Metal Work Research Articles

Combination of enrichment factor and positive matrix factorization in the estimation of potentially toxic element source distribution in agricultural soil.

The study intended to assess the level of pollution of potential toxic elements (PTEs) at different soil depths and to evaluate the source contribution in agricultural soil. One hundred and two soil samples were collected for both topsoil (51), and the subsoil (51) and the content of PTEs (Cr, Cu, Cd, Mn, Ni, Pb, As and Zn) were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The concentrations of Zn and Cd in both soil horizons indicated that the current study levels were higher than the upper continental crust (UCC), world average value (WAV), and European average values (EAV). Nonetheless, the concentration values of PTEs such as Mn and Cu for EAV, As, Cu, Mn, and Pb for UCC, and Pb for WAV were lower than the average values of the corresponding PTEs in this study. The single pollution index, enrichment factor, and ecological risk revealed that the pollution level ranged from low to high. The pollution load index, Nemerow pollution index, and risk index all revealed that pollution levels ranged from low to high. The spatial distribution confirmed that pollution levels varied between the horizons; that is, the subsoil was considered slightly more enriched than the topsoil. Principal component analysis identified the PTE source as geogenic (i.e. for Mn, Cu, Ni, Cr) and anthropogenic (i.e. for Pb, Zn, Cd, and As). PTEs were attributed to various sources using enrichment factor-positive matrix factorization (EF-PMF) and positive matrix factorization (PMF), including geogenic (e.g. rock weathering), fertilizer application, steel industry, industrial sewage irrigation, agrochemicals, and metal works. Both receptor models allotted consistent sources for the PTEs. Multiple linear regression analysis was applied to the receptor models (EF-PMF and PMF), and their efficiency was tested and assessed using root-mean-square error (RMSE), mean absolute error (MAE), and R2 accuracy indicators. The validation and accuracy assessment of the receptor models revealed that the EF-PMF receptor model output significantly reduces errors compared with the parent model PMF. Based on the marginal error levels in RMSE and MAE, 7 of the 8 PTEs (As, Cd, Cr, Cu, Ni, Mn, Pb, and Zn) analysed performed better under the EF-PMF receptor model. The EF-PMF receptor model optimizes the efficiency level in source apportionment, reducing errors in determining the proportion contribution of PTEs in each factor. The purpose of building a model is to maximize efficiency while minimizing inaccuracy. The marginal error limitation encountered in the parent model PMF was circumvented by EF-PMF. As a result, EF-PMF is feasible and useful for apparently polluted environments, whether farmland, urban land, or peri-urban land.

The human long noncoding RNAs CoroMarker, MALAT1, CDR1as, and LINC00460 in whole blood of individuals after controlled short-term exposure with ultrafine metal fume particles at workplace conditions, and in human macrophages in vitro

BackgroundShort-term inhalation of occupationally relevant ultrafine zinc/copper (Zn/Cu) containing welding fumes has been shown to induce subclinical systemic inflammation, associated with an elevated risk for cardiovascular diseases. The involvement of noncoding RNAs (lncRNAs) in this setting is currently unknown. However, lncRNAs have been reported to fulfill essential roles in, e.g., cardiovascular diseases, inflammation, infectious diseases, and pollution-related lung disorders.MethodsIn this study, the specific lncRNAs levels of the 4 lncRNAs CoroMarker, MALAT1, CDR1as and LINC00460 were determined by RT-qPCR in THP-1 macrophages exposed to Zn/Cu metal fume suspensions for 1, 2, and 4 hours in vitro. Furthermore, 14 subjects were exposed to Zn/Cu containing welding fumes (at 2.5 mg/m3) for 6 hours. Before, 6, 10, and 29 hours after exposure start, whole blood cell lncRNAs levels were determined by RT-qPCR.ResultsIn THP-1 macrophages, we observed a 2.3-fold increase of CDR1as at 1 h (Wilcoxon p = 0.03), a non-significant increase of CoroMarker at 1 h, and an increase of LINC00460 at 2 h (p = 0.03) and at 4 h (p = 0.06). In whole blood cells, we determined a non-significant upregulation of CDR1as at 6 h (p = 0.2), a significant downregulation of CoroMarker at 6 h (p = 0.04), and a significant upregulation of LINC00460 levels at 10 h (p = 0.04) and 29 h (p = 0.04). MALAT-1 remained unchanged in both settings.ConclusionThe orientation of regulation of the lncRNAs is (except for CoroMarker) similar in the in vitro and in vivo experiments and in line with their described functions. Therefore, these results, e.g. the upregulation of the potential risk marker for cardiovascular diseases, CDR1as, contribute to understanding the underlying mechanisms of Zn/Cu-induced subclinical inflammation in metal workers.

