Gap Resistance Research Articles

Treatment abandonment-continuity factors

Adherence to medical treatment is a fundamental process for patient well-being, but can be affected by a number of factors both internal and external. Factors that can influence adherence include economic and social problems, urgency of treatment, fear of side effects, and the stigma associated with the disease. The importance of establishing a collaborative relationship and therapeutic alliance between the patient and the health professional to improve adherence is emphasized. The need for awareness on the part of both health care actors is highlighted, recognizing that therapeutic adherence is fundamental for successful treatment. The importance of overcoming the economic gap and patient resistance to spending to ensure effective medical care is also suggested.

Gap Resistance and Tensile Strength of a Q Suture Technique During Curved Loading: An ExVivo Porcine Flexor Tendon Study.

This study aimed to determine the mechanical properties of the double Q suture technique in angular motion and to compare the gap formation associated with tendon repairs during curved and linear loading. Eighty porcine flexor tendons were repaired with one of two 4-strand sutures: double Q suture or double modified Kessler plus peripheral running sutures. The repaired tendons were cyclically loaded sequentially against a pulley with a radius of 2.0, 1.5, and 1.0 cm or linearly without any pulleys. The number of tendons that formed an initial or 2-mm gap at the repair site during cyclic loading, the gap size between tendon ends when cyclic loading ended, and the ultimate strength were recorded. The gap at the repair site formed gradually from the dorsal to volar aspect during curved loading. No double Q repairs, but half of the double Kessler plus running suture repairs, formed an initial or 2-mm gap on the volar aspect during curved loading. The double Q group had a significantly smaller gap size on the dorsal aspect than the double Kessler plus running suture group at all three radii of curvature. The ultimate strength was similar between the two groups. There were no significant differences in linear motion between these two repairs. The double Q suture is superior to the conventional 4-strand tendon core suture plus running peripheral sutures in gap resistance in angular motion. This study provides insight into the formation of an unbalanced gap on the dorsal and volar aspects of tendon repair during curved loading. The double Q suture provides a simple and efficient option for flexor tendon repair considering the high risk of gap formation on the dorsal aspects of the tendon repair in angular motion.

Achieving High-Performance Self-Powered Visible-Blind Ultraviolet Photodetection Using Alloy Engineering.

The exploration and development of self-powered visible-blind ultraviolet photodetectors (VBUV PDs) with high responsivity and wavelength selectivity have far-reaching significance for versatile applications. Although In2O3 shows potential for UV detection due to good UV absorption and electrical transport properties, the poor wavelength selectivity impedes further application in VBUV PDs. Here, a self-powered photoelectrochemical-type (PEC) VBUV PD is demonstrated by using gallium-indium oxide alloys (Ga-In OAs). The self-powered Ga-In OAs-based PEC VBUV PDs exhibit good VBUV photodetection performance, including a high responsivity of 50.04 mA/W and a high detectivity of 6.03 × 1010 Jones under 254 nm light irradiation, a good wavelength selectivity (UV/visible light rejection ratio of 262.45), and a fast response time (0.45/0.38 s). The good self-powered VBUV detection performance of Ga-In OAs is attributed to the larger band gap and smaller charge-transfer resistance induced by alloy engineering, which not only suppresses the absorption of visible light but also accelerates interfacial charge transfer. Moreover, an underwater optical communication system is demonstrated by using the self-powered Ga-In OAs PEC VBUV PDs. This study demonstrates that alloy engineering is a powerful tool to improve the performance of In2O3-based PEC PDs, and Ga-In OAs have great application potential for underwater optoelectronic devices.

