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Roll-to-roll (R2R) slot-die coating of polymer electrolyte membrane fuel cell (PEMFC) catalyst layers represents a scalable deposition method for producing 10-20 m2·min-1 of catalyst-coated gas diffusion layers (GDLs). This high-throughput production technique will help lower the cost of PEMFC catalyst layers. The uniformity of the wet layer applied by slot die deposition is affected by process parameters such as substrate speed, vacuum pressure applied at the upstream meniscus, gap between the slot die lips and substrate, ink rheology, and other ink and substrate properties. The set of conditions for producing a defect-free coating with a dilute ink typically requires little to no upstream vacuum pressure, so suitable operating conditions can be found easily through trial and error and operator intuition. However, the higher viscosity of more concentrated inks dramatically shifts the range of settings that result in a homogeneous coating to higher vacuum levels, which are harder to find through hit or miss. A predictive model showing the range of operable conditions decreases material wastage inherent in experimentally searching for suitable parameters. In this study, the defect-free coating parameter window is explored experimentally and theoretically for two concentrations of PEFC cathode inks. Both a full capillary hydrodynamic model and a computationally cheaper viscocapillary model successfully predict the experimentally determined coating window within the experimental and model uncertainty limits for inks with 5.3 wt.% and 12.0 wt.% solids ink while maintaining the 0.1 mgPt·cm-2 Pt areal loading target. This paper demonstrates a viable pathway for meeting the $30/kWnet ultimate cost target of the United States Department of Energy (U.S. DOE) Hydrogen Fuel Cells Technologies Office (HFTO). The concentrated ink lowers the thermal energy and capital expenditure (CapEx) budget of the coating process by decreasing the amount of time, energy, and floorspace required for drying the coating.

In order to seek potential buffer layer, the influence of different vacuum annealing levels on physical properties to e-beam evaporated Zinc Selenide (ZnSe) thin films are meticulously investigated herein. The X-ray diffraction patterns of vacuum-annealed ZnSe films confirmed the prominent (111) reflection of the cubic phase where the crystallite size is found maximum (29 nm). The wavy optical transmittance spectra are observed for these ZnSe films, where higher transparency is observed in the visible region. A blue shift in the optical band gap (2.56–2.81 eV) and shrink in refractive index from 2.49 to 2.40 is observed with increasing vacuum levels. The HRTEM images demonstrated (111), (220), and (311) orientations of the lattice planes, and EDS patterns confirmed deposition of ZnSe films. The ohmic nature of the analyzed ZnSe thin films is validated by the I–V characteristics where the resistivity is found in the order of 102 Ω-cm for vacuum-annealed and 104 Ω-cm for the pristine films. The AFM images indicated hill-like structures where the roughness is found to vary with vacuum level. The physical properties of ZnSe films are conspicuously tailored by vacuum annealing levels, and the findings recommend the use of ~ 5 × 10−3 mbar vacuum-annealed ZnSe thin films as potential buffer layer to the solar cells.

Two-dimensional Janus monolayers have great potential to solve the increasing energy crisis and environmental pollution. In this work, we mainly study the structural, electronic and photocatalytic properties of InSe based Janus Ⅵ-Ⅲ-Ⅳ-Ⅴ monolayers, i.e. InSe-MQ (M = Si, Ge, Sn; Q = P, As) monolayers via first-principles calculations. Theoretical results reveal that they satisfy dynamic, energetic and mechanic stability. Their band gaps range from 1.76 to 2.28 eV, so that abundant visible light could be absorbed. The band edges of single-layer InSe-MQ except InSe–SiP straddle the redox potential of water, and thus the InSe-MQ monolayers except InSe–SiP are promising water-splitting photocatalysts at pH = 0. Particularly, most of InSe-MQ monolayers still have water splitting ability at less acid conditions with higher pH values. On the other hand, our theoretical results also indicate the band edges of group Ⅵ-Ⅲ-Ⅳ monolayers are to a large extent modified as the vacuum level difference between top and bottom surfaces is included, which has been neglected before and firmly collaborated by recalculations on the band arrangements of explored GaS-SnP and InS–SnP monolayers. Overall, this work not only defines several water-splitting photocatalysts but also paves the way to obtain reliable photocatalytic properties of the large group Ⅵ-Ⅲ-Ⅳ-Ⅴ (Ⅲ = Al, Ga, In; Ⅵ = O, S, Se, Te; Ⅳ = Si, Ge, Sn; Ⅴ = N, P, As) monolayers.

