Step Profile Research Articles

A novel breath pattern model and analysis to minimize patient discomfort in medical ventilators

Typical waveforms used for the simulation of pressure and volume-controlled ventilation in medical ventilators have been extensively studied in the literature. The majority of simulation studies reported employ the step pattern or ramp pattern to model the pressure and flow variations in pressure/volume-controlled ventilation. It was observed that the above waveforms tend to add to the discomfort level of patients due to the presence of jerks in derivatives of pressure/flow variations; the pressure/flow variation of air and oxygen mixture should be smooth so that the patient discomfort is kept at a minimal level. To overcome the above-mentioned drawback, a careful study of the flow/pressure simulation using a cycloidal pattern during the inhalation and exhalation phases of the breath cycle was proposed and investigated in this work. Based on transient analysis of the pressure variation simulation, it was observed that the air and oxygen mixture delivered to the patient was relatively jerk-free due to the finite values of first and second-order derivatives of pressure/flow curves. Mathematical models of the proposed simulation study of the cycloidal pattern of flow variation in both pressure/volume-controlled ventilation, are formulated and presented for use by ventilator designers. A comparative study of the simulation of step, ramp and cycloidal profiles applied to the breath cycle in a typical pressure-controlled ventilation is carried out and a marginal decrease in tidal volumes was observed in the case of cycloidal profiles for a given set of ventilator settings and the results are discussed. A typical natural breath pattern of a healthy adult was experimentally measured using a CITRIX breath analyser and the above mathematical model for the volume-controlled ventilation was found to closely describe the natural breathing process, using statistical parameters. Thus, the proposed cycloidal profile of pressure/flow variations in medical ventilators will be a better alternative, when compared to the step/ramp profiles investigated in this work; further, the proposed cycloidal profile matches closely with the natural breath pattern, based on typical experimental studies.

Deciphering the Complexity of Step Profiles on Vicinal Si(001) Surfaces Through Multiscale Simulations.

The behavior of vicinal Si(001) surfaces are a subject of intense research for years, yet the mechanism behind its step modulation remains unresolved. Step B, in particular, can meander randomly or form a periodic zigzag profile, a surface phenomenon that has eluded explanation due to the lack of appropriate simulation tools. Here, a multiscale simulation strategy, enhanced by machine learning potentials are proposed, to investigate this mesoscale behavior. The study reveals a phase transition in the step profile on vicinal Si(001) surfaces from random meandering to a zigzag wave pattern as the miscut angle decreases. This step-profile transition is corroborated by Monte Carlo simulations and experimental observations. Remarkably, this transition is robust across various surface conditions, including bare, hydrogen-saturated, boron-doped, or strained surfaces. The findings resolve the long-standing puzzle of step polymorphism on vicinal Si(001) surfaces and pave the way for exploring mesoscale phenomena using multiscale simulations.

Negative capacitance source pocket double gate tunnel FET as a label-free dielectrically modulated biosensor

Abstract This article examines the potential use of Negative Capacitance Source Pocket Double Gate Tunnel Field Effect Transistor (NC-SP-DGTFET) as a biosensor capable of detecting the biomolecules present in the nanocavity. The proposed biosensor incorporated a gate dielectric engineering along with the channel engineering method and asymmetrical doping at source and drain regions. In addition, a nanocavity is formed by selectively removing a section of the gate dielectric at the source and drain ends to accompany the biomolecules in the device. The biosensing performance measures Threshold Voltage Sensitivity (S_(V_th )), ION/IOFF Current Ratio Sensitivity (S_(I_oN/I_OFF )), and Drain Current Sensitivity (S_(I_DS )), with 60.3, 372.3, and 395.4 respectively are observed with neutral charge of biomolecules. The investigation involves biomolecules with positive and negative charges, which are tested under different dielectric constants in the nanocavity. In addition, an extensive investigation of a partially filled nanocavity caused by steric hindrance has been presented to capture the current situation. The study examined several scenarios with partially filled nanocavities to analyze the sensitivity characteristics, including convex, concave, increasing, and decreasing step profiles, as well as the positioning of the probe in an asymmetric manner. The study compares several sensitivity characteristics of the NC-SP-DGTFET with existing biosensors to determine the effectiveness of the proposed biosensor. The NC-SP-DGTFET biosensor outperforms traditional TFET-based biosensors by using a ferroelectric material as the oxide material. This choice of material enhances the subthreshold slope, increases gate control over the channel, and demonstrates its suitability for low-power biosensor design.

