Reduction In Gap Size Research Articles

Electrode materials optimize operating voltage and switching speed in micro/nano plasma ultrafast devices

Abstract The trade-off between ultrahigh speed and low operating voltage is a major challenge in the continuous improvement of modern electronics. Although micro/nano plasma devices have demonstrated the potential of picosecond switching speed and high output power, surpassing traditional electronic devices, versatile methods for optimizing the operating voltage and switching speed are highly desired. Here, an optimization scheme based on the work function of the electrode materials is reported, which reduces the operating voltage and improves the switching speed. Compared with traditional methods, such as narrowing gaps or distorting electric fields, this approach offers advantages such as reducing production costs, enhancing consistency, and improving tunability. The experimental results show that using silver as a low-work-function electrode material can reduce the operating voltage by 55% to 180 V and increase the switching speed by 58% to 7.1 V ps−1 compared to platinum, which is equivalent to a 71% reduction in gap size. In addition, the underlying working mechanisms and inherent advantages of the approach are demonstrated, providing new insights for the ultrahigh switching speed and low-power application of micro/nano plasma devices, such as high-speed communication and ultrafast electronics.

Evaluation of the Bond Strength between the Acrylic Teeth and Reinforced or Non-reinforced Complete Denture Base.

The aim of this study was to examine whether the method of surface treatment of the acrylic teeth and reinforcement of the denture base (carbon fibers) affect the reduction of stress concentration for gap initiation at the interface of acrylic teeth and denture base as a measure of bond strength. Samples of cross-sections of acrylic teeth and denture base were isolated from four pairs of complete acrylic dentures (with and without reinforcement of the denture base) and were subsequently subjected to compressive loading in a universal testing machine simulating two different occlusions. Selected groups of acrylic teeth (central incisors, first premolars, and first molars) from complete dentures were treated in various ways (untreated, mechanical, chemical, and mechanical-chemical). The gap size at the interface of acrylic tooth and denture base was measured using a light inverted microscope on selected acrylic teeth of individual quadrants. The one-way analysis of variance was used to investigate the influence of denture base reinforcement and different methods of surface treatment of the acrylic tooth on bond strength at the level of statistical significance of p ≤ 0.001. Microscopic analysis of gap size measured at five selected points at the interface between the acrylic teeth and the base of the complete denture ranged from 40 to 144 micrometers. The one-way analysis of variance showed a statistically significant difference between the arithmetic means of the measured gap sizes concerning different methods of surface treatment of the acrylic teeth. The fracture strength, or load-bearing capacity, of complete dentures reinforced with carbon fibers was increased compared to complete dentures with non-reinforced bases. Reduction in gap size at the interface between the acrylic teeth and the base of complete dentures was influenced by the mechanical-chemical treatment of the lower surface of acrylic teeth, while reinforcement of the complete denture base with carbon fibers had no effect on the bond strength.

Laser Scribing for Electrode Patterning of Perovskite Spectrometer-Grade CsPbBr3 Gamma-ray Detectors

Making semiconductor radiation detectors that work at room temperature relies heavily on the deposition and pixelation of electrodes. Electrode patterning of perovskite solar cells widely implements laser scribing techniques, which is a convenient, scalable, and inexpensive technique. However, this method has not found its application in radiation detector patterning yet, and the question whether laser scribing can achieve high-quality patterns with minimum damage to a detector crystal and low interpixel cross-talk remains largely unanswered. To prove that laser scribing is a practical method for electrode patterning on perovskite CsPbBr3 detectors, we use the material to create a variety of patterns. A very low lateral leakage current (60 nA at 10 V) and high mobility-lifetime product (9.7(3) × 10-4 cm2/V) were observed between the pixel and the guard ring in tests of single-pixel devices with a separation of 200 or 100 μm between the central electrode and the guard ring. The 122 and 136 keV photopeaks in 57Co gamma-ray spectra were very well resolved with an energy resolution of up to 6.1% at 122 keV. A further reduction in gap size to 50 μm is conceivable, but more process optimization is needed.

