LED-based visible light communication for color image and audio transmission utilizing orbital angular momentum superposition modes.

Twisted light has recently gained enormous interest in communication systems ranging from fiber-optic to radio frequency regimes. Thus far, the light-emitting diode (LED) has not yet been exploited for orbital angular momentum (OAM) encoding to transmit data, which, however, could open up an opportunity towards a new model of secure indoor communication. Here, by multiplexing and demultiplexing red, green and blue (RGB) twisted beams derived from a white light emitting diode, we build a new visible light communication system with RGB colors serving as independent channels and with OAM superposition modes encoding the information. At the sender, by means of theta-modulation, we use a computer-controlled spatial light modulator to generate two-dimensional holographic gratings to encode a large alphabet with 16 different OAM superposition modes in each RGB channel. At the receiver, based on supervised machine learning, we develop a pattern recognition method to identify the characteristic mode patterns recorded by CCD cameras, and therefore, decoding the information. We succeed in demonstrating the transmission of color images and a piece of audio over a 6-meter indoor link with the fidelity over 96%.

Theta-modulated generation of chromatic orbital angular momentum beams from a white-light source.

We demonstrate a simple experiment to produce chromatic orbital angular momentum (OAM) beams from a white-light source based on theta-modulation. The array of pixels of a single spatial light modulator (SLM) is divided into four sub-domains, each of which individually displays a holographic grating both for producing the desired OAM beam and for modulating the orientation of the blazed grating. In the Fourier plane of a 4f optical system, a tailor-made spatial filter is employed for the coloration of various OAM beams with different colors. In the imaging plane, we record the generated chromatic OAM beams of different topological charges as well as their superpositions, which appear as mixtures of red, green and blue (RGB) in different proportions. Our work may find direct application in optical information processing and in free-space optical communications.

Association of tryptophan hydroxylase-2 polymorphisms with oppositional defiant disorder in a Chinese Han population.

BACKGROUND: Oppositional defiant disorder (ODD) is a behavioral disorder of school-age population. It is well known that 5-HT dysfunction is correlated with impulsivity, which is one of the common characteristics of ODD. The enzyme tryptophan hydroxylase-2 (TPH-2) synthesizes 5-HT in serotonergic neurons of the midbrain raphe. The purposes of this study were to investigate the potential association of TPH-2 polymorphisms with susceptibility to ODD in a Han Chinese school population. METHODS: Four polymorphisms (rs4570625, rs11178997, rs1386494 and rs7305115) of the TPH-2 gene were analyzed by using polymerase chain reaction and DNA microarray hybridization in a case-control study of 276 Han Chinese individuals (124 ODD and 152 controls). RESULTS: In single marker analyses,there was a significant difference in the genotype (χ 2  = 4.163, P = 0.041) and allele frequency (χ 2  = 3.930, P = 0.047) of rs1386494 between ODD and control groups. Haplotype analyses revealed higher frequencies of haplotypes TA (rs4570625-rs11178997), TAG (rs4570625-rs11178997-rs1386494), TAA (rs4570625-rs11178997-rs7305115) and TAGA (rs4570625-rs11178997-rs1386494-rs7305115), but lower frequencies of haplotypes GA (rs4570625-rs11178997) and GAG (rs4570625-rs11178997-rs1386494) in ODD compared to control groups. CONCLUSIONS: These findings suggest the role of these TPH-2 gene variants in susceptibility to ODD. Some haplotypes might be the risk factors for Chinese Han children with ODD, while others might be preventable factors.

[Transmission and Growth Characteristics of Severe PM2.5 Pollution Events from 2013 to 2021 in Xingtai, Hebei].