Extraction and physicochemical characterization of cashew nut-shell liquid in metal forming

ABSTRACT: Effective lubrication during metal working is critical to mitigating undesirable tool wear and poor surface finish of formed components. This paper investigated the physicochemical characteristics of cashew nut-shell-liquid (CNSL) with a view of determining its suitability for the development of an eco-friendly lubricant used in metal forming. The cashew nut shell oil (CNSO) was extracted by soxhlet method and characterised to determine its physicochemical properties including density, free fatty acid (FFA), and viscosity. In addition, the saponification value, iodine value, pH, flash point and friction coefficient were determined using relevant analytical tools. The results showed that CNSL yield from soxhlet solvent extraction is 45.6%, which is adjudged to be relatively substantial with regard to other extraction processes. Furthermore, the CNSL exhibited critical lubrication characteristics in terms of density (0.94 g/cm3), moisture content (3.96%), acid value (11.32 mg.KOH/g), FFA (3.7%), ester value (127.92 mg.KOH/g), saponification value (139.24 mg.KOH/g), pH value (4.61), iodine value (40.21 gI2/100 g), viscosity at 100 oC (14.12 Pa.s), friction coefficient (0.001) and flash point of 286.63 oC. Given these outcomes in comparison with commercial Chevron soluble oil, it is concluded that CNSL is suitable for use as a viable metal forming lubrication fluid.

Low contact resistivity of metal/n-GaN by the reduction of gap states with an epitaxially grown GaOx insulating layer

We investigated the contact properties of metal/n-GaN and metal/GaOx/n-GaN in terms of Fermi level pinning (FLP) by metal-induced and disorder-induced gap states (MIGS and DIGS). The work function of ten different metals spanned a wide range from 4.2 to 5.7 eV. The measured Schottky barrier height vs metal work function in metal/n-GaN showed the linear relationship with the slope parameter of S = 0.26 ± 0.01 for the doped and the undoped GaN, indicating a strong FLP. The insertion of a GaOx layer increased S to 0.35 corresponding to the decrease of the gap state density by ∼1.1 × 1013 states/(cm2 eV). A contact resistivity of 1.3 × 10−5 Ω cm2 was obtained in Al/GaOx (2.3 nm)/n-GaN (doped with 2 × 1018 cm−3 of Si), which was smaller by nearly three orders than that without the GaOx layer. The insulating property and partially epitaxial structure of GaOx were considered to be responsible for the reduction of the MIGS and DIGS densities, respectively, thereby relaxing FLP and leading to low contact resistivity. Optimization of the GaOx growth parameters may further improve the contact property.

Simulation of Molybdenum Disulfide based MOSFET Device using COMSOL Multiphysics software

In this work, 2D physical modeling and simulation of Molybdenum disulfide based MOSFET device using COMSOL multiphysics software is carried out. The impact of dielectric materials such as SiO2 and Al2O3 on the performance of FET are investigated. Threshold voltage (VT), sub-threshold swing and on/off ratio are some of the electrical parameters studied in this work. The values of channel doping concentration, choice of metal work function and dielectric material, and the corresponding thickness of the gate material, are systematically varied to arrive at the device threshold voltage. FET device with 50nm thick Al2O3 gate insulator exhibits a threshold voltage of 1V and an on/off ratio of 107, whereas the device with SiO2 as the gate material with the same thickness exhibited higher threshold voltage of 2.8V and lower on/off ratio of 106. The polynomial first order technique in the MATLAB curve fitting tool is utilized to determine the relation between VT and gate oxide thickness.