High-performance magneto-rheological clutches for direct-drive actuation: Design and development.

This paper presents an improved design, complete analysis, and prototype development of high torque-to-mass ratio Magneto-Rheological (MR) clutches. The proposed MR clutches are intended as the main actuation mechanism of a robotic manipulator with five degrees of freedom. Multiple steps to increase the toque-to-mass ratio of the clutch are evaluated and implemented in one design. First, we focus on the Hall sensors’ configuration. Our proposed MR clutches feature embedded Hall sensors for the indirect torque measurement. A new arrangement of the sensors with no effect on the magnetic reluctance of the clutch is presented. Second, we improve the magnetization of the MR clutch. We utilize a new hybrid design that features a combination of an electromagnetic coil and a permanent magnet for improved torque-to-mass ratio. Third, the gap size reduction in the hybrid MR clutch is introduced and the effect of such reduction on maximum torque and the dynamic range of MR clutch is investigated. Finally, the design for a pair of MR clutches with a shared magnetic core for antagonistic actuation of the robot joint is presented and experimentally validated. The details of each approach are discussed and the results of the finite element analysis are used to highlight the required engineering steps and to demonstrate the improvements achieved. Using the proposed design, several prototypes of the MR clutch with various torque capacities ranging from 15 to 200 N·m are developed, assembled, and tested. The experimental results demonstrate the performance of the proposed design and validate the accuracy of the analysis used for the development.

Computational study on synovial fluid flow behaviour in cartilage contact gap under osteoarthritic condition

This study numerically investigates the pathological changes of fluid flow in cartilage contact gap due to the changes in cartilage surface roughness and synovial fluid characteristics in osteoarthritic (OA) condition. First, cartilage surface topographies in both healthy and OA conditions are constructed using a numerical approach with consideration of both vertical and horizontal roughness. Then, constitutive equations for synovial fluid viscosity are obtained through calibration against previous experimental data. Finally, the roughness and synovial fluid information are input into the gap flow model to predict the gap permeability. The results show that the rougher surface of OA cartilage tends to decrease gap permeability by around 30%–60%. More importantly, with the reduction in gap size, the decrease in gap permeability becomes more significant, which could result in an early fluid ultrafiltration into the tissue. Moreover, it is demonstrated that the pathological synovial fluid has more deleterious effects on the gap permeability than the OA cartilage surface, as it could potentially increase the gap permeability by a few hundred times for pressure gradients less than 106 Pa/m, which could inhibit the fluid ultrafiltration into the tissue. The outcomes from this research indicate that the change in fluid flow behaviour in contact gap in OA condition could significantly affect the function of articular joints.

Renormalization of the Mott gap by lattice entropy: The case of 1T- TaS2

In many transition-metal oxides and dichalcogenides, the electronic and lattice degrees of freedom are strongly coupled, giving rise to remarkable phenomena, such as metal-insulator transition (MIT) and charge-density wave (CDW) order. We study this interplay by tracing the instant electronic structure under ab initio molecular dynamics. Applying this method to a 1T-TaS2 layer, we show that the CDW-triggered Mott gap undergoes a continuous reduction as the lattice temperature raises, despite a nearly constant CDW amplitude. Before the CDW order undergoes a sharp first-order transition around the room temperature, the dynamical CDW fluctuation already shrinks the Mott gap size by half. The gap size reduction is one order of magnitude larger than the lattice temperature variation. Our calculation not only provides an important clue to understand the thermodynamics behavior in 1T-TaS2, but also demonstrates a general approach to quantify the lattice entropy effect in MIT.

A packed-bed DBD micro plasma reactor for CO2 dissociation: Does size matter?

