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Silicon dioxide is the most important gate oxide dielectric material, and its surface planarization is an important factor in the continuous shrinking of the size of integrated circuits. Developing a novel chemical mechanical polishing auxiliary technique to achieve efficient polishing of oxide wafers is a significant challenge. In this study, a novel in-situ micro-nano bubbles auxiliary method, which used a nano-hydrophobic film to prepare a gas supersaturated slurry that can generate instant in-situ micro-nano bubbles during polishing, was developed for oxide wafers. Compared with conventional slurries, this auxiliary method increased the material removal rate by about 30% and ensured the low surface roughness of the wafer of 0.14 nm. The existence of micro-nano bubbles and the multi-size distribution and zeta potential of the micro-nano bubbles were measured by optical microscope and dynamic light-scattering methods. Then, to investigate the auxiliary mechanism of this in-situ micro-nano bubbles, different analytical methods, such as oxide thickness measurement system, scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy, were used to characterize the sample. The results indicated that during the polishing process, the micro-nano bubbles generated in situ have a good cleaning effect. In addition, the free radicals generated after in-situ micro-nano bubbles burst simultaneously modified the surfaces of the wafer and the pad. The improvement of the adsorption between the wafer and abrasives promoted the chemical reaction between them. After conditioning, the rougher and cleaner pad had a higher mechanical effect. Most importantly, this in-situ micro-nano bubbles auxiliary method has the potential to be applicable to all slurries.

With the demand for manufacturing large (e.g., 450 mm) wafers, problems arise due to temperature increases associated with the chemical mechanical polishing (CMP) process. Various methods have been employed to stabilize the in-situ polishing temperature. The use of a high-temperature slurry can improve the removal rate, but a degradation in surface morphology occurs during the copper CMP procedure. To explain this mechanism, the effects of temperature on the slurry, CMP pad, and copper wafer were separately investigated. A temperature of approximately 40 °C was demonstrated to be a suitable choice when considering polishing efficiency and quality, thereby facilitating the rapid production of semiconductors. Particle aggregation was also observed with a rise in temperature. The work presented here may allow for a reduction in defects during low-hardness material polishing.

Diffusioosmosis (DO) results from ion transport near charged surfaces in the presence of electrolyte gradients and is critical in nanofluidic systems. However, DO has not yet been comprehensively studied because nanofabrication materials have limitations of low throughput and difficult quantification. Herein, we describe a self-assembled particle membrane (SAPM)-integrated microfluidic platform that can modulate the material properties (e.g., zeta-potential) and transport flux of nanopores. We quantify the effect of the zeta-potential on DO by measuring the electrical signals across three different nanopores/nanochannels of the SAPM. We then empirically quantify the effects of the temperature and ionic strength of the electrolytes on DO and reveal a nonlinear relationship with DO-driven ion transport; the ionic strengths govern the DO- or diffusion-effective ion transport phenomena. Finally, we demonstrate DO-driven electric power generation with enhanced performance as a potential application under optimized experimental conditions.

Negative differential resistance (NDR) can be applied to various devices such as reflection amplifiers, relaxation oscillators, and neuromorphic devices. However, the development of NDR photodetectors with uniformity, stability, and reproducibility for use in practical applications is still lacking. Herein, we demonstrate highly reliable NDR photodetectors by constructing a MoS2/p-Si heterostructure. Owing to the formation of a MoS2 layer with uniform thickness by the plasma-enhanced sulfurization process, a 100% yield with high uniformity (peak-to-valley ratio = 1.195 ± 0.065) was achieved for 120 devices. Furthermore, the proposed NDR photodetectors exhibit unprecedented high cycle-to-cycle endurance, which maintains their NDR characteristics through 100 000 consecutive sweeps without operational failure. This work paves the way for the development of a reliable NDR device and reports unprecedented results of high uniformity, reproducibility, and robustness for practical applications.

The detection of toxic metal ions from water is one of the paramount requirements to combat a typical water pollution problem. Herein, we report a simple and rapid solution for the precise detection of mercury which is one of the toxic metals causing the majority of water pollution diseases. We have explored the chemobiologically synthesized silver nanoparticles in mucus matrix of Achatina fulica snails. The silver nanoparticles play a key role in the sensing of heavy metals. The resultant nanobiocomposite samples were subjected to characterization by UV-Vis spectroscopy, FESEM, and XRD. In a preliminary attempt to develop hassle-free on-site screening protocol, such green hybrid systems were endeavored for selective colorimetric detection of mercury in a solution. Colorimetric detection enables cost-effective and simple monitoring of toxic ions accompanied with the advantage of on-site applicability with avoidance of complex instrumentation and ease of analysis with practical usage. Peculiarly, our simple bio-interfacial sensing approach reveals highly selective colorimetric sensor response down to ppb level for mercury ions analyte. Along with mercury, the other metal ions such as Co, As, Zn, Ni, Pb, Cu, and Fe were also tested for sensing to check the cross-sensitivity.