Direct prediction of saturated neoclassical tearing modes in slab using an equilibrium approach

Abstract We demonstrate for the first time that the nonlinear saturation of neoclassical tearing modes (NTMs) can be found directly using a variational principle based on Taylor relaxation, without needing to simulate the intermediate, resistivity-dependent dynamics. As in previous investigations of classical tearing mode saturation (Loizu et al 2020 Phys. Plasmas 27 070701; Loizu and Bonfiglio 2023 J. Plasma Phys. 89 905890507), we make use of Stepped Pressure Equilibrium Code (SPEC) (Hudson et al 2012 Phys. Plasmas 19 112502), an equilibrium solver based on the variational principle of the multi-region relaxed magnetohydrodynamics (MHDs), featuring stepped pressure profiles and arbitrary magnetic topology. We work in slab geometry and employ a simple bootstrap current model J bs = C ∇ p to study the bootstrap-driven tearing modes, scanning over the asymptotic matching parameter Δ ′ and bootstrap current strength. Saturated island widths produced by SPEC agree well with the predictions of an initial value resistive MHDs code (Huang and Bhattacharjee 2016 Astrophys. J. 818 20) while being orders of magnitude faster to calculate. Additionally, we observe good agreement with a simple analytical modified Rutherford equation, without requiring any fitting coefficients. The match is obtained for both linearly unstable classical tearing modes in the presence of bootstrap current, and NTMs, which are linearly stable but nonlinear-unstable due to the effects of the bootstrap current.

Design of Experiment and green analytical chemistry principles for developing a robust and sustainable Stability-Indicating HPLC method for Bempedoic acid impurity profiling

Bempedoic acid (BEM), a drug used to lower cholesterol levels in patients with atherosclerosis. Controlling its process-related impurities is crucial due to their potential toxicity. This study details the development of a RP-HPLC method for the analysis of four process-related substances in BEM. To ensure robust chromatographic performance meeting six sigma quality standards, the method was optimized using a combined approach of response surface methodology (specifically, an I-optimal design) and tolerance analysis, integrating predefined specifications for critical method attributes such as resolution, tailing factor, and number of theoretical plates into the developmental process. Chromatographic separation was achieved using a C18 column. The mobile phase consisted of 0.1 % phosphoric acid in water and acetonitrile, utilizing a stepped gradient elution profile. The flow rate was maintained at 0.9 mL/min, with UV detection performed at 210 nm. The column temperature was set to 20 °C. The method demonstrated linearity for BEM process related impurities in the range of LOQ to 30 μg mL−1. The method ability to differentiate the drug substance from its degradation products was confirmed through forced degradation study. The environmental sustainability of the developed method was assessed using multiple Green Analytical Chemistry (GAC) tools. The National Environmental Methods Index (NEMI) showed two green-shaded quadrants, and the Green Certificate modified Eco-scale awarded a score of 70. The Complementary Green Analytical Procedure Index (Complex GAPI) confirmed the method environmentally friendly profile. Additionally, The AGREE tool generated a score of 0.77, indicating strong overall greenness, while the AGREEprep tool, focused on sample preparation, yielded a score of 0.54. Other tools such as the Sample Preparation Metric of Sustainability (SPMS) and the HPLC Environmental Assessment Tool (HPLC-EAT) scored 8.42 and 569, respectively, further demonstrating the method green credentials. This robust and environmentally conscious analytical framework offers significant potential for application in quality control of BEM.

