Search

An unknown proportion of out-of-hospital cardiac arrest (OHCA) is caused by intracranial hemorrhage (ICH). There is uncertainty over the role of early head computed tomography (CT) in non-traumatic OHCA due to uncertain diagnostic yield and ways to identify high-risk patients. This study aimed to identify the prevalence of ICH in non-traumatic OHCA and possible predictors.PubMed, EMBASE, and the Cochrane library were searched from inception to January 2022. Data extraction and quality assessment were independently reviewed by two authors. Meta-analyses estimated the prevalence of ICH amongst OHCA patients and pre-specified subgroups and geographical settings. Subgroup analysis were used to explore potential clinical predictors.23 studies involving 54,349 patients were included. The pooled ICH prevalence was 4.28% (95%CI: 3.31-5.24). Asia had a significantly larger risk ratio (RR = 3.93, P value 0.0001) than Europe. The ICH subgroup was significantly more likely to be female (OR: 2.16; 95%CI: 1.10-4.26), and less likely to experience shockable rhythms compared with non-shockable rhythms (OR: 0.22; 95% CI: 0.04-1.22), achieve ROSC prior to arrival (OR: 0.27; 95%CI: 0.10-0.77), and survive to discharge compared to those without ICH (OR: 0.26; 95%CI: 0.11-0.59).One in twenty OHCA have ICH at the time of presentation. An early head CT scan should be strongly considered after return of spontaneous circulation (ROSC), especially in patients who are female, with non-shockable rhythm and did not attain ROSC prior to arrival. These finding should influence clinical protocols to favor routine scans especially in Asia where prevalence is higher.

In order to improve the red luminescent properties, Sr2MgSi2O7:Eu2+,Dy3+ was selected as a blue persistent luminescent donor phosphor, while light conversion agent was utilized to tune the persistent luminescent spectra from blue to red. Composite red luminescent material Sr2MgSi2O7:Eu2+,Dy3+/light conversion agent (SMED/LCA) was fabricated with light conversion agent and Sr2MgSi2O7:Eu2+,Dy3+ at a certain mass ratio. SiO2 (Al2O3 or MgF2) were coated on the surface of SMED/LCA through heterogeneous deposition method. The structural and optical characteristics of the resulting samples were launched in terms of X-ray diffraction and emission spectrum as well as afterglow brightness. The results demonstrate that the emission spectrum exhibits two emission bands, and the peaks are located at around 470 and 615 nm. SiO2, Al2O3 and MgF2 are coated on the surface of SMED/LCA like a protective shell to maintain its stability and luminescent properties, the afterglow initial brightness is still up to 0.37 cd/m2 and the afterglow color purity calculated from CIE color coordinates is basically unchanged.

Purpose The purpose of this study was to compare the perioperative parameters of quadrant, sextant, and grid lens fragmentation patterns in femtosecond laser-assisted cataract surgery (FLACS). Design Prospective randomized clinical trial. Methods S etting : Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. S tudy population : A total of 894 eyes in 661 patients with cataracts were enrolled. I ntervention or observation procedures : the nuclear density was graded according to the Emery-Little classification. Patients received lens fragmentation using a quadrant, sextant, or grid pattern after random allocation. Evaluations included intraoperative parameters, complications, and postoperative outcomes. M ain outcome measurements : effective phacoemulsification time (EPT), intraoperative complications, visual acuity and intraocular pressure at one day postoperatively, as well as endothelial cell density, endothelial cell loss, and central corneal thickness at 1 week postoperatively. Results In grade 1 nuclei, the mean EPT in the grid group was the shortest compared to those in the quadrant (P = 0.011) and sextant (P = 0.001) groups. In grade 2 nuclei, all 3 patterns showed no significant differences in the mean EPT (P > 0.05). In grade 3 nuclei, the sextant group revealed shorter mean EPT than the grid (P = 0.017) and quadrant (P > 0.05) groups. In grades 4 and 5 nuclei, the quadrant pattern had the shortest mean EPT among all 3 patterns (P Conclusions The grid and quadrant patterns allow for shorter EPT in soft (grade 1) and hard (grades 4 and 5) nuclei, respectively. All 3 patterns can be selected for treating grade 2 nuclei. The sextant pattern may be the best option when treating grade 3 nuclei. The grid pattern should be avoided in hard nuclei combined with glaucoma or glaucoma suspect.

