[Characteristics and related factors of viral nucleic acid negative conversion in children infected with Omicron variant strain of SARS-CoV-2].

Objective: To understand the characteristics and associated factors of viral nucleic acid conversion in children infected with Omicron variant strain of SARS-CoV-2 in Shanghai. Methods: The clinical symptoms, laboratory results and other data of 177 children infected with SARS-CoV-2 who were hospitalized in Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University (designated hospital for SARS-CoV-2 infection in Shanghai) from April 25 to June 8, 2022 were retrospectively analyzed. According to the chest imaging findings, the children were divided into mild and common type groups. According to their age, the unvaccinated children were divided into<3 years old group and 3-<18 years old group. According to the vaccination status, the children aged 3-<18 year were divided into non-vaccination group, 1-dose vaccination group and 2-dose vaccination group. Comparison between groups was performed by independent sample t-test and analysis of variance, and multivariate linear regression analysis was used for multivariate analysis. Results: Among the 177 children infected with Omicron variant of SARS-CoV-2, 96 were males and 81 were females, aged 3 (1, 6) years. The time of viral nucleic acid negative conversion was (10.3±3.1) days. The 177 children were 138 cases of mild type and 39 cases of common type. Among the children aged 3-<18 years old, 55 cases were not vaccinated, 5 cases received 1-dose and 36 cases received 2-dose vaccination. Among the 36 children who received 2 doses of vaccination, the time of viral nucleic acid negative conversion was shorter in those vaccinated within 6 months than those over 6 months ((7.1±1.9) vs. (10.8±3.0) d, t=-3.23, P=0.004). Univariate analysis showed that the time of nucleic acid negative conversion of SARS-CoV-2 was associated with age, underlying diseases, gastrointestinal symptoms, white blood cell count, proportion of neutrophils, proportion of lymphocytes, and the number of doses of SARS-CoV-2 vaccine (t=3.87, 2.55, 2.04, 4.24, 3.51, 2.92, F=16.27, all P<0.05). Multiple linear regression analysis showed that older age (ß=-0.33, 95% CI -0.485--0.182, P<0.001) and more doses of vaccination (ß=-0.79, 95% CI -1.463--0.120, P=0.021) were associated with shortened nucleic acid negative conversion time in children, while lower lymphocyte proportion (ß=-0.02, 95% CI -0.044--0.002, P=0.031) and underlying diseases (ß=1.52, 95% CI 0.363-2.672, P=0.010) were associated with prolonged nucleic acid negative conversion time in children. Conclusion: The children infected with Omicron variant of SARS-CoV-2 with reduced lymphocyte proportion and underlying diseases may have longer time of viral nucleic acid negative conversion,while children with older age and more doses of vaccination may have shorter time of viral nucleic acid negative conversion.

[Risk factors of anxiety during anesthesia induction in children undergoing eye and ear-nose-throat surgery].

Objective: To explore the risk factors of anxiety during anesthesia induction in children undergoing eye and ear-nose-throat (ENT) surgeries. Methods: The clinical data of 930 children who underwent eye and ENT surgeries in the Eye & ENT Hospital of Fudan University from January to December 2019 were collected. The outcome variable was the degree of anxiety during anesthesia induction. Demographic information about the children and their family members, anxiety scores and the usage of preoperative sedative drugs were collected as the exposure factors. The risk factors of anxiety during anesthesia induction were determined by logistic regression analysis. Results: A total of 930 children were included in the study, of which 56(6.0%) cases developed anxiety during the induction period. Univariate logistic regression analysis showed that age (OR=0.72, 95%CI:0.61-0.86, P<0.001), anxiety grading of children by medical evaluation method (mild as the reference, moderate OR=5.42, 95%CI:2.92-10.07, P<0.001; severe OR=7.53, 95%CI: 2.54-22.29, P<0.001), Modified Yale Preoperative Anxiety Scale (mYPAS) score at arrival in the preoperative waiting room (OR=1.05, 95%CI:1.02-1.07, P<0.001) and sedation score (OR=0.48, 95%CI: 0.30-0.76, P<0.001) were risk factors for the development of anxiety during the induction period. Multivariate logistic regression analysis revealed that anxiety grading of children by medical evaluation method was a risk factor for affecting anxiety in the induction period (mild as the reference, moderate OR=4.08, 95%CI:1.81-9.18, P<0.01; severe OR=4.95, 95%CI:1.26-19.44, P=0.022). Conclusion: Anxiety grading of children by medical evaluation method is an essential risk factor for predicting anxiety during induction period.

