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One of the main challenges arising from hydrogen-rich fuel mixtures is to prevent flame flashback. In typical gas turbines, the fuel is commonly injected through holes in the axial swirler vanes to achieve a high mixing quality. However, this injection method is not perfect and can cause nonhomogeneous mixing regions, so that locally rich fuel clusters can significantly increase flashback propensity. This work aims to establish a link between the local mixing quality of fuel and air and flashback limits obtained experimentally under elevated pressure conditions. The nonreacting experiments have been conducted at an atmospheric mockup test rig and acetone-planar laser-induced fluorescence (PLIF) has quantified the local fuel concentration. Zones of high equivalence ratio are evident close to the center body wall. The near-wall equivalence ratio fields reveal that the critical probability of the local equivalence ratio being greater than the one for perfect premixing is between 20% and 35% for all hydrogen concentrations at the flashback limits observed. A probability of 35% is selected as a critical threshold to derive a correlation between the local and the global equivalence ratio in technical premixing. Even though the correlation is specific to the investigated burner configuration, the presented methodology offers valuable insights into the impact of the local mixing quality on flashback propensity, which can improve flashback prediction models formulated for perfect premixing conditions. [ABSTRACT FROM AUTHOR]

The change in refractive index with respect to temperature (dn/dT) is defined as the thermo-optic coefficient. It varies according to the light wavelength and temperature, so it is a very important physical quantity that influences light propagation. In this study, we observed the metal-insulator transition (MIT) effect of VO2 on the optical properties of VO2 nanofluid and the thermo-optic coefficient of pure ethylene glycol (EG). We prepared two concentrations (1 x 10-3 mol% and 1 x 10-2 mol%) of EG + VO2 nanofluids by dispersing 50-nm VO2 nano-spheres and injecting them into a cubic glass cell (1 x 1 x 4 cm³). The thermo-optic coefficient was measured by counting the number of interference fringe movements with a Michelson interferometer. The thermo-optic coefficient obtained for pure EG agreed with the literature value within 13.3%. Below 60°C, the thermo-optic coefficients of EG + VO2 were smaller than that of pure EG, but they increased rapidly as the temperature increased. Above 60°C, the thermo-optic coefficients of both EG + VO2 nanofluids rapidly changed and showed a peak and valley near 62°C and 67°C, respectively. We used the maximum value of the derivative of the thermo-optic coefficient (d²n/dT²) to obtain the phase transition temperatures of the VO2 nanofluids, which were 64.6°C and 65.0°C in the samples with 1 x 10-3 mol% and 1 x 10-2 mol%, respectively. [ABSTRACT FROM AUTHOR]

Carbon dioxide emissions in gas turbine power generation can be reduced by adding an increasing amount of hydrogen to the existing natural gas-fueled combustion systems. To enable safe operation, more insight on how H2 addition affects turbulent flame speed and other important flame characteristics is needed. In this work, the investigation of hydrogen addition effects on certain flame properties has been carried out in a high-pressure axial-dump combustor at gas turbine relevant conditions. OH planar laser induced fluorescence (PLIF) was applied to retrieve flame front contours and turbulent flame speed. The results show that as the concentration of hydrogen in the fuel mixture increases, turbulent flame speed and flame characteristics change drastically. Two main regimes can be identified: From 0 to 50% vol. Hydrogen, the turbulent flame speed increases weakly in an almost linear fashion, while from 50% vol. to 100% vol. the trend sharply changes and the higher reactivity of hydrogen, combined with a lower Lewis number, cause thermal-diffusive instability and preferential diffusion effects to become increasingly strong, leading to very high burning rates. The presented results help to understand and to define the relevant modifications that are necessary to successfully operate gas turbine combustor systems with high H2 content fuels. [ABSTRACT FROM AUTHOR]

Nowadays, secret keys of networked devices are profoundly attacked by power analysis attacks, caused by the dramatic evolution of statistical analysis with a simple experimental setup. Recently, OpenSSL and CoreBitcoin running on Android and iOS have been broken by power analysis. Moreover, sensors and actuators can also be attacked thereby threatening user's privacy and security. To resolve these challenges, power-analysis-resistant implementations of cryptographic algorithms in networked devices have received a lot of attentions. Masking schemes have been developed to implement secure cryptographic algorithms against side-channel analysis (SCA) attacks. Technically, the firstorder masking method is vulnerable to the second order differential power analysis (2ODPA) attacks, but the current solutions against 2ODPA are expensive to be implemented. Moreover, worse performance will be shown if the cryptographic algorithms include boolean and arithmetic operations. In this paper, we propose a new countermeasure scheme to resist SCA attacks. Our scheme randomizes all the intermediate values of block cipher by encoding functions in the algorithm to lookup table and makes it resistant to power analysis attack. We apply our scheme to the block cipher algorithm, HIGHT. Our protected implementation of HIGHT takes only 1.79 times compared to the straightforward algorithm, and it needs 25 kbytes to store lookup tables in memory. [ABSTRACT FROM AUTHOR]

