Rc Values Research Articles

Study of the compression properties of welded seams formed using hot wedge, hot air, ultrasonic, and high-frequency welding techniques

The compression properties of welded seams depending on welding parameters using the hot wedge and hot air welding technique, ultrasonic welding technique, and high-frequency welding technique were studied. The compression properties, expressed by parameters such as compressional energy WC, compressional resilience RC, linearity LC, and compressibility C, are important information about the welded seam quality in terms of touch, voluminosity, stiffness, and flexibility of the welded seam. KES-FB and FAST measurement systems were used to test the compression properties of the welded seams. Based on the analysis of the results obtained, the influence of the welding parameters on the compression properties of the welded seam was determined. The results of the investigation showed that improperly selected welding parameters, such as the supply or introduction of too much heat into the material to be welded or too long exposure of the material in the weld zone to heat, result in welded seams with expressive extrusion edges, which affects the quality of the welded seams. These welded seams have very low values of compressional resilience RC and very high values of compressional energy WC and compressibility C.

Morphometric characteristics of the Alas-Singkil drainage basins

The Alas-Singkil drainage basin is the broadest watershed and an essential ecosystem for maintaining hydrology and ecosystems in the northern Sumatera. This study aims to describe the morphometric and hydrological characteristics of the Singkil watershed. The data sourced from Google Earth, DEM data and the results of team expeditions at the sub-watershed locations. The data analysis is related to the characteristics of the Singkil watershed, which include watershed area, watershed shape, river network, river flow pattern, river flow density, and watershed hydrology. Analysis of hydrological characteristics by calculating the peak of the flood was also carried out. The results showed that the Singkil watershed is a broad watershed with an area of 12027.18 km2. The Alas-Singkil drainage basin consists of 7 sub-watersheds, with the length of the main river reaching 368 km. The order of Singkil watershed reaches 8 orders and consists of 7235 orders 1, 1964 orders 2, 390 orders 3, 92 orders 4, 26 orders 5, 6 orders 6, 4 orders 7. The shape of Alas-Singkil drainage basin is elongated with RC value of 0.16. The level of river branching in the Alas-Singkil watershed is 4.76. The maximum discharge in the Alas-Singkil watershed reaches 59,178 m3/sec.

ZrO2-anchored rGO nanohybrid for simultaneously enhancing the wear resistance and anticorrosion performance of multifunctional epoxy coatings

ZrO2 nanoparticles were controllably anchored on the surface of rGO nanosheets via an environmentally friendly single-step hydrothermal reaction and then incorporated into epoxy coatings to simultaneously improve the wear resistance and anticorrosion performance of the coatings. Based on the structural characterization and analysis, ZrO2 nanoparticles were homogeneously anchored on the surface of rGO through the charge attraction between GO and the Zr(IV) complex ions in the precursor. The addition of 0.5 wt% ZrO2@rGO nanohybrids to the epoxy resin coating (ZrO2@rGO/EP) significantly improved the adhesion strength, impact resistance and surface hardness. Tribological investigation revealed that the average friction coefficient of ZrO2@rGO/EP decreased by 41.96% and the wear resistance improved by 57.69%. Characterization of the worn surface indicated that the main wear mechanism of ZrO2@rGO/EP was abrasive wear with smooth and slightly damaged surface morphology. The anti-wear improvement is attributed to the filling effect of small wear debris of ZrO2@rGO/EP on the groove and the loading effect of hard ZrO2@rGO nanohybrid debris. SEM images and EDS line scan of worn surfaces of the friction counterparts confirmed the friction transfer effect of ZrO2@rGO/EP. After the ZrO2@GO/EP was soaked in 3.5 wt% NaCl solution for 7 days, the impedance modulus reached 2.50 × 106 Ωcm2, one order of magnitude higher than that of pure EP. The phase angle (105 Hz) was close to 90°, almost twice that of pure EP. The Rc value fitted via Zview software was two orders of magnitude higher. Electrical equivalent circuit models indicated the enhanced anti-corrosion performance. The as-prepared ZrO2@rGO hybrid in EP coatings could effectively prevent electrolyte penetration, and ZrO2 nanoparticles played a synergistic role with rGO nanosheets in alleviating corrosion. It provides a controllable and effective strategy for developing multifunctional ceramic/graphene/organic coatings with enhanced wear resistance and anti-corrosion performance.