Failure mechanism of parallel gap resistance welding joint between Ag foil and GaAs solar cell by temperature cycling

Reliability of joints in solar arrays significantly influences the service life of satellites. Interface between solar cell and interconnector experiences serious temperature cycling during space service which would further lead to failure. To further improve the interface joining thermal reliability, elucidation of the interface formation and corresponding microstructure evolution during thermal fatigue is necessary. In this study, parallel gap resistance welded (PGRW) multi-layered joint between GaAs solar cell and Ag foil are subjected to different temperature cycling tests (−160–120 °C, −165–160 °C) with various cycles. Obtained results confirm the joining mechanism of the joint as solid-solution interdiffusion between Ag foil and Au surface of solar cell electrode. Also, conducted temperature cycling essentially lead to thermal fatigue process at Ag/Au interface, therefore more serious interface strength degradation is generated by larger temperature cycling range. Joint failure is initiated by thermal fatigue induced dislocation and residual strain concentrations around dissimilar interface. And the large mismatch in coefficients of thermal expansion (CTE) of the multilayer structure amplifies the thermal fatigue effect.

Effect of coping materials zirconia or polyetheretherketone with different techniques of fabrication on vertical marginal gap and fracture resistance of posterior crowns with composite veneering

BackgroundInsufficient research has been conducted in the literature assessing the performance of zirconia and polyetheretherketone (PEEK) crowns in relation to the essential requirements of successful restorations, such as fracture resistance or margin adaptation. The purpose of this study was to evaluate the effect of the coping materials zirconia or PEEK with different fabrication techniques on the vertical marginal gap and fracture resistance of posterior crowns with composite veneering.MethodsCeramic copings (n = 18) restoring mandibular first molar were fabricated from zirconia (Zircon.x, Presidentdental, Germany), milled PEEK (PEEK CAD) (breCAM.BioHPP, Bredent, Germany) and pressed PEEK (PEEK Press) (BioHPP Granules, Bredent, Germany) six specimens each (n = 6). The copings were veneered with high impact polymer composite (HIPC) material (breCAM.HIPC, Bredent, Germany). The vertical marginal gap was captured under a magnification of 40X. Five equidistant marks on each surface of the die distinguished the points of measurement for a total of 20 readings per sample. The analysis was completed using an image analysis system (ImageJ 1.53t, National Institute of Health, USA). The specimens were loaded to failure at a crosshead speed of 1 mm/min and the load at failure was recorded to measure the fracture resistance.ResultsThe marginal gap was analyzed using one-way ANOVA followed by Tukey’s post hoc test. Fracture resistance was analyzed using Welch one-way ANOVA followed by the Games-Howell post hoc test. Marginal gap values showed a significant difference between the tested groups, with zirconia having significantly lower gap values (48.67 ± 11.98 µm) than both the PEEK CAD (108.00 ± 20.08 µm) and Press groups (108.00 ± 25.10 µm) (p < 0.001). However, the results of fracture resistance showed no significant difference (p = 0.06) with 1687.47 ± 253.29 N, 2156.82 ± 407.64 N, 2436.72 ± 725.93 N for zirconia, PEEK CAD, and Press, respectively. The significance level was p < 0.05.ConclusionsZirconia framework crowns have a smaller vertical marginal gap than milled and pressed PEEK crowns. Crowns fabricated from zirconia, PEEK CAD, or PEEK Press frameworks and veneered with composite resin have comparable fracture resistance lower than the maximum biting force in the posterior region.Clinical relevancePosterior crowns with zirconia frameworks are preferred over milled and pressed PEEK frameworks regarding margin adaptation, although all can safely survive the maximum occlusal forces without fracture.

Effect of loading speed on gap resistance and tensile strength of flexor tendon repair under cyclic loading test

Postoperative digit motion is important for the functional recovery of injured tendons. To date, it is unknown whether the loading speed impacts the biomechanical properties of a repaired tendon. This study investigated the effect of loading speed on the gap resistance and tensile strength of tendon repairs. One hundred porcine flexor tendons were repaired with two core sutures, 4-strand modified Kessler and double Q, and cyclically loaded at the speeds of 10, 40, 80, 160, and 320 mm/min. The number of tendons that formed an initial or 2 mm gap at the repair site during cyclic loading, stiffness at the 1st and 20th loading cycles, gap size between tendon ends when cyclic loading ended, and the ultimate strength were recorded. Under the lowest loading speed, the tendons repaired with the 4-strand modified Kessler suture developed significantly larger gaps and smaller stiffness than those with a greater loading speed. The loading speed did not affect the maximum strength of both tendon repairs. The findings suggest that very slow motion promotes gap formation of tendon repair with inferior gap resistance. The rate corresponds to regular hand action or the tendon core suture possessing a strong gap resistance increases the safety margin during early active finger movement. Our findings help to guide the exercise regimens after tendon surgery.

