statement: In patients suspected of having COVID-19, the initial chest CT showed high sensitivity, but low specificity. Key Results:(1) The sensitivity, specificity, positive predictive value, and negative predictive value (with 95% confidence intervals) were 93% (85-97%), 53% (27-77%), 92% (83-96%), 42% (18-70%), respectively. Similar results were shown in both geographic regions studied.(2) There were no significant differences in the distribution of positive rates of tests in the two geographic regions between CT (P=0.423) and reverse transcription polymerase chain reaction testing (P=0.931). AbbreviationsPPV= positive predictive value (PPV) NPV= negative predictive value (NPV) 95% CI=95% confidence interval RT-PCR = reverse transcription polymerase chain reaction CT=computed tomography (CT) Abstract Background: Coronavirus disease 2019 (COVID-19) is a new viral respiratory disease that has recently emerged from China, becoming a pandemic. However, few studies have analyzed 3data regarding the clinical performance of chest computed tomography (CT) obtained in subjects with suspected COVID-19 at the initial presentation to medical facilities. Objective:The purpose of the present study was to evaluate the performance of chest CT the initial presentation of patients with suspected COVID-19.Methods: Data from 103 patients who were under investigation for COVID-19 based on inclusion criteria according to WHO Interim Guidance were retrospectively collected from January 21, 2020 to February 14, 2020. All patients underwent chest CT scanning and reverse transcription polymerase chain reaction testing (RT-PCR) for COVID-19 at hospital presentation. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) (with 95% confidence intervals) were calculated to evaluate the performance of CT. Subgroup analyses were also performed based on the geographical distribution of these cases in the province of Henan, China.Results: There were 88 /103 (85%) patients with COVID-19 confirmed by RT-PCR. The overall sensitivity, specificity, PPV, and NPV were 93% (85-97%), 53% (27-77%), 92% (83-96%), and 42% (18-70%), respectively. Similar results were shown in both geographic regions. The respective sensitivity, specificity, PPV, and NPV for chest CT in the districts of Xinyang and Zhumadian (n = 56) were 92% (80-97%), 63% (26-90%), 93% (81-98%), and 56% (23-85%), while these indicators in the district of Anyang (n = 47) were 95% (81-99%), 43% (12-80%), 90% (76-97%), and 60% (17-93%). There were no significant differences in the prevalence of positive exams in the two geographic subgroups for CT (P=0.423) or RT-PCR (P=0.931). 4Conclusion: Although initial chest CT obtained at hospital presentation showed high sensitivity in patients under investigation for COVID-19 in the two geographic regions in Henan province, the NPV was only modest, suggesting low value of CT as a screening tool.

Efficient water electrolyzers are constrained by the lack of low-cost and earth-abundant hydrogen evolution reaction (HER) catalysts that can operate at industry-level conditions and be prepared with a facile process. Here we report a self-standing MoC–Mo2C catalytic electrode prepared via a one-step electro-carbiding approach using CO2 as the feedstock. The outstanding HER performances of the MoC–Mo2C electrode with low overpotentials at 500 mA cm−2 in both acidic (256 mV) and alkaline electrolytes (292 mV), long-lasting lifetime of over 2400 h (100 d), and high-temperature performance (70 oC) are due to the self-standing hydrophilic porous surface, intrinsic mechanical strength and self-grown MoC (001)–Mo2C (101) heterojunctions that have a ΔGH* value of −0.13 eV in acidic condition, and the energy barrier of 1.15 eV for water dissociation in alkaline solution. The preparation of a large electrode (3 cm × 11.5 cm) demonstrates the possibility of scaling up this process to prepare various carbide electrodes with rationally designed structures, tunable compositions, and favorable properties.

An overview is given of the applications of short and ultrashort lasers in material processing. Shorter pulses reduce heat-affected damage of the material and opens new ways for nanometer accuracy. Even forty years after the development of the laser there is a lot of effort in developing new and better performing lasers. The driving force is higher accuracy at reasonable cost, which is realised by compact systems delivering short laser pulses of high beam quality. Another trend is the shift towards shorter wavelengths, which are better absorbed by the material and which allows smaller feature sizes to be produced. Examples of new products, which became possible by this technique, are given. The trends in miniaturization as predicted by Moore and Taniguchi are expected to continue over the next decade too thanks to short and ultrashort laser machining techniques. After the age of steam and the age of electricity we have entered the age of photons now Keywords: Micro-machining, Laser, Ablation 101, (Figure 2.3) has simulated the interaction and ablation behaviour of aluminium, copper and silicon at 266 nm wavelength. The optical penetration depth was 7, 12 and 5 nm respectively. The applied power density was in the range of 5 to 50.109 W/cm2. It was found that the material evaporates as small particles (0.3-10 nm), most of them smaller than 1 nm. The average velocity of

Reconnection of the self-generated magnetic fields in laser-plasma interaction was first investigated experimentally by Nilson et al. [Phys. Rev. Lett. 97, 255001 (2006)] by shining two laser pulses a distance apart on a solid target layer. An elongated current sheet (CS) was observed in the plasma between the two laser spots. In order to more closely model magnetotail reconnection, here two side-by-side thin target layers, instead of a single one, are used. It is found that at one end of the elongated CS a fanlike electron outflow region including three well-collimated electron jets appears. The (>1 MeV) tail of the jet energy distribution exhibits a power-law scaling. The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region, as well as additional acceleration as they are trapped inside the rapidly moving plasmoid formed in and ejected from the CS. The ejection also induces a secondary CS.

Polypyrrole/Graphene/Polyaniline (PPy/GNs/PANi) ternary nanocomposite with high thermoelectric power factor has been successfully prepared through the combination of in situ polymerization and solution process. FTIR, Raman spectra, XRD, and SEM analyses show the strong π-π interactions existed among PPy, GNs, and PANi, leading to the formation of more ordered regions in the composite. Both the in situ polymerization and solution process can enhance the dispersion homogeneity of graphene in the polymer matrix, bringing about increased nanointerfaces in the PPy/GNs/PANi composite. The thermoelectric properties of Polypyrrole/Graphene (PPy/GNs), Polyaniline/Graphene (PANi/GNs), and PPy/GNs/PANi composites are measured at different temperatures after being cold pressed. Consequently, the PPy/GNs/PANi composite with 32 wt % graphene demonstrates optimal electrical conductivity, Seebeck coefficient and extremely high power factor of up to 52.5 μ W m K, which is almost 1.6 × 10 times, 1.4 × 10 times, 2.7 times, and 3.6 times higher than those of the pure PANi, pure PPy, PPy/GNs composite, and PANi/GNs composite, respectively.