[Effect of artesunate on the transplantation tumor of parotid gland in the nude mice with adenoid cystic carcinoma drug resistance cell]

Objective:To observe the effect of Artesunate on the transplantation tumor of parotid gland in the nude mice with adenoid cystic carcinoma drug resistance cell and to explore its clinical application prospect as an anticancer drug.Method:Twenty male BALB/C mice were chose to set up parotid gland transplantation tumor model, then used the method of random Numbers table 20 nude mice were randomly divided into normal saline control group, positive control group DDP 2 mg/kg group, the ART of 200 mg/kg group, ART 100 mg/kg+DDP 1 mg/kg group, a total of 4 groups. Abdominal cavity injection was performed twice a day, and we measured weight of each nude mice and transplantation tumor major axis and minor axis. Treatments were conducted for 4 weeks, then the mice were sacrificed, and tumor weight was measured to calculate the inhibitory rates. The tumors were examined by HE staining to observe each tumor tissue pathological changes and by immunohistochemical method to detect Survivin expression in transplanted tumor tissue. Result:Four weeks after treatments, the inhibitory rate of DDP 2 mg/kg group was 59.86%, but this group of nude mice lost weight obviously； the ART 200 mg/kg group was 43.54%，this group of nude mice had a good mental state, and weight had gaining continuously；the ART 100 mg/kg+DDP 1 mg/kg group was 41.16%, this group of nude mice had reducing weight slightly.HE staining showed:The tumor nuclei were hyperchromatic and shrinkage, nuclear chromatin condensed and cracked into flake in the ART 200 mg/kg group, DDP 2 mg/kg group and the ART 100 mg/kg+DDP 1 mg/kg group. Conclusion:Artesunate can inhibit adenoid cystic carcinoma resistant cells NACC/DDP proliferation in nude mice in vivo and promote its apoptosis, and the side effects of Artesunate on nude mice were lower than Cisplatin.

[The clinical and histopathological analysis of 2 053 cases of conjunctival neoplasms]

Objective: We aimed to identify and describe the clinical and histopathologic characteristics of conjunctival neoplasms. Methods: Retrospective case series study. We collected and analyzed the clinical and histopathologic data of the conjunctival neoplastic specimens including the age, gender, and histopathologic diagnosis of all patients obtained from Beijing Tongren Eye Center between October 2003 and October 2015. All the pathology diagnosis results were divided into two categories which were benign and malignant tumors, according to Shields histopathological classification methods and the pathology diagnosis results in our department. All cases were divided into four groups as 0-17 years old, 18-39 years old, 40-59 years old, aged 60 and above. The chi-square test was used for statistical analysis. Results: Of the 2 053 cases, 1 025 were males and 1 028 were females (male∶female=1∶1). 1660 cases (80.9%) were benign and 393 cases(19.1%) were premalignant or malignant. The average age at diagnosis was 30.5 years for benign lesions and 53.3 years for premalignant and malignant lesions, which was significant different (P<0.01). The most common benign lesions were nevus, cysts, dermoids and dermolipomas, inflammatory granulomas and squamous cell papillomas. The most common premalignant and malignant tumors were CIN, melanomas, lymphomas and squamous cell carcinoma. The constitution of males and females of cysts, squamous cell papillomas, primary acquired melanosis, CIN and lymphomas were significant different (P<0.01). Moreover, the most common benign and malignant neoplasm were dermoids and dermolipomas, melanomas respectively in group under 18 years old. And nevus and lymphomas were the most common benign and malignant tumors respectively in patients between 18 and 39 years old. While cysts and CIN were the most common benign and malignant tumors respectively in cases over 40 years old. Conclusions: The majority of tumors of the conjunctiva were benign, with the young people being most. The premalignant and malignant tumors were more frequent in the elderly. Nevus and CIN were the most common benign and malignant tumors, respectively.(Chin J Ophthalmol, 2016, 52: 738-744).