Joining mechanism of connection between Ag-plated Kovar interconnector and stranded Ag-plated Cu wire produced via parallel gap resistance welding

A space solar array includes GaAs solar cell, interconnector, and stranded Cu wire. Due to the preferential high working efficiency, the assembly of solar array is mostly performed using parallel gap resistance welding (PGRW). Since strengthening of the PGRW joints is the key to further extend service life of solar array, it is necessary to elucidate joining mechanism of each connection. In the present research, to clarify the controversy over PGRW joining mechanism between Ag-plated Kovar interconnector and stranded Ag-plated Cu wire, various advanced material characterization methods are conducted to joining interfaces. Experimental results confirm that, in addition to the known Ag/Cu eutectic interface, solid evidence of metallurgy bonding is also found in Cu/Cu interface. Such finding has significant implication for further enlarge the PGRW process window and produce stronger joints.

A comprehensive study of parallel gap resistance welding joint between Ag foil and front electrode of GaAs solar cell

When space solar cell array is subjected to harsh temperature cycle, such as planet orbit, thermal fatigue cracks in bonding area are easily induced. With the aim of improving bonding quality and elucidating failure mechanism of parallel gap resistance welding (PGRW) joints in temperature cycling environment, the present research investigates the effect of current density on bonding quality and thermal fatigue behavior of PGRW joint between Ag interconnector and front electrode of GaAs solar cell. When current density is set at 417 A/mm2, a solid diffusion bonding is achieved at the Ag/Au interface, which also possesses adequate joint strength as ensured by both pressure and input energy of PGRW. Crack initiation by thermal fatigue is found at joint edge, which subsequently propagates along the interface as the environment temperature cycling continues. Further investigation reveals that the conducted temperature cycling generates serious tensile and compressive stress in the multi-layered joint structure. Since such reciprocating forces directly induce micro-plastic deformation and strain accumulation at joint interface, failure by crack is finally generated at the joining interface.

Influence of the direction of suture strands on the tensile strength after flexor tendon repairs.

We assessed the influence of different directions of suture strands using the double Tsuge repair on the resistance to gap formation and mode of failure. In total, 25 porcine flexor digitorum profundus tendons were split into two groups. One group was repaired using a conventional double Tsuge suture created by two bands of looped suture placed longitudinally parallel (parallel method), and the other group was repaired using a new technique comprising two bands of looped suture placed in a crossed fashion in the anterior and posterior half of the tendon (cruciate method). The repaired tendons were subjected to linear, non-cyclic load-to-failure tensile testing. The cruciate method had a significantly higher mean load at a 2-mm gap tensile load (29.7 N [SD, 8.3]) than the parallel method (21.6 N [SD, 4.9]) and failed significantly more often due to suture pull-out. The direction of a core suture and its location within the tendon affect both gap resistance and the mode of failure of repair when using the double Tsuge suture technique, with a cruciate configuration achieving a greater gap resistance than a parallel one.

An improved resistance model of positive subsonic plasma channels in water

The subsonic plasma channel and water can be regarded as series resistors in the pre-breakdown stage of sub-millisecond pulsed discharge in conductive water. An improved resistance model of the positive subsonic plasma channel is proposed. The gap resistance and the morphology of the bubble cluster and the plasma channel inside it are obtained from the electrical measurement and optical observation, respectively. The resistance of the plasma channel in the strong-ionization stage is calculated using the small-current arc resistance model. The improved model of the water resistance is established by analyzing the relationship between its equivalent cross-sectional area and its length in an uneven electric field. The resistance of the plasma channel in the weak-ionization stage is calculated. The resistance, voltage, and energy in the gap are analyzed based on the improved resistance model. The plasma channel's resistance is far less than the water resistance. The low voltage drop in the plasma channel leads to a high electric potential in the plasma channel's head, which is conducive to the plasma channel's development. 97% of the total energy in the pre-breakdown stage is consumed by the water resistor. The improved resistance model is helpful to supplement the development mechanism of the sub-millisecond pulsed discharge in water.

