METALLOLES-14 CHEMISTRY

Abstract

In order to obtain β-functionalized 1-sila (or germa)-cyclopent-2-enes (M = Si, Ge; R¹, R² = Me or Ph; R³, R⁴ = H or Me) (I) various oxidation methods of metallacyclopent-3-enes have been examinated. The resulting metallacyclopent-4-ene-3-ols (I, X = OH) were converted into phenylcarbamates (I = OC(O)NHPh) or S-methylxanthates (I = OC(S)SMe) and their utility as intermediates in the synthesis of metalloles (siloles and germoles) was investigated.

Depending on the experimental conditions, catalytic dehydration of metallacyclopentenols or thermolysis of carbamates or xanthates give various dienes via four different reaction processes: i) β-elimination C-M; ii) β-elimination C-H; iii) isomerization of C-methylated metalloles; iv) catalytic demetallation.

The thermolysis of arylcarbamates is the best method for conversion of I to metalloles, specially for the synthesis of remarkably dimerization-stable 1,1-R¹R²-3,4-dimethylmetalloles (≥ 80% yield). A one pot synthesis of these stable metalloles from the corresponding alcohol and phenyl isocyanate is proposed.

Unstable monomeric metalloles are stabilized by transition metal complexes or trapped by a (4 + 2) cycloaddition.     

Deterioration of hardened cement paste under combined sulphate-chloride attack investigated by synchrotron XRD

The exact mechanisms of the phase transitions caused by a combined sulphate-chloride attack are discussed controversially. The main points concern the mutual influences of sulphate and chloride ions during the secondary binding processes of these anions within cement hydrate phases. We simulated combined sulphate-chloride attack under laboratory conditions using solutions containing NaCl and Na₂SO₄ in different concentrations. Three sample compositions were used for the preparation of the specimens. In two of them, 30% of Portland cement was replaced by supplementary cementitious materials (fly ash, slag).The phase distribution in the samples was determined using synchrotron X-ray diffraction. The analysis with high spatial resolution allows the localisation of the secondary phase formation in the microstructural profile of the sample. A mechanism of the phase developments under combined sulphate-chloride attack is derived.     

Cryptanalysis and Improvement of Quantum Private Comparison Protocol Based on Bell Entangled States

Recently, Liu et al. [Commun. Theor. Phys. 57 (2012) 583] proposed a quantum private comparison protocol based on entanglement swapping of Bell states, which aims to securely compare the equality of two participants' information with the help of a semi-honest third party (TP). However, the present study points out there is a fatal loophole in Liu et al.'s protocol, and TP can make Bell-basis measurement to know all the participants' secret inputs without being detected. To fix the problem, a simple solution, which uses one-time eavesdropper checking with decoy photons instead of twice eavesdropper checking with Bell states, is demonstrated. Compared with the original protocol, it not only reduces the Bell states consumption but also simplifies the protocol steps.     

Counteracting a Saturation Attack in Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Filter Embedded in Homodyne Detector

A saturation attack can be employed for compromising the practical security of continuous-variable quantum key distribution (CVQKD). In this paper, we suggest a countermeasure approach to resisting this attack by embedding an adjustable optical filter (AOF) in the CVQKD system. Numerical simulations illustrate the effects of the AOF-enabled countermeasure on the performance in terms of the secret key rate and transmission distance. The legal participants can trace back the information that has been eavesdropped by an attacker from the imperfect receiver, which indicates that this approach can be used for defeating a saturation attack in practical quantum communications.     

ABCAttack: A Gradient-Free Optimization Black-Box Attack for Fooling Deep Image Classifiers

The vulnerability of deep neural network (DNN)-based systems makes them susceptible to adversarial perturbation and may cause classification task failure. In this work, we propose an adversarial attack model using the Artificial Bee Colony (ABC) algorithm to generate adversarial samples without the need for a further gradient evaluation and training of the substitute model, which can further improve the chance of task failure caused by adversarial perturbation. In untargeted attacks, the proposed method obtained 100%, 98.6%, and 90.00% success rates on the MNIST, CIFAR-10 and ImageNet datasets, respectively. The experimental results show that the proposed ABCAttack can not only obtain a high attack success rate with fewer queries in the black-box setting, but also break some existing defenses to a large extent, and is not limited by model structure or size, which provides further research directions for deep learning evasion attacks and defenses.     

Polarization Attack on Continuous-Variable Quantum Key Distribution with a Local Local Oscillator

The estimation of phase noise of continuous-variable quantum key distribution protocol with a local local oscillator (LLO CVQKD), as a major process in quantifying the secret key rate, is closely relevant to the intensity of the phase reference. However, the transmission of the phase reference through the insecure quantum channel is prone to be exploited by the eavesdropper (Eve) to mount attacks. Here, we introduce a polarization attack scheme against the phase reference. Presently, in a practical LLO CVQKD system, only part of the phase reference pulses are measured to compensate for the polarization drift of the quantum signal pulses in a compensation cycle due to the limited polarization measurement rate, while the other part of the phase reference pulses are not measured. We show that Eve can control the phase noise by manipulating the polarization direction of the unmeasured phase reference to hide her attack on the quantum signal. Simulations show that Eve can obtain partial or total key rates information shared between Alice and Bob as the transmission distance increases. Improving the polarization measurement rate to 100% or monitoring the phase reference intensity in real-time is of great importance to protect the LLO CVQKD from polarization attack.     

A Word-Granular Adversarial Attacks Framework for Causal Event Extraction

As a data augmentation method, masking word is commonly used in many natural language processing tasks. However, most mask methods are based on rules and are not related to downstream tasks. In this paper, we propose a novel masking word generator, named Actor-Critic Mask Model (ACMM), which can adaptively adjust the mask strategy according to the performance of downstream tasks. In order to demonstrate the effectiveness of the method, we conducted experiments on two causal event extraction datasets. Experiment results show that, compared with various rule-based masking methods, the masked sentences generated by our proposed method can significantly enhance the generalization of the model and improve the model performance.     

基于Arnold变换的图像置乱密码的安全性分析

研究了基于Arnold变换的图像置乱算法的安全性问题.该算法使用两个不同的Arnold变换矩阵,分别对明文图像进行一次全局置乱和一次分割置乱.结果分析表明,该算法的密钥空间小,不足以抵抗穷举密钥攻击.在选择明文攻击下,导出了两次Arnold变换等效密钥之间的确定性关系.这一关系有效地降低了整个密码系统的密钥空间,从而可以用较小的计算代价获得密钥.理论和实验结果均表明,该密码系统不够安全.     

线导+尾流自导鱼雷的有效射击可行域

基于线导+尾流自导鱼雷的弹道特点和末端尾流进入角的使用限制,选用Runge-Kutta方法,得出线导+尾流自导鱼雷在不同尾流进入角和不同射距时的弹道轨迹,进而分析并解算出线导+尾流自导鱼雷有效射击可行域.方法对自导鱼雷有效射击可行域解算方法进行了较大改进,能更好地满足线导+尾流自导鱼雷作战使用时射击阵位点选择需求.     

多个接收者认证码的信息论下界及其组合特征

对一般的（带保密的）多个接收者认证码进行了讨论,给出了这类认证码的ｒ阶欺骗攻击成功概率的信息论下界,并利用部分平衡ｔ－设计和狭义区组设计刻划了达到信息论下界的多个接收者认证码的组合特征。