High performance solar-blind UV detector with Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer structure on MgO substrate.

Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer structure UV detectors are made on single structure MgO substrate by PLD method, and the effect of different thickness top MgZnO layer on the UV response characteristics of the detector are studied. Compared with the single layer MgZnO detector that made by Mg0.3Zn0.7O target, the Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer detector with 30 nm top layer, shows much higher deep UV response (21.3 A W-1at 265 nm), much smaller dark current(66.9 pA) and much higher signal-to-noise ratio (2.8 × 105) at 25 V bias voltage. And the device also shows relative high response (23.1 A W-1) at 235 nm deep UV light at 25 V bias voltage, which is mainly attributed by the bottom MgZnO layer with higher Mg composition. When the top layer is 66.7 nm thick, the response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector reached 228.8 A W-1at 255 nm under 25 V bias voltage, the signal-to-noise ratio of which is 10573 under 20 V bias voltage, and the near UV response of the device is also big because of more h-MgZnO in top MgZnO layer. When the top layer reached 90.2 nm, there are much more h-MgZnO in the top MgZnO layer, the peak response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector is just 6.65 A W-1at 320 nm under 25 V bias voltage, the signal-to-noise ratio of which is 1248. The high Mg composition bottom MgZnO decrease the dark current of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector, both the 2DEG effect of the double layer structure and the amplify effect of the mix-phase MgZnO top layer, increased theIuvand deep UV response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector. Therefore, the double layer Mg0.472Zn0.528O/Mg0.447Zn0.553O detector is more sensitive at faint deep UV light compared with previous reported MgZnO detectors, and the MgxZn1-xO/MgyZn1-yO detector shows similarIuvand signal-noise-ratio at faint deep UV light as high-temperature fabricated AlxGa1-xN/AlyGa1-yN detectors.

Microscale heterogeneity of the soil nitrogen cycling microbial functional structure and potential metabolism.

Soil aggregates, with complex spatial and nutritional heterogeneity, are clearly important for regulating microbial community ecology and biogeochemistry in soils. However, how the taxonomic composition and functional attributes of N-cycling-microbes within different soil particle-size fractions under a long-term fertilization treatment remains largely unknown. Here, we examined the composition and metabolic potential for urease activity, nitrification, N2 O production and reduction of the microbial communities attached to different sized soil particles (2000-250, 250-53 and <53 µm) using a functional gene microarray (GeoChip) and functional assays. We found that urease activity and nitrification were higher in <53 µm fractions, whereas N2 O production and reduction rates were greater in 2000-250 and 250-53 µm across different fertilizer regimes. The abundance of key N-cycling genes involved in anammox, ammonification, assimilatory and dissimilatory N reduction, denitrification, nitrification and N2 -fixation detected by GeoChip increased as soil aggregate size decreased; and the particular key genes abundance (e.g., ureC, amoA, narG, nirS/K) and their corresponding activity were uncoupled. Aggregate fraction exerted significant impacts on N-cycling microbial taxonomic composition, which was significantly shaped by soil nutrition. Taken together, these findings indicate the important roles of soil aggregates in differentiating N-cycling metabolic potential and taxonomic composition, and provide empirical evidence that nitrogen metabolism potential and community are uncoupled due to aggregate heterogeneity.

Flexible non-linear physical security coding scheme combined with chaotic neural network for OFDM-WDM-PON.

In this paper, a flexible physical security coding scheme integrating chaotic neural network (CNN) and non-linear encryption is proposed for orthogonal frequency division multiplexing wavelength division multiplexing passive optical network (OFDM-WDM-PON). The scheme improved the flexibility, adjustability and the key space of chaotic encryption system by introducing chaos into neural networks. The system will encrypt the bit series, probability shaping points, and subcarriers position of the OFDM signal through linear encryption and non-linear encryption concurrently. Results show that a key sensitivity of 10-15 and a key space of more than 10279 can be achieved. The encrypted system's Lyapunov is 5.2631, along with 12 parameters can be dynamically changed in the range of 0∼5. Furthermore, when the bit error rate (BER) is less than 3.8×10-3, probabilistic shaping (PS) technology decreases power loss by around 0.5 dB. A 20.454 Gb/s data transmission experiment was successfully verified for a span of 25 Km single-mode fiber. According to the experimental results, the proposed encryption scheme is likely to be used in future OFDM-WDM-PON transmission systems.