Onset of inverse magnetic energy transfer in collisionless turbulent plasmas.

Inverse magnetic energy transfer from small to large scales is a key physical process for the origin of large-scale strong magnetic fields in the universe. However, so far, from the magnetohydrodynamic perspective, the onset of inverse transfer is still not fully understood, especially the underlying dynamics. Here, we use both two-dimensional and three-dimensional particle-in-cell simulations to show the self-consistent dynamics of inverse transfer in collisionless decaying turbulent plasmas. Using the space filtering technique in theory and numerical analyses, we identify magnetic reconnection as the onset and fundamental drive for inverse transfer, where, specifically, the subscale electromotive force driven by magnetic reconnection do work on the large-scale magnetic field, resulting in energy transfer from small to large scales. The mechanism is also verified by the strong correlations in locations and characteristic scales between inverse transfer and magnetic reconnection.

Orbital competition of Mn3+ and V3+ ions in Mn1+x V2-x O4.

The structural and magnetic properties of Mn1+x V2-x O4 (0 < x ⩽ 1) have been investigated by the heat capacity, magnetization, x-ray diffraction and neutron diffraction measurements, and a phase diagram of temperature versus composition was built up. For x ⩽ 0.3, a cubic-to-tetragonal (c > a) phase transition was observed. For x > 0.3, the system maintained the tetragonal lattice. Although the collinear and noncollinear magnetic transitions of V3+ ions were obtained in all compositions, the canting angles between the V3+ ions decreased with Mn3+-doping, and the ordering of the Mn3+ ions was only observed as x > 0.4. In order to study the dynamics of the ground state, the first principles simulation was applied to analyze not only the orbital effects of Mn2+, Mn3+, and V3+ ions, but also the related exchange energies.

Double-cone ignition scheme for inertial confinement fusion.

While major progress has been made in the research of inertial confinement fusion, significant challenges remain in the pursuit of ignition. To tackle the challenges, we propose a double-cone ignition (DCI) scheme, in which two head-on gold cones are used to confine deuterium-tritium (DT) shells imploded by high-power laser pulses. The scheme is composed of four progressive controllable processes: quasi-isentropic compression, acceleration, head-on collision and fast heating of the compressed fuel. The quasi-isentropic compression is performed inside two head-on cones. At the later stage of the compression, the DT shells in the cones are accelerated to forward velocities of hundreds of km s-1. The head-on collision of the compressed and accelerated fuels from the cone tips transfer the forward kinetic energy to the thermal energy of the colliding fuel with an increased density. The preheated high-density fuel can keep its status for a period of approximately 200 ps. Within this period, MeV electrons generated by ps heating laser pulses, guided by a ns laser-produced strong magnetic field further heat the fuel efficiently. Our simulations show that the implosion inside the head-on cones can greatly mitigate the energy requirement for compression; the collision can preheat the compressed fuel of approximately 300 g cm-3 to a temperature above keV. The fuel can then reach an ignition temperature of greater than 5 keV with magnetically assisted heating of MeV electrons generated by the heating laser pulses. Experimental campaigns to demonstrate the scheme have already begun. This article is part of a discussion meeting issue 'Prospects for high gain inertial fusion energy (part 1)'.

[Application effects of self-made simple vacuum sealing drainage device in postoperative treatment of sural neurocutaneous flap transplantation in the foot and ankle].