Technological control over ultra-trace level contaminants is important for semiconductor development. Despite technological developments, defects remain in the single wafer wet cleaning process. In this paper, the source of the contamination is explained via trace analytical methods. Fluorine resin materials of polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE) are commonly used in semiconductor equipment. Isopropyl alcohol (IPA) oxidation reactions occur at high temperature below the boiling point due to impurities. IPA changed to different alcohol forms from gas chromatography (GCMS) analysis. The oxygen concentration in the X-ray photoelectron spectroscopy (XPS) results increased and formed new bonds in IPA with fluorine resin. These reactions confirmed that cations were a catalyst from the time-of-flight secondary ion mass spectrometry (TOF-SIMS) results. Representative ions were Fe+, K+, and Na+ with different concentrations for each material.

The octahedral structure of 2D molybdenum disulfide (1T-MoS2 ) has attracted attention as a high-efficiency and low-cost electrocatalyst for hydrogen production. However, the large-scale synthesis of 1T-MoS2 films has not been realized because of higher formation energy compared to that of the trigonal prismatic phase (2H)-MoS2 . In this study, a uniform wafer-scale synthesis of the metastable 1T-MoS2 film is performed by sulfidation of the Mo metal layer using a plasma-enhanced chemical vapor deposition (PE-CVD) system. Thus, plasma-containing highly reactive ions and radicals of the sulfurization precursor enable the synthesis of 1T-MoS2 at 150 °C. Electrochemical analysis of 1T-MoS2 shows enhanced catalytic activity for the hydrogen evolution reaction (HER) compared to that of previously reported MoS2 electrocatalysts 1T-MoS2 does not transform into stable 2H-MoS2 even after 1000 cycles of HER. The proposed low-temperature synthesis approach may offer a promising solution for the facile production of various metastable-phase 2D materials.

The uniform and continuous nickel internal electrode is crucial in high capacity and highly reliable multi-layer ceramic capacitors (MLCCs). However, the mechanism and the key factors that affect the roughness of the electrode have not been investigated thoroughly. Thus, seeking suitable descriptors that describe the most influential element which decides the roughness is required for the logical design of the Ni paste. In this study, we analyzed the surface of nickel powders and compared their electrode roughness in the aspects of the surface carbon species on nickel nanoparticles. As the increase in the relative C–O/C–C and C=O/C–C ratios, the relative electrode roughness of C-Ni-1, C-Ni-2, C-Ni-3, and C-Ni-4 increased from 1.00, 1.29, 1.54 to 2.51. Thus, low contents of C–O and C=O on the surface of Ni particles could improve the uniformity of the electrode. This study suggests a valuable perspective to reveal the decisive component to build the optimum surface of nickel nanoparticles for uniform internal electrodes in MLCCs.

To improve the throughput of microwell arrays for identifying immense cellular diversities even at a single-bacteria level, further miniaturization or densification of the microwells has been an obvious breakthrough. However, controlling millions of nanoliter samples or more at the microscale remains technologically difficult and has been spatially restricted to a single open side of the microwells. Here we employed a stepped through-hole membrane to utilize the bottom as well as top side of a high-density nanoliter microwell array, thus improving spatial efficiency. The stepped structure shows additional effectiveness for handling several millions of nanoliter bacterial samples in the overall perspectives of controllability, throughput, simplicity, versatility, and automation by using novel methods for three representative procedures in bacterial assays: partitioning cells, manipulating the chemical environment, and extracting selected cells. As a potential application, we show proof-of-concept isolation of rare cells in a mixed ratio of 1 to around 106 using a single chip. Our device can be further applied to various biological studies pertaining to synthetic biology, drug screening, mutagenesis, and single-cell heterogeneity.

Flexibile biosensors have a lot of applications in measuring the concentration of target bioanalytes. In combination with its flexibility, electrochemical sensors containing 2D materials have particular advantages such as enlarged area compatibility, transparency, and high scalability. A flexible biosensor was fabricated by direct synthesis of molybdenum disulfide (MoS2) on a polyimide (PI) substrate, which can be used as the working electrode in electrochemistry platforms. The direct formation of 2D-MoS2 on the PI was achieved using plasma-enhanced chemical vapor deposition (PE-CVD). Since the MoS2 provides higher electrical conductivity, the MoS2-Au-PI flexible sensor is able to provide highly sensitive detection of target proteins with a relatively fast response via cyclic voltammetry. To evaluate the high performance of the fabricated sensor, we selected the endocrine-related hormones parathyroid hormone (PTH), triiodothyronine (T3), and thyroxine (T4) as analytes because they are one of the most important markers for the determination of endocrinopathy, however, they are very difficult to quantify. The newly developed biosensor achieved highly sensitive detection of the hormones and could determine their location with high accuracy. In addition, we performed electrochemical measurements of hormones obtained from 30 clinical patients' sera with confirmed agreement and compared with the measurements performed with standard immunoassay equipment (E 170, Roche Diagnostics, Germany).

