Thermodynamics of Dissociation and Micellization of Sodium Surfactant Solutions in Formamide

Electrical conductivity and surface tension measurement of sodium surfactants, such as sodium caprylate, sodium laurate, sodium palmitate and sodium stearate, in formamide has been determined at different temperatures. The methods show that micelles are formed in formamide solution. Critical micelle concentration (CMC) has been determined for each of the sodium surfactants. The result show that these surfactants behave as a weak electrolyte in dilute solution of formamide below the critical micellar concentration, and the conductance result can be explained on the basis of Ostwald’s formula and Debye–Huckle’s theory of weak electrolytes. The dissociation constant and thermodynamic parameters for dissociation and micellization processes of these surfactants are also evaluated. The micellization process has been found to be predominant over the dissociation process. Keywords: Critical Micelle Concentration (CMC), Micellization, Conductivity, Dissociation, Thermodynamics, Surface Tensio

Micellization Behavior of Ionic Surfactants in Presence of Butanol Isomers in Non-aqueous Solutions

Electrical conductivity and surface tension measurements of various surfactants, such as sodium caprylate, sodium laurate, sodium palmitate and sodium stearate micellar solution,  containing  1-butanol  (1-BuOH),  2-butanol  (2-BuOH)  and tertiary butanol (t-BuOH) in n,n-dimethyl acetamide have been determined at various temperatures. Both methods show that micelles are formed in n,n-dimethyl acetamide  (DMA) solution in the presence of butanol isomers. Critical micelle concentration (cmc) has been determined for each of the surfactants. Critical micelle concentrations have also been measured as a function of temperatures and concentration of butanol isomers added. It is suggested that the addition of alcohol leads to an increase in n,n-dimethyl acetamide penetration into the micellar interface that depends on the alkyl chain configuration for three isomeric alcohols. Thermodynamic parameters of micellization, enthalpy  (ÄH0m,  entropy  (ÄS0m),  and free energy  (ÄG0m)  were determined from the temperature  dependence of  CMC.  The solvent composition dependence of these thermodynamic parameters is determined in terms of the effect of additives on the micellization of ionic surfactants. It is observed that both ÄH0m and ÄS0m bear out not only the observed order of decrease in cmc but also account reasonably the effects produced by differences in alkyl chain configuration for these isomeric alcohols. In all cases ÄG0m < 0, and remained practically constant over the entire solvent composition range studied.  It is suggested that due to different structural consequences of intermolecular interactions,  both enthalpy and entropy must differ in a  mutually compensating manner so that G0m is not significantly affected

The Mn site in Mn-doped Ga-As nanowires: an EXAFS study

We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched Mn-As coordination we have found the presence of Mn in a Mn-Au intermetallic compound.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Semiconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version is available online at doi:10.1088/0268-1242/27/8/08500

Acute phase reactants and lipid profile in acute chest pain presentations: a multimarker approach

Background: Cardiovascular diseases cause more deaths and disability and incur greater economic cost than any other illness in the world. Our objective is to study the biological activity and evaluate the diagnostic and prognostic values of acute phase reactants, high sensitivity C-reactive protein (hsCRP) and ferritin in association with traditional lipid profile, in screening subjects who developed chest pain due to cardiac event as indicated by a positive cardiac troponin I (cTnI) test.Methods: In this hospital-based prospective study, a total of 150 cases (n=150), presented consecutively to the emergency department with symptoms of cardiac ischemia and tested positive for troponin I (enzyme-linked flourescent assay), were compared with an equal number of age and gender matched healthy controls (n=150) for hsCRP (immunoturbidimetric assay), ferritin (immunoturbidimetric assay) and lipid profile (enzymatic colorimetric assay).Results: Median serum hsCRP levels were 2.12 mg/L)±1.79 mg/L) than controls (2.82±significantly elevated in cases (3.57 (p0.05) different between the two groups.Conclusions: hsCRP and ferritin are independent novel predictors for cardiovascular risks and events. Lipid profile demonstrates low specificity in such cases.

Indigenous uses of economically important flora of Margallah Hills National Park, Islamabad, Pakistan

Informal interviews provided data about 245 useful plants of 77 families of 55 trees, 54 shrubs, 105 herbs, 15 climber, 10 grasses and 6 crops recorded from the Margallah Hills National Park, Islamabad.Two hundred and fifteen local/ vernacular names were noted of total plants. The inhabitants of the park have for a long time been dependent on surrounding plant resources for their food, health care, fodder,fuel wood and other cultural purposes. A list of plant species along with their local name, plant part/s used, popular uses (or troubles treated) are given. The pastoral nomads of the area make use of 159(64.89%) as native medicine, 79 (32.24%) as fodder for their livestock, 47(19.18%) as fuelwood, 33 (13.46%) as food (fruits), 18 (7.34%) as vegetables, 14 (5.71%) as timber, 6 (2.44%) as industrial, 4 (1.63%) as tannin, 3 (1.22%) as gum and 2 (0.81%) as fiber. Medicinal uses of the 126 plant species have also been described. This information will serve as reference for the benefit of pharmacists, researchers, Hakims (herbalist), veterinarians and public at large

Phylogeny of Artemisia L.: Recent developments

In this review, classification and phylogeny of genus Artemisia L. is discussed. Its centers of diversity lie in the temperate and cold temperate regions of the Eurasia, North America and Asia. Artemisia has two basic chromosome numbers, with ploidy levels x=9 and x=8. Chromosome number in diploid is most often 2n=18 or 16. The genus is divided into five large groups Absinthium DC., Artemisia L., Dracunculus Besser, Seriphidium Besser and Tridantatae (Rydb.) McArthur. Its phylogeny was based on the two hypothesized evolutionary trends, loss of fertility in the disc florets and loss of ray florets. Recently its molecular phylogeny based on internally transcribed spacer (ITS), externally transcribed spacer (ETS) regions of the DNA and chloroplast DNA suggested that the genus Artemisia is a monophyletic but it could not resolve the problem of infra-generic classification. This study revealed that there is need to search new genome regions to establish a natural classification based on modern molecular techniques

Blockchain-based DDoS attack mitigation protocol for device-to-device interaction in smart homes

Smart home devices are vulnerable to a variety of attacks. The matter gets more complicated when a number of devices collaborate to launch a colluding attack (e.g. Distributed-Denial-of-Service (DDoS)) in a network (e.g., Smart home). To handle these attacks, most studies have hitherto proposed authentication protocols that cannot necessarily be implemented in devices, especially during Device-to-Device (D2D) interactions. Tapping into the potential of Ethereum blockchain and smart contracts, this work proposes a lightweight authentication mechanism that enables safe D2D interactions in a smart home. The Ethereum blockchain enables the implementation of a decentralized prototype as well as a peer-to-peer distributed ledger system. The work also uses a single server queuing system model and the authentication mechanism to curtail DDoS attacks by controlling the number of service requests in the system. The simulation was conducted twenty times, each with varying number of devices chosen at random (ranging from 1 to 30). Each requester device sends an arbitrary request with a unique resource requirement at a time. This is done to measure the system’s consistency across a variety of device capabilities. The experimental results show that the proposed protocol not only prevents colluding attacks, but also outperforms the benchmark protocols in terms of computational cost, message processing, and response time