Contact Structure Research Articles

Dynamical quantization of contact structures

Dynamical quantization of contact structures

On geometry of 2-nondegenerate CR structures of hypersurface type and flag structures on leaf spaces of Levi foliations

We construct canonical absolute parallelisms over real-analytic manifolds equipped with 2-nondegenerate, hypersurface-type CR structures of arbitrary odd dimension not less than 7 whose Levi kernel has constant rank belonging to a broad subclass of CR structures that we label as recoverable. For this we develop a new approach based on a reduction to a special flag structure, called the dynamical Legendrian contact structure, on the leaf space of the CR structure's associated Levi foliation. This extends the results of [23] from the case of regular CR symbols constituting a discrete set in the set of all CR symbols to the case of the arbitrary CR symbols for which the original CR structure can be uniquely recovered from its corresponding dynamical Legendrian contact structure. We find an explicit criterion for this recoverability. In particular, if the rank of the Levi kernel is 1 and the dimension of the CR manifold is not less than 7, then for each given signature of the reduced Levi form in the space of all CR symbols (which depend on continuous parameters) there are no more than 2 symbols for which the aforementioned recoverability fails, and while the present method is applicable for all but those 2 cases, they can be treated separately by the method of [23]. Our method clarifies the relationship between the bigraded Tanaka prolongation of regular symbols developed in [23] and their usual Tanaka prolongation, providing a geometric interpretation of conditions under which they are equal. Motivated by the search for homogeneous models with given nonregular symbols, we also describe a process of reduction from the original natural frame bundle, which is inevitable for structures with nonregular CR symbols. We demonstrate this reduction procedure for examples whose underlying manifolds have dimension 7 and 9.We show that, for any fixed rank r>1, in the set of all CR symbols associated with 2-nondegenerate, hypersurface-type CR manifolds of odd dimension greater than 4r+1 with rank r Levi kernel, the CR symbols not associated with any homogeneous model are generic, and, for r=1, the same result holds if the CR structure is pseudoconvex.

The interconnection of endoplasmic reticulum and microtubule and its implication in Hereditary Spastic Paraplegia

The endoplasmic reticulum (ER) and microtubule (MT) network form extensive contact with each other and their interconnection plays a pivotal role in ER maintenance and distribution as well as MT stability. The ER participates in a variety of biological processes including protein folding and processing, lipid biosynthesis, and Ca2+ storage. MTs specifically regulate cellular architecture, provide routes for transport of molecules or organelles, and mediate signaling events. The ER morphology and dynamics are regulated by a class of ER shaping proteins, which also provide the physical contact structure for linking of ER and MT. In addition to these ER-localized and MT-binding proteins, specific motor proteins and adaptor-linking proteins also mediate bidirectional communication between the two structures. In this review, we summarize the current understanding of the structure and function of ER-MT interconnection. We further highlight the morphologic factors which coordinate the ER-MT network and maintain the normal physiological function of neurons, with their defect causing neurodegenerative diseases such as Hereditary Spastic Paraplegia (HSP). These findings promote our understanding of the pathogenesis of HSP and provide important therapeutic targets for treatment of these diseases.

GaAs//Si Multijunction Solar Cells Fabricated via Mechanical Stack Technology Using Pd Nanoparticles and Metal-Assisted Chemical Etching

Multijunction solar cells (MJSCs) have attracted attention as next-generation solar cells. In particular, GaAs//Si-based MJSCs are highly efficient with low cost and are expected to gain new applications, such as on-vehicle integrations. In this article, we examined a highly efficient In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.49</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.51</sub> P/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.06</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.94</sub> As//Si three-junction solar cell. The bottom Si cell has a tunnel oxide passivated contact structure. The key technology used to fabricate this solar cell is a stacking method that uses Pd nanoparticles (Pd-NPs) and metal-assisted chemical etching (MacEtch) for the bonding interface, which is improved from our previous “smart stack” technology. The MacEtch method has a feature of selective etching for Si around a metal body. Pd-NPs selectively invade the Si cell through the surface of the Si oxide layer, thereby improving the bonding resistivity between the GaAs-based cell and Si cell. Further, this technology aids the management of the bonding gap width by controlling the Pd-NP invasion depth. As a result, an efficiency of 27.6% for the aperture area was attained. The proposed technology is useful for the connection of Si-based cells, enhancing the development of GaAs//Si-based tandem solar cells.

