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In this study, we propose an efficient wearable device to continuously and reliably monitor electrocardiogram (ECG) and body impedance (BI) that are two most important bio-signals for healthcare applications. Unlike most conventional systems that fail to synchronously provide a rich set of bio-signals because of their limitation on sensing a single type of signal, the proposed device faithfully analyzes a user's status only using two electrodes. To minimize measurement errors inherently induced by the sensing process caused by using two electrodes and sensing position dependency, we also propose an adaptive system control algorithm that are easy to switch the type of sensing signal and its measurement intervals by changing the setup parameters. Since the size of the device is very small and it is designed with a minimal belt-shape form for maximal user convenience, it is suitable for various types of wearable applications. Experiments performed in a couple of example healthcare scenario demonstrate the reliability of the proposed system.

Magnetization reversal in a GaMnAs trilayer system consisting of two GaMnAs layers separated by a Be-doped GaAs spacer was investigated by magnetotransport measurements. The rotation of magnetization in the two GaMnAs layers is observed as two abrupt independent transitions in planar Hall resistance (PHR). Interestingly, one GaMnAs layer manifests a positive change in PHR, while the other layer shows a negative change for the same rotation of magnetization. Such opposite behavior of the two layers indicates that anisotropic magnetoresistance (AMR) has opposite signs in the two GaMnAs layers. Owing to this opposite behavior of AMR, we are able to identify the sequence of magnetic alignments in the two GaMnAs layers during magnetization reversal. The PHR signal can then be decomposed into two independent contributions, which reveal that the magnetic anisotropy of the GaMnAs layer with negative AMR is predominantly cubic, while it is predominantly uniaxial in the layer with positive AMR. This investigation suggests the ability of engineering the sign of AMR in GaMnAs multilayers, thus making it possible to obtain structures with multi-valued PHR, that can be used as multinary magnetic memory devices.

Many efforts have been invested in the development of rapid and sensitive detection methods for the quantification of disease biomarkers in human blood. Although luminescence- and fluorescence-based detection methods, combined with an automatic sampling system, are routinely used for immunoassays of specific biomarkers, a more sensitive detection technique is needed to track disease progression in its early stage. Recently, a surface-enhanced Raman scattering (SERS)-based immunoassay technique has been considered as a strong candidate to resolve the problem of low sensitivity in conventional luminescence- or fluorescence-based clinical immunoassays. Due to its highly sensitive detection capability and the feasibility of automatic assay, the SERS-based assay technique has strong potential to substitute for currently available fluorescence or luminescence assay systems in clinical laboratory settings. To date, a variety of clinical biomarkers such as proteins, DNAs, hormones, viruses, bacteria, and toxins have been measured using the SERS-based assay technique. Several different types of assay platform have been developed for rapid and reproducible SERS-based assays. In this chapter, four different SERS-based assay platforms—gold-patterned microarray-type substrates, magnetic bead-based assay platforms, microfluidic devices, and lateral flow assay platforms—will be introduced. In addition, the diagnostic feasibility of these assay platforms for various biomarkers will be described.

Phonons in graphitic materials exhibit strong normal scattering (N-scattering) compared to umklapp scattering (U-scattering). The strong N-scattering cause collective phonon flow, unlike the relatively common cases where U-scattering is dominant. If graphitic materials have finite size and contact with hot and cold reservoirs emitting phonons with non-collective distribution, N-scattering change the non-collective phonon flow to the collective phonon flow near the interface between graphitic material and a heat reservoir. We study the thermal resistance by N-scattering during the transition between non-collective and collective phonon flows. Our Monte Carlo solution of Peierls-Boltzmann transport equation shows that the N-scattering in graphitic materials reduce heat flux from the ballistic case by around 15%, 30%, and 40% at 100, 200, and 300 K, respectively. This is significantly larger than ~ 5% reduction of Debye crystal with similar Debye temperature (~ 2300 K). We associate the large reduction of heat flux by N-scattering with the non-linear dispersion and multiple phonon branches with different group velocities of graphitic materials.