Performance assessment of SiGe extended four corner source TFET for biosensing applications

In this paper, the performance of a novel SiGe extended four corner source tunneling field–effect transistor (SiGe EFCS TFET) based dielectrically modulated label-free biosensor has been investigated for biosensing applications. Using a combination of heterostructure (SiGe/Si) and extended four corner source (EFCS) lead to increased band–to–band tunneling (BTBT) probability, improved gate control and superior drain current sensitivity for biomolecule conjugation in comparison with a conventional TFET and Si EFCS TFET structures of similar dimensions. The influence of both the charge–neutral and charged biomolecules on the sensitivity performance is investigated using the Silvaco TCAD ATLAS semiconductor device simulator with a calibrated nonlocal BTBT model. Four different kinds of biomolecules such as Streptavidin, Ferro–cytochrome c, Keratin and Gelatin with various charge density values were used for this purpose. In order to model steric hindrance effects in partially filled cavities, in addition to various fill factors, four different step profile patterns have considered such as convex, concave, decreasing and increasing step profiles. Also, the dependence of the nanogap cavity properties on the sensing performance in terms of the length and thickness is investigated. A maximum drain current sensitivity of 1.69 × 105 is achieved in SiGe EFCS TFET for Gelatin biomolecules in a fully filled nanogap cavity at overdrive and drain voltages of 0.5 V.

Intrinsic reactivity of stoichiometric IrO2(1 1 0) surface toward oxidative coupling of methane

This study investigates the oxidative coupling of methane on the IrO2(110) surface using TPRS simulations informed by DFT-derived data. We discover that the efficiency of the IrO2(110) surface in generating ethylene is strongly influenced by methane surface coverage. Our simulations reveal that the presence of surface hydroxyl group enhances the yield of C2+ species from methane oxidation, but this effect is counteracted at high methane coverages due to the accelerated formation of CH2OH. In addition, the study reveals that slight modifications in energy barriers at the branching point (C2H4 formation vs. CH2OH formation) significantly affect C2H4(g) production from the simulation, underscoring the importance of precise energetic data for accurate catalytic reaction predictions. The results have broader implications for reactions and catalysts where branching point selectivity determines high-value product yields. Thus, combining surface science with computational analysis is crucial for accurately determining energy profiles of key steps at the branching points.

Effect of underwater relief on the dynamics of the autumnal thermal bar

Through numerical modelling techniques, data were obtained on how underwater slopes influence the dynamics of a thermal bar and the related circulations during the water body’s autumn cooling. Different geometries of the bottom topography were analyzed, aligning with configurations such as «gentle slope», «stepped profile», «trench», and «steep slope». It was determined that in the autumn, the flow structure, the formation timeframes, and the thermal bar propagation speed are significantly influenced by the morphological features of the lake bottom.

Low-profile dielectric grooved GRIN lens for broadband millimeter-wave applications

Microwave lenses are utilized at millimeter waves to ensure high-gain and narrow-beamwidth radiation patterns. This paper proposes full-dielectric grooved graded-index (GRIN) lenses with an improved effective permittivity profile of the lens. The proposed grooved GRIN lenses combine changes in the lens geometry with the stepped effective permittivity profile to better approximate the theoretical permittivity profile of the lens. A prototype GRIN lens has been designed, fabricated, and measured. The designed lens has diameter and thickness equal to 72 mm and 19.04 mm (5.3λ0, 1.4λ0 at the center frequency of 22 GHz), respectively. The lens covers the entire K-band (18–26.5 GHz) with aperture efficiency better than 44%. Moreover, it achieves the maximum gain and aperture efficiency of 23 dBi and 64%, respectively.

Expanding the dose window of step-etched space-modulated JTE for ultrahigh voltage 4H-SiC devices

A step-etched space-modulated junction termination extension (SE-SM-JTE) is proposed for ultrahigh voltage (≥10 kV) 4H-SiC devices in this work. The proposed structure creates a stepped effective JTE dose profile by introducing the step etching into space-modulated JTE (SM-JTE), which shows great merits in the compromises of the JTE dose window, termination efficiency, termination area, and the complexity of the fabrication process. According to the TCAD simulation results, the SE-SM-JTE with a length of 300 μm (3 times the drift layer thickness) obtains a wide implantation dose window of ±47 % above 12 kV, achieving a wide tolerance to JTE dose and surface fixed charge. The maximum breakdown voltage (BV) of the proposed SE-SM-JTE is 13.8 kV, exhibiting a termination efficiency of 92 %. Moreover, the proposed JTE structure requires only a single ion implantation and subsequent two etchings, which facilitates the fabrication feasibility in ultrahigh voltage 4H-SiC devices.

Displacement versus velocity memory effects from a gravitational plane wave

This article demonstrates that additionally to the well-known velocity memory effect, a vacuum gravitational plane wave can also induce a displacement memory on a couple of test particles. A complete classification of the conditions under which a velocity or a displacement memory effect occur is established. These conditions depend both the initial conditions of the relative motion and on the wave profile. The two cases where the wave admits a pulse or a step profile are treated. Our analytical expressions are then compared to numerical integrations to exhibit either a velocity or a displacement memory, in the case of these two families of profiles. Additionally to this classification, the existence of a new symmetry of polarized vacuum gravitational plane wave under Möbius reparametrization of the null time is demonstrated. Finally, we discuss the resolution of the geodesic deviation equation by means of the underlying symmetries of vacuum gravitational plane wave.

Stability Analysis of the Secondary Motion of a Textured Piston

Piston–cylinder pairs are very common in industrial mechanisms. While a piston is primarily designed for axial reciprocating motion, the occurrence of secondary motions—lateral and rotational—due to the small clearance between the piston and the cylinder may lead to frictional contact, energy loss, wear and an increase in unwanted leakage. This study focuses on mitigating the secondary motion of a ringless piston. The influence of a Rayleigh step bearing and partial surface texturing with numerous micro-dimples on the dynamic stability of the secondary motion is studied. A linear model was used to obtain the trajectory of the secondary motion and Floquet theory was applied to analyze the stability and draw stability maps. The influence of various texturing and step parameters, including the dimple area density and aspect ratio for partial texturing, as well as the length and depth of treatment for both partial texturing and step profiles, on the stability of the secondary motion was examined. The normalization method is presented, enabling the expansion of the results for various operating conditions and geometries. Conclusions and guidelines regarding the optimal parameters, in terms of a wider stability range and higher decay rate, are formulated.

Thermal vibration analysis of bi-directionally stepped porous functionally graded plates with segment-specific material property variation supported by Kerr foundation

This paper presents a comprehensive analysis of the nonlinear dynamic response of stepped rectangular plates made of functionally graded porous material (FGPM), supported by the Kerr foundation, in a thermal environment. A novel analytical framework is developed to explore geometric and material variations. The study investigates structural variations in plate thickness with abrupt changes in uni- or bi-directional orientations, examining both single and double stepped thickness profiles. Material properties vary with thickness, featuring distinct horizontal discontinuities across plate segments. Porosity distributions, both even and uneven, are addressed using modified mixture rules. Nonlinear kinematic relationships are established using Reddy’s third-order shear deformation plate theory and von Kármán’s nonlinear geometric assumptions, with equations of motion solved via Galerkin’s technique. This improved model effectively addresses non-continuous thickness variation through integral calculus, enhancing computational efficiency. Validation is achieved by comparing outcomes with published literature and Finite Element Analysis (FEA). The study investigates the influence of material properties, elastic foundation, boundary conditions, and geometric parameters on the free vibration and nonlinear behaviors of the plates. Some of the key findings include: increasing the thickness of the stepped segment significantly heightens the fundamental frequency while reducing vibrational amplitudes; optimizing the location of the stepped segment directly impacts the plate’s fundamental frequency and vibrational amplitudes; and as the load factor increases, the difference between linear and nonlinear deflection becomes evident. Therefore, accurate FGPM stepped plate design requires incorporating nonlinear terms in the strain–displacement relationships. Suggestions for future model modifications are also discussed, contributing to advancements in structural design and analysis.

