Novel Ka-band low-noise down-converter assembly

An efficient way to design a down-converter assembly for the Ka-band millimeter system is presented, in which dielectric resonators （DR＇s） are adopted in the Schottky barrier diode image recovery mixer and the local oscillator （LO）. DR structures guarantee high frequency stability with an acceptable volume. The configurations of low noise amplifier, mixer and oscillator in the assembly are described and fabricated to estimate the chain performance. According to the verification results, the assembly exhibits the noise figure of less than 5 dB over 1 GHz frequency range, and the single-sideband phase noise （200 kHz offset from carrier frequency） of - 70 dBc/Hz. Utilizing the DR structure, the frequency stability of the local oscillator is less than 60 × 10^-6/℃.

Quad-channel broadband compact multi-antenna GNSS down-converter for high-reliability navigation

A high-reliability broadband high-linearity down-converter for multi-antenna global navigation satellite system(GNSS)receiver is presented in this paper.Based on direction-of-arrival estimation,the multi-antenna GNSS receiver can separate the GNSS signals from the interfering signals and suppress harmful broadband radio frequency interferences.To drive the off-chip 50Ω2 resistive load and meet the stringent requirements of linearity,a quad-channel down-converter with a broadband common-gate low-noise transcon-ductance amplifier,current-driven passive mixer and novel bridge mode transimpedance driving amplifier have been proposed to contruct the multi-antenna recelver.The operating frequency of this down-converter is from 1.15 to 1.65 GHz,covering all bands for global positioning system(GPS),Beidou navigation satellite system(BDS),global navigation satellite system(GLONASS)and Galileo.The measured results show that the proposed quad-channel down-converter achieves+38 dBm output 3rd order intercept point(OIP3)and+17 dBm OP1dB(output-referred 1 dB compression point),9.5 dB to 12.9 dB noise figure(NF)across the variable gain of 10 dB to 27 dB and approximately 47 dB channel isolation.

Efficient structures for wideband digital receiver

Digital receivers have become more and more popular in radar, communication, and electric warfare for the advantages compared with their analog counterparts. But conventional digital receivers have been generally considered impractical for bandwidth greater than several hundreds MHz. To extend receiver bandwidth, decrease data rate and save hardware resources, three novel structures are proposed. They decimate the data stream prior to mixing and filtering, then process the multiple decimated streams in parallel at a lower rate. Consequently it is feasible to realize wideband receivers on the current ASIC devices. A design example and corresponding simulation results are demonstrated to evaluate the proposed structures.

Syntheses of Novel Asymmetric Cyclopentanone Dyes and Measurement of Two-photon Absorption Cross-section

A simple synthesis route with a high yield of novel asymmetric cyclopentanone dyes 3a-3e and their highly two-photon up-converted fluorescences are reported. The dyes have good solubilities in most of ordinary solvents, a wide UV absorption wavelength range from 380-540 nm, and high fluorescence quantum yields. The two-photon absorption cross-sections of dyes 3a-3e were measured in chloroform by a two-photon induced fluorescence method. All of these properties of the new dyes make them suitable for being used as two-photon fluorescent probes.

Study of Software Radio Receiver Development Platform

The Paper introduces an IF software radio receiver development Platform based on high-speed monolithic A/D Converter AD6640, Progranunable Digital Down-converter AD6620 and high-speed DSP chip TMSC320C6701. The implementation method is described as well as AD6620 parameter setting analysis. It also presents a flow chart of the on-line programming with the help of PC. The algorithm for demodulation AM signal is discussed.