Stabilization of Component-Pure α-FAPbI3 via Volatile Additives for Stable Photovoltaics

State-of-the-art high-performance perovskite solar cells are mainly based on formamidinium (FA)-dominated perovskites because of their narrow band gap and remarkable thermal resistance. However, photoactive α-FAPbI3 is prone to transit to the photoinactive phase, and pioneering phase stabilization strategies can induce undesirable band gap broadening or phase segregation, seriously restricting the efficiency and long-term stability of the resultant photovoltaics. Herein, a small molecule of ammonium acetate (NH4Ac) was introduced as an additive in a modified ripening method to fabricate component-pure α-FAPbI3. Owing to the strong interaction between NH4Ac and PbI2, FAI via Pb-O coordination, and N-H···N hydrogen bonding, vertically oriented perovskites with relaxed crystal strain were first generated, which were fully converted to α-FAPbI3 in a further ripening process. The NH4Ac was fully volatized after the perovskite formation, resulting in component-pure α-FAPbI3 with a band gap of 1.48 eV and remarkable stability under light illumination. Ultimately, a champion device efficiency of above 21% was obtained based on the component-pure α-FAPbI3 and over 95% of the initial efficiency can be maintained after 1000 h of aging.

Effect of pre-welding and welding voltage on thermal fatigue property of parallel gap resistance welded joint between Ag interconnector and Au/Ag back electrode of GaAs solar cell

Thermal reliability of Au/Ag interconnection is a crucial factor for the life of solar cell array during service in space. Although it is known that increasing the heat input can effectively improve the joint thermal fatigue resistance, such welding energy increase has to be achieved by coordination of various parameters to avoid damage to the solar cell matrix. Therefore, clarification of specific strengthening mechanism by different welding parameter is significant for the further improvement of joining quality. In this study, parallel gap resistance welding (PGRW) is used to perform micro-leveled interconnection between Au/Ag back electrode of triple-junction GaAs space solar cell and Ag interconnector. Besides the original parameter set, methods of welding voltage increase and pre-welding are used to improve the joining quality. Subsequently, the samples are subjected to temperature cycling environment between−160 °C and+120 °C for various cycles. According to the tensile-shear test results, although both methods have effectively improved the joint thermal fatigue property, quite different strengthening routes are shown. On one hand, joints strengthened by increasing welding voltage have higher tensile shear force than the ones strengthened by pre-welding. On the other hand, joints optimized by pre-welding show much stabler tensile-shear property. Material characterization by transmission electron microscopy (TEM) has explained the different strengthening routes that increase of voltage actually changes the joining mechanism from original solid-phase diffusion between Au/Ag interface into total melting, while pre-welding keeps the interface with partial solid-phase diffusion interface. Besides, electron back scattered diffraction (EBSD) results indicate that the evolution of residual stress concentration is the intrinsic reason for thermal fatigue failure of the Au/Ag interface.

SnO2: rGO transparent semiconducting thin films under annealing by hydrazine—modification of optical gap and electrical resistance

SnO2: rGO transparent semiconducting thin films under annealing by hydrazine—modification of optical gap and electrical resistance

Machine learning analysis on critical structural factors of Al:ZnO (AZO) films

Machine learning (ML) has been recently approved to generalize materials design insights from many narrow-scoped individual experiments. In this study, decision tree algorithm (DT) was able to clarify critical structural factors enabling Al-doped ZnO (AZO) films with wider (or narrower) energy band gap and higher (or lower) electrical resistivity on published literature data as well as having ∼90 % average prediction accuracy. Cost-effective alternative of expensive physical models and simulations to reveal promising AZO films before physical experiments. Trained DTs were interpreted to uncover critical design insights. It was concluded that all microstructural features (crystalline size, crystallinity, dislocation density and interlamellar spacing) should be considered simultaneously through a holistic perspective in a design proposal. Al doping concentration and film thickness, as charge carrier contributors, were found as critical features for band gap and electrical resistivity, respectively. Effects on microstructural features should be considered as well as prerequisite in film design because of complex crystal growth mechanism.