Soil Property and Subsurface Heterogeneity Control on Groundwater Recharge of Vadose Zone Injection Wells

Vadose zone well (VZW) injection is an effective method of managed aquifer recharge (MAR), and it plays an important role in semiarid and arid regions. Accurate estimation of the recharge of VZW injection remains a challenge in the field of hydrology due to the nonlinear nature of the process in the vadose zone. To improve knowledge of VZW injection, a finite-element numerical model was developed by COMSOL Multiphysics to evaluate the soil property and subsurface heterogeneity control on the recharge of VZWs. Several numerical experiments were conducted to estimate the characteristic arrival time and cumulative recharge volume of injected water for different subsurface conditions. Simulation results indicate that soil properties have a profound influence on the recharge of VZWs and saturated hydraulic conductivity plays a more important role than the Van Genuchten –Mualem soil constitutive model parameters α and n in the influences on the recharge. Subsurface heterogeneity has large impacts on the recharge of VZWs as well. The presence of a low permeable layer in the aquifer hinders the infiltration of injected water and reduces recharge rate Qwt and cumulative recharge volume Vwt. These influences are affected by depth Dc, lateral extension Rc, thickness Bc, and hydraulic conductivity Ks of the low permeable layer. Whether the well screen cuts through the low permeable layer is a factor that influences the effects of these parameters in two forms. When the well screen cuts through the low permeable layer, Qwt and Vwt decrease substantially as Dc increases, and the change of Bc has a greater impact on recharge than Ks; when the low permeable layer is below the well screen, the change of Dc only has slight influence on recharge, and the cases with the same hydraulic conductance value of Ks/Bc have similar Qwt and Vwt. For the low permeable lens, when the well screen cuts through it, the increase of Rc leads to slight decrease of Qwt and Vwt, which are more obvious in the later stage of VZW injection. When the low permeable lens is below the well screen, the increase of Rc makes Qwt decrease in the early stage of VZW injection, and then Qwt for different values of Rc reach similar asymptotic values in the later stage. Understanding the influences of soil properties and subsurface heterogeneity on the recharge of VZWs provides physically based guidance for the design and management of VZWs.

Effect of Cu substitution on the type of magnetic phase transition and magnetocaloric effect in the ErCo2-xCux compounds

In this paper, the crystal structure, magnetic phase transition and magnetocaloric properties of the ErCo2-xCux (x = 0.12, 0.24, 0.36 and 0.48) compounds have been investigated in detail. All of the compounds crystallize in the C15 cubic Laves structure (MgCu2-type) with the Fd-3 m space group. The substitution of Cu for Co is accompanied by an increase of the Curie temperature Tc from 31.5 K to 68 K for x varying from 0.12 to 0.48. The nature of the magnetic phase transition, determined by the results of the Arrott plots and Landau theory, changed from a first order to a second order in the ErCo2-xCux compounds with the Cu content increasing. The isothermal entropy change -∆SM is calculated according to isothermal magnetization measurements using Maxwell’s relation. For an applied magnetic field change of 0–5 T, the -∆SM decreased from 30 J kg−1 K−1 for x = 0.12 to 10.9 J kg−1 K−1 for x = 0.48, whereas the working temperature range became wider due to that the magnetic transition type changed from a first order to a second order, which is a benefit for the application of the magnetic refrigeration. The corresponding refrigerant capacity RC values are 270.8 J kg−1, 194.1 J kg−1, 261.8 J kg−1 and 264.8 J kg−1, respectively.

Effect of Compaction Ratio on Mechanical Properties of Low-Strength Hydraulically Bound Mixtures for Road Engineering.

