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The constitutive relationships of Al-Mg-Si alloy deformed at various strain rates, temperatures and strains were studied. The microstructure evolution was quantitatively characterized and analyzed, including recrystallization fraction, grain sizes, local misorientation, geometrically necessary dislocation and stored strain energy during hot deformation and subsequent heat treatment. The results show that the dislocation density and energy storage are linear with lnZ during hot deformation and subsequent heat treatment, indicating continuous recrystallization occurring in both processes. With higher lnZ, the dislocation density declines more sharply during subsequent heat treatment. When lnZ is less than 28, dislocation density becomes more stable with less reduction during subsequent heat treatment after hot deformation. As these dislocations distribute along low angle grain boundaries, the subgrain has good stability during subsequent heat treatment. The main recrystallization mechanism during hot deformation is continuous dynamic recrystallization, accompanied by geometric dynamic recrystallization at higher lnZ.

To realize accurate estimation of state of charge (SOC) and state of health (SOH), Li-ion battery’s operating characteristic is analyzed in this article while fully considering temperature, degree of aging, and other practical factors that could impact their operating status. On the basis of the nonlinear autoregressive with exogenous input (NARX) architecture, an improved dynamic recurrent neural network (DRNN) with the ability of dynamic mapping is established, which is more suitable than the static network for estimating the batteries’ state with strongly nonlinear and dynamic behaviors. Meanwhile, a self-adaptive weight particle swarm optimization (SWPSO) algorithm is introduced for training the network. Compared with the gradient descent algorithm, the SWPSO algorithm could improve the error convergence speed and avoid falling into local optimum. The validation results highlight that the presented method is able to improve the estimation accuracy of the SOC and SOH under different conditions including temperature, current, and degree of aging and has strong robustness and ability of generalization.

The sedimentary facies/microfacies, which can be correlated with well logs, determine reservoir quality and hydrocarbon productivity in carbonate rocks. The identification and evaluation of sedimentary facies/microfacies using well logs are very important in order to effectively guide the exploration and development of oil and gas. Previous carbonate facies/microfacies identification methods based on conventional well log data often exist multiple solutions. This paper presents a new method of facies/microfacies identification based on core–conventional logs–electrical image log–geological model, and the method is applied in the fourth member of the Dengying Formation (Deng 4) in the Gaoshiti-Moxi area of the Sichuan Basin. Firstly, core data are used to calibrate different types of facies/microfacies, with the aim to systematically clarify the conventional and electrical image log responses for each type of facies/microfacies. Secondly, through the pair wise correlation analysis of conventional logs, GR, RT and CNL, are selected as sensitive curves to establish the microfacies discrimination criteria separately. Thirdly, five well logging response models and identification charts of facies/microfacies are established based on electrical image log. The sedimentary microfacies of 60 exploratory wells was analyzed individually through this method, and the microfacies maps of 4 layers of the Deng 4 Member were compiled, and the plane distribution of microfacies in the Gaoshiti-Moxi area of the Sichuan Basin was depicted. The comparative analysis of oil testing or production results of wells reveals three most favorable types of microfacies and they include algal psammitic shoal, algal agglutinate mound, and algal stromatolite mound, which provide a reliable technical support to the exploration, development and well deployment in the study area.

The escalating prevalence of antibiotic-resistant bacteria has led to a serious global public health problem; therefore, there is an urgent need for the development of structurally innovative antibacterial agents. In our study, a series of biphenyl and dibenzofuran derivatives were designed and synthesized by Suzuki-coupling and demethylation reactions in moderate to excellent yields (51–94% yield). Eleven compounds exhibited potent antibacterial activities against the prevalent antibiotic-resistant Gram-positive and Gram-negative pathogens, among which compounds 4′-(trifluoromethyl)-[1,1′-biphenyl]-3,4,5-triol (6i) and 5-(9H-carbazol-2-yl) benzene-1,2,3-triol (6m) showed the most potent inhibitory activities against methicillin-resistant Staphylococcus aureus and multidrug-resistant Enterococcus faecalis with MIC (minimum inhibitory concentration) values as low as 3.13 and 6.25 μg/mL, respectively. Compounds 3′,5′-dimethyl-[1,1′-biphenyl]-3,4,4′,5-tetraol (6e), 4′-fluoro-[1,1′-biphenyl]-3,4,5-triol (6g), and 4′-(trifluoromethyl)-[1,1′-biphenyl]-3,4,5-triol (6i) showed comparable inhibitory activities with ciprofloxacin to Gram-negative bacterium carbapenems-resistant Acinetobacter baumannii. Study of the structure–activity relationship indicated that a strong electron-withdrawing group on the A ring and hydroxyl groups on the B ring of biphenyls were beneficial to their antibacterial activities, and for benzo-heterocycles, N-heterocycle exhibited optimal antibacterial activity. These results can provide novel structures of antibacterial drugs chemically different from currently known antibiotics and broaden prospects for the development of effective antibiotics against antibiotic-resistant bacteria.

