Investigation of the reactivity of AlCl3 and CoCl2 toward molten alkali-metal nitrates in order to synthesize CoAl2O4

Cobalt aluminate CoAl2O4 powder, constituted of nano-sized crystallites, is prepared, involving the reactivity of AlCl3 and CoCl2 with molten alkali-metal nitrates. The reaction at 450 °C for 2 h leads to a mixture of spinel oxide Co3O4 and amorphous γ-Al2O3. It is transformed into the spinel oxide CoAl2O4 by heating at 1000 °C. The powders are mainly characterized by XRD, FTIR, ICP, electron microscopy and diffraction, X-EDS and diffuse reflection. Their properties are compared to those of powders obtained by solid state reactions of a mechanical mixture of chlorides or oxides submitted to the same thermal treatment

Influence du porte-greffe et de la date de récolte sur la qualité des fruits de la mandarine ‘Nadorcott’ pendant la conservation frigorifique

Cold storage is one of the main ways to coordinate harvesting and packinghouse operations for extending the marketing period. In Morocco, for the new citrus varieties, limited research has been undertaken on the evolution of the fruit quality during cold storage. In this paper, we present results of a cold storage trial of ‘Nadorcott’ mandarin fruits. Fruits were harvested from a rootstock trial carried out in SEBNAK orchard and stored in Mazaria packinghouse facilities in North-West of the Morocco. The objective of the study is to assess the effects of the harvest dates, the storage duration and three citrus rootstocks: ‘Carrizo’ citrange (CC), C-35 citrange (C35) and Citrus macrophylla L (M) on the internal quality and weight loss of the ‘Nadorcott’ mandarin fruits stored at 6 °C and 80% ±5 % humidity. Fruits were harvested at three dates and the quality parameters (juice content, titratable acidity, total soluble solids and weight loss) were evaluated after 0, 20, 40 and 60 cold-storage days. Fruit quality characteristics varied according to the rootstock type, storage duration and harvesting dates. At harvest, juice content was affected by different rootstocks: C-35 and CC showed the highest values, with about 50 % compared to that of M with only 44%. In addition, fruits harvested in March (D3) were less juicy than those harvested in January (D1) and early February (D2). The juice content falls more or less rapidly during the cold storage depending on the rootstocks and harvest dates. For the three harvest dates (D1, D2 and D3) and 60 days storage, the ‘Nadorcott’ mandarin fruits on M recorded the lowest juice percentage with values of 31, 38 and 30% respectively. At late period (D3), the acidity in fruit juice dropped to the lowest levels reaching a rate of 0.68 % for CC and M and 0.77 % for C-35. With regards to TSS, CC and C-35 had higher TSS (total soluble solids) percentage compared with fruits from trees on M. Date of harvest and cold-storage period have no significant effect on this parameter. Similarly, the weight loss of ‘Nadorcott’ fruit was not affected by the rootstock.La conservation à froid des fruits est l'un des principaux moyens pour coordonner les opérations de récolte et de conditionnement afin de prolonger la période de commercialisation. Au Maroc, pour les nouvelles variétés d'agrumes, les recherches menées sur l'évolution de la qualité des fruits en chambre froide sont peu nombreuses. Dans cet article, nous présentons les résultats d’un essai d’entreposage frigorifique des fruits de la mandarine ‘Nadorcott’. Les fruits ont été récoltés à partir d'un essai de porte-greffes installé dans le verger de la société SEBNAK et la conservation a été réalisée dans les chambres froides de la station de conditionnement, Mazaria, au nord-ouest du Maroc. L'objectif de l'étude est d'évaluer les effets de la date de récolte, de la durée de conservation et de trois porte-greffes d'agrumes: Citrange ‘Carrizo’ (CC), Citrange C-35 (C35) et Citrus macrophylla L (M) sur la qualité interne et le pourcentage de perte de poids des fruits de la mandarines 'Nadorcott' conservées à 6 °C et à 80% ± 5% d'humidité. Les fruits ont été récoltés à trois dates différentes et les paramètres de qualité (Teneur en jus, acidité titrable, solides solubles totaux et perte de poids) ont été évalués après 0, 20, 40 et 60 jours de stockage en chambre froide. Les résultats obtenus montrent que les paramètres de qualité des fruits variaient selon le porte-greffe, la durée de stockage et la date de récolte. Déjà à la récolte, la teneur en jus des fruits variait selon le porte-greffe: En effet, le C-35 et le CC présentaient les valeurs les plus élevées, avec environ 50% par rapport au M qui a donné un taux de jus de seulement de 44%. De plus, les fruits récoltés en mars (D3) étaient moins juteux que ceux récoltés en janvier (D1) ou le début de février (D2). La teneur en jus diminue plus ou moins rapidement lors de la conservation en chambre froide et ceci en fonction du porte-greffe et de la date de récolte. Pour les trois dates de récolte (D1, D2 et D3) et après 60 jours de stockage, les fruits de la mandarine ‘Nadorcott’ greffés sur le M ont enregistré le pourcentage de jus le plus bas avec des valeurs de 31, 38 et 30% respectivement. A la date de récolte tardive (D3), l'acidité du jus des fruits a chuté aux niveaux les plus bas en atteignant un taux de 0,68% pour le CC et le M et un taux de 0,77% pour le C-35. En ce qui concerne le TSS, le CC et le C-35 avaient un pourcentage de TSS (Solides solubles totaux) plus élevé que les fruits des arbres greffés sur le M. La date de récolte et la durée de stockage au froid n'ont pas d'effet significatif sur ce paramètre. De même, la perte de poids des fruits ‘Nadorcott’ n’a pas été affectée par le porte-greffe

Elaboration and characterization of dental plasters obtained from a Moroccan gypsum

Three experimental batches of  plaster elaborated from a Moroccan gypsum were characterized by conductimetry, dimensional variations measurements during setting and mechanical tests. Comparison with commercial dental plasters are undertaken to check whether these experimental materials possess good characteristics for dentistry applications

Insecticide Susceptibility Profile of Malaria Vector Populations from the Coastal and Mainland Areas of Akwa Ibom State, Nigeria

Development of resistance by different malaria vector populations to insecticides has become a big threat to malaria vector elimination. This study evaluated the susceptibility of Anopheles mosquito populations in Akwa Ibom State, Nigeria to permethrin (0.75%), deltamethrin (0.5%), lambdacyhalothrin (0.5%), alphacypermethrin (0.75%), Dichlorodiphenyltrichloethane (DDT), propoxur, bendiocarb and pirimiphosmethylin in World Health Organization (WHO) test tubes following standard protocols. The mosquitoes were obtained as aquatic forms and reared under laboratory conditions to adults. The adults were subjected to WHO susceptibility bioassays following standard procedures. Malaria vectors across the study sites were resistant to permethrin, deltamethrin, lambdacyhalothrin and alphacypermethrin insecticides. Full susceptibility to propoxur and bendiocarb was recorded across the sites. Full susceptibility to pirimiphosmethyl was recorded in populations from three sites. Nevertheless, population of the malaria vectors collected from Oron was resistant to pirimiphosmethyl. KDT50 and KDT95 estimated for each insecticide using a log-time probit model revealed that knockdown was more rapid for deltamethrin, lambdacyhalothrin, alphacypermethrin, propoxur, bendiocarb and pirimiphosmethyl than for DDT and permethrin  across the study sites. Morphological identification of all the mosquito samples used revealed that they were female Anopheles gambiae s.l. Sustained susceptibility of malaria vectors to pyrethriod is necessary for successful malaria control with insecticide treated nets and Indoor Residual Spraying (IRS). Emergence of focal points with insecticide resistance gives serious concern especially with the scale-up in distribution of pyrethriod treated nets to these areas. This may increase selection pressures due to overexposure. Further study to identify the exact resistance mechanism(s) of malaria vectors from these sites is recommended.</jats:p

Studies on the Population Dynamics and Distribution of Female Anopheles gambiae S. L. in Selected Local Government Areas (LGAs) of Kebbi State, North West, Nigeria

&lt;table&gt; &lt;tbody&gt; &lt;tr&gt; &lt;td&gt; &lt;p&gt;&lt;strong&gt;&lt;span&gt;Abstract&lt;/span&gt;&lt;/strong&gt;&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td&gt; &lt;p&gt;&lt;span&gt;Female &lt;em&gt;Anopheles&lt;/em&gt; mosquitoes are carriers of malaria which is a major public health problem in sub-Saharan Africa, where over 85- 90% of all global burden of malaria exists with up to 50% of all outpatient visits in areas with high malaria transmission and 30% - 50% of all hospital admissions are attributed to malaria. The disease kills 1.1 million people worldwide each year. Approximately, one million of these deaths are in Africa and an estimated 700, 000 of them are children. These malaria deaths account for one out of every four childhood deaths in Africa. Kebbi State has been reported to be one of the malaria endemic regions with high percentage of up to 50% prevalence. The study was conducted in three selected LGAs: Argungu, Bunza and Kalgo. In each of the LGAs, six communities are involved in which, four houses, each with both indoors and outdoors CDC light traps. Equally, in each of the six communities, 32 houses were selected randomly for pyrethroid spray catch (collection) (PSC), using the standard insecticide (Raid), with white plain cloth spread to ease collection of mosquitoes. Both collections from CDC indoors, outdoors and PSC collections were conveyed to the laboratory for screening of female &lt;em&gt;Anopheles gambiae &lt;/em&gt;mosquitoes using stereomicroscopes. A total of 16396 mosquitoes were collected between July and December. Highest number 8606(52.5%) were collected from Argungu, followed by Bunza with 4215 (25.7%) and the lowest from Kalgo LGA with 3575 (21.8%). Out of the total 16396 mosquitoes collected, 9095(55.5%) were collected from PSC, 5273(32.2%) from CDC Indoors and 2028(12.3%) were from outdoors collections. Results of monthly collection revealed that highest number 4709(28.9%) was collected from September, followed by 4227(25.9%), collected in the month of July, followed by 3582(22.0%) in August, 1840(11.3%) in October, 1163(7.12%) in November and lastly 788(4.82%) in December. It could be concluded that most of Kebbi State, being a flood plain located on a major river valley (Sokoto-Rima River), there are a lot of mosquito breeding sites, especially during the rainy season.&lt;span&gt;&nbsp;&nbsp; &lt;/span&gt;&lt;/span&gt;&lt;span&gt;There is therefore, urgent need for employment of integrated vector control method with special emphasis on larval source management, biological control, growth regulating insecticides in addition to the conventional chemical insecticidal control strategies in order to curve the level of transmission of malaria in the area&lt;/span&gt;&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td&gt; &lt;p&gt;&lt;strong&gt;&lt;span&gt;Keywords:&lt;/span&gt;&lt;/strong&gt;&lt;span&gt; &lt;/span&gt;&lt;strong&gt;&lt;em&gt;&lt;span&gt;Anapheles gambiae, &lt;/span&gt;&lt;/em&gt;&lt;/strong&gt;&lt;strong&gt;&lt;span&gt;Distribution, Dynamics, Kebbi, Population, &lt;/span&gt;&lt;/strong&gt;&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;/tbody&gt; &lt;/table&gt