Road layers should be properly compacted to obtain an adequate bearing capacity and durability. Both the unbound and hydraulically bound mixtures used in the layers require compaction. After compaction and hardening, soil mixed with a binder acquires mechanical features that unbound soil lacks, including tensile strength (Rit) and unconfined compressive strength (Rc). The effect of the compaction ratio (DPr) of the low-strength cement-stabilised soils on these features has rarely been investigated. This study investigates the influence of the compaction ratio on the mechanical properties of hardened, stabilised mixtures of medium-grained sand with 5%, 6.5%, and 8% Portland cement. Cement–soil stabilisation tests showed that compressive strength depends exponentially on the compaction ratio, whereas tensile strength and the stiffness modulus depend linearly on the compaction ratio. For tensile strength and the dynamic stiffness modulus, the effect is not statistically significant, and the usual practice of ignoring compaction dependence is justified. For compressive strength, however, the effect is significant, especially when DPr = 98–100%. When the values of Rc and Rit strengths at various DPr were normalised by those at 100%, it was found that mixtures with higher strengths are the least resistant to changes in the compaction ratio. Knowing the percentage by which the value of a given parameter changes with compaction can be extremely valuable in engineering practice.

Synthesis, Characterization, and DFT studies of Praseodymium (III) Octanoyl‐DL‐aminocarboxylate Complexes

AbstractRare‐earth amino acid complexes have attracted much attention for their unique properties and potential applications in various fields. In this study, we synthesized and characterized the praseodymium(III) complexes with octanoyl‐DL‐alaninates (Pr(oct‐ala)3), octanoyl‐DL‐phenylalaninate (Pr(oct‐phe)3), and octanoyl‐DL‐serinates (Pr(oct‐ser)3) ligands. Elemental analysis, NMR, and FT‐IR spectra confirmed the elemental content, and functional groups information in the synthesized complexes. The XRD profile demonstrated the amorphous structure of praseodymium(III) complexes. Polarized optical microscopy gave insight into the liquid crystal properties of the praseodymium(III) complexes. UV‐Vis and PL emission spectra illustrated the excellent optical absorption properties and emitted white light. DFT calculation confirming the chelating bidentate mode of praseodymium(III) complexes. The atoms in molecules theory calculated the topological properties of praseodymium(III) complexes. The ▿2ρ and ρc values are in the range of 0.1966–0.2019 a.u and 0.0583–0.0608 a.u, respectively, illustrating closed‐shell interactions between ligands and Pr3+.

Negative Differential Resistance Behavior in n‐Channel Organic Thin‐Film Transistors Based on C60and PTCDI‐C8: Electrical Characterization and Parameter Extraction

Organic thin‐film transistors (OTFTs), based on two n‐type structures of fullerene (C60) andN,N′‐dioctyl‐3,4,9,10‐perylenedicarboximide (PTCDI‐C8), are investigated. The two OTFT devices reveal a negative differential resistance (NDR) behavior in the saturation region of the output curves. The OTFT based on C60shows a more pronounced NDR than that based on PTCDI‐C8. The main origin of the NDR is ascribed to the trapping states. In addition, the contact resistance (Rc) of the two devices, extracted using the developed voltage transition method (Vtrmethod), as well as the obtained values ofRc, are in fair agreement with the experimental values extracted using the total resistance. The device based on C60exhibits a higherRcthan that based on PTCDI‐C8. OTFT parameters, such as transconductance (gm), mobility (μmax), threshold voltage (Vth,), turn‐on voltage (Von), ratio currentIon/Ioff, and subthreshold slope (SS), are obtained in the linear and saturation regimes. The extracted value of SS for the OTFT based on C60is very small compared with that of the device based on PTCDI‐C8, which indicates an increase in the density of trapping states in the C60film.

Novel Foaming-Agent Free Insulating Geopolymer Based on Industrial Fly Ash and Rice Husk.

This study highlights the synthesis of a new thermal insulating geopolymer based on the alkaline activation of fly ashes. A porous geopolymer material can be prepared without the addition of a foaming agent, using high ratio solution/ashes (activating solutions used are water, sodium or potassium hydroxide). In order to increase the porosity of the material and to make it more ecological, rice husks are incorporated into the formulation. The geopolymer materials were prepared at room temperature and dried at moderate temperature (105 °C) by a simple procedure. The microstructural characteristics of these new porous geopolymers were assessed by optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Infrared spectroscopy (FTIR) was used to confirm the geopolymerisation. The effect of the ratio solution/ashes and the percentage of the rice husk addition on thermal and mechanical analysis was evaluated. An insulating material for a solution/ashes ratio of 0.9 and a rice husk content of 15% having a λ value of 0.087 W/(m·K), a porosity of 61.4% and an Rc value of 0.1 MPa was successfully prepared.