Solution-Processable PEDOT Particles for Coatings of Untreated 3D-Printed Thermoplastics

Lack of solution processability is the main bottleneck in research progression and commercialization of conducting polymers. The current strategy of employing a water-soluble dopant (such as PEDOT:PSS) is not feasible with organic solvents, thus limiting compatibility on hydrophobic surfaces, such as three-dimensional (3D) printable thermoplastics. In this article, we utilize a colloidal dispersion of PEDOT particles to overcome this limitation and formulate an organic paint demonstrating conformal coating on 3D-printed objects. We start with synthesizing PEDOT particles that possess a low electrical resistance (gap resistance of 4.2 ± 0.5 Ω/mm). A particle-based organic paint is formulated and applied via brush painting. Coated objects show a surface resistance of 1 kΩ/cm, comparable to an object printed by commercial conductive filaments. The coating enables the fabrication of pH and strain sensors. Highly conductive PEDOT particles also absorb light strongly, especially in the near-infrared (NIR) range due to the high concentration of charge carriers on the polymer's conjugated backbones (i.e., polarons and bipolarons). PEDOT converts light to heat efficiently, resulting in a superior photothermal activity that is demonstrated by the flash ignition of a particle-impregnated cotton ball. Consequently, painted 3D prints are highly effective in converting NIR light to heat, and a 5 s exposure to a NIR laser (808 nm, 0.8 mW/cm2) leads to a record high-temperature increase (194.5 °C) among PEDOT-based coatings.

High-temperature ultrafast welding creating favorable V2O5 and conductive agents interface for high specific energy thermal batteries

The high interfacial resistance between V 2 O 5 cathode materials and conductive agents (molten salt and super carbon) is one of the biggest issues that hinder the development of high specific energy thermal batteries. Designing fast Li + and e – transport channels in cathode electrodes is considered as an effect method to improve electrochemical performance. Hence, a high-temperature ultrafast welding is proposed to reduce V 2 O 5 /conductive agents interfacial resistance by reconstructing the transmission channels of Li + and e – in this paper. The experimental studies reveal the optimum ultrafast welding of 700 °C for 10 s, eliminating gap resistance of cathode electrodes induced by the melt of solid molten salt and rebuilding the more plentiful Li + and e – transport channels, further reducing the contact resistance and gap resistance. Therefore, the electrodes deliver a high specific capacity of 270.69 mAh g −1 and a high specific energy of 610.60 Wh kg −1 at 0.1 A cm −2 and 500 °C with a cut-off voltage of 1.6 V. The high-temperature ultrafast welding provides guidance to build Li + and e – transport channels of other cathode materials in thermal batteries.

Robust LiDAR-Camera Alignment With Modality Adapted Local-to-Global Representation

LiDAR-Camera alignment (LCA) is an important preprocessing procedure for fusing LiDAR and camera data. For it, one key issue is to extract unified cross-modality representation for characterizing the heterogeneous LiDAR and camera data effectively and robustly. The main challenge is to resist the modality gap and visual data degradation during feature learning, while still maintaining strong representative power. To address this, a novel modality adapted local-to-global representation learning method is proposed. The research efforts are paid in 2 main folders via modality adaptation and capturing global spatial context. First for modality gap resistance, LiDAR and camera data is projected into the same depth map domain for unified representation learning. Particularly, LiDAR data is converted to depth map according to pre-acquired extrinsic parameters. Thanks to the recent advantage of deep learning based monocular depth estimation, camera data is transformed into depth map in data driven manner, which is jointly optimized with LCA. Secondly to capture global spatial context, ViT (vision transformer) is introduced to LCA. The concept of LCA token is proposed for aggregating the local spatial patterns to form global spatial representation with transformer encoding. And, it is shared by all the samples. In this way, it can involve global sample-level information to leverage generalization ability. The experiments on KITTI dataset verify superiority of our proposition. Furthermore, the proposed approach is more robust to camera data degeneration (e.g., imaging blurring and noise) often faced by the practical applications. Under some challenging test cases, the performance advancement of our method is over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.9~cm$ </tex-math></inline-formula> /4.1° on translation / rotation error. While our model size (8.77M) is much smaller than existing methods (e.g., LCCNet of 66.75M). The source code will be released at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://github.com/Zaf233/RLCA</uri> upon acceptance.