[Characteristics of retinal and scleral infiltration in uveal melanoma]

Objective: To analyze features of retinal and scleral infiltration of uveal melanoma. Methods: It was a retrospective case series study. The pathological and clinical data of 102 cases of uveal melanoma were analyzed retrospectively, which were collected between Jun. 2001 and Apr. 2013 in Beijing Tongren Hospital, Capital Medical University. The tumor shape, size, cell types, retinal and scleral invasion were recorded and analyzed. The relationship between retinal invasion and scleral invasion was analyzed by trend Chi-square test. Results: There were 44 male patients and 58 female patients with an average age of 45.6±12.4 (range from 15 to 78 years old) in 102 cases. As for tumor size, there were 68 (66.7%) large size tumors, 27 (26.5%) medium size tumors and 7(6.8%) small size tumors; As for cell types, 76 (74.5%) were spindle cell, 6 (5.9%) were epithelioid cell, 16 (15.7%) were mixed cell, and 4 (4.0%) were others; As for tumor location, there were 3 (2.94%) ciliary body melanoma, 28 (27.5%) ciliary body and anterior choroid melanoma, and 71 (69.6%) choroid melanoma. Eighty-six cases (84.3%) showed retinal invasion, in which there were 20 cases of outer nuclear layer invasion (19.6%), 12 cases of inner nuclear layer invasion (11.8%), 30 cases of ganglion cell layer invasion (29.4%), and 24 cases of inner limiting membrane invasion (23.5%). Fifty-five cases (53.9%) showed scleral invasions, in which there were 11 cases (68.8%) of no retinal invasion, 13 cases of outer nuclear layer invasion (65.0%), 5 cases of inner nuclear layer invasion (41.7%), 15 cases of ganglion cell layer invasion (50.0%) and 11 cases of inner limiting membrane invasion (45.8%). In 76 spindle cell cases, the scleral invasion rate of different retinal invasion degree were 72.7% in 8 cases of none retinal invasion, 71.4% in 10 cases of outer nuclear layer invasion, 62.5% in 5 cases of inner nuclear layer invasion, 53.9% in 14 cases of ganglion cell layer invasion and 47.1% in 8 cases of inner limiting membrane invasion. No significant relationship was found between retinal and scleral invasion (γ=-0.21, P=0.127) . Conclusion: With the increase of scleral invasion, the retinal invasion decreased. However, the correlation show no statistical significance.(Chin J Ophthalmol, 2016, 52: 749-754).

[Effect of extent of glottal incompetence on phonation in excised canine larynx models]

Objective: To compare the acoustic signal, mucosal wave and aerodynamic parameter (phonation threshold pressure, PTP) under different sub-glottal pressure (SGP) on the excised canine models with different extent of glottal incompetence. Methods: Perturbation measures and nonlinear dynamic measures were applied to analyze the acoustic signal (jitter, shimmer), mucosal wave [frequency(F), amplitude(A), phase(P)] and PTP from our study including 11 excised canine larynges with different extent of glottal incompetence (0 mm, 1 mm, 2 mm, 3 mm, n=11, respectively) under 1-4 kPa sub-glottal pressure. Results: There were significant differences between different groups in jitter, shimmer, amplitude, frequency and PTP under various SGPs and extent of glottal incompetence (all P<0.05), inversely, there was no significant difference in P between groups (P>0.05). Jitter and shimmer changed obviously when the SGP increased to 3 kPa in the control group and GI 1 mm group. Jitter and shimmer changed obviously when the SGP increased to 2 kPa in the GI 2 mm and 3 mm groups. The F and A of mucosal wave increased with increasing SGP, decreased with increasing GI, and the P changed irregularly. There was statistically significant difference of PTP between different GI groups. Conclusions: The SGP and the extent of GI had obvious affection on the the acoustic signal, mucosal wave and aerodynamic parameters.

Organic nitrogen uptake is a significant contributor to nitrogen economy of subtropical epiphytic bryophytes

Without any root contact with the soil, epiphytic bryophytes must experience and explore poor, patchy, and heterogeneous habitats; while, the nitrogen (N) uptake and use strategies of these organisms remain uncharacterized, which obscures their roles in the N cycle. To investigate the N sources, N preferences, and responses to enhanced N deposition in epiphytic bryophytes, we carried out an in situ manipulation experiment via the (15)N labelling technique in an Asian cloud forest. Epiphytic bryophytes obtained more N from air deposition than from the bark, but the contribution of N from the bark was non-negligible. Glycine accounted for 28.4% to 44.5% of the total N in bryophyte tissue, which implies that organic N might serve as an important N source. Increased N deposition increased the total N uptake, but did not alter the N preference of the epiphytic bryophytes. This study provides sound evidence that epiphytic bryophytes could take up N from the bark and wet deposition in both organic and inorganic N forms. It is thus important to consider organic N and bark N sources, which were usually neglected, when estimating the role of epiphytic bryophytes in N cycling and the impacts of N deposition on epiphytic bryophytes in cloud forests.