The correlation between the growth rate of PM2.5 with transport source, atmospheric circulation, and wind field were analyzed, focusing on the severe and above pollution process (SAAP) in Xingtai, Hebei Province from 2013 to 2021. The results showed that from 2013 to 2021, a total of 164 pollution processes and 103 SAAP occurred in Xingtai. In the ground circulation, although the probability occurrence of the inverted trough was low, the probability of pollution was the highest (61.1%), followed by the high-pressure control type (>50.0%). In the 500 hPa, the control of the straight westerly wind belt had the highest probability of severe and above pollution (20.7%), followed by the post-trough type (16.1%), with the highest occurrence frequency. In SAAP, the distribution of the PM2.5 hourly growth rate (ΔPM2.5) was mainly concentrated between ±150 µg·(m3·h)-1, and the PM2.5 hourly growth rate was positive (+ΔPM2.5), contributing 61.7%. Among them, the average proportion of explosive growth was 13.9% (from 2013 to 2021), and the overall trend was decreasing annually. In the full wind speed, in terms of occurrence frequency and pollution probability, north-east (NE) was the wind direction most closely related to air pollution, especially severe and above pollution. The mean value of ΔPM2.5 in SAAP was lower than that of quiet wind in most wind directions. However, in some of the east-north (EN) and south-west (SW) wind direction intervals, the mean ΔPM2.5 in moderate wind speed was significantly higher than that of quiet wind (related to pollution transmission). The impact of larger wind speed on ΔPM2.5 was more complicated. The backward trajectories showed that the backward trajectories of slow, rapid, and explosive growth in SAAP could be divided into three main paths:west-north, east-north, and south. With the acceleration of the growth rate, the proportion of the west-north air mass gradually increased. The humidity (RH) of the slow-growth air mass was relatively large (more than 80% RH>50%), the relative humidity of the rapidly growing air mass was relatively concentrated (mainly distributed in 35%-55%), and the proportion of low-humidity (<50%) air masses increased significantly (by approximately 63%) in the explosive growth. The simulation analysis showed that the types of SAAP pollution could be divided into five categories:local accumulation, east-northern transmission, north-west transmission, mixed transmission, and south transmission. Among them, the proportion of mixed transmission was the highest, followed by that of the north-west transmission. The high and low-altitude configurations with the highest occurrence probability among the southerly transmission, the local accumulation type, and the north-easterly transport type were all high-altitude trough rear type combined with ground equalization field type. Among the north-westerly type, the high-pressure on the ground with the behind trough on high-altitude had the highest probability of occurrence. In mixed transmission, the probabilities of various circulation ratios were relatively balanced.

Laser-Triggered High Graphitization of Mo2C@C: High Rate Performance and Excellent Cycling Stability as Anode of Lithium Ion Batteries.

Fast electron/ion transport and cycling stability of anode materials are key factors for achieving a high rate performance of battery materials. Herein, we successfully fabricated a carbon-coated Mo2C nanofiber (denoted as laser Mo2C@C) as the lithium ion battery anode material by laser carbonization of PAN-PMo12 (PAN = Polyacrylonitrile; PMo12 = H3PMo12O40). The highly graphitized carbon layer in laser Mo2C@C effectively protects Mo2C from agglomeration and flaking while facilitating electron transfer. As such, the laser Mo2C@C electrode displays an excellent electrochemical stability under 5 A g-1, with a capacity up to 300 mA h g-1 after 3000 cycles. Furthermore, the extended X-ray absorption fine structure results show the existence of some Mo vacancies in Mo2C@C. Density functional theory calculations further prove that such vacancies make the defective Mo2C@C composites energetically more favorable for lithium storage in comparison with the intact Mo2C.

Near-perfect spectrally-selective metasurface solar absorber based on tungsten octagonal prism array.

Solar selective absorbers influence the photothermal efficiency of high-temperature solar thermal applications directly and significantly. In present work, a metasurface absorber consisting of an octagonal prism array is proposed, optimized and analyzed. Firstly, the structure parameters of the absorber are optimized, finding the optimal absorber achieves near-perfect spectrally-selectivity compared with the perfect solar absorber. The high solar absorptivity of 0.9591, low emissivity of 0.1594-0.3694, and high photothermal efficiency of 94.72-83.10% are achieved at 1073-1573 K and 1000 suns. Then, the mechanisms leading to the excellent spectral selectivity are investigated, suggesting that the coupling effects of multi-plasmon resonance modes and the impedance matching lead to the high solar absorptivity. Meanwhile, the impedance mismatching is the mechanism to minimize the emissivity in the mid-IR region. Moreover, whether the spectral absorptivity can be changed by structural parameters is investigated, suggesting that the excircle diameter of the first tungsten octagonal prism and the height of SiO2 under the octagonal prism can influence the spectral absorptivity obviously. Finally, the metasurface absorber is demonstrated to be highly insensitive to both polarization and incident angles. These results suggest that the proposed metasurface absorber should be suitable for high-temperature solar thermal devices.

Insights into the Superstable Mineralization of Chromium(III) from Wastewater by CuO.