Recent advances in controlling the cracking phenomena established a novel unconventional fabrication technique to generate mixed-scale patterns/structures with resolution and accuracy comparable to conventional nanofabrication techniques. Here, we adapt our previous cracking-assisted nanofabrication technique (called "crack-photolithography") relying on only the standard photolithography to develop micro/nanofluidic devices with greatly reduced time and cost. The crack-photolithography makes it possible not only to simultaneously produce micropatterns and nanopatterns with various dimensions but also to replicate both of the mixed-scale patterns in a high-throughput manner. Therefore, a microfluidic channel network can easily be fabricated with a nanochannel array that can function as a nanoporous membrane wherever necessary, which basically plays a key role in diffusion-allowed but convection-suppressed microfluidic devices. In addition, the nanochannel array can manipulate the transport of small molecules by adjusting its dimension and/or number at will, so that nanochannel-array-integrated micro/nanofluidic devices prove even more robust and accurate in diffusion control than conventional membrane-integrated microfluidic devices. As an application of such micro/nanofluidic devices, we employed synthetic bacterial cells and found that their genetic induction and expression are dominated by extracellular diffusive microenvironments that were completely engineered using the nanochannel array. Hence, the crack-photolithography could provide innovative fabrication techniques for unprecedented micro/nanofluidic devices that show substantial potential for a wide range of biological and chemical applications. [ABSTRACT FROM AUTHOR]

We present a novel biomolecule sensing method that enables sensitive and selective detection of target analytes as well as simultaneous separation of non-target analytes by utilizing microtubules (MTs) as a molecular carrier and a nanoporous hydrogel membrane (NHM) as a size-based sieve on a microfluidic chip. We functionalized MTs with aptamers, using a streptavidin and biotin linkage, to provide numerous binding sites for specific target analytes. Target analytes captured by the functionalized MTs from a mixture of complex analytes were transported by electrophoresis (EP) and then sieved by the NHM while non-target analytes passed through the NHM because of the size difference between the analytes and nanopores. Subsequently, the concentration and separation of only target analytes was achieved in a continuous and simultaneous manner because of more rapid transportation of MTs by electric fields. In this study, we demonstrated that our method can be used to detect target analytes at femtomolar levels and enrich the initial concentration by 105-106-fold within 10 min in terms of fluorescent signals. We also demonstrated that the method is approximately 10-100 times more sensitive than conventional nanobead-based detection methods in the light of fluorescent signals. For unlabeled target analytes in a real sample, the method can provide a means to obtain well purified and concentrated target analytes in the form of pellets for off-chip detection and analysis. Thus, we believe that using aptamer-functionalized MTs in conjunction with an NHM in the presence of electric fields can be widely utilized to facilitate the detection, concentration, and separation of specific biomolecule analytes on a chip. [ABSTRACT FROM AUTHOR]

Microfluidic devices utilize ion concentration polarization (1CP) phenomena for a variety of applications, but a comprehensive understanding of the generation of ICP is still necessary. Recently, the emergence of a novel single channel ICP (SC-ICP) device has stimulated further research on the mechanism of ICP generation, so that we developed a 2-D model of an SC-ICP device that integrates a nanoporous membrane on the bottom surface of the channel, allowing bulk flow over the membrane. We solved a set of coupled governing equations with appropriate boundary conditions to explore ICP numerically. As a result, we not only showed that the simulation results held a strong qualitative agreement with experimental results, but alsofound the distribution of ion concentrations in the SC-ICP device that has never been reported in previous studies. We confirmed again that the electrophoretic mobility (EPM) of counterions in die membrane is the most dominant factor determining die generation and strengdi of ICP, whereas the charge density of the membrane was dominant to the ICP strength only when a high EPM value was assumed. From the viewpoint of practical applications, an SC-ICP device with a lorn: membrane under low buffer strength showed enhanced performance in the preconcentration of charged molecules Therefore we believe that the simulation results could not only provide sharp insight into ICP phenomena but also predict and optimize the performance of SC-ICP devices in various microfluidic applications [ABSTRACT FROM AUTHOR]