The pyrolysis behaviors of Huainan coal (HN coal) with three particle sizes, i.e.

Prenatal ethanol exposure (PEE) causes intrauterine growth retardation (IUGR), and the occurrence of glomerulosclerosis is closely related to IUGR. This study aimed to confirm the kidney toxic effect of PEE and explore its intrauterine programming mechanism in female offspring. The Wistar female fetuses on gestational day (GD) 20 and the adult offspring at postnatal week 24 were anesthetized and decapitated. The adult offspring kidneys in the PEE group displayed glomerular hyperplasia and glomerulosclerosis. Blood urea nitrogen (BUN) and the BUN / Serum creatinine (Scr) concentration ratio in the PEE group was increased significantly compared to the control group (P

The in-depth study of the cleavage behaviors of linkages in biomass is important for the better understanding of biomass pyrolysis mechanism. This study aimed to clarify the pyrolysis mechanism of the typical ether linkages in biomass including β-1,4-glycosidic bond, α-O-4 bond and methoxyl using cellobiose, benzylphenyl ether and guaiacol as the model compounds. Combining the detection of the key intermediates, especially radicals by SVUV-PIMS and the evaluation of the reaction pathways by density functional theory (DFT) quantum chemical calculations, it was found that the concerted cleavage of β-1,4-glycosidic bond was more kinetically favorable than homolytic cleavage and heterolytic cleavage, and the ring opening of cellobiose via the breakage of C1′-O was likely to occur before the cleavage of glycosidic bond. The α-O-4 bond in benzylphenyl ether was mainly cleaved by Cα-O homolysis, and it was easy for the formed radicals to recombine with each other to yield phenolic dimers. In the initial evolution process of methoxyl in guaiacol, homolytic demethylation was the most important unimolecular reaction, while demethoxylation and radical-induced rearrangement reactions were difficult to occur due to their high energy barriers. In the presence of the formed methyl radicals from homolytic demethylation reaction, these two reactions would occur since their energy barriers were significantly reduced at this condition.

Simultaneously measured luminosity and magnetic field induced by the return strokes in typical upward and downward flashes occurring on the 600 m-tall Canton Tower were presented. The correlation between peak relative luminosity and peak relative magnetic field induced by return strokes were examined for 4 upward and 4 downward flashes. All the flashes contained 3 or more return strokes and all the return strokes in a same flash followed the same path. Luminosity of the lightning channel close to the top of the Canton Tower exhibited characteristics of pronounced initial peak with 20–90% rise time of about 5.2 μs (arithmetic mean value, based on 43 samples) for subsequent strokes, which was inferred to be related to the secondary (typically largest) peak current at the top of the Canton Tower. The magnetic field induced by subsequent strokes exhibited characteristics of pronounced initial peak with 20–90% rise time of about 1.2 μs (arithmetic mean value, based on 47 samples). The initial peak magnetic field was modified to proportionally represent the largest peak current at the top of the Canton Tower. Roughly linear and quadratic relation between the initial peak luminosity and modified peak magnetic field were found for subsequent strokes in both upward and downward flashes. The quadratic relation fit the data slightly better than the linear relation. The ratio of peaks of luminosity to magnetic field of the downward first stroke were considerably larger than those of the subsequent strokes, the possible reasons were also discussed.

