bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monte Carlo simulation of UV-driven synthesis of complex organic molecules on icy grain surfaces
Authors: Ochiai Y. , Ida S. , Shoji D. 
Published: May 2024

Context. Complex organic molecules (COMs) have been widely observed in molecular clouds and protostellar environments. One of the formation mechanisms of COMs is radical reactions on the icy grain surface driven by UV irradiation. While many experiments have reported that various COMs (including biomolecules) can be synthesized under such ice conditions, the majority of the reaction processes are unclear. Complementary numerical simulations are necessary to unveil the synthetic process behind the formation of COMs.
Aims. In this study, we develop a chemical reaction simulation using a Monte Carlo method. To explore the complex reaction network of COM synthesis, the model was designed to eliminate the need to prepare reaction pathways in advance and to keep computational costs low. This allows for broad parameter surveys and a global investigation of COM synthesis reactions. With this simulation, we investigate the chemical reactions occurring on icy dust surfaces during and after UV irradiation, assuming a protoplanetary disk environment. We aim to reveal the types of organic molecules produced in a disk and the formation mechanisms of COMs, in particular, amino acids and sugars.
Methods. The Monte Carlo method we developed here produces reaction sequences by selecting a reaction from all candidate reactions at each calculation step, based on Arrhenius-type weighting. For our purpose, we significantly accelerated the calculation by adopting an approximate estimation of activation energy without expensive quantum chemical calculations.
Results. The results show that photodissociation and subsequent radical-radical reactions cause random rearrangement of the covalent bonds in the initial molecules composed of methanol, formaldehyde, ammonia, and water. Consequently, highly complex molecules such as amino acids and sugars were produced in a wide range of the initial conditions. We found that the final abundances of amino acids and sugars have extremely similar dependence on the atomic ratios of the initial molecules, which peak at C/H ~ 0.1–0.3 and O/H ~ 0.3–0.5, although the amino acids abundance is usually more than ten times higher than that of sugars. To understand this dependence, a semi-analytical formula was derived. Additionally, parameter surveys of temperature, photon energy, and other factors have suggested that the decomposition reactions of amino acids and sugars undergo a rapid transition within the threshold of a given parameter.
Touching Surfaces: einfache Anwendung, große Auswirkung
Authors: Krämer Carolin L. , Siems Katharina , Müller Daniel W. , Leuko Stefan , Mücklich Frank , Maurer Matthias , Moeller Ralf 
Published: May 2024

ZUSAMMENFASSUNGMikroorganismen begleiten uns in unserem Alltag als essenzieller Teil des menschlichen Körpers und der von uns bewohnten Lebensräume. Während viele der Mikroorganismen für uns Menschen nützlich sind, können einige von ihnen Infektionen verursachen. Die einzigartigen Bedingungen, die während Raumfahrtmissionen vorliegen, wirken sich auch auf das Immunsystem aus, wodurch opportunistische Pathogene eine Gefahr darstellen können. Viele Mikroorganismen können lange auf Oberflächen überleben, die dadurch zu einer Quelle der Verbreitung von opportunistisch pathogenen Mikroorganismen werden. Um diese Verbreitung zu verhindern, können antimikrobielle Oberflächen eingesetzt werden. Touching Surfaces ist ein interdisziplinäres Projekt, das antibakterielle Oberflächen für die Anwendung in Raumfahrt und auf der Erde testet. Die einfache Implementierung aufgrund der geringen Größe und Tragbarkeit der Touch Arrays ermöglicht die Prüfung antimikrobieller Oberflächen unter verschiedenen Bedingungen.
Influence of Pregnancy Intention on Postpartum Contraceptive Choice at an Urban Academic Medical Center
Authors: St John Meghan , Sullivan Kirby , DeFranco Emily A. , Kelly Elizabeth 
Published: May 2024

