, cultivation in PBS and treatment with kanamycin in order to induce transformations of bacteria to coccoid forms. Induced H.pylori coccoids were characterized by inverted microscope, UV spectrophotometer, SEM imaging, and flow-cytometer. As a result, it was found that the most suitable condition for inducing coccoid forms was cultivation of bacteria with kanamycin. Followingly, different concentrations of RPF-containing metabolites were applied on H. pylori coccoids induced by kanamycin. For the first time in this study, it was determined that the Rpf-containing metabolites obtained from M. luteus demonstrated very high resuscitation effect on kanamycin-induced H. pylori coccoid forms. This new approach for resuscitation of H. pylori coccoids is thought to play an important role in increasing the treatment effectiveness of the conventional antibiotics against the infection.

Spiral Delone sets and three distance theorem

We show that a constant angle progression on the Fermat spiral forms a Delone set if and only if its angle is badly approximable.

CFD simulation and experimental verification of the spatial and temporal distributions of the downwash airflow of a quad-rotor agricultural UAV in hover

The plant protection effect of an agricultural unmanned aerial vehicle (UAV) with multiple rotors is closely related to its speed and direction and the spatial and temporal distributions of the effective coverage of the downwash airflow. By combining compressible Reynolds-averaged Navier-Stokes (RANS) equations, the shear stress transport (SST) k-ω turbulence model, sliding grid technology and the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm, this paper establishes a computational fluid dynamics (CFD) model of the downwash airflow of the quad-rotor agricultural UAV in hover and discusses the distribution of the downwash airflow in the spatial and temporal dimensions. The simulation results show that most areas of the downwash airflow tend to be stable within 4.5 s, and due to the downward flow characteristics after the stabilization, the z-direction (perpendicular to the ground) velocity of the downwash airflow directly under the rotor is the highest with a maximum value of −8.96 m/s, which accounts for the main part of the downwash flow. The rotor downwash airflow flows downward in spiral form and the phenomenon of “contraction and expansion” is obvious during the downwash flow. Closer to the ground, the coverage area of the z-direction velocity is larger, the pressure distribution is more uniform, and the airflow exhibits an “upwash” phenomenon due to the “ground effect”. The test and simulation values at test points from 1 m to 2.5 m and 0.75 m exhibit the same variation trend with maximum relative errors of 10% and 15%, and the numerical simulation is accurate.

Dynamic structural insights into the molecular mechanism of DNA unwinding by the bacteriophage T7 helicase

The hexametric T7 helicase (gp4) adopts a spiral lock-washer form and encircles a coil-like DNA (tracking) strand with two nucleotides bound to each subunit. However, the chemo-mechanical coupling mechanism in unwinding has yet to be elucidated. Here, we utilized nanotensioner-enhanced Förster resonance energy transfer with one nucleotide precision to investigate gp4-induced unwinding of DNA that contains an abasic lesion. We observed that the DNA unwinding activity of gp4 is hindered but not completely blocked by abasic lesions. Gp4 moves back and forth repeatedly when it encounters an abasic lesion, whereas it steps back only occasionally when it unwinds normal DNA. We further observed that gp4 translocates on the tracking strand in step sizes of one to four nucleotides. We propose that a hypothetical intermediate conformation of the gp4–DNA complex during DNA unwinding can help explain how gp4 molecules pass lesions, providing insights into the unwinding dynamics of gp4.

Efficiency improvement of liquid piston compressor using metal wire mesh for near-isothermal compressed air energy storage application

Intermittent nature of power from renewable energy resources demands a large-scale energy storage system for their optimal utilization. Compressed air energy storage systems have the potential to serve as long-term large-scale energy storage systems. Efficient compressors are needed to realize a high storage efficiency with compressed air energy storage systems. Liquid piston compressor is highly effective in achieving efficient near-isothermal compression. The compression efficiency of the liquid piston can be improved with the use of heat transfer enhancement mechanism inside the compression chamber. In this study, a novel heat transfer enhancement technique using metal wire mesh is experimentally tested in a liquid piston compressor to improve compression efficiency. Metal wire meshes of aluminum and copper materials and different wire diameters along with various stroke times of compression are considered in the experimental design. A distinctive Archimedean spiral form of metal wire mesh is considered to facilitate heat transfer in the axial and radial direction inside the compression chamber. Experiments are conducted for the compression of air from the atmospheric pressure to about 280 kPa pressure at various stroke times of compression. Results show that the peak air temperature was reduced by 26–33 K with the use of metal wire mesh inside the liquid piston compressor. Both the materials are observed to be equally effective for temperature abatement. The use of metal wire mesh in liquid piston shifts the compression process towards the near-isothermal conditions. Furthermore, the isothermal efficiency of compression is evaluated to assess the potential for efficiency improvement with this technique. The metal wire mesh was observed to improve the isothermal efficiency of compression to 88–90% from the base efficiency of 82–84%. A 6–8% improvement in efficiency was observed at faster compression strokes signifying the efficacy of metal wire mesh to accomplish an efficient compression with a high power density.