Directed Evolution of an Antitumor Drug (Arginine Deiminase PpADI) for Increased Activity at Physiological pH

Arginine deiminase (ADI; EC 3.5.3.6) has been studied as a potential antitumor drug for the treatment of arginine‐auxotrophic tumors, such as hepatocellular carcinomas (HCCs) and melanomas. Studies with human lymphatic leukemia cell lines confirmed that ADI is an antiangiogenic agent for treating leukemia. The main limitation of ADI from Pseudomonas plecoglossicida (PpADI) lies in its pH‐dependent activity profile, its pH optimum is at 6.5. A pH shift from 6.5 to 7.5 results in an approximately 80 % drop in activity. (The pH of human plasma is 7.35 to 7.45.) In order to shift the PpADI pH optimum, a directed‐evolution protocol based on an adapted citrulline‐screening protocol in microtiter‐plate format was developed and validated. A proof of concept for ADI engineering resulted in a pH optimum of pH 7.0 and increased resistance under physiological and slightly alkaline conditions. At pH 7.4, variant M2 (K5T/D44E/H404R) is four times faster than the wild‐type PpADI and retains ～50 % of its activity relative to its pH optimum, compared to ～10 % in the case of the wild‐type PpADI.     

Intensifying Heat Using MOF-Isolated Graphene for Solar-Driven Seawater Desalination at 98% Solar-to-Thermal Efficiency

Photothermal materials are crucial for diverse heating applications, but it remains challenging to achieve high energy conversion efficiency due to the difficulty to concurrently improve light absorbance and suppress heat loss. Herein, a zeolitic imidazolate framework-isolated graphene (G@ZIF) nanohybrid is demonstrated that utilizes ultrathin, heat-insulating ZIF layers, and G@ZIF interfacial nanocavity to synergistically intensify light absorbance and heat localization. Under artificial sunlight illumination (≈1 kW m⁻²), the G@ZIF film attains a maximum temperature of 120 °C in an open environment with a 98% solar-to-thermal conversion efficiency. Importantly, the porous ZIF layer allows small molecules/media to enter and access the embedded hot graphene surface for targeted heat transfer in practical applications. As a proof-of-concept, the G@ZIF-based steam generator realizes 96% energy conversion from light to vapor with near-perfect desalination and water purification efficiencies (>99.9%). This design is generic and can be extended to other photothermal systems for advanced solar-thermal applications, including catalysis, water treatments, sterilization, and mechanical actuation.     

Suboptimal SISO decoding of systematic binary algebraic block codes

Previous work on concatenated single parity-check codes has yielded exceptionally good performance despite, or perhaps because of, their weak algebraic structure. In this article, maximum a posteriori single parity-check decoders are applied to the decoding of systematic binary algebraic block codes. Results for a range of Hamming codes show good performance compared to soft-decision brute force (maximum-likelihood) and algebraic decoding. The decoding complexity of the proposed technique grows only linearly with increasing block length.     

Array interconnection for rearrangeable 2-D MEMS optical switch

Two-dimensional (2-D) microelectromechanical systems (MEMS) optical switches can be constructed by arranging the MEMS-actuated micromirrors as an array. We consider here the switching capability, routing, and optimization of the rectangular array interconnection on which the capability and efficiency of 2-D MEMS switches depend. The switching capability of a rectangular array is proved analytically. Two routing algorithms, namely, the most-bend routing and the least-bend routing, are developed, which, respectively, maximize and minimize the number of 2 /spl times/ 2 switches in the "bend" state. A method of counting the number of permutations realizable with a given number of switches in the "bend" state is proposed to evaluate the performance of both routing schemes. The understanding of the underlying interconnection pattern enables us to study the problem of constructing rearrangeable optical switches of arbitrary size.     

Roles of Calcium,Zinc, Copper and Titanium Compounds on the Degradation of Polymers

In this article, the influences of the metallic filler content upon the thermal degradability of polymer composites such as initial degradation temperature, maximum degradation temperature and char content have been critically reviewed using thermogravimetric analysis. Besides that, the review on the relationship between activation energies of polymer/metal composites, which was obtained from various degrade models, and the content of metallic fillers have also been defined. Other thermal properties such as glass transition temperature (T_g) and melting temperature (T_m) have also been reviewed based on the evaluation of differential scanning calorimetry (DSC) analysis.     

Synthesis,characterization and biophysical evaluation of the 2D Ti2CTx MXene using 3D spheroid-type cultures

MXenes are novel 2-D materials which have been extensively investigated for use in advanced biocomposites, water purification, biosensors, bioimaging and antibacterial systems. However, the knowledge associated with the mechanism of cytotoxic response is still limited to lack of verification against 3D spheroid-type cultures. Herein, we present a report on the in vitro cytotoxicity of Ti₂CT_x MXene against cervical cancer cell lines (HeLa) in a form of 3D spheroid with comparison to 2D cell culture system. Ti₂CT_x MXenes can be characterized by their multi-layered structure that is produced by the efficient elimination of Al and appearance of the surface functional groups. The biological results with 2D and 3D HeLa indicated that the Ti₂CT_x MXene was moderately cytotoxic to cells and the cytotoxicity was dose dependent. Our results showed that the toxicity of MXenes is potentially due to direct contact of the Ti₂CT_x MXene with the cell membrane wall. The Raman spectra suggested that the Ti₂CT_x MXenes interfered with the cytoplasmic proteins’ conformation and the surrounding microenvironment. This inherently modified the biochemistry of the cell membrane and caused cell apoptosis. This paper contributes to the pool of knowledge regarding the biocompatibility and biophysical properties of Ti₂CT_x MXene.     

PalmHashing: a novel approach for cancelable biometrics

We propose a novel cancelable biometric approach, known as PalmHashing, to solve the non-revocable biometric issue. The proposed method hashes palmprint templates with a set of pseudo-random keys to obtain a unique code called palmhash. The palmhash code can be stored in portable devices such tokens and smartcards for verification. Multiple sets of palmhash codes can be maintained in multiple applications. Thus the privacy and security of the applications can be greatly enhanced. When compromised, revocation can also be achieved via direct replacement of a new set of palmhash code. In addition, PalmHashing offers several advantages over contemporary biometric approaches such as clear separation of the genuine-imposter populations and zero EER occurrences. In this paper, we outline the implementation details of this method and also highlight its potentials in security-critical applications.     

Ultrasensitive label-free DNA analysis using an electronic chip based on carbon nanotube nanoelectrode arrays

We report the detection of DNA PCR amplicons using an ultrasensitive label-free electronic technique based on multiwalled carbon nanotube (MWNT) nanoelectrode arrays embedded in an SiO(2) matrix. Specific PCR amplicons are reliably detected using electrochemical (EC) methods through allele-specific oligonucleotide hybridization. The inherent guanine bases in the DNA amplicon target of [Formula: see text] bases serve as signal moieties with the aid of Ru(bpy)(3)(2+) mediators, providing an amplified anodic current associated with the oxidation of guanine groups at the nanoelectrode surface. The reduced size and density of the nanoelectrode array provided by MWNTs dramatically improves the sensitivity of EC detection. In addition, the abundant guanine bases in target DNA produce a large signal. Less than [Formula: see text] target amplicons can be detected on a microspot, approaching the sensitivity limit of conventional laser-based fluorescence techniques. This method also eliminates the labelling requirement and makes the measurements much simpler. This platform can be employed for developing highly automated electronic chips with multiplex nanoelectrode arrays for quick DNA analysis.