Microfluidic emulsion-templating offers the preparation of functional microcapsules with tunable compositions and structures that are otherwise inaccessible using conventional methods. However, the inherent nature of emulsions relying on the immiscibility of phases comprising the emulsion limits the use of a single platform for the realization of microcapsules with diversity in shell materials. Herein, fluorocarbon oil-based triple emulsions are utilized as templates to achieve microcapsule diversity through a single platform. By introducing fluorocarbon oil with omniphobicity as the interstitial phase between the core and the shell phase, additional degrees of freedom are provided in the library of shell materials applicable in the design of functional microcapsules. Moreover, it is demonstrated that surfactant complexation at the emulsion interface effectively enhances the stability of the emulsion. This grants the use of various solidification methods including polymerization, freezing, and even solvent removal without delicate control of spreading coefficients or complex surfactant synthesis processes. The showcased microcapsule diversity signifies pivotal breakthroughs in microencapsulation technologies, illustrating how the synergistic use of fluorocarbon oil and interfacial complexation of surfactants in emulsions provides true freedom in universal microcapsule shell design for various applications including cosmetics, food, drug delivery, and cell therapy to name a few.

Microfluidic technology widely used in generating monodisperse emulsion droplets often suffers from complexity, scalability, applicability to practical fluids, as well as operation instability due to its susceptibility to flow perturbations, low clearance, and depletion of surfactants. Herein, we present a monolithic 3D-printed step-emulsification device (3D-PSD) for scalable and robust production of high viscosity emulsion droplets up to 208.16 mPa s, which cannot be fully addressed using conventional step-emulsification devices. By utilizing stereo-lithography (SLA), 24 triangular nozzles with a pair of 3D void flow distributors are integrated within the 3D-PSD to ensure uniform flow distribution followed by monodisperse droplet formation. The outlets positioned vertically downward enables gravity-assisted clearing to prevent droplet accumulation and thereby maintain size monodispersity. Deposition of silica nanoparticles (SiNP) within the device was also shown to alter the surface wettability from hydrophobic to hydrophilic, enabling the production of both water-in-oil (W/O) as well as oil-in-water (O/W) emulsion droplets, operated at a maximum production rate of up to 50 mL h-1. The utility of the device is further verified through continuous production of biodegradable polycaprolactone (PCL) microparticles using O/W emulsion as templates. We envision that the 3D-PSD presented in this work marks a significant leap in high-throughput production of high viscosity emulsion droplets as well as the particle analogs. A monolithic 3D-printed step-emulsification device is fabricated for scalable and robust production of high viscosity droplets.

On the thermomechanical treatments of Cu-Ni-Si alloy, cold-rolling (CR) before solution heat treatment (SHT) is commonly conducted to eliminate defects in a casting slab. In addition, a rolling is applied to reduce/adjust the thickness of casting slab before SHT. In a heavily deformed microstructure by CR, on the other hand, grain growth during a heating in SHT is likely to occur as the result of recrystallization. In general, tensile strength and fatigue strength tend to decrease with an increase in the grain size. However, the effect of difference in grain sizes produced by with and without CR before SHT on the fatigue strength is unclear. In the present study, fatigue tests of Cu-6Ni-Si alloy smooth specimens with a grain fabricated through different thermomechanical processes were conducted. The fatigue behavior of Cu-Ni-Si alloy was discussed.

In article number 2007392, Pil J. Yoo, Min Jun Oh, and Je Hyun Lee report graphene-based ultralight foams for thermal insulation. Through the close-packed integration of thin microbubbles of graphene, entirely non-directional and closed cellular structures (CCS) are created. These isotropic CCS foams exhibit extremely low thermal conductivity (5.75 mW m−1 K−1) thanks to the efficient suppression of solid and gas conduction in heat transport.

Cellular structures are central to the design of lightweight yet strong materials for engineering development. However, the material properties of cellular foams made of specific elements are placed in a narrow range in their density and corresponding mechanical properties. Here, this study presents an innovative design of creating closed-cellular structured (CCS) foams with a wide range of physical controllability. The CCS foams are prepared by assembly of solid bubbles consisting of reduced graphene oxide (rGO) and silica nanoparticles. By varying their compositional ratio, the resulting CCS foams exhibit completely discerned structural morphologies: Rhombic dodecahedral (RDH) internal cells for higher rGO content, whereas a fused face centered cubic (FCC)-like internal cells for a higher content of silica. As such, these tunable CCS foams manifest an extended relationship in density and resulting mechanical properties, spanning from a density of 2.3 mg/cm3 and corresponding Young's modulus of 0.102 MPa (for RDH) to 444.27 mg/cm3 and 180.3 MPa (for fused-FCC). Moreover, silica-containing CCS can exhibit a thermal insulation property with a greatly reduced thermal conductivity (κ) of 48 mW/m·K. therefore, this approach of creating the structurally tunable CCS foams would offer a concrete toolkit for designing high-performance cellular structures with on-demand physical/mechanical properties