The interlayer exchange coupling (IEC) in magnetic multilayers determines the spin orientation of individual magnetic layers comprising the system. The dependence of the resistance on the resulting spin configuration in turn leads to the phenomenon known as giant magnetoresistance (GMR). [1] The GMR effect is of key importance to the area of spintronics, in which the spin degree of freedom is utilized in the operation of electronic devices. The behavior of IEC in metallic ferromagnetic multilayers has been extensively investigated, and the ability to control the IEC by structural parameters to be either ferromagnetic (FM) or antiferromagnetic (AFM) is now well established. In contrast, in multilayers consisting of FM semiconductors such as GaMnAs, the ability to change the IEC from FM to AFM is not well understood. Recently, however, AMF IEC was observed in GaMnAs/GaAs:Be multilayers [1]. These systems, however, show somewhat different behavior from their metallic counterparts. Specifically, the IEC in the GaMnAs/GaAs:Be multilayer system is observed to be long range, typically of over 10 nm, so that not only interactions between nearest neighbor (NN) layers of the multilayer, but also between next-nearest-neighbor (NNN) layers are involved during the magnetization reversal process. [2].

Background & Aims Altered expression of dual specificity phosphatase 1 (DUSP1) is common in tumors including hepatocellular carcinoma (HCC), and is predictive of tumor progression and poor prognosis. However, the tumor suppressive role of DUSP1 has yet to be clearly elucidated. Methods The molecular mechanisms of tumor suppression that were investigated were induction of apoptosis, cell cycle inhibition, and regulation of p53. Additionally, the antitumor effect of DUSP1 was assessed using a mouse model. Associated signaling pathways in HCC cells and tissues were examined. Results Downregulation of DUSP1 expression was significantly correlated with poor differentiation ( p p =0.023). DUSP1 expression resulted in HCC suppression and longer survival ( p =0.0002) in a xenoplant mice model. DUSP1 inhibited p38 MAPK phosphorylation and subsequently suppressed HSP27 activation, resulting in enhanced p53 phosphorylation at sites S15, S20, and S46 in HCC cells. Enhanced p53 activation induced the expression of target genes p21 and p27, which are linked to cell cycle arrest and apoptosis. Thus, DUSP1 was potentially linked to p53 activation via the p38 MAPK/HSP27 pathway. Wild-type but not mutant p53 transcriptionally upregulated DUSP1 via its DNA-binding domain. DUSP1 and p53 might collaborate to suppress tumors in hepatocarcinogenesis via a positive regulatory loop. Conclusions Our results revealed that disruption of a positive regulatory loop between DUSP1 and p53 promoted HCC development and progression, providing a rationale for a therapeutic agent that restores DUSP1 in HCC.

Monitoring periodic limb movements in sleep (PLMS) is important since it is correlated with people's quality of sleep and several other sleep disorders. The clinically approved method of examining PLMS is polysomnography (PSG) where the sleep of patients are examined in a laboratory with various sensors attached to their body. However, PSG is time-consuming and expensive for patients and the need for cost-effective and comfortable PLMS detection method has not been fulfilled. Accordingly, we propose a PLMS detection framework which utilizes a wearable motion-sensor-embedded band. In this work, we study the location to comfortably wear the device and accurately collect data on a foot. Further, to increase the accuracy of classifying PLMS, we propose the Motion Synchronized Windowing technique which segments the intervals where movements occur. Finally, we classify PLMS by using various machine learning algorithms typically used in the human activity recognition. Our proposed system achieves the accuracy of up to 96.92% in detecting PLMS. Therefore, our system is a cost-effective and convenient method of monitoring PLMS.

We investigate the process of selectively manipulating the magnetization alignment in magnetic layers in the Fe/GaAs/GaMnAs structure by current-induced spin-orbit (SO) magnetic field. The presence of such fields manifests itself through the hysteretic behavior of planar Hall resistance observed for two opposite currents as the magnetization in the structure switches directions. In the case of the Fe/GaAs/GaMnAs multilayer, hystereses are clearly observed when the magnetization switches direction in the GaMnAs layer, but are negligible when magnetization transitions occur in Fe. This difference in the effect of the SO-field in the two magnetic layers provides an opportunity to control the magnetization in one layer (in the presence case in GaMnAs) by a current, while the magnetization in the other layer (i.e., Fe) remains fixed. Owing to our ability to selectively control the magnetization in the GaMnAs layer, we are able to manipulate the relative spin configurations in our structure between collinear and non-collinear alignments simply by switching the current direction even in the absence of an external magnetic field.