Effect of fast pH decline during the early postmortem period on calpain activity and cytoskeletal protein degradation of broiler M. pectoralis major

The objective of this study was to determine the effects of fast pH decline during the early postmortem period on calpain activity and the degradation of cytoskeletal proteins in broilers. Eighty broilers were randomly categorized into two groups: physical restraint (PR) and free struggle (FS). M. pectoralis major (PM) was used for determination of calpain activity, shear value, ultrastructure of myofibrils, and the degradation of desmin, titin, nebulin, and troponin-T. The pH (6.05) of FS group is significantly low than PR group (6.38) at 0.3 h postmortem. Fast pH decline during the early postmortem period led to a decrease of μ/m-calpain activities at 0.3 and 3 h postmortem (P < 0.05), but did not affect the ultimate μ/m-calpain activity. An initial fast decrease in pH increased the degradation of desmin, titin, nebulin, and increased the 30 kDa degradation fragments of troponin-T. Therefore, the fast pH decline during the early postmortem period decreased the μ/m-calpain activity and increased the degradation of cytoskeletal proteins in broiler muscle. It is possible that the fast pH decline experienced an earlier activation of calpains that resulted in earlier protein degradation and ultimately lower shear force.

Nanoscale Electron Bunching in Laser-Triggered Ionization Injection in Plasma Accelerators

Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Because of the phase-dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to a discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three-dimensional effects limit the wave number of the modulation to between >2k_{0} and about 5k_{0}, where k_{0} is the wave number of the injection laser. Such a nanoscale bunched beam can be diagnosed by and used to generate coherent transition radiation and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.

Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

[A study on the X-ray measurement predictors of difficult laryngealexposure in patients undergoing microlaryngosurgery]

Objective:This paper seeks to identify useful and reliable indicators for predicting the occurrence of difficult laryngeal exposure(DLE) in microlaryngosurgery.Method:Sixty-two patients were given physical examinations,including 4 general parameters:age,sex,BMI,and MMI,and 14 physical measurement parameters(TA,UIA,LIA,IG,LIMD,MA,MCD,MH,MDI,HMD,TMD,SMD,TMA,THUIA).Univariate analysis,stepwise regression analysis and ROC curve analysis were employed to identify parameters with the potential to predict DLE.Result:We found sex(P<0.05) showed significant correlation with the laryngeal exposure score(P<0.05).We also found LIMD,MA,TMA and THUIA to be reliable DLE predictors.The cutoff values for predicting DLE were LIMD>4.53cm,MA>115.5°,TMA>99.2°,and THUIA>152.6°.Conclusion:X-ray measurement predictors of LIMD,MA,TMA,and THUIA before operation are important for the prediction of DLE.Sex is also the reliable DLE predictor.Males were prone to DLE.

Insulin in combination with selenium inhibits HG/Pal-induced cardiomyocyte apoptosis by Cbl-b regulating p38MAPK/CBP/Ku70 pathway

OBJECTIVE

In this study, we investigated whether insulin and selenium in combination (In/Se) suppresses cardiomyocyte apoptosis and whether this protection is mediated by Cbl-b regulating p38MAPK/CBP/Ku70 pathway.

MATERIALS AND METHODS

Firstly, H9c2 cardiomyocytes were treatment with high glucose (25 mmol/L) and palmitate (600 μmol/L) (HG/Pal). Next, H9c2 cardiomyocytes were treatment with HG/Pal+In/Se (10 nmol/L Insulin in combination with 10 nmol/L selenium). Finally, cells were treated with siRNA against Cbl-b, followed by HG/Pal and HG/Pal+In/Se treatment. Then, Cell apoptosis was observed by flow cytometry (FCM). The levels of Cbl-b, p-p38MAPK, CBP and Bax were examined by Western blotting. The acetylated Ku70 was detected by immunoprecipitation.