The importance of high‐performance thermal insulation materials is rapidly emerging due to energy conservation and the management of temperature‐sensitive device perspectives. Recent thermal insulation materials including complex structures have been developed either by reducing the structural connectivity to mitigate thermal transport through solid conduction or forming directionally aligned confined inner pores to suppress the internal gas convection. In this study, to create a highly efficient thermal insulating material that suppresses thermal transport in all directions, graphene‐based anisotropic closed‐cellular structures (CCS) are devised with a highly ordered assembly of hollow compartments with extremely thin walls (≈50 nm). This uniquely designed CCS made from microfluidically synthesized graphene solid bubbles exhibited a remarkably low thermal conductivity of 5.75 mW m −1 K −1 thanks to effective suppression of both solid conduction and gas conduction/convection. Therefore, the proposed strategy in this work offers a novel toolkit for implementing next‐generation high‐performance insulation materials.

We present a microfluidic approach that utilizes temperature-responsive and biocompatible palm oil as the shell material in microcapsules to simultaneously achieve hermetic sealing as well as on-demand temperature-triggered release of the encapsulated actives. Unlike common paraffin waxes (e.g., eicosane), microcapsule shells comprising palm oil do not form pores or cracks during freezing and provide a hermetic seal, a nearly perfect seal that separates the core containing the actives from the surrounding environment over a prolonged period of time. This allows effective isolation and protection of complex cargoes such as small molecules with high diffusivity, strong acids, and cosmetic actives including niacinamide. Moreover, the palm oil shell melts above the defined melting temperature, allowing the on-demand release of the encapsulated actives. Furthermore, palm oil is biocompatible, is edible, and leaves a minimal footprint when used in personal care and cosmetic products, offering new perspectives in the design of microcapsules for cosmetic applications.

Ultrafine grained (UFG) metals processed by the severe plastic deformation technique have an unusual microstructure of `high energy/non-equilibrium' state. It has been shown that fatigue cracks in UFG metals under strain-controlled low-cycle fatigue loading are initiated from shear bands that are the area of severe cyclic strain localization. On the other hand, current research lacks the required data to verify the crack initiation mechanism of UFG metals under high-cycle fatigue (HCF) loading. In this study, HCF tests under stress control were conducted on UFG copper to examine the behavior of crack initiation. The morphological change close to the damage traces, which evolved to a fatigue crack during ensuing cyclic stressing, was monitored. Inner fatigue damage was also analyzed by using a focused ion beam technique. Four typical sites of surface-crack initiation were commonly observed: i) persistent slip bands inside coarse dynamically recovered/recrystallized grains, ii) line-shaped damage traces in UFG structure, iii) near coarse grain boundaries, and iv) protruded surface inside the near-by oriented grains. The initiation mechanism of HCF crack in UFG copper was discussed in light of the morphological change in surface damage during cyclic stressing and the formation of embryonic cracks in high energy state microstructure.

The onset of ductile fracture can be described by a simple damage parameter, which accounts for the accumulation of damage under arbitrary deformation. The damage parameter is usually given as integral form of strain over loading history which also has been described as a function of stress state. While the evolution of strain field can be experimentally determined using digital image correlation, experimental measurement of the multiaxial stress state is still a challenging task. Therefore, various uncoupled fracture criteria rely on stress states calculated from phenomenological plasticity model. As a result, the number of mechanical tests required to calibrate the fracture criterion may significantly increase when an anisotropic constitutive model is used. We propose an alternative approach on the basis of a mean field crystal plasticity (VPSC) model, which accounts for the microstructural features such as slip system, crystallographic texture and its evolution. While stress fields can be obtained from the use of full-field crystal plasticity framework, the proposed method utilizes the mean field crystal plasticity framework and repeat the stress estimation on various spatially resolved locations to which DIC technique provides strain history. The repeated VPSC calculations at various locations efficiently provide the map of stress evolution. The resulting map of spatially resolved stress response is further validated by comparing with the bulge stress strain curves.

Discrepancies remain about nature of dislocation-interstitial interaction governing yielding discontinuity in fcc materials. Here, we show that outward diffusion of nitrogen from stacking fault (SF) into matrix causes strain redistribution, leading to lowering stacking fault energy. Local fluctuation of nitrogen promotes fault growth coupled with nitrogen-enriched zone, contributing to enhanced plasticity.

Platycodon grandiflorum root is a traditional medicine and food material rich in triterpenoid saponins. Its major constituent, platycodin D (PD), is known to have various pharmacological properties, but processing methods may influence the PD content. In this study, a fully validated HPLC–ELSD method was developed for the quantification of PD in various states of 73 P. grandiflorum root samples from East Asia, and it exhibited a marked variation of the content. Furthermore, the effects of processing procedures such as peeling and drying temperature on the PD content were investigated using UPLC–ELSD analysis, and as a result, a significant influence of processing methods such as peeling and heating of samples on the content was confirmed. Specifically, unpeeled samples that were dried at 40 °C showed the greatest PD content. The obtained results could facilitate the reliable standardization of P. grandiflorum for precise authentication and efficacious applications.

For low-cycle fatigued, ultrafine grained copper, processed by equal channel angular pressing, a unique crack growth direction, either inclined at 45 degrees or perpendicular to the loading direction, was observed around the circumference of round bar specimens. In addition, the perpendicular cracks showed a 45 degrees deflected crack face toward the center of the specimens. To clarify the growth behavior of such inclined and deflected cracks, the role of the deformation mode at the crack-tip areas was discussed in terms of the surface damage caused by cyclic stressing and the mixed-mode deformation at the crack tips. The preexistent shear-bands/shear-cracks around the crack tips and the in-plane shear-mode deformation at the crack tips assisted the formation of shallow inclined- and deep deflected-cracks. To quantitatively estimate the severity of mechanical damage at the crack tips, the comparative stress intensity factor range under combined mode I, II and III conditions were calculated. The crack growth rate along the growth direction at the surface and bottom for inclined and deflected surface-cracks was discussed in terms of the comparative stress intensity factor range. (c) 2017 Elsevier Ltd. All rights reserved.

A new cytoprotective compound, 1-[(4S)-3,4-dihydro-4-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-yl]-ethanone (1) was isolated from the flower buds of Tussilago farfara L. (Compositae), together with eight known compounds, 3,4-dicaffeoyl isoquinic acid (2), trans-cinnamic acid (3), 4-hydroxyacetophenone (4), 4,5-dicaffeoylquinic acid methyl ester (5), 3,5-dicaffeoylquinic acid methyl ester (6), 4-hydroxybenzoic acid (7), isoquercetrin (8), and ligucyperonol (9). Compounds 2–4 were found in this plant for the first time. The isolates 1–9, were tested for their cytoprotective activities against glucose oxidase-induced oxidative stress in mouse fibroblast NIH3T3 cells and human keratinocyte HaCaT cells. Among them, 1 and 3 showed significant cytoprotective activities as determined by MTT assay and lactate dehydrogenase leakage, indicating their possibility as the potent cytoprotective agents. The structure of 1 was determined by spectroscopic data analysis including 1D- and 2D-NMR experiments, and its absolute configuration was elucidated by a circular dichroism.

As digital evidence has a highly influential role in proving the innocence of suspects, methods for integrity verification of such digital evidence have become essential in the digital forensic field. Most surveillance camera systems are not equipped with proper built-in integrity protection functions. Because digital forgery techniques are becoming increasingly sophisticated, manually determining whether digital content has been falsified is becoming extremely difficult for investigators. Hence, systematic approaches to forensic integrity verification are essential for ascertaining truth or falsehood. We propose an integrity determination method that utilizes the structure of the video content in a Video Event Data Recorder (VEDR). The proposed method identifies the difference in frame index fields between a forged file and an original file. Experiments conducted using real VEDRs in the market and video files forged by a video editing tool demonstrate that the proposed integrity verification scheme can detect broken integrity in video content.

The formation mechanism of inclined fatigue-cracks in ultrafine-grained Cu processed by equal channel angular pressing was studied by using a partially notched specimen in which a fatal natural crack was introduced, to a specific site of the smooth surface was feasible regardless of microstructural inhomogeneity caused by the processing. The crack growth direction depended on the location along the circumferential direction of the round bar specimen and on the applied stress amplitudes. The role of the microstructure and deformation mode at the crack-tip areas on the formation behavior of fatal cracks is discussed in terms of the microstructural evolution caused by cyclic stressing and the mixed-mode stress intensity factor. The in-plane shear mode deformation at the crack tip assisted the formation of the inclined crack paths and the unique crack face profile.