Metal oxide semiconductors are of great interest for enabling advanced photodetectors. However, operational instability and absence of an appropriate doping technique hinder practical development and commercialization. Here we propose a strategy to dramatically increase the conventional photodetection performance having superior stability in operational and environmental atmospheres. By performing energy band engineering through an octadecylphosphonic acid (ODPA) self-assembled monolayer based doping treatment, the proposed indium-gallium-zinc oxide (IGZO)/p-Si hetero-interfaced devices exhibit greatly enhanced photoresponsive characteristics, including a photo-switching current ratio with a hundredfold increase, and photoresponsivity and detectivity with a 15-fold increase each. The observed ODPA doping effects were investigated through comprehensive analysis with X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and with a Kelvin probe force microscope (KPFM). Furthermore, the proposed photodetectors fabricated at a four-inch wafer-scale, and demonstrate its excellent operation robustness with consistent performance over 237 days and 20,000 testing cycles. This article is protected by copyright. All rights reserved.

Screening target microorganisms from a mutated recombinant library plays a crucial role in advancing synthetic biology and metabolic engineering. However, conventional screening tools have several limitations regarding throughput, cost, and labor. Here, we used the fluid array platform to conduct high-throughput screening (HTS) that identified Escherichia coli 'TesA thioesterase mutants producing elevated yields of free fatty acids (FFAs) from a large (106) mutant library. A growth-based screening method using a TetA-RFP fusion sensing mechanism and a reporter-based screening method using high-level FFA producing mutants were employed to identify these mutants via HTS. The platform was able to cover >95% of the mutation library, and it screened target cells from many arrays of the fluid array platform so that a post-analysis could be conducted by gas chromatography. The 'TesA mutation of each isolated mutant showing improved FFA production in E. coli was characterized, and its enhanced FFA production capability was confirmed.

We report tunable-morphology oriented facile yet scalable route to synthesize 1D (nanorod) and 2D (nanobelt) MoO3 nanostructures at gram scale using conventional as well as sonochemistry assisted sol–gel technique. The structural, morphological and optical properties of the samples can be befittingly altered by varying the synthesis protocol. The resultant orthorhombic MoO3 nanomorphs demonstrated efficient and expeditious photocatalytic degradation of the pollutant dye, Methylene Blue (MB). We have observed that appreciable photocatalytic MB dye-degradation can be accomplished within 30 minutes with high rate constants of 0.0786 min−1 and 0.233 min−1 for rod and belt-like MoO3-nanostructures, respectively. The pilot results indicate that the resultant MoO3 nanomorphs can be potentially used as solar light driven industrial photocatalyst material with their intrinsic photostability.

Various microfluidic devices have overcome many disadvantages common to conventional bioreactor systems by enabling active manipulation of cell-culture conditions, monitoring of cellular responses in high-throughput mode, and extraction of target cells in a relatively rapid and low-cost manner. However, existing microfluidic devices still have limitations, including the complexity of their operation and a lack of availability of dynamic control of the chemical environment. Here, we present a novel microfluidic bioreactor array device capable of not only the stable and dynamic programing of cell-culture environments but also the selective extraction of target cells. This device comprises 64 microchambers in a 16 × 4 array format, and each microchamber is integrated with a robust and nanoporous membrane on one side and an H-shaped entrance on the other. The membrane made of self-assembled particles allowed continuous and sequential delivery of various nutrients containing gene inducers to compartmentalized microbial cells, thereby enabling dynamic cell culturing. Additionally, the H-shaped entrance was used for local and selective blocking of the microchamber by employing UV-curable material, thereby enabling the retrieval of target cells from the device while sequestering nontarget cells in the microchambers. Our results demonstrated that the targeted rare cells could be isolated and separated from a mixture of cells by repeating the extraction procedure. Therefore, we anticipate that this microfluidic bioreactor array device will be widely used for not only screening/extraction but also off-chip postanalyses of various microorganisms.

Herein, we report facile hydrothermal synthesis of hierarchical MoS2 -based nanomorphs (displaying onion-flower-like features) with the primary focus on field-emitter applications. The synthesized nanostructures were characterized physicochemically to understand their basic structural and morphological features. Interesting nanoscale morphological evolution of onion-flower-like MoS2—from plain nanoflowers to those containing seedpods—is observed with the change in hydrothermal reaction time from 9 h to 21 h. Peculiarly, MoS2 nanomorphs with only onion-flower-like morphology displayed lower turn-on field value of 3.7 V/μm as compared to 4.2 V/μm for the nanoflowers containing seedpod-like particles. This might be attributed to the possibility of an easy electron conduction path available for the petals in plain nanoflowers, which may be impeded by the seedpod-like particles in the latter case.

This study investigated the reasons for inhomogeneity in the axial direction during spark plasma sintering (SPS) of a thermoelectric material. Bismuth antimony telluride, a p-type thermoelectric material, was sintered using high current (>200 A). X-ray diffraction and power factor analyses confirmed that the preferred orientation improved with increasing sintering temperature, and the power factor increased linearly with temperature. The temperature gradient from 700 to 725 K at 723 K sintering process, estimated from this unique correlation between sintering temperature and power factor, was five-fold that of the reported values. This extraordinary temperature gradient was presumably generated by the Peltier effect.

