Measurement of the remnant magnetic-field in Lorentz mode using permalloy

A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.

Effective Mass of Acoustic Polaron in Quantum Dots

The variational effective mass with respect to the e-p coupling constant for different values of cutoff wave vector is performed in quantum dot. The self-trapping transition of acoustic polaron in quantum dot is reconsidered by character of the effective mass curve varying with the e-p coupling. The holes are determined to be self-trapped in AlN quantum dot systems.

桑叶及其提取物对肠道功能的调节作用

自古以来桑叶就有显著的肠道调节作用。本文综述了近年来研究桑叶的相关文章,总结了桑叶成分的生物活性和其对人体肠道调节作用的研究进展及相应的机制。桑叶中的多种成分可以单独或协同影响人体肠道,通过直接和间接的方式促进小肠消化吸收运输功能、调节菌群平衡以及增强肠道黏膜的屏障作用来提高该部位的免疫力等,促进肠道疾病的康复。

InGaAs/InAlAs SAGCMCT avalanche photodiode with high linearity and wide dynamic range

Linearity is a very important parameter to measure the performance of avalanche photodiodes(APDs) under high input optical power. In this paper, the influence of the absorption layer on the linearity of APDs is carefully studied by using bandgap engineering with the structure model of separated absorption, grading, charge, multiplication, charge, and transit(SAGCMCT). The simulated results show that in the hybrid absorption layer device structure the 1 d B compression point can be improved from-9 d Bm to-2.1 d Bm by increasing the proportion of the p-type absorption layer. In the device structure with only one absorption layer, increasing the doping level of the absorption layer can also improve the 1 d B compression point from-8.6 d Bm to 1.43 d Bm at a gain of 10. Therefore, the absorption layer is very critical for the linearity of APDs.

Integrated optoelectronic chip pair for transmitting and receiving optical signals simultaneously

An integrated optoelectronic chip pair, which can transmit and receive optical signals simultaneously, is proposed in this Letter. The design and optimization of its key structure, the vertical cavity surface emitting laser's distributed Bragg reflector, are presented. Analysis is also done for its influence on the integrated chip's performance. Moreover, the chip pair's performance under dynamic conditions is analyzed. Their 3 dB modulation bandwidths are higher than 10 GHz, and their 3 dB photo-response bandwidths are around 23 GHz. Their applications will further improve the performances of the optical interconnects.

A pair of integrated optoelectronic transceiving chips for optical interconnects

In this Letter, a pair of integrated optoelectronic transceiving chips is proposed. They are constructed by integrating a vertical cavity surface emitting laser unit above a positive-intrinsic-negative photodetector unit. One of the transceiving chips emits light at the wavelength of 848.1 nm with a threshold current of 0.8 mA and a slope efficiency of 0.81 W/A. It receives light between 801 and 814 nm with a quantum efficiency of higher than 70%. On its counterpart, the other one of the transceiving chips emits light at the wavelength of 805.3 nm with a threshold current of 1.1 mA and a slope efficiency of 0.86 W/A. It receives light between 838 and 855 nm with a quantum efficiency of higher than 70%. The proposed pair of integrated optoelectronic transceiving chips can work full-duplex with each other, and they can be applied to single fiber bidirectional optical interconnects.

Research on photodiode integrated with wide spectrum focusing reflector using nonperiodic subwavelength gratings

The fabrication and characterization of p-i-n photodiodes integrated with wide spectrum focusing reflectors using nonperiodic strip and concentric-circular subwavelength gratings are presented. The experimental results show that the gratings can reflect and focus the incident light on the absorber of the photodiode, and thus can simultaneously achieve high speed and high efficiency. For the gratings’ integrated photodiodes, the responsivity is improved over a wide spectral range, and when the absorber was 600 nm and the mesa diameter was40 μm, a responsivity of 0.46 A/W at a wavelength of 1.55 μm and a 3 dB bandwidth of 21.6 GHz under a reverse bias of 3 V were simultaneously obtained.

Quasi-resonant cavity enhanced photodetector with a subwavelength grating

We designed a tunable wavelength-selective quasi-resonant cavity enhanced photodetector(QRCE-PD)based on a high-contrast subwavelength grating(SWG).According to simulation results,its peak quantum efficiency is 93.2%the 3 dB bandwidth is 33.5 GHz,the spectral linewidth is 0.12 nm,and the wavelength-tuning range is 28 nm(1536-1564 nm).The QRCE-PD contains a tunable Fabry-Perot(F-P)filtering cavity(FPC),a symmetrical SWG deflection reflector(SSWG-DR),and a built-in p-i-n photodiode.The FPC and the SSWG-DR form an equivalent multi-region F-P cavity together by multiple mutual mirroring,which makes the QRCE-PD a multi-region resonant cavity enhanced photodetector.But,QRCE-PD relies on the multiple-pass absorption enhanced effect to achieve high quantum efficiency,rather than the resonant cavity enhanced effect.This new photodetector structure is significant for the application in the dense wavelength division multiplexing systems.

