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Background Amoxicillin (Amx) is one of the most important antibiotics for eradication of Helicobacter pylori ( H. pylori). Main determinants of genetically stable Amx resistance are mutations in the C-terminus of penicillin-binding protein 1A ( pbp1A). However, contribution of individual mutation remains unclear. Methods 77 Amx-resistant (AmxR) and 77 Amx-susceptible (AmxS) H. pylori strains were isolated from gastric tissues, and DNA sequencing was performed to compare C-terminus sequences of pbp1A gene between AmxR and AmxS strains. Natural transformation of these mutated genes into amoxicillin-susceptible strains was performed. Results Among many mutations in pbp1A, D479E ( OR: 37.4, 95% CI: 5.53-252.49, P < .001), and T593 mutation ( OR: 32.0, 95% CI: 4.04-252.86, P < .001) independently contributed to Amx resistance in H. pylori strains. In the transformation experiment, T593 mutations were identified in their transformants showing Amx resistance. However, PCR product of D479E was not inserted into recipient ( ATCC 43504) resulting in transformation failure. Conclusion Amx resistance is associated with various substitutions in pbp1A and T593 mutation contributes to Amx resistance of H. pylori. [ABSTRACT FROM AUTHOR]

The gastric accommodation reflex is an important mechanism in gastric physiology. However, the aging-associated structural and functional changes in gastric relaxation have not yet been established. Thus, we evaluated the molecular changes of interstitial cell of Cajal (ICC) and neuronal nitric oxide synthase (nNOS) and the function changes in the corpus of F344 rats at different ages (6-, 31-, 74-wk and 2-yr). The proportion of the c-Kit-positive area in the submucosal border (SMB) and myenteric plexus (MP) layer was significantly lower in the older rats, as indicated by immunohistochemistry. The density of the nNOS-positive immunoreactive area also decreased with age in the SMB, circular muscle (CM), and MP. Similarly, the percent of nNOS-positive neuronal cells per total neuronal cells and the proportion of nNOS immunoreactive area of MP also decreased in aged rats. In addition, the mRNA and protein expression of c-Kit and nNOS significantly decreased with age. Expression of stem cell factor (SCF) and the pan-neuronal marker PGP 9.5 mRNA was significantly lower in the older rats than in the younger rats. Barostat studies showed no difference depending on age. Instead, the change of volume was significantly decreased by L-NG63-nitroarginine methyl ester in the 2-yr-old rats compared with the 6-wk-old rats (P = 0.003). Taken together, the quantitative and molecular nNOS changes in the stomach might play a role in the decrease of gastric accommodation with age. [ABSTRACT FROM AUTHOR]

Objective: The effectiveness ofHelicobacter pyloritherapies has declined with an increase in antibiotic resistance. To overcome this problem, the efficacy of tailoredH. pylorieradication therapy based on antimicrobial susceptibility testing was compared with that of empirical second-line rescue regimens.Material and methods: Patients who had persistentH. pyloriinfection after the first eradication were recommended to undergo culture for determining the minimal inhibitory concentration (MIC) via gastroscopy, which increased the cost by 300%. Fourteen-day esomeprazole, tripotassium dicitrate bismuthate, metronidazole and tetracycline (EBMT) therapy or esomeprazole, moxifloxacin and amoxicillin (MEA) therapy was performed according to the results of antibiotic susceptibility testing. In case of refusal to undergo culture, the participants were treated with either 14-day empirical EBMT or MEA regimen for second eradication after explaining the complexity, side effects and costs associated with each regimen. This trial was registered at ClinicalTrials.Gov (NCT 02349685).Results: In the 219 patients included, the intention to treat (ITT) and per protocol (PP) eradication rates was 75.3% and 79.8% in the 14-day EBMT group (n=89), 70.8% and 72.4% in the 14-day MEA group (n=89) and 87.8% and 100.0% in the 14-day tailored therapy group (n=41), respectively. Based on the PP analysis, the 14-day tailored therapy group showed a significantly higher eradication rate than the 14-day EBMT or MEA group (bothp ≤ 0.001).Conclusions: Tailored therapy based onH. pyloriculture and MIC test could be an option as a second-line eradication regimen in the presence of high level of antimicrobial resistance. [ABSTRACT FROM PUBLISHER]

Background The 13C-urea breath test (13C- UBT) is a noninvasive method for diagnosing Helicobacter pylori ( H. pylori) infection. The aims of this study were to evaluate the diagnostic validity of the 13C- UBT cutoff value and to identify influencing clinical factors responsible for aberrant results. Methods 13C- UBT ( UBiTkit; Otsuka Pharmaceutical, cutoff value: 2.5‰) results in the range 2.0‰ to 10.0‰ after H. pylori eradication therapy were compared with the results of endoscopic biopsy results of the antrum and body. Factors considered to affect test results adversely were analyzed. Results Among patients with a positive 13C- UBT result (2.5‰ to 10.0‰, n = 223) or a negative 13C- UBT result (2.0‰ to < 2.5‰, n = 66) after H. pylori eradication, 73 patients (34.0%) were false positive, and one (1.5%) was false negative as determined by endoscopic biopsy. The sensitivity, specificity, false-positive rate, and false-negative rate for a cutoff value of 2.5‰ were 99.3%, 47.1%, 52.9%, and 0.7%, respectively, and positive and negative predictive values of the 13C- UBT were 67.3% and 98.5%, respectively. Multivariate analysis showed that a history of two or more previous H. pylori eradication therapies ( OR = 2.455, 95% CI = 1.299-4.641) and moderate to severe gastric intestinal metaplasia ( OR = 3.359, 95% CI = 1.572-7.178) were associated with a false-positive 13C- UBT result. Conclusion The 13C- UBT cutoff value currently used has poor specificity for confirming H. pylori status after eradication, and this lack of specificity is exacerbated in patients that have undergone multiple prior eradication therapies and in patients with moderate to severe gastric intestinal metaplasia. In addition, the citric-free 13C- UBT would increase a false-positive 13C- UBT result. [ABSTRACT FROM AUTHOR]

This paper presents the modeling methodology of Zn diffusion process utilized for high-speed avalanche photodiode fabrication using neural networks. The modeling scheme can characterize the effects of diffusion process conditions on the performance metrics of diffusion process. Three different InP-based test structures with different doping concentrations in diffused layer are explored. Three input factors (sealing pressure, amount of Zn3P2 source per volume, and doping concentration of diffused layer) are examined with respect to the two performance metrics (diffusion-rate and Zn doping concentration) by means of D-optimal design experiment. Diffusion rate and Zn doping concentration in diffused layer are characterized by a response model generated by training feed-forward error back-propagation neural networks. It is observed that the neural network based process models developed here exhibit good agreement with experimental results. [Copyright &y& Elsevier]

Background: As the prevalence of antibiotic resistance is increasing, the effectiveness of traditional Helicobacter pylori (H pylori) therapies is gradually declining. We aimed to evaluate the efficacy of tailored therapy (dual priming oligonucleotide [DPO]‐based multiplex PCR) and previous antibiotic exposure survey predicting for antibiotic resistance. Materials and Methods: Patients with H pylori infection who did not receive previous treatment were enrolled. The patients were divided into four groups (no resistance [NR] group, clarithromycin resistance [CLA‐R] group, metronidazole‐resistant [MET‐R] group, and CLA‐ and MET‐resistant [Dual‐R] group) based on the results of dual priming oligonucleotide (DPO) polymerase chain reaction (PCR) and previous antibiotic exposure survey, and they were treated with tailored therapy based on antibiotic susceptibility. Results: Consecutive patients were distributed in the NR (n = 36, 70.6%), CLA‐R (n = 9, 17.6%), and suspected MET‐R (n = 6, 11.8%) group. The overall intention‐to‐treat/per‐protocol eradication rate (ITT/PP) was 92.2%/94.0%. In the subgroup analysis, the ITT and PP of the NR, CLA‐R, and MET‐R groups were 94.4%/94.4%, 77.8%/87.5%, and 100.0%/100.0%, respectively. Total of 31 patients in all subgroups were evaluated for antibiotic resistance; five (16.1%), two (6.5%), and three (9.7%) participants showed CLA, MET, and dual resistance in culture‐based susceptibility test. Compared with culture‐based MIC test, the accuracy of DPO‐based multiplex PCR in determining CLA resistance was 90.3%, while the accuracy of survey in determining MET resistance was only 77.4%. Conclusion: A tailored therapy based on DPO‐PCR and history of previous antibiotic use is useful in clinical practice and well correlated with culture‐based susceptibility test. [ABSTRACT FROM AUTHOR]