Coriolis Vibratory Gyroscope (CVG) is an inertial rotation rate measurement sensor for inertial navigation applications. The rotation sensitive element is a hemispherical vibrating resonator, made of fused silica. It is forced to vibrate at a particular resonant mode with electrostatic forcing. As the resonator is a glass material its vibration amplitude is limited to the submicron level. An ultra-high vacuum environment is necessary for the resonator to sustain the vibration amplitude. Securing the required vacuum level is critical in sensor development. A detailed analysis has been carried out on the damping forces present at various ambiance conditions, the need for threshold vacuum level, threshold forcing voltage for the resonator, and different ways of degradation of the vacuum level in the sensor capsule. This paper presents an experimental study on the damping forces that appear on the resonator by measuring the Q factor at various vacuum levels, vacuum leak rate through weld joints, securing the vacuum environment, and remedial action to arrest vacuum in the sensor volume. Dedicated test setups have been established to carry out the experimental research work.

An inclusive approach for analysing size dependent field emission properties of silicon nanowires has been presented in the current study. The proposed framework complements the traditionally used method of analysis (using Fowler-Nordheim framework) which takes care of the tunnelling current corresponding to low as well as high electric fields. The present model uses boost factor (which is deduced based on effective work function) and field emission power density as parameters to quantify the field emission in addition to the “field enhancement factor” used previously. Silicon nanowires, obtained using metal induced etching technique, show low turn on voltage, high boost factor and high field emission power for smaller nanostructures due to quantum effects leading to quantization of energy levels thus pushing the effective work function closer to the vacuum level. A new empirical formula, showing a hyperbolic behaviour, has also been proposed to represent and quantify the size dependent field emission power density. Overall, the proposed framework complements the classic Fowler-Nordheim methodology to be used more efficiently for nanomaterials.

Utilization of raw natural fibers is a research topic of interest for achieving low-cost and ecofriendly composite materials with properties including low density and high specific strength. In order to obtain materials with these properties, matrix-reinforcement characteristics should be taken into account, as well as the processing method. Therefore, the aim of this research is the production of epoxy resin biocomposites by using three natural fibers as reinforcement, which helped to stablish the role of compatibility and vacuum level in the material’s mechanical properties. Fique, Fique-cotton and Moriche fibers were molded with epoxy resin at different vacuum pressures, resulting in materials with tensile strengths of 50.7 ± 1.3 MPa and 31.5 ± 0.5 MPa for Epoxy/Fique and Epoxy/Fique-Cotton biocomposites processed under a vacuum pressure of 0.4 bar, respectively. The best result for epoxy/moriche biocomposites was 31.5 ± 0.5 MPa at 0 bar. This demonstrated the differences in fiber-matrix compatibility and that applying high vacuum is not necessarily beneficial for achieving high performance biocomposites, as it is commonly the case for composites manufactured with synthetic fibers.

Influence of microwave–vacuum drying technique on the quality and phytochemical properties of pomegranate peel was studied for the first time through this work. The process parameters (microwave power and vacuum level) for production of high quality dried pomegranate peel were optimized using second order polynomial model with interaction. The influence of process parameters on drying efficiency, important nutritional (total polyphenol, total flavonoids, antioxidant capacity, total anthocyanin, and total hydrolysable tannin, mineral and amino acid analysis) and quality (shrinkage, bulk density, hue angle) attributes were analyzed. The drying experimental runs were performed on varied ranges of microwave power (175 W, 330 W, 485 W) and vacuum pressure (10 kPa, 15 kPa, 20 kPa) using a face‐centered composite design. Analysis of variance displayed that the quadratic model with high R2 values predicted well the experimented result. Optimum drying process parameter values of 276 W (microwave power) and 10 kPa (vacuum level) were suggested for microwave-vacuum drying of pomegranate peels. Distinct validation runs was performed at the obtained optimum parameter values to authenticate the predictions and suitability of the models. The projected responses at optimum condition using RSM were in well agreement with experimental value possessing a small relative deviation level of 0.0141–1.2869. At the optimized condition, the quality and nutritional attributes studied were considerably preserved with the total polyphenol, total hydrolysable tannins, total flavonoid and antioxidant values being 205.68 mg GAE/g of DW, 94.68 mg TAC/g of DW, 50.26 mg QE/g of DW and 67.25% respectively. Ultra high performance liquid chromatography (UHPLC) analysis of optimized dried peels exhibited the retention of 11 amino acids in significant levels with glycine possessing highest concentration 5.936 mg/g, findings stated for first time. Validation of the developed second order polynomial model for the optimized condition and its association with the outcomes produced from the quality analyses, phytochemical analyses, mineral analyses and UHPLC suggest that microwave vacuum drying can be applied as a competent substitute to attain a great value product out of pomegranate peel and in this manner reprocess and valorization to this agro-industrial by-product.

