PBX炸药粘弹性统计微裂纹本构模型的改进

基于描述PBX炸药本构关系的粘弹性统计微裂纹模型(Visco-SCRAM),通过修正其微裂纹方向矢量的取值范围、初始缺陷尺寸和体量本构关系,得到模型的改进形式。将改进的模型嵌入有限元程序中,开展PBX炸药JO-9159的平板撞击实验数值模拟研究,讨论了微裂纹数密度参数对计算结果的影响。结合实测曲线,对模型改进前、后的计算结果进行对比和分析。结果表明,改进的模型能够更合理地描述低速冲击下PBX炸药的损伤和破坏。     

基于扩展度的复杂网络传播影响力评估算法

对网络中节点的传播影响力进行评估具有十分重要的意义, 有助于促进有益或抑制有害信息的传播. 目前, 多种中心性指标可用于对节点的传播影响力进行评估, 然而它们一般只有当传播率处于特定范围时才能取得理想的结果. 例如, 度值中心性指标在传播率较小时较为合适, 而半局部中心性和接近中心性指标则适用于稍大一些的传播率. 为了解决各种评估指标对传播率敏感的问题, 提出了一种基于扩展度的传播影响力评估算法. 算法利用邻居节点度值叠加的方式对节点度的覆盖范围进行了扩展, 使不同的扩展层次对应于不同的传播率, 并通过抽样测试确定了适合于特定传播率的层次数. 真实和模拟数据集上的实验结果表明, 通过扩展度算法得到的扩展度指标能在不同传播率下对节点的传播影响力进行有效评估, 其准确性能够达到或优于利用其他中心性指标进行评估的结果.     

One‐Pot Regioselective Synthesis of Novel Oximino Ester‐Containing 1‐Aryl‐4‐chloro‐3‐oxypyrazoles as Potential Fungicides

A novel, functional‐group‐tolerant, and highly regioselective one‐pot synthesis of six 4‐chloro‐1‐aryl‐3‐oxypyrazoles, 8a – 8f , containing an oximino ester moiety has been developed. Their structures were characterized by ¹H‐ and ¹³C‐NMR, IR, MS, and elemental analyses. The regioselectivity of the reaction was also determined by single‐crystal X‐ray diffraction analysis of product 8d . The reaction pathway, proposed with the aid of DFT calculations, likely proceeds via a DMF‐catalyzed mechanism, which involves an electrophilic attack by SOCl₂ and two nucleophilic substitutions by benzyl bromide (BnBr) and Cl^?, respectively, as the key steps. A preliminary in vitro bioassay indicated that most compounds exhibited good fungicidal activities against Sclerotinia sclerotiorum and Gibberella zeae. Especially, 8d and 8e displayed higher or similar fungicidal activities compared with pyraclostrobin at the concentration of 10 μg/ml.     

Synthesis and Biological Activities of 3‐Substituted Analogues of Tenuazonic Acid

A series of tenuazonic acid analogues in which the acetyl group was replaced with electron‐withdrawing substituents have been synthesized with the aim of obtaining molecules with various bioactivities. Substituents such as cyano, sulfonyl, and amido were introduced at the 3‐position of the pyrrolidine‐2,4‐dione nucleus of tenuazonic acid. 3‐Cyano and sulfonyl pyrrolidine‐2,4‐dione compounds ( 2 and 6 ) were prepared via a Dieckmann cyclization as key step. 3‐Amido pyrrolidine‐2,4‐dione compounds ( 9 ) were prepared by a microwave‐assisted amidation reaction from corresponding 3‐carboxylate derivative. The target compounds were evaluated; their herbicidal, fungicidal, and insecticidal activities, and the preliminary bioassay data showed that some 3‐cyanopyrrolidine‐2,4‐diones 2 gave good insecticidal activity, whereas some 3‐amido compounds 9 exhibited moderate to strong fungicidal activity against Pythium dissimile at 20 mg/L.     

