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We report on a vortex laser chirped-pulse amplification (CPA) system that delivers pulses with a peak power of 45 TW. A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme. Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser, an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system, and achieve high-power amplification with a series of amplifiers. This method is low cost and can be easily implemented in an existing laser system. The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system, which has important potential applications in strong-field laser physics, for example, generation of vortex particle beams with orbital angular momentum, fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.
Chest tube drainage placement, a standard procedure in video-assisted thoracoscopic surgery, was reported to cause perioperative complications like pain and increased risk of infection. The present study was designed to evaluate the necessity of chest tube drainage inpaediatric thoracoscopic surgery.
Thirty children admitted to our hospital from April 2018 to April 2020 were included in the current study and were grouped as the tube group (children receiving video-assisted thoracoscopic surgery with chest tube drainage) and the non-tube group (children receiving video-assisted thoracoscopic surgery without chest tube drainage). Laboratory hemogram index, length of hospitalisation, post-operative performance of involved children, and psychological acceptance of indicated therapy by guardians of the involved children were investigated.
Laboratory examination revealed that the mean corpuscular haemoglobin concentration in the non-tube group was significantly higher than that in the tube group on post-operative day 1 (p < 0.05). Children in the non-tube group had a shorter length of hospitalisation (7–9 days) than that of patients from the tube group. Additionally, the frequency of crying of children was decreased and psychological acceptance by patients’ guardians was improved in the non-tube group when compared with the tube group.
This study showed that chest tube drainage placement may not be necessary in several cases of paediatric video-assisted thoracoscopic surgery. Rapid recovery with decreased perioperative complications in children operated by video-assisted thoracoscopic surgery without tube placement could also reduce the burden of the family and society both economically and psychologically.
In this article, the electron trapping and acceleration in the wake field driven by an ultrarelativistic hollow electron beam is studied. When the hollow driver injects into plasma, there is a doughnut-shaped electron bubble formed because of the existence of a special ‘backflow’ beam in the centre of the electron bubble. At the same time, there is a transverse convergence of the hollow driver, which leads to the weakening of the backflow beam. This results in a local electron density transition at the rear of the bubble. During this process, there is an expansion of the longitudinal electron bubble size, and a bunch of background electrons is trapped by the wake field at the rear of the bubble. The tracks for the trapped electrons show that there are two sources: one is from the bubble sheath and the other is from the unique backflow beam. In the particle-in-cell simulation where the driving beam has initial energy of $1.0$ GeV per particle, the trapped beam can be accelerated to energy of more than $1.5$ GeV per particle and the corresponding transformer ratio is $1.5$. With the increase of driving beam energy up to $40.0$ GeV, a transformer ratio of $1.4$ still can be achieved. By adjusting the hollow beam density, it is possible to control the trapped beam charge value and beam quality, such as its energy spread and transverse emittance.
One of the leading challenges in chemical sciences is the separation of complex mixtures. This is of vital importance for areas such as commodity chemical generation, where there is a need for the generation of high-purity chemical streams. Due to this, there has been a strong push toward the investigation of new materials capable of achieving chemoselective separation, with self-assembled materials having shown a great deal of promise for such separations. Many self-assembled materials are desirable candidates due to their low-cost synthesis, structural self-regulation, tunable properties, and an overall ease of composite material preparation. In this article, we aim to introduce examples of novel self-assembled materials and their practical usage in chemical separations. The specific approaches to fabricate these materials, as well as the strengths and shortcomings associated with their structures, will also be described. The strategies presented here will emphasize the production and employment of nonconventional self-assembled materials that exhibit a high potential for the advancement of the science of chemical separations.
Data on average iodine requirements for the Chinese population are limited following implementation of long-term universal salt iodisation. We explored the minimum iodine requirements of young adults in China using a balance experiment and the ‘iodine overflow’ hypothesis proposed by our team. Sixty healthy young adults were enrolled to consume a sequential experimental diet containing low, medium and high levels of iodine (about 20, 40 and 60 μg/d, respectively). Each dose was consumed for 4 d, and daily iodine intake, excretion and retention were assessed. All participants were in negative iodine balance throughout the study. Iodine intake, excretion and retention differed among the three iodine levels (P < 0·01 for all groups). The zero-iodine balance derived from a random effect model indicated a mean iodine intake of 102 μg/d, but poor correlation coefficients between observed and predicted iodine excretion (r 0·538 for μg/d data) and retention (r 0·304 for μg/d data). As iodine intake increased from medium to high, all of the increased iodine was excreted (‘overflow’) through urine and faeces by males, and 89·5 % was excreted by females. Although the high iodine level (63·4 μg/d) might be adequate in males, the corresponding level of 61·6 μg/d in females did not meet optimal requirements. Our findings indicate that a daily iodine intake of approximately half the current recommended nutrient intake (120 μg/d) may satisfy the minimum iodine requirements of young male adults in China, while a similar level is insufficient for females based on the ‘iodine overflow’ hypothesis.
To improve the corrosion resistance and to increase the hardness of copper substrate in marine environment, the Cu-Ni/Ni-P composite coatings were prepared on the copper substrate using the galvanostatic electrolytic deposition method. The deposition current densities were explored to find the optimized deposition conditions for forming the composite coatings. Corrosion resistance properties were analyzed using the polarization curves and electrochemical impedance spectroscopy (EIS). Considering the corrosion resistance and hardness, the −20 mA/cm2 was selected to deposit Cu-Ni coatings on copper substrate and the −30 mA/cm2 was selected to deposit Ni-P coating on the Cu-Ni layer. The Cu-Ni/Ni-P composite coatings not only exhibited superior corrosion resistance compared to single Cu-Ni coating in 3.5 wt.% NaCl solution, but also showed much better mechanical properties than single Cu-Ni coating.
The aim of the current meta-analysis was to evaluate the accuracy of using BMI based on self-reported height and weight (BMIsr) to estimate the prevalence of overweight and obesity among children and adolescents.
A systematic literature search was conducted to select studies that compared the prevalence rates of overweight and obesity based on BMIsr and BMIm (BMI based on measured height and weight). A random-effect model was assumed to estimate summary prevalence rates and prevalence ratio (PR).
Thirty-seven studies were included. The aggregated prevalence of overweight and obesity based on BMIsr (0·190, 95 % CI 0·163, 0·221) was significantly lower than that based on BMIm (0·233, 95 % CI 0·203, 0·265). The pooled mean PR was 0·823 (95 % CI 0·775, 0·875). Moderator analyses showed that the underestimation was related to gender, age, weight status screened (overweight v. obesity) and weight status screening tool.
BMIsr may produce less biased results under some conditions than others. Future researchers using BMIsr may consider these findings and avoid the conditions that could lead to more severe underestimation of the prevalence of overweight and obesity among children and adolescents.
Many previous studies have investigated the late Palaeozoic ophiolites, migmatites and high-pressure metamorphic belts of the Tibetan Plateau, whereas the early Palaeozoic evolution of the regions is relatively poorly understood. Lower Palaeozoic strata, including the Duguer quartz schist, occur in the Himalaya, Lhasa and South Qiangtang terranes of the Tibetan Plateau. In this study, we report the depositional age and sedimentary provenance of the Duguer quartz schist of the central South Qiangtang terrane, which enables us to interpret the tectonic affinity of the terrane. We obtained U–Pb ages, trace-element compositions and Hf isotopic data from zircons from the Duguer quartz schist. A total of 162 U–Pb analyses of detrital zircons from the schist yielded two pronounced age peaks at c. 600 Ma and c. 960 Ma. These results indicate that the provenance of the Duguer quartz schist is India Gondwana or the terranes that share an affinity with India Gondwana in the Tibetan Plateau, which include the South Qiangtang and Himalaya terranes. Detrital zircon crystals show large variations in Hf isotope compositions, with εHf(t), TDM and TDMC values of −52.5 to 13.2, 900–3300 Ma and 1010–4240 Ma, respectively. This suggests that the source area for the Duguer quartz schist included Precambrian rocks and, more specifically, Pan-African and Grenville–Jinning crustal material. During Pan-African and Grenville–Jinning events, crustal recycling and the addition of mantle material occurred in the source regions of the quartz schist, when the South Qiangtang, Lhasa and Himalaya terranes were all part of the northern margin of Gondwana.
The bioavailability of dietary ionised calcium is affected by intestinal basic environment. Calcium-binding peptides can form complexes with calcium to improve its absorption and bioavailability. The aim of this study was focused on isolation and characterisation of a calcium-binding peptide from whey protein hydrolysates. Whey protein was hydrolysed using Flavourzyme and Protamex with substrate to enzyme ratio of 25 : 1 (w/w) at 49 °C for 7 h. The calcium-binding peptide was isolated by DEAE anion-exchange chromatography, Sephadex G-25 gel filtration and reversed phase high-performance liquid chromatography (RP-HPLC). A purified peptide of molecular mass 204 Da with strong calcium binding ability was identified on chromatography/electrospray ionisation (LC/ESI) tandem mass spectrum to be Glu-Gly (EG) after analysis and alignment in database. The calcium binding capacity of EG reached 67·81 μg/mg, and the amount increased by 95% compared with whey protein hydrolysate complex. The UV and infrared spectrometer analysis demonstrated that the principal sites of calcium-binding corresponded to the carboxyl groups and carbonyl groups of glutamic acid. In addition, the amino group and peptide amino are also the related groups in the interaction between EG and calcium ion. Meanwhile, the sequestered calcium percentage experiment has proved that EG-Ca is significantly more stable than CaCl2 in human gastrointestinal tract in vitro. The findings suggest that the purified dipeptide has the potential to be used as ion-binding ingredient in dietary supplements.
Growing evidence shows that the deregulation of the circadian clock plays an important role in the development of malignant tumors, including gliomas. However, the molecular mechanisms of genes controlling circadian rhythm in glioma cells have not been explored.
Using reverse transcription polymerase chain reaction and immunohistochemistry techniques, we examined the expression of two important clock genes, Per1 and Per2, in 33 gliomas.
In this study, out of 33 gliomas, 28 were Per1-positive, and 23 were Per2-positive. The expression levels of Per1 and Per2 in glioma cells were significantly different from the surrounding non-glioma cells (P<0.01). The difference in the expression rate of Per1 and Per2 in high-grade (grade III and IV) and low-grade (grade 1 and II) gliomas was insignificant (P>0.05). While there was no difference in the intensity of immunoactivity for Per2 between high-grade gliomas and low-grade gliomas (r=-0.330, P=0.061), the expression level of Per1 in highgrade gliomas was significantly lower than that in low-grade gliomas(r=-0.433, P=0.012).
In this study, we found that the expression of Per1 and Per2 in glioma cells was much lower than in the surrounding non-glioma cells. Therefore, we suggest that disturbances in Per1 and Per2 expression may result in the disruption of the control of normal circadian rhythm, thus benefiting the survival of glioma cells. Differential expression of circadian clock genes in glioma and non-glioma cells may provide a molecular basis for the chemotherapy of gliomas.
In this work, we reported the optical photometry monitoring results for two brightest nearby quasars, PHL 1811 and 3C 273 using the ST-6 camera at Abastumani Observatory, Georgia. For PHL 1811, we found 3 microvariability events with time scale of ΔT = 6.0 min. For 3C273, we found that the largest variations are ΔV = 0.369 ± 0.028 mag, ΔR = 0.495 ± 0.076 mag, and ΔI = 0.355 ± 0.009 mag. When periodicity analysis methods are adopted to the available data, a period of p = 5.80 ± 1.12 years is obtained for PHL 1811, and p = 21.10 ± 0.14, 10.00 ± 0.14, 7.30 ± 0.09, 13.20 ± 0.09, 2.10 ± 0.06, and 0.68 ± 0.05 years are obtained for 3C 273.