Enhancing the performance of photovoltaic cells by using down-converting KCaGd(PO_4)_2:Eu^(3+) phosphors

The goal of this work is aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic （PV） cells by using the solar spectral conversion principle, which employed a down-converting phosphor to convert a high-energy ultraviolet photon to the less energetic red-emitting photons to improve the spectral response of Si solar cells. In this study, the surface of silicon solar cells was coated with a red-emitting KCaGd（PO4）2：Eu3＋ phosphor by using the screen-printing technique. In addition to the investigation on the microstructure using scanning electron microscopy （SEM）, we measured the short circuit current （Isc）, open circuit voltage （Voc）, and power conversion efficiency （η） of spectral-conversion cells and compared with those of bare solar cells as a reference. Preliminary experimental results revealed that in an optimized PV cell, an enhancement of （0.64＋0.01）% （from 16.03% to 16.67%） in Δη of a Si-based PV cell was achieved.

Utilizing the ultrasensitive Schistosoma up-converting phosphor lateral flow circulating anodic antigen(UCP-LF CAA)assay for sample pooling-strategies

Background:Methodological applications of the high sensitivity genus-specific Schistosoma CAA strip test,allowing detection of single worm active infections(ultimate sensitivity),are discussed for efficient utilization in sample pooling strategies.Besides relevant cost reduction,pooling of samples rather than individual testing can provide valuable data for large scale mapping,surveillance,and monitoring.Method:The laboratory-based CAA strip test utilizes luminescent quantitative up-converting phosphor(UCP)reporter particles and a rapid user-friendly lateral flow(LF)assay format.The test includes a sample preparation step that permits virtually unlimited sample concentration with urine,reaching ultimate sensitivity(single worm detection)at 100%specificity.This facilitates testing large urine pools from many individuals with minimal loss of sensitivity and specificity.The test determines the average CAA level of the individuals in the pool thus indicating overall worm burden and prevalence.When requiring test results at the individual level,smaller pools need to be analysed with the pool-size based on expected prevalence or when unknown,on the average CAA level of a larger group;CAA negative pools do not require individual test results and thus reduce the number of tests.Results:Straightforward pooling strategies indicate that at sub-population level the CAA strip test is an efficient assay for general mapping,identification of hotspots,determination of stratified infection levels,and accurate monitoring of mass drug administrations(MDA).At the individual level,the number of tests can be reduced i.e.in low endemic settings as the pool size can be increased as opposed to prevalence decrease.Conclusions:At the sub-population level,average CAA concentrations determined in urine pools can be an appropriate measure indicating worm burden.Pooling strategies allowing this type of large scale testing are feasible with the various CAA strip test formats and do not affect sensitivity and specificity.It allows cost efficient stratified testing and monitoring of worm burden at the sub-population level,ideally for large-scale surveillance generating hard data for performance of MDA programs and strategic planning when moving towards transmission-stop and elimination.

Up-converted ultraviolet luminescence of Er3＋：BaGd2Zn05phosphors for healthy illumination

Moderate level of exposure to the solar irradiation containing UV component is essential for health care. To incorporate the UV-emitting phosphors into the commercial YAG-based white light-emitting diode introduces the possibilities of healthy illumination to individuals＇ daily lives. 1 mol.% E3＊-doped BaGd2ZnO5（BGZ） particles were synthesized via sol-gel method and efficient up-converted luminescence peaked at 380 nm was detected under 480 nm excitation. The mixed phosphors with varied mass ratio of Er3＋：BGZ and Ce3＋：YAG particles were encapsulated to form LEDs. The study of the LEDs indicated that the introduction of BGZ component favored the enhancement of color-rendering index and the neutralization of the white light emitting. The WLED with the BGZ/YAG ratio of 8：2 was recommendable for its excellent overall white light luminous performances and UV intensity of 84.55 mW/cm2. The UV illumination dose of the WLEDs with mixed YAG and BGZ was controllable by adjusting the ratio, the illumination distance and the illumination time. Er3＋：BGZ phosphors are promising UV- emitting phosphors for healthy indoor illumination.