Fungal peritonitis is an inflammatory condition of the peritoneum which occurs secondary to peritoneal dialysis. Most cases of peritonitis are caused by microbial invasion into the peritoneal cavity, resulting in high morbidity and mortality. Unlike bacterial peritonitis, little is known on fungal peritonitis. Card9, an adapter protein, plays a critical role in anti-fungal immunity. In this study, by using zymosan-induced peritonitis and C. albicans-induced peritonitis mouse model, we demonstrated that fungal peritonitis was exacerbated in Card9

BackgroundOsteosarcoma is an aggressive primary malignant cancer of bone mainly occurring in adolescence with a characteristic of high metastasis and relapse rate. In our previous study, we first identified that NPR3 was significantly decreased in OS samples. Here, we purposed to investigate the effect and the possible mechanisms of NPR3 on the progression of human OS. MethodsThe expression of NPR3 in OS patients and cells was detected by qRT-PCR, and IHC analysis. The effect of the expression of NPR3 on tumour metastasis was examined in vitro and in vivo. The molecular mechanisms of the regulation of NPR3 were evaluated in vitro and in vivo. The clinical relevance of 5-year overall survival with the expression of NPR3 was evaluated in 294 patients with OS. ResultsFirstly, we indicated that NPR3 was substantially downregulated expression in OS tissues and cells by qRT-PCR and IHC assay. And the patients with lower expression of NPR3 have a poor prognosis. Functional studies revealed that over-expression of NPR3 inhibited the proliferation and invasion of cells. Meanwhile, over-expression of NPR3 markedly inhibited tumorigenesis and weakened tumour metastasis in vivo. Interestingly, we found that over-expression of NPR3 could induce autophagy, promote apoptosis and inhibit EMT. Additionally, overexpression of NPR3 decreased the phosphorylation levels of AKT and mTOR. Loss-of-function experiments displayed that effects of NPR3 were weakened by treatment with the specific autophagy inhibitor Baf-A1 and CQ. ConclusionsTaken together, these results demonstrated that down-regulation of NPR3 promote lung metastasis of human OS by promoting EMT in part through the AKT/mTOR mediated autophagy, suggesting that NPR3 has therapeutic potential for OS patients with metastasis.

Bombesin Receptor Subtype-3 (BRS-3, Bombesin-like receptor, BBIn this study, we aim to discover new agonists of BRS-3 from our natural compound libraries, providing a new probe to study the function of BRS-3.Multiple cell-based assays and in vivo experiments were performed to identify the new ligand.BRS-3 overexpression cells were coupled with FLIPR assay, homogeneous time-resolved fluorescence (HTRF) IP-ONE assay, dynamic mass redistribution (DMR) assay, β-arrestin2 recruitment assay, and western blot to determine receptor activation and downstream signaling events. To further validate the target of BRS-3, a series of in vitro and in vivo experiences were conducted, including glucose uptake, glucose transporter type 4 (GLUT4) transportation in C2C12, and oral glucose tolerance test (OGTT) in mice.We discovered and identified oridonin as a novel small molecule agonist of BRS-3, with a moderate affinity (ECOridonin, as the discovered new ligand of BRS-3, provides a valuable tool compound to investigate BRS-3's function, especially for target validation in type 2 diabetes and obesity. Oridonin is promising as a lead compound in the treatment of metabolic disorders. Compared to the known agonists of BRS-3, we can take advantage of the multiple reported pharmacological activities of ODN as a natural product and assess whether these pharmacological activities are regulated by BRS-3. This may facilitate the discovery of novel functions of BRS-3.