The conventional synthesis of two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is low yielding and lack the heterojunction interface quality. The chemical vapor deposition (CVD) techniques have achieved high-quality heterostructure interfaces but require a high synthesis temperature (>600 °C) and have a low yield of heterostructures. Therefore, the large scale and high interface quality of TMDC heterojunctions using low-temperature synthesis methods are in demand. Here, high-quality, wafer-scale MoS2 and WS2 heterostructures with 2D interfaces were prepared by a one-step sulfurization of the molybdenum (Mo) and tungsten (W) precursors via plasma-enhanced CVD at a relatively low temperature (150 °C). The 4 inch wafer-scale synthesis of the MoS2-WS2 heterostructures was validated using various spectroscopic and microscopic techniques. Further, the photocurrent generation and photoswitching phenomenon of the so-obtained MoS2-WS2 heterostructures were studied. The photodevice prepared by the MoS2-WS2 heterostructures at 150 °C showed a photoresponsivity of 83.75 mA/W. The excellent photoresponse and faster photoswitching highlight the advantage of MoS2-WS2 heterostructures toward advanced photodetectors.

This paper reports an increase in the optical reflectivity of two kinds of copolymers used in contact lenses, with different proportions of silicon and fluorine derivatives, when irradiated with 4.1 MeV alpha particles from an 241Am source. The fiber-optic reflectance technique showed that the lens with a higher proportion of silicon and fluorine content and a lower proportion of methyl-methacrylate is more susceptible to alpha radiation. X-Ray photoelectron spectroscopy and Raman spectroscopy have revealed the formation of silicon oxide and carbide species as a result of chain scission and recombination in the 20 μm thick irradiated regions of lens materials. It is presumed that the high (260 eV/nm) linear energy transfer of alpha particles in polymers creates trapped gas “Bubbles”, and the observed increase in the optical reflectivity with increased irradiation time is explained on the basis of diffuse reflectance caused by the scattering of light from the hard surfaces of these “Bubbles”.

Although ceria particles are currently receiving great interest with their unique catalytic and optical properties, the problem of agglomeration is yet to be overcome, which is caused by their high density and surface energy, consequently hampering the practical applications. Herein, a novel method of preparing hierarchical shells of ceria (CeO2) and silica (SiO2) on a polystyrene (PS) core is introduced to control the shape and surface charge of the particle, which give rise to different dispersion conditions. The PS/CeO2/SiO2 hybrid core–shell microspheres provide a wide spectrum of surface charge via adjustment of the thickness of the outermost silica shell from 20 to 40 nm, which sets the isoelectric point (IEP) in the range of 5.1–8.6. Subsequently, the silica shell significantly extends the product’s stability and utilization windows due to the controlled surface charge and affinity between the particle surface and the dispersion medium. The developed multilayered core–shell microspheres and the method of synthesis have great potential for various applications that require sophisticated control of surface properties.

Many recent studies have employed biomimicry to develop practical systems inspired by natural mechanisms. For instance, several attempts have been made to develop an artificial gill system by mimicking plastron mechanisms, which demonstrates the potential for terrestrial animals to breathe under water by extracting dissolved oxygen and discharging carbon dioxide. In this study, we propose a theoretical model for such artificial gill system comprising essential engineering parameters such as the partial pressure of oxygen inside the system, gas permeability, surface area, and the thickness of membranes. We experimentally investigated the effect of each engineering parameter on the oxygen extraction/supply rate and then validated the theoretical model with experimental results. We also applied the same model and engineering guidelines to develop a scaled-up artificial gill system for a stag beetle. The artificial gill system extracts sufficient dissolved oxygen from water, thus demonstrating that stag beetle can survive for more than 60 h in water; however, carbon dioxide accumulates over time. We believe that the established model and supporting experimental results can further advance artificial gill technology, thereby making it possible for humans to breathe under water without using a conventional scuba gear.

Miniaturized and “smart” sensors are required for research in biology, physiology, and biomechanics, and they have extremely important clinical applications for diagnostics and minimally invasive surgery. Fiber optic sensors have been proven to provide advantages compared to conventional sensors and high potential for biomechanical and biomedical applications. They are small, easy to operate, minimally invasive with low risk, more accurate, and inexpensive. This paper reports the design and modeling of a fiber optic force sensor that is capable of measuring compliance for a contact force of up to 1 N. The main objective of this study is to design and model a fiber optic sensor capable of measuring the total force applied on an object. A polydimethylsiloxane (PDMS) elastomer film with a thickness of 1.2 mm is placed between an optical fiber tip and an object, and it is used for measuring the force applied on a rigid element. The compliance of the fiber optic force sensor is measured by recording the response of PDMS elastomer films under different load conditions. We use finite element modeling results as a basis for comparing experimental data. The agreement between theoretical predictions and experimental data is reasonable and within an acceptable range.

