Use In Many Applications Research Articles

McBits revisited: toward a fast constant-time code-based KEM

This paper presents a constant-time fast implementation for a high-security code-based key encapsulation mechanism (KEM). The implementation is based on the “McBits” paper by Bernstein, Chou, and Schwabe in 2013: we use the same FFT algorithms for root finding and syndrome computation, similar algorithms for secret permutation, and bitslicing for low-level operations. As opposed to McBits, where a high decryption throughput is achieved by running many decryption operations in parallel, we take a different approach to exploit the internal parallelism in one decryption operation for the use of more applications. As a result, we manage to achieve a slightly better decryption throughput at a much higher security level than McBits. As a minor contribution, we also present a constant-time implementation for encryption and key-pair generation, with similar techniques used for decryption.

ONTOLOGY AND CLOUD COMUTING IN VARIOUS APPLICATIOND: THE SIGNIFICANCE AND MAJOR CHALLENGES

Nowadays, cloud computing having a significant and important impact in raising the capabilities dynamically without needs of any further funds to cover the training of new persons, investing in the new infrastructure, or taking license for new software. Add to these tangible privileges’, cloud computing expand the existing capabilities of IT in the last few years as well as grow from the concept of promising business to one of the fast growing segments of the information technology industry. So, the goal of this paper is to emphasize the importance of both ontology and cloud computing in various applications. Also, this article seeks to provide an overview on the use of cloud computing and the important benefits provided by the study of the most important challenges of cloud computing, and the steps that can be taken to mitigate the risks that may arise from use in many applications.

Direct Covalent Chemical Functionalization of Unmodified Two-Dimensional Molybdenum Disulfide

Two-dimensional semiconducting transition metal dichalcogenides (TMDCs) like molybdenum disulfide (MoS2) are generating significant excitement due to their unique electronic, chemical, and optical properties. Covalent chemical functionalization represents a critical tool for tuning the properties of TMDCs for use in many applications. However, the chemical inertness of semiconducting TMDCs has thus far hindered the robust chemical functionalization of these materials. Previous reports have required harsh chemical treatments or converting TMDCs into metallic phases prior to covalent attachment. Here, we demonstrate the direct covalent functionalization of the basal planes of unmodified semiconducting MoS2 using aryl diazonium salts without any pretreatments. Our approach preserves the semiconducting properties of MoS2, results in covalent C–S bonds, is applicable to MoS2 derived from a range of different synthesis methods, and enables a range of different functional groups to be tethered directly to the Mo...

Room-Temperature Lasing Action in GaN Quantum Wells in the Infrared 1.5 μm Region

Large-scale optoelectronics integration is strongly limited by the lack of efficient light sources, which could be integrated with the silicon complementary metal-oxide-semiconductor (CMOS) technology. Persistent efforts continue to achieve efficient light emission from silicon in the extending the silicon technology into fully integrated optoelectronic circuits. Here, we report the realization of room-temperature stimulated emission in the technologically crucial 1.5 micron wavelength range from Er-doped GaN multiple-quantum wells on silicon and sapphire. Employing the well-acknowledged variable stripe technique, we have demonstrated an optical gain up to 170 cm-1 in the multiple-quantum well structures. The observation of the stimulated emission is accompanied by the characteristic threshold behavior of emission intensity as a function of pump fluence, spectral linewidth narrowing and excitation length. The demonstration of room-temperature lasing at the minimum loss window of optical fibers and in the eye-safe wavelength region of 1.5 micron are highly sought-after for use in many applications including defense, industrial processing, communication, medicine, spectroscopy and imaging. As the synthesis of Er-doped GaN epitaxial layers on silicon and sapphire has been successfully demonstrated, the results laid the foundation for achieving hybrid GaN-Si lasers providing a new pathway towards full photonic integration for silicon optoelectronics.

