Mechanism studies for relativistic attosecond electron bunches from laser-illuminated nanotargets.

To find a way to control the electron-bunching process and the bunch-emitting directions when an ultraintense, linearly polarized laser pulse interacts with a nanoscale target, we explored the mechanisms for the periodical generation of relativistic attosecond electron bunches. By comparing the simulation results of three different target geometries, the results show that for nanofoil target, limiting the transverse target size to a small value and increasing the longitudinal size to a certain extent is an effective way to improve the total electron quantity in a single bunch. Then the subfemtosecond electronic dynamics when an ultrashort ultraintense laser grazing propagates along a nanofoil target was analyzed through particle-in-cell simulations and semiclassical analyses, which shows the detailed dynamics of the electron acceleration, radiation, and bunching process in the laser field. The analyses also show that the charge separation field produced by the ions plays a key role in the generation of electron bunches, which can be used to control the quantity of the corresponding attosecond radiation bunches by adjusting the length of the nanofoil target.

High-Flux Neutron Generator Based on Laser-Driven Collisionless Shock Acceleration.

A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield 6.6×10^{7} n/sr from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is 10^{19} W/cm^{2}. Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to 5×10^{10} n/sr can be obtained when laser intensity increases to 10^{21} W/cm^{2} under the same laser energy.

Efficient high-charge Laguerre-Gaussian mode conversion by using a periscopic axicon mirror.

Laguerre-Gaussian (LG) modes can be converted from fundamental Gaussian mode by using phase optical elements such as spiral phase plates (SPP), but the conversion efficiency is strongly reduced in high charge plates because of the transverse intensity deviation. In this paper, a three-step scheme is proposed to dramatically improve the conversion efficiency. First, a fundamental Gaussian beam is converted to a 1st-order LG beam via a 1st-order SPP and a spatial filtering system. Then, by using a periscopic axicon mirror (PAM), the lst-order LG beam is transformed into an annular beam with larger beam radius. Finally, by using a second high-order SPP, this intensity-matched ring beam can be effectively converted to a high-charge LG0l beam. Through optimization of the PAM's parameter, the total conversion efficiency from fundamental Gaussian beam to LG0l mode as high as 91.85% is obtained, which is much higher than the case without PAM. Numerical simulations are carried out by the particle-in-cell (PIC) code EPOCH to verify the effectiveness of the scheme.

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.

[Homosexual behavior and related factors among married men who have sex with men in Mianyang city, Sichuan province].

Objective: To understand the homosexual behavior and related factors among married MSM in Mianyang city. Methods: Between January and October in 2017, a snowball sampling method was adopted to carry out cross-sectional survey through questionnaires plus HIV testing among those MSM in Mianyang city. Logistic regression model was used to analyze homosexual behaviors and related factors among married MSM under study. Statistical analysis was used by EpiData 3.1 and SPSS 19.0 software. Results: A total of 234 MSM participated in this survey. The overall rate of homosexual behavior in these married MSM appeared as 94.9% (222/234). Rate of having anal sex behavior was 94.4% (221/234) in the past 6 months, with rate of condom use as 57.9% (128/221). HIV positive rate was 8.1% (18/222). As for the motives for homosexual behavior after marriage, 87.8% (195/222) were driven by feelings of love, 12.2% (27/222) due to 'releasing pressure'. Proportion of male sex partners would include occasional sex partners (62.2%, 138/222), stable male sex partners (26.1%, 58/222) and stable boyfriends (11.7%, 26/222). Factors from logistic regression analysis showed that homosexual behaviors were related to the factors including education level of senior high school or above vs. education level of junior middle school or below (OR=3.65, 95%CI: 1.33-9.98); local residency over one year vs. the ones having local residency less than one year (OR=23.28, 95%CI:1.67-324.89); having 10 or more friends in the MSM community vs. having below 10 friends in MSM community (OR=4.15, 95%CI: 1.28-13.43); without sex pleasure with spouse vs. having sex pleasure with spouse (OR=3.25, 95%CI: 1.22-8.62); having 2 or more anal sex partners in the past 6 months vs. having less than 2 anal sex partners in the past 6 months (OR=0.28,95%CI: 0.09-0.81). Conclusions: The rate of homosexual behavior and HIV positive rate were high among MSM in Mianyang city. Homosexual behaviors after marriage were influenced by multiple factors among MSM. The motives of homosexual behavior after marriage were driven by feelings of love, the related factors were education level of senior high school or above, local residency over one year, having 10 or more friends in the MSM community and without sex pleasure with spouse. As for the motives of these behaviors was caused by releasing pressure, the related factors was having more than 2 anal sex partners.

Towards high-energy, high-resolution computed tomography via a laser driven micro-spot gamma-ray source.

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 µm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

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.

Effects of lipopeptide carboxymethyl chitosan nanoparticles on Staphylococcus aureus biofilm.