Background Scrub typhus is an acute and febrile infectious disease caused by the Gram-negative α-proteobacterium Orientia tsutsugamushi from the family Rickettsiaceae that is widely distributed in Northern, Southern and Eastern Asia. In the present study, we analysed the serum proteome of scrub typhus patients to investigate specific clinical protein patterns in an attempt to explain pathophysiology and discover potential biomarkers of infection. Methods Serum samples were collected from three patients (before and after treatment with antibiotics) and three healthy subjects. One-dimensional sodium dodecyl sulphate–polyacrylamide gel electrophoresis followed by liquid chromatography-tandem mass spectrometry was performed to identify differentially abundant proteins using quantitative proteomic approaches. Bioinformatic analysis was then performed using Ingenuity Pathway Analysis. Results Proteomic analysis identified 236 serum proteins, of which 32 were differentially expressed in normal subjects, naive scrub typhus patients and patients treated with antibiotics. Comparative bioinformatic analysis of the identified proteins revealed up-regulation of proteins involved in immune responses, especially complement system, following infection with O. tsutsugamushi, and normal expression was largely rescued by antibiotic treatment. Conclusions This is the first proteomic study of clinical serum samples from scrub typhus patients. Proteomic analysis identified changes in protein expression upon infection with O. tsutsugamushi and following antibiotic treatment. Our results provide valuable information for further investigation of scrub typhus therapy and diagnosis. Electronic supplementary material The online version of this article (10.1186/s12014-018-9181-5) contains supplementary material, which is available to authorized users.

The nocturnal enuresis is challenging due to the increased social activities of the children. This disorder significantly bothers both the children and their parents in psychological, behavioral, social, and financial manners. However, the primary treatments have limitations and further are not able to completely cure the disorder. In order to reduce pain and burdens of patients and their parents, it is important to accurately estimate when the enuretic incident occurs in advance. For the estimation, we have comprehensively investigated various studies of the nocturnal enuresis in the diverse fields. Through the investigations, we have summarized four hypotheses of the physiological signals related to the enuretic moment. In order to conquer the nocturnal enuresis, we design a preliminary framework sensing and investigating the physiological signals with the sensors. Our synthesized approach to understand and estimate the moments of the enuretic incidents can establish a foothold to complete the promising prediction system.

The Disc Agarose Channel (DAC) system utilizes microfluidics and imaging technologies and is fully automated and capable of tracking single cell growth to produce Mycobacterium tuberculosis (MTB) drug susceptibility testing (DST) results within 3~7 days. In particular, this system can be easily used to perform DSTs without the fastidious preparation of the inoculum of MTB cells. Inoculum effect is one of the major problems that causes DST errors. The DAC system was not influenced by the inoculum effect and produced reliable DST results. In this system, the minimum inhibitory concentration (MIC) values of the first-line drugs were consistent regardless of inoculum sizes ranging from ~103 to ~108 CFU/mL. The consistent MIC results enabled us to determine the critical concentrations for 12 anti-tuberculosis drugs. Based on the determined critical concentrations, further DSTs were performed with 254 MTB clinical isolates without measuring an inoculum size. There were high agreement rates (96.3%) between the DAC system and the absolute concentration method using Löwenstein-Jensen medium. According to these results, the DAC system is the first DST system that is not affected by the inoculum effect. It can thus increase reliability and convenience for DST of MTB. We expect that this system will be a potential substitute for conventional DST systems.

