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With the advancement of solid-state devices for lighting, illumination is on the verge of being completely restructured. This revolution comes with numerous advantages and viable opportunities that can transform the world of wireless communications for the better. Solid-state LEDs are rapidly replacing the contemporary incandescent and fluorescent lamps. In addition to their high energy efficiency, LEDs are desirable for their low heat generation, long lifespan, and their capability to switch on and off at an extremely high rate. The ability of switching between different levels of luminous intensity at such a rate has enabled the inception of a new communication technology referred to as visible light communication (VLC). With this technology, the LED lamps are additionally being used for data transmission. This paper provides a tutorial and a survey of VLC in terms of the design, development, and evaluation techniques as well as current challenges and their envisioned solutions. The focus of this paper is mainly directed towards an indoor setup. An overview of VLC, theory of illumination, system receivers, system architecture, and ongoing developments are provided. We further provide some baseline simulation results to give a technical background on the performance of VLC systems. Moreover, we provide the potential of incorporating VLC techniques in the current and upcoming technologies such as fifth-generation (5G), beyond fifth-generation (B5G) wireless communication trends including sixth-generation (6G), and intelligent reflective surfaces (IRSs) among others.

The UAV is emerging as one of the greatest technology developments for rapid network coverage provisioning at affordable cost. The aim of this paper is to outsource network coverage of a specific area according to a desired quality of service requirement and to enable various entities in the network to have intelligence to make autonomous decisions using blockchain and auction mechanisms. In this regard, by considering a multiple-UAV network where each UAV is associated to its own controlling operator, this paper addresses two major challenges: the selection of the UAV for the desired quality of network coverage and the development of a distributed and autonomous real-time monitoring framework for the enforcement of service level agreement (SLA). For a suitable UAV selection, we employ a reputation-based auction mechanism to model the interaction between the business agent who is interested in outsourcing the network coverage and the UAV operators serving in closeby areas. In addition, theoretical analysis is performed to show that the proposed auction mechanism attains a dominant strategy equilibrium. For the SLA enforcement and trust model, we propose a permissioned blockchain architecture considering Support Vector Machine (SVM) for real-time autonomous and distributed monitoring of UAV service. In particular, smart contract features of the blockchain are invoked for enforcing the SLA terms of payment and penalty, and for quantifying the UAV service reputation. Simulation results confirm the accuracy of theoretical analysis and efficacy of the proposed model.

Physical layer security (PLS) is considered as a promising technique to prevent information eavesdropping in wireless systems. In this context, cooperative relaying has emerged as a robust solution for achieving PLS due to multipath diversity and relatively lower transmission power. However, relays or the relay operators in the practical environment are unwilling for service provisioning unless they are incentivized for their cost of services. Thus, it is required to jointly consider network economics and relay cooperation to improve system efficiency. In this paper, we consider the problem of joint network economics and PLS using cooperative relaying and jamming. Based on the double auction theory, we model the interaction between transmitters seeking for a particular level of secure transmission of information and relay operators for suitable relay and jammer assignment, in a multiple source-destination networks. In addition, theoretical analyses are presented to justify that the proposed auction mechanism satisfies the desirable economic properties of individual rationality, budget balance, and truthfulness. As the participants in the traditional centralized auction framework may take selfish actions or collude with each other, we propose a decentralized and trustless auction framework based on blockchain technology. In particular, we exploit the smart contract feature of blockchain to construct a completely autonomous framework, where all the participants are financially enforced by smart contract terms. The security properties of the proposed framework are also discussed.

