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The navigable percutaneous disc decompression (PDD) device L'DISQ is an effective and safe option for the treatment of lumbar discogenic pain. However, few studies have evaluated the prognostic factors of successful PDD using this device.This study aimed to evaluate the prognostic factors associated with the successful outcome of PDD using the L'DISQ for treating lumbar discogenic pain by following up patients before and one, 2, 3, and 6 months after the procedure.Retrospective cohort study.Tertiary university hospital.A successful outcome was defined as a= 50% reduction in the numeric rating scale scores for pain and a= 40% reduction in the Oswestry Disability Index scores at 6 months after the procedure. Clinical parameters and patient demographics, including pain duration, history of surgery, number of treatment levels, and the radiographic findings of lumbar magnetic resonance imaging (MRI), were also examined.Of the 106 patients included, 80 (75.5%) had successful outcomes at 6 months. Multivariable logistic regression analysis revealed that the presence of high-intensity zones (HIZs) (P = 0.016) was an independent positive predictor of successful PDD outcomes; conversely, migration of the herniated disc (P = 0.017) and bilaterally herniated discs (P = 0.001) were negative predictors.The limitations of this study were its retrospective design, absence of a control group, and difficulty in predicting the effect when multiple levels were involved because of the use of MRI characteristics of the disc as a predictor.The presence of HIZs, the absence of migration of herniated discs, and the presence of unilaterally herniated discs are positive predictors of successful outcomes of PDD using the L'DISQ.

Incidences of brain death due to nicotine overdose by e-cigarettes have been increasing. In such cases, liver donation has been not reported because of the secondary damage to the liver due to metabolism of large amounts of nicotine. However, kidneys have been considered acceptable for transplant. Here, we present a successful case of liver transplant from a brain-dead donor due to intentional nicotine ingestion who did not have extensive steatosis. To the best of our knowledge, this is the first report of such a case.

In this paper, a generalized switching modification method is proposed to reduce the root-mean-square (rms) current flowing into a dc-link capacitor in a dc–dc–ac structure consisting of a boost converter and a three-phase inverter. To analyze the current flowing into the capacitor, we analyze the currents at the respective converter and inverter sides. Based on this analysis, we derive an analytical method to find the modification time between the converter and inverter pulsewidth modulation (PWM) carriers through a Fourier series and approximation to facilitate real-time implementation. Real-time implementation of the modification time calculated by the derived method is described. To verify the validity of the proposed method, experimental results are presented based on a 1-kVA dc–dc–ac prototype. The proposed method has a better capacitor rms current reduction performance than the conventional method in various inverter power factors and PWM strategies. Especially, it has an excellent performance in mid-power factor level (0.95–0.1).

2'-Fucosyllactose (2-FL), one of the most abundant oligosaccharides in human milk, has been spotlighted for its neutraceutical and pharmaceutical potentials. Microbial production of 2-FL is promising since it is efficient as compared to other production methods. In 2-FL microbial production via the salvage pathway for biosynthesis of guanosine 5'-diphosphate (GDP)-l-fucose from fucose, the conversion yield from fucose is important because of the high price of fucose. In this study, deletion of the genes (araA and rhaA) coding for arabinose isomerase (AraA) and rhamnose isomerase (RhaA) was attempted in engineered Escherichia coli for improving 2-FL production by using fucose, lactose, and glycerol. The engineered E. coli constructed previously is able to express fucokinase/GDP-l-fucose pyrophosphorylase (Fkp) from Bacteroides fragilis and the α-1,2-fucosyltransferase (FucT2) from Helicobacter pylori and deficient in β-galactosidase (LacZ), fucose isomerase (FucI), and fuculose kinase (FucK). The additional double-deletion of the araA and rhaA genes in the engineered E. coli enhanced the product yield of 2-FL to 0.52 mole 2-FL/mole fucose, and hence the concentration of 2-FL reached to 47.0 g/L, which are 44% and two-fold higher than those (23.1 g/L and 0.36 mole 2-FL/mole fucose) of the control strain in fed-batch fermentation. Elimination of sugar isomerases exhibiting promiscuous activities with fucose might be critical in the microbial production of 2-FL through the salvage pathway of GDP-l-fucose.

This paper demonstrates wavelength reused bidirectional transmission for a reflective coherent passive optical network (R-Co-PON). By reusing the downstream optical signal as the upstream optical carrier, the proposed R-Co-PON enhances the optical spectral efficiency. In an experimental demonstration, the proposed R-Co-PON achieved a symmetrical bidirectional transmission rate of 12 Gb/s using a 73-km-long fiber loopback architecture. The experiments confirmed the potential applicability of the proposed system in future optical access networks, particularly those using wavelength-division multiplexing.

