Proper Flow Rate Research Articles

Parametric Study of Droplet Formation and Characteristics Within Microfluidic Devices — A Case Study

Droplet-based microfluidics technologies hold great attention in a wide range of applications, including chemical analysis, drug screening, and food industries. This work aimed to describe the effects of different physical properties of the two immiscible phases on droplet formation in a flow-focusing microfluidic device and determining proper flow rates to form a droplet within the desired size range. A numerical model was developed to solve the governing equations of two-phase flow and the results were validated with previous experimental results. The results demonstrate different types of droplet formation regimes from dripping to jetting and different production rates of droplets as a consequence of the impact of each property on fluid flow, including the viscosity ratio, density, interfacial tension, and the flow rate ratio. Based on the results, flow rate, viscosity, and interfacial tension strongly affect the droplet formation regime as well as its size and shape. Droplet diameter increases by increasing the dispersed to continuous phase flow rate as well as the interfacial tension while it decreases by increasing the viscosity ratio and the continuous phase density. Moreover, the formation of satellite droplets was modeled, and the effect of interfacial tension, the viscosity of the dispersed phase and the continuous phase density were found to be important on the conditions that the satellite droplets are suppressed. Since the formation of the satellite droplets induces polydispersity in droplet size, this phenomenon is avoided. Collectively, choosing appropriate aqueous and oil phases with proper physical properties is crucial in forming monodisperse droplets with defined size and shape.

Thermo-Hydraulic Analysis of a Tri-Axial High-Temperature Superconducting Power Cable with Respect to Installation Site Geography

Various high-temperature superconducting (HTS) power cables are being developed or are ready for commercial operation to help energy suppliers meet the growing power demand in urban areas. Recently, triaxial HTS power cables have been developed by Korea Electric Power Corporation (KEPCO) and LS Cable & System. Further, KEPCO has been planning to install a 2 km long 23 kV/60 MVA triaxial HTS power cable to connect the Munsan and Seonyu substations and increase the stability of the power grid. The HTS power cables should be cooled down to a cryogenic temperature near 77 K. A thermo-hydraulic analysis of the cooling system considering the geographical characteristics of the installation site is essential for long-distance sections. This paper describes the thermo-hydraulic analysis of the triaxial HTS power cable to determine the proper mass flow rates of subcooled liquid nitrogen that meet the operating temperature and pressure of the cable for four configurations of cooling systems: (1) a single cooling system with an external return path, (2) a dual cooling system with an external return path, (3) a single cooling system with an internal return path, and (4) a dual cooling system with internal return path. Since the flow characteristics in a corrugated cable cryostat differ significantly from those in a typical annular tube, a computational fluid dynamics (CFD) analysis was conducted to estimate the pressure drop along the cable cryostat. With the CFD analysis and given heat loads in the cable, the temperature and the pressure variations along the cable were calculated and their pros and cons were compared for each configuration of the cooling system. This thermo-hydraulic analysis will be referenced in the actual installation of the HTS power cable between the Munsan and Seonyu substations.

On-chip analysis of magnetically labeled cells with integrated cell sorting and counting techniques

In studies on cell therapies, cells often need to be magnetically labeled and then tracked using magnetic resonance imaging (MRI) techniques. To achieve good imaging performance on infused cells, the analysis of the sorted, labeled cells before infusion is necessary. Herein, we developed a microfluidic chip to quantitatively analyze magnetically labeled cells. The chip was equipped with a magnetophoresis-based cell sorting function and an impedance-based cell counting function. Using RAW264.7 macrophages, we confirmed the two functions of the chip, obtained the number and the magnetic loading distribution of the sorted, labeled cells, and ultimately demonstrated the broad applications of the chip in rapidly selecting a proper flow rate for the buffer solution in the cell sorting process, determining the total average magnetic loading of the labeled cells for the cell labeling process, and offering a necessary reference for the processing of the sorted cells for high performance in vivo imaging. This work provides an integrated lab-on-a-chip design for quantitatively analyzing magnetically labeled cells and thus can promote MRI-based cell-tracking studies.

Purinoceptors, renal microvascular function and hypertension.