The removal of CrIII ions from contaminated wastewater is of great urgency from both environmental protection and resource utilization perspectives. Herein, we developed a superstable mineralization method to immobilize Cr3+ ions from wastewater using CuO as a stabilizer, leading to the formation of a CuCr layered double hydroxide (denoted as CuCr-LDH). CuO showed a superior Cr3+ removal performance with a removal efficiency of 97.97% and a maximum adsorption capacity of 207.6 mg/g in a 13000 mg/L Cr3+ ion solution. In situ and ex situ X-ray absorption fine structure characterizations were carried out to elucidate the superstable mineralization mechanism. Two reaction pathways were proposed including coprecipitation-dissolution and topological transformation. The mineralized product of CuCr-LDH can be reused for the efficient removal of organic dyes, and the adsorption capacities were up to 248.0 mg/g for Congo red and 240.1 mg/g for Evans blue, respectively. Moreover, CuCr-LDH exhibited a good performance for photocatalytic CO2 reduction to syngas (H2/CO = 2.66) with evolution rates of 54.03 µmol/g·h for CO and of 143.94 µmol/g·h for H2 under λ > 400 nm, respectively. More encouragingly, the actual tanning leather Cr3+ wastewater treated by CuO showed that Cr3+ can reduce from 3438 to 0.06 mg/L, which was much below discharge standards (1.5 mg/L). This work provides a new approach to the mineralization of Cr3+ ions through the "salt-oxide" route, and the findings reported herein may guide the future design of highly efficient mineralization agents for heavy metals.

[Clinical significance of 5-HT and DA levels in serum and cerebrospinal fluid of the patients with delayed encephalopathy after acute carbon monoxide poisoning].

OBJECTIVE: To explore the changes and the clinical significance of 5-hydroxytryptamine (5-HT), dopamine (DA) levels in serum and cerebrospinal fluid (CSF) of patients with delayed encephalopathy (DEACMP) after acute carbon monoxide poisoning. METHODS: The dynamic detection of 5-HT and DA levels in serum and CSF from 42 patients with DEACMP was performed with high performance liquid chromatography (HPLC). The condition changes of patients with DEACMP were analyzed with three types of scales: the activity of daily living scale (ADL), information memory concentration test (IMCT) and Hasegawa's dementia scale (HDS); these changes were compared with those from 38 other encephalopathy patients and 38 non-encephalopathy patients, respectively. RESULTS: Before treatment, the serum 5-HT and DA levels [(662.61 ± 178.50) and (155.74 ± 60.32) nmol/L, respectively] of DEACMP group were both significantly lower than those [(914.08 ± 198.04) and (225.70 ± 48.53) nmol/L] of non-encephalopathy group (P < 0.05); the serum DA level of DEACMP group was also significantly lower than that [(243.57 ± 66.94) nmol/L] of other encephalopathy group (P < 0.05); the serum 5-HT level of DEACMP group was not significantly different from that [(729.54 ± 299.87) nmol/L] of other encephalopathy group (P > 0.05). After treatment, the serum 5-HT and DA levels [(714.08 ± 170.47) and (192.18 ± 33.07 nmol/L, respectively)] of DEACMP group elevated to various extent, but only serum DA level was significantly higher than that before treatment (P < 0.05). Before treatment, the CSF 5-HT and DA levels of DEACMP group were significantly lower than those of non-encephalopathy group and those of other encephalopathy group (P < 0.05). After treatment, the CSF 5-HT level (232.44 ± 54.28 nmol/L) was similar to normal level and significantly higher than that before treatment (P < 0.05); the CSF DA level [(56.83 ± 12.85) nmol/L] of DEACMP group increased only slightly (P > 0.05). In DEACMP group, ADL score (50.64 ± 7.23), HDS score (8.55 ± 8.08) and IMCT score (4.95 ± 7.30) before treatment were significantly different from those (8.5 ± 8.08, 4.95 ± 7.30 and 15.64 ± 10.90) after treatment (P < 0.01). In DEACMP group, there wasa negative correlation between DA level changes and HDS score changes, when the DA levels and HDS scores before treatment were compared with those after treatment (P < 0.05). CONCLUSION: The dynamic changes of 5-HT and DA levels in serum and CSF of patients with DEACMP consisted basically with the patient's condition change. The dynamically detected 5-HT and DA levels can be used as the biological indicators to reflect the condition change and treatment effects of DEACMP patients.

Analysis on the impact of two winter precipitation episodes on PM2.5 in Beijing.