Multiple Stokes sectional plane image based modulation format recognition with a generative adversarial network.

A novel modulation format recognition (MFR) scheme based on multiple Stokes sectional planes images by generative adversarial network (GAN) is proposed and demonstrated to adapt to next-generation elastic optical network (EON). The application of the encoder, along with the suitable loss function, is able to achieve better performance with regards to MFR of GAN. Experimental verifications were performed for the polarization division multiplexing (PDM)-EON system at a symbol rate of 12.5GBaud. Five modulation formats, including PDM-BPSK, PDM-QPSK, PDM-8PSK, PDM-8QAM, PDM-16QAM, were recognized by our scheme under the condition of practical optical signal-to-noise ratio (OSNR) over both back-to-back transmission and 25km standard signal-mode fiber (SSMF). Specifically, the minimum required OSNR of PDM-16QAM signal to achieve 100% MFR success rate is 18 dB, which is lower than its corresponding 7% forward error correction (FEC) threshold. Results show that, compared with three other machine learning algorithms, the proposed scheme obtains the higher recognition accuracy in the case of the same OSNR. Moreover, the training data required by the proposed scheme is less than the traditional convolutional neural network (CNN) in MFR task, which means the training cost of the neural network is greatly reduced by using GAN.

UV response characteristics of mixed-phase MgZnO thin films with different structure distributions, high Iuv/Idark ratios, and fast speed MgZnO UV detectors with tunneling breakdown mechanisms.

High-performance ultraviolet (UV) detectors with both high responses and fast speeds are hard to make on homogeneous crystal semiconductor materials. Here, the UV response characteristics of mixed-phase MgZnO thin films with different internal structure distributions are studied. The mixed-phase MgZnO-based detector with the given crystal composition has a high response at both deep UV light (96 A W-1 at 240 nm) and near UV light (80 A W-1 at 335 nm). Meanwhile, because of the quasi-tunneling breakdown mechanism within the device, the high-response UV detector also shows a fast response speed (tr = 0.11 µs) and recovery speed (td1 = 26 µs) at deep UV light, which is much faster than both low-response mixed-phase MgZnO-based UV detectors with other structure constitutions and reported high-response UV devices on homogenous crystal materials. The Idark of the device is just 4.27 pA under a 5 V bias voltage, so the signal-to-noise ratio of the device reached 23852 at 5.5 uW cm-2 235 nm UV light. The new quasi-tunneling breakdown mechanism is observed in some mixed-phase MgZnO thin films that contain both c-MgZnO and h-MgZnO parts, which introduce a high response, signal-to-noise ratio, and fast speed into mixed-phase MgZnO-based UV detectors at weak deep UV light.

UV response characteristics of mixed-phase MgZnO thin films with different structure distribution and high Iuv/Idarkratio and fast speed MgZnO UV detector with tunneling breakdown mechanism.

High performance UV detector with both high response and fast speed is hard to made on homogeneous crystal semiconductor materials. Here, the UV response characteristics of mix-phase MgZnO thin films with different internal structure distribution are studied, the mix-phase MgZnO based detector with given crystal composition own high response at both deep UV light (96 A/W at 240nm) and near UV light (80 A/W at 335nm). Meanwhile, because of quasi-tunneling breakdown mechanism within the device, the high response UV detector also show fast response speed (tr= 0.11 µs) and recovery speed (td1=26 µs) at deep UV light, which are much faster than the both low response mix-phase MgZnO based UV detectors with other structure constitution and reported high response UV devices on homogenous crystal materials. The Idarkof the device is just 4.27 pA under a 5 V bias voltage, so the signal to noise ratio of the device reached 23852 at 5.5uW/cm2 235nm UV light. Therefore, new quasi-tunneling breakdown mechanism is observed in some mix-phase MgZnO thin film that contains both c-MgZnO and h-MgZnO parts, which introduced high response, signal to noise ratio and fast speed into mix-phase MgZnO based UV detector at weak deep UV light.

