Achieving highly-efficient H2S gas sensor by flower-like SnO_(2)–SnO/porous GaN heterojunction

A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical wet etching of GaN,and SnO_(2)–SnO composites with p–n junctions were loaded onto PGaN surface directly applied to H_(2)S sensor. Meanwhile,the excellent transport capability of heterojunction between FSS and PGaN facilitates electron transfer, that is, a response time as short as 65 s and a release time up to 27 s can be achieved merely at 150℃ under 50 ppm H_(2)S concentration, which has laid a reasonable theoretical and experimental foundation for the subsequent PGaN-based heterojunction gas sensor.The lowering working temperature and high sensitivity(23.5 at 200 ppm H2S) are attributed to the structure of PGaN itself and the heterojunction between SnO_(2)–SnO and PGaN. In addition, the as-obtained sensor showed ultra-high test stability.The simple design strategy of FSS/PGaN-based H_(2)S sensor highlights its potential in various applications.

Pathways of meridional atmospheric moisture transport in the central Arctic

Atmospheric moisture transport plays an important role in latent heat release and hydrologic interactions in the Arctic.In recent years,with the rapid decline in sea ice,this transport has changed.Here,we calculated the vertically integrated atmospheric moisture meridional transport(AMTv)from two global reanalysis datasets,from1979–2015,and found moisture pathways into the central Arctic.Four stable pathways showed an occurrence frequency greater than 70%,and these pathways exhibited a perennial seasonal pattern in the atmosphere above the Laptev Sea Pathway(LSP),Canadian Arctic Archipelago Pathway(CAAP),both sides of the Greenland plateau.Another seasonal pathway appeared above the east of the Chukchi Sea(CSP)during the melting/freezing months(March to September).Through these pathways,AMTv contributed a total moisture exchange of60%–80%—averaged over a 75°N circle—and focused on the low troposphere.Transports across the LSP,CSP and CAAP pathways likely create an enclosed moisture route.Meridional moisture fluxes are intensified in the Pacific sector of Arctic(PSA),especially during melting/freezing months.AMTv interannual variabilities are illustrated mainly in the Laptev Sea and the east Greenland pathway.Results indicate that accompanying a tendency for a stronger Beaufort Sea High in this sea level pressure field,AMTv through PSA pathways,switched from output to input,and approximately 960 km^3 of equivalent liquid water was transferred into the central Arctic during each decade.The detrended AMTv increment is highly correlated with the rapid decline of old ice areas(correlation coefficient is–0.78)for their synchronous fluctuations in the 1980 s and the last decade.

Structure and Formative Mechanism of Black Patina on Bronze Mirrors

The formation of the black patina induced by soil humic asid under different conditions was studied, theblack, grey and brown colored shiny surfaces prepared in laboratory were analyzed. As a result the formation oftin-rich shiny black surface on bronze mirrors is the product of soil corrosion of the bronze mirrors. The patina isformed by reection between the alloy and the humic acid in soil, and leaching of copper and lead oxides through along period time when the mirrors were buried under the ground leaving a dense compact corrosion-resistant layerconsisted predominantly of stannic oxide microcrystal.

Regional Sea Level Variation on Interannual Timescale in the East China Sea

Interannual sea level variation is investigated with the oceanic and atmospheric datasets in the East China Sea (ECS). Two modes are distinct on the interannual timescale, illustrated as the basin mode and the dipole mode. They account for 20% and 18% to the total interannual sea level variance respectively. The basin mode corresponds to the variability of the Kuroshio transport which is modulated by the PDO while the dipole mode is likely related to the local oceanic and atmospheric adjustment. Large-scale atmospheric circulation effect is dominant in influencing the interannual sea level in the ECS. ECS sea level responds barotropically to the basin-wide wind field, which illustrates negative correlation to the zonal-mean wind stress curl in the Pacific Ocean. Sea level variation exhibits the negative correlation at 8 years lag with the basin mean wind stress curl anomalies on the interannual timescale. The lagging years are consistent with the timescale that the baroclinic Rossby waves propagate westward in the North Pacific Ocean. Wind stress curl anomalies could also change the strength of the Kuroshio transport, and thus affect the local sea level through sea surface height adjustment. Local oceanic and atmospheric effect illustrates as another influence process. Steric effect contributes more than 20% to the interannual sea level gradually in a belt from the Fujian and Zhejiang coasts to the Korea/Tsushima strait. Especially in the northeast part, its contribution could be up to 60%. While for the local atmospheric process, zonal wind acts as a more important role on sea level than meridional component.