Variability is one of the extreme observational properties of BL Lacertae objects. AO 0235+164 is a well studied BL Lac through the whole electro-magnetic wavebands, it is violently variable in the optical bands. In the present work, we show its optical R band photometric observations carried out during the period of Nov. 2006 to Dec. 2012 using the Ap6E CCD camera attached to the primary focus of the 70 cm meniscus telescope at Abastumani Observatory, Georgia. It shows a large variation of ΔR = 4.88 mag (14.20 - 19.08 mag) during our monitoring period. When periodicity analysis methods are adopted to its R observations from our Abastumani monitoring programme and those in the literature, the signs of some periods, P1 = 8.26 yr, P2 = 0.55 yr, P3 = 0.85 yr, P4 = 1.99 yr are found.
In this talk, we will show the beaming effect for Fermi/LAT blazars, then we discuss the correlations between γ-ray luminosity and other parameters, such as radio Doppler factors, superluminal motions, and core-dominance parameters. We also compare the Doppler factors determined from the γ-ray luminosity, X-ray emissions, and the short-term time scales with those from other methods. Our discussions suggest that γ-ray emissions may be strongly beamed.
We develop the dimension-reduced hyperbolic moment method for the Boltzmann equation, to improve solution efficiency using a numerical regularized moment method for problems with low-dimensional macroscopic variables and high-dimensional microscopic variables. In the present work, we deduce the globally hyperbolic moment equations for the dimension-reduced Boltzmann equation based on the Hermite expansion and a globally hyperbolic regularization. The numbers of Maxwell boundary condition required for well-posedness are studied. The numerical scheme is then developed and an improved projection algorithm between two different Hermite expansion spaces is developed. By solving several benchmark problems, we validate the method developed and demonstrate the significant efficiency improvement by dimension-reduction.
This letter focuses on the evolution under illumination of the minority carrier lifetime and conversion efficiency of p-type gallium (Ga) co-doped solar grade multicrystalline silicon wafers and solar cells. We present experimental data regarding the concentration of boron-oxygen (B-O) defects in this silicon when subjected to illumination, and the concentration was found to depend on [B]-[P] rather than [B] or the net doping p0([B] + [Ga] – [P]). This result implies that the compensated B is unable to form the B-O defect. Minority carrier lifetime and EQE measurements at different degradation states indicate that the B-O defect and Fe-acceptor pairs are the two key centers contributed to LID in this material.
Spermatogonial stem cells (SSCs) have the ability to self-renew and offer a pathway for genetic engineering of the male germ line. Cryopreservation of SSCs has potential value for the treatment of male infertility, spermatogonial transplantation, and so on. In order to investigate the cryopreservation effects of different cryoprotectants on murine SSCs, 0.2 M of low-density lipoproteins (LDL), trehalose and soybean lecithin were added to the cryoprotective medium, respectively, and the murine SSCs were frozen at −80°C or −196°C. The results indicated that the optimal recovery rates of murine SSCs in the cryoprotective medium supplemented with LDL, trehalose and soybean lecithin were 92.53, 76.35 and 75.48% at −80°C, respectively. Compared with freezing at −196°C, the optimum temperature for improvement of recovery rates of frozen murine SSCs, cryopreservation in three different cryoprotectants at −80°C, were 17.11, 6.68 and 10.44% respectively. The recovery rates of murine SSCs in the cryoprotective medium supplemented with 0.2 M LDL were significantly higher than that of other cryoprotectants (P < 0.05). Moreover, the recovery rates were demonstrated to be greater at −80°C compared with at −196°C (P < 0.05). In conclusion, 0.2 M of LDL could significantly protect murine SSCs at −80°C. In the freezing–thawing process, LDL is responsible for the cryopreservation of murine SSCs because it can form a protective film at the surface of membranes. However, more research is needed to evaluate and understand the precise role of LDL during the freezing–thawing of SSCs.