Two hydrodynamic features of phonon transport, phonon drift and second sound, in a (20,20) single-wall carbon nanotube (SWCNT) are discussed using lattice dynamics calculations employing an optimized Tersoff potential for atomic interactions. We formally derive a formula for the contribution of drift motion of phonons to total heat flux at steady state. It is found that the drift motion of phonons carries more than $70%$ and $90%$ of heat at 300 and 100 K, respectively, indicating that phonon flow can be reasonably approximated as hydrodynamic if the SWCNT is long enough to avoid ballistic phonon transport. The dispersion relation of second sound is derived from the Peierls-Boltzmann transport equation with Callaway's scattering model and quantifies the speed of second sound and its relaxation. The speed of second sound is around 4000 m/s in a (20,20) SWCNT and the second sound can propagate more than 10 \textmu{}m in an isotopically pure (20,20) SWCNT for frequency around 1 GHz at 100 K.

We discuss the use of planar Hall effect (PHE) in a ferromagnetic GaMnAs film with two in-plane easy axes as a means for achieving novel logic functionalities. We show that the switching of magnetization between the easy axes in a GaMnAs film depends strongly on the magnitude of the current flowing through the film due to thermal effects that modify its magnetic anisotropy. Planar Hall resistance in a GaMnAs film with two in-plane easy axes shows well-defined maxima and minima that can serve as two binary logic states. By choosing appropriate magnitudes of the input current for the GaMnAs Hall device, magnetic logic functions can then be achieved. Specifically, non-volatile logic functionalities such as AND, OR, NAND, and NOR gates can be obtained in such a device by selecting appropriate initial conditions. These results, involving a simple PHE device, hold promise for realizing programmable logic elements in magnetic electronics.

We have systematically investigated the influence of annealing on the magnetic anisotropy properties of GaMnAs film using an epilayer with a Mn concentration of 6.2%. The GaMnAs epilayer was grown by molecular beam epitaxy and the planar Hall effect measurement was used to monitor the magnetic anisotropy of the film. We found significant annealing-induced changes in the magnetic anisotropy properties of the GaMnAs film that depended on the annealing conditions. For example, the cubic anisotropy that gave a four-fold symmetry of magnetic easy axes decreased while the uniaxial anisotropy that gave a two-fold symmetry of magnetic easy axes increases in the samples annealed temperature below 300 °C. In particular, the uniaxial anisotropy along the [010] direction in as-grown GaMnAs film changed to the [100] direction by rotating by 90° after the sample was annealed at 300 °C for 3 h. This investigation thus indicates that the magnitude and the direction of the magnetic anisotropy in the GaMnAs film can be effectively controlled by choosing an appropriate annealing time and temperature.

The effect of buffer layer on the magnetic anisotropy of Fe film has been investigated by using the planar Hall effect measurement. The Fe films were grown on four different buffer layers, such as GaAs, ZnSe, ZnTe, and Ge, by molecular beam epitaxy. The field and angle dependent planar Hall effect measurements revealed the presence of two types of magnetic anisotropies, i.e., cubic crystalline anisotropy along the 〈100〉 directions and uniaxial anisotropy along the 〈110〉 crystallographic directions, in all four Fe films investigated in the study. However, the relative strength of the two types of anisotropies varies significantly depending on the type of buffer layer. Specially, in the Fe film grown on the Ge buffer layer, the uniaxial anisotropy almost disappeared and the entire magnetic anisotropy was dominated by cubic anisotropy with a four-fold symmetry. This suggests that the growth of Fe film on the Ge surface is different from its growth on other surfaces such as GaAs, ZnSe, and ZnTe buffers, where the asymmetric reconstruction process of anions (i.e., As, Se, or Te) is present at the surface.

Epidermal growth factor receptor (EGFR) has been recognized as an important prognostic marker expressed in cancer cells because its activation is associated with key features of cancer including tumor growth, survival, angiogenesis, and metastasis. Cetuximab is the first monoclonal antibody drug that targets EGFR overexpressed in cancer cells. It easily binds to EGFR, thereby down-regulating the receptor, blocking EGFR-mediated tyrosine kinase activity, and inhibiting cellular proliferation. Thus, EGFR–cetuximab binding can be quantified to monitor receptor status and the prognosis of cancer therapy. In this work, we report using SERS imaging to assess the inhibitory effect of cetuximab on EGFR expressed on cancer cells. From SERS mapping images using silica-encapsulated gold nanotags, the localized spatial distribution of EGFR that was not inhibited by cetuximab could be determined. Furthermore, EGFR expression could be accurately quantified through the statistical analysis of surface-enhanced Raman scattering (SERS) spectral data. Our experimental data demonstrate the feasibility of SERS imaging to improve the prognostic efficacy of cetuximab treatment.