Interpreting Surface Large-Loop Time-Domain Electromagnetic Data for Deep Mineral Exploration Using 3D Forward Modeling and Inversion

Surface transient electromagnetic (TEM) data with large transmitter loops for deep mineral exploration are often complicated by the non-trivial coupling between extended sources and arbitrarily oriented geological targets. This case study reports a TEM field data set acquired across terranes with strong lateral inhomogeneity, which is responsible for the high inconsistency in TEM data patterns along the survey line, as well as for the negative TEM transients (sign reversal) at some near-central loop stations. 3D forward modeling and inversion, as maturing tools in recent years, offer unique opportunities to extract as much geological information from such data as possible. 3D forward simulations of representative synthetic models found that the phenomenon of sign reversal at some TEM stations is associated with compact conductors enclosed by the transmitter loop and receivers that are in the loop, but off the conductor–a situation that is common in large-loop TEM and can only be explained by 3D models. However, 3D inversion of the field data with a uniform subspace as the initial and reference model fails to converge, another point of evidence that 3D inversions of large-loop TEM data are more likely to be subject to stability issues. Our solution is to warm-start the inversion with the representative model in the forward simulation experiments as the initial model, so the ill-posed 3D inversion can escape from local minima. Finally, the vertical contact structure in our 3D-inversion model is verified by a resistivity cross section of the CSAMT method. Our case study demonstrates the demand and capability of 3D electromagnetic modeling and inversion for high-resolution deep mineral exploration. It also provides an easy-to-follow template for carrying out 3D interpretation for complex geology in practice.

К проблеме восстановления структуры контактов русских революционеров от рубежа веков до 1930-х гг.

В статье рассматривается вопрос о связях между русскими революционерами и деятелями культуры, тем или иным образом связанными с революционным движением в России в начале ХХ в. На основе различных источников показано, как некоторые известные исторические деятели, на первый взгляд не имевшие явных связей между собой, взаимодействовали и общались ради достижения своих политических целей. Также прослеживается связь между самими революционерами, не принадлежавшими подчас к одной партии или политическому течению. Таким образом обнаруживается довольно разветвленная сеть, состоящая из известных как в политике, так и в культуре лиц, оказавшая в результате серьезное воздействие на внутриполитическую ситуацию в России в период до и между двух революций. Среди них присутствуют: Владимир Жаботинский, Пинхас Рутенберг, Максим Горький, Леонид Андреев, Михаил Осоргин, Дмитрий Мережковский, Зинаида Гиппиус, Борис Савинков, Александра Коллонтай и др. Многие моменты во взаимоотношениях некоторых из них выявлены на основе материалов об убийстве революционерами священника Георгия Гапона. Основной же темой статьи является вскрытие различных узлов информационных сетей и способов коммуникации, созданных российскими социалистами в конце XIX –начале XХ в. с целью конспирации. The study focuses on the relationship between Russian revolutionaries and cultural figures, in one way or another associated with the revolutionary movement in Russia of the early 20th century. Using a wide variety of sources, it demonstrates how a number of prominent historical figures, who at first glance had no apparent connection with one another, cooperated and communicated to achieve their political goals. It also traces the link between the revolutionaries themselves, who sometimes did not belong to the same party or political current, thus revealing a rather wide network of famous political and cultural figures who had a significant impact on the internal political situation in Russia before and in-between the two revolutions. Among them were Vladimir Jabotinsky, Pinhas Rutenberg, Maxim Gorky, Leonid Andreyev, Mikhail Osorgin, Dmitry Merezhkovsky, Zinaida Gippius, Boris Savinkov, Alexandra Kollontai, and many others. Many aspects of their interrelationships came to light from the accounts of the murder of the priest Georgy Gapon by the revolutionaries. However, the focus of the paper is to dissect the different nodes of information networks and communication methods established by Russian socialists in the late 19th and early 20th centuries for conspiratorial purposes.

