The CDEX-1 1 kg Point-Contact Germanium Detector for Low Mass Dark Matter Searches

The CDEX Collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold p-type point-contact germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact p+ electrode and the outside n+ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both p+ and n+ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments.Comment: 6 pages, 8 figure

An oligonucleotide microarray for microRNA expression analysis based on labeling RNA with quantum dot and nanogold probe

MicroRNAs (miRNAs) play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. They have diverse expression patterns and might regulate various developmental and physiological processes. Profiling miRNA expression is very helpful for studying biological functions of miRNAs. We report a novel miRNA profiling microarray, in which miRNAs were directly labeled at the 3′ terminus with biotin and hybridized with complementary oligo-DNA probes immobilized on glass slides, and subsequently detected by measuring fluorescence of quantum dots labeled with streptavidin bound to miRNAs through streptavidin–biotin interaction. The detection limit of this microarray for miRNA was ∼0.4 fmol, and the detection dynamic range spanned about 2 orders of magnitude. We made a model microarray to profile 11 miRNAs from leaf and root of rice (Oryza sativa L. ssp. indica) seedlings. The analysis results of the miRNAs had a good reproducibility and were consistent with the northern blot result. To avoid using high-cost detection equipment, colorimetric detection, a method based on nanogold probe coupled with silver enhancement, was also successfully introduced into miRNA profiling microarray detection

Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials

Observational studies have indicated that soya food consumption is inversely associated with blood pressure (BP). Evidence from randomised controlled trials (RCT) on the BP-lowering effects of soya protein intake is inconclusive. We aimed to evaluate the effectiveness of soya protein intake in lowering BP. The PubMed database was searched for published RCT in the English language through to April 2010, which compared a soya protein diet with a control diet. We conducted a random-effects meta-analysis to examine the effects of soya protein on BP. Subgroup and meta-regression analyses were performed to explore possible explanations for heterogeneity among trials. Meta-analyses of twenty-seven RCT showed a mean decrease of 2·21 mmHg (95 % CI - 4·10, - 0·33; P = 0·021) for systolic BP (SBP) and 1·44 mmHg (95 % CI - 2·56, - 0·31; P = 0·012) for diastolic BP (DBP), comparing the participants in the soya protein group with those in the control group. Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet. Meta-regression analyses further revealed a significantly inverse association between pre-treatment BP and the level of BP reductions. In conclusion, soya protein intake, compared with a control diet, significantly reduces both SBP and DBP, but the BP reductions are related to pre-treatment BP levels of subjects and the type of control diet used as comparison

Comparative and functional genomics reveals genetic diversity and determinants of host specificity among reference strains and a large collection of Chinese isolates of the phytopathogen Xanthomonas campestris pv. campestris

Construction of a microarray based on the genome of Xanthomonas campestris pv.campestris (Xcc), and its use to analyse 18 other virulent Xcc strains, revealed insights into the genetic diversity and determinants of host specificity of Xcc strains

Development of an Aerodynamic Lens-Proton Transfer Reaction Mass Spectrometry (PTR-MS) Apparatus for Online Detection of Organic Compounds in Aerosol Particles

Atmospheric organic aerosols consist of both gas-phase organic compounds and particle-phase organic compounds. The components of aerosol particles (solid or liquid droplets) can undergo exchange or chemical reactions with gas-phase components, influencing atmospheric physical and chemical processes and potentially impacting atmospheric environment, climate, and human health. Methods for detecting organic compounds in aerosol particle phase are classified into offline and online detection. Offline detection methods involve collecting aerosol samples for analysis using chromatography-mass spectrometry, which is time-consuming and limited sensitivity. Online detection methods involve enriching aerosols through aerodynamic lens and then detecting them using laser ablation or electron impact ionization techniques. However, these methods usually generate a large number of ion fragments, making mass spectrum analysis difficult. Therefore, it is necessary to develop an online detection method for aerosol particle-phase organic compounds with soft ionization and high sampling efficiency. In the present work, a set of aerodynamic lens sampling systems was designed and developed for online detection and analysis of organic compounds in aerosol particle phase. This sampling system consists of a gas-phase stripping module for removing gas-phase organic compounds, an aerodynamic lens module for particle focusing and enrichment, and a thermal desorption module for extracting particle-phase organic compounds. The efficiency of gas-phase organic compound removal and the particle transmission rate of the gas-phase stripping module were firstly investigated. The results showed that gas-phase stripping module achieves a removal efficiency of 98.89% for gas-phase organic compounds, and the particle transmission rate ranges from 75.16% to 91.15% for particles with the diameters between 295 and 375 nm. Subsequently, the effectiveness of the aerodynamic lens was studied through theoretical simulations. The simulation results indicated that the transmission rate of particles in the diameters of 0.36-6.0 μm is above 90% in the designed aerodynamic lens. Finally, The designed aerodynamic lens sampling system with a homemade proton transfer reaction mass spectrometer (PTR-MS) was integrated to develop an aerodynamic lens-PTR-MS device. This device was tested by detecting simulated aerosol samples containing reaction products of α-pinene and ozone. The mass spectrometry results demonstrated that the intensity changes of the examined ten ions are closely related to the presence of α-pinene, confirming that the device can achieve online detection of organic compounds in aerosols ranging from submicron to several micrometers