Proper renal blood flow (RBF) and glomerular filtration rate (GFR) are critical for maintaining normal blood pressure, kidney function and water and electrolyte homeostasis. The renal microvasculature expresses a multitude of receptors mediating vasodilation and vasoconstriction, which can influence glomerular blood flow and capillary pressure. Despite this, RBF and GFR remain quite stable when arterial pressure fluctuates because of the autoregulatory mechanism. ATP and adenosine participate in autoregulatory control of RBF and GFR via activation of two different purinoceptor families (P1 and P2). Purinoceptors are widely expressed in renal microvasculature and tubules. Emerging data show altered purinoceptor signaling in hypertension-associated kidney injury, diabetic nephropathy, sepsis, ischemia-reperfusion induced acute kidney injury and polycystic kidney disease. In this brief review, we highlight recent studies and new insights on purinoceptors regulating renal microvascular function and renal hemodynamics. We also address the mechanisms underlying renal microvascular injury and impaired renal autoregulation, focusing on purinoceptor signaling and hypertension-induced renal microvascular dysfunction. Interested readers are directed to several excellent and comprehensive reviews that recently covered the topics of renal autoregulation, and nucleotides in kidney function under physiological and pathophysiological conditions (Inscho 2009, Navar et al. 2008, Carlstrom et al. 2015, Vallon et al. 2020).

Effect of crystalline structure on optical and electrical properties of IWOH films fabricated by low-damage reactive plasma deposition at room temperature

Tungsten and water co-doped indium oxide (IWOH) films were deposited via a low-damage reactive plasma deposition method at room temperature followed by air atmosphere annealing. The structural, electrical, and optical properties of IWOH films with different water flow rates (F H2O ) were systematically investigated before and after annealing. Despite the lower mobility (43.7 cm 2 /V) of IWOH films with high water flow rate (H-F H2O , F H2O ≥ 1.5 sccm) in the as-deposited state, it has increased to 65.2 cm 2 /V, which surpassed IWOH films with low water flow rate (L-F H2O , F H2O < 1.5 sccm) after annealing. Meanwhile, a significant increase in average optical transmittance from 80.9% to 88.8% and from 92.2% to 95.2% in the short wavelength of visible (350–500 nm) and near-infrared region (800–2500 nm), respectively, was obtained for H-F H2O films after annealing. The variation of the optical and electrical properties for IWOH films with different F H2O was attributed to the crystalline structure with a larger crystallite size and lower density of grain boundary. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis revealed that high water flow rate impeded crystallization of IWOH films during reactive plasma deposition, leading to an amorphous structure in the as-deposited state. After annealing, however, the H-F H2O films crystallized and exhibited larger grains than both tungsten-doped indium oxide (IWO) and L-F H2O films. The modified crystalline properties of IWOH films with larger grains hence reducing grain-boundary scattering, which was realized by H-F H2O and annealing treatment, gave rise to enhanced electrical properties without deteriorating optical properties. • Hydrogen-doped indium tungsten oxide was fabricated by reactive plasma deposition at room temperature. • Structural, optical and electrical properties were studied as a function of water flow rate. • Proper water flow rate can enhance the crystalline quality with fewer grain boundary scattering. • The modified crystalline properties with reduced grain boundary led to enhanced mobility.

A minimalist approach for generating picoliter to nanoliter droplets based on an asymmetrical beveled capillary and its application in digital PCR assay

We developed a simple approach to form picoliter to nanoliter monodisperse droplets by controlling the interface of an asymmetrical beveled capillary (ABC), with minimalist device of a beveled capillary and a liquid driving module without the need of additional equipment or external forces. We observed an evident leap decrease effect in droplet size specially existed in a capillary with a beveled outlet interface instead of a conventional flat capillary within proper bevel angle and flow rate range, by which droplets with diameters of 2–5 times the inner diameter of the capillary could be spontaneously generated by surface tension. A preliminary theoretical explanation is given to the mechanism of droplet formation at the capillary beveled interface. Various factors affecting the droplet generation process were studied, including capillary hydrophilicity, bevel angle, beveled outlet size, and inner diameter of the capillary, and dispersed phase flow rate. In the optimized condition range, good linear relationship between the droplet volume and the capillary inner diameter (10–100 μm) were obtained, which could be used to conveniently adjust the droplet volume with an adjustable droplet volume range up to 1000 times. Two types of capillaries made of fused silica and polytetrafluoroethylene (PTFE) were adopted for droplet generation using syringe pump, pneumatic pressure or gravity for liquid driving, with the relative standard deviations of droplet volume in the range of 1%–2%. To demonstrate its feasibility, the ABC approach was applied in digital PCR assay for absolute quantification of nucleic acids and identical result as a commercial instrument was obtained. The present approach has features of simple setup, easy to build without needing special microfabrication, low cost, and convenient to use, and could provide a minimalist solution for generating droplets in routine laboratories to perform single molecule analysis, single cell analysis, high-throughput screening, biochemical assays, and chemical synthesis.