Physicochemical properties of branched-chain dicationic ionic liquids

Dicationic ionic liquids (DILs) typically have higher viscosities and thermal stabilities than most conventional monocationic ionic liquids. However, due to their coulombic interactions, they often demonstrate higher melting points than conventional ILs which limit their use in many applications. Utilizing branched alkyl spacer chains between two cationic terminal groups resulted in dicationic ILs with lower melting points and therefore extended liquid ranges. A systematic investigation was conducted to determine how the position and type of substituent groups may affect the physicochemical properties of branched DILs. When compared to their linear counterparts, an increase in the kinematic viscosities and lower densities were observed for branched DILs. Thermal stability was found to be highly dependent on the position of the alkyl substituent group along with the length of the spacer chain. While the substitution on the α‑carbon of a spacer chain resulted in a significant decline in the thermal stability of DILs, the effect of mid-chain substitution on their stability was negligible. The performance testing of branched DILs as gas chromatography (GC) stationary phase displayed excellent separation of geometrical isomers in BTEX mixture.

Formulation of Poloxamers for Drug Delivery.

Poloxamers, also known as Pluronics®, are block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), which have an amphiphilic character and useful association and adsorption properties emanating from this. Poloxamers find use in many applications that require solubilization or stabilization of compounds and also have notable physiological properties, including low toxicity. Accordingly, poloxamers serve well as excipients for pharmaceuticals. Current challenges facing nanomedicine revolve around the transport of typically water-insoluble drugs throughout the body, followed by targeted delivery. Judicious design of drug delivery systems leads to improved bioavailability, patient compliance and therapeutic outcomes. The rich phase behavior (micelles, hydrogels, lyotropic liquid crystals, etc.) of poloxamers makes them amenable to multiple types of processing and various product forms. In this review, we first present the general solution behavior of poloxamers, focusing on their self-assembly properties. This is followed by a discussion of how the self-assembly properties of poloxamers can be leveraged to encapsulate drugs using an array of processing techniques including direct solubilization, solvent displacement methods, emulsification and preparation of kinetically-frozen nanoparticles. Finally, we conclude with a summary and perspective.

Photoactivation of Ligands for Extrinsically and Intrinsically Triggered Disassembly of Amphiphilic Nanoassemblies.

Specific response to the concurrent presence of two different inputs is one of the hallmarks of incorporating specificities in nature. Artificial nanoassemblies that concurrently respond to two very different inputs are of great interest in a variety of applications, especially in biomedicine. Here, we present a design strategy for amphiphilic nanoassemblies with such capabilities, enabled by photocaging a ligand moiety that is capable of binding to a specific protein. New molecular designs that offer nanoassemblies that respond to either of two inputs or only to the concurrent presence of two inputs are outlined. Such biomimetic nanoassemblies could find use in many applications, including drug delivery and diagnostics.

Glycerol Hydrogen-Bonding Network Dominates Structure and Collective Dynamics in a Deep Eutectic Solvent.

The deep eutectic solvent glyceline formed by choline chloride and glycerol in 1:2 molar ratio is much less viscous compared to glycerol, which facilitates its use in many applications where high viscosity is undesirable. Despite the large difference in viscosity, we have found that the structural network of glyceline is completely defined by its glycerol constituent, which exhibits complex microscopic dynamic behavior, as expected from a highly correlated hydrogen-bonding network. Choline ions occupy interstitial voids in the glycerol network and show little structural or dynamic correlations with glycerol molecules. Despite the known higher long-range diffusivity of the smaller glycerol species in glyceline, in applications where localized dynamics is essential (e.g., in microporous media), the local transport and dynamic properties must be dominated by the relatively loosely bound choline ions.

Engineering Biosensors with Dual Programmable Dynamic Ranges.