RESULTS

Insulin and selenium in combination reduced cell apoptosis, up-regulated Cbl-b expression, down-regulated p38MAPK, CBP and acetylated Ku70 expressions and prevented Bax translocation, whereas Cbl-b knockdown strongly suppressed In/Se-induced these effects in HG/Pal-treated cardiomyocytes.

CONCLUSIONS

Insulin and selenium synergistically suppressed cardiomyocyte apoptosis by Cbl-b regulating p38MAPK/CBP/Ku70 pathway.

[The role of acoustic analysis of fundamental frequency in differentiating arytenoid dislocation from vocal fold paralysis]

Objective:Analysis of the sustained vowels of acoustic parameters in arytenoid dislocation and vocal fold paralysis. To investigate their acoustic characteristics and evaluate the role of this acoustic analysis method in differentiating arytenoid dislocation from vocal fold paralysis. Method:Thirty-three cases with unilateral vocal cord movement disorders were collected.All cases were divided into arytenoid dislocation group and vocal fold paralysis group through the laryngeal electromyography. Each group was further devided into male group and female group. The voice signals of sustained vowel of /a/ were measured using the software MDVP and obtain the acoustic parameters(Jitter, Shimmer, SPI and Fo). The acoustic characteristics between the two groups were observed and compared. Results were analyzed using Rank sum test for group design.Result:There were significant differences in Fo between arytenoid dislocation group and vocal fold paralysis group in both male and female group（P <0.05）. And mean rank order of Fo in arytenoid dislocation group was greater than vocal fold paralysis group. There were no significant differences in jitter,shimmer and SPI between arytenoid dislocation group and vocal fold paralysis group（P >0.05）.Conclusion:Mean rank order of Fo in arytenoid dislocation group is greater than vocal fold paralysis group in both the male and the female group. Fo is of value in differentiating arytenoid dislocation from vocal fold paralysis. This provides a theoretical basis for the acoustic analysis method to identify these two diseases.

Physics of Phase Space Matching for Staging Plasma and Traditional Accelerator Components Using Longitudinally Tailored Plasma Profiles

Phase space matching between two plasma-based accelerator (PBA) stages and between a PBA and a traditional accelerator component is a critical issue for emittance preservation. The drastic differences of the transverse focusing strengths as the beam propagates between stages and components may lead to a catastrophic emittance growth even when there is a small energy spread. We propose using the linear focusing forces from nonlinear wakes in longitudinally tailored plasma density profiles to control phase space matching between sections with negligible emittance growth. Several profiles are considered and theoretical analysis and particle-in-cell simulations show how these structures may work in four different scenarios. Good agreement between theory and simulation is obtained, and it is found that the adiabatic approximation misses important physics even for long profiles.

Survival and Growth of Epiphytic Ferns Depend on Resource Sharing

Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing) on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets) and another on groups (several ramets within a plot), with severed and intact rhizome treatments (without and with physiological integration) on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium) in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration) significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time.

Effects of Water-misting Sprays with Forced Ventilation after Transport during Summer on Meat Quality, Stress Parameters, Glycolytic Potential and Microstructures of Muscle in Broilers

Effects of water-misting sprays with forced ventilation after transport during summer on meat quality, stress parameters, glycolytic potential and microstructures of muscle in broilers were investigated. A total of 105 mixed-sex Arbor Acres broilers were divided into three treatment groups: i) 45-min transport without rest (T group), ii) 45-min transport with 1-h rest (TR group), iii) 45-min transport with 15-min water-misting sprays with forced ventilation and 45-min rest (TWFR group). The results showed the TWFR group significantly increased (p<0.05) initial muscle pH (pHi) and ultimate pH (pHu) and significantly reduced L* (p<0.05), drip loss, cook loss, creatine kinase, lactate dehydrogenase activity, plasma glucose content, lactate and glycolytic potential when compared with other groups. Microstructure of the muscle from TWFR group broilers under light microscopy showed smaller intercellular spaces among muscle fibers and bundles compared with T group. In conclusion this study indicated water-misting sprays with forced ventilation after transport could relieve the stress caused by transport under high temperature, which was favorable for the broilers' welfare. Furthermore, water-misting sprays with forced ventilation after transport slowed down the postmortem glycolysis rate and inhibited the occurrence of PSE-like meat in broilers. Although rest after transport could also improve the meat quality, the effect was not as significant as water-misting sprays with forced ventilation after transport.