A Digital Background Calibration Technique for Successive Approximation Register Analog-to-Digital Converter

A digital background calibration technique that corrects the capacitor mismatches error is proposed for successive approximation register analog-to-digital converter (SAR ADC). The technique is implemented in SAR ADC which is based on tri-level switching. The termination capacitor in the Digital-to-Analog Converter (DAC) is regarded as a reference capacitor and the digital weights of all other unit capacitors are corrected with respect to the reference capacitor. To make a comparison between the size of the unit capacitor and that of the reference capacitor, each input sample is quantized twice. The unit capacitor being calibrated is swapped with the reference capacitor during the second conversion. The difference between the two conversion results is used to correct the digital weight of the unit capacitor under calibration. The calibration technique with two reference capacitors is presented to reduce the number of parameters to be estimated. Behavior simulation is performed to verify the proposed calibration technique by using a 12-bit SAR ADC with 3% random capacitor mismatch. The simulation results show that the Signal-to-Noise and Distortion Ratio (SNDR) is improved from 57.2 dB to 72.2 dB and the Spurious Free Dynamic Range (SFDR) is improved from 60.0 dB to 85.4 dB.

Sequence analysis of the hsp60 gene and it′s application in identification of pathogenic bacteria

To support the scientific basis for rapid identification of pathogenic bacteria and other stud- ies,the sequences of hsp60 gene in major 34 species of 16 genus of pathogenic bacteria were search out in GenBank and a proper pair of universal degenerate primer was designed by means of the molecu- lar biological softwawe Primer 5.0 and Oligo 6.0.This primer was then used in the PCR amplification, and the hsp60 gene fragments of the selected pathogenic bacteria could be amplified using this degener- ate primer.By way of bioinformational analysis,the conservation,variation and the interspecies phylo- genetic relations of the hsp60 gene sequence were analysed.From the results of the comparative study on sequences,it was demonstrated that the hsp60 gene was characterized by conservation and varia- tion,in which the conserved and mutant regions co-existed and separately distributed with many small mutant regions distributed among the conserved regions,just like the mosaic.The phylogenetic tree among different pathogenic bacteria drawn from the hsp60 gene analysis was proved to be consistent with those from 16S rRNA and 23S rRNA.It is concluded that the sequence distribution of hsp60 gene would provide a solid basis for the rapid identification of pathogenic bacteria and the development of a diagnostic microarray.

Multifactorial role of HIV-Vpr in cell apoptosis revealed by a naturally truncated 54aa variant

Although antiretroviral therapy(ART)is effective at suppressing the human immunodeficiency virus type 1(HIV-1)replication,HIV-1 infection is still a global public health problem.HIV-1 accessory protein viral protein R(Vpr)is a multifunctional protein with a primary role in regulating cellular apoptosis.[1]The amino acid(aa)positions 52-96 in the C-terminus of Vpr were identified as the apoptosis-regulating domain.[2,3]In this study,we found a natural Vpr variant truncated at the 54 aa position(*54Vpr)from HIV patients in the acquired immune deficiency syndrome(AIDS)phase that mediated both pro-and antiapoptotic cellular effects by interacting with distinct adenine nucleotide translocator(ANT)isoforms.A novel apoptosis-regulating domain was further identified in the 23-37 aa position in the N-terminus of Vpr.

A new encryption scheme for surveillance videos

In this paper, we propose a novel framework to encrypt surveillance videos. Although a few encryption schemes have been proposed in the literature, they are not sufficiently efficient due to the lack of full consideration of the characteristics of surveillance videos, i.e., intensive global redundancy. By taking advantage of such redundancy, we design a novel method for encrypting such videos. We first train a background dictionary based on several frame observations. Then every single frame is parsed into the background and foreground components. Separation is the key to improve the efficiency of the proposed technique, since encryption is only carried out in the foreground, while the background is skillfully recorded by corresponding background recovery coefficients. Experimental results demonstrate that, compared to the state of the art, the proposed method is robust to known cryptanalytic attacks, and enhances the overall security due to the foreground and background separation. Additionally, our encryption method is faster than competing methods, which do not conduct foreground extraction.