We investigated the rheological and mechanical properties of a polypropylene (PP) composite reinforced by microfibrillated cellulose (MFC) fibers, of which the size was fractionated at ca. 24 µm by removing substances such as lignin or hemicellulose out of natural plants to exert the maximum mechanical performance of cellulose fibers. Due to the poor compatibility of MFC with a non-polar hydrophobic PP matrix, the MFC surface was modified through silylation and acetylation to increase its wetting and dispersion characteristics. The content of silylated-MFC could increase up to 30 wt% in the PP composite through large-volume process such as extrusion and injection molding. In addition, all mechanical properties of the silylated-MFC/PP composite were improved compared to untreated MFC/PP, acetylated MFC/PP composite. It was ensured by a strong shear thinning characteristic of the PP composite with silylated MFC content 30 wt% exhibiting a 69% lower viscosity (337 Pa·s at 4.7 s−1) than the neat PP at 180 °C. The same 30 wt% silylated specimens gave a well-dispersed fibrous MFC in PP, providing a tensile modulus (3.09 GPa) and a flexural modulus (3133 MPa), which were 64 and 81% higher than the neat PP, and 16 and 15% higher than the untreated-MFC composites, respectively. The flexural strength and the heat distortion temperature were also increased by 10 and 22%, compared to neat PP, respectively. In the acetylation reaction, the fibril structure of MFC was damaged due to full substitution by acetyl groups, and the reinforcing effect was insignificant as a filler in PP matrix. The developed silylated-MFC/PP composites provided excellent mechanical properties and high-loading processability that would be difficult to achieve by other eco-friendly composite systems.

Triboelectric nanogenerators (TENGs) harvest and convert mechanical energy to electrical energy. TENGs that are transparent and flexible can be applied to various (opto-)electronic devices supporting finger- or pen-based touchscreen inputs. This paper presents a transparent, flexible TENG that harvests mechanical tapping energy (typically discarded) by simple placement on touchscreen devices. The developed TENG consists of flexible and transparent conducting electrodes (FTCE) with high transmittance (> 93%) and low sheet resistance (18.5 Ω/sq), and transparent 3D-hierarchical polydimethylsiloxane (PDMS) with porous pyramid-patterns. In this study, the developed TENG directly powered eight light-emitting diodes (LEDs) by harvesting the mechanical energy produced by tapping with a touch pen while playing a smartphone game. We also used the transparent TENG as a transparent single-electrode-based, self-powered raindrop detection sensor on a window for a smart home. Our results indicate that the proposed TENG can be used not only as an effective mechanical energy harvester for transparent, flexible, and next-generation optoelectronics devices but also as a self-powered sensor for future Internet-of-Things applications.

Flower-like nanostructures of molybdenum disulphide (MoS2) have been effectively synthesised by the hydrothermal method and further doped with nitrogen using varying concentrations of urea. The formed hierarchical nanostructures are characterised by spectroscopy as well as electrochemical techniques. The structural analysis confirms the formation of a hexagonal MoS2 crystal structure. The existence of MoO2/MoO3/MoS2 composites is also observed after heating MoS2 with a lower urea concentration. Surface morphological analysis of all the prepared compositions shows the appearance of flower-like nanostructures formed by the stacking of 20–80 nanosheets to create individual flower petals. Nitrogen doping shows enhancement in the specific capacitance of MoS2 due to an increase in the electronic conductivity. Furthermore, the specific capacitance is enhanced due to the formation of an MoO2/MoO3/MoS2 composite. The highest specific capacitance calculated from the charge–discharge curve for nitrogen-doped MoS2 prepared using 1 : 1 (MoS2 : urea) weight ratio is observed at around 129 (F g−1) at 2 (A g−1) specific current. The nitrogen-doped MoS2 demonstrates almost four-fold enhancement in specific capacitance than pristine nano-shaped MoS2.

Nanostructural modification of two-dimensional (2D) materials has attracted significant attention for enhancing hydrogen evolution reaction (HER) activity. In this study, the nanostructure of TaS2 films was controlled by controlling the Ar/H2S gas ratio used in plasma-enhanced chemical vapor deposition (PECVD). At a high Ar/H2S gas ratio, vertically aligned TaS2 (V-TaS2) films were formed over a large-area (4 in) at a temperature of 250 °C, which, to the best of our knowledge, is the lowest temperature reported for PECVD. Furthermore, the plasma species formed in the injected gas at various Ar/H2S gas ratios were analyzed using optical emission spectroscopy to determine the synthesis mechanism. In addition, the 4 in wafer-scale V-TaS2 was analyzed by x-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, and the HER performance of the as-synthesized TaS2 fabricated with various Ar/H2S ratios was measured. The results revealed that, depending on the film structure of TaS2, the HER performance can be enhanced owing to its structural advantage. Furthermore, the excellent stability and robustness of V-TaS2 was confirmed by conducting 1000 HER cycles and post-HER material characterization. This study provides important insights into the plasma-assisted nanostructural modification of 2D materials for application as enhanced electrocatalysts.

