Prospects and Challenges of Developing Plant-Derived Snake Antivenin Natural Products: A Focus on West Africa

Snakebite envenomation (SBE) is an important public health issue that is now receiving renewed attention following its reclassification as a Neglected Tropical Disease (NTD). Most incidences occur in rural areas of resource-limited countries, as such, timely and appropriate medical care for SBE is often inaccessible. The administration of anti-snake venom serum (ASV) is the only effective definitive treatment of SBE, but treatment failure to available ASVs is not uncommon. Emerging evidence highlights the potential of small-molecule compounds as inhibitors against toxins of snake venom. This presents an encouraging prospect to develop an alternative therapeutic option for the treatment SBE, that may be amenable for use at the point of care in resource-constraint settings. In view of the pivotal role of natural products in modern drug discovery programmes, there is considerable interest in ethno-pharmacological mining of medicinal plants and plant-derived medicinal compounds toward developing novel snake venom-neutralising therapeutics. In this review, we compile a collection of medicinal plants used in the treatment of SBE in West Africa and highlight their promise as potential botanical drugs or as sources of novel small-molecule compounds for the treatment of SBE. The challenges that must be surmounted to bring this to fruition including the need for (sub) regional collaboration have been discussed.     

Spectral coded phase bipolar OCDMA technological implementation thanks to low index modulation filters

Telecommunication Systems - Optical code division multiple access (OCDMA) systems are attracting an increasing interest in optical fiber communication. This is due to the various advantages that...     

Experimental investigation of the mixing performance of a lobed jet flow

An experimental investigation of flow in a turbulent isothermal air lobed jet is presented. A lobed jet is compared, in the near field, with an isothermal axisymmetric jet with the same exit Reynolds number in terms of dynamics and mixing enhancement. It was found that the streamwise variation of the volumetric flow rate is characterized by a slope is more than twice larger than that for the reference circular jet. This high entrainment rate is governed, at the same time, by the turbulent structures generated by the asymmetric shape of the nozzle and by the high convection in these structures induced by the inner and outer penetration angles of their lobes. Published in Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 102–107, February–March, 2008.     

Resonance effect of insulated negative current rail in a subway network

A modeling technique of a subway network is performed in order to quantify the effect of insulated negative current rail on resonance frequencies. A DC track circuit is modeled by means of transmission line modeling (TLM) approach to perform line current and voltage calculation. Impedance and admittance required by TLM equations are first derived. System impedance is expressed in terms of internal and external impedance. The former is calculated using exact expression of a cylindrical conductor whereas the external impedance is taken as the sum of conductor's reactance considering a perfect conducting plane and the ground impedance. The well-known Carson's formulas for ground impedance are compared to Sunde's one to investigate frequency range applicability of the former. Simulations reveal that Carson's expressions are valid for frequencies up to 50 kHz. It appears, however, that using Cason's formulas for higher frequencies lead to underrating ground impedance. To investigate the accuracy impact of internal impedance, ground impedance and inductance on resonance frequencies, a sensitivity analysis is performed. A noticeable resonance effect is observed at 8 kHz for a 10 km length rail. Simulation results show the network impedance effect on track current and voltage.     

Thermal-hydraulic behavior of the NUR nuclear research reactor during a fast loss of flow transient

Nuclear safety analysis remains of crucial importance for both the design and the operation of nuclear reactors. Safety analysis usually entails the simulation of several selected postulated accidents, which can be divided into two main categories, namely reactivity insertion accident (RIA) and loss of flow accident (LOFA). In this paper, thermal-hydraulic simulations of fast LOFA accident were carried out on the new core configuration of the material test research reactor NUR. For this purpose, the nuclear reactor analysis PARET code was used to determine the reactor performance by calculating the reactor power, the reactivity and the temperatures of different components (fuel, clad and coolant) as a function of time. It was observed that during the transient the maximum clad temperature remained well below the critical temperature limit of 110 °C, and the maximum coolant temperature did not exceed the onset of nucleate boiling point of 120 °C. It is concluded that the reactor can be operated at full power level with sufficient safety margins with regard to such kind of transients.     

