Effect of Accelerated Laboratory Aging on Selected Electrical Properties of Medium-voltage Heat Shrink Cable Joints

Cross linked polyethylene (XLPE) cables are being used extensively in high-voltage power transmission and distribution networks around the world. However, such joints suffer high failure rates in extreme weather conditions. To investigate this issue, selected properties of 15-kV heat shrinkable XLPE cable joints produced by four manufacturers that are widely being used by electric power utilities in Saudi Arabia were evaluated before and after accelerated multi-factor aging. Aging stresses included high voltage, temperature cycling, and periodic applications of switching impulses while keeping joints in air as well as in water. Partial discharge characteristics, dissipation factor at 60 and 0.01 Hz, and breakdown voltages were measured for un-aged and aged joint samples. The results show that partial discharge characteristics supplemented with a 0.01-Hz dissipation factor provide useful diagnostic information about the condition of such joints. Moreover, these properties also provide useful information about the comparative performance of joints produced by different manufacturers.     

Swelling and aspirin release study: cross-linked pH-sensitive vinyl acetate-co-acrylic acid (VAC-co-AA) hydrogels

The objective of this work was to develop new pH-sensitive hydrogels to deliver gastric mucosal irritating drugs to the lower part of the gastrointestinal tract. For this purpose, cross-linked vinyl acetate-co-acrylic acid (VAC-co-AA) hydrogels were synthesized by using N, N, methylene bisacrylamide (MBAAm) as a cross-linking agent. Different ratios of 90:10, 70:30, 50:50, 30:70, and 10:90 of VAC-co-AA were synthesized. All of the compositions were cross-linked using 0.15, 0.30, 0.45, and 0.60 mol percent MBAAm. Swelling and aspirin release were studied for 8 hour period. The drug release data were fitted into various kinetic models like the zero-order, first-order, Higuchi, and Peppas. Hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. In addition to the above, these hydrogels were loaded with 2%, 8% and 14% w/v aspirin solutions, keeping the monomeric composition and degree of cross-linking constant. In conclusion, it can be said that aspirin can be successfully incorporated into cross-linked VAC/AA hydrogels and its swelling and drug release can be modulated by changing the mole fraction of the acid component in the gels.     

Integrating tobacco control into health and development agendas

Tobacco use is one of the major risk factors for non-communicable diseases, with a profound impact on resource-poor low-income and middle-income countries such as India, where tobacco use is high and where socioeconomic as well as health inequalities are rampant. Effective implementation of the Framework Convention on Tobacco Control requires multisectoral efforts that can fructify through integration of tobacco control into broader health and development agendas such as food and water security, environment, the right to education and human rights. The global tobacco control community will need to explore innovative partnerships beyond its traditional confines and build a global coalition that supports tobacco control by partnering with others having convergent concerns on common determinants. A firm political commitment and intersectoral coordination between government and non-government agencies is paramount in order to implement effective tobacco control programmes. Integration of tobacco control into other health and development agendas as described in this paper has the potential to contribute to the achievement of all the eight United Nations Millennium Development Goals. This paper explores why the whole of government should accord a high priority to tobacco control, and how this integration could be achieved.     

Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Electrochemical Sensor

The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe₃O₄ NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe₃O₄ NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe₃O₄ NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe₃O₄ NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01–0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.     

Bandwidth‐Efficient Selective Retransmission for MIMO‐OFDM Systems

In this work, we propose an efficient selective retransmission method for multiple‐input and multiple‐output (MIMO) wireless systems under orthogonal frequency‐division multiplexing (OFDM) signaling. A typical received OFDM frame may have some symbols in error, which results in a retransmission of the entire frame. Such a retransmission is often unnecessary, and to avoid this, we propose a method to selectively retransmit symbols that correspond to poor‐quality subcarriers. We use the condition numbers of the subcarrier channel matrices of the MIMO‐OFDM system as a quality measure. The proposed scheme is embedded in the modulation layer and is independent of conventional hybrid automatic repeat request (HARQ) methods. The receiver integrates the original OFDM and the punctured retransmitted OFDM signals for more reliable detection. The targeted retransmission results in fewer negative acknowledgements from conventional HARQ algorithms, which results in increasing bandwidth and power efficiency. We investigate the efficacy of the proposed method for optimal and suboptimal receivers. The simulation results demonstrate the efficacy of the proposed method on throughput for MIMO‐OFDM systems.