The purpose of this study was to determine the feasibility of using an electrical low pressure impactor (ELPI) for analyzing residual particles in a Si epitaxial growth process chamber and establish an application technique. Prior to experimental measurements, some preliminary works were conducted, including an inlet improvement of a cascade impactor, vacuum fitting fastening and flow rate adjustment, and a vacuum leak test. After that, residual particles in the process chamber were measured during N2 gas purge using an ELPI due to its advantages including the real-time measurement of particles and the ability to separate and collect particles by their diameters. In addition, ELPI could be used to obtain particle size distribution and see the distribution trend for both number and mass concentration. The results of the real-time analysis of the total particle count revealed that the concentration at the endpoint compared to that at the beginning of the measurement by decreased 36.9%. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM–EDS) analysis of collected particles was performed using two types of substrates: Al foil and a Si wafer. The results showed that most particles were Si particles, while few particles had Si and Cl components. ELPI has the clear advantages of real-time particle concentration measurement and simultaneous collection. Thus, we believe that it can be more actively used for particle measurement and analysis in the semiconductor industry, which has many critical micro/nanoparticle issues.

The trade-off between thermal conductivity (κ) and thermal contact resistance (Rc ) is regarded as a hurdle to develop superior interface materials for thermal management. Here a high-temperature skin softening material to overcome the trade-off relationship, realizing a record-high total thermal conductance (254.92 mW mm-2 K-1 ) for isotropic pad-type interface materials is introduced. A highly conductive hard core is constructed by incorporating Ag flakes and silver nanoparticle-decorated multiwalled carbon nanotubes in thermosetting epoxy (EP). The thin soft skin is composed of filler-embedded thermoplastic poly(ethylene-co-vinyl acetate) (PEVA). The κ (82.8 W m-1 K-1 ) of the PEVA-EP-PEVA interface material is only slightly compromised, compared with that (106.5 W m-1 K-1 ) of the EP core (386 µm). However, the elastic modulus (E = 2.10 GPa) at the skin is significantly smaller than the EP (26.28 GPa), enhancing conformality and decreasing Rc from 108.41 to 78.73 mm2 K W-1 . The thermoplastic skin is further softened at an elevated temperature (100 °C), dramatically decreasing E (0.19 GPa) and Rc (0.17 mm2 K W-1 ) with little change in κ, overcoming the trade-off relationship and enhancing the total thermal conductance by 2030%. The successful heat dissipation and applicability to the continuous manufacturing process demonstrate excellent feasibility as future thermal management materials.

The main aim of doping DNA lattices with lanthanide ions (Ln-DNA complex) is to change the physical functionalities for specific target applications such as electronics and biophotonics. Ln–DNA complexes based on a double-crossover DNA building block were fabricated on glass using a substrate-assisted growth method. We demonstrated the structural stability of Ln–DNA complexes as a function of Ln ion concentration by the atomic force microscopy. The Ln ion doping in DNA lattices was examined using a chemical reduction process, and the electrical characteristics of Ln–DNA complexes were tested using a semiconductor parameter analyzer. The structural phase transition of DNA lattices from the crystalline to amorphous phases occurred at a certain critical concentration of each Ln ion. Ln ions in DNA lattices are known to be intercalated between the base pairs and bound with phosphate backbones. When DNA lattices are properly doped with Ln ions, Ln–DNA complexes revealed the complete deformation with chemical reduction process by ascorbic acid. The current increased up to a critical Ln ion concentration and then decreased with further increasing Ln ions. Ln–DNA complexes will be useful in electronics and photonics because of their unique physical characteristics.

A controllable microchemostat can provide an ideal, powerful means to study the growth behavior of microorganisms by improving conventional macroscale chemostat. However, a challenge remains for implementing both continuous growth and active population control of microorganisms at the same time because they keep communicating with nearby culture environments by regulating their metabolism. Here, we present a novel microchemostat that enables reversible bacterial isolation, continuous chemical refreshment, and dynamic physicochemical stimulation. The microchemostat not only controls bacterial growth and subculture conditions in a completely automated and programmed manner but it also makes it possible to manipulate bacterial populations from a single bacterium to an ultrahigh density for long-term subculture periods with ultralow reagent consumption. Moreover, the microchemostat enables in situ measurement and feedback control of bacterial growth and population through various subculture programming modes that are sequentially performed using a single microchemostat over 720 h; to the best of our knowledge, this is the longest microchemostat culture of bacterial cells reported to date. Hence, we ensure that the microchemostat can be further applied to a wide range of microbial studies on a single chip, such as nutrient optimization, genetic induction, environmental selection, high-throughput screening, and evolutionary adaptation.