Bat thermoregulation in the heat: seasonal variation in evaporative cooling capacities in four species of European bats

Phenotypic flexibility is an important source of physiological variation in endotherms and plays an integral role in species’ response to rapid environmental changes. Studies of phenotypic flexibility have focused on winter acclimatization and cold endurance, and there are fewer data on summer acclimatization and adjustments in heat dissipation capacity, especially in Temperate-Zone species. We used indirect calorimetry and thermometry to test if thermoregulation at high air temperatures (Ta) varies between spring and summer in four species of European vespertilionid bats: Nyctalus noctula, Pipistrellus nathusii, P. pygmaeus, and P. pipistrellus. We measured subcutaneous body temperature (Tsub), evaporative water loss, and resting metabolic rate while exposing bats to a stepped profile of increasing Ta, from 28 °C–48 °C. We predicted that during summer, bats increase heat tolerance and evaporative cooling capacity, to better tolerate hotter Tas. In contrast, we found lower maximum ratios of evaporative heat loss (EHL) to metabolic heat production (MHP) during summer, but no seasonal differences in maximum Ta tolerated or Tsub. The main cause of this seasonal difference in maximum EHL/MHP seems to be from bats increasing EWL more gradually with increasing Ta in summer than spring, particularly in the smaller Pipistrellus species. Therefore, this seasonal variation in heat-dissipation strategies may reflect enhanced water conservation during summer to avoid dehydration, as bats are confined to roosts for longer and hotter days compared to spring.

Эколого-биологические методы формирования устойчивых лесомелиоративных комплексов в степных и полупустынных ландшафтах европейской территории России

The arid region of the European territory of Russia includes a zone of dry steppe (dark chestnut soils) and a semi-desert zone (light chestnut and brown soils). There is practically no woody natural vegetation in the region on elevations and plains, and on the prevailing complexes of zonal soils, forest plantations are characterized by low durability. Materials and methods. The work used the results of field (expedition) and laboratory studies of the growth, condition, durability, productivity of protective forest plantations of tree and shrub species in various soil and hydrological conditions of the dry-steppe and semi desert zones. Results and discussion. The author’s developments made it possible to recommend a reliable range of trees and shrubs for the creation of forest-reclamation plantations in each agroforestry area and soil ecological niche. It was revealed that when selecting the assortment, a significant role should be given to selection and genetic methods of using seed and planting material well adapted to local conditions (drought-, salt- and frost-resistant and healthy genotypes). The main reason for the early drying of protective plantations on complex light chestnut soils of the dry-steppe and semi-desert zones has been established. Taking into account the extremely arid conditions and the main causes of their drying, the concept of increasing their stability and effectiveness in adverse growing conditions is given. Agroforestry zoning and groups of soil forest suitability by type and classification, as well as groups of longevity of the main tree species are given. Conclusion. The large diversity of soils contributes to the formation of a stepped profile in adult cereals. Woody species shrink when their root system comes into contact with salt horizons. Ecological techniques are reduced to the correct selection of tree species that correspond to a specific ecological background. The technological use of differentiated agricultural cultivation techniques involves the use of moisture-saving technologies. Biological measures include biological reclamation of unsuitable soils and methods of breeding and genetic improvement of the qualitative composition of forest reclamation plantations. Suggestions for practical applications and directions for future research. The results of the work can be used by managers and specialists of forestry enterprises, researchers, graduate students, students of educational institutions. The assortment of trees and shrubs can be used in the design of plantings of various types on different soils.