There are several growing methods for graphene. In this study, the growth of graphene-like clusters on the SiC wafers is done by annealing the wafers in a vacuum evaporation system equipped with a heating source accessory. For evaluating the quality of the growth method, the Raman spectra and infrared intensities of graphene-like clusters are studied theoretically and experimentally. For doing the theoretical study, three types of graphene clusters are considered and their Raman spectrum and infrared intensities are found using the Hartree-Fock method. The results show that the geometry of the cluster, and in consequence the geometry-dependent high (low) non-uniformity of charge distribution on the cluster surfaces causes the high (low) infrared intensities. The experimental spectrums are measured and compared with the theoretical ones. An agreement was seen between the experimental and theoretical Raman spectrum when the wave number is less than 1700 Cm-1. It is shown that more accurate temperature control and higher vacuum level of the chamber are essential for using the physical evaporation method for growing the single-layer graphene on the SiC substrate.

Chemical state analysis in X-ray photoelectron spectroscopy (XPS) relies on assigning well-defined binding energy values to core level electrons originating from atoms in particular bonding configurations. Here, we present direct evidence for the violation of this paradigm. It is shown that the C 1s peak due to C-C/C-H bonded atoms from adventitious carbon (AdC) layers accumulating on Al and Au foils splits into two distinctly different contributions, as a result of vacuum level alignment at the AdC/foil interface. The phenomenon is observed while simultaneously recording the spectrum from two metal foils in electric contact with each other. This finding exposes fundamental problems with the reliability of reported XPS data as C 1s peak of AdC is routinely used for binding energy scale referencing. The use of adventitious carbon in XPS should thus be discontinued as it leads to nonsense results. Consequently, ISO and ASTM charge referencing guides need to be rewritten. Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW2016.0358]; Swedish Research Council VR Grant [2018-03957]; Swedish Energy AgencySwedish Energy Agency [51201-1]; VINNOVAVinnova [2019-04882]; Carl Tryggers Stiftelse [CTS 17:166, CTS 15:219, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

Wood is a renewable resource that has been used as a material in appearance products for years. Despite its acceptable mechanical resistance, different modification processes were developed to enhance wood’s hardness and make it an even more durable material. Impregnating wood pores with monomers under vacuum-pressure cycle is a common method for that purpose. However, most implemented processes are long and mostly submerge wood into a monomer formulation (Bethell’s full-cell process). For that, they can be considered wasteful on the quantity of materials used, energy consumed and on process duration. The objective of this paper was to evaluate the parameters that influence the penetration of monomers into the tangential surface of Yellow birch (Betula alleghaniensis Brit.) samples. The analyzed factors were the monomer formulation’s viscosity, the surface temperature, the vacuum level applied to the process, the anatomy of samples, and the absorption time. After impregnation, the weight gain of the samples was calculated. Monomer penetration depth was calculated and visualized using density profiles and micro X-ray tomography imaging. Results showed that using a low viscosity monomer formulation allied to a certain level of vacuum and absorption time can considerably increase the impregnation into the wood.

ZrB2 film plays an important role in microelectronic applications owing to its extremely high-temperature stability, excellent chemical inertness and low resistivity. Unfortunately, its electrical properties are extremely sensitive to microstructure and contaminants such as oxygen in the prepared films. Conventional strategy for the fabrication of low-content oxygen ZrB2 film requires complex ultra-high vacuum (UHV) setups. In analogy to industrial Ti-sublimation pumping, here we conceive a simple method by introducing an assisted Ti cathode sputtering in situ to trap residual gases and contaminants. This method enables high-quality ZrB2 films with low oxygen-content, good crystallinity and minimum resistivity of 265 μΩ cm to be achieved at a modest vacuum level environment without complex UHV devices and intentional substrate heating system.