Fabrication and Properties of InGaZnO Thin-Film Transistors Based on a Sol-Gel Method with Different Electrode Patterns.

The preparation of thin-film transistors (TFTs) with InGaZnO (IGZO) channels using sol-gel technology has the advantages of simplicity in terms of process and weak substrate selectivity. We prepared a series of TFT devices with a top contact and bottom gate structure, in which the top contact was divided into rectangular and circular structures of drain/source electrodes. The field-effect performance of TFT devices with circular pattern drain/source electrodes was better than that with a traditional rectangular structure on both substrates. The uniform distribution of the potential in the circular electrode structure was more conducive to the regulation of carriers under the same channel length at different applied voltages. In addition, with the development of transparent substrate devices, we also constructed a hafnium oxide (HfO2) insulation layer and an IGZO active layer on an indium tin oxide conductive substrate, and explored the effect of circular drain/source electrodes on field-effect properties of the semitransparent TFT device. The IGZO deposited on the HfO2 dielectric layer by spin-coating can effectively reduce the surface roughness of the HfO2 layer and optimize the scattering of carriers at the interface in TFT devices.

Thermal‐Driven Soft‐Contact Triboelectric Nanogenerator for Energy Harvesting and Industrial Cooling Water Monitoring

In this paper, a quaternary dielectric soft-contact rotary triboelectric nanogenerator (QDSR-TENG) of low frictional resistance is fabricated for combining TENG with a shape memory alloy (SMA) engine. The introduction of rabbit fur brush and FEP brush results in charge pumps with a partially soft contact structure. Benefiting from the low friction loss of the structure, the QDSR-TENG can operate stably and continually for 100k cycles without significant output degradation. The SMA engine exhibits thermally induced phase transformation and super-elasticity and can be utilized for harnessing waste heat energy. The thermal-driven QDSR-TENG can operate with a water source of 43°C with a distinguishable response to the variation of temperatures. Such a low starting temperature not only promotes the harvesting of low-grade thermal energy, but also results in a self-monitoring industrial cooling water system. The coupled elastocaloric power and cooling cycle proposed in the thermal-driven QDSR-TENG opens a new paradigm for the application in energy harvesting and smart sensing.

Higher Rank Parabolic Geometries with Essential Automorphisms and Nonvanishing Curvature

We construct infinite families of regular normal Cartan geometries with nonvanishing curvature and essential automorphisms on closed manifolds for many higher rank parabolic model geometries. To do this, we use particular elements of the kernel of the Kostant Laplacian to construct homogeneous Cartan geometries of the desired type, giving a global realization of an elegant local construction due to Kruglikov and The, and then modify these homogeneous geometries to make their base manifolds compact. As a demonstration, we apply the construction to quaternionic contact structures of mixed signature, among other examples.

Effect of thermal annealing on the electronic parameters of Al/p-Si/Cu double Schottky barrier heights

In this work, performance enhancements of a double Schottky rectifier diode with Cu contact on top of p-type Si and a back-side-Al contact due to an optimized thermal annealing process are reported. A decrease of the ideality factor for non-ohmic and ohmic Schottky contacts from 3.17 to 1.15 could be observed in conjunction with a barrier height reduction from 0.59 eV to 0.48 eV by thorough hydrofluoric acid treatment prior to annealing the sample for 15 min. at 450 °C in N2 atmosphere. Moreover, the barrier height and built-in voltage values decreased by increasing frequency in the ohmic contact structure. The results presented in this work demonstrate such ohmic contacts to be potential candidates for high current and low resistance Schottky diodes and applications.