Zinc–air batteries (ZABs) are among the most promising electrochemical energy storage devices which feature high energy density, decent rechargeability, low cost, and eco-friendliness. However, the...

Numerous long noncoding RNAs (lncRNAs) are abnormally expressed in breast cancer (BC), but the underlying mechanisms remain large unknown. Here, we aimed to investigate the functions and mechanisms of lncRNA cancer susceptibility candidate 9 (CASC9) in BC. Western blotting and quantitative real-time PCR (qRT-PCR) were performed to assess gene and protein expression, respectively. The proliferative and metastatic abilities of BC cells were tested by cell counting kit-8 and transwell assays, respectively. The formation of lymphatic vessels was detected by tube formation assay. Chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays were performed to verify molecular interactions. CASC9 was found to be highly expressed in BC tissues and cell lines, and ectopic overexpression was positively associated with tumor volume, TNM stage, and lymph node metastasis. In addition, CASC9 silencing significantly inhibited the proliferation and invasion of BC cells, as well as BC-associated invasion and formation of lymphatic vessels of human dermal lymphatic endothelial cells. Mechanical studies demonstrated that CASC9 could be transcriptionally activated by STAT3 and elevate SOX4 expression by enhancing the acetylation of its promoter region. Our results illustrated that STAT3-activated CASC9 served as a tumor-promoting gene involved in promoting BC invasion and BC-associated formation of lymphatic vessels by upregulating SOX4 through altering H3K27ac level. This finding elucidated a new underlying network of CASC9 in the metastasis of BC.

With the potential to circumvent the need for scarce and cost-prohibitive platinum-based catalysts in proton-exchange membrane fuel cells, anion-exchange membrane fuel cells (AEMFCs) are emerging as alternative technologies with zero carbon emission. Numerous noble metal-free catalysts have been developed with excellent catalytic performance for cathodic oxygen reduction reaction in AEMFCs. However, the anodic catalysts for hydrogen oxidation reaction (HOR) still rely on noble metal materials. Since the kinetics of HOR in alkaline media is 2-3 orders of magnitude lower than that in acidic media, it is a major challenge to either improve the performance of noble metal catalysts or to develop high-performance noble metal-free catalysts. Additionally, the mechanisms of alkaline HOR are not yet clear and still under debate, further hampering the design of electrocatalysts. Against this backdrop, this review starts with the prevailing theories for alkaline HOR on the basis of diverse activity descriptors

Escape of cancer cells from chemotherapy is a problem in the management of cancer patients. Research on chemotherapy resistance has mainly focused on the heterogeneity of cancer cells, multiple gene mutations, and quiescence of malignant cancer cells. However, some studies have indicated that interactions between cancer cells and vascular cells promote resistance to chemotherapy. Here, we established mouse leukemia models using the cell lines THP‐1 or MEG‐1. These were derived from acute and chronic myeloid leukemias, respectively, and highly expressed DNA replication factor PSF1, a member of the GINS complex. We found that, after anti‐cancer drug administration, surviving GFP‐positive leukemia cells in the bone marrow were located adjacent to blood vessels, as previously reported in a subcutaneous solid tumor transplantation model. Treating THP‐1 and MEG‐1 cells with anti‐cancer drugs in vitro revealed that those most strongly expressing PSF1 were most chemoresistant, suggesting that PSF1 induces not only cell cycle progression but also facilitates cell survival. Indeed, when PSF1 expression was suppressed by shRNA, the growth rate was reduced and cell death was enhanced in both cell lines. Furthermore, PSF1 knockdown in leukemia cells led to a change in their location at a distance from the blood vessels in a bone marrow transplantation model. These findings potentially reflect a mechanism of escape of leukemic cells from chemotherapy and suggest that PSF1 may be a possible therapeutic target to enhance the effect of chemotherapy., Chemotherapy (AraC) in a leukemia cell transplantation model. We found that cancer cells strongly expressing PSF1 and localising near vascular areas were drug‐resistant. These findings suggest that the vascular niche might play a critical role in chemotherapy resistance. PSF1 might act as a potential therapeutic target to enhance the effect of chemotherapy and prognosis.