Many microfluidic devices have been utilizing ion concentration polarization (ICP) phenomena by using a permselective, nanoporous membrane with electric fields for a variety of preconcentration applications. However, numerical analyses on the ICP phenomena have not drawn sufficient attention, although they are an intriguing and interdisciplinary research area. In this work, we propose a 2-D model and present numerical simulation results on the ICP, which were obtained by solving three coupled governing equations: Nernst-Planck, Navier-Stokes, and Poisson. With improved boundary conditions and assumptions, we demonstrated that the simulation results not only are consistent with other experimental results but also make it possible to thoroughly understand the ICP phenomena. In addition, we demonstrated that the preconcentration of analytes can be simulated and quantified in terms of concentration enhancement factors (CEFs) that were related to many factors, such as ionic concentration distribution, electric fields, and flow fields including vortex flows across the membrane. Furthermore, we demonstrated that a high electrophoretic mobility (EPM) of counterions in the membrane plays the most important role in producing accurate simulation results while the effect of the charge density of the membrane is relatively insignificant. Hence, it is believed that the model and simulation results would provide good guidelines to better develop microfluidic preconcentration devices based on the ICP phenomena. [ABSTRACT FROM AUTHOR]

We have developed a novel, microfabricated, stand-alone microfluidic device that can efficiently sort and concentrate (bio-)analyte molecules by using kinesin motors and microtubules as a chemo-mechanical transduction machine. The device removes hundreds of targeted molecules per second from an analyte stream by translocating functionalized microtubules with kinesin across the stream and concentrating them at a horseshoe-shaped collector. Target biomolecule concentrations increase up to three orders of magnitude within one hour of operation. [ABSTRACT FROM AUTHOR]

We present a novel device for the selective extraction and high concentration of biomolecule analytes by integrating microtubules, one of cytoskeletal filaments, with nanofluidic technologies. Microtubules can be functionalized to provide numerous, nanoscopic binding sites for specific target biomolecules. The functionalized microtubules, with the target biomolecules bound to their surface, can be transported in the opposite direction to nontarget molecules using electrokinetic separation. Subsequently, the target molecule-bound microtubules are concentrated by a flat nanochannel structure, which filters the microtubules but allows ionic current and flow to pass through it. This device makes it possible to selectively extract target molecules such as streptavidin and bovine serum albumin and then highly concentrate them up to higher than 5 orders of magnitude from a complex mixture of analytes ranging from 1 nM to 10 fM. In addition, the device performs both extraction (separation) and concentration process simultaneously, which are typically performed in order in other devices, so that we significantly reduce analysis time and labor and even enable preconcentrated, identified target molecules to be available for postanalysis. Thus, we believe that the use of functionalized microtubules with nanofluidics will be a useful means to facilitate biochemical analysis systems. [ABSTRACT FROM AUTHOR]

The direction of translocation of microtubules on a surface coated with kinesin is usually random. Here we demonstrate and quantify the rate at which externally applied electric fields can direct moving microtubules parallel to the field by deflecting their leading end toward the anode. Effects of electric field strength, kinesin surface density, and microtubule translocation speed on the rate of redirection of microtubules were analyzed statistically. Furthermore, we demonstrated that microtubules can be steered in any desired direction via manipulation of externally applied E-fields. [ABSTRACT FROM AUTHOR]

We suggest a concept for powering microfluidic devices with biomolecular motors and microtubules to meet the demands for highly efficient microfluidic devices. However, to successfully implement such devices, we require methods for active control over the direction of microtubule translocation. While most previous work has employed largely microfabricated passive mechanical patterns designed to guide the direction of microtubules, in this paper we demonstrate that hydrodynamic shear flow can be used to align microtubules translocating on a kinesin-coated surface in a direction parallel to the fluid flow. Our evidence supports the hypothesis that the mechanism of microtubule redirection is simply that drag force induced by viscous shear bends the leading end of a microtubule, which may be cantilevered beyond its kinesin supports. This cantilevered end deflects towards the flow direction, until it is subsequently bound to additional kinesins; as translocation continues, the process repeats until the microtubule is largely aligned with the flow, to a limit determined by random fluctuations created by thermal energy. We present statistics on the rate of microtubule alignment versus various strengths of shear flow as well as concentrations of kinesin, and also investigate the effects of shear flow on the motility. [ABSTRACT FROM AUTHOR]

Nanoporous structures are crucial for developing mixed-scale micro-/nanofluidic devices because they facilitate the manipulation of molecule transport along the microfluidic channel networks. Particularly, selfassembled particles have been used for fabricating various nanoporous membranes. However, previous self-assembly mechanisms relied on the material and structural homogeneities of the nanopores. Here, we present a pervaporation-assisted in situ fabrication method that integrates nanoporous membrane structures into microfluidic devices. The microfluidic devices contain a control-channel layer at the top, which induces local and addressable pervaporation, and the main-channel layer, which is present at the bottom with pre-designated locations for nanoporous microchannels; the layers are separated using a gas-permeable film. The target particle suspensions are loaded into the main channels, and their pervaporation is controlled through the gas-permeable film, which successfully assembles the particles at the pre-designated locations. This method yields nanoporous microchannels with various material and structural properties by fabricating heterogeneous nanopore arrays/junctions in series and other diverse structures along the microchannels. We validate the basic working principle of microfluidic devices containing nanoporous microchannels. Furthermore, we theoretically analyze the fundamental experimental results, which suggest the remarkable potential of our strategy to fabricate nanopore networks without using conventional nanofabrication methods. [ABSTRACT FROM AUTHOR]