The effect of light illumination on the magnetic anisotropy of GaMnAs has been investigated by using the planar Hall effect measurement. In as-grown GaMnAs, typical types of magnetic anisotropies, cubic crystalline anisotropy along the 〈100〉 directions and uniaxial anisotropy along the [110] direction, were clearly observed in the planar Hall resistance (PHR) measurements. The behavior of the PHR, however, changed after light illumination by showing significant asymmetry between the [100] and the [010] directions, which was explained by the appearance (or enhancement) of a new type of uniaxial anisotropy along the [100] direction in the film. The experiment reveals that light illumination can significantly alter the magnetic anisotropies of the GaMnAs film by changing the magnitude of existing anisotropies as well as inducing anisotropy along the [100] direction.

The effect of annealing on the magnetic anisotropy of a GaMnAs film with a low Mn composition of 2% has been investigated. Hall measurements have been performed with an external field applied in- and out-of-plane. In as-grown samples, the behavior of the Hall resistance indicates that the out-of-plane magnetic anisotropy dominates over the in-plane anisotropy. The vertical anisotropy, however, gradually decreased with increasing annealing temperatures and changed to in-plane dominant anisotropy in the film annealed at 300 °C. Furthermore, it was found that the direction of the uniaxial anisotropy in the domain with the in-plane easy axes, changed from the [110] direction in as-grown film to the [ 1 1 ¯ 0 ] direction in the annealed film. This revealed that annealing altered the magnetic anisotropy of the GaMnAs film between out-of-plane and in-plane directions as well as within the film plane.

We report a highly sensitive detection method for anti-CCP autoantibodies using a SERS-based magnetic immunosensor. The proposed immunoassay technique is expected to be a new clinical tool for the early diagnosis of rheumatoid arthritis (RA).

Magnetic anisotropy of the ferromagnetic semiconductor GaMnAs film grown on a (0 0 1) GaAs substrate was investigated by using Hall effect and magnetization measurements. When field strength was swept at a fixed direction in the film plane, abrupt transitions in the Hall resistance appeared while reducing the field strength even before the field direction is reversed. We show that this phenomenon is related to the presence of magnetic domains with a vertical easy axis in the film, as identified via Hall measurements performed with a field applied normal to the plane. The coexistence of magnetic domains with both in-pane and out-of-plane anisotropies in a single film was further confirmed by direct measurement of the corresponding magnetization components of the film.

NELL2 was first identified as a mammalian homolog of the chicken NEL protein. It was expressed in neurons and has been suggested to play a role in cell survival. However, no clear evidence has yet been available for functions of NELL2. In this study, we found two E2F1 binding sites located in the NELL2 promoter region. We examined the expression of NELL2 and E2F1 in human breast cancer cells (MDA-MB231, MCF7) and bladder cancer cells (5637, UC5). In MDA-MB231 and 5637, the expression levels of NELL2 and E2F1 were higher. To examine the interaction between E2F1 and NELL2, the binding activity was checked by a promoter assay and chromatin immunoprecipitation. From the results, we suggest that NELL2 is a novel target gene of E2F1, which is a key regulator of cell proliferation. We reveal that expression of NELL2 is regulated by E2F1, specifically, mRNA and protein levels of NELL2 are elevated upon activation of exogenous E2F1. Moreover, cells overexpressing NELL2 increased their invasive ability and an enhan...

We carried out systematic planar Hall effect (PHE) measurements on a layer of GaMnAs grown on a Si substrate. The field scans of the planar Hall resistance (PHR) data obtained at 4 K show a transition behavior, which is similar to the magnetization reorientation process often observed in GaMnAs film grown on a GaAs substrate that has both anisotropies along the and the directions. The dependence of the PHR on the applied field direction revealed the presence of an asymmetry between the and the directions in the magnetic energy of the film. The directions of the magnetic easy axes determined by the PHR value at zero field were about 9° away from the directions. The PHR further shows the absence of the difference in the anisotropy between the directions, indicating no preference of magnetic anisotropy for either the [110] or the [ 1 ¯ 10 ] direction in the GaMnAs grown on a Si substrate.