In this paper, a study of the energy performance of a solar powered vacuum membrane distillation coupled with liquid ring vacuum pump was investigated through various energy evaluation criteria. This analysis was investigated for the twelve months of the year. The results showed that the average daily production varied over the months from 598 to 217 kg/day. The average specific energy consumption, the average gained output ratio and the average energy efficiency were between 671 and 699 kWh/m3, 0.93–1.01 and 56.2–59.3% respectively. The maximum productivity and the best energy performance were that of June which is the month corresponding to the most important solar radiation. In addition, it was observed that vacuum liquid ring pump is characterized by a lower electrical energy consumption, which varies during the year between 4.2 and 7.47 kWh/m3. Besides, the effect of the vacuum level applied and liquid ring temperature on the energy performance was examined. Obviously, the results reveal that while increasing the vacuum, the specific energy consumption decreases. Moreover, it has been demonstrated that using an operating liquid at reduced temperatures reduces the flow rate required to ensure total condensation and decreases energy loss and specific energy consumption.

A novel solid-liquid inter-diffusion (SLID) bonding process is developed allowing to use thin layers of the Au-Sn material in wafer-level microelectromechanical systems (MEMS) packaging while providing a good bonding strength. The bond material layers are designed to have a robust bond material configuration and a metallic bond with a high re-melting temperature, which is an important advantage of SLID bonding or with its alternative name, transient liquid phase (TLP) bonding. The liquid phase in SLID bonding is the gold-rich eutectic liquid of the Au-Sn material system, where the bonding temperature is selected to be 320 °C for a reliable bonding. The average shear strength of the bonds is measured to be 38± 1.8 MPa. The hermeticity of the package is tested with the He-Leak test according to MIL-STD 883, which yields a leak value lower than $0.1 \times 10^{-9}\,\, atm.cm^{\textit {3}}/s$ . The vacuum inside the package without a getter is calculated as 2.5 mbar after cap wafer thinning. The vacuum level is well preserved after post-processes such as annealing at 400 °C and the dicing process. These results verify that thin layers of Au-Sn materials can be used reliably with the SLID or TLP bonding technique using the new approach proposed in this study. [2020-0353]

A high-aspect-ratio and all-silicon wafer-level vacuum encapsulated disk resonant gyroscope (DRG) is designed, fabricated and characterized in this paper. The structure of the DRG is constructed with three layers, the middle active layer is sandwiched by the silicon through silicon via (TSV) layer for electrical interconnect and the silicon cap layer for encapsulation. The bulk silicon fabrication technique is used and the DRG is encapsulated by wafer-level vacuum packaging. The 350 µm height of the (111) silicon wafer is chosen as active layer to increase the pick-off capacitance, the DRG with a high aspect ratio 35:1 is realized by a nonlinear multi-steps silicon deep reactive ion etching (DRIE) recipe. The measured results show the resonant frequency of the DRG for the drive mode and sense mode is 18220.3 Hz and 18228.3 Hz, respectively, with a 8 Hz frequency split. The quality factor is about 17,000 measured by ring-down method. The frequency split and Q value can be further optimized by controlling the fabrication deviation and the encapsulated vacuum level, respectively.

In this work, we report a two-step solvent treatment (TSST) strategy to construct high-performance all-small-molecule solar cells (all-SMSCs) without interfacial layers (IFLs), which only consist of an active layer (AL) sandwiched between two electrodes. The chlorinated ITO (ITO-Cl) anode exhibits down-shifted work functions and improved surface energy enabled by the presence of a large density of chloride ions caused by the surface chlorination of ITO. Moreover, the Al cathode shows elevated vacuum level and reduced interfacial trap density enabled by surface treatment of the active layer with polar methanol. The ITO-Cl/AL/Al-based devices form Ohmic contacts and boost the efficiency of the B1:BTP-eC9 system to 14.86%, which is higher than that of the control device (13.92%) with two IFLs. The use of this TSST strategy in the other two all-small-molecule systems is also confirmed, demonstrating its good generality. This strategy can significantly improve device stabilities, extend the life cycles of ITO substrates, and reduce modules’ production costs.