Motivated by quantum statistical mechanics, we propose an accurate analytical solution to the problem of Bose–Einstein condensation (BEC) of ideal bosons in a two-dimensional anisotropic harmonic trap. The study reveals that the number of noncondensed bosons is characterized by an analytical function, which relates to a series expansion of q-digamma functions in mathematics. The q-digamma function is a function of temperature, boson number, and anisotropic parameter. The analytical solution describes fully the experimental results of the BEC of ideal bosons in a two-dimensional anisotropic harmonic trap. We derive the analytical expressions of the critical temperature and the condensate fraction in the thermodynamic limit. The first main conclusion is that for a fixed temperature and boson number, there is a critical anisotropic parameter, which is the precise onset of BEC in this harmonically trapped two-dimensional system. The second main conclusion is that the critical temperature in a two-dimensional anisotropic harmonic trap is larger than that in a two-dimensional isotropic harmonic trap.

Objective Patients with opioid use disorder (OUD) have impaired attention, inhibition control, and memory function. The aldehyde dehydrogenase 2(ALDH2) gene has been associated with OUD and ALDH2 gene polymorphisms may affect aldehyde metabolism and cognitive function in other substance use disorder. Therefore, we aimed to investigate whether ALDH2 genotypes have significant effects on neuropsychological functions in OUD patients undergoing methadone maintenance therapy (MMT). Methods OUD patients undergoing MMT were investigated and followed-up for 12 weeks. ALDH2 gene polymorphisms were genotyped. Connors' Continuous Performance Test (CPT) and the Wechsler Memory Scale-Revised (WMS-R) were administered at baseline and after 12 weeks of MMT. Multivariate linear regressions and generalized estimating equations (GEEs) were used to examine the correlation between the ALDH2 genotypes and performance on the CPTs and WMS-R. Results We enrolled 86 patients at baseline; 61 patients completed the end-of-study assessments. The GEE analysis showed that, after the 12 weeks of MMT, OUD patients with the ALDH2 *1/*2＋*2/*2 (ALDH2 inactive) genotypes had significantly higher commission error T-scores (p= 0.03), significantly lower hit reaction time T-scores (p= 0.04), and significantly lower WMS-R visual memory index scores (p= 0.03) than did patients with the ALDH2 1*/*1 (ALDH2 active) genotype. Conclusion OUD patients with the ALDH2 inactive genotypes performed worse in cognitive domains of attention, impulse control, and memory than did those with the ALDH2 active genotype. We conclude that the ALDH2 gene is important in OUD and is associated with neuropsychological performance after MMT.

This study involves the crosstalk caused by the high-frequency parasitic parameters in the driver circuits of SiC MOSFETs, which are high-speed switching devices. A lumped parameter model for the high-frequency crosstalk of a driver circuit was established. Then, the relationships between the parameters and crosstalk of the driver circuit were analyzed. Finally, an improved SiC MOSFET driver circuit was proposed. The optimized driver circuit parameters can reduce the driver signal oscillation and minimize the crosstalk of the driver circuit. Verification was performed on a test platform of a full-bridge LLC converter. Test results show that the improved driver circuit can remarkably suppress crosstalk, increase the turn-off speed of SiC MOSFETs and reduce the switching loss. This demonstrates the effectiveness of the driver circuit.