The magnetic anisotropy properties of GaMnAs ferromagnetic films have been investigated by using planar Hall effect measurements. The field scan of the planar Hall resistance (PHR) showed a two-step switching behavior indicating a strong cubic anisotropy along the 〈100〉 directions. The difference in the behaviors of the PHR for two applied field directions, $$\left[ {1\bar 10} \right]$$ and [110], was understood via the well-known uniaxial anisotropy along the [110] direction. In addition to such known effects, we also found the presence of an asymmetry for the [010] and the [100] directions. This new asymmetry phenomenon was explained by introducing an additional uniaxial anisotropy field H u2 along the [100] and the $$\left[ {\bar 100} \right]$$ directions, which coincide with the two directions of cubic anisotropy. The values of the anisotropy fields, cubic (H c ), first uniaxial (H u1), and second uniaxial (H u2), were obtained by analyzing the angle dependence of the PHR. Although the value of H u2 is small, its effect is clearly observed at high temperatures above 25 K, where the transition of the magnetization occurred before the field direction had been reversed during the magnetization reversal process.

A novel SERS-based sandwich immunoassay using DNA aptamers, silica-encapsulated hollow gold nanospheres (SEHGNs) and a gold-patterned microarray was developed for sensitive detection of VEGF (vascular endothelial growth factor) angiogenesis protein markers. Here, a DNA aptamer conjugated to SEHGN was used as a highly reproducible SERS-encoding nanoprobe, and a hybrid microarray including hydrophilic gold wells and other hydrophobic areas was used as a SERS substrate. Target specific DNA aptamers that fold into a G-quadruplex structure were used as a target recognition unit instead of VEGF antibodies. The detection sensitivity was increased by 2 or 3 orders of magnitude over the conventional ELISA method. In particular, the dynamic concentration range was 3 or 4 orders of magnitude greater than that of conventional ELISA. The results demonstrate that this sensing strategy using DNA aptamers is a powerful platform for the design of novel immune-sensors with high performance. In particular, SERS-based detection using SEHGNs provides great promise for highly sensitive biomarker sensing with unprecedented advantages.

Bismuth telluride (Bi2Te3) and its alloys have been widely investigated as thermoelectric materials for cooling applications at around room temperature. We report a systematic study on many compounds in the Bi2Te3–Bi2Se3–Bi2S3 system. All the samples were fabricated by high energy ball milling followed by hot pressing. Among the investigated compounds, Bi2Te2S1 shows a peak ZT ∼0.8 at 300 °C and Bi2Se1S2 ∼0.8 at 500 °C. The results show that these compounds can be used for mid-temperature power generation applications. The leg efficiency of thermoelectric conversion for segmented elements based on these n-type materials could potentially reach 12.5% with a cold side at 25 °C and a hot side at 500 °C if appropriate p-type legs are paired, which could compete well with the state-of-the-art n-type materials within the same temperature range, including lead tellurides, lead selenides, lead sulfides, filled-skutterudites, and half Heuslers.

Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) has high electrical conductivity (∼10³ S cm⁻¹) but it exhibits a low Seebeck coefficient (

We suggest a method of inspecting the latent space of stock market data using genetic programming. Given black box patterns and (stock, day) tuples a relation matrix is constructed. Applying a low-rank matrix factorization technique to the relation matrix induces a latent vector space. By manipulating the latent vector representations of black box patterns, the geometry of the latent space can be examined. Genetic programming constructs a tree representation corresponding to an arbitrary latent vector representation, allowing us to interpret the result of the inspection.