Background: This study purposed to construct a widely accepted prognostic nomogram in Chinese high-grade osteosarcoma (HOS) patients aged ≤ 30 years to provide insight into predicting 5-year overall survival (OS). Methods: Data of 503 consecutive HOS patients at our centre between 12/2012 and 05/2019 were retrospectively collected. The 84 clinical features, routine laboratory haematological and biochemical testing indicators of each patient at the time of diagnosis were collected. A prognostic nomogram model for predicting OS was constructed based on Cox proportional hazards model. The performance was assessed by concordance index (C-index), receiver operating characteristic curve and calibration curve. The utility was evaluated by decision curve analysis. Findings: The 5-year OS was 52.1% and 2.6% for the nonmetastatic and metastatic patients, respectively. The nomogram included nine important variables based on a multivariate analysis: tumour stage, surgical type, metastasis, preoperative neoadjuvant chemotherapy cycle, postoperative metastasis time, mean corpuscular volume, tumour-specific growth factor, gamma-glutamyl transferase and creatinine. The calibration curve showed that the nomogram was able to predict 5-year OS accurately. The C-index of the nomogram for OS prediction was 0.795 (range, 0.703-0.887). Moreover, the decision curve analysis curve also demonstrated the clinical benefit of this model. Interpretation: The nomogram provides an individualized risk estimate of the 5-year OS in patients with HOS aged ≤ 30 years in a Chinese population-based cohort. Funding Statement: This work was financially funded by the National Science Foundation of China (No. U1702283, 81972764, 81960488, 81760520, 81560471), the Joint Special Funds for the Department of Science and Technology of Yunnan Province-Kunming Medical University (No. 2017FE467-073, 2018FE001-060, 2019FE001-152, 2019FE001-078), the Scientific Research Projects of Internal Research Institutions of Medicine (Nos. 2017NS196, 2017NS197, 2018NS069, 2018NS070), the Medical Leaders of Yunnan Province (No. D-201603), the Foundation of the Young and Middle-aged Academic and Technical Leaders of Yunnan Province (No. 2017HB051), China Postdoctoral Science Foundation (No. 2018M643798XB), Training program for 100 Young and middle-aged Academic and technical backbones of Kunming Medical University and the Major Scientific and Technological Achievement Cultivation Project of Kunming Medical University (No. CGPY201703). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: All human tissue experiments were approved by the Institutional Ethics Committee of the Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital). Written informed consent forms for the experimental studies were obtained from the patients or their guardians.

The outbreak of SARS-CoV-2 in December 2019, led to the ongoing global pandemic of coronavirus disease 2019 (COVID‑19), which has claimed more than a half million lives in a few months. Enormous efforts are being made in developing vaccines and therapeutic treatment to fight against COVID-19. Inactivated SARS-CoV-2 viruses are currently used as vaccine candidates; therefore, it is important to understand the architecture of SARS-CoV-2. We have propagated and purified a clinical strain of SARS-CoV-2 and genetically and structurally characterized β-propiolactone inactivated viruses. We observed that the virus particles are roughly spherical or moderately pleiomorphic. Although a small fraction of prefusion spikes are observed, the majority of viral spikes appear nail-shaped resembling a postfusion state, where S1 protein of the spike has disassociated. Cryo-electron tomography and subtomogram averaging of these spikes yielded a density map which closely matches the overall structure of SARS-CoV S2 spike and their corresponding glycosylation sites. Our findings have major implications in SARS-CoV-2 vaccine design owing to the critical importance of prefusion immunogens. Funding: This work was supported by the Science and Technology Innovation Committee of Shenzhen Municipality(202002073000002), the National Institutes of Health grant P50AI150481 (P.Z.), the UK Wellcome Trust Investigator Award 206422/Z/17/Z(P.Z.), and the UK Biotechnology and Biological Sciences Research Council grant BB/S003339/1 (P.Z.). Conflict of Interest: The authors declare no competing financial or non-financial interests. Ethical Approval: The research received approval from the Research Ethics Committee of Shenzhen Third People's Hospital, China (approval number: 2020-038). The Research Ethics Committee waived the requirement informed consent before the study started because of the urgent need to collect epidemiological and clinical data. We analyzed the data anonymously.

This work shows a facile way of fabrication of high-performance anode material for lithium-ion batteries (LIBs). Electro-spun PAN nanofibers were firstly wrapped with mesoporous SiO2 via templating method to form a PAN@SiO2 composite nanofiber film. After magnesiothermic reduction and removal of unreacted SiO2 and byproduct, a free-standing N-doping Si/SiC/C composite nanofiber film was achieved. It can be directly applied as electrode material in LIBs without conductive additives, binders, and current collectors, and it exhibited high specific discharge capacity and good cycling stability, which was ascribed to its special composite composition and porous structure.