Although extensively used in all fields of chemistry, molecular recognition still suffers from a significant limitation: host-guest binding displays a fixed, hyperbolic dose-response curve, which limits its usefulness in many applications. Here we take advantage of the high programmability of DNA chemistry and propose a universal strategy to engineer biorecognition-based sensors with dual programmable dynamic ranges. Using DNA aptamers as our model recognition element and electrochemistry as our readout signal, we first designed a dual signaling "signal-on" and "signal-off" adenosine triphosphate (ATP) sensor composed of a ferrocene-labeled ATP aptamer in complex to a complementary, electrode-bound, methylene-blue labeled DNA. Using this simple "dimeric" sensor, we show that we can easily (1) tune the dynamic range of this dual-signaling sensor through base mutations on the electrode-bound DNA, (2) extend the dynamic range of this sensor by 2 orders of magnitude by using a combination of electrode-bound strands with varying affinity for the aptamers, (3) create an ultrasensitive dual signaling sensor by employing a sequestration strategy in which a nonsignaling, high affinity "depletant" DNA aptamer is added to the sensor surface, and (4) engineer a sensor that simultaneously provides extended and ultrasensitive readouts. These strategies, applicable to a wide range of biosensors and chemical systems, should broaden the application of molecular recognition in various fields of chemistry.

Fabrication and characterisation of ligand-functionalised ultrapure monodispersed metal nanoparticle nanoassemblies employing advanced gas deposition technique

Here, we report for the first time the fabrication of ligand-functionalised ultrapure monodispersed metal nanoparticles (Au, Cu, and Pt) from their pure metal precursors using the advanced gas deposition technique. The experimental conditions during nanoparticle formation were adjusted in order to obtain ultrafine isolated nanoparticles on different substrates. The morphology and surface analysis of the as-deposited metal nanoparticles were investigated using scanning electron microscopy, x-ray diffraction and Fourier transform infra-red spectroscopy, which demonstrated the formation of highly ordered pure crystalline nanoparticles with a relatively uniform size distribution of ∼10 nm (Au), ∼4 nm (Cu) and ∼3 nm (Pt), respectively. A broad range of organic ligands containing thiol or amine functional groups were attached to the nanoparticles to form continuous networks of nanoparticle-ligand nanoassemblies, which were characterised by scanning electron microscopy and x-ray photoelectron spectroscopy. The electrical resistance of the functional nanoassemblies deposited in the gap spacing of two microfabricated parallel Au electrodes patterned on silicon substrates ranged between tens of kΩ and tens of MΩ, which is suitable for use in many applications including (bio)chemical sensors, surface-enhanced Raman spectroscopy and molecular electronic rectifiers.

Superhydrophobic surfaces: a review on fundamentals, applications, and challenges

Superhydrophobicity is the tendency of a surface to repel water drops. A surface is qualified as a superhydrophobic surface only if the surface possesses a high apparent contact angle (>150°), low contact angle hysteresis (<10°), low sliding angle (<5°) and high stability of Cassie model state. Efforts have been made to mimic the superhydrophobicity found in nature (for example, lotus leaf), so that artificial superhydrophobic surfaces could be prepared for a variety of applications. Due to their versatile use in many applications, such as water-resistant surfaces, antifogging surfaces, anti-icing surfaces, anticorrosion surfaces etc., many methods have been developed to fabricate them. In this article, the fundamental principles of superhydrophobicity, some of the recent works in the preparation of superhydrophobic surfaces, their potential applications, and the challenges confronted in their new applications are reviewed and discussed.

A novel approach of an infrared transparent Er:Y2O3–MgO nanocomposite for eye-safe laser ceramics

Photoluminescence spectrum and energy levels of an Er:Y2O3–MgO nanocomposite.

Humanized Flies and Resources for Cross-Species Study.

The completion of whole-genome sequences has greatly broadened our understanding of genes and genomes. The availability of model organism databases facilitates the sharing of information. However, it is still challenging to predict the pathogenicity of missense mutations, and it is more difficult to evaluate the functional impact of noncoding variants. What is more, it is a primary question to understand what variants interact to express phenotypes. Powerful genetic tools and resources available in Drosophila now make it much easier to replace endogenous genes with exogenous DNA. This allows us to directly investigate and compare the functions of orthologs, variants, and fragments in a single genetic background, the value of which should be widely appreciated. To take one example, we are currently studying so-called ultra-conserved elements, which have been conserved over hundreds of millions of years of vertebrate evolution. Many highly conserved elements are in noncoding regions and are thought to play a pivotal role in gene regulation. We generated transgenic fly lines carrying human ultra-conserved elements for enhancer reporter assay and indeed observed the reporter expression in one or more tissues of embryos and larvae in all elements tested. Currently, transgenic human-ORF lines expressing human genes under the control of GAL4/UAS system are also been developed, which will greatly facilitate the cross-species in Drosophila. In this chapter, I introduce useful tools and resources available in Drosophila to nonspecialists, encouraging their further use in many applications.