Xenopus laevis is highly suitable as a toxicology animal model owing to its advantages in embryogenesis research. For toxicological studies, a large number of embryos must be handled simultaneously because they very rapidly develop into the target stages within a short period of time. To efficiently handle the embryos, a convenient embryo housing device is essential for fast and reliable assessment and statistical evaluation of malformation caused by toxicants. Here, we suggest 3D fabrication of single-egg trapping devices in which Xenopus eggs are fertilized in vitro, and the embryos are cultured. We used manual pipetting to insert the Xenopus eggs inside the trapping sites of the chip. By introducing a liquid circulating system, we connected a sperm-mixed solution with the chip to induce in vitro fertilization of the eggs. After the eggs were fertilized, we observed embryo development involving the formation of egg cleavage, blastula, gastrula, and tadpole. After the tadpoles grew inside the chip, we saved their lives by enabling their escape from the chip through reverse flow of the culture medium. The Xenopus chip can serve as an incubator to induce fertilization and monitor normal and abnormal development of the Xenopus from egg to tadpole. • Xenopus chip as an embryo housing device. • In vitro fertilization of Xenopus eggs inside the chip. • Tadpole trapping and escape processes. [ABSTRACT FROM AUTHOR]

Epstein–Barr virus (EBV)-associated gastric cancer (EBVaGC) is a distinct molecular subtype of gastric cancer. This study aims to investigate genomic and clinicopathological characteristics of EBVaGC according to the histological pattern. We retrospectively collected 18 specimens of surgically resected EBVaGCs. Whole-exome sequencing was performed for all cases. Moreover, PD-L1 expression and tumor-infiltrating lymphocyte (TIL) percentage were investigated. Among 18 EBVaGCs, 10 cases were of intestinal histology, 3 were of poorly cohesive histology, and the remaining 5 were of gastric carcinoma with lymphoid stroma histology. Whole-exome sequencing revealed that EBVaGCs with intestinal histology harbored pathogenic mutations known to frequently occur in tubular or papillary adenocarcinoma, including TP53, KRAS, FBXW7, MUC6, ERBB2, CTNNB1, and ERBB2 amplifications. One patient with poorly cohesive carcinoma histology harbored a CDH1 mutation. Patients with EBVaGCs with intestinal or poorly cohesive carcinoma histology frequently harbored driver mutations other than PIK3CA, whereas those with EBVaGCs with gastric carcinoma with lymphoid stroma histology lacked other driver mutations. Moreover, the histological pattern of EBVaGCs was significantly associated with the levels of TILs (P = 0.005) and combined positive score (P = 0.027). In conclusion, patients with EBVaGCs with different histological patterns exhibited distinct genetic alteration, PD-L1 expression, and degree of TILs. [ABSTRACT FROM AUTHOR]

Background: The inappropriate selection of patients with early gastric cancer (EGC) for endoscopic submucosal dissection (ESD) may lead to additional surgery because of a non-curative resection. This study was performed to assess the accuracy of clinical decisions in ESD for EGC.Methods: A total of 607 cases of EGC treated by ESD were prospectively enrolled from January 2011 to June 2014 at a single academic hospital. The 607 EGCs were divided into three groups (overestimated, same-estimated, and underestimated) based on pre-procedure endoscopic findings (indication) and pathological diagnosis after ESD (criteria). We evaluated the discrepancy rates between pre-procedure indication and pathological criteria, and then analyzed the pre-procedure factors that could influence the occurrence of the discrepancies.Results: The absolute, expanded, and beyond the expanded indication has its accuracy on curability criteria in 87%, 77.6%, and 55.6% of cases, respectively. The ratio of overall indication-criteria discrepancies was 250/607 (41.2%). The curability was significantly lower in the underestimated group compared to the overestimated and same-estimated groups (41.6% vs. 94.6%, 94.4%, p < 0.001). In multivariate analysis examining the predictive factors for discrepancies in the 598 EGCs with absolute/expanded indications, the endoscopic size ≥ 20 mm [odds ratio (OR) 2.493, confidence interval (CI) 1.546-4.022, p < 0.001], presence of ulcers (OR 1.712, CI 1.070-2.738, p = 0.025), patient age < 60 years (OR 1.689, CI 1.044-2.733, p = 0.033), and undifferentiated type EGC on forceps biopsy (OR 5.397, CI 2.027-14.369, p = 0.001) were all associated with discrepancies.Conclusions: Indication judged by pre-procedural endoscopy is not sufficiently accurate to be used as a good measurement for post-procedural criteria. [ABSTRACT FROM AUTHOR]