The objective of the study was to investigate the suitability of the Plantago ovata (PO) husk as a pharmaceutical excipient. Various phytoconstituents of the husk were determined according to the standard test procedures. The Plantago ovata husk was evaluated for various pharmaceutical parameters related to flow, swelling index, and compressibility index. Orodispersible tablets (ODTs) were prepared, containing different concentrations (2.5, 3, 5, 7.5, 10, and 15% w / w ) of the Plantago ovata husk. Before compression, all the formulations were evaluated for their flow. Compressed ODTs were evaluated for physical characteristics (physical appearance, weight and weight variation, thickness, and moisture content), mechanical strength (crushing strength, specific crushing strength, tensile strength, and friability), disintegration behavior (disintegration time and oral disintegration time), drug content, and in vitro drug release. Phytochemical evaluation of the Plantago ovata husk confirmed the presence of various phytoconstituents like alkaloids, tannins, glycosides, saponins, flavonoids, and phenols. SEM photograph of the Plantago ovata husk showed that it has a fibrous structure, with a porous and rough surface. The Plantago ovata husk had a high swelling index (380%) which decreased by pulverization (310%). Precompression evaluation of the powder blend for all the formulations of ODTs showed good flow properties, indicating that the Plantago ovata husk improved the rheological characteristics of the powder blend. Compressed ODTs had good mechanical strength, and their friability was within the official limits ( w / w of the Plantago ovata husk. It is concluded that the Plantago ovata husk can be used as a disintegrant in the formulation of ODTs.

Inspired by its success in financial sectors, the blockchain technique is emerging as an enabling technology for secure distributed control and management of wireless networks. In order to fully benefit from this distributed ledger technology, its limitations, cost, complexity and empowerment also have to be critically appraised. Depending on the specific context of the problem to be solved, these limitations have been handled to some extent through a clear dichotomy in the blockchain architectures, namely by conceiving both permissioned and permissionless blockchains. Permissionless blockchain requires massive computing power to achieve consensus, while its permissioned counterpart is energy efficient but would require trusted participants. To combine these benefits by gaining trust at a high energy efficiency, a novel mechanism is proposed for automatically learning the trust level of users in a public blockchain network and granting them access to a private blockchain network. In this context, machine learning is a very powerful tool capable of automatically learning the trust level. We have proposed reinforcement learning for bridging the dichotomy of blockchains in terms of striking a trust vs complexity trade-off in an unknown environment. Benefits and limitations of various forms of blockchain techniques are analyzed, followed by their reinforcement-aided evolution. We demonstrate that the proposed reinforcement learning aided blockchain is capable of supporting high-integrity autonomous operation and decision making in wireless networks. The win-win amalgamation of these techniques has been demonstrated for striking a compelling balance between the benefits of permissioned and permissionless blockchain networks through the case-study of the proposed blockchain based unmanned aerial vehicle aided wireless networks.

Liquisolid compact is a novel dosage form in which a liquid medication (liquid drug, drug solution/dispersion in non-volatile solvent/solvent system) is converted to a dry, free flowing powder and compressed. Objective of the study was to elucidate the effect of carrier material on release characteristics of clopidogrel from liquisolid compacts. Different formulations of liquisolid compacts were developed using microcrystalline cellulose, starch maize, polyvinyl pyrollidone and hydroxypropyl methylcellulose as carrier material in three concentrations (40, 30 and 20%, w/w). Liquid vehicle was selected on the basis of solubility of clopidogrel. Colloidal silicondioxide was used as coating material and ratio of carrier to coating material was kept 10. A control formulation comprised of microcrystalline cellulose (diluents), tabletose-80 (diluents), primojel (disintegrant) and magnesium stearate (lubricant) was prepared by direct compression technique and was used for comparison. All the formulations were evaluated at pre and post compression level. Acid solubility profile showed higher solubility in HCl buffer pH2 (296.89±3.49 μg/mL). Mixture of propylene glycol and water (2:1, v/v) was selected as liquid vehicle. Drug content was in the range of 99–101% of the claimed quantity. All the formulations showed better mechanical strength and their friability was within the official limits (

The objective of the study was application of SeDeM-ODT expert system for optimization of process variables for roller compaction and for the preparation of granules with better flow, compressibility, and disintegration behavior. In the present study, granules were prepared at pre-determined (on the basis of factorial design) process variables and characterized using SeDeM-ODT expert system. Compatibility of ribavirin with excipients (microcrystalline cellulose, tablettose-80, cross carmellose sodium, and magnesium stearate) was evaluated by binary mixture approach, using FTIR. According to the SeDeM-ODT expert system, granules were characterized for various parameters related to flow, compressibility and disintegration behavior and Index of Good Compressibility and Buccodispersibility (IGCB) was calculated. The process variables resulting in highest IGCB value were considered as optimum. Ribavirin was found compatible with all the excipients used in the study and characteristics peaks were present in FTIR spectra after subjecting to stress conditions (75% relative humidity at 45 ± 5 °C) for 30 days. Both Ribavirin powder and Ribavirin containing powder blend had poor flow and compressibility while disintegration behavior was good due to higher water solubility. Screw speed of 35 rpm and roller speed at 12 rpm resulted in granules with acceptable characteristics. The IGCB value (5.63) of the granules was highest of all, indicating its better characteristics. SeDeM-ODT expert system presents a more practical picture of the granules and also predicts the mechanical strength and disintegration behavior of the tablets prepared from the granules. By proper optimization of screw and roller speed, efficiency of the process can be improved.