Monolayer doping (MLD) has been regarded as the most suitable doping method for future semiconductor devices. MLD based on surface functionalization can be seriously affected by the surface states, including the orientations, crystallinities, and defects. We report for the first time the effect of surface states on boron-MLD (B-MLD) process and discuss the applicability of MLD for a fin structures. Depending on the surface states, the monolayer formation reaction is restricted, which causes more than five-fold differences in the doping level. Therefore, the surface states should be gravely considered before applying MLD and are crucial constraints in the MLD process on non-planar structures that have different surface states depending on its structural position. The B-MLD process on as-cleaned (100) and (110) silicon surfaces provides doping levels of 4.69 × 1020 and 2.48 × 1020 atoms/cm3, respectively. The MLD efficiency on the (110) orientation is degraded by insufficient reaction sites for the hydrosilylation reaction on the monohydride-terminated (110) silicon surface. Additionally, the surface damage interrupts the formation of a dopant-containing monolayer, causing a poor doping level and dose uniformity. Our research provides new insights into the development of wet-chemical doping methods for non-planar devices by studying the effect of surface states on MLD efficiency.

Photo-thermal processing assisted by laser irradiation is proposed as a novel method to control the phase of nickel silicide with reduction in the diffusion of nickel into the silicon substrate. The third harmonics of Nd3+:Y3Al5O12 laser (wavelength, 355 nm) is used for photo-thermal processing. Optical and thermal simulations are performed to obtain an optimum thickness (30 nm) of the nickel film for photo-thermal processing and to predict the temperature profile of the nickel-silicon interface during laser irradiation. It is confirmed that Ni2Si, NiSi and NiSi2 phase are effectively formed at the laser energy densities of 15, 20–40, and 50 mJ/cm2, respectively. We demonstrate that the phases of nickel silicide determined by Raman spectroscopy and X-ray diffraction analyses are in good agreement with those predicted by the heat transfer simulation. In addition, undesirable diffusion of nickel into silicon substrate is considerably reduced by instantaneous photo-thermal processing using the nano-second laser (pulse duration, 6 ns).

Channel equalization and phase noise compensation are required in coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission systems for reliable performance. In general, redundant data such as training symbols and pilot tones are necessary for channel and phase noise estimation in quadrature amplitude modulation (QAM) based CO-OFDM systems, which reduces the spectral efficiency of the system. Especially, in the coherent passive optical network (PON), the redundancy increases as the number of subscribers increases. In this letter, we propose a differential amplitude shift keying (DAPSK)-based CO-OFDM transmission for PON system, which does not require channel equalization and phase noise compensation processes. The proposed DAPSK-based CO-OFDM transmission was experimentally demonstrated, and the performance according to receiver launched power and the number of subcarriers was compared with QAM-based CO-OFDM.

In this paper, thermal stability of a one-dimensional metallodielectric photonic crystal (1D MDPhC) structure based on W and SiO2 for thermophotovoltaic systems is reported. The thermal degradation mechanism of the structure, in its operating temperature range, is thoroughly investigated by using energy dispersive spectroscopy (EDS) with transmission electron microscope (TEM) and depth-profiling X-ray photoelectron spectroscopy (XPS). It is found that the structure is entirely destroyed under 1400 K by an inter-diffusion process forming a mixture of W and SiO2 without measurable oxidization of W. But, long-term annealing results in oxidization of W layer even at a lower temperature of 1300 K. During the long-term annealing, oxygen atoms in outside atmosphere are believed to cause oxidation of the upper W layer below the top SiO2 layer. Additionally, delaminated spots are observed over the surface. These thermal behaviors are potential clues to prevent or minimize thermal degradation of the multilayer structure under high temperature operation.

2'-Fucosyllactose (2-FL) is one of most abundant oligosaccharides in human milk, which is involved in many biological functions for infant health. Since 2-FL has a great potential in application to functional food materials and pharmaceuticals, several microbial systems for mass production of 2-FL have been developed in recent years. Microbial production of 2-FL was suggested to be influenced by a number of factors including fucosylation activity of α-1,2-fucosyltransferase. In the present study, the wcfB gene coding for α-1,2-fucosyltransferase from Bacteroides fragilis was screened from eleven candidates of putative α-1,2-fucosyltransferase. Introduction of the wcfB gene allows the lacZ-deleted strain of E. coli expressing the genes for guanosine 5'-diphosphate (GDP)-l-fucose biosynthetic enzymes to produce 2-FL. As a result of fed-batch fermentation, 15.4g/L extracellular concentration of 2-FL with 2-FL yield of 0.858g/g lactose and productivity of 0.530g/L/h were obtained. In addition, the feasibility of industrial production of 2-FL using this microbial system was demonstrated by performing fed-batch fermentation in a 75L bioreactor.