A soil base model of adjacent various story structures

In modern geotechnical engineering, owing to the development of information technology and availability of powerful packages for the calculation of the entire base - foundation - structure system, one of the main research areas is to develop, improve and investigate soil base models to ensure the adequate interaction between the components of the system during the construction and operation of buildings and structures (hereinafter referred to as the “structures”). The paper proposes an improved soil base model in the form of a continuous layer of finite distribution capability to simulate and calculate adjacent multistory structures in the base - foundations - structures system using powerful calculation packages such as SOFiSTiK, ABAQUS, PLAXIS, SCAD, Lira and others. The improved model considers the parameters of the stress-strain properties of the soils of the bases, the geometric profile taking account of the distribution capability of the base and different boundary conditions, but differs from the existing models in that it has a stepped geometric profile at the lower boundary of the model because of different compressible layer depths under each foundation of the structures. The use of this model improves the accuracy of simulating a soil base for large-sized foundations of adjacent structures to obtain reliable results of the stress-strain state of the base - foundations - structures system. An example demonstrates how to simulate and calculate raft foundations of a two-section multistory building in the base - foundations - structures system that interacts with an improved soil base model (linear strains of soils under loads are considered here) with reference to different numbers of stories of the sections. The numerical study results show on a specific calculation example that considering different compressible layers depths in the model under differently loaded foundations results in an increase in moment forces of up to 65% as compared with simulating the whole compressible layer, which may lead to the disruption of large-sized raft foundations.

Adhesive-free bonding for hetero-integration of InP based coupons micro-transfer printed on SiO2 into Complementary Metal-Oxide-Semiconductor backend for Si photonics application on 8″ wafer platform

Micro-Transfer printing (µTP) is a promising technique for hetero-integration of III-V materials into Si-based photonic platforms. To enhance the print yield by increasing the adhesion between the III-V material and Si or SiO2 surface, an adhesion promoter like Benzocyclobutene is typically used as interlayer. In this work, we demonstrate µTP of InP based coupons on SiO2 interlayer without any adhesive interlayer and investigate the mechanism of adhesive free bonding. Source coupons are InP-based coupon stacks on a sacrificial layer that is removed by a chemical wet etch with FeCl3. For the target we fabricated amorphous-Si waveguides on 8″ wafer encapsulated by a High Density Plasma SiO2 which was planarized by a chemical mechanical polishing procedure. We used O2 plasma to activate both source and target to increase adhesion between coupon and substrate. To get a better understanding of the bonding mechanism we applied several surface characterization methods. Root mean square roughness of InP and SiO2 was measured by atomic force microscopy before and after plasma activation. The step height of the micro-transfer printed source coupon on the target wafer is estimated by optical step profiler. We used Raman peak position mappings of InP to analyze possible strain and contact angle measurements on SiO2, before and after plasma activation to observe a change in the hydrophilicity of the surface. X-ray Photoelectron Spectroscopy analysis was used to characterize the surface energy states of P2p, In3d, O1s for InP source and Si2p, O1s for SiO2 target. Our results demonstrate direct bonding of InP coupons by means of µTP without the need of a strain-compensation layer. In this way, a promising route towards Complementary Metal-Oxide-Semiconductor compatible use of µTP for the hetero-integration of InP is provided.

Neogene erosion surfaces and the Andean uplift in northern Peru

The Andean flank in central Peru is characterized by stepped profiles involving up to 20 surfaces and pediments resulting from multiple episodes of uplift and erosion. The study area exhibits the same sequence of surfaces and pediments. The erosional features are also recognized in the Eastern Cordillera in northern Peru. This paper focuses on the seven highest features in the range c. 2800–4700 m. Remnants of the four surfaces higher than 3800 m, which were formed during the interval c. 18–12 Ma, are only found south of latitude 6–6.5° S. The Miocene metallogenic belt associated with the Western Cordillera terminates abruptly at that same latitude. The area north of c. 6° S does not have any features higher than c. 3500 m, which is interpreted as indicating a later initiation of uplift. It also lacks any sign of magmatic activity. On the basis of these factors, the Central Andes are considered to terminate at c. 6° S, the ranges to the north being assigned to the Northern Andes. Once episodic uplift was initiated in the area north of 6° S, it continued at the same rhythm as in the region to the south. There was no apparent change in the pattern of episodic uplift when the normal subduction regime changed to a flat-slab regime at c. 11 Ma, probably as a result of the subduction of the Inca Plateau. The distribution of the erosion surfaces indicates that episodic uplift affected the whole of the Andean Block in northern Peru. It appears that the individual episodes occurred simultaneously and produced the same amount of uplift over the whole width of the cordilleras. There is no sign of any interruption in the process, implying a continuous orogeny from the Mid-Miocene onwards.