InP quantum dots (QDs) are considered as the most promising alternative to Cd-based QDs with lower toxicity, and emission spectrum tunability ranging from the visible to near-infrared region. Although high-quality fluorescent InP QDs have been successfully synthesized by several groups, the rigorous synthesis conditions hinder its practical use in display devices. In this work, for the first time, we introduce Zn2+ into the growth stage of the InP QDs to prepare an InP–In(Zn)P core, and then the as-grown InP–In(Zn)P cores were consecutively coated with typical double shells of inner ZnSe and outer ZnS. The final InP–In(Zn)P/ZnSe/ZnS core/shell/shell QDs exhibited a maximum photoluminescence (PL) quantum yield (QY) of 94.3% and have tunable emissions from yellow (569 nm) to red (630 nm), showing a potential application in display devices. Above all, compared with other related studies, the excellent PL properties were obtained in relatively milder conditions (ultimate vacuum level of 400 mTorr). The results of this study provide guidance for the commercial application of InP QDs as a viable alternative to Cd-based QDs.

The breaking of the vertical mirror symmetry in two-dimensional Janus structures has given rise to many outstanding features that do not exist in the original materials. In this work, we study the structural, mechanical, and electronic properties of Janus GeSnX2 (X = S, Se, Te) single-layers using density functional theory. The stability of the investigated Janus structures has been tested through the analysis of their phonon dispersions and elastic parameters. It is found that, with low in-plane stiffness, Janus GeSnX2 single-layers are more mechanically flexible than other two-dimensional materials and their mechanical properties exhibit very high anisotropy. All three single-layers are semiconductors and their bandgap can be altered easily by strain engineering. Due to the asymmetric structure, a vacuum level difference between the two sides is observed, leading to the difference in work function on the two sides of single-layers. Our findings not only provide necessary information about the physical properties of Janus GeSnX2 single-layers but also provide the impetus for further studies on these interesting materials both theoretically and experimentally.

In the past studies have shown that the addition of Ge and Sn into Si lattice to form SiGeSn enhances its carrier mobility and band-gap properties. Conventionally SiGeSn epitaxial films are grown using Ultra-High Vacuum (UHV) conditions with pressures ranging from 10-8 torr to 10-10 torr which makes high volume manufacturing very expensive. On the contrary, the use of low-pressure CVD processes (vacuum levels of 10-2 torr to 10-4 torr) is economically more viable and yields faster deposition of SiGeSn films. This study outlines the use of a cost-effective Plasma Enhanced Chemical Vapor Deposition (PECVD) reactor to study the impact of substrate temperature and substrate type on the growth and properties of polycrystalline SiGeSn films. The onset of polycrystallinity in the films is attributed to the oxygen-rich PECVD chamber conditions explained using the Volmer-Weber (3D island) mechanism. The properties of the films were characterized using varied techniques to understand the impact of the substrate on film composition, thickness, crystallinity, and strain.

Surface functionalisation of diamond can produce negative electron affinity (NEA), where the conduction band lies higher in energy than the vacuum level. Hydrogen termination is well-known to produce NEA on diamond but can be removed by temperatures above ∼700 °C, making it unsuitable for diamond-based thermionic applications, where high temperatures are converted into electricity via an electron emission process. In this review article we give an overview of thermionic emission, describe the potential applications of diamond-based thermionic energy converters, then review the different surface termination schemes that can provide a diamond surface with NEA. We discuss the relative merits of the different NEA surfaces that have been developed both computationally and experimentally as alternative cathode materials for thermionic devices.

Rydberg-like image potential states (IPSs) form special series surface states on metal and semiconducting surfaces. Here, using time-resolved and momentum-resolved multi-photon photoemission (mPPE), we measured the energy positions, band dispersion, and carrier lifetimes of IPSs at the 2H-MoS2 surface. The energy minima of the IPSs (n = 1 and 2) were located at 0.77 and 0.21 eV below the vacuum level. In addition, the effective masses of these two IPSs are close to the rest mass of the free electron, clearly showing nearly-free-electron character. These properties suggest a good screening effect in the MoS2 parallel to the surface. The multi-photon resonances between the valence band and IPS (n = 1) are observed, showing a k‖-momentum-dependent behavior. Our time-resolved mPPE measurements show that the lifetime of photoexcited electrons in the IPS (n = 1) is about 33 fs.