We investigate the effect of the number of laser pulses on the formation of p+/n silicon ultra-shallow junctions during non-melt ultra-violet laser (wavelength, 355 nm) annealing. Through surface peak temperature calculating by COMSOL Multiphysics, the non-melt laser thermal annealing is performed under the energy density of 130 mJ/cm2. We demonstrate that increasing the number of laser pulses without additional pre-annealing is an effective annealing method for achieving good electrical properties and shallow junction depth by analyzing sheet resistance and junction depth profiles. The optimal number of laser pulses is eight for achieving a high degree of activation of dopant without further increase of junction depth. We have also explained the improved electrical characteristics of the samples on the basis of fully recovered crystallinity as revealed by Raman spectroscopy. Thus, it is suggested that controlling the number of laser pulses with moderate energy density is a promising laser annealing method without additional pre-annealing.

Optical interference noise (OIN), including optical beating interference and Rayleigh back-scattering noise, severely degrades transmission performance in self-coherent reflective passive optical network uplink transmission systems. A simple, cost-effective, and optical interferometry-based optical carrier cancelation method is proposed to reduce OIN. In this experiment, we demonstrate the cancelation of optical carriers, which is a major cause of OIN, up to 29 dB. Under the conditions of higher fiber input power and longer transmission distance, a remarkable improvement in transmission performance in terms of the eye-pattern and bit-error-rate was achieved.

We propose and demonstrate a novel all-optical virtual private network (VPN) using a microwave photonic filter, which enables inter-communications among optical network units in a passive optical network system. In our scheme, an optical coupler based recirculating delay line is used at optical line terminal as an optical subsystem to implement a microwave photonic-bandpass filter (MP-BPF). The periodic passbands of an MP-BPF are used to transmit VPN signal, whereas stopbands are used for conventional upstream transmission. The proposed system has two critical issues, optical phase-induced intensity noise in the MP-BPF and Rayleigh back-scattering interference by a single-fiber loop back link. To overcome the issues, an RF clipping tone based spectrum-broadening technique is applied to uplink transmitter. The proposed all-optical VPN system is tolerant to wavelength of VPN optical carrier, and enables multi-VPN data transmission using multi-passbands of MP-BPF.

Phase diversity of coherent optical communication provides spectrally efficient higher-order modulation for optical communications. However, in-phase/quadrature (IQ) imbalance in coherent optical communication degrades transmission performance by introducing unwanted signal distortions. In a coherent optical orthogonal frequency division multiple access (OFDMA) passive optical network (PON), IQ imbalance-induced signal distortions degrade transmission performance by interferences of mirror subcarriers, inter-symbol interference (ISI), and inter-channel interference (ICI). We propose parallel-channel discrete multitone (DMT) transmission to mitigate transceiver IQ imbalance-induced signal distortions in coherent orthogonal frequency division multiplexing (OFDM) transmissions. We experimentally demonstrate the effectiveness of parallel-channel DMT transmission compared with that of OFDM transmission in the presence of IQ imbalance.

Emissivity-tunable metamaterials of layered refractory metal and dielectric have great potentials as a simple thermophotovoltaic (TPV) selective emitter due to its near-omnidirectional, polarization-independent, and broadband selective emissivity. However, it is known that the stability of the layered structure is limited by the oxidation of metals. While there still exists ambiguity concerning the main source of oxygen between adjacent oxide layers and external residual oxygen, most reports focus on the adjacent layers. In this report, thermal stability of a tungsten-based layered metamaterial is investigated under a high-vacuum environment with great care to reduce residual oxygen. The results show unprecedented thermal stability up to 1200 °C for 3 h without any measurable oxidation of metal. This implies that the interlayer diffusion of oxygen from adjacent oxide layers is not exclusively responsible for the oxidation of metal. At such a high temperature, the layered metamaterial theoretically yields a high convertible radiative power density of 3.04 W/cm2 with comparable spectral efficiency of 40.2%. Finally, after performing series of thermal tests under higher thermal loads, we propose a novel high-temperature degradation model for layered metamaterials, the stability of which is ultimately limited by the agglomeration of thin metal layers.

L-Fucose (6-deoxy-L-galactose) is a major constituent of glycans and glycolipids in mammals. Fucosylation of glycans can confer unique functional properties and may be an economical way to manufacture L-fucose. Research can extract L-fucose directly from brown algae, or by enzymatic hydrolysis of L-fucose-rich microbial exopolysaccharides. However, these L-fucose production methods are not economical or scalable for various applications. We engineered an Escherichia coli strain to produce L-fucose. Specifically, we modified the strain genome to eliminate endogenous L-fucose and lactose metabolism, produce 2'-fucosyllactose (2'-FL), and to liberate L-fucose from 2'-FL. This E. coli strain produced 16.7 g/L of L-fucose with productivity of 0.1 g·L-1 ·h-1 in a fed-batch fermentation. This study presents an efficient one-pot biosynthesis strategy to produce a monomeric form of L-fucose by microbial fermentation, making large-scale industrial production of L-fucose feasible.