Enhanced 3D-CAP modulation with information-inserted time slots for seven-core fiber transmissions.

An enhanced three-dimensional carrier-less amplitude phase (3D-CAP) modulation with information-inserted time slots is proposed in this paper. Compared with the traditional 3D-CAP, the proposed scheme can reduce the value of the up-sampling factor by loading information on the time slots position, thus achieving better bit error rate (BER) performance under the same bit rate. An experiment demonstrating 43.75 Gb/s MIMO-free transmission employing the proposed enhanced 3D-CAP modulation over 2 km weakly coupled 7-core fiber is successfully carried out. The experimental results show that the difference between the best and worst core is about 1.7 dB in receiver sensitivity at a BER of 1 × 10-3 due to the geometrical reason, and the proposed scheme outperforms the traditional 3D-CAP-16 by 2.7 dB in core-1.

High security OFDM-PON with a physical layer encryption based on 4D-hyperchaos and dimension coordination optimization.

In this article we have enhanced the security of an orthogonal frequency division multiplexed passive optical network (OFDM-PON) based on four dimensional (4D) encryption, including constellation, subcarrier, symbol and time, which is proposed for the first time in this paper. 4D-hyperchaotic mapping is used to generate four masking factors to achieve ultra-high security encryption in four different dimensions. During the encryption, dimension coordination optimization is adopted, which effectively reduces the time cost of the system and improves the encryption efficiency by 3 times. At the same time, probabilistic shaping (PS) technology is used to further optimize the system that has effectively improved the bit error performance by about 1 dB. The proposed encryption technique for OFDM-PON has been demonstrated successfully with the help of experiments. The generated OFDM signal is modulated by the quadrature amplitude modulation (QAM) technique, which transmitted 16 Gb/s data rate across a 25 km fiber span of standard single-mode fiber. The values of bit error rate (BER) and peak-to-average-power ratio (PAPR) are analyzed during the experiments, and the obtained results show that the proposed security-enhanced OFDM-PON has high sensitivity and security and can be well compatible with PS and OFDM technologies. The proposed scheme has very reliable security performance and also has excellent benefit improvement, which is very promising in the future PS-OFDM-PON.

Chaotic constant composition distribution matching for physical layer security in a PS-OFDM-PON.

This paper proposes a probabilistic shaping orthogonal frequency division multiplexing passive optical network (PS-OFDM-PON) based on chaotic constant composition distribution matching (CCDM). With the implementation of a four-dimensional hyperchaotic Lv system, probabilistic shaping and chaotic encryption are realized with low complexity on the process of signal modulation, so as to enhance the system performance in the presence of bit error rate (BER) and security. An 8.9 Gb/s encrypted PS-16 quadrature amplitude modulation (QAM)-OFDM signal transmission over a 25 km standard single mode fiber (SSMF) is experimentally demonstrated. And experimental results indicate that compared with conventional uniform 16QAM-OFDM, the encrypted PS-16QAM-OFDM can obtain a 1.2 dB gain in receiver sensitivity at a BER of 10-3 under the same bit rate. Moreover, the key space of the proposed scheme is 1.98 × 1073, which is a large enough number to effectively guard against any malicious attacks from illegal optical network units (ONUs). The combined superiority of BER and security performance enables a promising prospect for the proposed PS chaotic encryption scheme in a future low-cost optical access network.

Security-enhanced OFDM-PON with two-level coordinated encryption strategy at the bit-level and symbol-level.

A novel security-enhanced scheme combining improved deoxyribonucleic acid (DNA) encoding encryption at the bit-level with matrix scrambling at the symbol-level is proposed in OFDM-PON for the first time in this paper. In our proposed scheme, firstly each subcarrier is encrypted by improved DNA encoding encryption, which includes the functioning of key base series and the cross interchange. And the selected encoding rules, decoding rules, key base series, operating principles and the positions of cross interchange are dynamically changing, which enhances the robustness against malicious attacks by illegal attackers. Then during the matrix scrambling process, the non-equal-length quadrature amplitude modulation (QAM) matrix is divided into several squares of equal length according to an optimum method. At the same time, the times of matrix scrambling can be determined randomly. With the multi-fold encryption of the proposed scheme, the achieved key space can reach up to 10154, which can sufficiently ensure the physical layer security. Experimental verification of the proposed security-enhanced strategy was demonstrated in an 8 Gb/s 16QAM orthogonal frequency division multiplexing passive optical network (OFDM-PON) system over 25-km standard single-mode fiber (SSMF). The experimental results prove that the two-level coordinated encryption at the bit-level and symbol-level using chaos and encryption can effectively protect data from violent attacks, differential attacks, etc.