Anthracene derivatives constitute the active elements in high performance organic semiconductors and in order to find ubiquitous electronics applications, the investigation of new materials with high stability and mobilities is critical. Despite the versatility of substituent groups in anthracene and the extensive research works on anthracene derivatives, the exploration and discovery of high-performance anthracene derivatives can be impeded by the difficulty in molecular designing and synthesis techniques. Theoretical modeling is a powerful instrument and a variety of modeling methods with different accuracy levels have been reported. However, there is no systematic research work on theoretical prediction of the fundamental properties of anthracene derivatives so far. Here, density functional theory calculations are performed on anthracene derivatives to systematically address the prediction accuracy in energy levels as compared to our experimental data and it is shown that the PBE0/6-311G(d,p) is a more cost-effective method. Based on the influence of diverse substituent groups on energy levels, we present a strategy to design high-performance anthracene derivatives with specific energy levels, which are predicted to be excellent candidates for charge transfer materials. Therefore, the strategy may offer a guide for tailoring materials' functional properties via modifications of the molecular units before materials synthesis and open up new possibilities for the discovery of rising organic semiconductors.

Enterotoxigenic Escherichia coli (ETEC) K88 (F4) is a worldwide cause of severe diarrhoea in the offspring of some animal species such as weaned pigs. Preventing ETEC K88 (F4) attaching to the small intestine by natural feed ingredients interfering with its fimbria-receptor recognition could be an alternative method to reduce diarrhoea occurrence. The purpose of this study is to evaluate the ability of different common ingredients in the formulation of pig diets, and particularly different kinds of cereal brans, to attach ETEC K88 (F4) (adhesion test, AT) and to block its attaching to intestinal epithelial cells (IPEC-J2) (blocking test, BT) in vitro. For the feed ingredients, wheat, corn, oats, barley, rye, extruded full-fat soybean meal, soybean meal, as well as sweet whey powder, all demonstrated a clear affinity to attach ETEC K88 (F4) (P

Two kinds of warm-toned (yellow/orange-emitting) long-lasting phosphorescent composites, namely, SiO2/red-emitting color converter@SrAl2O4:Eu2+, Dy3+ (SiO2/RECC@SAOED) and PMMA/red-emitting color converter@SrAl2O4:Eu2+, Dy3+ (PMMA/RECC@SAOED), were prepared in this study. Their morphological and luminescent properties were compared with those of the uncoated SAOED phosphor and analyzed in detail. SiO2/RECC@SAOED and PMMA/RECC@SAOED particles presented a coarse surface with an increased diameter of 12 µm. In addition to the first emission peak at 525 nm similar to that of the uncoated SAOED, an emission peak occurred in the emission spectra of SiO2/RECC@SAOED and PMMA/RECC@SAOED at 610 and 612 nm, respectively. The chromaticity coordinates of SiO2/RECC@SAOED and PMMA/RECC@SAOED moved to the yellow (x = 0.3769, y = 0.5006) and orange (x = 0.4647, y = 0.4671) areas compared with those of the uncoated SAOED in the green area (x = 0.2781, y = 0.5777). The afterglow decay curve revealed that the afterglow property of SiO2/RECC@SAOED was better than that of PMMA/RECC@SAOED.

2-(4-(octyloxy)phenyl)[1]benzothieno[3,2-b][1]benzothiophene (C8-OPh-BTBT), a liquid crystal material, is designed and successfully synthesized by introducing an alkoxy side chain of BTBT core. The organic thin-film transistors (OTFTs) based on C8-OPh-BTBT are fabricated to investigate the charge transport properties and compare with that of the alkyl side chain substituted semiconductor such as C12-Ph-BTBT. The highest mobility of 8.25 cm2 V−1 s−1 in C8-OPh-BTBT-based OTFTs is obtained when fabricated at a highly ordered Smectic X (X = K or H, SmX) liquid crystal phase, which is attributed to the formation of a bilayer structure of the organic semiconductor. Notably, the mobility of alkyoxy-substituted C8-OPh-BTBT-based OTFTs is much higher than that of alkyl-substituted C12-Ph-BTBT based OTFTs, while decreasing the operating threshold voltage. This study reveals that the introduction of alkoxy side chain of BTBT core is an effective way to alleviate the high threshold voltage and improve the charge mobility, which indicates that C8-OPh-BTBT-based OTFTs have the potential in practical applications.

