Predicting and controlling the dynamics of infectious diseases

This paper introduces a new optimal control model to describe and control the dynamics of infectious diseases. In the present model, the average time of isolation (i.e. hospitalization) of infectious population is the main time-dependent parameter that defines the spread of infection. All the preventive measures aim to decrease the average time of isolation under given constraints

Dynamics of Ebola epidemics in West Africa 2014

This paper investigates the dynamics of Ebola virus transmission in West Africa during 2014. The reproduction numbers for the total period of epidemic and for different consequent time intervals are estimated based on a newly suggested linear model. It contains one major variable - the average time of infectiousness (time from onset to hospitalization) that is considered as a parameter for controlling the future dynamics of epidemics. Numerical implementations are carried out on data collected from three countries Guinea, Sierra Leone and Liberia as well as the total data collected worldwide. Predictions are provided by considering different scenarios involving the average times of infectiousness for the next few months and the end of the current epidemic is estimated according to each scenario

CONSUMER PREFERENCES FOR QUALITY CHARACTERISTICS ALONG THE COWPEA VALUE CHAIN IN NIGERIA, GHANA AND MALI

The production and trade of cowpea (Vigna Uniculata), called “blackeyed peas” in the US, are a growing business for farmers and merchants serving the rapidly expanding urban areas of West and Central Africa. Cowpea fits the needs of the urban poor. It is an inexpensive source of protein that does not require refrigeration. A better understanding of consumer preferences for cowpea is essential to market development. The main objective of the study was to determine the cowpea grain quality characteristics that command a price premium or provoke a discount in Ghanaian, Malian and Nigerian markets. Specifically, the study looked at the impact of the grain size, texture, color, eye color, and bruchid-damaged grains on cowpea market prices. The data for the study were collected from six markets in Ghana; four markets were in the capital city of Accra and two markets in Kumasi. In Mali, two markets were surveyed, Marché de Sabalibougou and Marché Medine. In Nigeria three markets were surveyed, Iddo in Lagos; Monday, in Maiduguri; and Dawanau in Kano. Hedonic pricing methods provide a statistical estimate of premiums and discounts. The results of the study indicated that cowpea consumers in Ghana, Mali and Nigeria are willing to pay a premium for large cowpea grains. Cowpea consumers discount grains with storage damage from the very first bruchid hole. The impact of price on other cowpea quality characteristics such as skin color and texture, and eye color varies locally. Implications for development of the cowpea value chain include: 1) breeders and cowpea production researchers should identify cost-effective ways to increase cowpea grain size because larger grain size is almost universally preferred, and 2) entomologists and storage experts should develop and transfer improved storage technologies to reduce damage discounts, and 3) serving local markets requires a portfolio of grain skin color, eye color and skin texture combinations.Cowpeas market chains, consumer preference, hedonic price analysis

Synthesis, characterisation and Pickering emulsifier performance of poly(stearyl methacrylate)–poly(N-2-(methacryloyloxy)ethyl pyrrolidone) diblock copolymer nano-objects via RAFT dispersion polymerisation in n-dodecane

A near-monodisperse poly(stearyl methacrylate) macromolecular chain transfer agent (PSMA macro-CTA) was prepared via reversible addition–fragmentation chain transfer (RAFT) solution polymerisation in toluene. This PSMA macro-CTA was then utilised as a stabiliser block for the RAFT dispersion polymerisation of a highly polar monomer, N-2-(methacryloyloxy)ethyl pyrrolidone (NMEP), in n-dodecane at 90 °C. 1H NMR studies confirmed that the rate of NMEP polymerisation was significantly faster than that of a non-polar monomer (benzyl methacrylate, BzMA) under the same conditions. For example, when targeting a PSMA14–PNMEP100 diblock copolymer, more than 99% NMEP conversion was achieved within 30 min, whereas only 19% BzMA conversion was obtained on the same time scale for the corresponding PSMA14–PBzMA100 synthesis. The resulting PSMA–PNMEP diblock copolymer chains underwent polymerisation-induced self-assembly (PISA) during growth of the insoluble PNMEP block to form either spherical micelles, highly anisotropic worms or polydisperse vesicles, depending on the target DP of the PNMEP chains. Systematic variation of this latter parameter, along with the solids content, allowed the construction of a phase diagram which enabled pure morphologies to be reproducibly targeted. Syntheses conducted at 10% w/w solids led to the formation of kinetically-trapped spheres. A monotonic increase in particle diameter with PNMEP DP was observed for such PISA syntheses, with particle diameters of up to 462 nm being obtained for PSMA14–PNMEP960. Increasing the copolymer concentration to 15% w/w solids led to worm-like micelles, while vesicles were obtained at 27.5% w/w solids. High (≥95%) NMEP conversions were achieved in all cases and 3[thin space (1/6-em)]:[thin space (1/6-em)]1 chloroform/methanol GPC analysis indicated relatively high blocking efficiencies. However, relatively broad molecular weight distributions (Mw/Mn > 1.50) were observed when targeting PNMEP DPs greater than 150. This indicates light branching caused by the presence of a low level of dimethacrylate impurity. Finally, PSMA14–PNMEP49 spheres were evaluated as Pickering emulsifiers. Unexpectedly, it was found that either water-in-oil or oil-in-water Pickering emulsions could be obtained depending on the shear rate employed for homogenisation. Further investigation suggested that high shear rates lead to in situ inversion of the initial hydrophobic PSMA14–PNMEP49 spheres to form hydrophilic PNMEP49–PSMA14 spheres

Isolasi dan Karakterisasi Senyawa Aktif Repellent Nyamuk dari Ekstrak Rimpang Jeringau (Acorus Calammus)

Telah dilakukan isolasi dan karakterisasi senyawa aktif repellent pada rimpang jeringau (Acorus calammus. L). Penelitian diawali dengan mengekstrak 500 gram serbuk rimpang jeringau (Acorus calammus. L) dengan pelarut metanol menggunakan teknik maserasi. Ekstrak kental metanol difraksinasi dengan pelarut n-heksan. Identifikasi senyawa yang terkandung pada rimpang jeringau dilakukan dengan uji fitokimia pada ekstrak kental dan masing-masing fraksi. Melalui kromatografi kolom, ekstrak kental fraksi n-heksan menghasilkan 49 fraksi kemudian diuji menggunakan KLT. Isolat murni yang positif pada uji flavonoid dianalisis keberadaan gugus fungsinya dengan spektrofotometer IR dan UV-Vis. Hasil analisis dengan Spektrofotometer IR menunjukkan gugus fungsi adanya ulur O-H, ulur C-H, ulur C=O, ulur C=C aromatik, tekuk O-H, tekuk C-H dan ulur C-O alkohol. Sedangkan untuk UV-Vis menunjukkan 2 pita dengan serapan gelombang maksimum pada 304,78 dan 253,76 nm. Senyawa yang diduga adalah senyawa flavonoid yang merupakan senyawa aktif repellent nyamuk

Medicinal plants used in the management of diabetes mellitus 2015

Diabetes mellitus is one of the common endocrine disorders prevalent in almost all of the countries. This chronic pathology is characterized by hyperglycemia caused by defective insulin action, insulin secretion, or the combination of both. Prolonged persistence of elevated blood glucose level consequently caused a series of complications such as nephropathy, retinopathy, and cardiomyopathy. Currently available synthetic drugs for treating this disease are found to be associated with many adverse effects. The use of plants in medicine is an age-long practice in various parts of the globe for both preventive and curative purposes. Several warnings have been issued over lack of quality control, scientific evidence for the efficacy, and potential adverse effects of herbal remedies including hepatotoxicity, nephrotoxicity, cardiotoxicity, and reproductive toxicity among others. Despite all of these, reliance on herbs as medicine for the management of diabetes mellitus is still much practiced by a large proportion of the world population because they are readily available and affordable with perceived reduced toxicity. Therefore, with the upsurge of interests in medicinal plants, there is a need for thorough scientific investigations of these plants for both efficacy and potential toxicity. In this issue, we present some recent advances in the use of medicinal plants for treating diabetes mellitus. B. Pang et al. (“Innovative Thoughts of Treating Diabetes from the Perspective of Traditional Chinese Medicine”)presented a review article on the contribution of traditional Chinese medicine to the development of alternative and complementary medicine for the treatment and prevention of diabetes mellitus. In another paper (“Effect of Rhizoma Coptidis (Huang Lian) on Treating Diabetes Mellitus”), B. Pang et al. discussed the efficacy and safety of Rhizoma Coptidis in the treatment of diabetes mellitus. In another study (“Evaluation of the Effects of Cornus mas L. Fruit Extract on Glycemic Control and Insulin Level in Type 2 Diabetic Adult Patients: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial”), R. Soltani et al. reported the results of a clinical trial on the effect of Cornus mas L. fruit extract on hyperglycemia in type 2 diabetic patients. In addition, W. Liu et al. (“The Effects of Chinese Medicine on Activation of Wnt/β-Catenin Signal Pathway under High Glucose Condition”) present a valuable review on some compounds implicated in the regulation of Wnt/β-catenin signal pathway as a mechanism of action involved in the antihyperglycemic activity from Chinese medicine. Furthermore, A. O. T. Ashafa and M. I. Kazeem (“Toxicopathological Evaluation of Hydroethanol Extract of Dianthus basuticus in Wistar Rats”) reported on the effects of Dianthus basuticus (a Basotho plant with acclaimed antidiabetic activity) on some biochemical parameters and histology of Wistar rats. Finally, X.-J. Li et al. (“TCM Formula Xiaoyaosan Decoction Improves Depressive-Like Behaviors in Rats with Type 2 Diabetes”) evaluated the effect of traditional medicine formula, Xiaoyaosan, on the cognitive function of diabetic rats. After the first volume of this special issue that was published in 2014, we hope that this issue will present additional valuable information for scientists and clinicians