3-Fucosyllactose (3-FL), one of the major oligosaccharides in human breast milk, is produced in engineered Escherichia coli. In order to search for a good α-1,3-fucosyltransferase, three bacterial α-1,3-fucosyltransferases are expressed in engineered E. coli deficient in β-galactosidase activity and expressing the essential enzymes for the production of guanosine 5'-diphosphate-l-fucose, the donor of fucose for 3-FL biosynthesis. Among the three enzymes tested, the fucT gene from Helicobacter pylori National Collection of Type Cultures 11637 gives the best 3-FL production in a simple batch fermentation process using glycerol as a carbon source and lactose as an acceptor. In order to use glucose as a carbon source, the chromosomal ptsG gene, considered the main regulator of the glucose repression mechanism, is disrupted. The resulting E. coli strain of ∆LP-YA+FT shows a much lower performance of 3-FL production (4.50 g L-1 ) than the ∆L-YA+FT strain grown in a glycerol medium (10.7 g L-1 ), suggesting that glycerol is a better carbon source than glucose. Finally, the engineered E. coli ∆LW-YA+FT expressing the essential genes for 3-FL production and blocking the colanic acid biosynthetic pathway (∆wcaJ) exhibits the highest concentration (11.5 g L-1 ), yield (0.39 mol mol-1 ), and productivity (0.22 g L-1 h) of 3-FL in glycerol-limited fed-batch fermentation.

We propose a novel technique for mitigating the optical-beat-induced multi-user-interference (MUI) between the upstream multiple access signals in an orthogonal frequency division multiple access (OFDMA) passive optical network (PON). To provide upstream multiple access on a single-wavelength orthogonal frequency division multiplexing optical access network, optical beating interference and polarization diverseness are critical issues that severely degrade system performance. By using the proposed total intensity aggregation with self-homodyne coherent detection, we experimentally demonstrated stable transmission performance by reducing MUI in OFDMA PON upstream multiple access transmission.

A self-homodyne coherent detection technique using gain-saturated SOA (GS-SOA) is proposed. In the proposed system, local oscillator (LO) for optical coherent detection is extracted from the optical signal which is sent from the transmitter using the fact that the modulated downlink data can be erased with SOA operation in saturation region. Therefore, carrier frequency offset noise does not occur because LO light which is extracted from the received optical signal has totally same wavelength with the optical signal. In order to operate SOA operates in deep saturation region, high optical input power is needed. The proposed scheme was experimentally demonstrated, and the feasibility was discussed with the experimental results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:561–565, 2016

We propose window shaping based inter-band interference suppression technique in multi-band orthogonal frequency division multiple access (MB-OFDMA) based passive optical network (PON) system. Conventional MB-OFDMA and raised-cosine (RC) windowed MB-OFDMA were compared in QPSK transmission and adaptive modulation scenario. The effect of OFDM clipping ratio is analyzed, which is used to mitigate peak to average power ratio (PAPR) problem at the transmitter. Also, the MB-OFDMA based multiple access performance is investigated according to the different roll-off factor of RC window in terms of error vector magnitude (EVM) and effective bit rate. Compared with the conventional MB-OFDMA which is rectangular windowed, the RC-windowed MB-OFDMA shows better performance by suppressed sidelobe which leads to IBI. The maximum effective bit rate of 10 Gbps was achieved for 20 km transmission scenario at optimum roll-off factor, while it was 9 Gbps in the conventional MB-OFDMA transmission.

Whole-cell biotransformation of fatty acids can be influenced by the activities of catalytic enzymes and by the efficiency of substrate transport into host cells. Here, we improved fatty acid hydration activity of the recombinant Escherichia coli expressing an oleate hydratase of Stenotrophomonas maltophilia by targeting the catalytic enzyme into the periplasm instead of the cytoplasm. Recombinant E. coli producing OhyA in the periplasm under guidance of the PelB signal sequence (E. coli OhyA_PP) exhibited significantly greater hydration activity with oleic acid and linoleic acid compared to a recombinant E. coli producing OhyA in the cytoplasm (E. coli OhyA_CS). For example, the oleate double bond hydration rate of E. coli OhyA_PP was >400 μmol/g dry cells/min (400 U/g dry cells), which is >10-fold higher than that of E. coli OhyA_CS. As the specific activities of the enzymes targeted into the cytoplasm and periplasm were comparable, we assumed that targeting OhyA into the periplasm could accelerate fatty acid transport to the catalytic enzymes by skipping the major mass transport barrier of the cytoplasmic membrane. Our results will contribute to the development of whole-cell biocatalysts for fatty acid biotransformation.