5D data iteration in a multi-wavelength OFDM-PON using the hyperchaotic system.

In this Letter, a novel five-dimensional (5D) data-iteration-based encryption model is proposed at physical layer for multi-wavelength optical frequency division multiplexing passive optical network (OFDM-PON) by using a hyperchaotic system. The proposed scheme can generate five chaotic sequences at a time. The sensitivity of 10-18 can be achieved, along with a key space of 1095. In addition, we use a multi-wavelength channel to transmit the information, and the optical network unit can freely choose the wavelength. The probability shaping technology has greatly improved the bit error rate performance. A 16Gb/s/λ data is successfully transmitted across 25 km standard single-mode fiber in the experimental verifications. Therefore, it will have a positive impact in the future security optical network.

Effect of Different Clarification Treatments on the Volatile Composition and Aromatic Attributes of 'Italian Riesling' Icewine.

The aim of this study was to evaluate the influence of clarification treatments on volatile composition and aromatic attributes of wine samples. 'Italian Riesling' icewines from the Hexi Corridor Region of China were clarified by fining agents (bentonite (BT) and soybean protein (SP)), membrane filtration (MF), and centrifugation (CF) methods. The clarity, physicochemical indexes, volatile components, and aromatic attributes of treated wines were investigated. Both the fining agents and mechanical clarification treatments increased the transmittance and decreased the color intensity of icewine samples. Bentonite fining significantly influenced the total sugar content, total acidity and volatile acidity. Total acidity decreased 2-3.5% and volatile acidity 2-12%. MF showed the greatest influence on total phenol content, decreasing the initial content by 12%, while other treatments by less than 8%. Volatile analysis indicated that both the categories and contents of volatile compounds of wine samples decreased. MF treatment showed the most significant influence, while SP fining showed much lower impact. Odor activity values indicated the compound with the highest odor activity in Italian Riesling icewines was ß-damascenone. For this compound, BT and SP did not show significant differences, however, in MF and CF it decreased by 20% and 63%, respectively. Furthermore, with high impact on aroma were: ethyl hexanoate which reduced by 20-80% especially in MF; rose oxide which extremely reduced in MF and undetected in BT, SP, and CF; isoamyl acetate which reduced by 3-33% and linalool decreased by 10-20% and undetected for BT. Principle component analysis indicated that icewine clarified by different methods could be distinguished and positively correlated with odor-active compounds. Floral and fruity were the dominant aroma series in icewine samples followed by fatty, earthy, spicy, vegetative and pungent flavor. The total odor active value of these series significantly (p < 0.5) decreased in different clarification treatments. Sensory evaluation showed similar results, but the SP and CF wine samples achieved better sensory quality. This study provides information that could help to optimize the clarification of ice wines.

Fast Response Solar-Blind Photodetector with a Quasi-Zener Tunneling Effect Based on Amorphous In-Doped Ga2O3 Thin Films.

A high-performance solar-blind photodetector with a metal-semiconductor-metal structure was fabricated based on amorphous In-doped Ga2O3 thin films prepared at room temperature by radio frequency magnetron sputtering. The photodetector shows a high responsivity (18.06 A/W) at 235 nm with a fast rise time (4.9 µs) and a rapid decay time (230 µs). The detection range was broadened compared with an individual Ga2O3 photodetector because of In doping. In addition, the uneven In distribution at different areas in the film results in different resistances, which causes a quasi-Zener tunneling internal gain mechanism. The quasi-Zener tunneling internal gain mechanism has a positive impact on the fast response speed and high responsivity.

