Physicochemical characterization of sodium surfactin for oil and gas industry application

Introduction – Industry operators are becoming more critical of synthetic surfactants for various oil and gas operations. Principal among these concerns is the environmental degradation. As a result, there is increasing interest in the use of biosurfactant, including surfactin, in oil and gas operations. Therefore the need to improve its characteristics, hence performance becomes evident. Characteristics of cultures of surfactin (isolates) were reported. These characteristics could potentially change after synthesis and drying, hence the need for this study. Methodology - The methodology involved characterizing surfactin in aqueous media, and sodium chloride (NaCl) salt solution of 0.1–1.5M concentrations. Properties that influence active site for adsorption (functional group), dispersion (density, foaming), amount of dissolved minerals (pH and conductivity) among others, were analyzed at various surfactin dosages of 0.025 – 1.0%. Results − Results indicated foaming and solubility were excellent in aqueous solution, but significantly affected above 0.5M NaCl concentration. Aqueous surfactin had maximum density of 985.2kg/m3, however increases with increasing NaCl concentration. With pH of 7.1 at 1.0% dosage, aqueous surfactin will pose no corrosion problem to pipelines. Additionally, both surfactin dosage and change in salt concentration exhibited linear relationship effect with pH and conductivity. Infrared analysis confirms cyclic nature of sodium surfactin with lipopeptide chain linked to an aliphatic, hydrocarbon chain. Conclusion − These makes it suitable for use as dispersion agent, viscosity reduction for heavy crude transport, additive for drilling mud preparation, and potential candidate for surface activities, a desirable requirement for oil and gas applications. Keywords: Sodium surfactin, Bacillus subtilis, biosurfactant, physicochemical characteristic

Operative strategy for fistula-in-ano without division of the anal sphincter

We would like to thank Mr ER MacDonald for his contribution in data collection during the early years of the study. The material in this paper was presented as a poster at the annual meeting of the American Society of Colon and Rectal Surgeons held in Vancouver, Canada, May 2011.Peer reviewedPublisher PD

Varicocele Surgery Improves Sperm Count in Infertile Oligospermic Patients and so Improves Fertility; A Study in a Tertiary Care Hospital

The objective of this study was to find out the role of varicocele surgery in oligospermic infertile patients. It was a prospective and descriptive study carried out in Surgical Unit-I, Abbasi Shaheed Hospital and Karachi Medical and Dental College (KMDC), Karachi from April 2004 to March 2014. In this study, all patients of infertility due to low sperm count having bilateral varicocele were included while those patients having azoospermia or patients with unilateral varicocele were excluded. All patients were clinically assessed for bilateral varicocele and confirmed by ultrasonography of scrotum and relevant investigations were done. Patients were prepared for varicocele surgery and ligation of pampiniform plexus done. Semenanalysis were done during follow up and results were analyzed on SPSS version 14. Total fifty seven patients (n=57) were included in which age range was 20 to 30 years in 33.3%, 31 to 40 years in 42.1%, 41 to 50 years in 19.3% and 51 years to onwards in 05.3% patients only. Chronic smoking was found in 68.4% patients while 31.6% were nonsmokers. Normal testes was found in 77.19% while 22.81% had smaller (atrophied) testes. Very low sperm count was in 15.79%, 50.88% had low sperm count and 33.33% had near normal sperm count. All patients were operated for bilateral varicocele and discharged. Follow-up semen analysis showed improvement and semen analysis became normal in 19.3% after six months, 21.05% after nine months and 36.84% after one year of surgery while 22.81% had no improvement even after one year of surgery. Thus, patients with bilateral varicocele having low sperm count showed improvement in sperm count after varicocele surgery and so infertile patients may become fertile after varicocele surgery

Biomass expansion factors of Olea ferruginea (Royle) in sub tropical forests of Pakistan

Wood biomass gives information about total productivity of the forest as well as individual tree. Olea ferruginea (Royle) which is small and evergreen is widely distributed in native sub tropical forests of Pakistan and extensively used as fuelwood domestically. This study was carried out in the sub tropical forests of Pakistan at 33° 38’ north and 73° 00’ east latitude and longitude, respectively, and at an elevation of 917 m. Trees with exploitable diameter were selected randomly from the entire forest.Destructive sampling techniques were used for measuring biomass (kgm-3) in all the tree components. For this purpose, 5 trees were felled and the biomass of each component of the tree including main stem, branches, leaves, twigs and roots were estimated separately using volume, weight and density. The generic data of wood density (kgm-3) was used to determine the biomass (kg). The study showed that average contribution of stem portion of the tree was 49.01% of the total tree biomass, and branches showed 31.17%, leaves 1.98%, twigs 1.05% and roots 16.65% of the total tree biomass. So, it was found that the major part of the total tree biomass was present in the stem portion of O. ferruginea. Totalvolume of the tree was also found to be dependent on the diameter of the tree. Mean volume of the tree was 0.475 ± 0.07 m3. The prepared  biomass expansion factor will be helpful in estimating productivity, carbon stocks and yield of the forest.Key words: Biomass, biomass expansion factor, tree volume, Olea ferruginea