We present a light-switchable gene expression system for both inducible and switchable control of gene expression at a single cell level in Escherichia coli using a previously constructed light-sensing system. The λ cI repressor gene with an LVA degradation tag was expressed under the control of the ompC promoter on the chromosome. The green fluorescent protein (GFP) gene fused to a λ repressor-repressible promoter was used as a reporter. This light-switchable system allows rapid and reversible induction or repression of expression of the target gene at any desired time. This system also ensures homogenous expression across the entire cell population. We also report the design of a miniaturized photobioreactor to be used in combination with the light-switchable gene expression system. The miniaturized photobioreactor helps to reduce unintended induction of the light receptor due to environmental disturbances and allows precise control over the duration of induction. This system would be a good tool for switchable, homogenous, strong, and highly regulatable expression of target genes over a wide range of induction times. Hence, it could be applied to study gene function, optimize metabolic pathways, and control biological systems both spatially and temporally. [ABSTRACT FROM AUTHOR]

This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is attached. Due to the apparent loss of the true weight of the displacer there is a deflection in the cantilever beam, which causes macro bending in the POF. The loss of intensity due to macro bending of the POF is a measure of the density of the liquid under test. The variation of weight loss with the density of different liquids showed that the weight loss is proportional to density. This sensor is capable of detecting the weight loss with respect to their densities even for liquids having close values of density like distilled water, tap water, and milk of various brands. The resolution of the sensor is observed to be 1.1 mg cm[?]3. [ABSTRACT FROM AUTHOR]

There is an immense need for developing a simple, rapid, and inexpensive detection assay for health-care applications or monitoring environments. To address this need, a photonic crystal (PC)- based sensor has been extensively studied due to its numerous advantages such as colorimetric measurement, high sensitivity, and low cost. However, the response time of a typical PC-based sensor is relatively slow due to the presence of the inevitable upper residual layer in colloidal structures. Hence, we propose an ultra-fast responsive PC-based volatile organic compound (VOC) sensor by using a "nanoscale easy tear (NET) process" inspired by commercially available "easy tear package". A colloidal crystal-polydimethylsiloxane (PDMS) composite can be successfully realized through nanoscale tear propagation along the interface between the outer surface of crystallized nanoparticles and bulk PDMS. The response time for VOC detection exhibits a significant decrease by allowing the direct contact with VOCs, because of perfect removal of the residual on the colloidal crystals. Moreover, vapor-phase VOCs can be monitored, which had been previously impossible. High-throughput production of the patterned colloidal crystal--polymer composite through the NET process can be applied to other multiplexed selective sensing applications or may be used for nanomolding templates. [ABSTRACT FROM AUTHOR]

Subways are used for public transportation as a commuting medium in Korea. Subway trains operate mainly through tunnels. Fine particles generated by friction between rails and train wheels affect the air quality inside a train because the particles enter the ventilation system of the train passing through a tunnel. The PM10 concentration has been mainly used to evaluate indoor air quality, and the PM2.5 concentration has measured recently. Therefore, in this study, the concentrations of the particles entering the air-inlet with respect to particle sizes including 0.1, 1, 2.5 and 10 µm were investigated by using numerical analysis with ANSYS FLUENT software. The particle analysis was performed corresponding to 10, 40 and 80 km/h. It is expected that the numerical results would be helpful in studying the effect of particles corresponding to PM2.5 on the ventilation system, to improve the air quality inside a train passing through a tunnel. [ABSTRACT FROM AUTHOR]

During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C−1 for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures. [ABSTRACT FROM AUTHOR]