Objective This study aimed to describe postpartum contraception preferences in the context of pregnancy intention (PI).
Study Design A prospective cohort study analyzing postpartum contraceptive choice (PCC) in 431 postpartum women who delivered at a single academic medical center. PCC in women with an unintended or mistimed pregnancy was compared to contraceptive choice in women with an intended pregnancy using the adapted National Survey of Family Growth categorization. Mistimed and unintended pregnancies were grouped for analysis. Generalized linear modeling estimated the relative influence of PI on PCC adjusting for maternal age, race, and parity.
Results Nearly three out of four (71.9%) pregnancies were mistimed or unintended. These pregnancies were more likely in women who were non-Hispanic Black (62.3%), unmarried (86.3%), 18 to 24 years (51.3%), and insured by Medicaid or Medicare (82.1%), compared to women with an intended pregnancy, p-value <0.001. Women with mistimed or unintended pregnancy were 83% more likely to choose highly effective, user-independent methods compared to any other or no method, adjusted relative risk (aRR) = 1.83 (95% confidence interval [CI]: 1.36, 2.47), and more likely to desire voluntary sterilization, aRR = 2.70 (95% CI: 1.58, 4.59). Additionally, women with these pregnancies were 56% more likely to use user-independent methods compared to user-dependent methods, aRR = 1.56 (95% CI: 1.18, 2.06).
Conclusion Women with mistimed or unintended pregnancies are 83% more likely to choose highly effective postpartum contraception or voluntary sterilization, and thus initiatives are necessary to increase access and affordability to these methods before hospital discharge after delivery.
Key Points
Asymmetric Access to Chiral Sulfinyl Compounds as Bioisosteres of Carbonyl Compounds
Authors: Liu Gang , Wu Jie , Wang Chenxin , Wu Xinyu , Huang Jiapian 
Published: May 2024

AbstractThe sulfinyl group, as one of the bioisosteres of carbonyl groups, attracts considerable attention in the field of synthetic chemistry. In particular, the asymmetric construction of chiral sulfinyl compounds and their derivatives remains in the early stages of development. Sulfinyl compounds mainly include sulfoxides, sulfinate esters and sulfinamides, according to the different functional groups connected to the sulfur atom. This Review summarizes the fascinating recent progress made over the past decade on the asymmetric synthesis of enantiopure sulfinyl derivatives.1	Introduction2	Asymmetric Synthesis of Chiral Sulfoxides3	Asymmetric Synthesis of Chiral Sulfinate Esters4	Asymmetric Synthesis of Chiral Sulfinamides5	Conclusion and Outlook
Benzothiazole-Directed Enantioselective Borylation of Secondary Benzylic C–H Bonds Using Iridium Catalysis
Authors: Chen Lili , Xu Senmiao , Xie Liang-Jun 
Published: May 2024

AbstractReported here is the iridium-catalyzed regio- and enantio­selective secondary benzylic C–H borylation using benzothiazole as the directing group. Various monosubstituted 2-arylalkylbenzo[d]thiazole were well-tolerated, affording the corresponding products in moderate to good yields with good enantioselectivity. The C–B bond in one boryl­ated product could undergo stereospecific transformations to form a series of C–C and C–heteroatom bonds.
Polymicrogyria, Cobblestone Malformations, and Tubulin Mutation (Overmigration beyond Pial Limiting Membrane): Diagnosis, Treatment, and Rehabilitation Approach
Authors: Lo Bianco Manuela , Fichera Valeria , Zanghì Antonio , Praticò Andrea D. , Falsaperla Raffaele , Vecchio Michele , Marino Francesco , Palmucci Stefano , Belfiore Giuseppe , Foti Pietro , Polizzi Agata 
Published: May 2024

AbstractPolymicrogyria, cobblestone malformations, and tubulinopathies constitute a group of neuronal migration abnormalities beyond the pial limiting membrane. Their etiopathogenesis remains unclear, with proposed environmental and genetic factors, including copy number variations and single-gene disorders, recently categorized.Polymicrogyria features numerous small circumvolutions separated by large, shallow grooves, often affecting the perisylvian cortex with various presentations. Clinical manifestations vary depending on lesion degree, extent, and location, commonly including epilepsy, encephalopathies, spastic tetraparesis, mental retardation, and cortical function deficits.Cobblestone malformations exhibit a Roman-like pavement cortex, affecting both hemispheres symmetrically due to disruption of the glia limitans, frequently linked to glycosyltransferase gene mutations. Classified separately from lissencephaly type II, they are associated with congenital muscular dystrophy syndromes such as Fukuyama congenital muscular dystrophy, Walker–Warburg syndrome, and muscle–eye–brain disease.Tubulinopathies encompass diverse cerebral malformations resulting from α-tubulin isotype gene variants, exhibiting a wide clinical spectrum including motor/cognitive impairment, facial diplegia, strabismus, and epilepsy.Diagnosis relies on magnetic resonance imaging (MRI) with age-specific protocols, highlighting the gray–white junction as a polymicrogyria marker, though neonatal diagnosis may be challenging due to technical and brain maturity issues.To date, no effective treatments are available and management include physiotherapy, speech and language therapy, and vision training program for oculomotor disabilities; antiepileptic drugs are commonly necessary, and most severe forms usually require specific nutritional support.
Spectrum of Resistance Mechanisms to ALK TKIs in NSCLC: Largest Single-Center Experience from India
Authors: Batra Ullas , Nathany Shrinidhi , Sharma Mansi , P. Amrith B. , Vaidya Shriya , Mattoo Sakshi , Kumar Dushyant , Mehta Anurag 
Published: May 2024

