Formulation by design of felodipine loaded liquid and solid self nanoemulsifying drug delivery systems using Box–Behnken design

Objective: To design and develop liquid and solid self-nanoemulsifying drug delivery systems (SNEDDS and S-SNEDDS) of felodipine (FLD) using Box–Behnken design (BBD).

Methods: Solubility study was carried out in various vehicles. Ternary phase diagram was constructed to delineate the boundaries of the nanoemulsion domain. The content of formulation variables, X1 (Acconon E), X2 (Cremophor EL) and X3 (Lutrol E300) were optimized by assessment of 15 formulations (as per BBD) for mean globule sizes in Millipore water (Y1), 0.1?N?HCl (Y2), phosphate buffer (pH 6.4) (Y3); emulsification time (Y4) and T_85% (Y5). The responses (Y1–Y5) were evaluated statistically by analysis of variance and response surface plots to obtain optimum points. The optimized formulations were solidified by adsorption to solid carrier technique using Aerosil 200 (AER).

Results and discussion: Transmission electron microscopy images confirmed the spherical shape of globules with the size range concordant with the globule size analysis by dynamic light scattering technique (<60?nm). The surface morphology of S-SNEDDS (before release) by scanning electron microscopy and atomic force microscopy indicated that SNEDDS are adsorbed uniformly on the surface of AER. The dried residue of S-SNEDDS (after release) revealed the presence of nanometric pores vacated by the previously adsorbed SNEDDS onto AER. Differential scanning calorimetry and X-ray powder diffraction studies illustrated the change of FLD from crystalline to amorphous state.

Conclusion: This study indicates that owing to nanosize, SNEDDS and S-SNEDDS of FLD have potential to enhance its absorption and may serve an efficient oral delivery.     

Airborne Virus Survivability During Long-Term Sampling Using a Non-Viable Andersen Cascade Impactor in an Environmental Chamber

In order to evaluate the survivability of airborne viruses and the sampling performance of an eight-stage non-viable Andersen impactor in typical indoor environments featuring low viral aerosol concentrations, aerosols of a male-specific bacteriophage (MS2), human adenovirus type 1 (HAdV-1), and avian influenza virus (AIV) were sampled size-selectively using the impactor in an environmental chamber. Live virus titer, total virus RNA or DNA concentration, and intensity of a fluorescein tracer were measured to calculate relative virus recovery and virus survival. Viral aerosols were first sampled for 1 and 6 h at 25°C and 50% relative humidity (RH). Virus inactivation and plate overloading were found to be significant in the impactor. Viral aerosols were then sampled at different temperature and humidity levels. MS2 and AIV showed higher survival at lower temperature. Absolute humidity (AH) was found to be a better predictor of virus survival than RH, and the interaction between AH and temperature was not significant. For the tested AH range of 8.8 to 15.2 g/m³, MS2 and HAdV-1 had the highest survival at the lowest AH while AIV had the highest survival at the highest AH. More than 95% of mass collected was for particles smaller than 4.7 m, with the mass median diameter of 1.5 m. In the nebulizer, virus inactivation was not significant at 10 psi (69 kPa) compressed air pressure for up to 6 h of nebulization. Nebulizer analysis also reveals that the use of fluorescein tracer may not always accurately predict the physical loss of virus.

Copyright 2014 American Association for Aerosol Research     

Correlation Between Structure and Ferromagnetism in Cobalt-Doped CdSe Nanorods

The present study deals with the investigation on structural and magnetic properties of pure and Co-doped CdSe nanorods synthesized by solvothermal route. The effects of Co-doping on structural, optical, and magnetic properties of nanorods have been explored using X-ray diffraction (XRD), transmission electron microscopy (TEM), High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), Raman spectroscopy, energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy, electron spin resonance (ESR), and vibrating sample magnetometer (VSM), at room temperature. TEM images show that the synthesized nanorods having length in range of 80–150 nm and diameter of 10–20 nm. No ferromagnetic resonance signal has been observed in ESR spectra, indicating the absence of exchange interactions in pure and doped nanorods. The lattice contraction, increase in band gap, and ferromagnetic behavior have been observed with Co-doping concentration up to 5 %. However, at 10 % Co-doping concentration, reverse trend in above properties has been observed. The study reveals that there is a strong correlation between structural and magnetic properties of Co-doped CdSe nanorods.     