A compartmentalized microfluidic chamber array that offers not only separate cell culture environments but also independent control of the diffusion of small molecules provides an extremely useful platform for cell cultivations and versatile cellular assays. However, it is challenging to incorporate both cell compartmentalization and active diffusion control in real-time and precise manners. Here, we present a novel nanoscale hydrodynamic film (NHF) that is formed between a solid substrate and a polydimethylsiloxane (PDMS) surface. The thickness of the NHF can be adjusted by varying the pressure applied between them so that the mass transfer through the NHF can also be controlled. These novel phenomena are characterized and applied to develop a compartmentalized microchamber array with diffusion-tunable and solution-switchable chemostat-like versatile bacterial assays. The NHF-based compartmentalization technique is ideal for not only continuous bacterial cultivation by consistently refreshing various nutrient sources but also various diffusion-based microbial assays such as chemical induction of synthetically engineered bacterial cells and selective growth of a specific bacterial strain with respect to chemical environments. In addition, we show that tight compartmentalization protects cells in the chambers, while biofilm formation and nutrient contamination are eliminated by loading a lysis buffer, which typically hinders long-term continuous cultures and accurate microbial assays on a chip. Therefore, we ensure that the NHF-based compartmentalization platform proposed in this work will facilitate not only fundamental studies in microbiology but also various practical applications of microbes for production of valuable metabolites and byproducts in a high-throughput and highly efficient format.

This study investigated the flashback phenomenon coupled with self-excited combustion instability in turbulent premixed bluff-body flames using the pressure fluctuation measurement, high-speed OH-PLIF, and PIV techniques. Previous studies investigating flashback in a bluff-body have found that the flame moves back and forth around the trailing edge of the bluff-body; however, the phenomenon in which the flame propagates beyond the bluff-body has not been sufficiently studied. Therefore, this study focused on understanding a strong flashback, which can damage the upper section of a combustor and which is vulnerable to heat due to flame propagation over the front of the bluff-body. The combustion instability frequency resulting from changes in the combustion length occurred within the range of the resonance frequency of the combustor, thereby confirming that thermal-acoustic combustion instability occurred in the combustor. When the strong flashback occurs, an instantaneous adverse pressure gradient is formed within a combustion instability cycle. Consequently, the generated reverse flow pushed the flame attached at the trailing edge of the bluff-body to the upstream from the bluff-body. The flame propagated rapidly along the side of the bluff-body by the influence of the boundary layer flow and the decreased quenching distance. This propagated flame became the ignition source at the front tip of the bluff-body and generated the flame surface that propagated in all directions; thus, it was found to be the primary cause of the increase in the flashback distance. The flame flashback distance also varied depending on the combustor length and the initial flow condition. An attempt was made to concentrate the measured data of flashback distance under various conditions into a single line, and turbulence intensity and combustion instability frequency were the dominant factors that impacted the flashback distance.

This paper presents experiments showing the response of a diffusion jet flame to acoustic forcing. The experimental results from the Burke–Schumann flame, which is a special case of the diffusion flame, are compared with the analytical results. The flame response is described by comparing the flame surface, flame length, and heat release oscillation measurements with those from reference papers that have calculated the analytical solution. The flame shape depends on both the forcing frequency and the mean input velocity. The flame shape is divided into three types depending on the forcing frequency. The local stagnation point of the flame propagation and the cutting phenomenon are shown with a low-frequency forcing of the test condition. The flame consists of an undulation form when a high forcing frequency is used as the test condition. At a specific frequency, no flame oscillation is seen, even with acoustic forcing. The forcing frequency also affects the flame length. The mean input velocity affects the magnitude of flame surface oscillations. The heat release ratio oscillation shows that both a premixed flame and a diffusion flame act like low-pass filters. The Peclet number's dependence on the flame surface and the response of the heat release both fit well with the analytical results, whereas the Strouhal number's dependence on the flame surface varies slightly from the analytical solution. The heat release rate oscillation is closely connected to the flame surface oscillations.

Innovative colorimetric biosensing platform has been realized by in-situ synthesis of silver nanoparticles in silk-fibroin matrix derived from domesticated silkworm species Bombyx mori. As-synthesized nano-biocomposite dispersion was characterized by UV-Vis spectroscopy and transmission electron microscopy. In a pilot attempt to develop hassle free on-site screening protocol, such green hybrid systems were explored for colorimetric detection of broad range of metal ion targets, viz. toxic heavy metals such as mercury and chromium (which adversely affect hydrosphere, lithosphere, anthroposphere and biosphere) as well as relatively less-toxic metals like copper and iron in a solution. Quite interestingly, our simple biointerfacial-sensing approach reveals highly selective colorimetric sensor response down to ppb level for mercury ions analyte.

In commercial products such as household deodorants or biocides, didecyldimethylammonium chloride (DDAC) often serves as an antimicrobial agent, citral serves as a fragrance agent, and the excipient ethylene glycol (EG) is used to dissolve the active ingredients. The skin sensitization (SS) potentials of each of these substances are still being debated. Moreover, mixtures of DDAC or citral with EG have not been evaluated for SS potency. The in vitro alternative assay called human Cell Line Activation Test (h-CLAT) and Direct Peptide Reactivity Assay (DPRA) served to address these issues. On three independent runs of h-CLAT, DDAC and citral were predicted to be sensitizers while EG was predicted to be a non-sensitizer and also by the DPRA. Mixtures of DDAC or citral with EG at ratios of 7:3 and 1:4 w/v were all positive by the h-CLAT in terms of SS potential but SS potency was mitigated as the proportion of EG increased. Citral and its EG mixtures were all positive but DDAC and its EG mixtures were all negative by the DPRA, indicating that the DPRA method is not suitable for chemicals with pro-hapten characteristics. Since humans can be occupationally or environmentally exposed to mixtures of excipients with active ingredients, the present study may give insights into further investigations of the SS potentials of various chemical mixtures.