Objective: To investigate the application effects of self-made simple vacuum sealing drainage (VSD) device in the postoperative treatment of sural neurocutaneous flap transplantation in the foot and ankle. Methods: From January 2017 to January 2019, 36 patients with foot and ankle skin defects and bone exposure admitted to People's Hospital of Xinjiang Uygur Autonomous Region met the inclusion criteria, and a retrospective cohort study was conducted. According to the bandaging method of the operative area, simple negative pressure group and antibacterial dressing group were both allocated with 18 patients, with 12 males and 6 females in the former group, 14 males and 4 females in the latter group, aged (41.6±2.8) and (42.3±2.6) years, respectively. Patients in the two groups all received sural neurocutaneous flap transplantation. Patients in antibacterial dressing group received nano silver antibacterial dressing change in the operative area, and the dressing was changed once every 3 days. In simple negative pressure group, the operative area was sealed with a simple VSD device made of gauze, silicone sputum suction tube with holes cut out, and biological permeable membrane, etc., which was connected with the wall central negative pressure suction system for continuous VSD treatment of -40.0 to -16.6 kPa. The negative pressure material was changed once every 5 days. The number of dressing change, the pain score evaluated by Numeric Rating Scale during each dressing change, the cost of dressing change, and the degree of flap swelling evaluated on the 3rd and 5th day after surgery were recorded, and the flap survival was observed. Data were statistically analyzed with independent sample t test, Wilcoxon rank sum test, and chi-square test. Results: The number of dressing change of patients in simple negative pressure group was (3.4±0.5) times, which was significantly less than (7.0±0.8) times in antibacterial dressing group (t=15.338, P<0.01). The pain score during dressing change of patients in simple negative pressure group was (4.3±0.8) points, which was significantly lower than (6.8±0.7) points in antibacterial dressing group (t=10.168, P<0.01). The cost of dressing change of patients was similar between the two groups. On the 3rd and 5th day after surgery, the degrees of flap swelling of patients in simple negative pressure group were significantly superior to those in antibacterial dressing group (Z=4.448, 2.395, P<0.05 or P<0.01). The flap survival of patients in simple negative pressure group was significantly superior to that in antibacterial dressing group (χ(2)=4.500, P<0.05). Conclusions: Compared with the traditional dressing bandage, the self-made simple VSD device used after sural neurocutaneous flap transplantation can reduce the frequency of dressing change, relieve the pain of dressing change and the swelling of flap, and promote the flap survival, which is worth popularizing and applying in clinic.

Experimental Evidence of Kinetic Effects in Indirect-Drive Inertial Confinement Fusion Hohlraums.

We present the first experimental evidence supported by simulations of kinetic effects launched in the interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona plasma of the compressed pellet at the Shenguang-III prototype laser facility. Solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron yield is quenched, DD fusion yield from the corona plasma provides a direct measure of the kinetic effects inside the hohlraum. An anomalous large energy spread of the DD neutron signal (∼282 keV) and anomalous scaling of the neutron yield with the thickness of the carbon-deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these results can be attributed to kinetic shocks that arise in the hohlraum-wall-ablator interpenetration region, which result in efficient acceleration of the deuterons (∼28.8 J, 0.45% of the total input laser energy). These studies provide novel insight into the interactions and dynamics of a vacuum hohlraum and near-vacuum hohlraum.

Mutational specificities of environmental carcinogens in the lacI gene of Escherichia coli: IV. The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

We have determined the mutational specificity of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by the characterization of 58 induced Escherichia coli lacI-d mutants at the DNA sequence level. Metabolic activation of NNK was carried out using the S9 fraction from Aroclor 1254-treated rats. G:C----A:T transitions dominated the spectrum, accounting for 55% of the mutations recovered. The other base substitutions recovered include three A:T----G:C transitions as well as two A:T----T:A, three A:T----C:G, five G:C----C:G and five G:C----T:A transversions. Other classes of mutational events included two deletions, three duplications and three frame-shifts. The complexity of the NNK mutational spectrum appears consistent with a model that this compound induces mutations by both the methylation and the pyridoloxobutylation of DNA.