NOMA Enhanced Backscatter Communication for Green IoT Networks

Backscatter communication has recently emerged as a promising technology to enable the passive sensing-based Internet-of-things (IoT) applications. In a backscatter communication network, uplink transmissions of multiple nodes are usually multiplexed in time- or frequency-domain to avoid collisions, yet it is desirable to improve the uplink capacity further. In this paper, we study a wireless-powered backscatter communication system, where the sensors use a hybrid channel access scheme by combining time division multiplexing access (TDMA) with power-domain non-orthogonal multiple access (PD-NOMA) to enhance the system performance in terms of outage probability and throughput. Our analysis shows that the proposed PD-NOMA increases both the spectrum efficiency and the throughput of the system

Design and Characterization of a Flexible Wideband Antenna Using Polydimethylsiloxane Composite Substrate

The design and characterization of a simple, flexible wideband antenna using polydimethylsiloxane (PDMS) composite are presented. Conductive fibers are used to construct the metallic parts on a PDMS composite. To characterize the performance, two identical antennas are designed, one using the PDMS composite while the other on conventional dielectric materials. It was observed that both antennas behave well in terms of the matched bandwidth; however, the radiation towards the broadside direction is reduced when using the PDMS composite as substrate, particularly at higher frequencies. The antenna exhibits a matched bandwidth of 59.9%, ranging from 3.43 to 11.1 GHz. Moreover, the bending analysis carried out for different scenarios show that the wideband behavior of the antenna is well preserved and the variation reaches a maximum of 1% variation

Antioxidant Activity and Inhibitory Effect of Some Commonly used Medicinal Plants against Lipid Per-Oxidation in Mice Brain

Background: The present study compares the protective properties of aqueous extracts of six medicinal plants, Phyllanthus emblica, Terminaliachebula (black and yellow), Terminalia arjuna, Balsamodendron Mukul and Alium sativum against lipid per-oxidation in mice brain.Methods: The antioxidant activities were analyzed by lipid per-oxidation assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, total antioxidantactivity and metal chelation.Results: The extracts (fruits and bark) showed inhibition against thiobarbituric acid reactive species (TBARS) induced by pro-oxidant (10 µM FeSO4) in mice brain. Moreover, the free radical scavenging activities of the extracts was evaluated by the scavenging of DPPH radical (IC50, 23.23±1.2 µg/ml (Phyllanthus emblica), 20.24±0.9 µg/ml (Terminalia chebula yellow) and 17.33±1.1 µg/ml (Terminalia chebula black), 19.44±0.45 µg/ml (Terminalia arjuna), 56.59±2.1 µg/ml (Balsamodendron Mukul) and . 200 µg/ml (Alium sativum).Conclusion: The higher antioxidant and inhibitory effect of Terminalia chebula black in this study could be attributed to its significantly higherphenolic content, Fe(II) chelating ability, reducing ability and free radical scavenging activity. Therefore oxidative stress in brain could be potentiallyprevented by the intake of these plants.Key words: Antioxidant activity, Balb c mice, iron chelation, phenolics, oxidative stress, medicinal plants

Alternating N2 gas injection as a potential technique for enhanced gas recovery and CO2 storage in consolidated rocks : an experimental study

The promotion of enhanced gas recovery (EGR) and CO2 storage is still shrouded in contention, and is not well accepted, due to the excessive in-situ CO2 mixing with the nascent natural gas. This adulterates the recovered CH4 and thus, results in a high sweetening process cost thereby making the technique impractical. This has not only limited the field application of EGR in actual projects to a few trails but renders it uneconomical. This study aims to present, experimentally, alternating N2 injection as a potential technique for EGR and CO2 storage in sandstone rock cores. A laboratory core flooding experiment was carried out to simulate a detailed process of unsteady-state methane (CH4) displacement using Bandera gray core plug. This was carried out at 40 0C, 1500 psig, and 0.4 ml/min injection rate by alternative injection of N2 and CO2 in succession designed to suit the application based on optimum operating conditions. The results show that both CO2 storage capacity and CH4 recovery improved significantly when gas alternating gas (GAG) injection was considered. The best results were observed at lower N2 cushion volumes (1 and 2 PV). Therefore, the GAG injection method with N2 as cushion gas can potentially increase both CO2 storage and CH4 recovery of the gas reservoir. This technique if employed will assert the current position and provide vital information for further researches aimed at promoting environmental sustainability and economic viability of the EGR and CO2 sequestration processes