Boosting electrical output of nanostructured silicon hydrovoltaic device via cobalt oxide enabled electrode surface contact

Hydrovoltaic device exploits the omnipresent water evaporation or vapor through functional materials to generate power in a facile and environmentally manner. However, overlooking of the interfacial contact between electrodes and materials is one of the dominant hindering factors in further improving the electrical outputs. Here, we report a high-efficiency silicon nanowire (SiNW) arrays-based hydrovoltaic device featuring a cobalt oxide (CoOx) layer between the top electrode and SiNWs. The CoOx layer functions as a hole-selective layer that reinforces the interfacial charge selectivity and suppresses carrier recombination. Crucially, the unique design of the CoOx-capped SiNWs architecture enables surface contact with the top electrode instead of point contact, which expands the geometric contact area and provides minimal interfacial contact resistance. Benefiting from this facile yet effective contact structure design, the device yields an open-circuit voltage of 0.83 V, a short-circuit current of 160 μA, and a maximum power density of 20 μW·cm-2 (a record among analogous devices). We also showcase that the output power of four series-connected devices viably actuates various colored light-emitting diode (LED) arrays of 25 bulbs. This finding would initiate a promising orientation toward the fabrication of high-performance hydrovoltaic devices.

Effective Schottky barrier height and interface trap density reduction engineering using 2-dimensional reduced graphene oxide interlayer for metal-interlayer-semiconductor contact structure

The contact resistance at the metal-semiconductor (MS) interface has become the foremost challenge to ensuring high performance in nanoelectronics as devices are scaled down. A metal-interlayer-semiconductor (MIS) contact structure is a promising technique for Fermi-level unpinning to overcome the issue of fundamental contact resistance. Herein, an MIS contact structure with a 2-dimensional reduced graphene oxide (rGO) interlayer is proposed as an effective source/drain contact structure. The demonstration of a metal-rGO-semiconductor MIS (rGO MIS) contact structure with different interlayer thicknesses indicated that the rGO interlayer with a thickness of a few nanometers significantly enhanced the reverse current density (JR) by ∼2.0 × 103 times compared to that of the MS contact. In addition, the effective Schottky barrier height was reduced from 0.576 to 0.205 eV. This drastic improvement is attributed to the unique properties of rGO, such as its wide band gap, electrical conductivity, and Van der Waals interface leading to a metal-induced gap state reduction, tunneling resistance lowering, and passivation effect when it is adopted as an interlayer of the MIS contact. This result demonstrates the promising potential of using rGO as an MIS interlayer, which will pave the way toward high-performance emerging nanoelectronic devices.

Design and experimental study of piezoelectric driven flexible Braille contacts

A new flexible contact structure using the principle of air pressure amplification is proposed to enable better access to information for the blind. First, the structure and working principle of piezoelectric flexible Braille contacts were designed and analyzed, and the theoretical model of air pressure amplification and theoretical expressions were established. Then the gas–solid coupling simulation analysis was carried out using COMSOL Multiphysics software to derive the influencing factors of the system flexible contact amplification and the degree of influence of different gases on the contact output displacement, and the structure of flexible Braille contacts was tested experimentally. The experimental results show that when the diameter of the air cavity is 24 mm, the height of the cavity is 6 mm, the thickness of the flexible film is 0.1 mm, the contact height is 2 mm, the input voltage is 135 V, the resonance frequency reaches 196.5 Hz, the maximum output displacement of the piezoelectric flexible Braille contact is 0.286 mm, and the point display effect of the Braille contact is more significant, which verifies the feasibility of the device.

Simulation Analysis and Experimental Investigation of the Iron-Core Cup-Shaped Transverse Magnetic Field Contact

The transverse magnetic field (TMF) contact uses self-generated TMF to drive the arc movement and has been widely used in the field of vacuum breaking. An iron-core cup-shaped TMF contact was designed by adding an iron core and changing the parameters of the cup wall based on the structure of the traditional cup-shaped TMF contact to optimize the gap magnetic field distribution of the cup-shaped TMF contact and improve the force characteristics of the vacuum arc. From the aspects of simulation and experiment, the gap magnetic field characteristics, arc force, and vacuum arc characteristics of the iron-core cup-shaped TMF contact were studied. The simulation analysis model of the iron-core cup-shaped TMF contact was established by COMSOL Multiphysics software, and the gap magnetic field characteristics and arc force were analyzed. Compared with the traditional cup-shaped TMF contact, the tangential electromagnetic force on the arc is increased by 30%, and the radial electromagnetic force is reduced by 36%. The arcing processes of the iron-core cup-shaped TMF contact and the traditional cup-shaped TMF contact were analyzed through experiments. The results show that the iron-core cup-shaped TMF contact has a faster arc movement speed, longer movement duration, and less metal droplet splashing.