DBD plasma reactors are of great interest for environmental and energy applications, such as CO2 conversion, but they suffer from limited conversion and especially energy efficiency. The introduction of packing materials has been a popular subject of investigation in order to increase the reactor performance. Reducing the discharge gap of the reactor below one millimetre can enhance the plasma performance as well. In this work, we combine both effects and use a packed-bed DBD micro plasma reactor to investigate the influence of gap size reduction, in combination with a packing material, on the conversion and efficiency of CO2 dissociation. Packing materials used in this work were SiO2, ZrO2, and Al2O3 spheres as well as glass wool. The results are compared to a regular size reactor as a benchmark. Reducing the discharge gap can greatly increase the CO2 conversion, although at a lower energy efficiency. Adding a packing material further increases the conversion when keeping a constant residence time, but is greatly dependent on the material composition, gap and sphere size used. Maximum conversions of 50–55% are obtained for very long residence times (30 s and higher) in an empty reactor or with certain packing material combinations, suggesting a balance in CO2 dissociation and recombination reactions. The maximum energy efficiency achieved is 4.3%, but this is for the regular sized reactor at a short residence time (7.5 s). Electrical characterization is performed to reveal some trends in the electrical behaviour of the plasma upon reduction of the discharge gap and addition of a packing material.

A new approach to treat bone gaps after midfacial and zygomatic fractures with a collagen membrane.

The aim of the study was to analyze the eligibility of resorbable collagen membrane in the treatment of midfacial fractures to prevent gap formation and subsequent cheek tissue retraction. We included nine patients (six males, three females; mean age 51; range 20-73years; mean bone gap size 8.03×13.12mm) in a retrospective study design. The defect size was assessed by ultrasound. After a healing period of 4 to 55weeks, treatment resulted in a significant reduction of gap size (residual mean bone gap size 6.14×7.32mm). Native resorbable collagen membrane is a promising tool to reduce the size of bony gap in midfacial defects.

POSTERIOR PHARYNGEAL WALL AUGMENTATION WITH MUSCULAR FLAP VERSUS MUSCULOMUCOSAL FLAP FOR CORRECTION OF VELOPHARYNGEAL INCOMPETENCE

This study was aimed to evaluate and compare the posterior pharyngeal wall augmentation using muscular flap versus musculomucosal flap for correction of velopharyngeal incompetence (VPI). Patients and methods: this study was conducted on twenty children (13 males and 7females) complaining from VPI with age ranging between 6.5 and 13 years with a mean of age 8.7 years. All patients were treated surgically using posterior pharyngeal wall augmentation. Patients were classified into two equal groups according to the type of flap technique used for posterior pharyngeal wall augmentation. Group I included10 patients (7 males and 3 females) were treated by muscular flap. Group II included10 patients (6 males and 4 females) were treated by musculomucosal flap. The preoperative and postoperative assessments for patients with VPI included clinical examination of the voice, nasopharyngoscopy and computed tomography (CT) scans. Results: Regarding clinical presentation (hypernasality and nasal regurgitation of fluid), all patients in both groups had no nasal regurgitation of fluid or food which represents 100%. As regard the overall nasalance results (Nasal sentence) measured by nasometry in both groups there was noticeable improvement. But when comparing overall nasalance results between both groups there was no significant difference .Competence and borderline closure was achieved in 65% for patients of both groups. The VP gap size reduction was achieved in both groups, however there was no significant difference regarding reduction of median VP gap size. Conclusion: At the end, as there no significant difference in the results of both groups: the myomucosal flap technique for posterior pharyngeal wall augmentation is simple and easier than the muscular flap technique and the posterior pharyngeal wall augmentation is a good technique for treatment of VPI

Assessment of thermal–hydraulic correlations for narrow rectangular channels with high heat flux and coolant velocity

The focus of the paper is on the evaluation of the correlations for predicting single-phase friction, single- and two-phase forced convection heat transfer coefficients in rectangular narrow channels, where the wall heat flux and the coolant flow can reach relatively high values.For this purpose, several correlations are reviewed and assessed against the SULTAN-JHR experiments. These tests were performed at CEA-Grenoble with upward water flow in two vertical uniformly heated narrow rectangular channels with gap of 1.51 and 2.16mm. The experimental conditions range between 0.2 and 0.9MPa for the pressure; 0.5–18m/s for the coolant velocity and between 0.5 and 7.5MW/m2 for the heat flux.The use of an appropriate turbulent friction factor leads to good comparison with the experimental data.The analysis of the single-phase turbulent heat transfer coefficient shows that the standard correlations (e.g. Dittus–Boelter) significantly under-estimate the heat transfer coefficient, especially at high Reynolds number. Therefore, new best-fitting correlations are derived. It is also observed that a reduction in gap size may lead to the enhancement of the heat transfer.The heat transfer is also under-estimated in two-phase flow if standard correlations (e.g. Jens–Lottes) are employed; however, good comparison with the experimental data are obtained with more appropriate models for fully developed boiling, such as the Forster–Greif correlation.The global accuracy associated to these correlations is also quantified in a rigorous manner.