Attractive properties of magnetocaloric spark plasma sintered LaFe11.6Si1.4/Pr2Co7 composites for near room temperature cooling applications

A series of LaFe11.6Si1.4/xwt%Pr2Co7 (x = 0, 5, 10) composites, with a range of particle size of LaFe11.6Si1.4 powders, were successfully fabricated by spark plasma sintering (SPS), followed by annealing. The influence of the particle size of the LaFe11.6Si1.4 powders and the Pr2Co7 binder content on the phase constitution, microstructure, thermal, mechanical, magnetic and magnetocaloric properties were studied. The Pr2Co7 binder content (10 wt%) and the particle size of LaFe11.6Si1.4 powders (100–200 µm) were chosen to be conducive to the formation of the desired 1:13 phase. The magnetic and magnetocaloric properties were influenced by the synergistic effects of Pr and Co atomic diffusion as well by the particle size of the LaFe11.6Si1.4 majority phase powders. The values of TC, (ΔSM)max and RC for the sample could be tuned in the range of 230–297 K, 1.90–3.70 J/kg·K and 84–149 J/kg (ΔH=2 T), respectively, by tuning the Pr2Co7 content and the particle size of the LaFe11.6Si1.4 powders. Significantly, this TC range covers a wide variety of near room temperature cooling applications. The excellent values of thermal conductivity, maximum compressive strength and strain were in the range of 14–20.90 W/m·K, 930–1405 MPa and 5.9–7.9%, respectively. These features make these materials very promising candidates for near room temperature magnetic cooling applications.

Modeling the recent outbreak of COVID-19 in India and its control strategies

The recent emergence of COVID-19 has drawn attention to the various methods of disease control. Since no proper treatment is available till date and the vaccination is restricted to certain age groups, also vaccine efficacy is still under progress, the emphasis has been given to the method of isolation and quarantine. This control is induced by tracing the contacts of the infectious individuals, putting them to the quarantine class and based on their symptoms, classifying them either as the susceptible or sick individuals and moving the sick individuals to the isolated class. To track the current pandemic situation of COVID-19 in India, we consider an extended Susceptible-Exposed-Quarantine-Infected-Isolated-Recovered (SEQ1IQ2R) compartmental model along with calculating its control reproductive number Rc. The disease can be kept in control if the value of Rc remains below one. This “threshold” value of Rc is used to optimize the period of quarantine, and isolation and have been calculated in order to eradicate the disease. The sensitivity analysis of Rc with respect to the quarantine and isolation period has also been done. Partial rank correlation coefficient method is applied to identify the most significant parameters involved in Rc. Based on the observed data, 7-days moving average curves are plotted for prelockdown, lockdown and unlock 1 phases. Following the trend of the curves for the infection, a generalized exponential function is used to estimate the data, and corresponding 95% confidence intervals are simulated to estimate the parameters. The effect of control measures such as quarantine and isolation are discussed. Following various mathematical and statistical tools, we systematically explore the impact of lockdown strategy in order to control the recent outbreak of COVID-19 transmission in India.

The state of the respiratory system of students in conditions of high-altitude hypoxia

The article presents the results of studies on the influence of mountain hypoxia on the state of the students’ respiratory system. When exposed to oxygen deficiency, only the respiratory capacity of the lungs undergoes significant changes. For instance, the RC level in female students under the influence of hypoxia gradually increased in conditions of medium altitude, reaching the maximum value of 0.64 liters (P ˂ 0.05), and on the plain - 0.44 liters. The RC value in young men reached the highest value of 0.74 liters in mid-altitude conditions, and on the plains, it constitutes 0.56 liters. The highest respiration rate for young men of 18.2 movements per minute was noted at an altitude of 600 meters, and the lowest - 17.4 at an altitude of 170 m. The maximum level of respiratory capacity while inhaling in girls is 1.24 liters, detected at an altitude of 600 meters, and the minimum level of 1.18 liters is noted at 170 m. The value of respiratory capacity while exhaling among young men living in the Sharoi region increased to 2.32 liters, and for those from Grozny - 2.24 liters. The highest VC level in girls - 3.87 liters - was found in the middle mountains, and on the plains, it was 3.58 liters. The VC value in young men, gradually increasing, reaches the highest value under the conditions of the Sharoi region - 4.57 liters, and in Grozny it was 4.28.