Markov Chain Based Roaming Schemes for Honeypots

The paper proposes a reactive roaming scheme for honeypots. The main aim of a honeypot is to capture the activities of the attacker. If the attacker detects honeypot on a system, its value drops. So, the concept of roaming honeypots is being proposed, to prevent the attacker from detecting the honeypot, which in turn increases the efficiency of honeypot and allows collecting rich data about activities of active attackers. The honeypot is shifted to another system which is most probable to be attacked within the network. The concept of Markov chain analysis is being used to detect the most probable system to be attacked based on the current status of the network. Further, using IP shuffling and services on/off concepts, honeypots roam on the network to the most probable system to be attacked using the threat score. Snort is used to capture data about the number of attacks on each of the nodes of the network and the data collected is then used as an input for Markov chain analysis to identify the most probable system where honeypot can be roamed/moved. The roaming scheme has been implemented for both high interaction honeypots and low interaction honeypots. The high interaction implementation helps in capturing in depth information on a shorter range of IP addresses, whereas the low interaction implementation is efficient in capturing information on a large range of IP addresses. The main advantage of this approach is that it predicts the frequency of attacks on the nodes of a particular network and takes a reactive step by starting the honeypot services on that particular node/system on the network.     

OANTALG: An Orientation Based Ant Colony Algorithm for Mobile Ad Hoc Networks

Mobile ad hoc (MANET) network is collection of nodes, which establish communication among moving nodes in a decentralized way without the use of any fixed infrastructure. Due to unpredictable network topological changes, routing in MANET is a challenging task as it requires a specialized approach to handle these changes due to the random movement of nodes. The routing protocol designed for MANETs should be able to detect and maintain route(s) between the source and the destination nodes in an efficient manner to handle the above defined issues. In this direction, ant colony algorithm is an important category of meta-heuristics techniques, which can provide an efficient solution to many engineering problems. But most of the existing ant colony algorithms explore the search space without initial directions, which lead to the risk of having local optima. To address this issue, in the present paper, we have been motivated and inspired by our previous work (Kumar et al. in Simul Model Pract Theory 19(9):1933–1945, 2011) in which the orientation factor was not considered, and the ant algorithm was applied for service selection in wireless mesh networks (WMNs). But in the current proposal, we have considered the orientation factor and applied the same in MANETs. Hence keeping this point in view, we propose an orientation based ant algorithm (OANTALG) for Routing in MANETs in which the selection of destination nodes and the exchange of ants (agents) between the source and the destination is based upon the orientation factor. During the movement of ants, the pheromone tables and the data structures are created that record the ants trip time between the nodes through which ants make a move. An efficient algorithm for orientation based routing has also been designed in the proposed scheme. The results obtained show that the proposed algorithm performs better than the other state of art algorithms, which are traditional and other ant based algorithms such as AODV, DSR, and HOPNET with respect to various performance metrics such as number of data packets send, throughput, jitter and path length. Simulation results show that OANTALG can send 1.02, 1.44, 1.61 times more number of data packets than AODV, DSR, and HOPNET, respectively. The throughput in OANTALG is 1.79, 30.69, and 48 % more than AODV, DSR and HOPNET, respectively. Packet drop ratio has also been reduced in the proposed OANTALG algorithm as compared to AODV and DSR. Average Jitter is also reduced by 42, 256 and 26.3 % from AODV, DSR and HOPNET, respectively. Average path length of OANTALG is 1.021 and 1.62 times less than AODV and DSR, respectively.     