This paper considers a network of source nodes that transmit data packets to a destination node via relay nodes over erasure channels by using random linear network coding. The probability that the destination node will fail to recover the packets of all source nodes has been bounded and approximated in the literature for the case of relay nodes that randomly assign only nonzero values to the coefficients of linear combinations of data packets. The paper argues for the necessity of giving relay nodes the choice to also assign the zero value to coefficients when arithmetic operations are over finite fields of small size, e.g. GF(2). Alternative probability mass functions for the coefficients are considered, and expressions for the decoding failure probability are re-derived.

Drug release from liquisolid compacts is dependent on several variables and changes in experimental parameters, like drug loading and the type and quantity of the carrier material, which affect the dissolution rate, significantly. Therefore, a dissolution method is needed that can discriminate among in vitro release profiles of liquisolid compacts of varying nature. The objective of this study was to develop and validate a discriminatory dissolution testing method for liquisolid compacts of hydrochlorothiazide (HCTZ) to evaluate the effect of formulation and process variables on dissolution rate. Various experimental conditions were optimized, and the method was validated according to USP and ICH guidelines for different parameters like linearity, specificity, accuracy, precision, and stability of solution. Analysis of dissolution samples was carried out by high-performance liquid chromatography (HPLC). The discriminatory nature of the method was confirmed by determining dissolution rates of liquisolid compacts of HCTZ prepared with different load factors. A model-independent approach was applied for comparison of different dissolution profiles. Based on a screening study, USP apparatus I (basket method) was selected. The best in vitro dissolution profile was obtained using purified water containing Tween-80 (0.5% v/v) as the dissolution medium (900 mL), stirred at 75 rpm. Complete dissolution (99.83 ± 1.03%) was achieved within 60 min and dissolution media had no interference with sample analysis. HCTZ exhibited a linear response (r2 = 0.9974) in the selected dissolution medium and showed accurate results (98%–100%) in the concentration rage of 80%–120% of the dose. All validation parameters were found in acceptable range (%RSD > 2), and drug samples prepared in dissolution medium were stable for the specified period. Comparison of dissolution profiles in the official and developed media showed significant differences in f1 and f2 values. The developed dissolution test exhibited higher discriminative capacity in differentiating release profiles of HCTZ and can be applied during formulation development and quality control analysis of liquisolid compacts.

A simple, economical, fast, and sensitive RP-HPLC-UV method has been developed for the simultaneous quantification of Sorafenib and paclitaxel in biological samples and formulations using piroxicam as an internal standard. The experimental conditions were optimized and method was validated according to the standard guidelines. The separation of both the analytes and internal standard was achieved on Discovery HS C18 column (250mm×4.6mm, 5μm) using Acetonitrile and TFA (0.025%) in the ratio of (65:35V/V) as the mobile phase in isocratic mode at a flow rate of 1ml/min, with a wavelength of 245nm and at a column oven temperature of 25°Cin a short run time of 12min. The limits of detection (LLOD) were 5 and 10ng/ml while the limits of quantification (LLOQ) were 10 and 15ng/ml for sorafenib and paclitaxel, respectively. Sorafenib, paclitaxel and piroxicam (IS) were extracted from biological samples by applying acetonitrile as a precipitating and extraction solvent. The method is linear in the range of 15-20,000ng/ml for paclitaxel and 10-5000ng/ml for sorafenib, respectively. The method is sensitive and reliable by considering both of its intra-day and inter-day co-efficient of variance. The method was successfully applied for the quantification of the above mentioned drugs in plasma. The developed method will be applied towards sorafenib and paclitaxel pharmacokinetics studies in animal models.