In this paper, the circulation background, the characteristics of meteorological elements configuration in the boundary layer and the stable meteorological conditions in two precipitation episodes (during February 19-21, 2015 and February 10-13, 2016, respectively) within the Beijing-Tianjin-Hebei region are compared and analyzed. Data from conventional meteorological observations, air quality monitoring, reanalysis and numerical models are used. The results show that before the two precipitation processes in 2015 and 2016, the circulations in the middle and high latitudes of Asia and Europe demonstrate "two troughs and one ridge". Besides, the weather is stable and the pollutant concentration is relatively high. During the precipitation, the circulation is relatively stable for the episode in 2015, and no obvious change in the synoptic system is observed. However, during the episode in 2016, the formation of blocking high and the enhancement of the average ridge in western Asia cause obvious change in the circulation. The simulation results show that significant removal can be detected in both cases, and the PM2.5 wet deposition fluxes are 647 g/ha and 486 g/ha, respectively, with the removal in 2015 slightly stronger than that in 2016. The removal and dissipation of pollutants is determined by the atmospheric diffusion conditions and the precipitation, especially in the former episode. In the case of February 2016, good diffusion conditions and the precipitation demonstrate obvious PM2.5 removal effect. In the case of February 2015, the longstanding calm wind with high humidity and the physical quantity configuration in the lower mixed layer lead to the poor pollutant removal.

Controllable Modulation of Defects for Layered Double Hydroxide Nanosheets by Altering Intercalation Anions for Efficient Electrooxidation Catalysis.

Hydrazine (N2 H4 ) is considered as one of the most potential energy storage materials in liquid fuel cells, as it contains high energy and power density, and the high-efficiency oxidation of N2 H4 in fuel cells has drawn great attention. However, the most used catalysts are expensive noble metal catalysts, thus the development of highly efficient non-noble metal catalysts is crucial to reduce the cost of hydrazine oxidation in practical industry. Herein, we synthesized a series of CoFe-layered double hydroxides (CoFe-LDHs) intercalated with different anions via a simple one-step co-precipitation method for the electrooxidation of hydrazine. Through altering the intercalated anions of CoFe-LDHs, the defects and the electronic structure can be well controlled, and the catalytic performance for the electrooxidation of hydrazine were well promoted by using NO3 - intercalated into CoFe-LDH compared with other anions (like Cl- , BO3 3- , CO3 2- ). This work developed a series of hydrazine electrooxidation catalysts and established the relationship between the intercalated anions, the fine structure of the catalyst and the electrocatalytic performance.

[Characteristics of Two Pollution Episodes Before and After City Heating in Beijing from February to March of 2019].

The characteristics of meteorological conditions and pollutant concentrations were analyzed based on two pollution episodes before and after city heating in Beijing during February to March of 2019. The backward trajectory and WRF-CAMx models were used to analyze the evolution of pollutants before and after city heating, and the influences of meteorological conditions, regional transport, and secondary transformation on the episodes were discussed. There was little difference in the average ρ(PM2.5) between February 21-24 (episode 1) and March 18-20 (episode 2), with concentrations of 100.1 µg·m-3 and 97.2 µg·m-3, respectively. However, compared with that of episode 2, in episode 1 the average peak value was higher with two peak stages, the diurnal variation was clearer, and the process developed much more rapidly. Moreover, episode 1 was regional pollution, while episode 2 was more related to local pollution in Beijing. The SO2 concentrations in both episodes were not higher than 16 µg·m-3, thereby indicating the effectiveness of coal-burning treatment and other measures. In addition, two peaks occurred in the diurnal fluctuation of SO2 in episode 1, whereas only one peak occurred for episode 2. In episode 1, the CO concentration was high and the ratio of ρ(CO)/ρ(SO2) increased around February 22-23 (phase 1); moreover, the pollutant concentrations in the central and southern areas of the Beijing-Tianjin-Hebei region and those in the background sites located in the southern part of the Beijing plain were higher than those in the urban area, thereby indicating that the diffusion conditions of episode 1 were unfavorable and the first PM2.5 peak was mainly affected by regional transport. A high ratio of ρ(PM2.5)/ρ(CO) in episode 2 suggested a slightly larger proportion of secondary generation for PM2.5, whereas higher ratios of ρ(NO2)/ρ(CO), ρ(SO2)/ρ(CO), and ρ(SO42-)/ρ(PM2.5) in episode 2 and the similar SOR value to that of episode 1 demonstrated that episode 1 was more advantageous for gas phase transformation and episode 2 was more affected by the coal industry. Phased analysis of episode 1 showed that the indicators of second generation for PM2.5 in phase 2 (around February 23-24) of episode 1 and episode 2 were similar, and both were higher than that in phase 1 of episode 1, which implied that the second PM2.5 peaks of episode 1 and episode 2 were mainly related to local emissions and chemical conversion. Both WRF-CAMx with and without assimilation experiments could better reproduce the temporal variation in pollutants, and the correlation between the simulation and observations increased but with lower values after assimilation. The model performance for the PM2.5 trend simulation significantly increased with data assimilation, and the simulated lower NO2 in February and higher NO2 in March as well as the overestimated SO2 were also improved. In addition, the pollutant concentration simulation in Beijing was more sensitive to that of Hebei in episode 1, which suggested that episode 1 was more affected by regional transport. The simulation ability for the rapid growth of pollutants needs to be promoted, and the response of pollutant types to emission reduction and the feedback related to the atmospheric oxidant and aerosol properties may be important for the simulation effect, which all require further study.