Zeolite Cotton in Tube: A Simple Robust Household Water Treatment Filter for Heavy Metal Removal

It is challenging to develop a low-cost household water treatment (HWT) that simultaneously deliver an effective and robust way for safe and reliable water supply. Here, we report a simple flow-through filter made by zeolite-cotton packing in a tube (ZCT) as low-cost HWT device to remove heavy metal ions from contaminated water. The zeolite-cotton is fabricated by an on-site template-free growth route that tightly binds mesoporous single-crystal chabazite zeolite onto the surface of cotton fibers. As a result, the ZCT set-up with optimized diameter achieves both high adsorption efficiency, proper flow rate, reliable supply and strong stability at the same time. After flowed through the set up packed with 10 g of zeolite-cotton, 65 mL 1000 ppm Cu2+ solution was purified down to its safety limit (<1 ppm). Notably, their efficiency remains unaltered when filtering several ions simultaneously. In a simulated purification process, 8 L of water contaminated by Cu2+, Cd2+ and Pb2+ could be transformed into drinking water and it enables the removal of heavy metals to concentrations of below 5 ppb (μg L−1). We also show that the ZCT can be used for disinfection by introducing Ag-exchanged zeolite-cotton without contaminating the water with Ag ions (<0.05 ppm).

Determination of the Mean Mobility and Estimation of the Mobility Distribution of Aerosols with a Concentric-Cylindrical Electrostatic Precipitator

Concentric-cylindrical electrical condensers, commonly employed in laboratory research work to precipitate charged aerosol particles (electrostatic precipitator, ESP), can also be used to measure the mean electric mobility of the aerosol and to estimate its mobility distribution. A theoretical research has been carried out to describe the performance of an ESP and its application to the determination of aerosol mobility distribution. Two main equations have been derived: the transfer function, i.e. the probability that a particle of a given mobility is transmitted through the ESP; and, from it, the basic equation describing the performance of the precipitator, the penetration–voltage equation. These equations are valid for whatever shape of the flow velocity profile. MonteCarlo simulations have been carried out to compute the penetration–voltage curve and found to be in excellent agreement with the analytical equations. The parameters (geometric mean and standard deviation) of aerosols with lognormal mobility distributions can be estimated with certain accuracy as long as the distribution width is not too large. Finally, the effect of Brownian diffusion (not taken into account in the theoretical model) has been considered in the MonteCarlo simulations and found to be negligible provided that proper ESP geometric dimensions and aerosol flow rate are used.

Contamination of Coupling Glass and Performance Evaluation of Protective System in Vacuum Laser Beam Welding

Vacuum laser beam welding enables deeper penetration depth and welding stability than atmospheric pressure laser welding. However, contaminated coupling glass caused by welding fumes in the vacuum space reduces laser transmittance, leading to inconsistent penetration depth. Therefore, a well-designed protective system is indispensable. Before designing the protective system, the contamination phenomenon was quantified and represented by a contamination index, based on the coupling glass transmittance. The contamination index and penetration depth behavior were determined to be inversely proportional. A cylindrical protective system with a shielding gas supply was proposed and tested. The shielding gas jet provides pressure-driven contaminant suppression and gas momentum-driven contaminant dispersion. The influence of the shielding gas flow rate and gas nozzle diameter on the performance of the protective system was evaluated. When the shielding gas flow was 2.0 L/min or higher, the pressure-driven contaminant suppression dominated for all nozzle diameters. When the shielding gas flow was 1.0 L/min or lower, gas momentum-driven contaminant dispersion was observed. A correlation between the gas nozzle diameter and the contamination index was determined. It was confirmed that contamination can be controlled by selecting the proper gas flow rate and supply nozzle diameter.

Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil

Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min−1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min−1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency.

Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fly ash was used as catalytic support for carbon nanotubes (CNTs) growth by chemical vapor deposition (CVD) due to having ideal compositions (SiO2,Al2O3, and Fe2O3). In this paper, CNTs were synthesized on Ni catalyst/fly ash substrate using CVD method. The influence of parameters (e.g., reaction temperature and gas flow rate) on the carbon yield and structure of the resulting CNTs was on the carbon yield and structure of the resulting CNTs was investigated by thermo-gravimetric analyses, Scanning electron microscopy, and Raman spectroscopy analysis. The results indicated that the growth temperature controlling had a significant effect on the diameter of CNTs. And the proper acetylene and hydrogen flow rate would decrease in defect density and increase in yield of as-grown CNTs on fly ash. Finally, the amorphous carbon on the surface of as-grown CNTs were removed by heating in air. Experimental results showed that the hydrophobic of the annealed CNTs was weak due to introducing functional groups to the surface of CNTs.

(Invited) Microfluidic Electroless Interconnection (MELI) Process for Low-Temperature, Pressureless Chip Stacking Applications

Increasing demands for high-performance miniaturized electronic devices have driven the semiconductor industry toward finer pitch and higher interconnect density. Copper pillar has been widely adopted and is rapid becoming the mainstream bumping technology for high-density interconnections, such as 2.5D and 3D IC packaging. Thermo-compression bonding has been widely used for high-density copper pillar bumps because of its highly accuracy alignment and placement. However, the high heat and high force applied to the components during the bonding process often induce high thermal-mechanical stress that causes severe damage to the devices and low-k dielectric layers. Because the mechanical properties of porous, low-k materials decreases with lower dielectric constants, this issue will become more severe in the future when lower dielectric constant materials are employed. Therefore, it is imperative to develop a low-temperature, low-pressure bonding process. To address this issue, a novel Cu-to-Cu bonding process called microfluidic electroless interconnection has been developed. This novel process forms electroless metal interconnections as a replacement for solders, which eliminates all the reliability concerns involved with soldering. Specifically, the process is able to bond copper pillars at a low temperature without applied any pressure. The operating temperature of the process is around 80 °C, which is considerably lower than most bonding processes. Also, there is no need to apply any bonding pressure throughout the bonding process due to the proposed bonding scheme structure. In this way, the thermo-mechanical stress can be largely reduced to maintain the structural stability of packaging. Furthermore, the most exciting aspect of this new approach is the integration of microfluidic technology with the electroless plating process, which allows to precise control the flow of fluids in and out the stacked chip to achieve better bonding performance. The flow rate can quantitatively determined and the fluid flow can be adjusted for either batch or continuous-flow operations. The main objective of this work was to investigate the feasibility of the microfluidic electroless interconnection process in joining copper pillars as a promising route for a low-temperature, pressureless bonding process. First, the overall plating uniformity across the entire die surface at different stand-off heights of the stacked chips was investigated. Preliminary results demonstrated that, by selecting a proper flow rate, a high level of plating uniformity across the die was obtained regardless of the standoff heights. In addition to the electrolessly bonded joints, when the bonding interface was examined by scanning electron microscopy (SEM) and focus ion beam (FIB), it was confirmed that no voids or seams appeared on the bonding interface between the pillars, indicating that the two electroless Ni layers that grew on the opposite sides had merged completely into a single structure. The growth and bonding mechanism of the electroless interconnection process was investigated and characterized fully. The bonding interface and phosphorus distribution in the electroless Ni bonds were examined by an electron probe micro-analyzer (EPMA) to ascertain the effect of batch and continuous flow processing. Moreover, the results of direct shear test shows that the bond strength of the electroless Ni between the copper pillars was greater than the adhesion strength of the Cr layer. Further, it was found that the process has the ability to compensate not only for non-uniform copper surfaces, but also for the misalignment and height mismatch of copper pillars, which provides a competitive edge over other bonding methods. This innovative low-temperature, pressureless electroless bonding approach shows considerable promise for applications that require low stress and low thermal budget process.