In this report, a selective interface laser annealing (SILA) process is applied to the atomic-layer-deposited Al2O3 film/p-type silicon interface using an Nd3+: YAG laser with a wave-length of 532 nm. The absorptivity of the laser wavelength confirms a full absorption of the laser power to the Al2O3/Si interface without any loss through the Al2O3 film, which results in a successful selective annealing of the interface. Compared with conventional forming gas annealing (FGA), the SILA is found to build a thinner SiO2 interface layer and lead to a less reduction of capacitance. It is also revealed that the laser-annealed sample exhibits a surface blister density of 31 counts/mm2 which is much lower than the value of 250 counts/mm2 obtained from FGA. The suppression of the surface blister is attributed to the much shorter processing time of lasing (

Fucosyllactoses (FLs), present in human breast milk, have been reported to benefit human health immensely. Especially, 3-fucosyllactose (3-FL) has numerous benefits associated with a healthy gut ecosystem. Metabolic engineering of microorganisms is thought to be currently the only option to provide an economically feasible route for large-scale production of 3-FL. However, engineering principles for α-1,3-fucosyltransferases (1,3-FTs) are not well-known, resulting in the lower productivity of 3-FL than that of 2'-fucosyllactose (2'-FL), although both 2'-FL and 3-FL follow a common pathway to produce GDP-L-fucose. The C-terminus of 1,3-FTs is composed of heptad repeats, responsible for dimerization of the enzymes, and a peripheral membrane anchoring region. It has long been thought that truncation of most heptad repeats, retaining just 1 or 2, helps the soluble expression of 1,3-FTs. However, whether the introduction of truncated version of 1,3-FTs enhances the production of 3-FL in a metabolically engineered strain, is yet to be tested. In this study, the effect of these structural components on the production of 3-FL in Escherichia coli was evaluated through systematic truncation and elongation of the C-terminal regions of three 1,3-FTs from Helicobacter pylori. Although these three 1,3-FTs contained heptad repeats and membrane-anchoring regions of varying lengths, they commonly exhibited an optimal performance when the number of heptad repeats was increased, and membrane-binding region was removed. The production of 3-FL could be increased 10-20-fold through this simple strategy.

A new technique, which can increase the data rate in optical orthogonal frequency division multiplexed access link, is proposed in this paper. An adaptive sampling based on a compressive sensing (CS) technique is implemented in order to save channel bandwidth. The CS tells us that all signals with high sparsity, which is sampled below the Nyquist/Shannon limit, can be reconstructed successively using sufficient measurement. In this paper, it is reported that the compression ratio of 40 % is observed within the error free optical transmission (FEC limit: BER of 10−3) in case of QPSK symbols. It means that its data rate can be increased by 1.7 times (from 1.56 to 2.3 Gbps) using the proposed technique without the use of optical and electrical devices with higher physical bandwidth.

Objective: Some studies have evaluated the prognostic indicators associated with acute paraquat (PQ) poisoning. In this study, we externally validated the Yamaguchi index, which showed a good prognostic relevance in predicting the outcome of PQ poisoning. Methods: A retrospective analysis of 297 patients was performed. The Yamaguchi index was calculated using the following equation: Eq1 = (K+ × HCO3−)/(Creatinine × 0.088)(mEq/L) against time from PQ ingestion ( T). The patients were divided into three groups: group A: Eq1 > 1500 − 399 × log T, group B: 930 − 399 × log T < Eq1 ≤ 1500 − 399 × log T, and group C: Eq1 ≤ 930 − 399 × log T). Results: The overall mortality rate was 65.3% (194 of 297). The mortality rates of the three groups stratified by the Yamaguchi index were 7.1% (2 of 28), 22.4% (15 of 67), and 87.6% (177 of 202). The area under the receiver–operating characteristic curve for predicting mortality from the external validation of the Yamaguchi index was 0.842 (95% confidence interval: 0.795–0.882). Conclusion: The Yamaguchi index is a reliable prognostic factor and could be helpful in predicting mortality due to PQ poisoning.

We propose a scalable support WDM-based orthogonal frequency division multiple access-passive optical network uplink transmission system using an injection-locked Fabry–Perot laser diode (IL-FP-LD). This system uses an injection-locking technique to enhance the usable bandwidth by making stable channel states. By properly controlling the IL-FP-LD operation, the number of optical network units (ONU) within a wavelength can be increased, which improves the optical bandwidth efficiency for the uplink transmission. The experimental results show an enhanced modulation bandwidth of 3.5 GHz. Compared with a conventional RSOA which has a modulation bandwidth of 1.5 GHz, our scheme improves the number of ONUs that can be accommodated within a wavelength more than two times. The total discrete multitone signal received from the ONUs, with QPSK mapping on the subcarriers was 6.77 Gbps over a 23-km standard single mode fiber transmission. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1727–1732, 2015

Orthogonal frequency-division multiplexing (OFDM) is susceptible to multiple access interference and synchronization errors due to sidelobes, which hinder the integration of various applications and multiple access in OFDM-based optical transmission. In this letter, an adaptively modulated optical filter bank multicarrier with offset quadrature amplitude modulation-based sidelobe suppression is proposed in a wired/wireless converged optical network. We experimentally verified both the improvements in signal performance and spectral efficiency compared with OFDM in a multisender-supported optical network after a 50-km transmission.