Visible to ultraviolet up-conversion in a novel rare earth-free up-converting phosphor

A novel up-converting phosphor,Na_xAl_yF_（x＋3y）/CaF2（0.3 〈 x 〈 0.5,0 〈 y 〈 0.1） composite,is prepared by a hydrothermal process at 180°C and an annealing treatment at 500℃.X-ray diffraction（XRD） pattern indicates that Na_xAl_yF_（x＋3y）/CaF_2 is a composite consisting of NaF,Na_3 AlF_6,and CaF_2.The up-conversion luminescence properties of this phosphor are investigated by fluorescence spectrometer.Results show that Na_xAl_yF_（x＋3y）/CaF_2 exhibits visible-to-ultraviolet up-conversion luminescence properties.The emission peaks at 316 and 336 nm are observed when excited by 610 nm,the luminescence lifetime of the emissions is great than 18 ms,and the internal fluorescence quantum yield is 4.2%.Additionally,the luminescent mechanism of this phosphor is also mentioned.

Rapid Detection of Serum Procalcitonin by Immunochromatograghy Technology Based on Freeze-dried Up-conversion Nanoparticles/Antibody Conjugates

Procalcitonin （PCT） is a sensitive and specific biomarker for sepsis diagnosis and widely used as a biomarker to improve the diagnosis of bacterial infections and to guide the antibiotic therapy. In our work, an improved up-converting nanoparticle （UCP） technology based on the immunochromatographic assay （UPT-ICA） was developed for rapid and quantitative detection of PCT. In order to further improve the accuracy, sensitivity and stability of the assay on the basis of our previous study, the UCP coupling with rnonoclonal antibody of PCT （UCP-Abl） was freeze-dried under certain conditions. And the detections of PCT levels with UCP-Abl conjugates before and after freeze-drying were evaluated. The results show that, compared to the UCP-Abl conjugates without freeze-drying, the detection sensitivity of freeze-dried UCP-Abl is slightly improved, having a lower immunochromatogragh background and better stability. This improved method can provide a rapid, accurate, and relatively easy way for the clinical detection of PCT.

Comparison of novel and standard diagnostic tools for the detection of Schistosoma mekongi infection in Lao People’s Democratic Republic and Cambodia

Background:Given the restricted distribution of Schistosoma mekongi in one province in Lao People’s Democratic Republic(Lao PDR)and two provinces in Cambodia,together with progress of the national control programmes aimed at reducing morbidity and infection prevalence,the elimination of schistosomiasis mekongi seems feasible.However,sensitive diagnostic tools will be required to determine whether elimination has been achieved.We compared several standard and novel diagnostic tools in S.mekongi-endemic areas.Methods:The prevalence and infection intensity of S.mekongi were evaluated in 377 study participants from four villages in the endemic areas in Lao PDR and Cambodia using Kato-Katz stool examination,antibody detection based on an enzyme-linked immunosorbent assay(ELISA)and schistosome circulating antigen detection by lateral-flow tests.Two highly sensitive test systems for the detection of cathodic and anodic circulating antigens(CCA,CAA)in urine and serum were utilized.Results:Stool microscopy revealed an overall prevalence of S.mekongi of 6.4%(one case in Cambodia and 23 cases in Lao PDR),while that of Opisthorchis viverrini,hookworm,Trichuris trichiura,Ascaris lumbricoides and Taenia spp.were 50.4%,28.1%,3.5%,0.3%and 1.9%,respectively.In the urine samples,the tests for CCA and CAA detected S.mekongi infections in 21.0%and 38.7%of the study participants,respectively.In the serum samples,the CAA assay revealed a prevalence of 32.4%,while a combination of the CAA assay in serum and in urine revealed a prevalence of 43.2%.There was a difference between the two study locations with a higher prevalence reached in the samples from Lao PDR.Conclusions:The CCA,CAA and ELISA results showed substantially higher prevalence estimates for S.mekongi compared to Kato-Katz thick smears.Active schistosomiasis mekongi in Lao PDR and Cambodia might thus have been considerably underestimated previously.Hence,sustained control efforts are still needed to break transmission of S.mekongi.The pivotal role of highly sensitive diagnostic assays in areas targeting elimination cannot be overemphasised.