중대재해처벌법에 대비한 건설현장의 스마트기술 활용방안에 대한 연구

This study proposed a plan to easily handle the work of safety management officer at construction sites by effectively performing safety management work at construction sites using smart technology in preparation for the Serious Accidents Punishment Act. As a result of analyzing the research trends of the Serious Accidents Punishment Act, it can be summarized into network analysis studies such as problems and improvement directions, countermeasures from subcontractors and small and medium-sized construction companies, site size, etc. The relationship between the detailed process of the construction site and smart technology, which is the core of this study, was found in the order of earthwork, steelwork, roof work, reinforced concrete work, window work, drainpipe metal work, civil work, and stone work. This means that when smart technology is applied, the response to serious accidents factors is relatively highly related, so it can be effectively managed. The definitive weight of smart technology for the detailed construction process was determined as the top items: earthworks, steelworks, roof works, 65%, reinforced concrete works 20%, window works 10%, drainpipe works 3%, and stone works 2%. Based on this, it can be prepared by applying the degree of input of smart technology to the detailed schedule of construction sites in order to increase the practical use of smart technology in preparation for the Severe Accidents Punishment Act.

Experimental assessment of thermal and rheological properties of coconut oil-silica as green additives in drilling performance based on minimum quantity of cutting fluids

Conventional metal working fluids are prepared from petroleum based mineral oils with toxic, carcinogenic, non-biodegradable and unsustainable additives, which can cause serious environmental contamination and health risks to operators. Formulations with non-toxic emulsifiers and natural additives such as vegetable oils are currently being considered for further development and use of non-toxic tribological products. This study is concerned with the thermal and flow properties of a cutting fluid (taladrine, T) mixed with a phase change material (PCM) coconut oil (CO) in a proportion of 1:9 (CO-0.1T) and hydrophilic silica in 0.01, 0.03 and 0.05 vol fractions. The thermal properties were evaluated by differential scanning calorimetry (DSC) and thermal conductivity measurements while the flow properties were assessed by viscosity temperature curves. The addition of solid particles has demonstrated an enhancement of the thermal conductivities with small differences in the latent heat. The microstructure of the suspensions was established from the DSC cooling dynamic thermogram and the rheological measurements. These results were confirmed by the images of optical polarized microscopy in which plate-like needles were observed. The suspension of 0.03 silica in CO-0.1T demonstrated an adequate gel strength and produced a reduction of 11 °C in drilling performance. A Minimum Quantity of Cutting Fluid (MQCF) of 2 g as an alternative for dry machining and flood cooling. It also prevented evaporative loss and removed metal chips, as a high viscosity complex fluid. In this work the use of phase change materials filled with solid particles as a way of sustainable eco-friendly toxic waste removal in drilling was justified.

Numerical modeling of ultra-thin CuSbS2 heterojunction solar cell with TiO2 electron transport and CuAlO2:Mg BSF layers

The ternary chalcostibite copper antimony sulfide (CuSbS2) system, with its very high optical absorption coefficient, low-cost, vacuum-free fabrication techniques, and earth-abundant elements, is a rising candidate as solar absorber material for ultrathin film solar cells. However, due to the Schottky barrier formed at the back-contact and high carrier recombination at the CuSbS2/CdS interface, the efficiency of conventional CuSbS2/CdS heterojunction solar cell is very poor. This article proposes titanium dioxide (TiO2) as an alternative to CdS layer for the CuSbS2-based thin film solar cells (TFSCs). Using TiO2, CuSbS2, and Mg-doped CuAlO2 (CuAlO2:Mg) as an electron transport layer (ETL), absorber layer, and back-surface field (BSF) layer, respectively, a novel (Al/ITO/n-TiO2/p-CuSbS2/p+-CuAlO2:Mg/Au)-based npp+ heterojunction solar cell has been designed and simulated by SCAPS-1D solar cell simulator. The effects of integrating the CuAlO2:Mg BSF layer on the PV responses of the CuSbS2-based heterojunction solar cell in terms of the built-in potential and the back-contact carrier recombination have been studied. In addition, an investigation on the influences of various device parameters viz. carrier concentration and thickness of each layer, back-contact metal work function, shunt and series resistance, and working temperature have been carried out systematically. The results are analyzed in correlation with the PV parameters of the device to optimize the efficiency of the proposed solar cell. The optimized CuSbS2-based solar cell shows good performance stability at high temperature, with a maximum efficiency of 23.05% (Voc = 969 mV, Jsc= 34.61 mA/cm2, FF = 68.71%).