Drug release from polymeric matrix systems is the rate-limiting step for drug bioavailability and is determined by drug solubility; most drugs show pH-dependent solubility. Polymeric matrices remain in the gastrointestinal tract for a longer period of time and are exposed to environments of varying pH, which can adversely affect drug release. In the present study, the pH-independent drug release of domperidone was achieved by modifying the microenvironmental pH of a swollen polymeric matrix using acidic excipients (citric acid and tartaric acid). Matrices were prepared by a water-based, wet-granulation technique and evaluated for various official and unofficial parameters. In vitro drug release was studied using USP dissolution apparatus and pH 6.80 phosphate buffer as dissolution medium. Release kinetics was evaluated according to various mathematical models. Results show that domperidone release can be effectively modified by inclusion of acidic excipients in the formulations. Acidic excipients modulated microenvironmental pH and avoided the effect of dissolution medium pH on drug release. The resultant formulations are easy to prepare and scale up for commercial manufacturing. Better pH-independent release, following zero-order kinetics, was achieved with tartaric acid.

Opportunistic relaying has the potential to achieve full diversity gain, while random linear network coding (RLNC) can reduce latency and energy consumption. In recent years, there has been a growing interest in the integration of both schemes into wireless networks in order to reap their benefits, while considering security concerns. This paper considers a multi-relay network, where relay nodes employ RLNC to encode confidential data and transmit coded packets to a destination in the presence of an eavesdropper. Four relay selection protocols are studied covering a range of network capabilities, such as the availability of the eavesdropper’s channel state information or the possibility to pair the selected relay with a node that intentionally generates interference. For each case, expressions for the probability that a coded packet will not be recovered by a receiver, which can be either the destination or the eavesdropper, are derived. Based on those expressions, a framework is developed that characterizes the probability of the eavesdropper intercepting a sufficient number of coded packets and partially or fully recovering the confidential data. Simulation results confirm the validity and accuracy of the theoretical framework and unveil the security-reliability trade-offs attained by each RLNC-enabled relay selection protocol.

Polymeric excipients are commonly applied for taste masking of bitter tasting drugs, to get a palatable dosage form, due to wide spectra of characteristics like safety, availability and cost effectiveness. Taste masking changes nature of powder material and affects rheological characteristics, mechanical strength and disintegration behavior which are mandatory for preparation of a pharmaceutical product meeting the official specifications. Extensive experimentation is carried out to get the optimum rheological characteristics; mechanical strength and disintegration behavior are required for a product. In the present study SeDeM-ODT expert system has been applied for prediction of effect of taste masking on various characteristics of powder material at pre-formulation level. Bitter taste of itopride HCl powder was masked by granulation technique using hydroxy propyl methyl cellulose as taste masking polymer. According to SeDeM-ODT expert system, itopride HCl powder was evaluated for 15 basic parameters, before and after taste masking and results were compared. Taste masking was achieved at 1:3 (drug to HPMC ratio by weight) and panel of healthy male volunteers ranked the composition completely taste masked. Comparison of results before and after taste masking showed that taste masking significantly improved mechanical strength and rheological characteristics and decreased disintegration behavior of powder. From the study it is concluded that the effect of taste masking on rheological characteristics, mechanical strength and disintegration behavior can be successfully predicted by SeDeM-ODT expert system at pre-formulation level avoiding extra experimentation and facilitating the process of formulation development.

Liqui-solid technique and solid dispersion formation are two novel approaches for enhancement of dissolution rate of BCS class II drugs. Liqui-solid compact converts a liquid drug or drug solution into a free flowing powder with enhanced dissolution rate. In case of solid dispersion drug is molecularly dispersed in a hydrophilic polymer in solid state. In the present study, Liqui-solid and solid dispersion techniques were applied to enhance the dissolution of the Hydrochlorothiazide. Three formulations of Hydrochlorothiazide were prepared by liqui-solid technique using micro crystalline cellulose as carrier material and colloidal silicon dioxide as coating material. Water, poly ethylene glycol-400 and Tween-60 were used as solvent system. Solid dispersions of Hydrochlorothiazide were prepared by solvent fusion method using PEG-4000 as carrier polymer. Tablets were subjected to evaluation of various physical and chemical characteristics. Dissolution profiles of tablets prepared by the novel techniques were compared with marketed conventional tablets. Model independent techniques including similarity factor, dissimilarity factor and dissolution efficiency were applied for comparison of dissolution profiles. The results obtained indicated that liqui-solid compact formulations were more effective in enhancing the dissolution rate compared with solid dispersion technique. The liqui-solid compacts improved the dissolution rate up to 95% while the solid dispersion increased it to 88%.