Higher clonal integration in the facultative epiphytic fern Selliguea griffithiana growing in the forest canopy compared with the forest understorey

BACKGROUND AND AIMS

The advantage of clonal integration (resource sharing between connected ramets of clonal plants) varies and a higher degree of integration is expected in more stressful and/or more heterogeneous habitats. Clonal facultative epiphytes occur in both forest canopies (epiphytic habitats) and forest understories (terrestrial habitats). Because environmental conditions, especially water and nutrients, are more stressful and heterogeneous in the canopy than in the understorey, this study hypothesizes that clonal integration is more important for facultative epiphytes in epiphytic habitats than in terrestrial habitats.

METHODS

In a field experiment, an examination was made of the effects of rhizome connection (connected vs. disconnected, i.e. with vs. without clonal integration) on survival and growth of single ramets, both young and old, of the facultative epiphytic rhizomatous fern Selliguea griffithiana (Polypodiaceae) in both epiphytic and terrestrial habitats. In another field experiment, the effects of rhizome connection on performance of ramets were tested in small (10 × 10 cm(2)) and large (20 × 20 cm(2)) plots in both epiphytic and terrestrial habitats.

KEY RESULTS

Rhizome disconnection significantly decreased survival and growth of S. griffithiana in both experiments. The effects of rhizome disconnection on survival of single ramets and on ramet number and growth in plots were greater in epiphytic habitats than in terrestrial habitats.

CONCLUSIONS

Clonal integration contributes greatly to performance of facultative epiphytic ferns, and the effects were more important in forest canopies than in forest understories. The results therefore support the hypothesis that natural selection favours genotypes with a higher degree of integration in more stressful and heterogeneous environments.

The association between BMP4 gene polymorphism and its serum level with the incidence of LVH in hypertensive patients

Background

Bone morphogenic proteins 4 (BMP4) is associated with cardiac remodeling under different conditions. However, the role of BMP4 and its gene polymorphism in the incidence of left ventricular hypertrophy (LVH) in hypertensive patients remains unknown.

Methods

A total of 1265 patients diagnosed with essential hypertension (EH) were recruited. Patients were assigned to LVH+ (n = 420) and LVH- (n = 845) groups. serum BMP4 level was measured and two single nucleotide polymorphism (SNPs) polymorphisms, 6007C > T and -5826G > A of BMP4 gene were genotyped. We also inhibited the BMP4 by small interfering RNA (siRNA). The effect of BMP4 on the hypertrophic response in Human Cardiomyocytes AC16 cells was studied.

Results

We found that the 6007C > T polymorphism of the BMP4 gene and the serum BMP4 level were significantly associated with the risk to develop LVH. With TT as reference, multivariate logistic regression analysis showed the 6007CC genotype carriers had a higher susceptibility to LVH incidence (adjusted OR = 2.65, 95% CI: 1.63-4.31, adjusted P < 0.001). Our in vitro study shows that the BMP4 inhibition in cardiomyocyte by si-RNA technique significantly decreased the Ang II induced cardiomyocyte size and protein content per cell, indicating the importance of BMP4 in the cardiomyocyte hypertrophy.

Conclusion

Collectively, our data suggest that both the 6007C > T of the BMP4 gene and the serum BMP4 level may be used as potential marker for LVH incidence among the EH patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0368-x) contains supplementary material, which is available to authorized users.

