Search

Spectral hardness of gamma-ray bursts can be characterized by either hardness ratio or peak energy, and the inconsistency of these parameters can reflect spectral diversity and complexity. We have chosen 310 Swift bursts with well-measured X-ray afterglows to analyze the distributions of their peak energies and hardness ratios before and after absorption of neutral hydrogen. We categorize them into four types according to X-ray temporal patterns and calculate the hardness ratios of both γ -rays and X-rays. It is found that the hardness ratios of X-rays are systematically smaller than those of γ -rays. We also find that both γ -ray hardness ratios and peak energies of bursts of types I, II, and III are identically distributed and are significantly lower than the corresponding measurements of type IV bursts in statistics, which hints that the evolving spectra of type IV bursts are most probably affected by the geometry of outflows. This proves that the influence of neutral hydrogen absorption on the estimation of hardness ratio is negligible even though it can reduce the brightness of γ /X-rays somewhat. Furthermore, we verify that almost all the observed spectra of gamma-ray bursts can be described by a broken power-law function and confirm a magnetar origin for the bursts with internal X-ray plateaus.

The relation between the event rate of long gamma-ray bursts and the star formation rate is still controversial, especially at the low-redshift end. Dong et al. confirmed that the gamma-ray burst rate always exceeds the star formation rate at a low redshift of z < 1 in spite of the sample completeness. However, the reason for low-redshift excess is still unclear. Since low-luminosity bursts are at smaller redshifts generally, we choose three Swift long burst samples and classify them into low- and high-luminosity bursts in order to check whether the low-redshift excess is existent and if the excess is biased by the sample size and completeness. To degenerate the redshift evolution from luminosity, we adopt the nonparametric method to study the event rate of the two types of long bursts in each sample. It is found that the high-luminosity burst rate is consistent with the star formation rate within the whole redshift range, while the event rate of low-luminosity bursts exceeds the star formation rate at a low redshift of z < 1. Consequently, we conclude that the low-redshift excess is contributed by the low-luminosity bursts with possibly new origins unconnected with the star formation, which is also independent of the sample size and the sample completeness.

The objective of this study was to examine the effects of different abiotic stresses on the activity of an NADP-dependent malic enzyme (NADP-ME) and the corresponding gene transcription in the leaves of the hexaploid wheat (Triticum aestivum L.) The activity of the NADP-ME enzyme was increased by water stress (20 % polyethylene glycol 6000), low temperature (4 °C), darkness, salinity (200 mM NaCl), abscisic acid and salicylic acid. The transcription of the TaNADP-ME1 gene decreased in response to all of the stresses except darkness and NaCl. In addition, the transcription of TaNADP-ME2 was down-regulated by all of the tested treatments and could not be detected under dark stress.

TaCer6 was firstly cloned by rapid amplification of cDNA ends (RACE) and identified as a tissue-specific gene in wheat. To determine if environmental factors such as drought and low temperature induce TaCer6 transcription, we examined the effects of these factors on TaCer6 in two wheat cultivars. Our results demonstrated that light was essential for TaCer6 transcription, salt stress inhibited TaCer6 expression and application of salicylic acid enhanced TaCer6 transcripts accumulation. In addition, polyethylene glycol (PEG 6000) and abscisic acid increased the expression of TaCer6 more in the drought- and cold-tolerant cultivar Jinmai47 than in non-tolerant cultivar Shi4185. Low temperature increased TaCer6 transcription in Jinmai47 while decreased it in Shi4185.

Unfavourable environment brings many kinds of stresses to plants. To survive such stresses, efficient resistance is required for the plants. Multifunctional genes enable the cross-talk among the various abiotic stress resistance systems. This paper reviews the action mechanisms of multifunctional genes. These genes can be classified into three groups: genes encoding diverse proteins through mRNA splicing (e.g. AOX in rice); genes like BADH, P5CS and HAV that control drought, salinity, osmotic and heat stress resistance; and a gene family, for example AQP, controlling transport of many compounds including water and nutrients. These genes participate in signal sensing and transduction, transcriptional regulation and functional gene activation during stress resistance induction. Furthermore, it should be noted that, under abiotic stresses, the regulation cascades are mutually interdependent and there also exists a close correlation between those cascades and normal plant growth and development.

This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV’s up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