Privacy Provisioning in Wireless Sensor Networks

Privacy is a necessary component of any security discussion. Privacy and security must be considered separately as well as together. Threads of privacy are visible throughout the procedure of building security solutions for any system. The notions for privacy also play an important role in the technical implications of privacy preservation within any network or its subsystems. Analyzing the mitigations and protections for privacy are considered in privacy notions. The privacy notions being theoretical systems and identified vulnerabilities in the sensor networks not being mapped to such privacy preservation notions necessities the analytical review of privacy provisioning in wireless sensor network (WSN) being formalized within a framework consisting or the vulnerabilities associated with each component of the network and mechanisms of privacy preservation along with the privacy notions. The current research paper provides an analytical review of the privacy provisioning in WSNs with the perspective of development of a proposed framework for privacy notions and quantitative as well as qualitative measures associated with the privacy preservation in sensor network mapped with the various techniques implemented for privacy preservation of different components of the network and the network as a whole. This analytical review has been done on the basis of set of beliefs that an adversary has while launching an attack on the network. Further the existing techniques for privacy preservation of receiver and source node location, location of sink node, traffic analysis prevention and preserving temporal privacy in WSN have been analyses on the basis of adversary’s set of beliefs’ mitigated by them and the notion of privacy implemented by these techniques like k-anonymity, l-diversity or t-closeness. The present effort aims to provide the researchers with an insight of the new concept of belief mitigation for privacy provisioning in WSN.     

On the energy utilization for WSN based on BPSK over the Generalized-K shadowed fading channel

Energy is a scarce resource in the battery-powered nodes of wireless sensor networks (WSNs). In this paper the energy utilization for WSN based on BPSK communications has been investigated over the Generalized-K shadowed fading channel. A comprehensive analysis is reported based on the various important performance metrics like: amount of fading, average bit error probability, outage probability and energy utilized per bit (EUB). Simulation results reveal that composite use of shadowing and fading degrade energy levels to a considerable extent and hence contribute in downsizing the network life-span. We have derived the EUB metric and performed its evaluation with respect to optimal transmit energy levels by varying fading and shadowing severity parameters. We also considered the impact of varying transmit energy levels on the outage probability and hence on transmit and EUB levels. Although, embedding of training sequences and re-transmissions do help in enhancing effective synchronization and improved reliability, but this is done at a cost of higher energy utilization. Under the given set of assumptions, it is observed that an decrease in fading by about 11 %, improves the EUB by about 7 %. With increase in outage probability by about 10 %, EUB improves by about 3 %. An increase in SNR by 6 % improves the EUB levels by about 7 %. The investigations reported in this paper may enable designers to optionally choose suitable parameters to make WSN communications energy-efficient.     

Determination of Elastic Properties of Resected Human Breast Tissue Samples Using Optical Coherence Tomographic Elastography

Abstract: The present study is concerned with the application of optical coherence tomographic (OCT) elastography technique for quantitative assessment of the elastic properties of resected human breast tissue samples subjected to axial compressive loading in vitro. Three classes of breast tissue samples, namely normal, benign (fibroadenoma) and malignant (invasive ductal carcinoma), were considered. A speckle tracking technique based on two‐dimensional cross correlation was employed to track the speckle motion between original (pre‐compressed) and the displaced (post‐compressed) OCT images of the tissue samples for the measurement of displacement and strain maps. The overall data reduction approach for quantitative assessment of elastic properties was validated against the results of gelatin phantoms containing activated charcoal particles as scattering centres. Results are presented in the form of OCT images and displacement and axial strain maps for normal, benign and malignant breast tissue samples. Based on the stress–strain relationship obtained for these three classes, the values of stiffness coefficients were reported in terms of modulus of elasticity. Results of the study reveal significant differences between the two‐dimensional displacement vector maps of normal and cancerous breast tissue samples. The stiffness of benign tissue samples is found to be about two times higher than that of normal tissue samples, whereas for malignant samples, it is about four times higher, thereby signifying appreciable differences in the stiffness of cancerous and normal tissue samples.     

Hydrogen peroxide vapor sensor using metal-phthalocyanine functionalized carbon nanotubes

We have developed a process for preparation of composites by blending and ultrasonification of multi-walled carbon nanotubes with metal-phthalocyanines and have used the same as very selective and sensitive sensor for detection of H₂O₂ vapors. A combination of sensors made from composites of cobalt-phthalocyanine and copper-phthalocyanine with multiwall carbon nanotubes has been found to show opposite conductivities to H₂O₂ vapors while the pair shows similar response to other chemical vapors. This unusual behavior makes this paired sensor as a reliable method to selectively identify the presence of H₂O₂ vapors with response and recovery times of few seconds. Our developed sensors work at room temperature and show resistivity in the range of 10⁴ to 10⁵ Ω cm. They can be employed for detection of H₂O₂ based explosives, to monitor levels of H₂O₂ in industrial units and other applications.