Abstract: Background and Aim: rdxA and frxA mutations and enhancement of efflux pump have been suggested as the cause of metronidazole resistance in Helicobacter pylori. This study was performed to investigate the resistance mechanisms related to clinical eradication outcome, and to examine direct involvement of hefA in metronidazole‐resistant isolates with intact rdxA and frxA. Methods: A total of 53 H. pylori‐positive patients who were treated with metronidazole‐containing sequential or quadruple therapy from 2011 to 2015 were enrolled. The metronidazole susceptibility of H. pylori isolates was examined by agar dilution test. Mutations in rdxA and frxA, were analyzed with DNA sequencing, and impact of hefA on metronidazole resistance was examined with quantitative real‐time reverse transcription polymerase chain reaction, knockout and genetic complementation test for hefA. Results: Seven mutation types of rdxA and/or frxA were found in H. pylori isolated from non‐eradicated subjects. rdxA mutation was associated with eradication failure (P = 0.002), and nonsense mutation in rdxA reduced eradication efficacy (P = 0.009). hefA expression was significantly higher in resistant isolates (P < 0.001), especially in rdxA(−)frxA(−) as compared to rdxA(+)frxA(+) (P = 0.027). Resistant isolates with no mutation in rdxA and frxA became susceptible after hefA knockout. Genetic complementation for hefA recovered metronidazole resistance in all of three hefA knockout mutants. Conclusions: These results suggest that rdxA mutations play a critical role in metronidazole resistance as well as the outcomes of eradication therapy. In addition, hefA seems to be directly involved in metronidazole resistance, which explains the resistance in clinical isolates with intact rdxA and frxA. [ABSTRACT FROM AUTHOR]

The effect of GaAs[sub y]P[sub 1-y](0≤y<1) interlayers on the characteristics of GaAs/InGaP heterojunction has been investigated. For samples having GaAs[sub y]P[sub 1-y] interlayers in the range of 0

Time-resolved photoluminescence has been employed to study the donor-acceptor pair recombination kinetics of the yellow (∼2.3 eV) and blue (∼2.8 eV) luminescence bands in Si- and Mg-doped GaN layers, respectively. As the Si doping concentration in Si-doped GaN increases, the lifetime τ[sub 1/e] of the yellow luminescence decreases, indicating that a shallow Si donor is the origin of the yellow luminescence. The blue luminescence is most likely due to a shallow Mg acceptor and a deep donor composed of a Mg acceptor-nitrogen vacancy complex, as seen by the independence of τ[sub 1/e] on the Mg concentration measured by secondary ion mass spectroscopy in the range (2.5-6.0)x10[sup 19] cm[sup -3]. As the temperature is increased from 10 to 300 K, the lifetimes for the yellow and blue luminescence remain nearly constant, indicating that the distribution of electrons and holes bound to donors and acceptors does not change much with increasing temperature. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Background: The presence of atrophic gastritis (AG) and intestinal metaplasia (IM) is associated with an increased risk of gastric cancer (GC). Thus, the development of new strategies to improve AG/IM is essential for reducing the incidence of GC. Aims: We aimed to evaluate the efficacy of rebamipide for improving AG/IM. Methods: This was a prospective, randomized, pilot study from a single tertiary referral center. Fifty-three (rebamipide, n = 34 vs. placebo, n = 19) patients, who underwent endoscopic resection for gastric dysplasia or early GC, were analyzed. We obtained tissue samples from the antrum and corpus of the stomach, at the time of screening and 1-year later. The histologic grading of inflammation was performed by histopathologists Results: The AG grade in the antrum improved significantly after rebamipide treatment (pre-administration, 1.870 ± 0.932 vs. post-administration, 1.430 ± 0.986; P = 0.013). Additionally, the severity of IM in the antrum was significantly improved (pre-administration, 1.750 ± 0.963 vs. post-administration, 1.370 ± 1.032; P = 0.038). The rebamipide subgroup analysis revealed that patients with no Helicobacter pylori (HP) infection showed significant improvements in AG in the antrum (pre-administration, 1.880 ± 1.040 vs. post-administration, 1.250 ± 0.894; P = 0.028) and IM in antrum (pre-administration, 1.840 ± 1.012 vs. post-administration, 1.180 ± 0.912; P = 0.020). Conclusions: This study demonstrated that the administration of rebamipide improves AG and IM in the antrum, especially in patients with HP non-infection (KCT0001915). [ABSTRACT FROM AUTHOR]