Thermoelectric cooling (TEC) modules are being accomplished in many devices due to their flexible sizing. This application needs a DC to make a cooling effect. In this study, the experiment was focused on the cooling system design using TEC in a vacuum wall. The vacuum wall is known as being well-insulated which helps to reduce the heat load of applications. A cooling box for vaccine preservation was designed in this study, with the inside temperature varied between 17, 19, 21, 23, and 25 °C. Vacuum conditions of −15, −20, and −25 in Hg were used. The results show that the power required decreases when the inside temperature increases. The TEC can control the inside temperature as well, when the outside ambient temperature is slightly different in all testing conditions. The power varies directly with the vacuum level, which shows that the vacuum wall can reduce the heat load from the outside environment. Moreover, the correlation of the power requirement in which the inside temperature can be predicted with good agreement is reported.

In recent years, the selection of engine valves materials is based on high temperature performance, longer maintenance life, prominent creep and corrosion and oxidation resistance. Typical engine valve includes materials like 21-2N and titanium alloys. In order to develop a more suitable material to enhance its performance, new nanodispersion strengthened austenitic stainless steels were developed with and without the addition of Y2O3, Ti and MnN from ferro-alloys (ferro-manganese, ferro-nickel and ferro-chrome) to obtain Fe-21Cr-4Ni-9Mn-0.5C-0.4Si as the required composition through powder metallurgy route. These pre-alloyed powders in proper proportion were milled mechanically within a planetary ball mill to obtain the required composition and nanocrystalline structure. The milled powders were subsequently vacuum hot pressed at 1200 °C and 60 MPa by maintaining it at a vacuum level of 10−3 mbar for a period of 2 h. Vacuum hot pressed samples were subjected to densification and hardness studies, and microstructural analysis and characterization studies. Density of vacuum hot pressed samples was 97.9% when compared to its theoretical density. With the addition of Y2O3 and Ti as minor alloying elements, very fine austenitic grain structure was formed with the formation of Y-Ti-O complex oxides. The presence of chromium-rich precipitates was revealed during SEM–EDS analysis at the grain boundaries which was attributed due to lower cooling rate of austenitic stainless steel. TEM analysis revealed homogeneous distribution of Y-Ti-O complex oxides within the metal matrix. A marginal increase in hot pressed density was reported with the inclusion of Y2O3 and Ti in the austenitic matrix along with 28% increase in hardness values.

Nowadays, technical woven fabrics are broadly utilized as reinforcement of composites. Resin capacity of woven fabric is one of the main challenges in laminate fabrication. Resin diffusion during fabrication of the composite is extremely depended on fabric micro-morphology. The geometry of weave unit cell and its pore are fundamental factors in evaluating resin capacity and resin diffusion within fabrics. The main attempt of this study was obtaining an approach to evaluate resin capacity of a woven fabric via simulating pore shape and pore volume. For this purpose, four basic unit cells for all kind of weaves were simulated with the two shapes of tow cross-section: lens and racetrack. Afterwards, 3D shape and volume of their pores were simulated using this approach. The proposed approach is established on the base of initial data of fabric such as tow setts, tow titers, planar density and thickness of a technical fabric. To assess the simulation, three types of woven fabrics namely, plain, twill and satin were impregnated by epoxy resin using vacuum infusion process. The volume fractions of the matrix and fibers of real composites were compared with simulated ones. It was demonstrated that the approach with racetrack assumption led to high degree of convergence with experimental results. The maximum relative error of pioneered method to evaluate volume of the pore in this condition exceeded up to 1.43 %. Suitable correlation between volume fractions of the pore and void was observed in experimental data. It is experimentally demonstrated that the void volume fraction of composite will be increased with decrease of pore volume due to difficulty of wetting. In this paper, it is illustrated that the resin capacity of a woven fabric is a function of vacuum level in vacuum infusion process. For instance, resin capacity of a certain plain fabric could be reduced up to 10 % under 60 kPa (0.6 bar) of vacuum in contrast with steady state of fabric at room atmosphere.