Numerical study of the wake induced by a porous disk under deflected inflow

This study examines the wake of a porous disk that generates a velocity deficit equivalent to that of a wind turbine. Three-dimensional unsteady numerical simulations based on the finite volume method are performed. The URANS-SST (k–ω) model is applied for the turbulence closure. Two investigations are carried out in this study: (i) the influence of the disk porosity on the wake, for porosities values (p) ranging from 0 to 0.55 in the case of a perpendicular flow; and (ii) the influence of the yaw angle on the wake deviation, for yaw angles ranging from 5° to 30°. Good agreements with the available experimental data are obtained for the mean x-velocity component. The results confirm that wake length increases as porosity decreases. For nonporous disks, most part of the fluid is deflected toward the mast and above the disk. The y-velocity contours highlight two contra-rotating vortices in the vicinity of the disk. In both cases (nonporous and porous disks), a high turbulent kinetic energy is obtained near the disk area, with a higher maximum value for the nonporous disk.     

Aging and lineup performance at long retention intervals: Effects of metamemory and context reinstatement.

Young (18–30 years) and older (62–79 years) adults (N?=?96) engaged in a 20-min live interaction with the future target in a lineup task. One month later, participants were interviewed about the events in the prior encounter (with or without context reinstatement), and then they saw a target-present (TP) or target-absent (TA) lineup. The lineup was followed by the Benton Face Recognition Test (A. Benton, A. Sivan, K. Hamsher, N. Varney, & O. Spreen, 1994), which correlated positively with accuracy in TP, especially for young adults. False identification in TA was associated with (a) higher scores on a memory self-efficacy scale and (b) higher recall of information about the initial event, although only for seniors. Results suggested that age-related increases in false identification generalize to ecologically valid conditions and that seniors' performance on lineups is negatively related to verbal recall as well as to self-reports of satisfactory experiences with memory in life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fatty esters of cellulose from olive pomace and barley bran: Improved mechanical properties by metathesis crosslinking

Agricultural wastes such as olive pomace and barley bran have been transformed in plastic by esterification with fatty acid chlorides after acidic or alkaline delignification. These esterifications were carried out in homogenous solution DMA/LiCl by classical heating or microwave activation. The plastics obtained were characterized by IR and NMR spectra, and tested for their mechanical properties and potentiality of biodegradation. The mechanical properties were improved by olefin metathesis of undecylenic ester from olive cellulose. delignification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 751–755, 2006     

Water quality before and after dam building on a heavily polluted river in semi‐arid Algeria

The impact of the construction and management of a reservoir on a polluted stream in a semi‐arid region has been highlighted using physico‐chemical indicators. The Tafna river (Algeria) collects heavily polluted wastewater from the town of Maghnia and from several factories. Organic pollution comes from domestic sewage and from food industries. Ore treatment industries discharge very acidic wastewater. Temperature, pH, conductivity, chloride, dissolved oxygen, biological oxygen demand (BOD), and nitrogen compounds have been surveyed between 1996 and 2001, before and after the construction of the dam. The change in each parameter is compared between sites located upstream and downstream from the dam. The spatio‐temporal evolution of the organic pollution indicators was highlighted by ANOVA and principal component analysis. By enhancing sedimentation of the organic matter, the reservoir makes possible a significant decline in the BOD downstream of the dam, but increases NH₄ concentration at the downstream sites. The pollution is diluted during high flows and dam releases. Conversely, during low flow periods, mineralization of organic matter is higher in the lower Tafna. Copyright © 2004 John Wiley & Sons, Ltd.     

Signal strength based link sensing for mobile ad-hoc networks

Mobility causes frequent link failures in ad-hoc networks. This results in a severe degradation of performance specially in case of high mobility of nodes. This is because the routing protocols for ad-hoc networks are not equipped to handle high mobility. In this paper, we have presented a new link management algorithm to locally manage links. This new mechanism is based on signal strength measurements. Researchers over the years have presented approaches which use signal strength measurements but their focus has been on re-active protocols while our algorithm is aimed at pro-active protocols. Pro-active protocols are used since they provide greater flexibility to take advantage of the mesh configuration. We develop the hysteresis mechanism provided by OLSR, based on hello packets, to include signal strength measurements. The mechanism in OLSR uses Hello packets received/lost to decide to establish link or not. The problem with this approach arises when there is high mobility in which case the time to break the link and use a new path becomes significant. To overcome this, we propose to use signal strength to determine if the link-quality is improving or deteriorating. This combination of the two mechanisms, makes the link management more robust and also helps in anticipating link breakages thereby greatly improving performance.