The study of interactions between a high-power laser and atoms has been one of the fundamental and interesting topics in strong field physics for decades. Based on a nonperturbative model, ten years ago, we developed a set of programs to facilitate the study of interactions between a circularly polarized laser and atomic hydrogen. These programs included only contribution from the bound states of the hydrogen atom. However, as the laser intensity increases, contribution from continuum states to the excitation and ionization processes becomes larger and can no longer be neglected. Furthermore, because the original code is not able to add this contribution directly due to its many disadvantages, a major upgrade of the code is required before including the contribution from continuum states in future. In this paper, first we deduce some important formulas for contribution of continuum states and present modifications and tests for the upgraded code in detail. Second we show some comparisons among new results, old results from the original codes and the available experimental data. Overall the new result agrees with experimental data well. Last we present our calculation of above-threshold ionization (ATI) rate and compare it with a pertuba-tive calculation. The comparison shows that our nonperturbative calculation can also produce ATI peak suppression.
A real-time fluorescent polymerase chain reaction (PCR) assay was established to detect Streptococcus suis serotype 2. Primers and Taqman probe were designed according to cps2I (capsular polysaccharide 2I) gene using bio-software Primer Express2.0 and Oligo6.0. An 81 bp DNA fragment was amplified from S. suis serotype 2 genomic DNA, and the PCR product was cloned into pMD18-T vector and confirmed by DNA sequencing. The real-time fluorescent PCR amplification curve on a Lightcycler® showed that the method is accurate and specific for S. suis serotype 2 amplification, whereas reference bacteria S. suis, Escherichia coli, Salmonella sp., Staphylococcus aureus, Shigella sp., Listeria monocytogenes strains and a blank control were all negative. Tenfold serial dilutions of S. suis serotype 2 were used to measure the sensitivity of real-time fluorescent PCR: ten copies of bacteria could be detected in one PCR reaction and only 30 min were required for a single test. To examine the stability of the real-time fluorescent PCR, the positive control was detected at two different times. The threshold cycle (Ct) values showed no statistical differences (P>0.05). Thus, this method was stable and repeatable. These results indicate that this real-time fluorescent PCR technique could be applied for epidemic supervision in entry–exit inspection and quarantine.
Casein phosphopeptide amorphous calcium phosphate nanocomplexes (CPP-ACP) in chewing gum, lozenges and mouthrinses have been shown to remineralize enamel subsurface lesions in human in situ experiments. The aim of this double-blind, randomized clinical study was to investigate the capacity of CPP-ACP added to bovine milk to remineralize enamel subsurface lesions in situ. Ten subjects drank milk containing either 2·0 or 5·0 g CPP-ACP/l or a control milk whilst wearing removable appliances with enamel slabs containing subsurface demineralized lesions. Each 200 ml milk sample was consumed once a day for each weekday over three consecutive weeks. After each treatment and one weeks rest the subjects crossed over to the other treatments. At the completion of the treatments the enamel slabs were removed and remineralization determined using microradiography and microdensitometry. The results demonstrated that all three milk samples remineralized enamel subsurface lesions. However, the milk samples containing CPP-ACP produced significantly greater remineralization than the control milk. The remineralising effect of CPP-ACP in milk was dose-dependent with 2·0 and 5·0 g CPP-ACP/l producing an increase in mineral content of 70 and 148%, respectively, relative to the control milk. The differences in remineralization following exposure to the three milk samples were all statistically significant (P<0·001). In conclusion, this study shows that the addition of 2·0–5·0 g CPP-ACP/l to milk substantially increases its ability to remineralize enamel subsurface lesions.