This study investigates the gate stress-induced mobility discrepancy in p-type single-crystal organic field-effect transistors (OFETs) on an octyltrichlorosilane (OTS)-modified SiO2/Si substrate. During measurements in atmosphere, anti-clockwise hysteresis was observed in the transfer curve, and the mobility calculated from the forward sweep was smaller than that calculated from the reverse sweep. Hysteresis has often been observed for OFETs but the mobility discrepancy has not been clearly understood. We formulated a “fast trapping vs. slow detrapping” model and suggested that the mobility values calculated from the reverse sweep represent the intrinsic property of the material. To verify the validity of this model, we investigated mobility anisotropy of an air-stable organic semiconductor, 2,7-bis(4-methoxyphenyl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (DBOP-BTBT). By measuring the single-crystal OFET characteristics of many crystals with different orientations, we observed anisotropic hole mobility calculated from the reverse sweep. The mobility along the b-axis, which corresponds to the π-π stacking direction, was 13.9 cm2 V−1 s−1, and that along the a-axis was 6.2 cm2 V−1 s−1. However, we did not see clear anisotropy when mobility was calculated from the forward sweep due to a variation in the data. The threshold voltage from the reverse and the forward sweeps showed isotropic characteristics within the range from −60 to −70 V and from −50 to −60 V, respectively. These results indicate that the numbers of filled traps were different between the reverse and the forward sweeps at the interface, and confirm the validity of our model.

In this paper, a class of optimization problems is investigated, where the objective function is the sum of N convex functions viewed as local functions and the constraints are N nonidentical closed convex sets . Additionally, it is aimed to solve the considered optimization problem in a distributed manner and thus a sequence of time-varying unbalanced directed graphs is introduced first to depict the information connection topologies. Then, the novel push-sum based constrained optimization algorithm (PSCOA) is developed, where the new gradient descent-like method is applied to settle the involved closed convex set constraints. Furthermore, the rigorous convergence analysis is shown under some standard and common assumptions and it is proved that the developed distributed discrete-time algorithm owns a convergence rate of O ( ln t t ) in general case. Specially, the convergence rate of O ( 1 t ) can be further obtained under the assumption that at least one objective function is strongly convex. Finally, simulation results are given to demonstrate the validity of the theoretical results.

Introduction With the accumulating evidence of ocular manifestations of the 2019 novel coronavirus disease (COVID-19), the study aimed to systematically summarize the ocular manifestations in COVID-19 patients. Methods The PubMed, EMBASE, Web of Science databases were searched through June 2021. Studies that provided clinical characteristics and outcomes and reported on the ocular manifestations or conjunctival swab RT-PCR tests among COVID-19 patients were included. Results A total of 30 studies involving 5,717 patients were identified. Ocular manifestations including conjunctival hyperemia (7.6%, 95% confidence interval [CI] 1.8–8.9%), conjunctival discharge (4.8%, 95% CI 1.8–8.9%), epiphora (6.9%, 95% CI 2.8–12.8%), and foreign body sensation (6.9%, 95% CI 2.4–13.0%) were observed. The positive rate of conjunctival swab tests was 3.9% (95% CI 0.2–6.4%). Severe cases of COVID-19 were associated with an increased risk of developing ocular complications (odds ratio [OR] = 2.77, 95% CI 1.75–4.40). Conclusions Despite their relatively low incidence rate in COVID-19 patients, ocular manifestations may be non-specific and present as the initial symptoms of infection. The presence of SARS-CoV-2 in the conjunctival swabs implicates the eye as a potential source of infection. Early diagnosis and proper eye protection would help prevent viral transmission.