OBJECTIVE: Glioma is characterized by high metastasis with poor outcomes. Long non-coding RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) was well-explored in numerous human cancers, including glioma. This study aimed to provide a novel action mechanism of MALAT1 in glioma. MATERIALS AND METHODS: The expression of MALAT1, microRNA-384 (miR-384) and Golgi membrane protein 1 (GOLM1) was detected by quantitative Real-time polymerase chain reaction (qRT-PCR). The protein levels of GOLM1, light chain3 (LC3-II/LC3-I), p62, Vimentin and E-cadherin were proved by Western blot. Cell migration and invasion were monitored using the transwell assay. Bioinformatics tool star-Base was used to predict target genes and associated binding sites. RNA immunoprecipitation assay (RIP) and dual-luciferase reporter assay were utilized to verify the relationship between miR-384 and MALAT1 or GOLM1. Tumor formation analysis in nude mice was conducted to ascertain the role of MALAT1 in vivo. RESULTS: MALAT1 was highly expressed in glioma tissues and cells. MALAT1 knockdown inhibited autophagy, migration and invasion of glioma cells. MiR-384 was a target of MALAT1, and miR-384 inhibition reversed the effects of MALAT1 knockdown in glioma cells. GOLM1 was a target of miR-384, and miR-384 inhibition eliminated the function of GOLM1 downregulation in glioma cells. In addition, GOLM1 was regulated by MALAT1 through miR-384. Moreover, MALAT1 knockdown blocked tumor growth and development in vivo. CONCLUSIONS: MALAT1 knockdown depleted migration and invasion by inhibiting autophagy through MALAT1/miR-384/GOLM1 axis in glioma in vitro and in vivo. The MALAT1/miR-384/GOLM1 axis was first proposed in our report, enriching the action mechanism of MALAT1 in glioma. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Glioma is a primary intracranial tumor with an unfavorable prognosis. Evolving evidence indicates that circular RNA Tau tubulin kinase 2 (circ-TTBK2) is a cancer-associated gene. Therefore, this study was to explore the potential role of circ-TTBK2. MATERIALS AND METHODS: Levels of circ- TTBK2, microRNA (miR)-761, and integrin subunit beta 8 (ITGB8) were determined by adopting quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to detect cell viability, and the invaded cells were distinguished utilizing transwell assay. Iron and lipid reactive oxygen species (ROS) assays were implemented to examine the iron (total iron and ferrous iron) and lipid-based ROS in glioma cells, respectively. Besides, dual-luciferase reporter assay was administrated to illustrate the interaction between miR-761 and circ-TTBK2 or ITGB8. The role of circ-TTBK2 was identified via xenograft tumor model. RESULTS: Levels of circ-TTBK2 and ITGB8 were upregulated, whereas miR-761 level was low-expressed in glioma tissues and cells. Circ-TTBK2 was a sponge of miR-761 to modulate ITGB8. Additionally, circ-TTBK2 knockdown or miR-761 increase could retard cell proliferation, invasion, and promote ferroptosis in glioma cells. Interestingly, miR-761 inhibitor could abolish the repressive impact of circ-TTBK2 silencing on cell growth in vitro. Also, the influence of miR-761 mimic on cell phenotypes was regained after ITGB8 upregulation. Meanwhile, circ-TTBK2 deficiency caused the decrease of tumor growth. CONCLUSIONS: Circ-TTBK2 regulated cell proliferation, invasion and ferroptosis via targeting ITGB8 by sponging miR-761 in glioma, providing a promising biomarker for the clinical therapy of human glioma. [ABSTRACT FROM AUTHOR]

The morphological stability of NiSi1-uGeu ternary alloy films formed by reacting Ni with single-crystal (sc) and polycrystalline (poly) Si1-xGeu is studied (u can be different from x). The agglomeration of NiSi1-uGeu films on Si0.7Ge0.3 occurs at 550°C after rapid thermal processing for 30 s, independently of the crystallinity of the Si1-xGeu. This behavior distinctly different from NiSi: NiSi films on poly-Si display a poorer morphological stability and degrade at lower temperatures than NiSi on sc-Si. On strained Si1-xGex, the presence of Ge simultaneously gives rise to two effects of different origin: mechanical and thermodynamic. The main driving forces behind the agglomeration of NiSi1-uGeu on sc-Si1-xGex are found to be the stored strain energy in the Si1-xGex and the larger (absolute) free energy of formation of NiSi compared to NiGe. The latter constitutes the principal driving force behind the agglomeration of NiSi1-uGeu on poly-Si1-xGex and is not affected by the degree of crystallinity of Si1-xGex. The total free-energy change also includes terms corresponding to the entropy of mixing of Si and Ge in both Si1-xGex and NiSi1-uGeu. Calculations show that the strain energy and the total free-energy change can be 5–7 times (with 30 at.% Ge) the surface/interface and grain-boundary energies in a NiSi film or the grain-boundary energy in an underlying poly-Si. These latter energies are responsible for the agglomeration of NiSi on sc- and poly-Si. The agglomeration takes place primarily via the interdiffusion of Si and Ge between Si1-xGex and NiSi1-uGeu. A structure likely to improve the stability of NiSi1-uGeu/Si1-xGex is discussed. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate the expression of apoptosis-related genes and their correlation with prognosis in cervical cancer patients. MATERIALS AND METHODS: The expressions of Survivin, Fas and FasL in tissues of cervical cancer, cervical intraepithelial neoplasia (CIN), chronic cervicitis and normal cervix wer detected by immunohistochemical staining, and the relationship between the expression of Survivin, Fas and FasL and clinical pathologic characteristics of cervical cancer was correlation analysis. RESULTS: The positive expression rates of Survivin and FasL in cervical cancer tissues were significantly higher than those in tissues of normal cervix, chronic cervicitis and CIN (p < 0.05), but lower positive expression rate of Fas was observed in cervical cancer tissues when compared with that in normal cervix, chronic cervicitis and CIN tissues (p < 0.05). The expression of Survivin was significantly correlated with clinical staging and lymph node metastases of cervical cancer (p < 0.05). The expression of FasL was correlated with lymph node metastases, clinical staging and pathological grading of cervical cancer (p < 0.05). The expression of Survivin was negatively correlated with that of Fas (r = -0.517, p < 0.01), but positively correlated with that of FasL (r = 0.381, p < 0.01) in tissues of cervical cancer. CONCLUSIONS: The up-regulated expression of Survivin and FasL and down-regulated expression of Fas may be involved in the carcinogenesis and development of cervical cancer. The expression of FasL may be one of the prediction indexes for disease progression and prognosis in cervical cancer. [ABSTRACT FROM AUTHOR]