Traditionally, machine milking is performed at a constant vacuum supply. The system vacuum has to be set high enough to allow a sufficiently high vacuum at the teat end, despite the inevitable vacuum drop caused by milk flow. This leads to an increased vacuum load on the teat, especially when milk flow ceases at the end of milking. We tested the hypothesis that a milk flow-controlled adaptation of vacuum settings during milking allows even higher vacuum levels than are usually recommended during the period of high milk flow if the vacuum is reduced during low milk flow. Combined with a high cluster detachment flow rate level, increased milking performance is expected without an increased effect on teat tissue. Ten Holstein dairy cows were milked with a bucket milker with the claw vacuum adjusted in the absence of milk flow at a regular (43 kPa) and high (48 kPa) claw vacuum, with and without vacuum reduction during low milk flow (

Energy offset at the donor (D)/acceptor (A) interface plays an important role in charge separation in organic photovoltaics. Its magnitude determines the charge separation process under illumination. Extensive studies have been carried out for elucidating the charge transfer (CT) process at different D/A junctions. These works lead to two different views: upon photoexcitation, energies would be (1) consumed in molecular polarization and orientation such that those opposite charges would overcome mutual Coulombic attractive potential at the interface and (2) spent on promoting charges to high-lying delocalized energy states (i.e., hot states), which is necessarily important prior to charge separation. Under these two scheme of studies, the electronic structures and the charge behaviors at the D/A interface should be different under photoexcitation, yet there is so far no direct experimental approach for probing the changes in electronics structures (i.e., Fermi level, vacuum level, frontier molecular orbitals, etc.) upon photoexcitation. Herein, a modified photoelectron spectroscopy (PES) system with an additional solar simulator is used to study the charge distributions and electronic interactions for a standard D/A heterojunction (i.e., copper phthalocyanine (CuPc)/ fullerene (C60)) under photoexcitation. CT states formed as a result of photon energy transfer at the CuPc/C60 junction. Subsequent superpositions of charge transfer and electron polarization effects increase the D/A energy level offsets from 0.75 (ground state measured in the dark) to 1.07 eV (high-lying state measured upon illumination). We showed that there is excess energy consumed for a subtle change in the energy level alignment of the CuPc/C60 junction under illumination, suggesting a new insight for the energy loss mechanism during the photocharge generation processes.

A process to upgrade a biogas product to biomethane has been investigated. Recycling of an absorbent is important for low-cost upgrading of biogas by chemical absorption. This study investigated the alkaline recovery of absorbent solution by thermal decomposition at various temperatures (75, 85 and 95 °C) and various vacuum levels (0.2, 0.4 and 0.6 bar). During heating, CO2 and H2S were released from the absorbent solution, which increased the pH. The highest pH 10.58 was reached for NaHCO3 solution from initial pH 8.86 when treated at 95 °C and 0.6 bar vacuum level (gauge pressure). The mass fraction of CO32− in the solution increased from 0.06 to 0.78. Experiments on H2S removal from NaHS solution gave the highest pH 10.38 at 95 °C and 0.6 bar vacuum pressure. Moreover, the performance of the recovered alkaline solution was tested in biogas absorption. The results show that CO2 and H2S removal efficiencies of alkaline solution before and after recovery were similar, at 80 and 99 % respectively. This study demonstrated that thermal decomposition has high potential for recovering the alkaline used absorbent, for recirculation back into the absorption process.

Purpose The Beijing Electron–Positron Collider II (BEPCII) Linac is powered by 20 klystrons, and the output windows of each klystron need to be protected from being broken, which are currently protected by a system based on reflected radiofrequency (RF) power and vacuum levels. The primary weak point of reflection-based protection is the difficulty of accurately measuring the value caused by an uneven waveform. Moreover, vacuum protection is restricted by the long response time, which results in delayed protection. Both of the weak points may damage the output window of the klystron. An arcing-based protection system is then introduced into the BEPCII Linac, considering the constant presence of light during arcing and the experiences of other laboratories and colleagues in the RF group. Methods The system development mainly consists of the design and test of the E-bend waveguide observation window, selection of the arcing detection module, offline joint test, system assembling and online operation. Results The system was assembled with a new klystron at the K6 position on the summer of 2018. During the following annual operation year, the light signal was captured, and the interlock was successfully realized. Conclusion The arcing-based protection system assembled online was found to work well. Moreover, the light signal was successfully captured, and the interlock function worked fine. The system is planned to be applied in other klystron locations in the future.