With the development of nanoscale transducers, surface acoustic wave (SAW) with frequencies above 10 GHz can now be excited on the optical waveguides. However, the fundamental mode is very difficult to be excited for SAW at ultrahigh frequencies. Moreover, as the wavelength of SAW is reduced to below the optical wavelength, the acoustic field across the optical waveguide can no longer be approximated as uniform but is spatially periodic. Here, we develop a discussion about integrated acousto-optic (AO) interaction at ultrahigh frequencies. The electromechanical coupling coefficients of different modes are evaluated for SAW at ultrahigh frequencies. The acousto-optic overlap is analyzed to evaluate integrated AO interaction for each given acoustic wavelength and optical waveguide size. An analytic model is presented for integrated AO interaction at ultrahigh frequencies. The research shows that it would be a trade-off for the design of an integrated AO device with ultrahigh frequencies.

Small molecular organic electrochromic materials have gradually attracted the attention from academia. Although ester organic electrochromic materials show unique advantages such as significant color change, wide color adjustment range and low cost, their electrochromic mechanisms are still unclear, keeping their driving voltage and stability issues unsolved. In this article, the absorption spectra of phthalate derivatives under different conditions are calculated with time-dependent density functional theory to understand the influences on the electrochromic properties by the electronic and steric effects. By the increased conjugation and reduced steric hindrance, carbonyl linking group is found capable to enhance the absorption in the visible region and exhibit low driving voltages. Further, a new electrochromic compound is designed to improve the luminous effect and lower the driving voltage.

We examined in detail the morphology and evolution of an upward negative flash initiated from a 257-m tower in Florida. High-speed video camera images and wideband electric field records, as well as ENTLN data, were used. The upward negative flash was induced (triggered) by a single-stroke 50-kA +CG that occurred about 45 km from the tower. The 257-m tower flash contained 6 leader/return stroke sequences and 1 attempted leader that almost terminated on the tower. All the leaders exhibited bidirectional extension. Electric field waveforms produced by the return strokes (measured at a distance of 8.8 km) were bipolar and abnormally narrow (exhibited earlier zero crossings). In order to examine the origin of the observed earlier zero crossings, we used two return-stroke models of transmission line type (MTLL and MTLE) to see what model input parameters are responsible for this feature. Within the limits of those models, the observed earlier zero crossings could be explained only by a narrow input current waveform or/and its fast amplitude decay with height.

In order to obtain a red fluorescent fiber with long persistent performance, Sr2MgSi2O7:Eu2+, Dy3+ and Y2O2S:Eu3+, Mg2+, Ti4+ phosphors were prepared by high-temperature solid-phase method, then the phosphors and Rhodamine B were spun into the Polyacrylonitrile (PAN) through coaxial wet-spinning. The structure and morphology of samples were characterized by the X-ray diffraction, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and particle size analyzer. Fluorescent properties were studied based on photoluminescence spectroscopy and afterglow decay curve. The data show that Sr2MgSi2O7 has blue broadband emission due to the electronic transition of Eu2+, and the Y2O2S has red linear emission spectrum because of the electronic transition of Eu3+.The analysis results reveal that the excellent afterglow performance of Sr2MgSi2O7 plays a significant role in the secondary excitation. Rhodamine B was added in the coaxial fiber as a red light compensator through transferring the blue light to red fluorescence.

Hollow carbon nanospheres have received much interest by virtue of the special shape, low density and large interior void space, allowing their many potential applications. Here we report a template-free route to produce nitrogen-doped hollow porous carbon spheres (denoted as N-HPCSs) through amination reaction of C 60 with alkyl diamines and subsequent carbonization. The size of wall thickness and cavity of hollow carbon spheres could be easily regulated by the chain length of alkyl diamines. After carbonization in Ar atmosphere, the obtained N-HPCSs exhibited excellent activity and recyclability for hydrogenation of aromatic nitro compounds with hydrazine hydrate. The facile approach presented in this work provides a new way for preparation of doped hollow porous carbon spheres.