Abstract
Introduction Anaplastic lymphoma kinase (ALK) rearranged non-small cell lung carcinoma (NSCLC) has emerged as a distinct entity with growing number of potent ALK tyrosine kinase inhibitors (TKIs). Despite showing durable responses and promising survival rates, resistance to these ensue. This is the largest series of repeat biopsies from patients of ALK-positive NSCLC progressing on ALK-directed therapy from this part of the world. Using a combinatorial approach of genomics and histology, we describe the spectrum of various resistance mechanisms encountered.
Methods This is a cross-sectional study recruiting ALK-positive NSCLC cases who have progressed on any line ALK TKI and have undergone repeated biopsies followed by genomic sequencing by next-generation sequencing (NGS).
Results Thirty-two ALK-positive NSCLC patients progressed on TKI were enrolled. Median age was 53 years (range: 36–75 years) with a male predilection (male:female 1.3:1). Twenty-seven (84.4%) cases harbored an additional resistance mechanism. Eighteen of these harbored an on-target ALK alteration, with L1196M gatekeeper mutation being the most common, in 11 cases, and G1202 alteration in 3 cases. In 9 cases an off-target alteration was detected, the most frequent being TP53 mutation in 8 cases, KRAS mutation in 4 cases and MET amplification in 3 cases. Four patients underwent sequential NGS testing and allele frequency changes in ALK fusion and resistance mechanisms were demonstrated. Sixteen patients have been offered lorlatinib therapy, the median progression-free survival of which has not yet been reached.
Conclusion This is the largest series depicting ALK resistance mechanisms from a single center to date. The SPACEWALK study which demonstrated ALK TKI resistance mechanisms using plasma-based genotyping was a multicentric study. The spectrum encountered in this study is distinct from the rest of the world, thus highlighting heterogeneity within ALK-rearranged tumors. Comprehensive clinical evaluation at disease progression coupled with NGS-based genotyping will pave the way for lucid understanding of disease biology, thus aiding in the institution of optimal therapy.
2 Cross-Dehydrogenative Coupling: Development and Perspectives
Authors: Huang C.-Y. , Kang H. , Li C.-J. 
Published: May 2024

AbstractCross-coupling transformations are a fundamental and expeditious tool for building up molecular complexity. Among the possible strategies, cross-dehydrogenative coupling (CDC) has received great attention in the past two decades, not only for its high step- and atom-economy, but also for the diverse feedstock availability. This article discusses the advantages of CDC, the practical applications, and some perspectives of this rising field in order to provide readers with an introduction to this flourishing area in organic synthesis.
5 (Het)Arene/(Het)Arene Cross-Dehydrogenative Coupling for C(sp2)—C(sp2) Bond Formation
Authors: Jha N. , Kapur M. 
Published: May 2024

AbstractAmong the various strategies for C—C bond formation, cross-dehydrogenative coupling (CDC) reactions form an integral class, primarily due to their step- and atom-economic nature. With dihydrogen as the only side-product, this method couples two unmodified C—H bonds, thereby avoiding the need for prefunctionalization of substrates. This chapter focuses exclusively on transition-metal-catalyzed C(sp2)—C(sp2) bond-forming CDC reactions between arenes/hetarenes. The most viable methods, leading to the facile syntheses of biaryl scaffolds, have been assembled, thereby providing a platform for easy access to a wide variety of arene or hetarene skeletons.
9 (Het)Arene/Alkane Cross-Dehydrogenative Coupling for C(sp2)—C(sp3) Bond Formation
Authors: Iwasaki T. , Kambe N. 
Published: May 2024