Domain Name System (DNS) traffic has become a rich source of information from a security perspective. However, the volume of DNS traffic has been skyrocketing, such that security analyzers experience difficulties in collecting, retrieving, and analyzing the DNS traffic in response to modern Internet threats. More precisely, much of the research relating to DNS has been negatively affected by the dramatic increase in the number of queries and domains. This phenomenon has necessitated a scalable approach, which is not dependent on the volume of DNS traffic. In this paper, we introduce a fast and scalable approach, called PsyBoG, for detecting malicious behavior within large volumes of DNS traffic. PsyBoG leverages a signal processing technique, power spectral density (PSD) analysis, to discover the major frequencies resulting from the periodic DNS queries of botnets. The PSD analysis allows us to detect sophisticated botnets regardless of their evasive techniques, sporadic behavior, and even normal users’ traffic. Furthermore, our method allows us to deal with large-scale DNS data by only utilizing the timing information of query generation regardless of the number of queries and domains. Finally, PsyBoG discovers groups of hosts which show similar patterns of malicious behavior. PsyBoG was evaluated by conducting experiments with two different data sets, namely DNS traces generated by real malware in controlled environments and a large number of real-world DNS traces collected from a recursive DNS server, an authoritative DNS server, and Top-Level Domain (TLD) servers. We utilized the malware traces as the ground truth, and, as a result, PsyBoG performed with a detection accuracy of 95%. By using a large number of DNS traces, we were able to demonstrate the scalability and effectiveness of PsyBoG in terms of practical usage. Finally, PsyBoG detected 23 unknown and 26 known botnet groups with 0.1% false positives.

Real size cylindrical thermal barrier coating (TBC) models, subjecting to symmetric temperature distribution to the radial direction, were taken into consideration in order to evaluate thermoelastic behaviors such as temperature distribution, displacement, and thermal stresses. Heat flux at each layer interface is adjusted to display temperature distribution profiles and the governing differential equations were derived based on thermoelastic theories. The variation of the ratio between the top coat and the substrate yields deep influence on the thermoelastic characteristics of the cylindrical TBC models. The temperature distribution profiles corresponded closely and more sensitive to the change of k of the top coat than the ratio of k2/k1 value. The thermoelastic characteristics in the cylinder react sensitively to the variation of three representative parameters. The 944 Jaegwi Go et al. ratios of mechanical and thermal properties between the top and bond coats, and between the top coat and substrate are crucial factors to be considered in controlling the thermoelastic behaviors of the TBCs, which can be estimated though mathematical approaches.

A vertical continuous casting model is considered to analysis the temperature distribution profiles during the casting process. Heat flux is applied at the interface between the liquid layer and the solid layer to overcome the deficient of insufficiency boundary conditions. By combining the general solution of time dependent heat transfer partial differential equation and heat flux at the interface generate linear systems, and linear systems determine the temperature distribution profiles at each layer. The width of liquid layer and enough time interval are important factors in controlling the casting process and yield profound influence on the mechanisms.

The sharp increase in smartphone malware has become one of the most serious security problems. Since the Android platform has taken the dominant position in smartphone popularity, the number of Android malware has grown correspondingly and represents critical threat to the smartphone users. This rise in malware is primarily attributable to the occurrence of variants of existing malware. A set of variants stem from one malware can be considered as one malware family, and malware families cover more than half of the Android malware population. A conventional technique for defeating malware is the use of signature matching which is efficient from a time perspective but not very practical because of its lack of robustness against the malware variants. As a counter approach for handling the issue of variants behavior analysis techniques have been proposed but require extensive time and resources. In this paper, we propose an Android malware detection mechanism that uses automated family signature extraction and family signature matching. Key concept of the mechanism is to extract a set of family representative binary patterns from evaluated family members as a signature and to classify each set of variants into a malware family via an estimation of similarity to the signatures. The proposed family signature and detection mechanism offers more flexible variant detection than does the legacy signature matching, which is strictly dependent on the presence of a specific string. Furthermore, compared with the previous behavior analysis techniques considering family detection, the proposed family signature has higher detection accuracy without the need for the significant overhead of data and control flow analysis. Using the proposed signature, we can detect new variants of known malware efficiently and accurately by static matching. We evaluated our mechanism with 5846 real world Android malware samples belonging to 48 families collected in April 2014 at an anti-virus company; experimental results showed that; our mechanism achieved greater than 97% accuracy in detection of variants. We also demonstrated that the mechanism has a linear time complexity with the number of target applications.