Integration of a 40-Gb/s electroabsorption modulator integrated distributed feedback (DFB) laser (EML) module with a driver amplifier and bias tee was investigated. For the EML fabrication the selective area growth (SAG) technique was adopted for the first time. It is shown that, with the SAG technique, the 3.dB bandwidth of about 45 GHz was measured in the electrical to optical response, and the return loss (S11) of below -10 dB was achieved for up to 50 GHz. To integrate a bias tee within the module, a right-angle bent coplanar waveguide (CPW) was developed. The right-angle bent CPW was characterized with 511 of below -10 dB for up to 35 GHz and insertion loss (S21) of about -1.4 dB for up to 40 GHz. The whole integrated module including the EML, a driver amplifier, and bias tee was characterized under the conditions of an operating temperature of 25 ° C, the modulator bias of 1.4 V, and the DFB laser current of 40 mA. 511 of below -10 dB was obtained for up to 14 GHz and the measured electrical-to-optical response has 3-dB bandwidth of about 20 GHz. [ABSTRACT FROM AUTHOR]

Abstract: The post-annealing effect on the dark current of the InGaAs waveguide photodiodes, which are developed for 40-Gbps optical receiver applications, is experimentally investigated. The interesting experimental phenomena were observed that the dark current is significantly decreased and the breakdown voltage is slightly increased after annealing at 250 and 300°C whereas the dark current and the breakdown voltage are almost constant after annealing at 200°C. Based on the experimental results, the post-annealing is more effective for the dark current improvement than the conventional curing process. [Copyright &y& Elsevier]

Background: Helicobacter pylori infection and hyperplastic polyp are known to have strong connections, but there are not enough randomized controlled trial data. Aims: To evaluate the effect of H. pylori eradication on gastric hyperplastic polyp. Method: This is an open-labeled, single-center, randomized controlled trial. Patients with hyperplastic polyp and current infection of H. pylori were randomly assigned to eradication or non-eradication groups. All participants underwent follow-up endoscopy to investigate the regression of gastric polyps. Gastric polyp regression was defined as the disappearance of polyps or a reduction of more than 50% in size. Results: Thirty-two patients were randomized to eradication (n = 17) and non-eradication groups (n = 15). Final included patients were 14 in eradication group and 13 in non-eradication group. All patients showed polyp regression in eradication group, whereas no regression was observed in non-eradication group (P < 0.001). Disappearance of polyp (n = 7) and decrease in size (n = 7) were observed in eradication group. In non-eradication group, no change (n = 5), increase of size (n = 5), and increase of number (n = 3) were observed. Mean regression time was 6.8 months, and disappearance time was 9.8 months. In non-eradication group, hyperglycemia was noted in 50% of progression group but not noted in no change group (P = 0.057). Conclusions: H. pylori eradication induced regression of hyperplastic polyp, and persistent H. pylori infection was related to progression of gastric polyp. Clinical Trial Registration: ClinicalTrials.gov ID: NCT03065868 [ABSTRACT FROM AUTHOR]