Effect of hygroscopic expansion of resin filling on interfacial gap and sealing: a confocal microscopy study

To measure dimensional changes due to hygroscopic expansion and their effect on interface gaps and sealing in four light-cured restorative materials using an original confocal microscopic methodology. The materials tested were an ormocer (Admira [Voco]), a compomer (Dyract AP [Dentsply]), a hybrid composite (Spectrum [Dentsply]), and a nanohybrid composite (Esthet·X [Dentsply]). Water sorption was evaluated by weighing material disks after immersion. Hygroscopic expansion was measured from volumetric variations of material fillings in cylindrical cavities in dentin slices; the interfacial gap size was obtained from the same cavities using a novel confocal microscopic method. Microleakage was evaluated in cavities prepared in extracted third molars. Measurements followed water immersion for 24 h, 1 week, 4 weeks, and 8 weeks. A factorial ANOVA, the Student Newman Keuls test for post-hoc comparisons, the Student's t-test, and the Pearson test were used for the statistical analysis (p < 0.05). Positive correlations were found among water sorption, hygroscopic expansion, and sealing. Hygroscopic expansion reduced post-polymerization interfacial gaps and improved cavity sealing. Dyract AP and Admira showed the highest water sorption, hygroscopic expansion, and gap size reduction. 1. The proposed methodology is valid to measure hygroscopic expansion and interfacial gap. 2. Water sorption and hygroscopic expansion are positively correlated, and hygroscopic expansion, gap size, and sealing are also positively correlated. 3. The adhesive influences the interfacial gap size and its variation after hygroscopic expansion. 4. Hygroscopic expansion reduces the interfacial gaps generated by polymerization shrinkage and improves cavity sealing.

Arrays: Gap Size Reduction and Increased SERS Enhancement in Lithographically Patterned Nanoparticle Arrays by Templated Growth (Advanced Optical Materials 4/2013)

Templated growth of gold nanostructures has been achieved by V. Merk et al. On page 313, lithographic patterning of nanoparticle arrays is followed by deposition and annealing of thin gold layers, promoting recrystallization and growth of the initially patterned particles and, consequently, a reduction of the interparticle spacing. This results in a strong local field enhancement of the incident illumination, evidenced by a significant increase in surface-enhanced Raman scattering. The lattice period of the array in the image is 75 nm.

Gap Size Reduction and Increased SERS Enhancement in Lithographically Patterned Nanoparticle Arrays by Templated Growth

A general method for reducing interparticle gap size in lithographically patterned metal particle arrays is introduced. Dense gold nanoparticle arrays are fabricated by electron beam lithography and the patterned structure is subsequently covered with thin layers of gold and annealed at a high temperature. This results in ripening of the initially patterned particles and in reduced interparticle distances, as well as in an improvement in the optical properties through gold recrystallization and grain growth. At intermediate processing steps, a distinctly bimodal particle distribution can be realized for effective nanofocusing of incident radiation into a high density of hotspots. 3D finite‐difference time domain simulations and surface‐enhanced Raman scattering experiments confirm that high local electric fields arise in such structures, resulting in enhancement of the Raman signals on the order of 106. This combination of lithographic patterning and self‐assembly can be used to obtain novel plasmonic nanostructures that cannot be directly fabricated by other means.