The authors have proposed and experimentally demonstrated a novel slow adaptive orthogonal frequency division multiple access (OFDMA)-based passive optical network (PON) uplink transmission scheme using a 1-GHz reflective semiconductor optical amplifier operating as an optical network unit (ONU) in combination with Rayleigh backscattering (RB) mitigation in a 20-km single fibre loopback link. This RB mitigation, which can dramatically stabilise the channel state information and enhance the total throughput so that the OFDMA-PON transmitters can operate in the slow adaptive concept and provides beyond 15-Gbit/s uplink transmission, is achieved by employing 10-MHz low-frequency dithering of an optical seed carrier cooperating with a gain-saturated semiconductor optical amplifier at an optical line terminal. In doing so, the proposed scheme could guarantee a 50% total throughput enhancement with a proof-of-concept multiple access scenario for two ONUs, compared to its counterpart that does not apply the RB mitigation technique.

A carrier-suppressed reflective coherent passive optical network (CS-R-CO-PON) for mitigating optical interference is presented. Using an external modulator, the optical carrier of the upstream signal was suppressed and unwanted optical interferences, including the carrier-induced optical beat interference and Rayleigh backscattering, were effectively mitigated. Through experimental verification, we demonstrated that the proposed CS-R-CO-PON with orthogonal frequency-division multiplexing (OFDM) has a tolerance to the optical interferences in the upstream transmission.

In orthogonal frequency division multiple access-passive optical network (OFDMA-PON) uplink transmission with a direct detection system, the optical beat interference (OBI) noise is a very critical issue in regard to channel performance degradation. We have proposed a novel technique to suppress the OBI noise in intensity modulation and direct detection OFDMA-PON links by using an optical spectrum broadening method using the RF-clipping tone to improve the SNR of the discrete multitone modulation (DMT) signal with OBI noise suppression. We also experimentally analyzed the dependency of the RF clipping tone on the OBI noise suppression and dither effect. The results show that the received DMT signal in the optical line terminal can achieve 3 Gb/s over a 23 km SSMF with a BER of 2.3×10−4. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2706–2711, 2014

A new technique, which reduces optical beat interference (OBI) noise in orthogonal frequency division multiple access-passive optical network (OFDMA-PON) links, is proposed. A self-homodyne balanced detection, which uses a single laser for the optical line terminal (OLT) as well as for the optical network unit (ONU), reduces OBI noise and also improves the signal to noise ratio (SNR) of the discrete multi-tone (DMT) signal. The proposed scheme is verified by transmitting quadrature phase shift keying (QPSK)-modulated DMT signal over a 20-km single mode fiber. The optical signal to noise ratio (OSNR), that is required for BER of 10−5, is reduced by 2 dB in the balanced detection compared with a single channel due to the cancellation of OBI noise in conjunction with the local laser.

Objective Suicide by organophosphate insecticide (OPI) poisoning is a major clinical concern (predominantly in developing countries), and 200 000 deaths occur annually worldwide. Red cell distribution width (RDW) has been used to predict outcome in several clinical conditions. Here, we aimed to investigate the relationship between the RDW and 30-day mortality during OPI poisoning. Methods This retrospective analysis was performed between January 2008 and July 2013 in patients admitted to the emergency department after OPI poisoning. A Kaplan-Meier 30-day survival curve was analyzed in patients stratified according to the optimal cut-off point of RDW defined using a receiver operating characteristic (ROC) curve. Multivariate Cox proportional hazards analyses were conducted to determine the independent prognostic factors for 30-day mortality. Results Among 102 patients, 21 died, yielding a mortality of 20.6%. Elevated RDW was significantly associated with early mortality in patients with OPI poisoning. Levels of RDW that exceeded 13.5% (hazard ratio, 2.64; 95% confidence interval [CI], 1.05-6.60) were associated with increased mortality in the multivariate analysis. The area under the ROC curve of RDW was 0.675 (95% CI, 0.522-0.829). Conclusions This study showed that RDW is an independent predictor of 30-day mortality in patients with OPI poisoning.

We have proposed baseband orthogonal frequency division multiplexing (OFDM) optical transmission technique using I/Q channel separation based on dual polarization with intensity modulation/direct detection (IM/DD). We experimentally verified performance of a proposed system in compare with intermediate frequency (IF)-upconverted OFDM system. In order to obtain better performance, adaptively modulated optical OFDM signal was used in this study. As a result, experimentally achieved maximum throughput after 50 km single mode fiber transmission was 28 Gbps with only using 4 GHz signal bandwidth. The proposed technique has relatively simple hardware structure and reduces computational complexity compared to other methods (IF upconversion or Hermitian symmetry) in IM/DD-based polarization multiplexed OFDM system.