The remote sensing of algal pigments is essential for understanding the temporal and spatial distribution of harmful algal blooms (HABs). In particular, the vertical distribution of cyanobacterial pigment (e.g., phycocyanin (PC)) is critical factor in remote sensing because the diel vertical migration of cyanobacteria may affect the spectral signals according to observational time. Although numerous studies have been conducted on the remote sensing of algal bloom using pigments, few studies considered the vertical distribution of the pigments for the remote sensing of cyanobacteria in inland waters. In this regard, the objective of this study was to develop an improved bio-optical remote-sensing method using in-situ remote-sensing reflectance (Rrs) at different water depths and cumulative PC and Chlorophyll-a (Chl-a) concentrations, which was cumulated from the surface to a 5-m water depth. The results showed that the bio-optical algorithm using surface Rrs and surface pigment concentration was more accurate than that using the subsurface Rrs and surface pigments. The bio-optical algorithm using subsurface Rrs showed the highest R-squared (R2) values (0.87–0.94) in each regression with the cumulative PC concentration from surface to each depth. The regressions between drone-based surface reflectance and cumulative PC concentration for each depth indicated a better performance than those between the reflectance and surface PC concentration; the highest R2 value of 0.82 was obtained from a bio-optical algorithm using drone-based reflectance and a 1.0-m cumulative PC concentration, which was the best-performing algorithm. The PC maps developed using the best bio-optical algorithm accurately described the spatial and temporal distributions of the PC concentrations in the reservoir. This study demonstrates that the application of vertical cumulative pigment concentration and subsurface Rrs measurement in bio-optical algorithms can improve their performance in estimating pigments, and that drone-based hyperspectral imagery is an efficient tool for the remote sensing of cyanobacterial pigments over a wide area. • Cumulative pigment and subsurface Rrs were used to construct bio-optical algorithms. • Vertical cumulative pigment concentration was highly correlated with subsurface Rrs. • PC map was developed using drone hyperspectral imagery and cumulative concentration. • Relative abundance of PC was readily detectable by cumulative PC distribution map. [ABSTRACT FROM AUTHOR]

Objective. The serum pepsinogen test has limitation in its predictive power as a noninvasive biomarker for gastric cancer screening. We aimed to investigate whether the combination of TFF3 and pepsinogen could be an effective biomarker for the detection of gastric cancer even in the early stages. Methods. In total, 281 patients with early gastric cancer (EGC), who underwent endoscopic submucosal dissection in Korea, and 708 healthy individuals from Japan were enrolled in the derivation cohort. The validation cohort included 30 Korean patients with EGC and 30 Korean healthy control blood donors. Serum TFF3 levels were examined using enzyme-linked immunosorbent assay. Results. Using a cutoff of 6.73 ng/mL in the derivation cohort, the sensitivity of the combination of tests for EGC detection was superior (87.5%) to that of TFF3 (80.4%) or pepsinogen test alone (39.5%). Similarly, in the validation cohort, the sensitivity of TFF3 plus pepsinogen was higher (90.4%) than that of TFF3 (80.0%) or pepsinogen test alone (33.3%). Conclusion. The combination of serum TFF3 and pepsinogen is a more effective noninvasive biomarker for gastric cancer detection compared with pepsinogen or TFF3 alone, even in EGC. This trial is registered with NCT03046745. [ABSTRACT FROM AUTHOR]

Background: After endoscopic submucosal dissection (ESD) for early gastric cancer (EGC), negative pathological findings cause concern about the adequacy of the procedure and local recurrence after ESD.Aim: To investigate the incidence of local recurrence in cases with negative pathological findings after ESD for EGC and pathologically complete resection (CR) during long-term follow-up.Methods: We reviewed 453 patients who underwent ESD for ECG from January 2007 to December 2010, respectively. Of these patients, in 17 cases the pathology results confirmed no residual tumor (NRT), and in 421 cases they showed CR in the ESD specimen. Finally, 17 NRT and 358 CR cases were followed up during surveillance. Patient characteristics, endoscopic and pathological data were analyzed for risk factors of local recurrence. We also re-evaluated the pathology of the NRT group to identify hidden malignant cells in the previous ESD specimens.Results: There was no difference between the two groups in terms of recurrence during follow-up surveillance (median 55.7 months). Late local recurrence of EGC was found in two cases (11.8%) in the NRT group, and three early local recurrences (5.6%) were found in the CR group. A review of the pathology in the NRT group revealed hidden malignant cells in five patients (29.4%).Conclusions: Even when the pathological report indicates NRT after ESD, it might be necessary to re-evaluate ESD specimens with a width <2 mm, and long-term endoscopic surveillance should be routinely used for detecting local EGC recurrence after ESD. [ABSTRACT FROM AUTHOR]