Study of 1,3‐Dipolar Cycloaddition and Ring Contraction of New 1,4‐Phenylene‐bis[1,5]benzothiazepine Derivatives

Some 1,4‐phenylene‐bis[1,2,4]oxadiazolo‐[5,4‐d][1,5]benzothiazepine derivatives ( 4a , 4b , 4c ) were synthesized by 1,3‐dipolar cycloaddition reaction of benzohydroximinoyl chloride with 1,4‐phenylene‐bis(4‐aryl)‐2,3‐dihydro[1,5]benzothiazepine ( 2a , 2b , 2c ); meanwhile, compounds 2a , 2b , 2c also occurred ring contraction under acylating condition to obtain bis[2‐aryl‐2′‐(β‐1,4‐phenylenevinyl)‐3‐acetyl]‐2,3‐dihydro[1,5]benzothiazoles ( 3a , 3b , 3c ). The structures of some novel compounds were confirmed by IR, ¹H‐NMR, elemental, and X‐ray crystallographic analysis.     

Improved and Efficient Synthesis of Pyrrolo[2,3,4‐kl]acridin‐1‐one Derivatives under Ultrasound Irradiation

A improved and efficient procedure for the synthesis of pyrrolo[2,3,4‐kl]acridin‐1‐one derivatives via the reaction of isatin and enaminone catalyzed by ceric ammonium nitrate under ultrasonic condition has been developed. Compared with the conventional methods, the remarkable advantages of this method are mild reaction conditions, operational simplicity, higher yield, and shorter reaction times.     

Synthesis of Novel Tricyclic 1,5‐Benzothiazepine Derivatives Bearing Quinoline Moiety via [2 + 2] Cycloaddition Reaction

A series of new tricyclic 1,5‐benzothiazepine derivatives were synthesized by the reaction of 1,5‐benzothiazepine containing 2‐phenoxy‐quinoline with chloracetyl chloride and phenoxyacetyl chloride. The structures of the target compounds were confirmed by IR, ¹H NMR MS, and elemental analysis.     

An Efficient Synthesis of Isoxazoles and Pyrazoles under Ultrasound Irradiation

A series of 5‐arylisoxazole and 5‐aryl‐1H‐pyrazole derivatives was synthesized by the reaction of 3‐(dimethylamino)‐1‐arylprop‐2‐en‐1‐one with hydroxylamine hydrochloride or hydrazine hydrate under ultrasound irradiation without using any catalyst. This method has the advantages of easier work‐up, mild reaction condition, high yields, shorter reaction time, and environmentally benign procedure.     

Investigation on Photophysical Properties of D–π–A–π–D‐Type Fluorenone‐Based Linear Conjugated Oligomers by Using Femtosecond Transient Absorption Spectroscopy

The effects of π‐spacer and electron donor groups on the photophysical behaviors of fluorenone‐based linear conjugated oligomers have been systemically investigated. Solvent‐dependent steady‐state measurements exhibit that the fluorene vinylene (FV) spacer and the electron‐donating ability of donor group are able to modulate the spectral features of oligomers and the fluorescence quantum yield could decrease with the increasing of the solvent polarity. Meanwhile, quantum chemical calculation simulates their absorption spectra, and analyzes their electron transition components simultaneously. The transient absorption measurements focus on the photoexcitation dynamics of these oligomers in the toluene solution, which show that an intramolecular charge transfer state exists in the relaxation process of excited states, and its generation process could accelerate with the introduction of FV spacer and the enhancement of donor strength.     

Investigation on “Excimer” Formation Mechanism of Linear Oligofluorenes‐Functionalized Anthracenes by Using Transient Absorption Spectroscopy

We study the photophysical characters of two oligofluorenes‐functionalized anthracenes molecules with different fluorine‐vinylene (FV) units, which exhibits that “excimer” state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of “excimer”. The fast one is controlled by the arene‐arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM‐dependent “excimer” and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution.