Computation of generalized inverses using Php/MySql environment

The main aim of this paper is to develop a client/server-based model for computing the weighted Moore-Penrose inverse using the partitioning method as well as for storage of generated results. The web application is developed in the PHP/MySQL environment. The source code is open and free for testing by using a web browser. Influence of different matrix representations and storage systems on the computational time is investigated. The CPU time for searching the previously stored pseudo-inverses is compared with the CPU time spent for new computation of the same inverses.Comment: International Journal of Computer Mathematics, Volume 88, Issue 11, 201

Towards sustainable polymeric nano-carriers and surfactants: facile low temperature enzymatic synthesis of bio-based amphiphilic copolymers in scCO2

We demonstrate that useful bio-based amphiphilic polymers can be produced enzymatically at a mild temperature, in a solvent-free system and using renewably sourced monomers, by exploiting the unique properties of supercritical CO2 (scCO2). We present the use of a novel near-ambient temperature approach to prepare renewable amphiphilic ABA copolymers in scCO2. Bio-based commercially available monomers have been polymerised to prepare chains with targeted molecular weight. The amphiphilic materials were prepared by end-capping the synthesised polymers with methoxy poly(ethylene glycol) (MPEG) chains in a one-pot high pressure reaction utilising Candida Antarctica Lipase B (CaLB) as a catalyst at a temperature as low as 35 °C. The block copolymers are characterised by 1H-NMR, GPC and DSC in order to carefully assess their structural and thermal properties. These polymers form self-assembled aggregates in aqueous environment and these nanostructures are studied through DLS, TEM and UV-Vis. Highly hydrophobic Coumarin-6 was used as a model to prove dispersion in water of lipophilic molecules. Maximum bubble pressure tests demonstrate the reduction in surface tension of these polymers and comparisons are made directly to commercial polymeric non-ionic surfactants

Weighted Moore–Penrose generalized matrix inverse: MySQL vs. Cassandra database storage system

© 2016, Indian Academy of Sciences. The research in this paper refers to two areas: programming and data storage (data base) for computing the weighted Moore–Penrose inverse. The main aim of this paper analysis of the execution speed of computing using PHP programming language and data store. The research shows that the speed of execution gives considerable difference between the Procedural programming and Object Oriented PHP language, on the middle layer in the three tier of the web architecture. Also, the research concerning the comparison of relation database system, MySQL and NoSQL, key value store system, ApacheCassandra, on the database layer. The CPU times are compared and discussed

Ispitivanje uticaja koncentracije suspenzije na širinu pHmax – pHmin opsega tokom određivanja rastvorljivosti

The solubility profile of a drug typically consists of two independent curves that intersect at a specific point called pHmax. At pHmax, both salt and base coexist as solid phases. While two solids coexist, pH and solubility in the heterogeneous system remain constant (according to the Gibbs Phase Rule). Recent studies, however, have shown that pH and solubility might change during the salt-to-free-base transformation. This pH range, containing two solids, is termed the pHmax – pHmin range. pHmax refers to the pH value at the maximum solubility of a eutectic mixture, whereas pHmin represents the pH value at the minimum solubility of the eutectic mixture. The objective of this study was to investigate the influence of suspension concentration (the ratio of drug mass to suspension volume) on the pHmax – pHmin range during solubility determination using the pH-Ramp shake-flask method. Nortriptyline hydrochloride (Nor, monoprotic base) and atorvastatin calcium (At, monoprotic acid) were employed as model compounds. Results indicate that the pHmax – pHmin range increases as suspension concentration rises (for 20.10 mg NorHCl/mL: pHmax=3.55, ΔpH=0; for 59.82 mg NorHCl/mL: pHmax – pHmin= 3.56 – 4.52, ΔpH=0.96). Understanding the details of the pHmax – pHmin range could significantly impact product formulation optimization in drug researchCilj ovog rada bio je ispitivanje uticaja koncentracije suspenzije na širinu pHmax – pHmin opsega tokom određivanja rastvorljivosti pH-Ramp shake-flask metodom. Kao model jedinjenja izabrani su nortriptilin-hidrohlorid i atorvastatin-kalcijum. Rezultati su pokazali da sa porastom koncentracije suspenzije dolazi do širenja opsega pHmax – pHmin, a ovakva proučavanja mogu značajno doprineti optimizaciji formulacije u procesu dizajna i razvoja lekova

Optimization of preparation conditions of poly(ε-caprolactone) microspheres for controlled release of carbamazepine

Poly (ε-caprolactone), PCL, is an aliphatic polyester suitable for controlled drug release due to its biodegradability, biocompatibility, non-toxicity and high permeability to many therapeutic drugs. This study investigates the effect of the preparation parameters on the size and the morphology of the PCL microspheres and on the release profile of carbamazepine from these microspheres. The PCL microspheres were prepared using oil-in-water (o/w) emulsion solvent evaporation method with the poly(vinyl alcohol), PVA, as the emulsion stabilizer. The influence of the stirring rate applied during the emulsion formation, the homogenization time and the emulsifier concentration on diameter and size distribution of the microspheres was analyzed by scanning electron microscope (SEM). The initial emulsion was formed applying high stirring rates of 10000, 18000 and 23000 rpm, for homogenization times: 5, 10 and 15 min. The diameter was strongly influenced by the stirring rate, and the average particle size decreased from 9.2 to 2.8 µm with the increase of the stirring rate. Increasing the amount of PVA in the water phase from 0.2 to 1 mass% improved stabilization of the oil droplets and led to a slight decrease of the average particle diameter. Drug-loaded microspheres were prepared by the same technique using different amounts of carbamazepine (10 and 15 mass%), under given conditions (1 mass% PVA, stirring rate of 18000 rpm for a period of 5 min of emulsion formation). Additionally, microspheres were prepared by applying low stirring rate of 1000 rpm with 10 and 15 mass% of the drug. The SEM analysis showed that microspheres created with 18000 rpm stirring rate, had average diameters of 3-4 µm, and the microspheres prepared with 1000 rpm stirring rate were larger than 100 µm. It was also observed that, in the case of the large microspheres, carbamazepine was deposited on their surfaces, while the small microspheres had smooth surfaces without observable drug crystals. The encapsulation efficiency and the release behavior of the carbamazepine were examined using high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV). The drug encapsulation efficiencies were in the range from 69 to 81%, and were increasing with the increase of the amount of carbamazepine in both series. In vitro release experiments were carried out in the phosphate buffer solution (pH 7) at 37ºC. The release rate was influenced by the microspheres size and morphology. The larger microspheres released more carbamazepine (85-95%) compared to the small ones (50-65%) for the same period. This behavior was attributed to the different drug distribution in the PCL matrix. Different mathematical models were used to describe drug release kinetics. It was concluded that the mechanism of the carbamazepine release from the microspheres was diffusion-controlled, independent on the type of microspheres. The kinetic parameters showed that the release of carbamazepine was slower from the smaller microspheres, probably as a result of more even distribution of the drug in the polymer matrix

Leber hereditary optic neuropathy in the population of Serbia

Background: Leber hereditary optic neuropathy (LHON) is the most common mitochondrial disorder. However, few countries have published their population-based findings related to this multisystemic disease. The aim: In order to get a better insight into the epidemiological and clinical picture of this maternally inherited disorder, we performed the first population-based clinical and molecular-genetic study of LHON in the Serbian population. Methods: Prospective study included patients who were diagnosed with LHON after detailed medical examination and molecular-genetic confirmation. Results: We identified 41 individuals from 12 genealogically unrelated families, carrying one of the three "primary" mitochondrial (mt) DNA point mutations associated with LHON. Fourteen of them were clinically affected, giving a minimum point prevalence of 1.9 per 1 000 000. The minimum point prevalence for mtDNA LHON mutations was 5.2 per 1 000 000. Male to female ratio was 6:1. Only one affected patient harboured mutant mtDNA in heteroplasmic condition. All patients were presented with common clinical findings. Conclusion: We observed significantly lower prevalence and higher gender ratio than expected. However, frequencies of primary mutations, incidence of heteroplasmy and clinical findings are in accordance with other studies in Caucasoid populations. Our results might be a consequence of poor recognition and misdiagnosis due to lack of diagnostic possibilities of the entity in different region of our country or less likely be in part due to specific haplotype background of Serbian population which should be further investigated