Joining mechanism of parallel gap resistance welded dissimilar connection between Ag interconnector and GaAs solar cell: A transmission electron microscopy study

Quality of connections between solar cells directly influences the life of a spacecraft in complex space environment, which thus makes clarification of joining mechanism between interconnector and solar cell electrode by certain method a necessity for further quality improvement of solar array. In the present research, the connection between Ag interconnector and GaAs solar cell is performed using parallel gap resistance welding (PGRW) under a set of appropriate parameters to achieve optimal bonding that possesses adequate strength without degrading photoelectric property of cell. To characterize the microstructure and element distribution at interface in detail, advanced transmission electron microscopy (TEM) was conducted. According to the obtained results, the PGRW interface between Ag interconnector and Au plated Ag electrode of GaAs solar cell shows a solid-solution phenomenon via element diffusion. Also, under the compressive force and thermal input during PGRW, twins are found originating along the grain boundary from Ag interconnector into Ag layer of GaAs solar cell crossing the Au surface. The characterization findings have confirmed the capability of achieving solid-state diffusion connection by PGRW.

Effect of Na doping and heat treatment on the characteristics of ZnO thin films and ZnO/Si cells

• Undoped and Na doped ZnO films and ZnO/Si cells fabricated by chemical spray pyrolysis. • Band gap energy and resistivity of ZnO thin films decreased with Na doping and thermal annealing. • Power conversion efficiency of ZnO/Si heterojunction cell remarkably increased with Na doping and thermal annealing. Undoped and sodium doped ZnO thin films were grown on glass and Si substrates by spray pyrolysis. Post thermal annealing was applied for 1 h at 350 °C. Effect of Na doping and thermal annealing on the properties of ZnO thin films were investigated via XRD, UV–Visible spectrometry and resistivity measurements. Resistivity of the Na doped and annealed ZnO film was decreased to 7.15x10 3 Ω.cm from 3.26x10 4 Ω.cm where band gap energy was decreased to 3.31 eV from 3.36 eV. Current-voltage measurements held for all ZnO/Si heterostructures in dark and under illumination and device parameters were determined. Again best result obtained for the device in which both Na doping and annealing were applied as efficiency was increased to 4.57% from 2.01%.

Boosting the charge transfer kinetics in MOCVD prepared nitrogen doped hierarchical ZnO-Si nanowires for bifunctional photoelectrochemical water oxidation and organic contaminant removal

Zinc oxide nanowires (ZnO NWs) are emerging as a promising photocatalyst for photoelectrochemical (PEC) energy generation and environmental remediation owing to their fascinating properties. However, a relatively wide band gap and low resistance to photo-corrosion limit their PEC activity. In this context, we report a rational strategy to fabricate hierarchical ZnO NWs on Si NWs (ZnO-Si NWs) via metal organic chemical vapor deposition (MOCVD) with nitrogen (N)-doping to alleviate the intrinsic drawbacks. The N-doped ZnO-Si NWs (N:ZnO-Si NWs) showed excellent light harvesting and efficient charge separation which boosted the PEC activities as compared with ZnO NWs. The fabricated photoanodes were examined for PEC water splitting and remediation of textile industry dye. N:ZnO-Si NWs exhibited 357 μA cm−2 photocurrent density (at 1.0 V vs Ag/AgCl) which was 3-fold higher than bare ZnO-Si NWs. In addition, N:ZnO-Si NW photoanodes showed remarkable PEC efficiency of 95 % toward methylene blue (MB) dye removal under AM 1.5 G illumination with 4 times reusability. These findings provide an efficient approach to developing a novel fabrication strategy for the construction of bifunctional PEC devices with exceptional water splitting and dye degradation efficiencies.