The Evolution of Chirality in a Multiphoton Pair Production Process

Recent years, multiphoton pair production has become one of the most promising approach to investigate Schwinger effect. However, the production and evolution of chirality, a key topic in the study of this effect, has not been thoroughly considered in the context of multiphoton pair production. In this work, as the first step of filling this gap, we used the Dirac-Heisenberg-Wigner formalism to study the production and evolution of chirality in vacuum under the excitation of the spatially homogeneous electric and magnetic fields $\mathbf{E}(t)$ and $\mathbf{B}(t)$ that satisfy $\mathbf{E}(t)\parallel\mathbf{B}(t)$ and are only nonzero in a short time span $0<t<\tau$, which serve as a simplified model of the laser beams in multiphoton pair production experiments. Based on analytical calculation, we discovered that after the external fields vanish, an oscillation of pseudo-scalar condensate occurs in the system, which leads to the suppression of the chirality of the produced fermion pairs; at the same time, it introduces a special fermion energy $\epsilon_p=\sqrt{3} m$ at which the chiral charge distribution of the fermions maximizes. This novel phenomenon could help us identify different types of product in future multiphoton pair production experiments.Comment: 11 pages, 3 figure

Implications of the helicity conservation for on-shell and off-shell chirality production

We analyze the helicity conservation following from the axial Ward identity for the massless fermion. We discuss the pair production of a fermion, $\ell$, and an anti-fermion, $\bar{\ell}$, from the annihilation process of photons, $\gamma$'s and conclude that the chirality production is prohibited in any annihilation process of on-shell $\gamma$'s. We demonstrate this selection rule in the tree-level process of $\gamma+\gamma\to \ell+\bar{\ell}$. We next consider the off-shell effect on the chirality production in the presence of the background magnetic field. We point out that the particle conversion process under the magnetic field induces the polarization of an incident $\gamma$, which can also be interpreted intuitively from the helicity conservation.Comment: 9 pages, 4 figure

Drilling Engineering Design of Well WT-1

Well WT-1 is a key exploratory well deployed at Jiangjin district of Chongqing for the exploration of shale gas reservoir with the design depth of 4,900.00 m and designed drilled strata at Ordovician Pagoda formation. Due to the complex situations in this area, there are some technical problems, for example, prediction accuracy of formation pressure is poor, Maokou formation is gas bearing formation with ultra-high pressure, and coal seam and shale bed are easy to collapse. Therefore, the well designing comprehensively adopted conventional casing program design methods, setting position design methods and safety risk assessment technique for casing program design; metal ion polymer drilling fluid system was designed in the upper part, and aluminum amine blocking anti-sloughing drilling fluid system was applied in the lower interval of interest. For well cementing design, conventional cement slurry system was used in the upper part and non-permeable latex channeling preventable slurry system was used in the lower part to improve the quality of cement-formation interface, and two special filter cake curing agents were also used in the design

1,1′-(2,5-Dimethyl­thio­phene-3,4-di­yl)diethanone

The title compound, C10H12O2S, crystallizes with four mol­ecules in the asymmetric unit. The main conformational difference between these mol­ecules is the orientation of the acetyl groups with respect to the ring. Whereas one acetyl group is only slightly twisted with respect to the thio­phene ring [C—C—C—O torsion angles = 165.7 (4), −164.6 (4), 164.3 (4) and −163.6 (4)°], the other acetyl group is markly twisted out of the ring plane [C—C—C—O torsion angles = −61.2 (6), 61.3 (7), −59.7 (7) and 59.9 (6)°]. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions into infinite chains along the c axis

A New Insight into the Role of CART in Cocaine Reward: Involvement of CaMKII and Inhibitory G-Protein Coupled Receptor Signaling