The effect of transportation of broilers during summer on the expression of heat shock protein 70, postmortem metabolism and meat quality

The objective of this study was to determine the effects of different transport times on broilers during summer on stress, meat quality, and early postmortem muscle metabolites. Arbor Acres broiler chickens (n = 105) were randomly categorized into 5 treatments: unstressed control, 0.5 h, 1 h, 2 h, and 4 h transport. Each treatment consisted of 3 replicates with 7 birds each. All birds (except the control group) were transported according to a designed protocol. With the extension of transport time, the activities of plasma creatine kinase (CK) and lactate dehydrogenase (LDH) gradually increased. The content of heat shock protein 70 (Hsp70) did not change significantly during 0.5 h transport compared to the control group, but was significantly higher (P < 0.05) at 1 h or more of transport time. Also, transport times of 2 h or more resulted in a death rate of 20%-33% of broilers. We found that the breast meat in the 0.5 h transport group had significantly (P < 0.05) higher L* values, drip loss, cooking loss, AMP/ATP ratio, and phosphorylation of AMP-activated protein kinase (p-AMPK). In addition, pH24h was lower compared to the control group, increasing the likelihood of pale, soft, and exudative (PSE)-like meat. However, no significant variations were found in meat color, drip loss, or cooking loss in other transport groups compared to the control group under the condition of this study. Muscle glycogen content decreased with time of transportation. There were significant correlations among p-AMPK and meat quality (P < 0.05). These results indicate that preslaughter transport during summer may cause severe physiological and biochemical changes of broilers. Further investigations studying the deeper relationship between biological indicators and meat quality according to the similar transport conditions would provide a better understanding of the effect of transport duration on meat quality.

Differential responses of arbuscular mycorrhizal fungi to nitrogen addition in a near pristine Tibetan alpine meadow

Elucidating the responses of soil microbial abundance and community composition to nitrogen (N) addition is important for predicting ecosystem function under increased atmospheric N deposition. We examined the arbuscular mycorrhizal (AM) fungal community under three N forms (NH4(+)-N, NO3(-)-N, and NH4NO3-N) and two N rates (1.5 and 7.5 g N m(-2) year(-1)) in an alpine meadow of the Qinghai-Tibetan Plateau. AM fungal extraradical hyphal density was significantly decreased by NH4(+)-N in May, but was not affected by N form nor N rate in August. N rate, but not N form, significantly affected AM fungal spore density; high N rate decreased spore density. No direct N addition effect was observed on AM fungal community; however, soil available phosphorus, pH, and NO3(-)-N were considered as important factors that influenced AM fungal community composition. Structural equation model results showed that N rate, not N form, strongly affected soil characteristics, which directly influenced community compositions of plants and AM fungi, as well as spore density. Therefore, AM fungal community was influenced by N addition, primarily because of altered soil characteristics, and partially by a modified plant community, but not or just slightly by direct N addition effects in this alpine meadow ecosystem.

Phase-space dynamics of ionization injection in plasma-based accelerators

The evolution of beam phase space in ionization injection into plasma wakefields is studied using theory and particle-in-cell simulations. The injection process involves both longitudinal and transverse phase mixing, leading initially to a rapid emittance growth followed by oscillation, decay, and a slow growth to saturation. An analytic theory for this evolution is presented and verified through particle-in-cell simulations. This theory includes the effects of injection distance (time), acceleration distance, wakefield structure, and nonlinear space charge forces, and it also shows how ultralow emittance beams can be produced using ionization injection methods.

Confocal microphotoluminescence mapping of coupled and detuned states in photonic molecules

We study the coupling of cavities defined by the local modulation of the waveguide width using confocal photoluminescence microscopy. We are able to spatially map the profile of the antisymmetric (antibonding) and symmetric (bonding) modes of a pair of strongly coupled cavities (photonic molecule) and follow the coupled cavity system from the strong coupling to the weak coupling regime in the presence of structural disorder. The effect of disorder on this photonic molecule is also investigated numerically with a finite-difference time-domain method and a semi-analytical approach, which enables us to quantify the light localization observed in either cavity as a function of detuning.

Generating high-brightness electron beams via ionization injection by transverse colliding lasers in a plasma-wakefield accelerator

The production of ultrabright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. The relatively low intensity lasers are polarized along the wake axis and overlap with the wake for a very short time. The result is that the residual momentum of the ionized electrons in the transverse plane of the wake is reduced, and the injection is localized along the propagation axis of the wake. This minimizes both the initial thermal emittance and the emittance growth due to transverse phase mixing. Simulations show that ultrashort (~8 fs) high-current (0.4 kA) electron bunches with a normalized emittance of 8.5 and 6 nm in the two planes, respectively, and a brightness of 1.7×10(19) A rad(-2) m(-2) can be obtained for realistic parameters.

Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at T(c1) = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm(-1), we observed probable signatures of successive magnetic transitions near T(c1) = 18 K and T(c2) = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at T(c1) = 18 K although a long-range order is formed.

Different inter-annual responses to availability and form of nitrogen explain species coexistence in an alpine meadow community after release from grazing

Plant species and functional groups in nitrogen (N) limited communities may coexist through strong eco-physiological niche differentiation, leading to idiosyncratic responses to multiple nutrition and disturbance regimes. Very little is known about how such responses depend on the availability of N in different chemical forms. Here we hypothesize that idiosyncratic year-to-year responses of plant functional groups to availability and form of nitrogen explain species coexistence in an alpine meadow community after release from grazing. We conducted a 6 year N addition experiment in an alpine meadow on the Tibetan Plateau released from grazing by livestock. The experimental design featured three N forms (ammonium, nitrate, and ammonium nitrate), crossed with three levels of N supply rates (0.375, 1.500 and 7.500 g N m^-2  yr^-1 ), with unfertilized treatments without and with light grazing as controls. All treatments showed increasing productivity and decreasing species richness after cessation of grazing and these responses were stronger at higher N rates. Although N forms did not affect aboveground biomass at community level, different functional groups did show different responses to N chemical form and supply rate and these responses varied from year to year. In support of our hypothesis, these idiosyncratic responses seemed to enable a substantial diversity and biomass of sedges, forbs, and legumes to still coexist with the increasingly productive grasses in the absence of grazing, at least at low and intermediate N availability regimes. This study provides direct field-based evidence in support of the hypothesis that idiosyncratic and annually varying responses to both N quantity and quality may be a key driver of community structure and species coexistence. This finding has important implications for the diversity and functioning of other ecosystems with spatial and temporal variation in available N quantity and quality as related to changing atmospheric N deposition, land-use, and climate-induced soil warming.

Recombinant glycerol dehydratase from Klebsiella pneumoniae XJPD-Li: induction optimization, purification and characterization

Glycerol dehydratase (GDHt) is the rate limiting enzyme in the biosynthesis of 1,3-propanediol from glycerol. The optimization of inducting process for recombinant GDHt from Klebsiella pneumoniae XJPD-Li carried out to increase specific activity and ratio of soluble form. The optimum condition was inducing under the isopropyl-beta-D-thiogalactoside concentration of 0.8 mM and the temperature of 20 degrees C for 3 h. Homogeneity of GDHt then was obtained by affinity chromatography, resulted in 2.11-fold purification and an overall yield of 47.5%. The optimum pH and reaction temperature of GDHt were pH 8.0 and 45 degrees C, respectively. The K(m) for glycerol, 1,2-propanediol, 1,2-ethanediol and coenzyme B12 were 0.48, 1.43, 3.07 mM, and 10.03 nM, respectively. The GDHt showed relatively stable even under temperature of 40 degrees C and a bit blunt to oxygen. The thermo-inactivation kinetic models were fit linear under different temperatures.

Changes in the bacterial communities of vacuum-packaged pork during chilled storage analyzed by PCR-DGGE

In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial communities of vacuum-packaged pork during chilled storage. Eight kinds of lactic acid bacteria (LAB) were identified from the strains isolated from MRS plates by PCR-DGGE of the V3 region, and Lactobacillus sakei was the representative isolate at the end of the monitoring. By means of the direct meat analysis of PCR-DGGE, LAB increased gradually and Carnobacterium sp./Car. divergens, Lactobacillus sakei and Lactococcus sp./Lc. piscium, became the predominant bacteria at the end of the storage. The results of Lactobacillus-specific PCR and DGGE showed that different Lactobacillus populations were present at different storage periods and Lb. sakei became the predominant bacteria in the end. In conclusion, the PCR-DGGE technique as a culture-independent method is applicable to monitoring bacterial population dynamics in vacuum-packaged pork.