Investigation on the Effects of Interconnect RC in 3nm Technology Node Using Path-Finding Process Design Kit

With the continuous development of front-end-of-line (FEOL) technology, the development of interconnection processes at nanoscale process nodes is becoming important. We conducted a post-layout circuit simulation to consider the effect of parasitic R and C components of middle-of-Line (MOL) and back-end-of-line (BEOL) on the circuit performance. We constructed a process design kit (PDK) for path-finding to analyze the circuit layout in a 3nm technology node based on gate-all-around FET (GAA-FET). It consists of the spice model library that satisfies the 3nm power performance area (PPA) target, and the layout versus schematic (LVS), parasitic extraction (PEX) model that checks whether the layout and schematic match, extracts the RC values in the FEOL MOL and BEOL areas. Subsequently, the effect of the interconnection on complex logic circuits (RO, full adder) was confirmed using PDK. As a result of quantifying the effects of FEOL, MOL, and BEOL on the circuit, circuit degradation due to the RC of MOL and BEOL accounts for more than 60%. Furthermore, we introduced the air spacer process as a way to improve the circuit performance by reducing the CMOL owing to the reduction in the dielectric constant of the spacer. When an air spacer is introduced, based on 9-stages FO1 INV RO with k = 7 at V_DD = 0.7V, under iso-speed condition, the active power decreases by 30%, 35% when k is 3.3, 1.65, respectively. Under iso-power condition, frequency increases by 9%, 11% when k is 3.3, 1.65, respectively. And based on full adder with k = 7 at V_DD = 0.7V, Under iso-speed conditions, the active power decreases by 47%, 58% when k is 3.3, 1.65, respectively. Under iso-power conditions, the delay decreases by 14%, 20% when k is 3.3, 1.65, respectively. PDP decreases by 22%, 32% when k is 3.3, 1.65, respectively. EDP decreases by 31%, 44% when k is 3.3, 1.65, respectively. In conclusion, in this work, we provide a guide for determining the BEOL load and developing an improved wiring process.

Financing constraints change of China's green industries

<abstract> <p>Adequate funding is a crucial factor for the sustainable development of green industries. However, most green firms have suffered from financing constraints due to the negative externalities and information asymmetry of green finance. This study analyzes the driving factors of financing constraints index (FCI) of green industries from 2010 to 2019 using shift-share analysis. At the regional level, this study decomposes the change in FCI into three factors: national FCI change effect (NC), regional FCI change effect (RC), and regional FCI structure effect (RS). At the industry level, the study decomposes the change in FCI of green sub-industries into three factors: total industries FCI change effect (TIC), green industries FCI structure effect (GIS), and green sub-industries FCI structure effect (GSIS). The results show that the financing constraints on Chinese listed companies are getting stronger with each passing year. In particular, the financing constraints on green industries start to become larger than those of non-green industries after 2015. The decomposition results show that NC for each province is positive and relatively similar from 2010 to 2019. Nearly half of the provinces have positive RC values and there are more provinces with positive RS effects than those with negative RS effects. Most provinces are dominated by NC and RS effects. From the three green sub-industries, we observe that the TIC of all three sub-industries is positive, and GIS is positive in most years, while GSIS presents different characteristics. This study provides policy implications for alleviating financing constraints in green industries.</p> </abstract>

Nondestructive detection of total soluble solids in grapes using VMD-RC and hyperspectral imaging.