Atomization of silver nanoparticles suspension as an alternative for generating nanosilver aerosol

Nanomaterials are highly attractive for use in many applications, primarily due to their greater contact surface area and enhanced effects compared to the corresponding bulk materials. However, nanomaterials present risks to human health, since they are able to penetrate deep into the respiratory tract. It is therefore important to know the particle sizes of these substances, although such measurements can present difficulties associated with the generation of this type of material. It is also important to investigate the mechanism of aerosol generation, considering the properties of the starting material. Here, evaluation was performed of the generation of an aerosol of silver nanoparticles from a suspension, using an environmentally friendly and simple synthesis method. A reduction reaction was used to produce the silver nanoparticles. The aerosol was generated using a modified nebulizer inhaler, and particles were counted using an SMPS system. The measurements showed that the predominant particle sizes were 45.63?2.49 nm (determined by SMPS) and 50.7?0.7 nm (determined by DLS analysis).

The evaporation kinetics of pure water droplets at varying drying rates and the use of evaporation rates to infer the gas phase relative humidity.

Numerous analytical models have been applied to describe the evaporation/condensation kinetics of volatile components from aerosol particles for use in many applications. However, the applicability of these models for treating cases that lead to substantial and rapid changes in particle temperature due to, for example, evaporative cooling remain to be compared with measurements. We consider three typical treatments, comparing predictions of the evaporation rates of pure water droplets over a wide range in gas phase relative humidity (RH) and exploring the sensitivity of the predictions to uncertainties in the thermophysical gas and condensed-phase parameters. We also compare predictions from the three treatments to measurements of the evaporation rates of pure water droplets with varying RH using an electrodynamic balance (EDB), concluding that only two of the model treatments are sufficiently able to account for the level of evaporative cooling (typically as high as 12 K). Finally, we show that the RH can be inferred accurately from the evaporation rate of pure water droplets over the full range in accessible RH and comparison with the model predictions (within absolute uncertainties of 2.5% RH over the range 20% to 95% RH), considering the level of agreement with independent measurements made through determining the equilibrated size of aqueous sodium chloride and sodium nitrate droplets.

Comparing competitive toughness to benchmark outcomes in retail oligopoly pricing

AbstractPast research on pricing in imperfectly competitive markets conventionally assumes that competition operates through a specific quantity or a price game. However, most markets do not function in a manner consistent with a single static benchmark. Methods to overcome this problem have largely been rejected by the research community (i.e., conjectural variations). The primary objective of our research is to introduce a new methodology for measuring imperfect competition under product differentiation in consumer goods. We develop the empirical procedures for estimating a competitive toughness model as proposed by d'Aspremont, Dos Santos Ferreira, and Gérard‐Varet. This approach presents a theoretically grounded procedure that measures market power in an empirically tractable framework. We estimate the proposed model on the retail market for ground coffee. Our results suggest that market power is understated in a model that imposes the restriction of Bertrand pricing. The results suggest that this could be a promising approach for use in many applications. [EconLit citations: D43, L13, K21]

Spatially‐Resolved Spectroscopic Characterization of Reflective and Transparent Materials at a Micro‐Meter Scale Using Coherence Scanning Interferometry