Pneumokokkenvaccinatie en lassers: als de rook om je hoofd is verdwenen

Pneumococcal vaccination and welders: when the smoke dissipates… Although pneumococcal disease is a major cause of morbidity and mortality, it is a rare disease in the working population. Since several decades, exposure to metal fumes is known to increase the risk of lobar pneumonia among an important occupational group, namely welders and metal workers. The theory is that metal fume alters the bacterial properties and/or the worker’s ability to withstand infection. The exact mechanisms are, however, still unclear. Outbreaks of invasive pneumococcal disease (IPD) caused by the siderophilic, gram-positive bacterium Streptococcus pneumoniae have been quite rare. However, several outbreaks have been reported at Finnish, French, Northern Irish, Norwegian, Singaporean and Swedish shipyards since 2015. Shipyard workers might have a higher risk of developing IPD mainly due to specific environmental factors present at shipyards. Preventive measures may include pneumococcal vaccination, improved ventilation, occupational hygiene measures, reinforcement of the proper use of respiratory protective equipment and anti-smoking campaigns. Therefore, targeted pneumococcal vaccination is recommended and should be offered to welders and potentially others with relevant occupational exposure to metal fumes (inorganic dusts) after the for an employer obligated risk assessment. This has been discussed in for example Norway, Sweden and the United Kingdom, but there is a need for increased international awareness of the occupational risk of severe pneumococcal disease.

Role of metallic contacts and defects on performances of an antimonide based thermo-photovoltaic cell: A numerical analysis

The effect of metallic contacts as well as defects and carrier recombinations on performances of an antimonide based cell, dedicated for thermo-photovoltaic conversion, is analyzed numerically. The analysis is done at room temperature and under 1500 K black body radiations as a light source. The complete cell’s structure is made of a multi-junction GaSb(p) / GaAlAsSb(p/n) / InAsSb(n) / GaSb(n) system. Based on experimental works related to metallic contacts on GaSb, values between 4.1 eV and 4.77 eV are used for the metal work function at the GaSb(p) front side while for the GaSb(n) back side, values used are between 4.01 eV and 4.6 eV. Considering a defectless structure, the conversion efficiency increases with the metal work function at the front contact. It reaches a maximum of 17.8 % for a work function around 4.4 eV. Beyond 4.4 eV, the efficiency remains constant. When increasing the work function at the back contact, from 4.04 eV to 4.7 eV, the conversion efficiency decreases from 18 % to 2 % while the external quantum efficiency is not affected. These results highlight the strong influence of the metallic contact on performances of InAsSb cell. The influence of defects at the GaAlAsSb/InAsSb interface was examined. For donors-like defects with high capture cross sections and low energy levels, an accumulation regime appears in InAsSb. This affects the conversion efficiency and the external quantum efficiency. For acceptors-like defects, the InAsSb layer is depleted and the conversion efficiency is affected while the quantum efficiency remains invariable.

β-(AlxGa1−x)2O3/Ga2O3 heterostructure Schottky diodes for improved VBR2/RON

We propose and demonstrate the use of a β-(AlxGa1–x)2O3 capping layer to achieve increased breakdown voltage, VBR, and VBR2/RON figure of merit in β-Ga2O3 Schottky diodes, where RON is the on-state resistance. We demonstrate that the addition of a 30 nm-thick β-(Al0.22Ga0.78)2O3 cap to an n-type β-Ga2O3 layer grown by metal organic chemical vapor deposition increases the breakdown voltage from 246 to 387 V in diodes with Pt contacts and 3 × 1016 cm−3 n-type doping. The cap increases the surface Schottky barrier with Pt, resulting in reduced carrier injection under reverse bias. The results are in good agreement with simulations which show that the addition of the capping layer enables the peak electric field at breakdown to increase from 2.5 to 3.6 MV/cm. Simulations further show that RON penalty associated with the (AlxGa1–x)2O3 cap can be almost completely eliminated by grading the capping layer. Thus, by raising the barrier height beyond the limit imposed by the metal work function and Fermi level pinning, the proposed heterojunction helps to improve VBR by reducing the reverse leakage current in ultrawide bandgap semiconductor diodes where bipolar doping remains a challenge.

Reduced Schottky barrier height at metal/CVD-grown MoTe2 interface

We demonstrated that Schottky barrier height (SBH) at the metal/CVD-grown MoTe2 interface can be significantly reduced with tunnel contact by inserting a thin Al2O3 layer regardless of the metal work function. The existence of strong Fermi level pinning (FLP) at the metal/MoTe2 interface was verified, while depinning cannot be achieved with Al2O3 insertion. Thus, the fixed charges inside the Al2O3 were proposed to be responsible for the effective SBH reduction in virtue of the eliminated SBH reduction after the post-annealing treatment. This work provides a feasible way to solve the contact issue and favors for the fabrication of high performance MoTe2-based electronic devices.

Structure and interactions at the Mg(0001)/water interface: An ab initio study.

A molecular level understanding of metal/bulk water interface structure is key for a wide range of processes, including aqueous corrosion, which is our focus, but their buried nature makes experimental investigation difficult and we must mainly rely on simulations. We investigate the Mg(0001)/water interface using second generation Car-Parrinello molecular dynamics (MD) to gain structural information, combined with static density functional theory calculations to probe the atomic interactions and electronic structure (e.g., calculating the potential of zero charge). By performing detailed structural analyses of both metal-surface atoms and the near-surface water, we find that, among other insights: (i) water adsorption causes significant surface roughening (the planar distribution for top-layer Mg has two peaks separated by ≈0.6Å), (ii) strongly adsorbed water covers only ≈14 of available surface sites, and (iii) adsorbed water avoids clustering on the surface. Static calculations are used to gain a deeper understanding of the structuring observed in MD. For example, we use an energy decomposition analysis combined with calculated atomic charges to show that adsorbate clustering is unfavorable due to Coulombic repulsion between adsorption site surface atoms. Results are discussed in the context of previous simulations carried out on other metal/water interfaces. The largest differences for the Mg(0001)/water system appear to be the high degree of surface distortion and the minimal difference between the metal work function and metal/water potential of zero charge (at least compared to other interfaces with similar metal-water interaction strengths). The structural information, in this paper, is important for understanding aqueous Mg corrosion, as the Mg(0001)/water interface is the starting point for key reactions. Furthermore, our focus on understanding the driving forces behind this structuring leads to important insights for general metal/water interfaces.

Design and investigation of dielectric modulated triple metal gate-oxide-stack Z-shaped gate horizontal pocket TFET device as a label-free biosensor

In this article, a dielectric modulated triple metal gate-oxide-stack Z-shaped gate horizontal source pocket tunnel field-effect transistor (DM-TMGOS-ZHP-TFET) structure has been investigated for the application of label free-biosensor. This work explores the advantage of gate work function engineering along with the gate-oxide-stack approach for the ZHP-TFET for the first time. An asymmetric nano-cavity is created adjacent to the source-channel junction to immobilize the target biomolecules conjugation to the proposed device. The sensitivity of the device is thoroughly investigated in terms of average subthreshold swing (SS), threshold voltage (V th) and the switching ratio (I on/I off) of the proposed device with the variation of the dielectric constant value inside the nano-gap under the gate electrode. The device characteristics are investigated with different combinations of metal work functions to match the desired feature and sensitivity of the device. In addition, the sensitivity analysis of the proposed device is analyzed in the presence of both positive and negative charged biomolecules in the cavity region to study the charge effect on label-free detection of the device. A comparative study is conducted between a single metal gate (SMG) ZHP-DM-TFET biosensor with the DM-TMGOS-ZHP-TFET biosensor explores the advantage of gate-work function engineering with a gate-oxide-stack approach. Interestingly the DM-TMGOS-ZHP-TFET biosensor shows superior results with a high current ratio sensitivity of 103 which is ten times more than the SMG-ZHP-DM-TFET biosensor and this device also exhibits low subthreshold characteristics.