ABSTRACT This article describes the successful development and the performance of X-band 100 W pulsed SSPA using a 25 W GaN-on-SiC high electron mobility transistor (HEMT). The GaN HEMT with a gate length of 0.25 µm and a total gate width of 8 mm were fabricated. The GaN HEMT provide a linear gain of 8 dB with 25 W output power operated at 30 V drain voltage in continuous wave (CW)-operation with a power added efficiency of 43% at X-band. It also shows a maximum output power density of 3 W/mm. The X-band pulsed SSPA exhibited an output power of 100 W (50 dBm) with a power gain of 53 dB in a frequency range of 9.2-9.5 GHz. This 25 W GaN HEMT and X-band 100 W pulsed SSPA are suitable for the radar systems and related applications in X-band. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:212-216, 2015 [ABSTRACT FROM AUTHOR]

Highlights: [•] Normally-off dual gate AlGaN/GaN MISFET with a selective area-recessed floating gate was proposed. [•] The proposed device showed the enhanced off-state blocking voltage, corresponding to the simulation data. [•] The device showed the negligible degradation of the on-state performance. [•] The device showed a low subthreshold slope and a low gate leakage current. [Copyright &y& Elsevier]

Abstract: 19-Gb/s transmission over 23-km SMF is demonstrated based on 1-GHz bandwidth limited RSOAs with adaptively modulated optical OFDM. A novel baseband transmission technique is applied to halve the sampling speed requirements compared to traditional OFDM transmission techniques using Hermitian Symmetric. Selective bit loading with pre-emphasis and compensation is used to optimize the transmission performance. [Copyright &y& Elsevier]

Planar InP/InGaAs avalanche photodiodes are widely used for high-speed optical receivers in optical fiber communication systems. Even though these avalanche photodiodes offer the excellent characteristics in high-speed operation, the performance metrics are affected by manufacturing parameter variations considerably. In this paper, the effects of manufacturing variations on the device performance are investigated. In order to build a photodiode model, the test structures were fabricated and the measured current–voltage characteristics were compared with the simulated data to verify the model. After the model verification, the variations of the breakdown voltage and punch-through voltage according to the different manufacturing parameters such as multiplication layer width and charge sheet density are examined. Based on the results, the manufacturability of the avalanche photodiodes can be improved by analyzing the manufacturing variations. [Copyright &y& Elsevier]

Remote sensing can detect and map algal blooms. The HydroLight (Sequoia Scientific Inc., Bellevue, Washington, DC, USA) model generates the reflectance profiles of various water bodies. However, the influence of model parameters has rarely been investigated for inland water. Moreover, the simulation time of the HydroLight model increases as the amount of input data increases, which limits the practicality of the HydroLight model. This study developed a graphical user interface (GUI) software for the sensitivity analysis of the HydroLight model through multiple executions. The GUI software stably performed parameter sensitivity analysis and substantially reduced the simulation time by up to 92%. The GUI software results for lake water show that the backscattering ratio was the most important parameter for estimating vertical reflectance profiles. Based on the sensitivity analysis results, parameter calibration of the HydroLight model was performed. The reflectance profiles obtained using the optimized parameters agreed with observed profiles, with R2 values of over 0.98. Thus, a strong relationship between the backscattering coefficient and the observed cyanobacteria genera cells was identified. [ABSTRACT FROM AUTHOR]

A new simple method to obtain real‐time high‐resolution three‐dimensional (3D) images based on a static unitary detector (STUD) is reported. The STUD consists of a common bias network, a partitioned photodetector, a preamplifier array and a combiner, which makes it possible to easily increase the effective photo‐detection area for a wider 3D image acquisition without affecting the ability to detect short laser pulses for high‐resolution 3D images. From an implemented experimental prototype based on a STUD, the intensity and 3D images with a very high resolution (320 pixels × 240 pixels) were obtained. The achieved range resolution and the spatial resolution of remote 3D objects at 50 m were measured to be <0.3 and 1.1 cm, respectively. [ABSTRACT FROM AUTHOR]