An innovative design of arrays-interpenetrated CZTSSe/MoO3 back interfacial contacts for improving the solar cell performance

It is widely known that the challenge of making good electrical contact at the back electrode interface will always follow us for high-efficient kesterite-type CZTSSe thin-film solar cells. Aiming at clarifying the correlation of device performance on the micro-structure of back interface, we come up with a new fresh design that introducing in-situ anodized MoO 3 porous arrays with regulated structural parameters acts as the back interfacial contact. Regards the such array-structures of interpenetrated CZTSSe and MoO 3 , the study reveals that the overall device performance is closely related to the micro-structure of the MoO 3 interface layer, and the optimized device efficiency can be improved to 9.00% from 6.31% (Ref. Mo-based cells), having a 32% increased J SC together with a 64% increase in FF. The performance improvement mechanism is analyzed in details. The interesting preliminary finding would indicate that the new strategy is very effective to form reliable electrical contact at the back interface for high-efficient CZTSSe solar cells. • New design of interpenetrated CZTSSe/MoO 3 arrays for innovative interfacial contact of CZTSSe solar cells. • Nearly 43% increase of efficiency from 6.31% to 9.00% is achieved. • Increase of J SC from 25.49 to 33.63 mA/cm 2 and FF from 60.4% to 63.65%. • Potential for revealing the effect of back contact structure on device performance.

The Tricalbin-Family Endoplasmic Reticulum-Plasma Membrane Tethering Proteins Attenuate ROS-Involved Caspofungin Sensitivity in Candida albicans.

The endoplasmic reticulum-plasma membrane (ER-PM) contacts are one kind of important membrane contact structures in eukaryotic cells, which mediate material and message exchange between the ER and the PM. However, the specific types and functions of ER-PM tethering proteins are poorly understood in the human fungal pathogen Candida albicans. In this study, we observed that the two tricalbin-family proteins, i.e., Tcb1 and Tcb3, were colocalized with the ER-PM contacts in C. albicans. Deletion of the tricalbin-encoding genes TCB1 and TCB3 remarkably reduced ER-PM contacts, suggesting that tricalbins are ER-PM tethering proteins of C. albicans. Stress sensitivity assays showed that the TCB-deleted strains, including tcb1Δ/Δ, tcb3Δ/Δ, and tcb1Δ/Δ tcb3Δ/Δ, exhibited hypersensitivity to cell wall stress induced by caspofungin. Further investigation revealed that caspofungin induced drastic reactive oxygen species (ROS) accumulation in the mutants, which was attributed to enhanced oxidation of Ero1 in the ER lumen. Removal of intracellular ROS by the ROS scavenger vitamin C rescued the growth of the mutants under caspofungin treatment, indicating that Ero1 oxidation-related ROS accumulation was involved in caspofungin hypersensitivity of the mutants. Moreover, deletion of the TCB genes decreased secretion of extracellular aspartyl proteinases, reduced transport of the cell wall protein Hwp1 from the cytoplasm to the cell wall, and attenuated virulence of the fungal pathogen. This study sheds a light on the role of ER-PM tethering proteins in maintenance of cell wall integrity and virulence in fungal pathogens. IMPORTANCE The endoplasmic reticulum-plasma membrane contacts are important membrane contact structures in eukaryotic cells, functioning in material and message exchange between the ER and the PM. We observed that the two tricalbin-family endoplasmic reticulum-plasma membrane contact proteins are required for tolerance to caspofungin-induced cell wall stress in the pathogenic fungus Candida albicans. The tricalbin mutants exhibited hypersensitivity to cell wall stress induced by caspofungin. Further investigation revealed that Ero1 oxidation-related reactive species oxygen accumulation was involved in caspofungin hypersensitivity of the tricalbin mutants. Moreover, loss of tricalbins reduced secretion of extracellular aspartyl proteinases, decreased transport of the cell wall proteins from the cytoplasm to the cell wall, and attenuated virulence of the fungal pathogen. This study uncovers the role of ER-PM tethering proteins in sustaining protein secretion, maintenance of cell wall integrity and virulence in fungal pathogens.

