Direct Construction Research Articles

Iodine-promoted amide formation via oxidative cleavage of indoles: novel quinazoline-4(3H)-one and tryptanthrin syntheses.

A highly efficient method for the direct construction of amide bonds via a selective cleavage of C-H and C[double bond, length as m-dash]C bonds in indole structures using an iodine-promoted approach was developed. Mechanistic studies indicated the formation of superoxide radicals obtained from molecular oxygen activation as a key intermediate step, which provided a precursor for subsequent oxidative ring-opening and intermolecular cyclization. A broad range of quinazolin-4(3H)-ones and tryptanthrins were synthesized in moderate to good yields under mild and environmentally benign conditions.

Modular dehydrogenative cross-nucleophile coupling for direct construction of tetrasubstituted carbons

An FeCl3-catalyzed cross-dehydrogenative coupling reaction for the construction of various types of C–Y (Y = C, N, O, S) bonds with air as a green oxidant.

Three constructions of Golay complementary array sets

<p style='text-indent:20px;'>Recently, two-dimensional (2-D) arrays with good correlation have been used in MIMO systems. In this paper, we investigate new 2-D Golay complementary array sets (GCASs), whose 2-D aperiodic auto-correlation sums are zero for all 2-D nonzero shifts. Firstly, based on the 2-D generalized Boolean functions, we propose a direct construction of new GCASs. Secondly, using horizontal concatenation, we give two indirect constructions of GCASs. The proposed constructions can provide a lot of GCASs with flexible parameters.</p>

Direct construction of interconnected Si3N4 nanowire networks for enhancing the thermal conductivity and mechanical performance of flexible composite films

An innovative strategy for the direct construction of continuous thermally conductive networks composed of ultra-long Si3N4NWs is proposed.

Potassium xanthate-promoted reductive sulfuration reaction: from aldehydes to thiol, disulfide, and thioester derivatives.

Herein, we developed a synthetic strategy for the direct construction of C-S bonds to obtain biologically active sulfur-containing compounds and a methodology involving the reductive sulfuration of aldehydes or ketones to obtain diverse substituted thiol, disulfide, and thioester derivatives. EtOCS2K is demonstrated as a potential substitute for the Berzelius reagent or Lawesson's reagent for the construction of C-S bonds.

Event-Based Optical Flow via Transforming Into Motion-Dependent View.

Event cameras respond to temporal dynamics, helping to resolve ambiguities in spatio-temporal changes for optical flow estimation. However, the unique spatio-temporal event distribution challenges the feature extraction, and the direct construction of motion representation through the orthogonal view is less than ideal due to the entanglement of appearance and motion. This paper proposes to transform the orthogonal view into a motion-dependent one for enhancing event-based motion representation and presents a Motion View-based Network (MV-Net) for practical optical flow estimation. Specifically, this motion-dependent view transformation is achieved through the Event View Transformation Module, which captures the relationship between the steepest temporal changes and motion direction, incorporating these temporal cues into the view transformation process for feature gathering. This module includes two phases: extracting the temporal evolution clues by central difference operation in the extraction phase and capturing the motion pattern by evolution-guided deformable convolution in the perception phase. Besides, the MV-Net constructs an eccentric downsampling process to avoid response weakening from the sparsity of events in the downsampling stage. The whole network is trained end-to-end in a self-supervised manner, and the evaluations conducted on four challenging datasets reveal the superior performance of the proposed model compared to state-of-the-art (SOTA) methods.

Compositional Synthesis of Controllers via Co-Büchi Barrier Certificates

The success of barrier certificates to ensure the safety of control systems has led to their adoption in designing controllers to guarantee more general ω-regular automata specifications. Recent developments in co-Büchi barrier certificates propose the direct construction of the product of the system and the automaton, ensuring that the accepting states of the automaton are visited finitely often. Despite the benefits, challenges arise when finding these certificates for large-scale systems. To overcome such challenges, we introduce a compositional controller synthesis via co-Büchi barrier certificates. We decompose the large-scale system into an interconnection of smaller subsystems, construct local certificates for these subsystems, and utilize a dissipativity-type condition to guarantee the existence of a certificate for the large-scale system. We design controllers for the subsystems that, when concatenated, act as a formally correct controller for the large-scale system. Finally, we illustrate our approach with a numerical example.

Recent trends in the synthesis and applications of β-iodovinyl sulfones: a decade of progress.