Shear-Induced Encapsulation into Red Blood Cells: A New Microfluidic Approach to Drug Delivery

Encapsulating molecules into red blood cells (RBCs) is a challenging topic for drug delivery in clinical practice, allowing to prolong the residence time in the body and to avoid toxic residuals. Fluidic shear stress is able to temporary open the membrane pores of RBCs, thus allowing for the diffusion of a drug in solution with the cells. In this paper, both a computational and an experimental approach were used to investigate the mechanism of shear-induced encapsulation in a microchannel. By means of a computational fluid dynamic model of a cell suspension, it was possible to calculate an encapsulation index that accounts for the effective shear acting on the cells, their distribution in the cross section of the microchannel and their velocity. The computational model was then validated with micro-PIV measurements on a RBCs suspension. Finally, experimental tests with a microfluidic channel showed that, by choosing the proper concentration and fluid flow rate, it is possible to successfully encapsulate a test molecule (FITC-Dextran, 40kDa) into human RBCs. Cytofluorimetric analysis and confocal microscopy were used to assess the RBCs physiological shape preservation and confirm the presence of fluorescent molecules inside the cells.

Experimental research in rotating wedge-shaped cooling channel with multiple non-equant holes lateral inlet

The heat transfer in a novel smooth wedge-shaped cooling channel with lateral ejection of turbine blade trailing edge is experimentally investigated in both non-rotating and rotating cases. Beside the conventional inlet at the bottom of the channel, an extra coolant injection from 8 lateral non-equant holes is introduced to improve the overall heat transfer. The total mass flow rate ratio (lateral mass flow rate/total mass flow rate) varies from 0 to 1.0. The major inlet Reynolds number and rotation number respectively vary from 10000 to 20000 and from 0 to 1.16. Experimental results show that the lateral inlet decreases local bulk temperature and increases local heat transfer at the middle and the top of the static channel. In rotating cases, the lateral inlet notably improves the heat transfer at the high-radius half channel and compensates the negative effects induced by the rotation. Both intensity and uniformity of heat transfer inside the channel are enhanced while flow resistance decreases with proper mass flow rate ratio of coolant from two inlets. The most satisfactory total mass flow rate ratio is around 2/3. This new structural style of cooling channel has huge potential and provides new direction of heat transfer of turbine blade trailing edge.

Operational Design of Magnetostrictive Inkjet PrintHead

This paper presents the redesign of the first magnetostrictive inkjet printhead (MagJet). The redesign includes the structural redesign and operational redesign. After completing the process successfully, the redesigned MagJet is subjected to testing. The effect of backpressure from a commercial syringe pump is evident. The operating frequency with backpressure reaches up to 1.5 kHz, although that without backpressure is 650 Hz. The droplet size at a frequency of 800 Hz is about 53 μm, less than half of the nozzle size. It can be concluded that various droplets can be made by combining frequency with a proper flow rate. Backpressure prevents the MagJet from air inclusion in the nozzle, so continuous ejection of the droplets are possible.

Variability of vacuum in goat clusters under different controlled conditions of pipeline height, vacuum and pulsation settings and flow rate

Teat-end mean vacuum is directly related to teat health and milking process (liner adhesion on teat, proper flow rate). Moreover, vacuum fluctuations (cyclic and irregular) increase the risk of bacterial transmission from one teat to the other. Goat sector is yet missing references on factors linked with milking machine and animal, which influence teat-end vacuum. A laboratory experimentation was performed using a milking simulation device, used for International Committee for Animal Recording (ICAR) tests. The influence of six different parameters on vacuum levels in cluster was studied: pipeline height, working vacuum, pulsation type, pulsation rate and ratio and flow rate. The data analysis was based on vacuum stability calculation: vacuum loss and cyclic vacuum fluctuations.In high line, due to a complex milk flow in long milk tube, teat-end vacuum fluctuations are about 4kPa higher than in low line. An increase of flow rate also leads to higher vacuum fluctuations. This relation seems to be linear; however, this hypothesis should be confirmed through another specific experiment. Contrary to other publications, in low line, vacuum fluctuations are slightly intensified by alternate pulsation, compared to simultaneous one (+1.3kPa). A farm experiment should be carried out, in order to check these results with real field situation and to analyze the effects of these vacuum fluctuations levels on milking incident frequency and udder health. Vacuum loss analysis reveals that high working vacuum level, especially when associated with low flow rates, may lead to teat-end average vacuum over 38kPa. This point out the interest of reducing overmilking and measuring teat-end vacuum during milking, to help farmers define their proper working vacuum level, with regards to mammary health.

Numerical visualization and optimization on the core penetration in multi-cavity co-injection molding with a bifurcation runner structure

Co-injection molding and multi-cavity molding are common processes for plastic products manufacturing. These two systems are sometimes combined and applied in the manufacture of bifurcation-structure products. However, how the influential factors truly affect the core penetration behavior and the detailed mechanism of core penetration behavior has not yet been fully understood. In this study, it has focused on studying the multi-cavity co-injection system with a bifurcation runner structure. The results showed that when the skin-to-core ratio is fixed (say 72/28), the melt flow behavior of a co-injection system, utilizing the same material for both skin and core, is very similar to that of a single shot injection molding. Specifically, the non-symmetrical bifurcation runner structure will influence the flow behavior greatly and cause the core distribution imbalance between different cavities. However, it is observed that when the flow rate is increased, the core material will occupy more volume space in the upstream portion of the runner and the core penetration distance will be reduced in the flow direction downstream. This feature is very useful to further manipulate the skin/core interface in a multi-cavity system. Moreover, regarding how to improve a poor inter-cavity balance of core material distribution, using a suitable adjustment of the skin-to-core ratio will be greatly helpful. However, the core break-through defect can be a common problem in co-injection molding when an unsuitable skin-to-core ratio is used. To prevent the core break-through defect, increasing the flow rate properly can be one of the good options that we can use. Hence, it is concluded that a suitable adjustment of the skin-to-core ratio and a proper flow rate control can be used to optimize the core material distribution in multi-cavity co-injection molding with a bifurcation runner structure. Lastly, in order to validate the inference and the effectiveness of this proposal to improve the inter-cavity imbalance and core break-through problem, a series of experimental studies were performed. And, all experimental results are in good agreement with those of our numerical predictions to further validate the feasibility of our proposed method to gain a better control of the core material distribution with a bifurcation runner structure in multi-cavity co-injection molding.

Optical and electrical properties of synthesized reactive rf sputter deposited boron-rich and boron-doped diamond-like carbon thin films

Boron-doped diamond-like carbon (B-DLC) and boron-rich DLC thin films have been deposited on n-type silicon and quartz substrates by reactive rf magnetron sputtering process. Boron carbide (B4C) target was used in the deposition. Reducing the boron/carbon ratio was achieved by either using hydrogen gas or by introducing a proper flow rate of methane. Another approach of producing B-DLC thin films was achieved by using low methane\argon ratio (5/40) while sputtering atoms from non-saturated target-surface under various sputtering rf powers. The maximum film graphitization and lowest band gap energy was achieved by applying 100 W power. The Auger electron spectroscopy and Raman shifts were used to investigate the composition of the films. The optical properties were investigated using spectroscopic ellipsometry and spectrophotometer. Furthermore, p-type B-DLC/n-type Si(100) heterojunction diode was fabricated and the I–V characteristics were investigated against the flow rates of methane or the rf power.

High-frequency behavior of FeN thin films fabricated by using reactive sputtering

We investigated high-frequency behavior of FeN thin films prepared by reactive sputtering through ferromagnetic resonance (FMR) and its relationship with the static magnetic properties. The FMR was observed in the frequency range from 2 to 18 GHz in the FeN films fabricated at proper nitrogen flow rate (NFR). In those FeN thin films, a decrease of the saturation magnetization and the corresponding decrease of the FMR frequency were observed as NFR was increased during the deposition. The external field dependences of the FMR frequencies were well fit to the Kittel formula and the Land\'e g-factors determined from the fit were found to be very close to the free electron value. The high-field damping parameters were almost insensitive to the growth condition of NFR. However, the low-field damping parameters exhibited high sensitivity to NFR very similar to the dependence of the hard-axis coercivity on NFR, suggesting that extrinsic material properties such as impurities and defect structures could be important in deciding the low-field damping behavior.

A New Stripping Column Process and Optimization of Its Operation

AbstractRegarding a kind of stripping column that is widely used in the chemical industry and which operates in total cold reflux and without top light product, a new stripping process is suggested. It takes dual feeds of the hot plus the cold feed, by replacing part of the cold reflux with a part of cold feed, resulting in significant reduction of energy consumption and simplification of the overhead vapor route. As no changes on the column body and only a pipe are needed, this new process can be implemented conveniently in retrofitted projects. Further, an optimization study is developed for choosing the proper flow rate of the cold feed and the appropriate column running pressure. An application in a stripper dealing with the pre‐hydrotreating reaction products of an oil catalytic reformer shows that the new process is valid.