Fabrication of 6 nm gap on silicon substrate for power-saving appliances

We document a thermal oxidation process for the reproducible fabrication of 6-nm gaps on silicon-on-insulator (SOI) substrate. Nanogaps sizes of this dimension are implicated to eliminate contributions from double-layer capacitance in the dielectric sensing of proteins or nucleic acids. The method combines conventional photolithography and pattern-size reduction technique to create a desired-size gap. The gaps are physically characterized with a field emission scanning electron microscopy (FESEM). Preliminary results show that gap-size reduction provides an improvement in conductivity, permittivity and capacitance parameters, reflecting the potential applications of the fabricated structures in low-power consuming electrical devices. The task is completed with two chrome masks: the first mask is for the nanogap pattern and the second one is for the electrodes. An improved resolution of pattern size is obtained by controlling the oxidation time of the final cycle. The reproducibility of the method is proven in triplicate experiments. We believe the method can be used in the industrial production of desired-size nanogaps on a variety of low-cost substrates. Key words: Nanogap, sequential oxidation, wet etching, double-layer capacitance, dielectric sensing, biomolecules.

Fabrication of 6 nm gap on silicon substrate for power- saving appliances

We document a thermal oxidation process for the reproducible fabrication of 6-nm gaps on silicon-on-insulator (SOI) substrate. Nanogaps sizes of this dimension are implicated to eliminate contributions from double-layer capacitance in the dielectric sensing of proteins or nucleic acids. The method combines conventional photolithography and pattern-size reduction technique to create a desired-size gap. The gaps are physically characterized with a field emission scanning electron microscopy (FESEM). Preliminary results show that gap-size reduction provides an improvement in conductivity, permittivity and capacitance parameters, reflecting the potential applications of the fabricated structures in low-power consuming electrical devices. The task is completed with two chrome masks: the first mask is for the nanogap pattern and the second one is for the electrodes. An improved resolution of pattern size is obtained by controlling the oxidation time of the final cycle. The reproducibility of the method is proven in triplicate experiments. We believe the method can be used in the industrial production of desired-size nanogaps on a variety of low-cost substrates. Key words: Nanogap, sequential oxidation, wet etching, double-layer capacitance, dielectric sensing, biomolecules.

Effects of electric and magnetic fields on the electronic properties of zigzag carbon and boron nitride nanotubes

We have investigated the electronic properties of zigzag CNTs and BNNTs under the external transverse electric field and axial magnetic field, using tight binding approximation. It was found that after switching on the electric and magnetic fields, the band modification such as distortion of the degeneracy, change in energy dispersion, subband spacing and band gap size reduction occurs. The band gap of zigzag BNNTs decreases linearly with increasing the electric field strength but the band gap variation for CNTs increases first and later decreases (Metallic) or first hold constant and then decreases (semiconductor). For type (II) CNTs, at a weak magnetic field, by increasing the electric field strength, the band gap remains constant first and then decreases and in a stronger magnetic field the band gap reduction becomes parabolic. For type (III) CNTs, in any magnetic field, the band gap increases slowly until reaches a maximum value and then decreases linearly. Unlike to CNTs, the magnetic field has less effects on the BNNTs band gap variation.

Material Engineering for Nano Structure Formation: Fabrication and Characterization

Abstract Abstract. The technology development for nano structure formation using standard CMOS process-basedmethod capable of fabricating precisely control nano wire and Nanogap formation were demonstrated.The fabrication of nanoscale patterns with dimensions of 50 nm or less has been the goal of manyresearchers for potential applications as various sensing element, using improved Photolithographycoupled with plasma oxidation and by simultaneous application of reactive ion etcher and oxidationfurnace, step wise patterning and oxidation was introduced for size expansion and trimming nanogap andNanowire fabrication from micro sizes down to nano sizes <30nm. To demonstrate the quality of thefabricated nanogap, the fabricated structure is optically and electrically characterized with a fieldemission scanning electron microscope (FESEM) and dielectric analyzer (DA). To characterized thefabricated nanogap, an electrical characterization of the structures by dielectric analyzer (DA) shows anenhanced permittivity and capacity with the reduction of gap size, and Nano wire of lowest dimension of1.5 nm was obtained with improved conductivity, suggesting the potential of the fabricated devices forapplications in sensitive and selective detection of biomolecules with very low level of power supply.© 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Bina Nusantara University.Keywords:

The Rate of Polymerase Release upon Filling the Gap between Okazaki Fragments Is Inadequate to Support Cycling during Lagging Strand Synthesis

Upon completion of synthesis of an Okazaki fragment, the lagging strand replicase must recycle to the next primer at the replication fork in under 0.1 s to sustain the physiological rate of DNA synthesis. We tested the collision model that posits that cycling is triggered by the polymerase encountering the 5′-end of the preceding Okazaki fragment. Probing with surface plasmon resonance, DNA polymerase III holoenzyme initiation complexes were formed on an immobilized gapped template. Initiation complexes exhibit a half-life of dissociation of approximately 15 min. Reduction in gap size to 1 nt increased the rate of dissociation 2.5-fold, and complete filling of the gap increased the off-rate an additional 3-fold ( t 1/2 ∼ 2 min). An exogenous primed template and ATP accelerated dissociation an additional 4-fold in a reaction that required complete filling of the gap. Neither a 5′-triphosphate nor a 5′-RNA terminated oligonucleotide downstream of the polymerase accelerated dissociation further. Thus, the rate of polymerase release upon gap completion and collision with a downstream Okazaki fragment is 1000-fold too slow to support an adequate rate of cycling and likely provides a backup mechanism to enable polymerase release when the other cycling signals are absent. Kinetic measurements indicate that addition of the last nucleotide to fill the gap is not the rate-limiting step for polymerase release and cycling. Modest (approximately 7 nt) strand displacement is observed after the gap between model Okazaki fragments is filled. To determine the identity of the protein that senses gap filling to modulate affinity of the replicase for the template, we performed photo-cross-linking experiments with highly reactive and non-chemoselective diazirines. Only the α subunit cross-linked, indicating that it serves as the sensor.

Fabrication of Lateral Polysilicon Gap of Less than 50 nm Using Conventional Lithography

We report a thermal oxidation process for the fabrication of nanogaps of less than 50 nm in dimension. Nanogaps of this dimension are necessary to eliminate contributions from double-layer capacitance in the dielectric detection of protein or nucleic acid. The method combines conventional photolithography and pattern-size reduction techniques. The gaps are fabricated on polysilicon-coated silicon substrate with gold electrodes. The dimensions of the structure are determined by scanning electron microscopy (SEM). An electrical characterization of the structures by dielectric analyzer (DA) shows an improved conductivity as well as enhanced permittivity and capacity with the reduction of gap size, suggesting its potential applications in the detection of biomolecule with very low level of power supply. Two chrome Masks are used to complete the work: the first Mask is for the nanogap pattern and the second one is for the electrodes. An improved resolution of pattern size is obtained by controlling the oxidation time. The method expected to enable fabrication of nanogaps with a wide ranging designs and dimensions on different substrates. It is a simple and cost-effective method and does not require complicated nanolithography process for fabricating desired nanogaps in a reproducible fashion.

Pattern Size Reduction Effect via a “Mix and Match” Sequential Imprinting Technique

Nanoimprint lithography is traditionally thought of as a one-to-one pattern replication process, where the negative of the surface relief pattern from a mold is reproduced exactly onto a resist material. As such, each pattern design will require a mold to be fabricated with the pattern required. The mold used is typically fabricated by various lithographic processes, many of which are costly and time-consuming. In this work, we report the use of a "mix and match" sequential imprinting technique where line-space patterns of different gap sizes were achieved through the different combinations of feature size and relative alignments of the molds. More significantly, patterns with gap sizes smaller than the molds were obtained, resulting in a size reduction effect. A gap size reduction as high as 93% had been achieved in imprinted polystyrene and we have exploited the patterns as shadow masks used for the deposition of nanometer sized metal lines. The main advantage of this gap size reduction effect lies in the tunability of the process, which removes the need for the design and purchase of newer and more expensive imprinting molds.