Chart pattern analysis uses knowledge extracted from graphical information of price movements. There are two representative types of problems in chart pattern analysis: the matching problem and the search problem. There have been extensive studies on chart pattern matching. However, chart pattern search has not yet drawn much interest. Instead of automatic search, most studies use chart patterns manually designed by financial experts. In this paper, we suggest an automatic algorithm that searches a rule-based chart pattern. We formulate rule-based chart pattern search as an optimization problem for a genetic algorithm. The suggested genetic algorithm includes a considerable amount of problem-specific manipulation. The algorithm successfully found attractive patterns working on the Korean stock market. We studied the rules used in the found patterns, noting that they are rising-support patterns. In addition, the automated pattern generation uses designs at a higher level of abstraction.

A novel surface-enhanced Raman scattering (SERS)-based lateral flow immunoassay (LFA) biosensor was developed to resolve problems associated with conventional LFA strips (e.g., limits in quantitative analysis and low sensitivity). In our SERS-based biosensor, Raman reporter-labeled hollow gold nanospheres (HGNs) were used as SERS detection probes instead of gold nanoparticles. With the proposed SERS-based LFA strip, the presence of a target antigen can be identified through a colour change in the test zone. Furthermore, highly sensitive quantitative evaluation is possible by measuring SERS signals from the test zone. To verify the feasibility of the SERS-based LFA strip platform, an immunoassay of staphylococcal enterotoxin B (SEB) was performed as a model reaction. The limit of detection (LOD) for SEB, as determined with the SERS-based LFA strip, was estimated to be 0.001 ng mL(-1). This value is approximately three orders of magnitude more sensitive than that achieved with the corresponding ELISA-based method. The proposed SERS-based LFA strip sensor shows significant potential for the rapid and sensitive detection of target markers in a simplified manner.

This paper proposes a low-phase-noise ring-VCO-based frequency multiplier with a new subharmonic direct injection locking technique that only uses a time-delay cell and four MOS transistors. Since the proposed technique behaves as an exclusive OR and can double the reference signal frequency, it increases phase correction points and achieves low phase noise characteristic across the wide output frequency range. The frequency multiplier was fabricated by using 65 nm Si CMOS process. Measured 1-MHz-offset phase noise at 6.34 GHz with reference signals of 528MHz was −119 dBc/Hz.

Two series of GaMnAs/GaAs superlattices (SSs) comprised of ferromagnetic semiconductor GaMnAs layers and non-magnetic GaAs spacers were investigated by the electronic transport measurements with an external magnetic field applied in the plane of the sample. The two SL series consisted of specimens that were structurally the same, but the GaAs spacers layers of one series were doped by Be, while in the second series the spacers were undoped. Although in field scans taken at 4 K all SLs showed a typical anisotropic magnetoresistance (MR) behavior dominated by magnetic anisotropy, similar to that normally observed in single GaMnAs ferromagnetic layers grown on GaAs (001) substrates, some of the SLs showed signatures of interaction between the GaMnAs layers in the form of broadening of the MR hysteresis. The effect of inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers became clear in the MR data taken at 30 K, where the strength of the magnetic anisotropy was reduced to the level of the inter-layer interaction. Specifically, MR measurements on two of the Be-doped SLs (BD2 and BD3) exhibited conspicuously large values of resistance at zero field, along with transitions of magnetization with negative coercive fields. The observation of these features in GaMnAs/GaAs SLs indicates the presence of spontaneous antiferromagnetic (AFM) inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers. The study further revealed that the IEC in the GaMnAs multilayers strongly depended on the properties of the non-magnetic GaAs spacers, such as their thickness and the density of carriers in the layers. Importantly, these IEC effects occurred on a longer range than that expected from current theoretical studies.

We report a highly sensitive surface-enhanced Raman scattering (SERS)-based immunoassay platform for the multiplex detection of biomarkers. For this purpose, a gold-patterned microarray chip has been fabricated and used as a SERS detection template. Here, a typical sandwich immunocomplex protocol was adopted. Monoclonal antibodies were immobilized on gold patterned substrates, and then antigen solutions and polyclonal antibody-conjugated hollow gold nanospheres (HGNs) were sequentially added for the formation of sandwich immunocomplexes. Antigen biomarkers can be quantitatively assayed by monitoring the intensity change of a characteristic SERS peak of a reporter molecule adsorbed on the surfaces of HGNs. Under optimized assay conditions, the limits of detections (LODs) were determined to be 10 fg/mL for human IgG and 10–100 fg/mL for rabbit IgG. In addition, the SERS-based immunoassay technique can be applied in a wider dynamic concentration range with a good sensitivity compared to ELISA. The proposed method fulfills the current needs of high sensitivity and selectivity which are essential for the clinical diagnosis of a disease.