Performance analysis of dual material control gate cavity on source electrically doped TFET biosensor for biomedical applications

The fabrication complexity, low sensitivity, detection speed, and costs associated with nanoscale devices have been significant concerns in the development of label-free biosensors. To address these issues, we report a novel dual material control gate cavity on source electrically doped tunnel field-effect transistor (DM-CG-CS-ED-TFET) for label-free biosensors. In this regard, the n+ drain and p+ source regions within the proposed device are induced by applying polarity gate (PG) bias voltages of PG-1 = +1.2 V and PG-2 = −1.2 V, respectively, across the respective polarity gate electrodes. This approach not only overcomes doping control issues but also avoids thermal budget constraints and minimizes fabrication complexity when compared to conventional TFET. For biomolecule sensing in the device, a nanogap cavity is created within the gate dielectric by selectively etching a portion of the polarity gate dielectric layer towards the source side. The performance of the proposed biosensor device is evaluated based on the variations in carrier concentration profile, energy band diagram, electric field, transfer (IDS - VGS) characteristics, drain current (IDS) sensitivity, ON-state current (ION) sensitivity, switching ratio (ION/IOFF) and subthreshold swing (SS) sensitivity. The sensitivity of the device is also investigated based on nano-cavity dimensions, practical challenges such as various filling factors, and the step profile generated from the steric hindrance. Moreover, the effect of temperature on sensitivity has also been investigated. For this, various biomolecules including Streptavidin (k = 2.1), APTES (k = 3.57), ferrocytochrome c (k = 4.7), keratin (k = 8) and Gelatin (k = 12), have been investigated for their performance using Silvaco ATLAS device simulator. The simulation results demonstrate that the proposed biosensor is a viable option for biosensing applications in biomedical engineering.

The preparation and wettability of the Sn-9Zn-2.5Bi-1.5In solder paste for SMT process and high shear ball performance

Purpose This study aims to focus on the surface mount technology (SMT) mass production process of Sn-9Zn-2.5Bi-1.5In solder. It explores it with some components that will provide theoretical support for the industrial SMT application of Sn-Zn solder. Design/methodology/approach This study evaluates the properties of solder pastes and selects a more appropriate reflow parameter by comparing the microstructure of solder joints with different reflow soldering profile parameters. The aim is to provide an economical and reliable process for SMT production in the industry. Findings Solder paste wettability and solder ball testing in a nitrogen environment with an oxygen content of 3,000 ppm meet the requirements of industrial production. The printing performance of the solder paste is good and can achieve a printing rate of 100–160 mm/s. When soldering with a traditional stepped reflow soldering profile, air bubbles are generated on the surface of the solder joint, and there are many voids and defects in the solder joint. A linear reflow soldering profile reduces the residence time below the melting point of the solder paste (approximately 110 s). This reduces the time the zinc is oxidized, reducing solder joint defects. The joint strength of tin-zinc joints soldered with the optimized reflow parameters is close to that of Sn-58Bi and SAC305, with high joint strength. Originality/value This study attempts to industrialize the application of Sn-Zn solder and solves the problem that Sn-Zn solder paste is prone to be oxidized in the application and obtains the SMT process parameters suitable for Sn-9Zn-2.5Bi-1.5In solder.