The Prevalence of Childhood Dysphonia: A Cross-Sectional Study

There is only very limited information on the prevalence of voice disorders, particularly for the pediatric population. This study examined the prevalence of dysphonia in a large cohort of children (n = 7389) at 8 years of age. Data were collected within a large prospective epidemiological study and included a formal assessment by one of five research speech and language therapists as well as a parental report of their child's voice. Common risk factors that were also analyzed included sex, sibling numbers, asthma, regular conductive hearing loss, and frequent upper respiratory infection. The research clinicians identified a dysphonia prevalence of 6% compared with a parental report of 11%. Both measures suggested a significant risk of dysphonia for children with older siblings. Other measures were not in agreement between clinician and parental reports. The clinician judgments also suggested significant risk factors for sex (male) but not for any common respiratory or otolaryngological conditions that were analyzed. Parental report suggested significant risk factors with respect to asthma and tonsillectomy. These results are discussed in detail.     

HL-2M 装置集成安装进度控制研究

大型托卡马克装置集成安装工程子项多、接口繁多、工作空间狭小、系统复杂、参与人员众多,如 何做好装置集成安装的进度控制至关重要。基于工程进度风险管理思维,详细分析了 HL-2M 装置集成安装进度 控制风险因素,并探索了进度控制体系有效运行方式,为安装进度风险可控且实现进度控制目标提供了保障,也 为我国大型磁约束核聚变装置集成安装标准化和规模化发展积累了经验。     

HL-2M 装置极向场线圈的结构设计与制造

介绍了 HL-2M 装置极向场(PF)线圈的结构设计和制造。16 饼 PF 线圈布置在环向场(TF)线圈空腔之 内、真空室外,沿中平面对称分布。PF 线圈采用中空矩形铜导体绕制,其中 PF1~PF4 线圈为双层螺旋绕制结构, 最大运行电流 14.5kA;PF5~PF8 线圈为多层盘式绕制结构,最大运行电流 38~42kA。      

300MVA 脉冲发电机高压变频器调速装置设计及调试

HL-2M 装置 300MVA 脉冲发电机组的调速装置高压变频器主要由输入和输出部分、功率单元、控 制部分组成。对高压变频器进行了调试及试验运行。试验表明其输入谐波含量小,输出波形也是完美正弦波,启 动到工作转速的时间为 16min,再加速时间未超过 5min,能够满足实验放电要求。根据调试情况对空载电流及转 子时间常数进行了优化,在空载电流为 300A、转子时间常数为 1.34s 时,其性能为最优。     

Parallel Correlation Studies of Fluctuations and the Impact of Perturbations in the Magnetic Configuration

The plasma turbulence in the boundary of fusion relevant experiments is known to have a quasi two‐dimensional nature: the scale lengths perpendicular to the magnetic field are in the order of mm to cm, but parallel to the magnetic field, the correlation lengths are in the order of several meters. Recent parallel correlation studies with Langmuir probes at the JET tokamak over very long connection lengths (23 m and 66 m probe tip separation along the magnetic field) showed a correlation of less than 50%, in contrast to the finding of 80–90% correlation in other devices at measurements with smaller probe tip separations. However, it was not clear if this is a genuine physical property of the electrostatic turbulence in the scrape‐off layer or whether perturbations in the magnetic configuration had caused an additional decorrelation by a time‐dependent misalignment of the two probe tips along the connecting field line. In this contribution we analyze the effect of such perturbations in the magnetic configuration on the parallel correlation measurements in a simple model and compare the results with those of the measurements at JET.     