Total soluble solids (TSS) are one of the most essential attributes determining the quality and price of fruit. This study aimed to use hyperspectral imaging (HSI) and wavelength selection for nondestructive detection of TSS in grape. A novel method involving variational mode decomposition and regression coefficients (VMD-RC) was proposed to select feature wavelengths. VMD was introduced to decompose the hyperspectral images data of samples with bands of (400.68-1001.61nm) to get a series of feature components. Afterward, these components were processed separately using regression analysis to obtain the stability values of RC of each component. Finally, a filter-based selection strategy was used to screen key wavelengths. The least squares support vector machine (LSSVM) and partial least squares (PLS) were constructed under full and feature wavelengths for predicting TSS. The VMD-RC-LSSVM model obtained the best prediction accuracy for TSS, with of 0.93, with of 0.6 %, with of 18.14 and of 3.69. The overall results indicated that the VMD-RC algorithm can be used as an alternative to handle high-dimensional hyperspectral images data, and HSI has great potential for nondestructive and rapid evaluation of quality attributes in fruit. PRACTICAL APPLICATION: Traditional methods of evaluating grape quality attributes are destructive, time-consuming and laborious. Therefore, HSI was used to achieve rapid and nondestructive determination of TSS in grape. The results indicated that it was feasible to use HSI and variable selection for predicting TSS. It is of great significance to improve grape quality, guide postharvest handling and provide a valuable reference for noninvasively evaluating other internal attributes of fruit.

Study and Analysis of Simple and Precise of Contact Resistance Single-Transistor Extracting Method for Accurate Analytical Modeling of OTFTs Current-Voltage Characteristics: Application to Different Organic Semiconductors

Contact resistance (Rc) characterizes the interface of source-drain electrodes/organic semiconductors and controls the injection efficiency of carriers in organic thin-film transistors (OTFTs). This research paper presents and assesses two methods for extracting the value of the contact resistance from the measured current-voltage characteristics of OTFTs made with various p-type organic semiconductors as active layers. These two methods are the transition voltage method (TVM) and the transfer line method (TLM). The obtained Rc values by the TVM method are in fair agreement with those obtained by TLM, with a maximum percentage of difference around 10%, demonstrating the accuracy of the used transition-voltage method. An analytical model was employed to calculate output characteristics in the linear regime of OTFTs made with various organic semiconductors using the contact resistance values obtained by the transition voltage method. The calculated results are in reasonably good agreement with the experimental ones of each fabricated device, which affirms the ability of the used model to characterize the charge transport correctly in these types of devices. It can be concluded that the used TVM method is not only an easy and practical method, but also a precise way for extracting Rc in OTFTs produced using different organic semiconductor materials.

Morphometrics Characterization of Thin-Tail Sheep in Lowland and Highland Areas

Breed characterization in the livestock is important for the breeding program in the future. This research aimed to characterize Thin-tail sheep in the highland and lowland areas of Jambi Province based on 7 body measurements and body indices using multivariate analysis. Data were collected from 160 sheep consisted of 80 rams and 80 ewes from each area (320 sheep in total with 1-2 years old). The research showed that the principal component analysis (PCA) in this study was explained 65.84%-72.30% by body measurements and 78.23%-84.99% by body indices of the total phenotypic variance of animals. The body measurement of cannon circumference (CC) and body indices of area index (AI), relative cannon index (RCI), dactyl thorax index (DTI), conformation index (CI), and index of body weight (IBW) were selected as the discriminating variable for Thin-tail sheep in different areas. However, this study’s canonical correlation (rc) values were 0.44 for body measurements and 0.47 for body indices. Therefore, about 67.5% of Thin-tail sheep from the lowland area and 57.5% of Thin-tail sheep from the highland area can be characterized with body measurements. Hence, about 61.2% of Thin-tail sheep from the lowland area and 65.6% of Thin-tail sheep from the highland area can be characterized with body indices. Temperature, humidity, rainfall, and length of radiation in the highland areas are lower than in the lowland areas. The cluster analysis in four Thin-tail sheep populations revealed two clusters, i.e., cluster 1 consisted of Kerinci and Sungai Penuh and cluster 2 consisted of Muaro Jambi and Batanghari. It was concluded that about 60% of Thin-tail sheep could be characterized through their body indices.