Simultaneous Analysis of 20 Mycotoxins in Grapes and Wines from Hexi Corridor Region (China): Based on a QuEChERS⁻UHPLC⁻MS/MS Method.

The aim of this study is to develop and validate an improved analytical method for the simultaneous quantification of 20 types of mycotoxins in grapes and wines. In this research, the optimization of tandem mass spectrometer (MS/MS) parameter, ultra-high pressure liquid chromatography (UHPLC) separation, and QuEChERS procedure, which includes wine/water ratio, the amount and type of salt, clean-up sorbent, were performed, and the whole separation of mycotoxins was accomplished within 7 min analyzing time. Under optimum conditions, recoveries ranged from 85.6% to 117.8%, while relative standard deviation (RSD) remained between 6.0% and 17.5%. The limit of detection (LOD, 0.06⁻10 µg/L) and the limit of quantification (LOQ, 0.18⁻30 µg/L) were lower than those permitted by legislation in food matrices, which demonstrated the high sensitivity and applicability of this efficient method. Finally, 36 grapes and 42 wine samples from the Hexi Corridor region were analyzed. Penicillic acid (PCA), mycophenolic acid (MPA), cyclopiazonic acid (CPA), fumonisin B1 (FB1) and zearalenone (ZEN) were detected in a small number of grape samples with lower concentrations between 0.10 µg/L and 81.26 µg/L. Meanwhile, ochratoxin A (OTA), aflatoxin B2 (AFB2), MPA, CPA, and ZEN were detected in some wine counterparts with concentrations ranged from 0.10 µg/L to 4.62 µg/L. However, the concentrations of the detected mycotoxins were much lower than the maximum legal limits set of other products.

[Preparation and in vitro evaluation of arsenic trioxide glioma targeting drug delivery system loaded by PAMAM dendrimers co-modified with RGDyC and PEG].

Arsenic trioxide (ATO) is an effective component of traditional Chinese medicine arsenic. The existing studies have shown its good inhibition and apoptosis ability on a variety of tumours. However, its toxicity and difficulties in the permeability into the blood brain barrier (BBB) has the limitation in the application of glioma treatment. Polyamide-amine dendrimer (PAMAM) is a synthetic polymer with many advantages, such as a good permeability, stability and biocompatibility. Additionally, the 5th generation of PAMAM is an ideal drug carrier due to its three-dimensional structure. In this study, the 5th generation of PAMAM co-modified with RGDyC and PEG, then confirmed by ¹H-NMR. The average particle size of nanoparticles was about 20 nm according to the nanoparticle size-potential analyser and transmission electron microscopy. in vitro release showed that the nanocarrier not only has the sustained release effect, but also some pH-sensitive properties. The cell results showed that PAMAM co-modified with RGDyC and PEGAM has a lower cytotoxicity than the non-modified group in vitro. Accordingly, the drug delivery system has a better anti-tumour effect across the blood brain barrier (BBB) in vitro, which further proves the tumour targeting of RGDyC.

Long-term straw returning affects Nitrospira-like nitrite oxidizing bacterial community in a rapeseed-rice rotation soil.

Nitrospira are the most widespread and well known nitrite-oxidizing bacteria (NOB) and putatively key nitrite-oxidizers in acidic ecosystems. Nevertheless, their ecology in agriculture soils has not been well studied. To understand the impact of straw incorporation on soil Nitrospira-like bacterial community, a cloned library analysis of the nitrite oxidoreductase gene-nxrB was performed for a long-term rapeseed-rice rotation system. In this study, most members of the Nitrospira-like NOB in the paddy soils from the Wuxue field experiment station were phylogenetically related with Nitrospira lineages II. The Shannon diversity index possessed a decrease trend in the straw applied soils. The relative abundances of 16 OTUs (accounting 72% of the total OTUs, including 11 unique OTUs and 5 shared OTUs) were different between in the straw applied and control soils. These data suggested a selection effect from the long-term straw fertilization. Canonical correspondence analysis data showed that a centralized group of Nitrospira-like NOB OTUs in the community was partly explained by the soil ammonium, nitrate, available phosphorus, and the available potassium. This could suggest that straw fertilization led to the soil Nitrospira-like NOB community shift, which was correlated with the change of available nutrients in the bulk soil.