This letter considers two groups of source nodes. Each group transmits packets to its own designated destination node over single-hop links and via a cluster of relay nodes shared by both groups. In an effort to boost reliability without sacrificing throughput, a scheme is proposed, whereby packets at the relay nodes are combined using two methods; packets delivered by different groups are mixed using non-orthogonal multiple access principles, while packets originating from the same group are mixed using random linear network coding. An analytical framework that characterizes the performance of the proposed scheme is developed, compared to simulation results, and benchmarked against a counterpart scheme that is based on orthogonal multiple access.

The SeDeM expert system is a pre formulation tool applied for the prediction of the suitability of a material for direct compression. This innovative tool provides an index of good compressibility of the material indicating its aptitude to be compressed by direct compression. In the study the SeDeM expert system has been applied for the prediction of the behavior of the material to be used in the formulation of effervescent tablets by direct compression. Different formulations were developed on the basis of the results of the SeDeM expert system. Various parameters for the material as per the SeDeM expert system were determined according to their official and reported methods. Powder blend for different formulations was evaluated for their rheological properties while tablets were evaluated for various official and unofficial tests.Suitability of the material for direct compression was successfully predicted using the SeDeM expert system. Domperidone was found unsuitable for direct compression. During formulation all excipients responded as they were predicted as per the SeDeM expert system. Tablets produced using the resultant formulations were having sufficient mechanical strength, free of premature effervescence and were capable to be scaled up for commercial manufacturing.

This paper considers a multi-source multi-relay network, in which relay nodes employ a coding scheme based on random linear network coding on source packets and generate coded packets. If a destination node collects enough coded packets, it can recover the packets of all source nodes. The links between source-to-relay nodes and relay-to-destination nodes are modeled as packet erasure channels. Improved bounds on the probability of decoding failure are presented, which are markedly close to simulation results and notably better than previous bounds. Examples demonstrate the tightness and usefulness of the new bounds over the old bounds., 4 pages, 5 figures, accepted for publication in IEEE Communications Letters

Domperidone and Itopride are pro-kinetic agents, regulating the gastric motility and are commonly prescribed as anti emetic drugs. In the present study a simple, rapid and sensitive RP-HPLC/UV method was developed for simultaneous determination of Domperidone and Itopride in pharmaceutical samples and human plasma, using Tenofavir as internal standard. Experimental conditions were optimized and method was validated according to the standard guidelines. Combination of water (pH 3.0) and acetonitrile (65:35 v/v) was used as mobile phase, pumped at the flow rate of 1.5 ml/min. Detector wavelength was set at 210 nm and column oven temperature was 40oC. Unlike conventional liquid-liquid extraction, simple precipitation technique was applied for drug extraction from human plasma using acetonitrile for deprotienation. The method showed adequate separation of both the analytes and best resolution was achieved using Hypersil BDS C8 column (150 mm × 4.6 mm, 5 μm). The method was quite linear in the range of 20-600 ng/ml. Recovery of the method was 92.31% and 89.82% for Domperidone and Itopride, respectively. Retention time of both the analytes and internal standard was below 15 min. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for Domperidone were 5 and 10 ng/ml while for Itopride was 12 and 15 ng/ml, respectively. The developed method was successfully applied for in-vivo analysis of fast dispersible tablets of Domperidone in healthy human volunteer. The proposed method was a part of formulation development study and was efficiently applied for determination of the two drugs in various pharmaceutical products and human plasma.

This letter considers a network comprising a transmitter, which employs random linear network coding to encode a message, a legitimate receiver, which can recover the message if it gathers a sufficient number of linearly independent coded packets, and an eavesdropper. Closed-form expressions for the probability of the eavesdropper intercepting enough coded packets to recover the message are derived. Transmission with and without feedback is studied. Furthermore, an optimization model that minimizes the intercept probability under delay and reliability constraints is presented. Results validate the proposed analysis and quantify the secrecy gain offered by a feedback link from the legitimate receiver., Comment: IEEE Communications Letters, to appear