This study aims to evaluate the effect of lipopeptide carboxymethyl chitosan nanoparticles on Staphylococcus aureus biofilm as part of the development of a new anti-biofilm material. The study had three stages. Firstly, we assessed the Staphylococcus aureus capability to form biofilm and enumerated the number of attached bacteria and free bacteria; secondly, we determined the inhibitory effect of different concentrations of Bacillus natto antimicrobial lipopeptid- carboxymethyl chitosan (BNAP-CMCS) nanoparticles added at different times on biofilm formation capability and the numbers of free bacteria and attached bacteria. Lastly, we tested the scavenging effect of BNAP-CMCS nanoparticles on biofilm formation and number of attached bacteria. The results showed that the amount of attached bacteria quickly increased over time and reached the maximum after 24 h of culture. The BNAP-CMCS nanoparticles had the greatest effect on biofilm inhibition at the concentration of 1 MIC, after 8 h of culture, and the effect was dose-dependent. The BNAP-CMCS nanoparticles had decreased also the numbers of free and attached bacteria in a dose-dependent fashion, after 8 hours of culture. The scavenging effect of BNAP-CMCS nanoparticles on free and attached bacteria was maximum at 6 MIC. In conclusion, lipopeptide carboxymethyl chitosan nanoparticles had a good inhibition and scavenging effect on the formation of Staphylococcus aureus biofilm and the growth of surface-attached bacteria.

[Cancer-associated-fibroblasts regulate the chemoresistance of lung cancer cell line A549 via SDF-1 secretion].

Objective: To investigate whether cancer-associated- fibroblasts (CAF), the key component of tumor microenvironment, regulate the chemoresistant capacity of lung cancer cell line A549 through SDF-1 secretion. Methods: Primary cell isolation techniques was used to isolate cancer-associated-fibroblasts from lung cancer patients. MTT assay was applied to determine the proliferation and chemoresistance of A549 cells. Quantative PCR was used to detect the mRNA changes of Bcl-xL. Western blotting was used to detect the protein expression of Bcl-xL. ELISA was applied to detect the SDF-1 secretion from normal fibroblasts (NF) and CAF. Results: CAF promoted the proliferation of A549 cells, while NF had no significant effect on them. After 72 hrs incubation, the absorbance value of A549+ CAF medium group was 0.814±0.006, significantly different from the 0.753±0.006 of the A549+ NF medium group (P<0.05). The Q-PCR assay indicated that mRNA expressions of Bcl-xL in the A549 group, A549+ NF medium group and A549+ CAF medium group were 1.00±0.11, 1.10±0.09 and 3.50±0.30, respectively, showing a significant difference between the A549+ NF medium group and A549+ CAF medium group (P<0.05). The Western blot showed that protein expressions of Bcl-xL in the A549 group, A549+ NF medium group and A549+ CAF medium group were 1.00±0.08, 1.10±0.12 and 3.10±0.25, respectively, with a significant difference between the A549+ NF medium group and A549+ CAF medium group (P<0.05). The ELISA results showed that the SDF-1 concentrations in the A549+ NF medium group and A549+ CAF medium group were 3.23±0.02 and 9.53±0.10, respectively, significantly different from each other (P<0.05). The MTT assay indicated that the absorbance values of OD of A549 group, A549+ AMD3100 group, A549+ NF medium group, A549+ NF medium+ AMD3100 group, A549+ CAF medium and A549+ CA Fmedium+ AMD3100 group were 0.43±0.03, 0.25±0.02, 0.48±0.03, 0.31±0.03, 0.72±0.06 and 0.45±0.03, respectively. The data of A549+ NF medium group was significantly different from that of A549+ CAF medium group (P<0.05). Conclusions: Cancer-associated-fibroblasts enhance the drug resistance of A549 cells through SDF-1 secretion, upregulating the expression level of Bcl-xL through interaction with CXCR4. Our study not only illustrates that tumor microenvironment is able to enhance drug resistance of tumor, but also provides experimental evidence for the cancer-associated-fibroblasts as a potential therapeutic target for the treatment of lung cancer.

MHC haplotypic association in Chinese Han patients with vitiligo.

