Hybrid small‐signal model parameter extraction of GaN HEMTs on Si and SiC substrates based on global optimization

This article presents efficient parameters extraction procedure applied to GaN High electron mobility transistor (HEMT) on Si and SiC substrates. The method depends on combined technique of direct and optimization‐based to extract the elements of small‐signal equivalent circuit model (SSECM) for GaN‐on‐Si HEMT. The same model has been also applied to GaN‐on‐SiC substrate to evaluate the effect of the substrates on the model parameters. The quality of extraction was evaluated by means of S‐parameter fitting at pinch‐off and active bias conditions.     

Privacy preserving secure data exchange in mobile P2P cloud healthcare environment

Cloud computing technology offers the possibility of inter-organizational medical data sharing at a larger scale. The different organizations can maintain their own cloud environment while exchanging healthcare data among them in a peer-to-peer(P2P) fashion according to some defined polices. However, there are many security and privacy challenges that hamper the adoption of cloud computing solutions in healthcare domain. Besides, due to the privacy sensitivity of healthcare data, an organization may not wish to disclose its identity to others when exchanging data in the network to avoid different attacks by the intruders. Hence, anonymously authenticated data exchange is essential between the different peer organizations. In this paper we propose an anonymous on-the-fly secure data exchange protocol for such environment based on pairing-based cryptography. Our proposed solution allows cloud peers to dynamically generate temporary identities that are used to produce a session key for each session of data exchange. The proposed protocol is robust against different attacks, such as target-oriented, man-in-the middle, masquerade, and message manipulation attacks.     

Development of natural and synthetic polymer-based semi-interpenetrating polymer network for controlled drug delivery: optimization and in vitro evaluation studies

This research paper describes the development, optimization and in vitro characterization of chemically cross-linked pectin–polyvinyl alcohol-co-poly(2-Acrylamido-2-methylpropane sulfonic acid) semi-interpenetrating polymer network hydrogel [pectin–PVA-co-poly(AMPS) semi-IPN hydrogel] for controlled delivery of model drug tramadol HCl. Response surface methodology based on 3² factorial design was used for optimization and investigating the effect of independent factors: polymer-blend ratio (pectin:PVA = X ₁) and monomer (AMPS = X ₂) concentration on the dependent variables, swelling ratio (q _18th), percent drug release (R _18th, %), time required for 80 % drug release (t _{80 %}, h), drug encapsulation efficiency (DEE, %) and drug loaded contents (DLC, mg/g) in pectin-PVA-co-poly(AMPS) gels prepared by free radical polymerization. The optimized semi-IPN gel (FPP-10) showed controlled in vitro drug release (R _18th) of 56.34 % in 18 h, t _{80 %} of 30 h, and DEE of 23.40 %. These semi-IPN hydrogels were also characterized through SEM, FTIR, sol–gel analysis, swelling studies and drug release characteristics. Therefore, this newly synthesized polymeric network could be a potential polymeric system for controlled drug delivery of tramadol HCl for prolonged drug release.     

Genotype and growing location effects on phytosterols in canola oil

There is little information available about phytosterols in canola (Brassica napa L.) oil and the effects of genotype and growing locations from Virginia and the mid-Atlantic region of the United States, a potential area for the establishment of domestic production to provide edible oil. Our objectives were to characterize the phytosterols, phospholipids, unsaponifiable matter, and FA in oil from Virginia-grown canola. Among 11 canola genotypes grown at two locations during 1995–1996 significant variations existed for oil content and FA profiles, but not for contents of phospholipids, unsaponifiable matter, total phytosterols, campesterol, stigmasterol, and β-sitosterol, Total phytosterol content in the oil of Virginia-grown canola varied from 0.7 to 0.9% with a mean of 0.8%. This concentration compared favorably with oil from Canadian canola, which typically contains 0.5 to 1.1% total phytosterols. The mean contents of brassicasterol, campesterol, stigmasterol, β-sitosterol, Δ⁵-avenasterol, and Δ⁷-stigmatenol as percentages of total phytosterols in Virginia-grown canola were: 9.7, 32.0, 0.6, 49.3, 4.99, and 3.5%, respectively. Growing location did not affect phytosterols in Virginia-grown canola oil but had significant effects on contents of phospholipids, and saturated (myristic, stearic, and arachidic) and unsaturated (palmitoleic, linoleic, linolenic, eicosenoic, and erucic) FA.     

