Searchable functionality is provided in many online services such as mail services or outsourced data storage. To protect users privacy, data in these services is usually stored after being encrypted using searchable encryption. This enables the data user to securely search encrypted data from a remote server without leaking data and query information. Public key encryption with keyword search is one of the research branches of searchable encryption; this provides privacy-preserving searchable functionality for applications such as encrypted email systems. However, it has an inherent vulnerability in that the information of a query may be leaked using a keyword guessing attack. Most of existing works aim to make the system resistant to offline keyword guessing, but this does not protect against online attacks on real world services. In this paper, we move a step forward to present a generic framework able to resist online keyword guessing attack using a server-assisted model. Specifically, we design a novel primitive C mirrored all-but-one lossy encryption, which can prevent a specific user from generating valid encryptions. This primitive can be seen as an access control on encryption ability. Combining searchable encryption technique with the new primitive makes online keyword guessing attack impossible for the specified user, even if the attack is launched online. We further give formal security analysis for the generic framework, and a concrete implementation with efficiency analysis to show that our design is practical.

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H ₂ O ₂ , is an attractive oxidant for synthetic chemistry, especially if activated as percarboxylic acid. H ₂ O ₂ , however, is also a potent inactivator of enzymes. Protein engineering efforts to improve enzyme resistance against H ₂ O ₂ in the past have mostly focused on tedious probabilistic directed evolution approaches. Here we demonstrate that a rational approach combining multiscale MD simulations and Born-Oppenheimer ab initio QM/MM MD simulations is an efficient approach to rapidly identify improved enzyme variants. Thus, the lipase from Penicillium camembertii was redesigned with a single mutation (I260R), leading to drastic improvements in H ₂ O ₂ resistance while maintaining the catalytic activity. Also the extension of this methodology to other enzymes is demonstrated.

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Poor H ₂ O ₂ -resistance by enzymes is a key bottleneck in the epoxidation process of oil by enzymatic methods. In this study, the stability of three lipases, from Aspergillus oryzae lipase (AOL), Aspergillus fumigatus lipase B (AflB), and marine Janibacter (MAJ1), in the presence of H ₂ O ₂ was evaluated in different types of natural deep eutectic solvents (NADES). This stability was strengthened significantly in the NADES compared to the buffer. Specifically, AOL retained 84.7% of its initial activity in the presence of choline chloride/sorbitol (1:1 M ratio) and 3 mol L ⁻¹ H ₂ O ₂ after 24 h incubation at 40°C. In addition, the two-phase epoxidation process was optimized with AOL in ChCl/sorbitol to reach up to 96.8% conversion under the optimized conditions (molar ratio of octanoic acid/H ₂ O ₂ /C=C-bonds = 0.3:1.5:1, enzyme loading of 15 U g ⁻¹ of soybean oil, ChCl/sorbitol content of 70.0% of the weight of hydrophilic phase, and reaction temperature of 50°C). Moreover, the lipase dispersed in NADES retained approximately 66% of its initial activity after being used for seven batch cycles. Overall, NADES-based enzymatic epoxidation is a feasible and promising strategy for the synthesis of epoxidized oils.

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α‐Linolenic acid‐rich diacylglycerol has been demonstrated with promising health promotion functions. This study examined the production, immobilization of lipase PCL, and its application in the synthesis of diacylglycerol by esterification of α‐linolenic acid with glycerol. The resin ECR8806 was selected as an effective support for the immobilization of lipase PCL. Fourier transform infrared and Laser scanning confocal microscope analysis proved that the lipase was successfully immobilized on the resin. Compared with the free PCL, the immobilized one exhibited higher temperature tolerance. Under optimized reaction conditions, a DAG content of 54.49% were obtained. After further purified by molecular distillation, the purity of DAG was up to 99.28%. During esterification, the immobilized PCL was quite stable and retained more than 91.60% of its initial activity after 10 cycles. These new findings on the immobilized PCL will make it to be a prospective enzyme in oils and fats industry. @en

A chemoenzymatic method for the production of epoxidized vegetable oils was developed. The unique combination of the commercial lipase G from Penicillieum camembertii with certain deep eutectic solvents enabled the efficient production of epoxidized vegetable oils.

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A Ser105Ala mutant of the lipase B from Candida antarctica enables 'perhydrolase-only' reactions. At the example of the chemoenzymatic Baeyer-Villiger oxidation of cyclohexanone, we demonstrate that with this mutant selective oxidation can be achieved in deep eutectic solvent while essentially eliminating the undesired hydrolysis reaction of the product.

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Epoxides are important synthetic intermediates for the synthesis of a broad range of industrial products. This study presents a promising solution to the current limitation of enzyme instability. By using simple deep eutectic solvents such as choline chloride/sorbitol, significant stabilization of the biocatalyst has been achieved leading to more robust reactions while using environmentally more acceptable solvents as compared to ionic liquids.

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With the continuous scaling of CMOS VLSI technology well into the nano-meter regime, and the increasing demand for ultra low power/low voltage circuits and systems, reliability is becoming an extra design optimisation goal in addition to size, performance, and energy. In this paper, a supply voltage Vdd-) dependent, transistor threshold voltage variation aware propagation delay estimation model and a comprehensive statistical model to evaluate the reliability of the VLSI circuits is proposed. This accurate Vdd-dependent reliability evaluation model can be applied in the process of reliability driven multi-objective optimisation, which deals with tradeoffs between reliability, area, performance and energy. The experimental results show that the average estimation error is within 3% when compared to Monte-Carlo SPICE simulation while saving runtime by at least 100 times for generic enchmark circuits. @en

The continuous transistor scaling and extremely lower power constraints in modern VLSI chips can potentially supersede the benefits of the technology shrinking due to reliability issues. Due to external aggression factors, e.g., radiation and temperature gradients, the CMOS devices flawless functioning cannot be guaranteed any more. Thus, design time Integrated Circuits (ICs) reliability assessment is now turning out to be a mandatory step in the IC design flow. In this work, we present a novel CAD analytical error/reliability propagation analysis technique called Conditional Probabilistic Error/Reliability Propagation Analysis (CPERPA) algorithm. CPERPA efficiently resolves reliability related correlations including reconvergent fanouts and related errors, using a condition algorithm originating from the conditional probability theory, which promotes the accuracy at the expense of relatively low complexity enhancement. Experimental results on several benchmark circuits demonstrate the accuracy and the simulation time advantages of our approach when compared to Monte-Carlo simulations. The results obtained with the proposed CPERPA framework are within 3% average error and up to 1000 times faster when compared to Monte-Carlo simulations.@en