The screening and isolation of target microorganisms from mutated recombinant libraries are crucial for the advancement of synthetic biology and metabolic engineering. However, conventional screening tools present several limitations in throughput, cost, and labor. Herein, we describe a novel microfluidic high-throughput screening (HTS) platform with several advantages. The platform utilizes a fluid array to compartmentalize bacterial cells in well-ordered separated microwells and allows long-term cell culture with high throughput. The platform enables the extraction of selected target cells from the fluid array for additional culture and postanalysis by using a capillary-driven sample relocation method. To confirm the feasibility of the platform, we demonstrated two different types of HTS methods based on the levels of reporter gene expression and cellular growth rate difference. For the reporter gene-based HTS, a spike recovery approach was taken to demonstrate that target cells are successfully screened out from a mixture containing nontarget cells by repeating the culture and extraction processes. Additionally, the same platform allowed us to screen and sort target cells according to their cellular growth rate difference, which seems hard in conventional screening methods. Hence, the platform could be used for various microbiological assays, including the detection of cell-excreted metabolites, microbial biosensors, and other HTS systems. [ABSTRACT FROM AUTHOR]

In this study, we report the use of megasonic atomization along with an electric field to reduce the aerosol particle size. The electric field assisted megasonic atomization (EMA) was achieved by implementing mesh and an induction charging ring at the output of a megasonic atomizer. The aim was to increase the number of particles generated and reduce the size of the particles to the nanoscale regime. In the present study, the megasonically generated NaCl and TiO2 aerosols were charged by applying an electric supply voltage up to +20 kV through the induction ring. The generated nanoparticles were evaluated by an electrical low-pressure impactor and scanning electron microscopy. It is observed that, for +15 kV, the number concentration of NaCl and TiO2 particles was found to have increased by up to five times, and the peak size of the particles was shifted from 40nmto 15 nm. The particle size reduction and increase in the number concentration might be due to Coulomb fission. Hence, the developed EMA system is suitable for many industrial applications where a large number of uniform-sized nanoparticles are required. [ABSTRACT FROM AUTHOR]

We report on a cleaning technique using CO2 clusters for large-scale mono-layer graphene fabricated via chemical vapor deposition (CVD) and its application to reduce contact resistance of the CVD graphene device. We found that polymeric residues, i.e., polymethyl methacrylate and photoresist which are generated during transfer and patterning of graphene, can be effectively removed via rapid shrinkage, induced by thermal energy transfer to low temperature CO2 clusters. By applying the CO2 clusters to the cleaning of the interface between metal and graphene, the metal contact resistance of the fabricated graphene field effect transistor was lowered to 26.6% of pristine graphene. The contact resistance shows the best result at an optimized CO2 cluster cleaning condition with a flow rate of 20 l/min, and the resistance was further lowered to 270 Ω μm when a gate bias of -40V was applied. We expect that the proposed CO2 cluster cleaning to be a very promising technique for future device application using 2-dimensional materials, as it can enable low-energy, large-area, high-throughput, and mass-production-compatible process. [ABSTRACT FROM AUTHOR]

The unexpected nuclear accidents have provided a challenge for scientists and engineers to develop sensitive detectors, especially for alpha radiation. Due to the high linear energy transfer value, sensors designed to detect such radiation require placement in close proximity to the radiation source. Here we report the morphological changes and optical responses of artificially designed DNA thin films in response to exposure to alpha radiation as observed by an atomic force microscope, a Raman and a reflectance spectroscopes. In addition, we discuss the feasibility of a DNA thin film as a radiation sensing material. The effect of alpha radiation exposure on the DNA thin film was evaluated as a function of distance from an 241Am source and exposure time. Significant reflected intensity changes of the exposed DNA thin film suggest that a thin film made of biomolecules can be one of promising candidates for the development of online radiation sensors. [ABSTRACT FROM AUTHOR]

New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor. [ABSTRACT FROM AUTHOR]

This paper describes a system to study how small physical perturbations can affect bacterial community behavior in unexpected ways through modulation of diffusion and convective transport of chemical communication molecules and resources. A culture environment that mimics the chemically open characteristic of natural bacterial habitats but with user-defined spatiotemporal control of bacteria microcolonies is realized through use of an aqueous two phase system (ATPS). The ATPS is formulated with nontoxic dextran (DEX) and poly(ethylene glycol) (PEG) dissolved in cell culture media. DEX-phase droplets formed within a bulk PEG-phase stably confine the bacteria within it while small molecules diffuse relatively freely. Bacteria-containing DEX droplets can also be magnetically relocated, without loss of its bacterial content, when DEX-conjugated magnetic particles are included. We found that decreasing the distance between quorum-sensing (QS)-coupled microcolonies increased green fluorescent protein (GFP) expression due to increased inter-colony chemical communication but with upper limits. Periodic relocation of the chemical signal receiver colony, however, increased GFP expression beyond these typical bounds predicted by quorum sensing concepts alone by maintaining inter-colony chemical communication while also relieving the colony of short-range resource depletion effects. Computer simulations suggest that such increased productive output in response to periodic nonlethal physical perturbations is a common feature of chemically activated interactive cell systems where there is also a short-range inhibitory effect. In addition to providing insights on the effect of bacteria relocation, the magnetic ATPS droplet manipulation capability should be broadly useful for bioanalyses applications where selective partitioning at the microscale in fully aqueous conditions is needed. [ABSTRACT FROM AUTHOR]