Primordial black holes of planetary masses captured by compact stars are widely studied to constrain their composition fraction of dark matter. Such a capture may lead to an inspiral process and be detected through gravitational wave signals. In this Letter, we study the post-capture inspiral process by considering two different kinds of compact stars, i.e., strange stars and neutron stars. The dynamical equations are numerically solved and the gravitational wave emission is calculated. It is found that the Advanced LIGO can detect the inspiraling of a $10^{-5}$ solar mass primordial black hole at a distance of 10 kpc, while a Jovian-mass case can even be detected at megaparsecs. Promisingly, the next generation gravitational wave detectors can detect the cases of $10^{-5}$ solar mass primordial black holes up to ${\sim}1$ Mpc, and can detect Jovian-mass cases at several hundred megaparsecs. Moreover, the kilohertz gravitational wave signal shows significant differences for strange stars and neutron stars, potentially making it a novel probe to the dense matter equation of state., 15 pages, 7 figures, accepted by ApJL

In this paper, a large gain variable range, high linearity, low noise, low DC offset VGAs with a simple gain-dB variable circuit are introduced. In the VGAs chain, the last and the first VGAs employ Bipolar transistors, to improve the linearity and noise characteristics. And the middle three stages VGAs employ MOS transistors. The whole circuitry is designed in 0.35um BiCMOS process, including variable gain amplifiers (VGAs) , fixed gain amplifiers , gain control and DC offset cancellation parts. The automatic gain control loop (AGC) provides a process independent gain variable range of 60dB (including 50dB gain-dB-linearity variable range), with a 200us loop lock time, the VGAs provide a 73dB largest gain, the THD is less than 1% at a 1V(P-P) output level; the equivalent output integral noise is 0.011v/√hz@20MHz bandwidth. The whole area is 1173um*494 um, and the power is 7.1mA at 3.3V signal supply voltage.

Exact magnetic properties of two-dimensional (2D) spin-1 Cooper pairs are investigated within the framework of quantum statistical mechanics. We derive an exact analytical expression of the magnetization of 2D spin-1 Cooper pairs, which involves a q-digamma function and a q-Pochhammer symbol in mathematics. The magnetization density m(T) is a function of temperature T, Landé factor g, number density σ, and magnetic field B. Firstly, we examine the evolution of the magnetization density m(T) with the Landé factor g. m(T) is negative when g g c . Here, g c = 1 is the critical value of the Landé factor g, at which m ( T ) = 0 . Secondly, we examine the evolution of the magnetization density m(T) with the temperature T. When g m(T). The low-temperature asymptotic line is m ( T ) = − 387.5 nC s−1 and the high-temperature asymptotic line is m ( T ) = 0 . Finally, we examine the evolution of the magnetization density m(T) with the number density σ. No matter how large the Landé factor g is, there is a lower cutoff σ c of the number density σ. The lower cutoff number density is about σ c = 10 12 cm−2. If σ < σ c , the Cooper pair system does not support a solution of the reduced chemical potential x. As the number density σ is increased, the Bose–Einstein condensation of 2D Cooper pairs is strengthened.

Bose–Einstein condensation of two-dimensional spin-1 Cooper pairs in a uniform magnetic field is investigated within the framework of quantum statistical mechanics. We derive an exact analytical solution of two-dimensional spin-1 Cooper pairs in a uniform magnetic field, which involves a q-digamma function in mathematics. In two dimensions, it is found that the critical temperature and condensate fraction are monotonically increasing functions of magnetic field B, Landé factor g, and number density σ. Our investigation in two dimensions provides an example of the magnetic-field-tuned insulator-superconductor quantum phase transition.

Host genes critical for viral infection are effective antiviral drug targets with tremendous potential due to their universal characteristics against different subtypes of viruses and minimization of drug resistance. Accordingly, we execute a genome-wide CRISPR-Cas9 screen with multiple rounds of survival selection. Enriched in this screen are several genes critical for host sialic acid biosynthesis and transportation, including the cytohesin 2 (CYTH2), tetratricopeptide repeat protein 24 (TTC24), and N-acetylneuraminate synthase (NANS), which we confirm are responsible for efficient influenza viral infection. Moreover, we reveal that CYTH2 is required for the early stage of influenza virus infection by mediating endosomal trafficking. Furthermore, CYTH2 antagonist SecinH3 blunts influenza virus infection in vivo. In summary, these data suggest that CYTH2 is an attractive target for developing host-directed antiviral drugs and therapeutics against influenza virus infection.

During wireless charging, the transmission distance of electric vehicles varies, resulting in different levels of electromagnetic field leakage. An improved active shielding technology, the double-coil dynamic shielding technology, is proposed in this paper for wireless power transfer (WPT) systems with different transmission distances. Modeling, simulation, and experiments are performed for the WPT system with a double-coil dynamic shielding scheme and compared with other cases. The results show that the proposed double-coil dynamic shielding scheme is able to shield approximately 70% of the electromagnetic field leakage for WPT systems at different transmission distances. In addition, it essentially causes no degradation in transmission efficiency (only 3.1%). The effectiveness and feasibility of the proposed scheme are verified.