Collective control over sensitive video data using secret sharing

Today digital video is used extensively in many applications. Sometimes a video could be treated as a top secret for an organization, for example military secrets, surveillance footage and corporate product designs, and may need to be shared among a group of people in a secure manner. Traditional data security methods such as encryption techniques are prone to single-point attack, i.e. the secret can be revealed by obtaining the decryption key from any single person. Alternatively, the secret sharing scheme provides collective control over the secrecy of information and is considered information theoretically secure. In this paper, we propose to adopt a secret sharing based approach to provide collective control over a given sensitive video. We present three methods that utilize the spatial and temporal redundancy in videos in different ways. We analyze the security of these methods and compare them for efficiency in terms of computation time and space using extensive experimentation.     

Estimation and optimization based ill-posed inverse restoration using fuzzy logic

Intelligent systems ranging from neural network, evolutionary computations and swarm intelligence to fuzzy systems are extensively exploited by researchers to solve variety of problems. In this paper focus is on deblurring that is considered as an inverse problem. It becomes ill-posed when noise contaminates the blurry image. Hence the problem is very sensitive to small perturbation in data. Conventionally, smoothness constraints are considered as a remedy to cater the sensitivity of the problem. In this paper, fuzzy rule based regularization parameter estimation is proposed with quadratic functional smoothness constraint. For deblurring image in the presence of noise, a constrained least square error function is minimized by the steepest descent algorithm. Visual results and quantitative measurements show the efficiency and robustness of the proposed technique compared to the state of the art and recently proposed methods.     

Soliton solutions for nonlinear Calaogero-Degasperis and potential Kadomtsev-Petviashvili equations

This paper obtains the soliton solution for the Calogero-Degasperis and the potential Kadomtsev-Petviashvili equations. The tanh-coth and the tan-cot methods are used to retrieve the solutions. Finally, the ansatz method is also used to integrate these equations with any arbitrary constant coefficients. Finally, a few numerical simulations are also given.     

Electron beam melting of gamma titanium aluminide and investigating the effect of EBM layer orientation on milling performance

Electron beam melting (EBM) is one of the growing processes of additive manufacturing technology (AMT) to fabricate 3D parts from various difficult-to-process materials such as titanium alloys. A major limitation of the EBM process is the poor surface finish of the produced parts which ultimately demands a subsequent subtractive method (secondary finishing operation) to improve the surface finish for shaping the part to be fit for-end use applications where high surface finish is commonly required. With respect to the EBM layer build direction, the fabricated part has different orientations with varying surface characteristics. Therefore, in order to perform secondary finishing operation (e.g., milling) there are different choices of EBM part orientation to select the direction of tool feed. In this research, 3D parts of titanium alloy (gamma titanium aluminide; γ-TiAl) are additively manufactured through EBM process. The effect of EBM layer/part orientation on the milling performance is further investigated in terms of surface finish improvement and edge chipping evaluation. It has been observed that the EBM layer/part orientation with respect to milling tool feed direction (TFD) plays a vital role in milling performance. Thus, a care must be taken to select the appropriate tool feed direction and layer/part orientation in order to achieve maximum surface finish with minimum edge chipping. The results revealed the vertical milling can be adopted as a secondary finishing operation to be performed on EBM produced parts of γ-TiAl and it allows to significantly improve the poor surface finish generated by EBM (R_a 31 μm). Furthermore, among the available part orientation choices, the part orientation in which the milling tool is fed across the EBM layer build direction is the best orientation resulting into high surface finish (R_a 0.12 μm) with relatively smooth edges (minimum chipping-off).     

Intestinal Radiation Protection and Mitigation by Second-Generation Probiotic Lactobacillus-reuteri Engineered to Deliver Interleukin-22

(1) Background: The systemic administration of therapeutic agents to the intestine including cytokines, such as Interleukin-22 (IL-22), is compromised by damage to the microvasculature 24 hrs after total body irradiation (TBI). At that time, there is significant death of intestinal microvascular endothelial cells and destruction of the lamina propria, which limits drug delivery through the circulation, thus reducing the capacity of therapeutics to stabilize the numbers of Lgr5+ intestinal crypt stem cells and their progeny, and improve survival. By its direct action on intestinal stem cells and their villus regeneration capacity, IL-22 is both an ionizing irradiation protector and mitigator. (2) Methods: To improve delivery of IL-22 to the irradiated intestine, we gavaged Lactobacillus-reuteri as a platform for the second-generation probiotic Lactobacillus-reuteri-Interleukin-22 (LR-IL-22). (3) Results: There was effective radiation mitigation by gavage of LR-IL-22 at 24 h after intestinal irradiation. Multiple biomarkers of radiation damage to the intestine, immune system and bone marrow were improved by LR-IL-22 compared to the gavage of control LR or intraperitoneal injection of IL-22 protein. (4) Conclusions: Oral administration of LR-IL-22 is an effective protector and mitigator of intestinal irradiation damage.