Direct vicinal difunctionalization of π-systems has emerged as a powerful platform for constructing multiple bonds in a single synthetic operation using simple chemical feedstocks. Over the past decade, there has been exponential growth in the direct construction of successive C-S and C-I bonds using a wide variety of sulfonyl and iodide reactants through 1,2-iodosulfonylation of alkynes in a regio- and stereo-selective manner. In this review, we mainly focus on the recent developments in the preparation of β-iodovinyl sulfones and their practical applications in organic synthesis. The most promising photoredox and electrochemical transformations for synthesizing β-iodovinyl sulfones are also reviewed. The multifunctional β-iodovinyl sulfones have recently been burgeoning as versatile synthetic precursors due to the combination of vinyl iodide and vinyl sulfone moieties, essential building blocks for diverse synthetic manipulations. We hereby present the chemistry of β-iodovinyl sulfones, which can be classified into numerous sections based on the sulfonyl surrogates, and potential synthetic approaches are systematically outlined.

Directional constructions in Matukar Panau

Abstract The Oceanic language Matukar Panau has three equivalent morphosyntactic strategies for describing the direction of the event represented by a verb, with a system of ten directional morphemes that can appear in each construction. This variation is explored using a corpus from Matukar Panau and analysed quantitatively with Bayesian regression analyses to assess what factors influence the choice of directional construction. Variables pertaining to the lexical verb and the directional morphemes are found to be the most important factors affecting the variation in the directional system. Sociolinguistic factors are shown to play a less significant role. The findings have implications for the grammaticalization of directional elements, as well as the typology of directional constructions in Oceanic languages.

Controllable Synthesis of N-Heterocycles via Hydride Transfer Strategy-Enabled Formal [5 + 1] and [5 + 2] Cyclizations.

The Brønsted acid-controlled switchable synthesis of indoline-fused tetrahydroquinolines and indole-fused benzazepines was developed through hydride transfer-enabled formal [5 + 1] and [5 + 2] cyclization reactions from indoles and N-alkyl o-aminobenzoketones. Indoline, furanone, and tetrahydroquinoline hybridized pentacyclic products were unprecedentedly accessed via a cascade condensation/hydride transfer/dearomatization-cyclization/deethylation/nucleophilic addition process. In addition, the undeveloped hydride transfer-involved [5 + 2] cyclizations were also realized for direct construction of indole-fused benzazepines.

Direct Z-scheme construction of C2N/Mg(OH)2 heterojunction and first-principles investigation of photocatalytic water splitting

Efficient water-splitting photocatalysts are pivotal in enhancing solar energy utilization to its maximum potential. Using first-principles calculations, the current study systematically explores the heterojunction's electron, carrier transfer, and optical properties. The observations indicate that the C2N/Mg(OH)2 heterojunction manifests a staggered band configuration, culminating in the accomplishment of a Z-type charge transfer paradigm. This mechanism promotes the recombination of e-h pairs within the C2N/Mg(OH)2 heterojunction, leading to the prolonged retention of photogenerated electrons in the Mg(OH)2 layer and photogenerated holes in the C2N layer. Consequently, this enables a sustained water reduction and oxidation reaction. The C2N/Mg(OH)2 heterojunction exhibits oxidation-reduction potentials that cross those of aqueous solutions under acidic (pH = 0) and neutral (pH = 7) conditions, thereby facilitating the photocatalytic process of water decomposition. Moreover, the optical absorption coefficient of the heterojunction surpasses that of a single two-dimensional material. Therefore, the direct Z-type C2N/Mg(OH)2 heterojunction holds promising potential as an exceptional photocatalyst for water decomposition.

Improved Fast Correlation Attacks on the Sosemanuk Stream Cipher

In this paper, we present a new algorithm for fast correlation attacks on stream ciphers with improved cryptanalysis results on the Sosemanuk stream cipher, one of the 7 finalists in the eSTREAM project in 2008. The new algorithm exploits the direct sum construction of covering codes in decoding phase which approximates the random vectors to a nearest codeword in a linear code. The new strategy provides large flexibility for the adversary and could reduce the time/memory/data complexities significantly. As a case study, we carefully revisit Sosemanuk and demonstrate a state recovery attack with a time complexity of 2134.8, which is 220 times faster than achievable before by the same kind of attack and is the fastest one among all known attacks so far. Our result indicates an inefficiency in longer keys than 135 bits and depicts that the security margin of Sosemanuk is around 28 for the 128-bit security for the first time.

Direct Construction of CZCS With Flexible Parameters for Channel Estimation in SM-MIMO System

Direct Construction of CZCS With Flexible Parameters for Channel Estimation in SM-MIMO System

Case study of the insulation performance in different types of flanking path construction

In many Asian countries, people often live in a high residential density environment due to the narrow land and dense population. As a result, It is common and unavoidable for noisy rooms and noise sensitive rooms to be adjacent (e.g., the audio-visual room is located under the living room of the upstairs residents). In order to improve sound insulation performance, feasible methods include improving direct and flanking sound transmission. Complete insulation performance research about has addressed different types of direct path construction in previous studies. However, to achieve higher insulation performance, the effect of the flanking path is key. The influence of the different flanking path constructions influence on sound transmission has rarely been explored. Therefore, this paper's objective is to study the overall insulation performance of different flanking path constructions (e.g., RC or lightweight construction), and the influence of adding additional layers. In this research, we focus on the vertical room pair situation and review direct and flanking path transmissions according to ISO 12354. Furthermore, we use the simulation software CadnaB to verify the influences of different types of construction, and then make a case in field measurements.