[Relationship Between Atmospheric Visibility and PM2.5 Concentrations and Distributions].

Monitoring data were used to analyze the relationships among relative humidity (RH), visibility, and PM2.5 concentrations. A strong, linear relationship expression between the extinction coefficient and PM2.5 concentrations at different relative humidities is proposed. The mean correlation coefficient at RH 40%-90% was higher than 0.75 for most of Central and Eastern China, and reached 0.9 in Beijing. Comparatively, the extinction efficiency of PM2.5 was much larger in Beijing, the Yangzi River Delta Region, and Sichuan than in other regions. However, the influence of RH on visibility varied from region to region. In Beijing, RH dominated the decrease in visibility when RH>90%, while in Guangzhou, this was the case when RH>80%. From 1980 to 1996, the annual variation in PM2.5 concentrations was not significant in Beijing and the PM2.5 concentrations were significantly higher than in the 2000s because of the dominant mode of heating. From 1997 to 2009, PM2.5 concentrations in Beijing showed a slow downward trend, and from 2010 to 2012, showed an upward trend. Since 1980, PM2.5 concentrations in the entire country have been rising. PM2.5 concentrations have always been higher in North China than in other parts of the country.

Gradual edge enhancement in spiral phase contrast imaging with fractional vortex filters.

In the spiral phase contrast imaging, the integer spiral phase plate (SPP) are generally employed to perform the radial Hilbert transform on the object. Here we introduce fractional SPP filters, instead of the integer ones, to investigate the gradual formation of edge enhancement for pure phase objects. Two spatial light modulators are used in our experimental configuration. One is addressed to display the pure phase object of a five-pointed star, while the other serves as a dynamic filter of fractional topological charge Q. Of interest is the observation of the complete reversal of the edge and background brightness by gradually changing the fractional vortices from Q = 0 to 1. The experimental results were well interpreted based on the OAM spectra of fractional SPP, which indicates that the filtered output image can be considered as a coherent superposition of all possible images that are individually resulted from the integer OAM filtering. Besides, we show that the spiral phase contrast effect can still be observed in real time for a rotating three-leaf clover. Our results may find potential applications in the optical microscopic imaging.

A randomized controlled trial of olanzapine improving memory deficits in Han Chinese patients with first-episode schizophrenia.

Olanzapine is an atypical antipsychotic for the treatment of schizophrenia, in which memory impairment is a core deficit. The methods of positive and negative syndrome scale (PANSS), Wechsler memory scale-4th edition (WMS-IV) and event-related potential (ERP) were used to study the effects of olanzapine on the cognitive function in the first-episode schizophrenic patients. We performed multicentre, randomized, double-blind, placebo-controlled, parallel-group clinical trial to study the cognitive functioning in Han Chinese first-episode schizophrenic patients in a 12-week treatment regime with olanzapine (129 cases) or placebo (132 cases). The results showed that (1) the patients with first-episode schizophrenia showed significant deficits in the long-term memory, short-term memory, immediate memory and memory quotient by WMS-IV assessment, and decreases the total scores, positive symptoms, negative symptoms and general psychopathology by PANSS assessment; (2) olanzapine could significantly improve the PANSS scores including total scores, positive symptoms, negative symptoms and general psychopathology in the first-episode schizophrenic patients; (3) olanzapine could significantly improve the short-term memory, immediate memory and memory quotient in the first-episode schizophrenic patients; and (3) although the latencies of P(2), N(2) and P(3) were significantly prolonged, P(2) and P(3) amplitudes were decreased and the latencies of N(1) did not change, olanzapine did not influence any P(300) items in the first-episode schizophrenic patients. The data suggested that that olanzapine could improve cognitive process, such as memorizing and extraction of the information although there were many changes of cognitive functions in Han Chinese first-episode schizophrenic patients.