The Circumstance-Driven Bivariate Integer-Valued Autoregressive Model.

The novel circumstance-driven bivariate integer-valued autoregressive (CuBINAR) model for non-stationary count time series is proposed. The non-stationarity of the bivariate count process is defined by a joint categorical sequence, which expresses the current state of the process. Additional cross-dependence can be generated via cross-dependent innovations. The model can also be equipped with a marginal bivariate Poisson distribution to make it suitable for low-count time series. Important stochastic properties of the new model are derived. The Yule-Walker and conditional maximum likelihood method are adopted to estimate the unknown parameters. The consistency of these estimators is established, and their finite-sample performance is investigated by a simulation study. The scope and application of the model are illustrated by a real-world data example on sales counts, where a soap product in different stores with a common circumstance factor is investigated.

A New Overdispersed Integer-Valued Moving Average Model with Dependent Counting Series.

A new integer-valued moving average model is introduced. The assumption of independent counting series in the model is relaxed to allow dependence between them, leading to the overdispersion in the model. Statistical properties were established for this new integer-valued moving average model with dependent counting series. The Yule-Walker method was applied to estimate the model parameters. The estimator's performance was evaluated using simulations, and the overdispersion test of the INMA(1) process was applied to examine the dependence between counting series.

Theoretical scheme for simultaneously observing forward-backward photoelectron holography.

Photoelectron angular momentum distribution of He+ driven by a few-cycle laser is investigated numerically. We simultaneously observe two dominant interference patterns with one shot of lasers by solving the 3D time-dependent Schrodinger equation. Analysis of a semiclassical model identifies these two interference patterns as two types of photoelectron holography. The interference pattern with Pz>0 is a type of forward rescattering holography, which comes from the interference between direct (reference) and rescattered (signal) forward electrons ionized in the same quarter-cycle. The interference pattern with Pz<0 is a type of backward rescattering holography, which comes from the interference between a direct electron ionized in the third quarter-cycle and rescattered backward electron ionized in the first quarter-cycle. Moreover, we propose a method to distinguish this backward rescattering holography and intracycle interference patterns of direct electrons.

Synthesis of 1,3-Disubstituted Imidazo[1,5-a]pyridines from Amino Acids via Catalytic Decarboxylative Intramolecular Cyclization.

A copper/iodine cocatalyzed decarboxylative cyclization of α-amino acids is described. Starting from the readily available amino acids and either 2-benzoylpyridines or 2-benzoylquinolines, 1,3-disubstituted imidazo[1,5-a]pyridines and 1,3-disubstituted imidazo[1,5-a]quinolines were prepared in excellent yields.

Reexamining the high-order harmonic generation of HD molecule in non-Born-Oppenheimer approximation.

The high-order harmonic generation of the HD molecule is studied in non-Born-Oppenheimer approximation. It is found that there are only the odd harmonics in the harmonic spectrum of the HD molecule though the generation of even harmonics is possible in principle. Theoretical analysis [T. Kreibich et al., Phys. Rev. Lett. 87, 103901 (2001)] reveals that the nuclear dipole moment can contribute to the generation of the even harmonics, but the acceleration of the nucleus is about three orders of magnitude less than that of the electron. Hence, the even harmonics cannot be observed in the harmonic spectrum of the HD molecule.

Overcoming the Coupling Dilemma in DNA-Programmable Nanoparticle Assemblies by "Ag+ Soldering".

Strong coupling between nanoparticles is critical for facilitating charge and energy transfers. Despite the great success of DNA-programmable nanoparticle assemblies, the very weak interparticle coupling represents a key barrier to various applications. Here, an extremely simple, fast, and highly efficient process combining DNA-programming and molecular/ionic bonding is developed to address this challenge, which exhibits a seamless fusion with DNA nanotechnology.

Copper-catalyzed oxidative amination of sp(3) C-H bonds under air: synthesis of 1,3-diarylated imidazo[1,5-a]pyridines.

A copper(II)-catalyzed tandem reaction between pyridine ketone and benzylamine was developed by using clean O2 as an oxidant. This transformation proceeded via an efficient condensation-amination-oxidative dehydrogenation process, affording 1,3-diarylated imidazo[1,5-a]pyridines in excellent yields.

Tailor-made Au@Ag core-shell nanoparticle 2D arrays on protein-coated graphene oxide with assembly enhanced antibacterial activity.

Water-dispersible two-dimensional (2D) assemblies of Au@Ag core-shell nanoparticles are obtained through a highly selective electroless silver deposition on pre-assembled gold nanoparticles on bovine serum albumin (BSA)-coated graphene oxide (BSA-GO). While neither BSA-GO nor AuNP-decorated BSA-GO shows any antibacterial ability, the silver-coated GO@Au nanosheets (namely GO@Au@Ag) exhibit an enhanced antibacterial activity against Gram-negative Escherichia coli (E. coli) bacteria, superior to unassembled Au@Ag nanoparticles and even ionic Ag. Such an improvement may be attributed to the increased local concentration of silver nanoparticles around a bacterium and a polyvalent interaction with the bacterial surface. In addition, the colloidal stability of this novel nano-antimicrobial against the formation of random nanoparticle aggregates guarantees a minimized activity loss of the Au@Ag nanoparticles. The antibacterial efficacy of GO@Au@Ag is less sensitive to the existence of Cl⁻, in comparison with silver ions, providing another advantage for wound dressing applications. Our research unambiguously reveals a strong and very specific interaction between the GO@Au@Ag nanoassembly and E. coli, which could be an important clue toward a rational design, synthesis and assembly of innovative and highly active antibacterial nanomaterials.