Brønsted Acid-Mediated Multicomponent One-Pot Approach to Direct Construction of 4-Aryl-hydrocoumarin Derivatives.

The facile and efficient synthesis of a unique class of 4-aryl-hydrocoumarins having enormous applications in medicinal chemistry and natural products is presented. We have for the first time developed a Brønsted acid-catalyzed, multicomponent, one-pot approach for producing various 4-aryl-coumarin derivatives. The feedstock availability of these precursors allowed access to a wide range of 2-chromanone derivatives in good to excellent yields under mild conditions. The practicality of this protocol was justified by the synthesis of bioactive compounds, late-stage functionalization of natural products, and gram-scale synthesis.

Categorizing possession in Zuanga-Yuanga and other Kanak languages (New Caledonia): a typological perspective

Abstract Like many other Oceanic and Kanak languages of New Caledonia, Zuanga-Yuanga [ZY] has classifiers restricted to the possession of nouns denoting food, drink, animals and plants; it also has dichotomous direct and indirect adnominal possessive constructions, which are generally labeled inalienable or alienable in the Oceanic literature. These terms refer to a distinction between close versus distant structural marking, which do not strictly correlate with lexical-semantic categories. For instance, kinship nouns are split over the two types of constructions, distinguishing reference from address kinship terms, not in terms of semantic distinctions between close versus distant kinship types. The split for body-part nouns is between directly possessed dedicated terms and indirectly possessed metaphorical body terms, not in terms of permanent versus removable parts, or temporary body properties. In ZY possessive constructions correlate with fairly strict possessee noun classes belonging to one single structural class (directly or indirectly marked). Only a limited number of nouns denoting parts-of-whole have alternate constructions expressing different semantic relations to the possessed noun.

Catalyst-Free Trans-Selective Oxyiodination and Oxychlorination of Alkynes Employing N-X (Halogen) Reagents.

β-halogenated enol esters and ethers are versatile building blocks in organic synthesis, which has attracted increasing attention. In this study, we report the facile trans-oxyiodination and oxychlorination of alkynes, leading to the direct construction of versatile halogenated enol esters and ethers. This transformation features an easy operation, optimal atomic economy, a strong functional group tolerance, broad substrate scope, and excellent trans-selectivity. Employing highly electrophilic bifunctional N-X (halogen) reagents was the key to achieving broad reaction generality. To our knowledge, this transformation represents the first oxyhalogenation system employing N-X (halogen) reagents as both oxylation and halogenation sources.

Directional verb constructions in Mandarin

Abstract In modern Chinese, a Directional Verb Construction (DVC) may contain either two or three verbs. DVCs with two verbs can be represented in three different ways, and DVCs with three verbs can be represented in four different ways. The different positions of the shared internal noun phrase (NP) argument result in divergent word orders of DVCs. Based on the Corpus of the United Daily News, this study discusses the syntax-pragmatic interface in Chinese DVCs within the framework of Role and Reference Grammar (RRG) with the intention of ascertaining how NP arguments are linked to syntax in DVCs, while at the same time accounting for what pragmatic factors play a role in determining constructional schemas for argument linking. The results show that different patterns of DVCs have different focus domains, and that the differential activation state of the internal NP argument plays an essential role in determining word order. Considering the correlation between activation state and focus domain, a highly activated internal NP tends to be linked to the position following the word bǎ or immediately following V1. In contrast, a least activated NP tends to be linked to the position immediately following V2 or V3.

Construction of New Hadamard Matrix Forms to Generate 4X4 and 8X8 Involutory MDS Matrices over GF (2m) for Lightweight Cryptography


 
 
 In this paper, we present the construction of two Hadamard matrix forms over GF(2m) to generate 4×4 and 8×8 involutory MDS (IMDS) matrices. The first form provides a straightforward way to generate 4×4 IMDS matrices, while the second is an efficient way to generate 8×8 IMDS matrices using a hybrid (combination of search-based methods and direct construction) approach. In addition, we propose an algorithm for computing the branch number of any non-singular matrix over GF(2m) and improve its computational complexity for Hadamard matrices. Using this algorithm and the proposed Hadamard matrix form, we obtain 2k ×2k lightweight involutory and non-involutory Hadamard MDS matrices with low XOR counts for k=2,3. Finally, we carry out a comparative study based on the XOR count to demonstrate that MDS matrices created using our Hadamard matrix forms have lower XOR counts than MDS matrices available in the literature as of today.
 
 

A direct construction of complete complementary code with zero correlation zone property for prime-power length

A direct construction of complete complementary code with zero correlation zone property for prime-power length