In coherent superhigh speed optical transmission link, compensating the system impairments are critical issues. Among these issues, phase noise and carrier frequency offset are the most important impairments which interrupt the signal recovery. This paper suggests a algorithm of digital signal processing that compensates the phase noise and carrier frequency offset and verified its validity. The suggested digital signal processing algorithm has a lower computational complexity compared with the previous algorithms, so it can ease the burden of signal processing at the receiver to provide high speed optical transmission system. ※ 본 연구는 미래창조과학부가 지원한 2013년 정보통신·방송(ICT) 연구개발사업의 연구결과로 수행되었습니다. First Author : Broadband Transmission Network Lab, Department of Electrical and Electronic Engineering, Yonsei University, phjokokok@yonsei.ac.kr, 학생회원 ° Corresponding Author : Broadband Transmission Network Lab, Department of Electrical and Electronic Engineering, Yonsei University, skhan@yonsei.ac.kr, 종신회원 * Broadband Transmission Network Lab, Department of Electrical and Electronic Engineering, Yonsei University 논문번호:KICS2014-02-055, Received February 11, 2014; Revised April 28, 2014; Accepted April 29, 2014 I. 서 론 다양한 통신서비스의 발달에 따른 사용자들의 요구 를 충족하기 위하여 광통신에서는 데이터 전송량 향 상이 최근 화두가 되고 있다 . 그중 코히어런트 기반 의 통신방식에서는 100 Gb/s, 400 Gb/s를 넘어 1 Tb/s까지도 연구되고 있다 . 고속의 전송을 위한 고 차 변조방식을 사용할 경우 위상잡음과 주파수 오프 셋은 가장 중요한 성능 저해 요소이다. 레이저에서 생기는 위상잡음은 광원에서 생기는 불안정성에 의해 The Journal of Korea Information and Communications Society '14-05 Vol.39C No.05 414 그림 1. 전체 QPSK광통신시스템 구조 Fig. 1. Structure of QPSK Optical Communication System 발생하며 Wiener process 모델을 따르는데, 이 불안정 성은 광원의 선폭을 수 MHz까지 변화시키며 송신단 과 수신단의 레이저에서 모두 발생한다. 이와 함께 송수신 레이저의 중심 주파수의 차이로 인해 생기는 주파수 오프셋에 의하여 수신된 신호는 본래의 위상 정보를 제대로 검출하지 못하게 되어 전송 성능에 큰 감소를 일으킨다 . 또한 전송량 향상은 계속되고 있 어 위상잡음과 주파수 오프셋을 보상하는 하드웨어의 계산량이 증가되고 있고 이는 하드웨어의 부담을 가 중시킨다. 본 논문에서는 새로운 알고리즘으로 디지털 신호처리를 통해 위상 잡음과 주파수 오프셋을 보상 하는 방법을 제안하였고 이에 대한 성능을 시뮬레이 션을 통하여 검증하였다.

In this paper, we propose a novel fast adaptive approach that was applied to an OFDM-PON 20-km single fiber loopback transmission system to improve channel performance in term of stabilized BER below 2 × 10−3 and higher throughput beyond 10 Gb/s. The upstream transmission is performed through light source-seeded modulation using 1-GHz RSOA at the ONU. Experimental results indicated that the dynamic rate adaptation algorithm based on greedy Levin–Campello could be an effective solution to mitigate channel instability and data rate degradation caused by the Rayleigh back scattering effect and inefficient resource subcarrier allocation.

The laccase gene of Polyporus brumalis was genetically transformed to overexpress its laccase. The transformants exhibited increased laccase activity and effective decolorization of the dye Remazol Brilliant Blue R than the wild type. When the transformants were pretreated with wood chips from a red pine (softwood) and a tulip tree (hardwood) for 15 and 45 days, they showed higher lignin-degradation activity as well as higher wood-chip weight loss than the wild type. When the wood chips treated with the transformant were enzymatically saccharified, the highest sugar yields were found to be 32.5 % for the red pine wood and 29.5 % for the tulip tree wood, on the basis of the dried wood weights, which were 1.6-folds higher than those for the wild type. These results suggested that overexpression of the laccase gene from P. brumalis significantly contributed to the pretreatment of lignocellulose for increasing sugar yields.

We experimentally demonstrate the use of millimeter-wave signal generation by optical carrier suppression (OCS) method using single-drive Mach–Zehnder modulator as a light sources seed for 20 Gb/s WDM-OFDM-PON in 20-km single fiber loopback transmission based on cost-effective RSOA modulation. Practical discrete rate adaptive bit loading algorithm was employed in this colorless ONU system to maximize the achievable bit rate for an average bit error rate (BER) below 2 × 10 −3 .

Multi-band OFDMA PON with windowing technique is proposed for asynchronous multiple access. In the asynchronous multiple access system, frequency orthogonality is not maintained among OFDM bands, and it leads to inter-band interference arisen from OFDM sidelobe. To mitigate this effect, raised cosine window is applied to suppress the sidelobe. The proposed system is experimentally compared with conventional Multi-band OFDMA PON according to different roll-off factor of raised cosine window.