A theoretical exploration of lead-free double perovskite La2NiMnO6 based solar cell via SCAPS-1D

To efficiently transform light energy into electrical via developing smart and environmentally benign materials is one of the most investigated ways of producing renewable energy. Here, inorganic-lead free and non-toxic double perovskite La2NiMnO6 material is employed as an active layer along with fullerene as ETL and NiO as HTL to form heterostructure perovskite solar cell. To determine the highest power conversion efficiency for the current photovoltaic device, an extensive theoretical analysis is implemented using the SCAPS-1D simulation tool. The best performing devices showed power conversion efficiency of 24.46% with excellent solar cell characteristics, whereas the performance can be tuned via careful modulation of metal work function. The theoretical finding suggests that with a systematic investigation of these materials can be utilized as probable successors for highly efficient active material in photovoltaic utilities.

Universal ve CNC Kontrollü Torna Tezgahlarında FMEA Yöntemiyle Risk Değerlendirme Uygulaması

Developing technology and production needs are increasing the need for the machinery metal production sector. On the lathe machine, is one of the most widely used machines in metal production sector, work accidents and serious occupational diseases occur every year. In order to prevent this, it has become a necessity to create an occupational safety culture in general. In order to prevent the existing hazards and possible accidents in small and large enterprises in the sector, it is necessary to identify them first and to make an effective risk assessment in order to offer solutions. When making a risk assessment, it becomes clear that the risk arising from a hazard in any machine cannot be ignored, that all dangerous situations should be revealed in detail and necessary solutions should be proposed accordingly. In this study, the existing hazards and risks in terms of occupational health and safety of universal and CNC lathes used in a university laboratory were revealed, risk assessment was carried out with Failure Mode and Effects Analysis (FMEA) method and risk priority numbers were calculated. While 6 important risks and 4 fundamental risks were determined for the universal lathe, 1 possible risk, 5 important risks and 1 essential risk were determined for the CNC lathe. According to these results, corrective actions were determined to prevent hazards and solution suggestions were presented. We think that this study will make positive contributions to occupational health and safety in the use of lathes, which are both in manufacturing workshops and used for educational purposes in laboratories.

First-principles study of the contact resistance and optoelectronic properties of PdSe2/MoTe2 van der Waals heterostructure optoelectronic devices

In this study, density functional theory (DFT) calculations are carried out to investigate the contact barriers with different electrodes (Sc, Al, Ni, Pd), transport properties, and light-absorption characteristics of the PdSe2/MoTe2 van der Waals (vdW) heterostructure. The lower n-type Schottky barriers of Sc-PdSe2 and Pd-MoTe2 are demonstrated. The mechanism of interlayer contact of Sc, Al-PdSe2, and Pd, Ni-MoTe2 is confirmed by the following analysis. First, the interlayer charge transfer to form an electric dipole, and the presence of an interfacial dipole, is shown to lead to changes in the metal work function and the band structure off-sets of PdSe2, MoTe2, thus changing the Schottky barrier height (SBH). Second, from the interfacial density of states (DOS) analysis, we demonstrate the strong hybridization of metal interface atoms with monolayer 2D material interlayer atoms, explaining the generation of gap states. In the end, the heterostructure inter-TMDs charge-transfer optical transition mechanism of the MoTe2 VBM to the PdSe2 CBM is demonstrated from the electronic structure analysis of the PdSe2/MoTe2 heterostructure. The low contact resistance and high light absorption explain the excellent performance of PdSe2/MoTe2 heterostructure optoelectronic devices. This work can provide theoretical guidance for designing next-generation electronic and optoelectronic devices.