[Comparison of Postmortem MSCT and Autopsy Findings in Traffic Accident Victims].

OBJECTIVE: To explore the application value of postmortem multi-slice spiral computed tomography (MSCT) by observing and analyzing the injury features in the traffic accident victims. METHODS: Ten traffic accident victims were scanned with whole body MSCT. The systemic autopsy was subsequently performed to compare with the results of MSCT. The advantages and disadvantages of autopsy and MSCT for obtaining the information of traffic accident injuries were then analyzed. RESULTS: MSCT could reveal 3D shape of fractures clearly and detect air accumulation in different positions of the body, which showed the obvious advantages compared with autopsy. However, the resolution of MSCT was limited compared to the detection of organ and soft tissue injuries. CONCLUSION: A combination of MSCT and autopsy is the best way for determining the manner and the cause of death in traffic fatality victims.

[Preparation and in vitro evaluation of borneol and folic acid co-modified doxorubicin loaded PAMAM drug delivery system].

A novel targeting drug carrier (FA-BO-PAMAM) based on the PAMAM G5 dendrimer modified with borneol (BO) and folic acid (FA) molecules on the periphery and doxorubicin (DOX) loaded in the interior was designed and prepared to achieve the purposes of enhancing the blood-brain barrier (BBB) transportation and improving the drug accumulation in the glioma cells. 1H NMR was used to confirm the synthesis of FA-BO-PAMAM; its morphology and mean size were analyzed by dynamic light scattering (DLS) and transmission electron microscope (TEM). Based on the HBMEC and C6 cells, cytotoxicity assay, transport across the BBB, cellular uptake and anti-tumor activity in vitro were investigated to evaluate the properties of nanocarriers in vitro. The results showed that the nanocarrier of FA-BO-PAMAM was successfully synthesized, which was spherical in morphology with the average size of (22.28 ± 0.42) nm, and zeta potential of (7.6 ± 0.89) mV. Cytotoxicity and transport across the BBB assay showed that BO-modified conjugates decreased the cytotoxicity of PAMAM against both HBMEC and C6 cells and exhibited higher BBB transportation ability than BO-unmodified conjugates; moreover, modification with FA increased the total uptake of DOX by C6 cells and enhanced the cytotoxicity of DOX-polymer against C6 cells. Therefore, FA-BO-PAMAM is a promising nanodrug delivery system in employing PAMAM as a drug carrier and treatment for brain glioma.

[Postmortem MSCT Analysis and Identification of Fall from Height: One Case Report].

OBJECTIVE: To explore the application value of postmortem multi-slice spiral computed tomography (MSCT) in cases of fall from height through observing and analyzing the injury features of the fall and reconstructing the process of the fall based on the the above procedure. METHODS: One real fatal case due to fall from height was fully examined using MSCT and three-dimensional reconstruction technique. Analyzing the manner and cause of death through combination of MSCT and systemic autopsy was also implemented. The differences between autopsy and MSCT in getting information of injuries were compared. RESULTS: Fractures involving multiple body regions and liver rupture were found through MSCT and three-dimensional reconstruction. The autopsy got the same results with imageological examination. The case of death was deduced to be fall leading to systemic polytrauma. CONCLUSION: Application of MSCT can be used as the complimentary for traditional autopsy in the analysis of injury manner of fall from height.

[Research Advances in Postmortem Chemistry].

Postmortem chemistry is becoming more and more essential in routine forensic pathology and has made considerable progress over the past years. Biochemical analyses of vitreous humor, blood, urine and cerebrospinal fluid may provide important information in determining the cause of death or in elucidating forensic issues. Postmortem chemistry may be essential for the determination of cause of death when morphological methods (diabetes mellitus, alcoholic ketoacidosis and electrolytic disorders) cannot detect the pathophysiological changes involved in the death process. It can also provide many information in other forensic situations, including myocardial ischemia, sepsis, inflammation, infection, anaphylaxis and hormonal disturbances. The most recent relevant research advances on glucose metabolism, liver function, cardiac function, renal function, sepsis, inflammation, infection, anaphylaxis and hormonal aspect are hereby reviewed.