Orthogonal frequency division multiple access-based passive optical network (OFDMA-PON) is considered as a strong candidate for next-generation optical access network. In intensity modulation/direct detection system, OFDMA-PON downlink transmission is relatively stable, but critical issues exist in uplink multiple access. Because of different optical paths, optical beat interference (OBI) and timing offset effect are generated, which seriously disturb signal detection. We propose optical pulse division multiplexing-based OBI reduction. By considering both the spectrum broadening effect and the time domain near orthogonality, OBI could be reduced. We demonstrate that the spectral efficiency can be improved from 0.37 to 3.8 bit/s/Hz in 1-GHz signal bandwidth. (C) 2016 Optical Society of America

Methanol is a commonly used acyl acceptor for lipase-driven biodiesel production, but a high concentration of methanol is detrimental for lipase activity. To overcome this drawback, a simple fed-batch process was developed by optimization of the methanol feeding strategy and reaction conditions. For the feeding strategy, an equal volume of pure methanol was fed twice with specified time intervals into a reactor initially containing a 1:1 molar ratio of soybean oil to methanol in order to adjust the net molar ratio of the oil to methanol to 1:3. In contrast with the batch reaction, a higher agitation speed in the fed-batch process elevated the conversion yield of soybean oil to biodiesel. An agitation speed of 600 rpm and a reaction temperature of 70°C were chosen as the optimal environmental conditions. Residual lipase activities for the fed-batch operation at 40 ∼ 70°C and 600 rpm were 7.1 ± 1.4 times higher than that of the batch method at 40°C with the same agitation speed, indicating that methanol feeding can prevent significant deactivation of lipase. Finally, two times feeding methanol at 2 and 6 hr resulted in a biodiesel productivity of 10.7%/h and 94.9% final conversion yield under the optimal conditions.

This paper proposes a method to charge a lithium ion battery with an integrated compensator. Unlike the conventional charging method which uses separate voltage/current compensators based on a constant voltage-constant current charge profile, the proposed method uses a single compensator. The conventional method requires a complicated design process such as separate plant modeling for compensator design and the compensator tuning process in the frequency domain. Moreover, it has the disadvantage of a transient state between the mode change. However, the proposed method simplifies the complicated process and eliminates the transient response. The proposed compensator is applied to the LLC resonant converter and is designed to provide smooth and reliable performance during the entire charging process. In this paper, for the compensator design, the frequency domain models of the LLC resonant converter at the constant voltage and constant current charging mode are derived including the impedance model of the battery pack. Additionally, the worst condition of the compensator design during the entire charging process is considered. To demonstrate the effectiveness of the proposed method, the theoretical design procedure is presented in this paper, and it is verified through experimental results using a 300 W LLC converter and battery pack.

Obese women have an increased risk for post-menopausal breast cancer. The physiological mechanism by which obesity contributes to breast tumourigenesis is not understood. We previously showed that HCCR-1 oncogene contributes to breast tumourigenesis as a negative regulator of p53 and detection of HCCR-1 serological level was useful for the diagnosis of breast cancer(.) In this study, we found that the HCCR-1 level is elevated in breast cancer tissues and cell lines compared to normal breast tissues. We identified apolipoprotein E (ApoE) interacting with HCCR-1. Our data show that HCCR-1 inhibits anti-proliferative effect of ApoE, which was mediated by diminishing ApoE secretion of breast cancer cells. Finally, HCCR-1 induced the severe obesity in transgenic mice. Those obese mice showed severe hyperlipidaemia. In conclusion, our results suggest that HCCR-1 might play a role in the breast tumourigenesis while the overexpression of HCCR-1 induces the obesity probably by inhibiting the cholesterol-lowering effect of ApoE. Therefore, HCCR-1 seems to provide the molecular link between the obesity and the breast cancer risk.

Cerebrospinal fluid (CSF) may be of valuable for exploring protein markers for the diagnosis of Alzheimer's disease (AD). The prospect of early detection and treatment, to slow progression, holds hope for aging populations with increased average lifespan. The aim of the present study was to investigate candidate CSF biological markers in patients with mild cognitive impairment (MCI) and AD and compare them with age-matched normal control subjects. In this report, we applied proteomics approaches to analyze 60 CSF samples derived from patients with neurodegenerative diseases such as MCI and AD. We classified patients by three groups: normal controls without cognitive dysfunction, MCI and AD. The AD group was subdivided into three groups by clinical severity according to clinical dementia rating (CDR), a well known clinical scale for dementia. We demonstrated a gradual decrease or absent of plasma retinol-binding protein (RBP) and haptoglobin precursor allele 1 in CSF from patients with MCI and AD compared to the age-matched normal subjects. Moreover, expression levels of both RBP and haptoglobin precursor allele 1 were observed to be very high in age-matched normal subjects. In contrast, the RBP and haptoglobin precursor allele 1 were much decreased in the MCI group; those expressions were more weak or absent in AD group, and correlated with disease severity and progression. These findings suggest that the CSF levels of both RBP and haptoglobin precursor allele 1 may be candidate biomarkers for the progression of normal to MCI to AD.