Spectrum-energy correlations of peak energy with total prompt γ-ray emission energies, namely , , and , had been studied for long gamma-ray bursts (GRBs) previously by many authors. These energy correlations were proposed to measure the universe and classify GRBs as useful probes. However, most of these relations were built by non-Swift bursts. The spectrum-energy correlations of short bursts have not been systematically established yet; in particular, how the newly found GRB170817A matches these energy relations is unknown to date. We will first refresh the three spectrum-energy relations of Swift/BAT and Fermi/GBM long bursts and build the corresponding relations of short bursts. Then, we confirm whether they are commonly available as a discriminator of short and long GRBs. Some potential violators to these relations will be investigated. Combining with the plane of peak energy versus fluence, we select 31 short and 252 long GRBs with well-measured peak energy and redshift to study the issue of GRB classifications connected with the above energy relations statistically. We find that the three energy relations do exist in our new GRB samples and they are marginally consistent with some previous results. We report for the first time that short GRBs hold the three corresponding energy relations having the consistent power-law indices with long GRBs. It is found that these energy relations can be adopted to discriminate GRBs successfully if they are put in the peak energy versus fluence plane. Excitingly, we point out that GRB090510 matches the energy relations of and , but violates the relation. More excitingly, we find that GRB170817A is an outlier to all the three energy correlations. [ABSTRACT FROM AUTHOR]

The morphological stability of NiSi1-uGeu ternary alloy films formed by reacting Ni with single-crystal (sc) and polycrystalline (poly) Si1-xGeu is studied (u can be different from x). The agglomeration of NiSi1-uGeu films on Si0.7Ge0.3 occurs at 550°C after rapid thermal processing for 30 s, independently of the crystallinity of the Si1-xGeu. This behavior distinctly different from NiSi: NiSi films on poly-Si display a poorer morphological stability and degrade at lower temperatures than NiSi on sc-Si. On strained Si1-xGex, the presence of Ge simultaneously gives rise to two effects of different origin: mechanical and thermodynamic. The main driving forces behind the agglomeration of NiSi1-uGeu on sc-Si1-xGex are found to be the stored strain energy in the Si1-xGex and the larger (absolute) free energy of formation of NiSi compared to NiGe. The latter constitutes the principal driving force behind the agglomeration of NiSi1-uGeu on poly-Si1-xGex and is not affected by the degree of crystallinity of Si1-xGex. The total free-energy change also includes terms corresponding to the entropy of mixing of Si and Ge in both Si1-xGex and NiSi1-uGeu. Calculations show that the strain energy and the total free-energy change can be 5–7 times (with 30 at.% Ge) the surface/interface and grain-boundary energies in a NiSi film or the grain-boundary energy in an underlying poly-Si. These latter energies are responsible for the agglomeration of NiSi on sc- and poly-Si. The agglomeration takes place primarily via the interdiffusion of Si and Ge between Si1-xGex and NiSi1-uGeu. A structure likely to improve the stability of NiSi1-uGeu/Si1-xGex is discussed. [ABSTRACT FROM AUTHOR]

Goos-Hänchen (GH) shift, an interference phenomenon describing the lateral shift of the reflected beam along the interface during total internal reflection, has attracted great interests in the field of quantum transport in two-dimensional materials. In particular, the GH effect generates a novel pseudospin-dependent scattering effect in graphene, which in turn results in an $8e^{2}/h$ conductance step in the bipolar junctions. Here, we reveal that a barrier region with effective barrier strength χ can greatly enrich the GH effect in graphene junctions. In contrast to the conventional case where the negative shift is allowed only in the p - n junction, the thin barrier enables both negative and positive spatial shifts in p I n and n I n junctions, where I represents the barrier region. More interestingly, the lowest channel degeneracy can be efficiently varied by tuning χ in both the symmetric p I n I p and the asymmetric pn I p junctions, leading to a highly controllable switch that switches the conductance between $8e^{2}/h$ and $4e^{2}/h$ . These results advance the knowledge of GH effects in electronic materials and suggest experimental avenues for its observation and manipulation.