The development of new technologies and innovative products today is often accompanied by the emergence of new micro and nanomaterials. Due to their wider use in many applications, performing accurate characterization of these materials is becoming essential. The high performance of coherence scanning interferometry for materials characterization in terms of topographic, roughness and thickness measurements as well as for tomographic analysis of transparent layers has already been well demonstrated. However, demands regarding the spectral characterization of these materials requires new operation modes using the combination of spectral measurements with high resolution imaging. In this work we present a technique for local spectral measurements by careful processing of the entire interferometric signal over the scanned depth at each pixel in the image, so providing spatially resolved measurements in both the lateral and axial directions. Being a far‐field technique, and because the sample is illuminated with a white light source, spectral information is obtained over large areas (150 × 150 μm2) at the same time and for all the wavelengths. Spectroscopic mapping of a sample consisting of four different materials (Si, Al, Ag, Ti) and depth‐resolved measurements performed through a thin layer of PDMS are reported. Spectral measurements are made over an area of about 1–2 μm2, with an axial resolution of 1 μm, these features being dependent on the optical parameters of the system.

Airborne LiDAR Technology: A Review of Data Collection and Processing Systems

Airborne light detection and ranging (LiDAR) has now become industry standard tool for collecting accurate and dense topographic data at very high speed. These data have found use in many applications and several new applications are being discovered regularly. This paper presents a review of the current state-of-the-art of this technology. The paper covers both data capture and data processing issues of the technology. The paper first discusses various types of LiDAR sensors and their working. This is followed by information on data format and data quality assessment procedures. The paper reviews the existing data classification techniques and also looks into the new approaches like convolutional neural networks and visual analytics for data processing. Finally, the paper outlines future scope of the technology and the research challenges, which should be addressed in coming years.

EFFECT OF RUBBER POWDER PARTICLE ON THE STRENGTH OF FOAMED CONCRETE

Foamed concrete has become one of the most commercialized materials used in construction industry. It has different characteristics compared to conventional concrete such as self-compacting without vibration, flowability and low density. Even though foamed concrete has many advantages but it possess low strength limiting its use in many applications. This research aims to investigate the potential of foamed concrete incorporating rubber powder as additive to improve its strength. The amount of rubber powder added as filler in foamed concrete are 0%, 3%, 6%, 9% and 12%. A total of 15 concrete cubes and 15 concrete cylinders were cast with difference percentages of rubber powder in order to evaluate its compressive and splitting tensile strength. The mix design was set to achieve a density of 1800 kg/m3. The experiments on fresh state properties show that the foamed concrete has a very low workability as the percentage of rubber increase. However, the compressive and splitting tensile strengths for foamed concrete containing rubber are higher compared to control foamed concrete. The addition of 9% of rubber brought a significant increase for compressive strength and tensile strength of 122% and 43%, respectively, as compared to foamed concrete without rubber powder. Based on the results, it was concluded that the optimum percentage of rubber in this research was 9% for the highest compressive and tensile strength for foamed concrete.

Hemocompatibility of hyaluronan enhanced linear low density polyethylene for blood contacting applications.

Despite their overall success, different blood-contacting medical devices such as heart valves, stents, and so forth, are still plagued with hemocompatibility issues which often result in the need for subsequent replacement and/or life-long anticoagulation therapy. Consequently, there is a significant interest in developing biomaterials that can address these issues. Polymeric-based materials have been proposed for use in many applications due to their ability to be finely tuned through manufacturing and surface modification to enhance hemocompatibility. In this study, we have developed a novel, hydrophilic biomaterial comprised of an interpenetrating polymer network (IPN) of hyaluronan (HA) and linear low density polyethylene (LLDPE). HA is a highly lubricous, anionic polysaccharide ubiquitously found in the human body. It is currently being investigated for a vast array of biomedical applications including cardiovascular therapies such as hydrogel-based regenerative cell therapies for myocardial infarction, HA-coated stents, and surface modifications of polyurethane and metals for use in blood-contacting implants. The aim of this study was to assess the in vitro thrombogenic response of the hydrophilic polymer surface, HA-LLDPE for future potential use as flexible heart valve leaflets. The results indicate that HA-LLDPE is non-toxic and reduces thromobogenicity as compared to LLDPE surfaces, asserting its feasibility for use as a blood-contacting biomaterial. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1964-1975, 2018.