We present a novel microfluidic device that enables high sensitive analyses of the chemotactic response of motile bacterial cells (Escherichia coli) that swim toward a preferred nutrient by sorting and concentrating them. The device consists of the Y-shaped microchannel that has been widely used in chemotaxis studies to attract cells toward a high concentration and a concentrator array integrated with arrowhead-shaped ratchet structures beside the main microchannel to trap and accumulate them. Since the number of accumulated cells in the concentrator array continuously increases with time, the device makes it possible to increase the sensitivity of detecting chemotactic responses of the cells about 10 times greater than Y-shaped channel devices in 60 min. In addition, the device can characterize the relative chemotactic sensitivity of chemoreceptors to chemoeffectors by comparing the number of cells in the concentrator array at different distances from the channel junction. Since the device allows the analysis of both the chemotactic responses and the sensitivity of chemoreceptors with high resolution, we believe that not only can the device be broadly used for various microbial chemotaxis assays but it also can further the advancement of microbiology and even synthetic biology. [ABSTRACT FROM AUTHOR]

Microfluidic technologies have shown powerful abilities for reducing cost, time, and labor, and at the same time, for increasing accuracy, throughput, and performance in the analysis of biological and biochemical samples compared with the conventional, macroscale instruments. Synthetic biology is an emerging field of biology and has drawn much attraction due to its potential to create novel, functional biological parts and systems for special purposes. Since it is believed that the development of synthetic biology can be accelerated through the use of microfluidic technology, in this review work we focus our discussion on the latest microfluidic technologies that can provide unprecedented means in synthetic biology for dynamic profiling of gene expression/regulation with high resolution, highly sensitive on-chip and off-chip detection of metabolites, and whole-cell analysis. [ABSTRACT FROM AUTHOR]

IL-32 was recently identified as a proinflammatory cytokine that is induced by IL-18 in natural killer (NK) cells and is highly correlated with inflammatory disorders. However, the relationship between IL-32 and tumor progression is still unknown. In this study, we investigated whether overexpression of IL-32 affects susceptibility of chronic myeloid leukemia (CML) cells to NK cells. Interestingly, IL-32α-overexpressing CML cell lines, K562, Kcl22, and BV173, showed higher NK cell-mediated killing. Flow cytometry analysis revealed that overexpression of IL-32α induced increased expression of Fas and UL16-binding protein 2 (ULBP2) in CML cells. The direct relationship between overexpression of surface molecules by IL-32α and increased NK cell-mediated killing was confirmed by Fas or ULBP2 siRNA transfection. IL-32α-induced Fas and ULBP2 expression are regulated p38 MAPK. In addition, the transcription factor Etsi plays a key role in ULBP2 specific expression by IL-32α overexpression in ULBP family members. Taken together) these data show that IL-32α stimulates Fas and ULBP2 expression via activation of p38 MAPK, which increases NK sus- ceptibility of CML cells. Enhanced NI( cell susceptibility of CML cells by IL-32α overexpression may improve the efficiency ófNK cell-based immunotherapy. [ABSTRACT FROM AUTHOR]

Using an aqueous two-phase system comprised of dextran and polyethylene glycol, this article describes the stable spatial patterning of sub-microlitre droplets of bacterial suspensions. Microdroplets of different types of bacterial populations are positioned and maintained adjacent to each other without significant dispersion even though the bacteria are in suspension and not surface bound. Small molecules, in contrast, diffuse relatively freely between the two aqueous phases. The usefulness of these capabilities is demonstrated by generating a small array of suspensions containing different Escherichia colistrains engineered to respond fluorescently or luminescently to different chemical stimuli. When a chemical stimulus is presented, this droplet array produces a pattern of bacterial “illumination” that reflects the type of chemical to which the array was exposed. [ABSTRACT FROM AUTHOR]

Using an aqueous two-phase system comprised of dextran and polyethylene glycol, this article describes the stable spatial patterning of sub-microlitre droplets of bacterial suspensions. Microdroplets of different types of bacterial populations are positioned and maintained adjacent to each other without significant dispersion even though the bacteria are in suspension and not surface bound. Small molecules, in contrast, diffuse relatively freely between the two aqueous phases. The usefulness of these capabilities is demonstrated by generating a small array of suspensions containing different Escherichia colistrains engineered to respond fluorescently or luminescently to different chemical stimuli. When a chemical stimulus is presented, this droplet array produces a pattern of bacterial “illumination” that reflects the type of chemical to which the array was exposed. [ABSTRACT FROM AUTHOR]

In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution by analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements. [ABSTRACT FROM AUTHOR]

This study reports use of inexpensive intensity-based plastic optical fiber (POF) in the form of cantilever beam to monitor the force. The cantilever consists of POF surface bonded on the surface of metal beams viz. spring steel (SS) and mild steel (MS) and subjected to force. The performance of the force sensor is evaluated during macro-bending caused because of the deflection of the beam by applied force. Experimentally obtained detector output of POF, which could be measured with negligible hysteresis is compared with finite element analysis in the range between 0.0098 and 19.613 N. The reproducibility of the sensor is observed in the limit of ±1%. The proposed sensor can replace stain gauge load cell to certain extent in some applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1020–1023, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24217 [ABSTRACT FROM AUTHOR]

Elastomer has become a material of much interest for use as a deformation element in pressure and force monitoring devices. In the present work, we fabricated and characterized a pressure sensor that uses the polydimethylsiloxane (PDMS) elastomer and the plastic optical fiber (POF). The POF is used to guide light through the 10 mm thick PDMS block and collect the transmitted light and deliver it to the detector. In the force sensor, an applied pressure deforms the PDMS block, increasing the transmissivity of the device. The fabricated pressure sensor shows satisfactory response up to 478 kPa with excellent sensitivity and repeatability. The present pressure sensor is simple to fabricate and can be used for a wide range industrial and automobile applications. [ABSTRACT FROM AUTHOR]

DNA molecules doped with lanthanide and metal ions possess distinct functionalities, providing a feasibility to be utilised in various applications in nano- and biotechnologies. In the present work, we fabricate DNA thin films doped with seven different lanthanide ions (Ce3+, Dy3+, Eu3+, Gd3+, Tb3+, Tm3+, and Sm3+) and four different metal ions (Cu2+, Ni2+, Zn2+, and Co2+) by the drop-casting method. In addition, we conduct current, Hall transport, optical transmittance, and Raman spectroscopic measurements to investigate their electrical properties, carrier concentrations and Hall mobilities, optical band gaps, and vibrational and stretching modes, respectively. By analysing the current–voltage characteristics of the doped thin films with varying dopant concentrations, characteristic critical concentrations are observed, which are related to the significant enhancement of the thin film’s physical properties, compared with the pristine DNA. The extrema of the carrier concentrations and Hall mobilities of the doped thin films were observed approximately at the same critical concentrations. The optical band gaps gradually decreased with an increasing dopant concentration, caused by the intrinsic characteristics of both the dopants and DNA. Because of the preference of ions binding to DNA backbones through an electrostatic attraction and to bases via intercalation, the Raman band intensities gradually increase (or decrease) until reaching [Ln]C (or [M]C), where their trend is reversed. Ln-DNA and M-DNA thin films provide significant, specific, and novel physical characteristics which can be used in various applications. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3) has gained immense attention because of its high electron mobility, wide band gap, and excellent optical and catalytic properties. However, the synthesis of uniform and large-area MoO3 is challenging. Here, we report the synthesis of wafer-scale α-MoO3 by plasma oxidation of Mo deposited on Si/SiO2. Mo was oxidized by O2 plasma in a plasma enhanced chemical vapor deposition (PECVD) system at 150 °C. It was found that the synthesized α-MoO3 had a highly uniform crystalline structure. For the as-synthesized α-MoO3 sensor, we observed a current change when the relative humidity was increased from 11% to 95%. The sensor was exposed to different humidity levels with fast recovery time of about 8 s. Hence this feasibility study shows that MoO3 synthesized at low temperature can be utilized for gas sensing applications by adopting flexible device technology. [ABSTRACT FROM AUTHOR]

We fabricated lanthanide ion (Ln3+, e.g. Dy3+, Er3+, Eu3+, and Gd3+)-doped self-assembled double-crossover (DX) DNA crystals grown on the surface of field effect transistors (FETs) containing either a Cr, Au, or Ni electrode. Here we demonstrate the metal electrode dependent FET characteristics as a function of various Ln3+. The drain–source current (Ids), controlled by the drain–source voltage (Vds) of Ln3+-doped DX DNA crystals with a Cr electrode on an FET, changed significantly under various gate voltages (Vg) due to the relative closeness of the work function of Cr to the energy band gap of Ln3+-DNA crystals compared to those of Au and Ni. For Ln3+-DNA crystals on an FET with either a Cr or Ni electrode at a fixed Vds, Ids decreased with increasing Vg ranging from  −2 to 0 V and from 0 to  +3 V in the positive and negative regions, respectively. By contrast, Ids for Ln3+-DNA crystals on an FET with Au decreased with increasing Vg in only the positive region due to the greater electronegativity of Au. Furthermore, Ln3+-DNA crystals on an FET exhibited behaviour sensitive to Vg due to the appreciable charge carriers generated from Ln3+. Finally, we address the resistivity and the mobility of Ln3+-DNA crystals on an FET with different metal electrodes obtained from Ids–Vds and Ids–Vg curves. The resistivities of Ln3+-DNA crystals on FETs with Cr and Au electrodes were smaller than those of pristine DNA crystals on an FET, and the mobility of Ln3+-DNA crystals on an FET with Cr was relatively higher than that associated with other electrodes. [ABSTRACT FROM AUTHOR]