Direct alkylation of quinoxalinones with electron-deficient alkenes enabled by a sequential paired electrolysis.

The metal-free alkylation of N-heterocycles with alkenes has remained a synthetic challenge. We report here the successful implementation of metal-free alkylation of quinoxalinones with electron-deficient alkenes enabled by a sequential paired electrolysis. This protocol provides a mechanistically distinct approach to prepare a variety of C-3 alkylated quinoxalinones that are otherwise quite difficult to synthesize by other means.

Radiation characteristics analysis for spallation products of lead-bismuth target and tungsten-iron-nickel target.

The radiation characteristics of spallation products are important references for evaluating the materials used as spallation targets. Therefore, it is necessary to study the radiation characteristics of spallation products. In this study, the spallation products of tungsten-iron-nickel target and lead-bismuth target were calculated and analyzed based on the radionuclide distributions and decay photon shielding of the spallation products. The radionuclide distributions of the spallation products were calculated using FLUKA, and the shielding of decay photons was calculated with OpenMC. In addition, the variance reduction function with an importance card was added to the OpenMC code to allow its use for calculating deep penetration problems.

Metal-Free Synthesis of N-Heterocycles via Intramolecular Electrochemical C-H Aminations.

N-heterocycles are key structural units in many drugs, biologically interesting molecules and functional materials. To avoid the residues of metal catalysts, the construction of N-heterocycles under metal-free conditions has attracted much research attention in academia and industry. Among them, the intramolecular electrochemical C-H aminations arguably constitute environmentally friendly methodologies for the metal-free construction of N-heterocycles, mainly due to the direct use of clean electricity as the redox agents. With the recent renaissance of organic electrosynthesis, the intramolecular electrochemical C-H aminations have undergone much progress in recent years. In this article, we would like to summarize the advances in this research field since 2019. The emphasis is placed on the reaction design and mechanistic insight. The challenges and future developments in the intramolecular electrochemical C-H aminations are also discussed.

Collagen I Induces Preeclampsia-Like Symptoms by Suppressing Proliferation and Invasion of Trophoblasts.

Preeclampsia is a common obstetric disorder affecting 2-8% of pregnancy worldwide. Fibrosis is an important histological change occurring in preeclamptic placenta, and might depend on the excess deposition of collagen I. However, the role of fibrotic placenta and collagen I in the pathogenesis of preeclampsia remains unclear. Therefore, we analyzed the collagen deposition and the expression of Collagen I in human placenta by Masson staining, Sirius red staining and western blotting. Further, the role of collagen I in preeclampsia pathogenesis was studied in C57BL/6 mice. HTR-8/SVneo cells were used to investigate the mechanisms underlying the effects of collagen I in trophoblasts by transcriptome sequencing and pharmacological agonists. Human preeclamptic placenta exhibited a significantly higher degree of fibrosis in stem villi and terminal villi than normal placenta, and was characterized by collagen I deposition. In vivo, a single injection of collagen I on gestational day 0.5 led to an increase in systolic pressure of pregnant mice from gestational days 4.5-17.5, to a decrease in weight and number of embryos, and to enhanced placental collagen I expression and degree of fibrosis compared with control mice. In vitro, collagen I attenuated the proliferation and invasion of HTR-8SV/neo cells. This effect could be reversed by treatment with agonists of ERK and ß-catenin. Moreover, transcriptome sequencing demonstrated that signaling pathways related to cell proliferation and invasion were significantly downregulated in HTR-8SV/neo cells. Thus, we propose that collagen I induced preeclampsia-like symptoms by suppressing the proliferation and invasion of trophoblasts through inhibition of the ERK phosphorylation and WNT/ß-catenin signaling pathways. Our findings could pave the way to the discovery of small-molecule inhibitors for preeclampsia treatment and future studies with larger sample size are required.

ANKDD1A may serve as a critical gene in the immune microenvironment of breast cancer.