BACKGROUND: Serological typing of the human leucocyte antigen (HLA) has shown discrepancies in HLA associations with vitiligo in different ethnic populations. OBJECTIVE: To evaluate the distributions of HLA at class I and II loci that may contribute to the genetic susceptibility of vitiligo patients in Chinese Hans population. METHODS: We analysed the allelic frequencies of HLA class I and II by using the polymerase chain reaction sequence-specific primer (PCR-SSP) method in 187 patients with vitiligo and 273 controls in Chinese Hans. The linkage disequilibrium was calculated from a 2 x 2 table. RESULTS: Two-locus haplotypes including HLA-A25-B13, HLA-A25-B27, HLA-A25-Cw*0602, HLA-A25-DQA1*0302, HLA-A25-DQA1*0601, HLA-A25-DQB1*0303, HLA-B13-Cw*0602, HLA-B13-DQA1*0302, HLA-B13-DQA1*0601, HLA-B27-Cw*0602, HLA-B27-DQA1*0302, HLA-B27-DQA1*0601, HLA-B27-DQB1*0303, HLA-B27-DQB1*0503, HLA-Cw*0602-DQA1*0302, HLA-Cw*0602-DQA1*0601, HLA-Cw*0602-DQB1*0303, HLA-Cw*0602-DQB1*0503 and HLA-DQA1*0302-DQB1*0503 were associated with all types of vitiligo in Chinese Hans. The extended haplotypes HLA-A25-B13-Cw*0602, HLA-A25-B27-Cw*0602, HLA-DQA1*0302-DQB1*0303-Cw*0602 and HLA-B13-DQB1*0303-Cw*0602 were found to be associated with all types of vitiligo in Chinese Hans, whereas the frequency of HLA-A25-Cw*0602-DQA1*0302 was significantly increased in generalized vitiligo but not in localized vitiligo. The frequencies of HLA-A25-DQA1*0302-DQB1*0503 and HLA-A30-DQA1*0302-DQB1*0303 were higher in childhood vitiligo than in adult vitiligo, and the frequency of HLA-A25-B13-DQB1*0303-Cw*0602 was shown to be associated with adult vitiligo but not childhood vitiligo. CONCLUSION: This study demonstrates not only the differential association between HLA markers and types of vitiligo according to distribution or age at onset but also newly found high-risk haplotypes in Chinese vitiligo patients.

Influence of mizolastine on antigen-induced activation of signalling pathways in murine mast cells.

BACKGROUND: There is accumulating evidence that some antihistamines can interrupt intermediate signalling events that regulate cell function. The effect of mizolastine on both the generation and release process of many cytokines in mast cells further implies that the inhibition by mizolastine may target signalling pathways. AIM: To observe the influence of mizolastine on antigen-induced activation of signalling pathways in murine mast cells. METHODS: Western blot analysis and enzyme assay were performed. Immunoblots were prepared from whole cell lysates and probed with antibodies against Fyn, Akt, ERK, p38, phospho-Fyn, phospho-Akt, phospho-ERK and phospho-p38, respectively. RESULTS: Our study showed that signalling molecules such as IP3, Fyn, p38 and ERK were enhanced when mast cells were stimulated by antigen, and that this was not inhibited by treatment with mizolastine. Mizolastine at concentrations from 10(-9) to 10(-5) mol/L could inhibit activation of the PI3K kinase downstream signalling molecule Akt to antigen stimulation. The study also demonstrated that mizolastine exerted inhibitory ability on protein kinase C (PKC) activation in a dose-dependent manner. CONCLUSION: PKC-mediated phosphorylation of Akt can be blocked by mizolastine. There may be a PKC-independent pathway effectively activating MAPK pathways in mast cells in response to antigen induction, which cannot be affected by mizolastine.

Double-peak emission of hot electrons generated by femtosecond laser interaction with solid targets.

Double-peak emission of hot electrons has been observed in the interaction of a 60-fs, 125-mJ, 800-nm, p-polarized laser pulse with Al targets. One peak in the specular direction is due to the reflected laser light, which excites a plasma wave to accelerate electrons. The other peak, which is more consistent with theories of Phys. Plasmas 6, 2855 (1999)] and Phys. Rev. Lett 82, 743 (1999)], is produced by the resonance absorption at approximately 15 degrees from the target normal.

Successful recovery of 14 patients afflicted with full-thickness burns for more than 70 per cent body surface area.

Fourteen cases suffering full-thickness burns of more than 70 per cent total body surface area (TBSA) have been successfully treated during the last 8 years (1988-1995). Among these patients, 10 cases suffered from burns of more than 90 per cent TBSA. Five cases had full-thickness burns of 80-90 per cent TBSA. Escharectomy, followed by coverage of wounds with a homograft to the lower surface of which, adjacent to the wound bed, microautoskin grafts had been attached was employed to close wounds in the early stages after burn. The remaining non-surgically treated wound was treated by exposure and topical silver sulfadiazine. The temperature and humidity of the ward was controlled by air conditioning and dehumidification. Aggressive excision of eschar and auto-skingrafting was carried out 3 weeks post-injury. Strictly limiting the uncovered wound to less than 5 per cent appeared to be the major effective measure in preventing burn infection.

The use of IAA to overcome interspecific hybrid inviability in reciprocal crosses between Nicotiana tabacum L. and N. repanda Willd.

Flowering hybrid plants were obtained from reciprocal crosses between N. tabacum L. (2n=48) and N. repanda Willd. (2n = 48), in which cross incompatibility and hybrid inviability were manifested. Stylar pollination and ovule culture were used to overcome the cross incompatibility of stylar barriers and ovular death. It was shown that application of 2 mg/l indole-3-acetic acid (IAA) during the growth period, from the fiveto six-leaf stage to the flowering stage, is a useful and easy method to overcome hybrid inviability.