Nopp140 is a highly phosphorylated protein that resides in the nucleolus of mammalian cell and is involved in the biogenesis of the nucleolus. It interacts with a variety of proteins related to the synthesis and assembly of the ribosome. It also can bind to a ubiquitous protein kinase CK2 that mediates cell growth and prevents apoptosis. We found that Nopp140 is an intrinsically unfolded protein (IUP) lacking stable secondary structures over its entire sequence of 709 residues. We discovered that mitoxantrone, an anticancer agent, was able to enhance the interaction between Nopp140 and CK2 and maintain suppressed activity of CK2. Surface plasma resonance studies on different domains of Nopp140 show that the C-terminal region of Nopp140 is responsible for binding with mitoxantrone. Our results present an interesting example where a small chemical compound binds to an intrinsically unfolded protein (IUP) and enhances protein-protein interactions.

We report a highly sensitive optical imaging technology using surface-enhanced Raman scattering (SERS)-fluorescence dual modal nanoprobes (DMNPs). Fluorescence microscopy is a well-known imaging technique that shows specific protein distributions within cells. However, most currently available fluorescent organic dyes have relatively weak emission intensities and are rapidly photo-bleached. Thus more sensitive and stable probes are needed. In this work we develop DMNPs, which can be used for both SERS and fluorescence detection. SERS detection is a powerful technique that allows ultrasensitive chemical or biochemical analysis through unlimited multiplexing and single molecule sensitivity. Combining advantages of fluorescence and SERS allows these dual modal nanostructures to be used as powerful probes for novel biomedical imaging. In this work, the fabrication and characterization of the SERS-fluorescence DMNPs and application to biological imaging were investigated using markers CD24 and CD44, which are co-expressed in MDA-MB-231 breast cancer cells, as a model system. SERS imaging with DMNPs was found to be a powerful tool to determine the co-localization of CD24 and CD44 in the cell.

The use of silica shells offers many advantages in surface-enhanced Raman scattering (SERS)-based biological sensing applications due to their optical transparency, remarkable stability in environmental media, and improved biocompatibility. Here, we report a novel layer-by-layer method for the preparation of silica-hollow gold nanosphere (HGN) SERS tags. Poly(acrylic acid) was used to stabilize Raman reporter-tagged HGNs prior to the adsorption of a coupling agent, after which a silica shell was deposited onto the particle surface using Stöber's method. Importantly, competitive adsorption of the Raman reporter molecules and coupling agents, which results in unbalanced loading of reporter molecules on individual nanoparticles, was avoided using this method. As a result, the loading density of reporter molecules could be maximized. In addition, HGNs exhibited strong enhancement effects from the individual particles because of their ability to localize the surface electromagnetic fields through pinholes in the hollow particle structures. The proposed layer-by-layer silica-encapsulated HGN tags showed strong SERS signals as well as excellent multiplexing capabilities.

Systematic planar Hall measurements have been performed on a ferromagnetic Fe film grown on a standard (001) GaAs substrate at room temperature. The angular dependence of the planar Hall effect revealed the presence of both four-fold (cubic) and two-fold (uniaxial) anisotropies in the 7 nm thick Fe film. The dominance of the four-fold symmetric anisotropy, however, provided four magnetic easy axes near the (100) direction, which results in a two step switching phenomenon in the magnetization reversal process. An interesting asymmetric hysteresis loop was observed in the planar Hall resistance (PHR) when the turning point of the field scan is set at the value in the region of the second transition. The intermediate resistance states appearing in the asymmetric PHR loop were understood in terms of mutli-domain structures formed during the second switching of magnetization. Such multi-domain structure of the Fe film showing robust time stability provided additional Hall resistance states, which can be used for multi-valued memory device applications.