Biocatalytic synthesis of dioctyl sebacate in toluene using an immobilised lipase

Sebacic esters have excellent lubricity, thermal stability, and biodegradability and therefore are widely used as aerospace lubricants, metal working oil, or engine oil. They are mainly produced by chemical synthesis which, however, may cause environmental pollution, its enzymatic synthesis represents a more environmentally friendly alternative. A few reports have described the synthesis of sebacic esters employing immobilised lipases, but these biocatalytic reactions were exclusively carried out in solvent-free systems and thus, could have been limited by slow reaction rates and high reaction temperatures due to poor enzyme dispersion, low substrate solubility, and high viscosity of the reaction mixture. The current study investigated the biosynthesis of dioctyl sebacate in toluene by Novozym 435, a commercial immobilised lipase. The reaction parameters were investigated using the single factor approach and an orthogonal array design. The optimal conditions obtained were as follows: 10 mL toluene, sebacic acid,1 mmol (202.25 mg); molar ratio of sebacic acid to 1-octanol, 1:3; Novozym 435, 0.03 g; 4 Å molecular sieves, 1.5 g; reaction temperature, 40 °C; reaction time, 30 h. A dioctyl sebacate conversion rate of 93% was achieved under these optimal conditions. In particular, the addition of molecular sieves to the reaction mixture markedly improved the product yield. The reaction temperature was low enough to make the operation easy and energy-efficient and therefore, well suited for large-scale production.

Study of Oil Particle Concentration Vertical Distribution of Various Sizes under Displacement Ventilation System in Large-Space Machining Workshop.

The widespread use of metal working fluids (MWFs) in machining processes leads to the production of a large number of harmful oil particles, which may pose serious health hazards to workers. The oil particle concentration has an inhomogeneous distribution in large spaces under displacement ventilation (DV) system, and the supply air volume required to maintain a low particle concentration under a DV system may be less than that needed under a mixing ventilation system. In this study, computational fluid dynamics (CFD) was used to study the particle concentration distribution rules and characteristics under various particle sizes in a large-space machine workshop with a DV system. Several distribution indices, such as the inhomogeneity factor and stratification height were utilized to analyze the inhomogeneous distribution of particle concentration; furthermore, sensitivity analyses were conducted for these indices. We found that the particle concentration shows a similar inhomogeneity factor distribution rule along the vertical direction under an air change rate of 2–6 in the DV system. The workspace inhomogeneity factor of particles smaller than 5 μm is less than 0.25, whereas that of 10-μm particles declines with an increase in air supply volume. Approximately double the supply air volume is required to keep the 10-μm particle concentration at the same level as particles smaller than 5 μm. The workspace inhomogeneity factor of small particles (<5 μm) is more sensitive to the machine height and machine surface temperature than other parameters, whereas that of large particles (>5 μm) is more sensitive to the supply air volume than other parameters. The results of this study can be applied for the design and control of displacement ventilation systems in large-space machining workshops.

Revealing the weak Fermi level pinning effect of 2D semiconductor/2D metal contact: A case of monolayer In2Ge2Te6 and its Janus structure In2Ge2Te3Se3

Schottky barrier height (SBH), an energy barrier exists at the contact interface between two-dimensional (2D) semiconductor and metal electrode, plays a pivotal role in realizing high device performance. However, the SBH regulation by varing the metal work function is often blocked by the Fermi level pinning (FLP) effect. Herein, based on the density functional theory calculations, we reveal a weak FLP between monolayer In2Ge2Te6 (or Janus In2Ge2Te3Se3) and a series of 2D metals with the work functions spanning around 2 eV. This weak FLP at 2D/2D interface is mainly governed by the potential step between the metal side and semiconductor side in the junctions, which can be evidenced by the good agreement between the modified SBH and the Schottky-Mott limit. In particular, the potential step and its associated interface dipole (or net dipole) presents a linear proportional relationship for In2Ge2Te6-based junctions (or Janus In2Ge2Te3Se3-based junctions) with a slope of ca. 4. The mirror symmetry breaking of Janus In2Ge2Te3Se3 leads to a weaker FLP of Se side than that of Te side owing to the synergistic effect of interface dipole and intrinsic dipole. Therefore, the dipole strength in such 2D/2D junctions can be identified as a target feature of designing low resistance contact, which provides the guidance for reducing the FLP to obtain the tunable SBH and improving the device performance.