Cocaine- and amphetamine-regulated transcript (CART) peptides are neuropeptides that are expressed in brain regions associated with reward, such as the nucleus accumbens (NAc), and play a role in cocaine reward. Injection of CART into the NAc can inhibit the behavioral effects of cocaine, and injecting CART into the ventral tegmental area (VTA) reduces cocaine-seeking behavior. However, the exact mechanism of these effects is not clear. Recent research has demonstrated that Ca2+/calmodulin-dependent protein kinase II (CaMKII) and inhibitory G-protein coupled receptor (GPCR) signaling are involved in the mechanism of the effect of CART on cocaine reward. Hence, we review the role of CaMKII and inhibitory GPCR signaling in the effect of CART on cocaine reward and provide a new insight into the mechanism of that effect. In this article, we will first review the biological function of CART and discuss the role of CART in cocaine reward. Then, we will focus on the role of CaMKII and inhibitory GPCR signaling in cocaine reward. Furthermore, we will discuss how CaMKII and inhibitory GPCR signaling are involved in the mechanistic action of CART in cocaine reward. Finally, we will provide our opinions regarding the future directions of research on the role of CaMKII and inhibitory GPCR signaling in the effect of CART on cocaine reward

Identification and characterization of a ribose 2′-O-methyltransferase encoded by the ronivirus branch of Nidovirales.

Peer reviewe

Histone demethylase IBM1-mediated meiocyte gene expression ensures meiotic chromosome synapsis and recombination

Histone methylation and demethylation play important roles in plant growth and development, but the involvement of histone demethylation during meiosis is poorly understood. Here we show that disruption of Arabidopsis thaliana INCREASE IN BONSAI METHYLATION 1 (IBM1) causes incomplete synapsis, chromosome entanglement and reduction of recombination during meiosis, leading to sterility. Interestingly, these ibm1 meiotic defects are rescued by mutations in either SUVH4/KYP or CMT3. Using transcriptomic analyses we show that mutation of IBM1 down-regulates thousands of genes expressed in meiocytes, and that expression of about 38% of these genes are restored to wild type levels in ibm1 cmt3 double mutants. Changes in the expression of 437 of these, including the ARABIDOPSIS MEI2-LIKE AML3-5 genes, are correlated with a significant reduction of gene body CHG methylation. Consistently, the aml3 aml4 aml5 triple have defects in synapsis and chromosome entanglement similar to ibm1. Genetic analysis shows that aml3 aml4 aml5 ibm1 quadruple mutants resembles the ibm1 single mutant. Strikingly, over expression of AML5 in ibm1 can partially rescue the ibm1 meiotic defects. Taken together, our results demonstrate that histone demethylase IBM1 is required for meiosis likely via coordinated regulation of meiocyte gene expression during meiosis

Molecular Design Strategy to Construct the Near-Infrared Fluorescent Probe for Selectively Sensing Human Cytochrome P450 2J2

Cytochrome P450 2J2 (CYP2J2), a key enzyme responsible for oxidative metabolism of various xenobiotics and endogenous compounds, participates in a diverse array of physiological and pathological processes in humans. Its biological role in tumorigenesis and cancer diagnosis remains poorly understood, owing to the lack of molecular tools suitable for real-time monitoring CYP2J2 in complex biological systems. Using molecular design principles, we were able to modify the distance between the catalytic unit and metabolic recognition moiety, allowing us to develop a CYP2J2 selective fluorescent probe using a near-infrared fluorophore (E)-2-(2-(6-hydroxy-2, 3-dihydro-1H-xanthen-4-yl)­vinyl)-3,3-dimethyl-1-propyl-3H-indol-1-ium iodide (HXPI). To improve the reactivity and isoform specificity, a self-immolative linker was introduced to the HXPI derivatives in order to better fit the narrow substrate channel of CYP2J2, the modification effectively shortened the spatial distance between the metabolic moiety (O-alkyl group) and catalytic center of CYP2J2. After screening a panel of O-alkylated HXPI derivatives, BnXPI displayed the best combination of specificity, sensitivity and applicability for detecting CYP2J2 in vitro and in vivo. Upon O-demethylation by CYP2J2, a self-immolative reaction occurred spontaneously via 1,6-elimination of p-hydroxybenzyl resulting in the release of HXPI. Allowing BnXPI to be successfully used to monitor CYP2J2 activity in real-time for various living systems including cells, tumor tissues, and tumor-bearing animals. In summary, our practical strategy could help the development of a highly specific and broadly applicable tool for monitoring CYP2J2, which offers great promise for exploring the biological functions of CYP2J2 in tumorigenesis