In this study, metallurgical grade crude selenium (99.4%), comprehensively recovered from copper electrolysis anode slime, was purified to 99.992% through triple consecutive vacuum distillation (TCVD) on a laboratory scale. The actual evaporation rate and accommodation coefficient α of crude selenium were found to be 0.0231 g cm−2 min and 0.3236, respectively, at 523 K and approximately 4 Pa by a vacuum thermogravimetric furnace. Internal heat vacuum distillation equipment was employed in the purification experiments with a dynamic vacuum level of approximately 4 Pa. Detailed analysis of the initial and purified selenium was performed using inductively coupled plasma mass spectrometry (ICP-MS) to identify the 15 most common impurity elements. The analysis confirmed the reduction in the total impurity content from 2997.38 ppmw to

In the search for new efficient photo-catalysts for hydrogen production through water splitting, the main attention has been paid to tuning the band gap width and its position with respect to vacuum level. However, actual electro-catalytic activity for the water oxidation reaction on a catalyst surface is no less important than those quantities. In this work we evaluate from first principles the thermodynamics of the reaction on relatively new candidates for water splitting: two-dimensional C2N and that doped with phosphorus. We find that the 4-step reaction usually expected for water splitting will not proceed on these systems, resulting in oxygen atoms left strongly adsorbed to the surface. Another option, a 3-step reaction, is also found to be unfavorable. We also test an effect of higher oxygen coverage on the reaction thermodynamics, as suggested elsewhere. We find that, indeed, the doubled O-coverage makes the 4-step reaction feasible for the doped C2N. However, an unacceptably high anode potential is required to make this reaction proceed. We thus conclude that the materials under consideration may not be efficient electro-catalysts for water splitting.

This study was conducted to develop and evaluate the effects of vacuum assisted solar drying on the quality attributes of crush, tear and curl (CTC) black tea. The influence of process parameters on the quality of tea was analyzed by using Design expert 7.1.1 software. The independent parameters namely vacuum level and loading rate were varied as per rotatable central composite design, and the responses were liquor colour (LC), aroma index (AI), drying time (t) and energy consumption (EC). The optimum drying condition was successfully found to be at a vacuum level of 570.71 mmHg and loading rate of 0.96 kg dry solid m−2. The LC redness and yellowness index, AI, t and EC were found to be 20.08, 11.65, 4.44, 140.66 min and 21450.7 kJ respectively in optimized condition. Two individual catechin, namely EGCG (epigallocatechin gallate) and ECG (epigallocatechin); four individual theaflavin like total theaflavins (TF), TF3MG (theaflavin-3-monogallate), TF3’MG (theaflavin-3′-monogallate) and TF3,3’DG (theaflavin-3,3′-digallate) and caffeine were detected in the made tea at the optimized conditions. The predicted optimum drying conditions were in good term with the experimental results obtained. This optimum input parameters obtained from the present study would help to produce quality tea.

This research introduces a novel solid-phase microextraction technology, in which the features of heating of sample, cooling of sorbent, and extraction under vacuum condition have been merged. Heating-, cooling- and vacuum-assisted solid-phase microextraction (HCV-SPME) method was developed as an efficient solution for the direct extraction of volatile and semi-volatiles species in complex solid samples. HCV-SPME was coupled with an in-needle capillary adsorption trap (HCV-INCAT) and applied to the direct extraction of polycyclic aromatic hydrocarbons (PAHs) within soil samples. It consisted of polythiophene/carboxylic acid modified multi-walled carbon nanotube nanocomposite, which was synthesized and wall-coated within a platinized stainless-steel needle via electropolymerization. The influential experimental variables (desorption conditions, sample temperature, adsorption temperature, sampling flow rate, and vacuum level) on the extraction efficiency were optimized. The developed HCV-INCAT technique was used in conjunction with GC-FID and applied for the extraction and determination of PAHs in contaminated soil samples, closely matching with those obtained using a validated ultrasonic-assisted solvent extraction procedure. Under the optimal conditions, linear dynamic ranges, limits of detection, and relative standard deviations were obtained 0.007–5 µg g−1, 8–20 pg g−1, and 7.1–12.1%, respectively, for direct extraction of naphthalene, fluorene, phenanthrene, fluoranthene, and pyrene from solid samples.