A few-layered molybdenum disulfide (MoS2) thin film grown by plasma enhanced chemical vapor deposition was etched using a CF4 inductively coupled plasma, and the possibility of controlling the MoS2 layer thickness to a monolayer of MoS2 over a large area substrate was investigated. In addition, damage and contamination of the remaining MoS2 layer surface after etching and a possible method for film recovery was also investigated. The results from Raman spectroscopy and atomic force microscopy showed that one monolayer of MoS2 was etched by exposure to a CF4 plasma for 20 s after an initial incubation time of 20 s, i.e., the number of MoS2 layers could be controlled by exposure to the CF4 plasma for a certain processing time. However, XPS data showed that exposure to CF4 plasma induced a certain amount of damage and contamination by fluorine of the remaining MoS2 surface. After exposure to a H2S plasma for more than 10 min, the damage and fluorine contamination of the etched MoS2 surface could be effectively removed. [ABSTRACT FROM AUTHOR]

We studied the physical characteristics of modified-DNA (M-DNA) double crossover crystals fabricated via substrate-assisted growth with various concentrations of four different divalent metallic ions, Cu2+, Ni2+, Zn2+, and Co2+. Atomic force microscopy (AFM) was used to test the stability of the M-DNA crystals with different metal ion concentrations. The AFM images show that M-DNA crystals formed without deformation at up to the critical concentrations of 6 mM of [Cu2+], 1.5 mM of [Ni2+], 1 mM of [Zn2+], and 1 mM of [Co2+]. Above these critical concentrations, the M-DNA crystals exhibited deformed, amorphous structures. Raman spectroscopy was then used to identify the preference of the metal ion coordinate sites. The intensities of the Raman bands gradually decreased as the concentration of the metal ions increased, and when the metal ion concentrations increased beyond the critical values, the Raman band of the amorphous M-DNA was significantly suppressed. The metal ions had a preferential binding order in the DNA molecules with G–C and A–T base pairs followed by the phosphate backbone. A two-probe station was used to measure the electrical current–voltage properties of the crystals which indicated that the maximum currents of the M-DNA complexes could be achieved at around the critical concentration of each ion. We expect that the functionalized ion-doped M-DNA crystals will allow for efficient devices and sensors to be fabricated in the near future. [ABSTRACT FROM AUTHOR]

We demonstrate a facile fabrication of a rich variety of silicon patterns with different length scales by combining polymer lithography and a metal-assisted chemical etching method. Several types of polymer patterns were fabricated on silicon substrates, and silver layers were deposited on the patterned silicon surfaces and used to etch the silicon beneath. Various silicon patterns including topographic lines, concentric rings, and square arrays were created at a micro- and nanoscale after etching the silicon and subsequent removal of the patterned polymer masks. Alternatively, the arrays of sub-30 nm silicon nanowires were produced by a chemical etching of the silicon wafer which was covered with highly ordered polystyrene-block-polyvinylpyridine (PS-b-PVP) micellar films. In addition, silicon nanohole arrays were also generated by etching with hexagonally packed silver nanoparticles that were prepared using PS-b-PVP block copolymer templates. [ABSTRACT FROM AUTHOR]

We present a novel microfabricated concentrator for Escherichia coli that can be a stand-alone and self-contained microfluidic device because it utilizes the motility of cells. First of all, we characterize the motility of E. coli cells and various ratcheting structures that can guide cells to move in a desired direction in straight and circular channels. Then, we combine these ratcheting microstructures with the intrinsic tendency of cells to swim on the right side in microchannels to enhance the concentration rates up to 180 fold until the concentrators are fully filled with cells. Furthermore, we demonstrate that cells can be positioned and concentrated with a constant spacing distance on a surface, allowing spatial patterning of motile cells. These results can be applied to biosorption or biosensor devices that are powered by motile cells because they can be highly concentrated without any external mechanical and electrical energy sources. Hence, we believe that the concentrator design holds considerable potential to be applied for concentrating and patterning other motile microbes and providing a versatile structure for motility study of bacterial cells. [ABSTRACT FROM AUTHOR]