Flash memory is featured with salient advantages over conventional hard disks for massive data storage and efficient on-board data processing. A flash translation layer (FTL) is a critical component for flash-based storage devices to handle particular technical constraints of flash. It is desirable to use flash memory for the storage of massive remote sensing images and support on-board remote sensing data processing applications, which typically require high I/O performance and hence call for advanced FTL design and implementations. In this paper, we introduce our efforts in developing a reinforcement learning driven page-level mapping and caching scheme (named Q-FTL) that is adaptive and responsive to ever-changing I/O streams of on-board remote sensing image processing operations. The adaptability and responsiveness are achieved by the separation of large and small I/O requests, an integrated weighting scheme to measure access costs of cached translation pages, and a reinforcement learning driven cache replacement algorithm. We demonstrate the efficiency of the proposed approach using actual I/O traces generated from on-board remote sensing image processing applications. Experimental results show that Q-FTL improves over several current state-of-the-art FTLs by a large margin and even achieves competitive performance close to an idealized pure page mapping FTL in some cases.

Ribosome biogenesis (RiBi) is an extremely energy intensive process that is critical for gene expression. It is thus highly regulated, including through the tightly coordinated expression of over 200 RiBi genes by positive and negative transcriptional regulators. We investigated RiBi regulation as cells initiated meiosis in budding yeast and noted early transcriptional activation of RiBi genes, followed by their apparent translational repression 1 hour (h) after stimulation to enter meiosis. Surprisingly, in the representative genes examined, measured translational repression depended on their promoters rather than mRNA regions. Further investigation revealed that the signature of this regulation in our data depended on pre-treating cells with the translation inhibitor, cycloheximide (CHX). This treatment, at 1 h in meiosis, but not earlier, rapidly resulted in accumulation of RiBi mRNAs that were not translated. This effect was also seen in with CHX pre-treatment of cells grown in media lacking amino acids. For NSR1, this effect depended on the –150 to –101 region of the promoter, as well as the RiBi transcriptional repressors Dot6 and Tod6. Condition-specific RiBi mRNA accumulation was also seen with translation inhibitors that are dissimilar from CHX, suggesting that this phenomenon might represent a feedback response to global translation inhibition.

Based on the first principles calculations, the feasibility of the photocatalytic hydrogen production from water splitting driven by N-doped β-Ga2O3 in the visible light is investigated. The formation energy and dynamics properties are used to examine the stability of the doped structures. The absolute positions of the band energy edges are obtained and compared to the redox potentials of the hydrogen production reaction. Moreover, we calculate the carrier lifetime and mobility for both electron and hole of all the considered structures. The optical absorption is also calculated for each structure. The results show that the 5.00 at.% N-doped β-Ga2O3 has the satisfactory band energy edges, obvious difference of mobilities between electron and hole, and significant enhancement of absorption in visible light range, indicating it is a promising photocatalytic material to catalyze hydrogen production from water splitting under the irradiation of the visible light.

Because of stochastic nature of weather conditions, the predictability of photovoltaic (PV) power generation is poor. Compared with the point prediction, the probabilistic prediction of PV power generation can provide more information about the underlying uncertainties, which is beneficial to the stability and safety of grid dispatching and power system. Based on random forest (RF), fuzzy C-means (FCM), sparse Gaussian process (SPGP), improved grey wolf optimizer (IMGWO) algorithm, a hybrid probabilistic estimation method, in this paper, is proposed to predict the probability of PV power generation for every hour in one day. RF algorithm is firstly used to reduce multidimensional input variables. And according to the weather patterns, FCM method is adopted to divide data and get the similar samples. Finally, a hybrid forecasting method combines SPGP and IMGWO is applied to forecast the test data. With the simulation and experimental results, the validity and reliability of the proposed model (IMGWOSP) is verified. The results show that the proposed model has improved both accuracy and practicability, so the stability and safety of grid dispatching and power system can be improved.