BACKGROUND: Breast cancer (BC), a very heterogeneous systemic disease, is the most frequently seen malignancy in women, especially in some developed countries or regions. Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki67 have been extensively used to predict the clinical outcome, but it is still a hotspot to search for more predictive prognostic markers. Ankyrin repeat and death domain containing 1A (ANKDD1A), which contains nine ankyrin repeats, has been discovered to play a role of tumor suppressor in glioblastoma multiforme (GBM). However, its role in BC remains unknown so far. METHODS: ANKDD1A expression and clinical information of BC were extracted from the TCGA dataset. Then, the ANKDD1A expression level was explored in BC from different perspectives, including clinical stage, molecular subtype, histology type and immune microenvironment. Afterwards, functional enrichment analysis of ANKDD1A co-expressed genes was carried out to estimate the role of ANKDD1A in BC, and the methylation status of ANKDD1A was evaluated by MEXPRESS. In addition, the correlation of ANKDD1A with immunocytes was explored, and survival analysis was carried out to evaluate the prognostic value of ANKDD1A in BC. RESULTS: ANKDD1A decreased in BC compared with the para-cancerous tissues. Additionally, ANKDD1A was up-regulated in early-stage BC, ER negative group, infiltrating lobular carcinoma, and the normal subtype in BC molecular subtypes. According to functional enrichment analysis, ANKDD1A co-expressed genes were mainly involved in the immune process. Also, our results revealed that ANKDD1A was tightly associated with T cells. Survival analysis suggested that, patients with higher ANKDD1A expression had more favorable prognosis than those with lower ANKDD1A expression. CONCLUSIONS: ANKDD1A may serve as a critical gene in the pathogenesis of BC and the immune microenvironment of BC tissues.

KO t Bu-promoted oxidative dimerizations of 2-methylquinolines to 2-alkenyl bisquinolines with molecular oxygen.

KO t Bu-promoted oxidative dimerizations of 2-methylquinolines with molecular oxygen as the oxidant have been developed for the first time. The mild reaction conditions allow the homo- and cross-dimerizations of 2-methylquinolines to give functionalized 2-alkenyl bisquinolines in highly trans-selective manners.

Organic Photoredox-Catalyzed Synthesis of δ-Fluoromethylated Alcohols and Amines via 1,5-Hydrogen-Transfer Radical Relay.

The hydrotrifluoromethylation of benzyl-protected homoallylic alcohol and amine derivatives catalyzed by 2,4,5,6-tetra(9 H-carbazol-9-yl)isophthalonitrile (4CzIPN) was developed. This reaction delivered δ-fluoromethylated free alcohols and amines with in situ deprotection of benzyl protecting group under mild irradiation conditions. 4CzIPN was found to be a competent metal-free photoredox catalyst for activating several types of fluoromethylation reagents including CF3SO2Cl, Togni's reagent, and 2-bromo-2,2-difluoroacetate via oxidative quenching and also CF3SO2Na through reductive quenching to allow direct hydrotrifluoromethylation of simple alkenes and Michael acceptors.

Electrochemical Synthesis of trans-2,3-Disubstituted Aziridines via Oxidative Dehydrogenative Intramolecular C(sp3)-H Amination.

An electrochemical oxidative dehydrogenative C(sp3)-H amination reaction to construct trans-2,3-disubstituted aziridines is reported, which avoids using external oxidants and generates only hydrogen gas as the byproduct. With KI as the mediator and electrolyte, the desired aziridines were prepared in good yields in an undivided cell at room temperature. The potential value of this mild electrochemical strategy was further highlighted by the gram-scale synthesis.

Electrosynthesis of Trisubstituted 2-Oxazolines via Dehydrogenative Cyclization of ß-Amino Arylketones.

An electrochemically intramolecular functionalization of C(sp3)-H bonds with masked oxygen nucleophiles was developed. With KI as the catalyst and electrolyte, diverse trisubstituted 2-oxazolines were constructed in good to excellent yields. This newly developed electrochemical dehydrogenative approach features external oxidant-free and additive-free conditions.

Scalable Electrochemical Dehydrogenative Lactonization of C(sp2/sp3)-H Bonds.

A practical, electrochemical method is developed for the direct dehydrogenative lactonization of C(sp2/sp3)-H bonds under external oxidant- and metal-free conditions, delivering diverse lactones, including coumarin derivatives with excellent regioselectivity. The scalable nature of this newly developed electrochemical process was demonstrated on a 40 g scale following an operationally simple protocol. The remote lactonization of C(sp3)-H bonds would constitute an important synthetic advance toward electrochemical C-O bond formation.

Cobalt-Catalyzed Monoselective Ortho-C-H Functionalization of Carboxamides with Organoaluminum Reagent.

A simple triphenylphosphine-ligated cobalt catalyst is reported for the direct ortho-C-H methylation and ethylation of aromatic, heteroaromatic, alkenyl, and even aliphatic carboxamides with inexpensive organoaluminum reagents in the presence of a cheap alkyl chloride as oxidant. This reaction shows monoselectivity in contrast with previously established C-H methylation methodologies.

KOtBu-Promoted Oxidation of (Hetero)benzylic Csp3-H to Ketones with Molecular Oxygen.

An efficient and practical (hetero)benzylic sp3 C-H oxidation method has been developed. Notably, this user-friendly protocol employs inexpensive potassium tert-butoxide (KOtBu) as a promoter and proceeds under mild conditions using oxygen as the oxidant. A large variety of oxidation products were prepared in good to excellent yields. The utility of this "green" methodology was further demonstrated by the scale-up preparation of a biologically valued molecule.