Biochemical and Biophysical Characterisation of the Hepatitis E Virus Guanine-7-Methyltransferase

Hepatitis E virus (HEV) is an understudied pathogen that causes infection through fecal contaminated drinking water and is prominently found in South Asian countries. The virus affects ~20 million people annually, leading to ~60,000 infections per year. The positive-stranded RNA genome of the HEV genotype 1 has four conserved open reading frames (ORFs), of which ORF1 encodes a polyprotein of 180 kDa in size, which is processed into four non-structural enzymes: methyltransferase (MTase), papain-like cysteine protease, RNA-dependent RNA polymerase, and RNA helicase. MTase is known to methylate guanosine triphosphate at the 5′-end of viral RNA, thereby preventing its degradation by host nucleases. In the present study, we cloned, expressed, and purified MTase spanning 33–353 amino acids of HEV genotype 1. The activity of the purified enzyme and the conformational changes were established through biochemical and biophysical studies. The binding affinity of MTase with magnesium ions (Mg²⁺) was studied by isothermal calorimetry (ITC), microscale thermophoresis (MST), far-UV CD analysis and, fluorescence quenching. In summary, a short stretch of nucleotides has been cloned, coding for the HEV MTase of 37 kDa, which binds Mg²⁺ and modulate its activity. The chelation of magnesium reversed the changes, confirming its role in enzyme activity.     

Edge operational regimes in tokamaks

Edge operational regimes in tokamaks are described using mostly experimental results of ASDEX Upgrade. Emphasis is put on high confinement mode (H-mode) at medium and high densities up to the density limit. Implications for the physics of H-mode and the density limit are discussed.     

Kinetics and mechanism of oxidations by metal ions. Part 16. Oxidation of 4-oxopentanoic acid by aquomanganese(III) ions

Summary The outer-sphere oxidation of 4-oxopentanoic acid (4-OPA) to MeCO₂H by aquomanganese(III) ions exhibits a first-order dependence on [4-OPA] and [Mn(III)](aq). The observed pseudo first-order rate constant k _obs ([4-OPA] [Mn^III](aq)) is independent of [Mn^II] but decreases with increasing [H⁺]. The retarding effect of [H⁺] on the observed rate could be explained by considering either the reaction between MnOH⁺(aq) and MeCOCH₂— CH₂CO₂H or between Mn³⁺(aq) and MeCOCH₂CH₂-COO^– ions. The rate constant for the latter pair of reactants is much higher than the rate constant for the reaction between the first pair. Since the activation enthalpy for the first pair is about 14 kJ mol^–1 less than that of the second pair, it is concluded that the reactive species are MnOH²⁺(aq) and MeCOCH₂CH₂CO₂H or that the preferred oxidant is MnOH²⁺(aq) ion.     

Absorption and emission of light in red emissive carbon nanodots

The structure–function relationship, especially the origin of absorption and emission of light in carbon nanodots (CNDs), has baffled scientists. The multilevel complexity arises due to the large number of by-products synthesized during the bottom-up approach. By performing systematic purification and characterization, we reveal the presence of a molecular fluorophore, quinoxalino[2,3-b]phenazine-2,3-diamine (QXPDA), in a large amount (∼80% of the total mass) in red emissive CNDs synthesized from o-phenylenediamine (OPDA), which is one of the well-known precursor molecules used for CND synthesis. The recorded NMR and mass spectra tentatively confirm the structure of QXPDA. The close resemblance of the experimental vibronic progression and the mirror symmetry of the absorption and emission spectra with the theoretically simulated spectra confirm an extended conjugated structure of QXPDA. Interestingly, QXPDA dictates the complete emission characteristics of the CNDs; in particular, it showed a striking similarity of its excitation independent emission spectra with that of the original synthesized red emissive CND solution. On the other hand, the CND like structure with a typical size of ∼4 nm was observed under a transmission electron microscope for a blue emissive species, which showed both excitation dependent and independent emission spectra. Interestingly, Raman spectroscopic data showed the similarity between QXPDA and the dot structure thus suggesting the formation of the QXPDA aggregated core structure in CNDs. We further demonstrated the parallelism in trends of absorption and emission of light from a few other red emissive CNDs, which were synthesized using different experimental conditions.

Herein we unveil the presence of a molecular fluorophore quinoxalino[2,3-b]phenazine-2,3-diamine (QXPDA) in a colossal amount in red emissive CNDs synthesized from o-phenylenediamine, a well-known precursor molecule used for CND synthesis.