AbstractIntroduction of alkyl groups onto arenes and hetarenes is a fundamental modification of (het)arenes and can exert significant effects on their physical, chemical, and/or biological properties. Among alkylation reactions, the cross-dehydrogenative coupling of (het)arenes with hydrocarbons through double C—H bond cleavage is a straightforward synthetic method that avoids prefunctionalization of the substrate(s). This review provides an overview of the alkylation of (het)arenes, including arenes, perfluoroarenes, and nitrogen, oxygen, and sulfur heterocycles, by hydrocarbons via cross-dehydrogenative coupling.
13 C—C Bond Formation in Flow Systems Through Cross-Dehydrogenative Coupling
Authors: Martins G. M. , Silva R. C. , Zimmer G. C. , Brocksom T. J. , de Oliveira K. T. 
Published: May 2024

AbstractThe development of new reaction pathways seeking to improve synthetic efficiency is a continuing necessity. In this context, the formation of C—C bonds through cross-dehydrogenative coupling has emerged as a powerful and elegant strategy in organic synthesis and, together with continuous-flow technology, new perspectives have engaged the interest of the scientific community. Continuous-flow chemistry provides new synthetic possibilities, solving problems that are common with reactions performed under batch conditions, such as long reaction times, difficulty of scale-up, reproducibility, general efficiency, and safety, among others. In this chapter, C—C bond formation in flow systems through cross-dehydrogenative coupling is described.
15 C—C Bond Formation through Cross-Dehydrogenative Coupling in Natural Product and API Synthesis
Authors: Fukuta T. , Kanai M. 
Published: May 2024

AbstractThis review describes cross-dehydrogenative coupling (CDC) reactions used for the synthesis of natural products and active pharmaceutical ingredients (APIs). CDC reactions generally streamline the synthesis of multifunctional molecules because they do not require preactivation or prefunctionalization of the substrates. C(sp2)—C(sp2), C(sp2)—C(sp3), and C(sp3)—C(sp3) bond-forming CDC reactions through Fujiwara–Moritani reaction, Friedel–Crafts-type reactions, Minisci-type reactions, and enolate coupling reactions are summarized.
17 C—O Bond Formation through Cross-Dehydrogenative Coupling
Authors: Miyabe H. 
Published: May 2024

AbstractDehydrogenative C—H/O—H coupling has emerged as an atom-economical strategy. This review highlights representative reactions and selected recent examples of dehydrogenative C—O bond formation. Dehydrogenative oxygenations of C(sp3)—H bonds of alkanes and C(sp2)—H bonds of arenes, alkenes, aldehydes, or imines are summarized.
11 Cross-Dehydrogenative Coupling for C(sp3)—C(sp3) Bond Formation
Authors: Li X. , Song Q. 
Published: May 2024

AbstractCross-dehydrogenative coupling (CDC) is regarded as the most straightforward approach to forge a C(sp3)—C(sp3) bond. In this process, two C(sp3)—H bonds are transformed into a C(sp3)—C(sp3) bond, either with or without a sacrificial oxidant, or under a photo- or electrocatalytic system. Several reaction modes, including both non-enantioselective and enantioselective, have been developed for the preparation of a series of structurally different organic compounds. In this review, the most useful reaction systems for cross-dehydrogenative coupling between C(sp3)—H bonds, including enantioselective versions, are presented.
12 Electrochemical C—C Bond Formation through Cross-Dehydrogenative Coupling
Authors: Arun V. , Saha S. K. , De Sarkar S. 
Published: May 2024

AbstractCross-dehydrogenative coupling is a challenging strategy that continues to evolve, as it avoids the typical requirements of prefunctionalization of substrates for C—C coupling transformations. Electrooxidation can be applied in dehydrogenative processes as a replacement for redox reagents, thereby making the protocol greener and more sustainable. In this review, recent developments in electrochemical dehydrogenative couplings for the construction of C—C bonds are summarized. There is a particular focus on the functionalization of C(sp2) and C(sp3) positions to access heterocyclic scaffolds, conjugated systems, and annulated frameworks.
14 C—C Bond Formation in Water through Cross-Dehydrogenative Coupling
Authors: Adak L. , Ghosh T. , Ranu B. C. 
Published: May 2024