Bias-free operational monolithic symmetric-connected photodiode array

We have designed and fabricated zero-bias operational two-element symmetric-connected photodetector arrays(SC-PDAs).The designed SC-PDAs have higher saturation currents,larger RF power,and better frequency responses than the single photodetector(PD)under zero bias.The bias-free SC-PDA with 15μm diameter of each PD demonstrated a 3 d B bandwidth of 19.4 GHz at 0.5 m A.The RF saturation photocurrent and maximum RF output power of the SC-PDA with 40μm,50μm,and 60μm diameters under zero bias are over9.31 m A and-5.86 d Bm at 3 GHz,14.52 m A and 1.17 d Bm at 1 GHz,and 13.72 m A and-1.76 d Bm at 1 GHz,respectively.

Flat transmitted serrated-phase high-contrast-index subwavelength grating beam splitter

We proposed a method to form a flat transmitted serrated-phase(SP) high-contrast-index subwavelength grating(HCG) beam splitter(HBS) for all dielectric materials, which is to alternately arrange two kinds of grating bars with a phase difference of π. Compared to the typical linear-phase(LP) HBS, which consists of two symmetrical deflecting gratings, the SP-HBS is extensible in size, and can achieve excellent splitting ability regardless of normal incidence or small-angle oblique incidence with large deflection angles, higher diffraction efficiency,lower energy loss, and higher tolerance of fabrication accuracy. Furthermore, the incident light can be split in half at any part of the SP-HBS, and the output beams of light maintain the original shape. In this Letter, we designed an SP-HBS with a 44.8° deflection angle and a 90.28% transmissivity.

Prospective study of the short-term effect of 1.75 mmol/L calcium concentration dialysate on hemodialysis patients

Objective:The purpose of the current study was to determine the influence of a 1.75 mmol/L calcium(Ca)concentration dialysate(DCa 1.75)during maintenance hemodialysis(MHD)therapy for patients with chronic kidney disease,mineral,and bone disorders(CKD-MBD)on biochemical indices and clinical prognosis.Methods:Four hundred eighty-three MHD patients from three hemodialysis centers were en-rolled.During 24 months of follow-up(January 2011 to December 2012),289 patients from Center 1 who used 1.50 mmol/L Ca concentration dialysate(Dca 1.50)between January and December 2011 and DCa 1.75 between January and December 2012 were included in the high Ca group.The remaining 194 patients from the other centers who used DCa 1.50 for hemodialysis between January 2011 and December 2012 were included in the ordinary Ca group.The following CKD-MBD biochemical indices were monitored:blood Ca;blood phosphorus(P);intact parathyroid hormone(iPTH);and bone-specific alkaline phosphatase(BAP).The metastatic calcification index included calcification of aortic arch scoring(AoACS),abdominal aorta calcification(AAC),and cardiac valve calcification(CVC).The study end points included all-cause mortality(ACM),car-diovascular and cerebrovascular diseases(CCVDs),fractures,and new metastatic calcifications.The changes between the two groups in the observed indices were compared.Results:Two hundred eighty-four patients in the high Ca group(98.3%)and 194 patients in the ordinary Ca group(100.0%)completed an average follow-up of 21.3±5.6 months.After DCa 1.75 was used,the blood Ca in the high Ca group increased[(2.39±0.22)mmol/L vs.(2.34±0.21)mmol/L,t=-2.910,P=0.004]compared to the previous year,and increased[(2.39±0.22)mmol/L vs.(2.30±0.16)mmol/L,t=5.187,P<0.001]compared to the ordinary Ca group in the same year.The blood P and iPTH decreased[(1.78±0.39)mmol/L vs.(1.89±0.42)mmol/L,t=2.909,P=0.004 and(306.5±298.6)pg/ml vs.(425.7±365.1)pg/ml,t=8.377,P<0.001,respectively]compared with the previous year,and decreased[(1.78±0.39)mmol/L vs(1.86±0.39)mmol/L,t=-2.016,P=0.044 and(306.5±298.6)pg/ml vs.(366.6±341.0)pg/ml,t=-2.113,P=0.035,respectively]compared with the ordinary Ca group in the same year.There was no difference in AoACS between the two groups before and after the change in DCa in the high Ca group(P>0.05).In 2011,there was 13 CCVDs,2 fractures,and 13 new metastatic calcifications in the ordinary Ca group compared to 8 CCVDs,3 fractures,and 16 new metastatic calcifications in the high Ca group;there were no statistically significant differences in the incidence of end point events between the two groups(χ^(2)=2.747,P=0.098).In 2012,the values for the ordinary Ca group were 13,2,and 15,respec-tively,while the values for the high Ca group were 8,1,and 19,respectively,which indicated a statistically significant difference in the incidence of end point events between the two groups(χ^(2)=4.391,P=0.036).Conclusion:Short-term use of DCa 1.75 significantly reduced the blood P and iPTH levels in MHD patients,significantly increased the blood Ca level,did not increase the proportion of new cardiovascular calcifications,and decreased the overall inci-dence of end point events.