Fillability of small Seifert fibered spaces

AbstractOn small Seifert fibered spaces$M(e_0;\,r_1,r_2,r_3)$with$e_0\neq-1,-2,$all tight contact structures are Stein fillable. This is not the case for$e_0=-1$or$-2$. However, for negative twisting structures it is expected that they are all symplectically fillable. Here, we characterise fillable structures among zero-twisting contact structures on small Seifert fibered spaces of the form$M\left({-}1;\,r_1,r_2,r_3\right)$. The result is obtained by analysing monodromy factorizations of associated planar open books.

Hamiltonian systems on almost cosymplectic manifolds

We determine the Hamiltonian vector field on an odd dimensional manifold endowed with almost cosymplectic structure. This is a generalization of the corresponding Hamiltonian vector field on manifolds with almost transitive contact structures, which extends the contact Hamiltonian systems. Applications are presented to the equations of motion on a particular five-dimensional manifold, the extended Siegel-Jacobi upper-half plane X˜1J. The X˜1J manifold is endowed with a generalized transitive almost cosymplectic structure, an almost cosymplectic structure, more general than transitive almost contact structure and cosymplectic structure. The equations of motion on X˜1J extend the Riccati equations of motion on the four-dimensional Siegel-Jacobi manifold X1J attached to a linear Hamiltonian in the generators of the real Jacobi group G1J(R).

Effects of Loading Stress and Velocity on Compression and Particle Breakage Behaviour of Waste Rocks in Backfill Coal Mining

Coal mine waste rocks, mainly broken gangue, can be used as filling materials to backfill into goafs. Under the overburden load, the backfill body is vulnerable to compressive deformation and particle breakage. With the increase in mining depth, the overlying strata will impose different loads on waste rock filling materials at different loading velocities, which further affect the material compressive deformation and particle breakage. In this paper, an experimental scheme and a loading device are designed to study the influence of loading stress and velocity on the compressive deformation and particle size distributions of the backfill materials before and after compression. The results show that the axial strain of the gangue filling materials increases rapidly with the axial stress and then gradually stabilizes, showing a logarithmic functional relationship. Increasing the loading velocity will destroy the contact structures among the gangue particles and cause a larger deformation to the filling materials. When the loading stress is relatively low (5 MPa), the gangue particles with a size larger than 20 mm have a stronger bearing capacity compared with particles of 16–20 mm, which are the first particles to be crushed under these conditions. Further increasing the loading velocity will increase the breakage degree of the filling materials. The breakage ratio (BM) has a logarithmic functional relationship with the loading stress and the loading velocity. When the ground stress is lower than 5 MPa, the content of coarse particles should be increased to enhance the bearing capacity of the gangue materials; when the ground stress is higher than 10 MPa, the content of fine particles should be increased to reduce the porosity ratio and the particle breakage ratio.

Impact of Ring-Shaped Collector Contact on Total Ionizing Dose Susceptibility of Vertical n-p-n Bipolar Transistors

The impact of ring-shaped collector contact (RCC) on total ionizing dose (TID) susceptibility of 40-V vertical n-p-n bipolar transistors is investigated. The 60Co <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray irradiation experiment shows that the devices with RCC suffer less current gain degradation than their counterparts with conventional collector contact structure, which is independent of the emitter area and bias condition during irradiation. Technology computer-aided design (TCAD) simulation results indicate that the enhancement in radiation tolerance of the RCC devices should be attributed to the mitigation of trap-assisted carrier recombination at the Si/SiO2 interfaces near emitter–base (EB) junction rather than the concentration or distribution variations of radiation-induced traps. Moreover, the mitigation of carrier recombination in RCC devices could result from the creation of new current flow paths that suppress the diffusion of injected electrons toward the trap-enriched Si/SiO2 interfaces.