AbstractThe development of efficient procedures for useful reactions continues to be of great importance in organic synthesis. In the past decades, cross-dehydrogenative coupling (CDC) has been extensively investigated as one of the most efficient and sustainable synthetic approaches for the construction of C—C (or C—X) bonds. Cross-dehydrogenative coupling can be applied to produce new C—C or C—X bonds (X = N, O, S, P) under oxidative conditions, without prefunctionalization of reactants, by efficient and simple routes. Conventionally, these reactions have generally been performed in dry organic solvents as it is thought that water molecules may react with the reaction intermediates and catalytic species, hindering catalytic processes. However, in recent years, water has been successfully used as an alternative reaction medium for efficient cross-dehydrogenative coupling reactions. The obvious advantages of using water are its abundance, non-flammability, non-toxicity, and environmental friendliness. This review highlights recent progress in the formation of C—C bonds through cross-dehydrogenative coupling in water.
16 C—N Bond Formation through Cross-Dehydrogenative Coupling
Authors: Chowdhury D. , Koner M. , Baidya M. 
Published: May 2024

AbstractAmines are versatile building blocks in organic chemistry, with widespread occurrence in natural products, agrochemicals, and functional materials. Traditional methods for the synthesis of amines have been largely replaced by cross-dehydrogenative C—N bond formation processes, which formally generate hydrogen as the byproduct and obviate the need for prefunctionalized substrates. Consequently, such reactions are extremely attractive from a viewpoint of green chemistry and sustainability. This chapter deals with cross-dehydrogenative C—N bond formation reactions via strategies based on transition-metal-catalyzed directed C—H activation and visible-light-mediated coupling.
Product-specific reaction kinetics in continuous uniform supersonic flows probed by chirped-pulse microwave spectroscopy
Authors: Guillaume Théo , Hays Brian M. , Gupta Divita , Cooke Ilsa R. , Abdelkader Khedaoui Omar , Hearne Thomas S. , Drissi Myriam , Sims Ian R. 
Published: May 2024

Experimental studies of the products of elementary gas-phase chemical reactions occurring at low temperatures (&lt;50 K) are very scarce, but of importance for fundamental studies of reaction dynamics, comparisons with high-level quantum dynamical calculations, and, in particular, for providing data for the modeling of cold astrophysical environments, such as dense interstellar clouds, the atmospheres of the outer planets, and cometary comae. This study describes the construction and testing of a new apparatus designed to measure product branching fractions of elementary bimolecular gas-phase reactions at low temperatures. It combines chirped-pulse Fourier transform millimeter wave spectroscopy with continuous uniform supersonic flows and high repetition rate laser photolysis. After a comprehensive description of the apparatus, the experimental procedures and data processing protocols used for signal recovery, the capabilities of the instrument are explored by the study of the photodissociation of acrylonitrile and the detection of two of its photoproducts, HC3N and HCN. A description is then given of a study of the reactions of the CN radical with C2H2 at 30 K, detecting the HC3N product, and with C2H6 at 10 K, detecting the HCN product. A calibration of these two products is finally attempted using the photodissociation of acrylonitrile as a reference process. The limitations and possible improvements in the instrument are discussed in conclusion.
Virtual photon exchange vs electron transfer in interparticle Coulombic electron capture
Authors: Graves Vincent , Šenk Jan , Kolorenč Přemysl , Sisourat Nicolas , Gorfinkiel Jimena D. 
Published: May 2024

We have investigated Interparticle Coulombic Electron Capture (ICEC) using an ab initio approach for two systems, H+ + H2O and H + H2O+. In this work, we have determined the contribution of virtual photon exchange and electron transfer to the total ICEC cross section as a function of the distance between the charged and neutral particles. Furthermore, we have shown that the relative orientation of the electron acceptor and neighbor systems affects the magnitude of the ICEC cross sections by at least two orders at relatively small distances. This geometry dependence, present even for distances as large as 10 a0, is due to the electron transfer contribution. The relative magnitude of each contribution to ICEC seems to depend on the system studied. By replacing the projectile electron with a positron, we have confirmed that electron transfer also takes place in positron collisions and that the charge of the projectile has a noticeable effect on the process, particularly at low scattering energies.