The pristine lignin molecules contain multiple reactive hydroxyl [OH] groups, some of which undergo limited polymerization depending on their configuration (aromatic or aliphatic) or conformation. The key issue in lignin-polymerization is to quantify the number of hydroxyl groups in the pristine molecules for subsequent activation to specific lignin-polymer chain lengths or degree of grafting. In this study, using ε-caprolactone (CL) as a reactive solvent, we successfully polymerized CL on the [OH] sites in the kraft lignin macromonomers (LM, Mw = 1,520 g mol−1), which resulted in a thermoplastic lignin-polycaprolactone (PCL) grafted copolymer. We found that the average number of [OH] groups in the LM was 15.3 groups mol−1, and further detected 40–71% of the [OH] groups in the CL bulk polymerization. The degree of polymerization of PCL grown on each [OH] site ranged between 7 and 26 depending on the reaction conditions ([CL]/[OH] and reaction-time) corresponding to 4,780 and 32,600 g mol−1 of PCL chains per a LM. The thermoplastic characteristics of the synthesized lignin-PCL copolymers were established by the melt viscosity exhibiting a shear-thinning behavior, e.g., 921 Pa.s at 180 °C. The thermal stability was remarkable providing a Tid (2% of weight loss) of 230 °C of the copolymers, compared with 69 °C for the pristine lignin.

Line defects such as wrinkles are believed to change the electrical properties of graphene. However, they are often observed in graphene grown via chemical vapor deposition; hence, it is important to study the impact of the substrate condition on graphene quality. In this work, graphene was synthesized on various copper domains with different crystal orientations and surface morphologies. During the synthesis process, three typical crystal orientations were obtained Cu(001), Cu(101), and Cu(111) showing different surface morphologies with various densities of wrinkles. Graphene wrinkles along with copper wrinkles were studied using atomic force microscopy and Kelvin probe force microscopy. The quality of graphene on different crystal orientations and morphologies was evaluated as well. It was found that different crystallographic orientations lead to different degrees of wrinkle and roughness. In addition, these wrinkle defects exhibited characteristic surface potential variations and the density of substrate wrinkles was closely associated with the uniformity of graphene and led to a disordered structure and low crystallinity.

Synthesis of 4,4'-((phenyl)methylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives was successively carried out using Cu doped ZnO nanomaterials. The nanocrystalline Cu-ZnO was obtained by decomposing as-synthesized copper-zinc oxalate intermediate at 520 °C. The prepared Cu-ZnO nanostructured catalyst was characterized with FTIR, X-ray diffraction, field emission scanning electron microscope and electron diffraction techniques. XRD analysis indicates the formation of highly crystalline hexagonal phase of ZnO along with the presence of monoclinic CuO. FESEM photographs shows the existence of plate like structures made up of small spherical shaped particles having size in the range of 30-50 nm. As-synthesized Cu-ZnO was used as heterogeneous catalyst for one pot synthesis of 4,4'-((phenyl)methylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives using phenyl hydrazine, ethyl acetoacetate and aromatic aldehydes. The 3-methyl-1-phenyl-1H-pyrazol-5-ol was obtained as in-situ precursor to the series of bis-pyrazolone derivatives. The progress of reaction was monitored by thin layer chromatography. The obtained organic product was further characterized and confirmed by FT-IR, 1H-NMR, 13C-NMR and HRMS spectroscopic techniques. The Cu-ZnO catalyst confers upto 96% yield of pyrazolone derivatives in ethanol solvent at refluxing condition. The Cu-ZnO catalyst was used successfully up to 5 cycles without much loss of catalytic activity. Overall, the use of environmental friendly Cu-ZnO nano-structures as a heterogeneous catalyst shows higher yield and lower reaction time towards the synthesis of bispyrazolone derivatives by Tandem Knoevenagel/Michael reaction.

This paper reports a novel diffusiophoresis-based particle manipulator for the concentration and extraction on-demand using a nanochannel-integrated microfluidic channel network fabricated by the crack-photolithography. The nanochannel regulates the physiochemical environments in the microfluidic channel by suppressing convection flows, making it possible to produce a long-term and stable concentration gradient of target solutes over the microchannel. This unique feature facilitates the rapid and dynamic manipulation of chemically driven transport of particles by simply switching ionic solutions. As a result, this platform successfully achieved about 330-fold concentration of $1- \mu \mathrm{m}$ -polystyrene particles in 120 min and their extraction in 10 min with a 95% ratio by simply reverting the concentration gradient of the solutions without any electronic power sources and fluidic controllers.