Capacity degradation monitoring of lithium batteries is necessary to ensure the reliability and safety of electric vehicles. However, capacity of cell is related to its complex internal physicochemical reactions and thermal effects and cannot be measured directly. A data-driven remaining capacity estimation approach for lithium-ion batteries based on charging health feature extraction is presented in this work. The proposed method utilizes rational analysis and principal component analysis to extract and optimize health features of charging stage which adapt to various working conditions of battery. The remaining capacity estimation is realized by relevance vector machine and validations of different working conditions are made with six battery data sets provided by NASA Prognostics Center of Excellence. The results show high efficiency and robustness of the proposed method.

The Lane-Emden conjecture says that the subcritical Lane-Emden system admits no positive solution. In this paper, we present a necessary and sufficient condition to the Lane-Emden conjecture. This condition is an energy-type a priori estimate. The necessity of the condition we found can be easily checked. However, a major difficulty lies in the sufficiency. The proof is quite involving, but the benefit is that it reduces the longstanding problem to obtaining the a priori estimate of energy type.

It is known that the supercritical Hardy-Littlewood-Sobolev (HLS) systems with an integer power of Laplacian admit classic solutions. In this paper, we prove that the supercritical HLS systems with fractional Laplacians \begin{document}$ (-Δ)^s $\end{document} , \begin{document}$ s∈(0,1) $\end{document} , also admit classic solutions.

Background: Microvascular tissue transfer is a common reconstructive procedure. We designed a bioelectrical impedance assessment (BIA) system for quantitative analysis of tissue status. This study attempts to verify it through the animal model. Methods: The flaps of the rat model were monitored by the BIA system. Results: The BIA variation of the free flap in the rat after the vascular compromise was recorded. The non-vascular ligation limbs of the same rat served as a control group. The bio-impedance in the experimental group was larger than the control group. The bio-impedances of both the thigh/feet flaps in the experimental group were increased over time. In the thigh, the difference in bio-impedance from the control group was first detected at 10 kHz at the 3rd and last at 1 kHz at the 6th h, after vascular compromise. The same finding was observed in the feet. Compared with the control group, the bio-impedance ratio (1 kHz/20 kHz) of the experimental group decreased with time, while their variation tendencies in the thigh and feet were similar. Conclusions: The flap may be monitored by the BIA for vascular status.

Two-dimensional hexagonal boron nitride (hBN) has attracted large attentions as platforms for realizations for integrated nanophotonics and collective effort has been focused on the spin defect centers. Here, the temperature dependence of the resonance spectrum in the range of 5-600 K is investigated. The zero-field splitting (ZFS) parameter D is found to decrease monotonicly with increasing temperature and can be described by Varshni empirical equation perfectly, while E almost does not change. We systematically study the differences among different hBN nanopowders and provide an evidence of edge effects on ODMR of VB- defects. Considering the proportional relation between D and reciprocal of lattice volume, the thermal expansion might be the dominant reason for energy-level shifts. We also demonstrate that the VB- defects still exist stably at least at 600 K. Moreover, we propose a scheme for detecting laser intensity using the VB- defects in hBN nanopowders, which is based on the obvious dependence of its D value on laser intensity. Our results are helpful to gain insight into the spin properties of VB- and for the realizations of miniaturized, integrated thermal sensor.

Regardless of their different types of progenitors and central engines, gamma-ray bursts (GRBs) were always assumed to be standalone systems after they formed. Little attention has been paid to the possibility that a stellar companion can still accompany a GRB itself. This paper investigates such a GRB-involved binary system and studies the effects of the stellar companion on the observed GRB emission when it is located inside the jet opening angle. Assuming a typical emission radius of $\sim10^{15}\,$cm, we show that the blockage by a companion star with a radius of $R_\mathrm{c}\sim67\,\mathrm{R_\odot}$ becomes non-negligible when it is located within a typical GRB jet opening angle (e.g., $\sim10$ degrees) and beyond the GRB emission site. In such a case, an on-axis observer will see a GRB with a similar temporal behavior but 25% dimmer. On the other hand, an off-axis observer outside the jet opening angle (hence missed the original GRB) can see a delayed "reflected" GRB, which is much fainter in brightness, much wider in the temporal profile and slightly softer in energy. Our study can naturally explain the origin of some low-luminosity GRBs. Moreover, we also point out that the companion star may be shocked if it is located inside the GRB emission site, which can give rise to an X-ray transient or a GRB followed by a delayed X-ray bump on top of X-ray afterglows., Comment: 11 pages, 6 figures, 1 table, accepted by ApJ