Solution combustion synthesis of rGO-Fe2O3 hybrid nanofiller for linseed oil based eco-friendly anticorrosion coating

The synthesis of graphene based composite materials by simple environment friendly method is of prime importance. So, we report the synthesis of reduced graphene oxide-iron oxide (rGO-Fe2O3) nanocomposite by the solution combustion method. The rGO-Fe2O3 is employed as a nanofiller material in epoxidized linseed oil (ELO) based anti-corrosion coating. To ensure environmental sustainability, the curing agent for ELO resin is also prepared by using linseed oil. The synthesized rGO-Fe2O3, resins, and curing agent were well characterized by X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) and Proton nuclear magnetic resonance (1H NMR) techniques. The mild steel coupons coated with the nanocomposite were analyzed for their stability and anti-corrosion behavior using scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle, and electrochemical studies. Electrochemical impedance data showed that the ELO-rGO-Fe2O3 coating showed a very large Rc value (8.874 ×107 Ω cm2) and significantly low capacitance (3.63 ×10−10 F cm2) when compared to ELO coating, indicating its excellent corrosion resistivity. Further, corrosion protection ability was observed up to 44 days in 3.5 wt% NaCl solution. The results indicate that the rGO-Fe2O3-ELO composite coating acts as a durable and sustainable substitute for petroleum-based coating and can find potential applications in coating industries.

Spatial Distribution, Risk, and Influencing Factors of River Water-Sediment Heavy Metals in the Lower Reaches of the Qianhe River

The spatial distribution of heavy metals in rivers is affected by human activities and the natural environment, posing a risk to human health related to heavy metal pollution. In order to study the characteristics, health risk levels, and influencing factors of heavy metal distribution and pollution in the lower reaches of the Qianhe River, 19 surface sediments and 20 water samples were collected, and the contents of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were measured by inductively coupled plasma mass spectrometry(ICP-MS). Using the DEM, air temperature, precipitation and other 11 factors as independent variables, the spatial differentiation of heavy metal pollution in sediments were explored based on geo-detector and geo-weighted regression model. The results showed that the eight heavy metal contents in the lower reaches of the Qianhe River did not exceed the "Surface Water Environmental Quality Standards" Ⅱ for water-like bodies, in which the variation coefficient of Pb element was 3.11, and the high content areas were mainly concentrated around Dongling Smelting Company and Fengxiang Railway Station. The average Rc value of adult carcinogens in water bodies was 7.72 E-06, showing a low risk level, and the children's carcinogens average Rc value was 1.17 E-04, showing a strong risk degree. The non-carcinogen risks for adults and children were both tolerable. The total high R value for children was mainly concentrated around Fengxiang Railway Station, posing a high risk. Sedimentation of heavy metals, except As and Mn, exceeded the soil background value in Shaanxi Province. The average content of Cd element was 1.12 mg·kg-1, which was 12 times the soil background value in Shaanxi Province. The pollution of Cd, Zn, and Pb was high, and distributed mainly in Changqing Village, Nanwan Village and Niujiatan Village, Gaozhuang, and Dongling Smelting Company. PLIzone of heavy metals in the sediments in the study area was 1.71, which was light pollution. DEM, temperature and precipitation were the main natural factors influencing the spatial pattern of heavy metal pollution load index(PLI) in sediments, and their nonlinear interactions were enhanced, which may play a role in the spread of heavy metals in sediments. This research can provide a scientific basis for urban planning and human health risks prevention in the Qianhe River.

Optimization of annealing conditions for Ag/p-GaN ohmic contacts.

The electrical and optical properties of Ag/p–GaN contacts have been investigated as a function of the annealing temperature, oxygen concentration, and annealing time. Specific contact resistance (ρc) values as low as 1.2 × 10–4 Ω·cm2 were obtained from the Ag/p–GaN contact annealed at 400 °C for 60 s in ambient O2/N2 (1:10). We found that the participation of oxygen improves the formation of ohmic contacts. Oxygen might remove the H in Mg–H complexes to activate the Mg acceptors and enhance Ga out-diffusion to form an Ag–Ga solid solution. We also found that the reflectivity of the Ag layer decreases with increasing annealing temperature in the O2-containing ambient environment. Thus, an optimal annealing condition of Ag/p–GaN for blue and green LEDs is suggested based on these results. We also used the suggested annealing conditions to form ohmic contacts on DUV LEDs and achieved good electrical performance. The forward voltages of UVC LEDs fabricated with annealed Ag contacts were 6.60 V (7.66 V) at a 40 mA (100 mA) injection current.