Kajian potensi ekstrak bilberi sebagai penunjuk pH untuk memantau kesegaran makanan secara kromametri

Penunjuk pH sebagai suatu pendekatan untuk memantau kualiti atau kesegaran makanan semasa telah mendapat perhatian industri pembungkusan makanan. Penggunaan sumber semula jadi pigmen tumbuhan terutamanya daripada buah-buahan dan sayur-sayuran menjadi pilihan para pengguna untuk menggantikan pewarna sintetik dalam memastikan keselamatan makanan yang diambil setiap hari. Dalam kajian ini, ekstrak daripada bilberi telah digunakan sebagai pewarna sensitif pH. Perubahan warna sampel dikaji secara terperinci melalui kaedah kromametri dan juga kaedah spektrofotometri ultra-lembayung nampak. Warna merah terang terhasil dalam pH berasid, merah pudar pada neutral dan magenta ke kuning dalam pH beralkali. Keputusan kajian kromametri menunjukkan bahawa ekstrak bilberi berupaya mempamerkan perubahan warna yang jelas terhadap perubahan pH, iaitu terdapat perubahan nilai warna a* yang menyumbang kepada perubahan yang bererti dalam perbezaan warna keseluruhan (ΔE*). Nilai ΔE* juga ditentukan wujud hubungan linear dan kuantitatif terhadap julat pH tertentu. Oleh yang demikian, ekstrak bilberi didapati berpotensi sebagai bahan sensor untuk pH dalam membangunkan satu sensor pH bagi memantau kesegaran makanan terutamanya hasilan laut berbungkus memandangkan tahap kerosakan produk tersebut berkait rapat dengan perubahan pH ke arah alkali

Mollusques Fossiles de la Region de Sinda a L'est du Zaire

A study of the fossil moluscs has been carried out in eastern Zaire, mainly at Sinda in the Western Rift Valley (Lake Mobutu-Semliki Valley). The 1989 inventory of the collected molluscs had five speices (Caelatura bakeri, Mutela alata, Mutela rostrata, Iridina lepersonnei, and Aspatharia wissmanni) and the 1990 inventory, four species (Caelatura bakeri, Mutela alata, Mutela rostrata, and Aspatharia wissmanni). A biostratigraphic study will be conducted on these species after the conclusion of the geological study and the confirmation of our molluscs identification. From the available data, the fossil molluscs pertain to Miocene and Pliocene fauna

Growth and demography of populations of Biomphalaria pfeifferi (gastropoda, planorbidae) in the laboratory

The growth and demography of the freshwater snail Biomphalaria pfeifferi, an intermediate host of the parasitic worm Schistosoma mansoni in Eastern Zaire, were investigated in the laboratory under two conditions of crowding. Both individual and population growth were depressed by crowding. Crowding reduced growth rate and all the variables and parameters related to reproduction (fecundity, instantaneous birth rate, net reproduction rate), but did not affect maximum size, survivorship, instantaneous death rate and life expectancy. The mechanism involved in these effects is likely to be exploitation competition for especially profitable food items such as diatoms. © 1987 The Malacological Society of London.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Population dynamics of the freshwater snail Biomphalaria pfeifferi in Eastern Zaïre

The population dynamics of the freshwater snail Biomphalaria pfeifferi, an intermediate host of the parasitic worm Schistosoma mansoni, was studied in the Virunga stream in Eastern Zaïre.Methods are developed to estimate age-specific survivorship from regular quadrat-sampling data without assuming a constant mortality rate, and to approximate age-specific fecundity when the fecundity function is known in the laboratory.The population dynamics in the field was found to be very different from that in the laboratory: it is basically discontinuous, with one main generation per year; a massive mortality occurs after hatching; fecundity is reduced considerably; and there are marked seasonal variations in both survivorship and fecundity. Time-dependent demographic parameters were estimated by month instead of by cohort. They show that the environmental conditions are favourable to an increase of the population only during a short period of the year. The intrinsic rate of natural increase, r, was found to be well correlated with the changes in egg density.The environmental factors determining the population dynamics in the Virunga are discussed; current speed seems critical. © 1987 The Malacological Society of London.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Shade as a means of ecological control of Biomphalaria pfeifferi

Species of Biomphalaria are attracted to light and negatively affected by darkness. Artificial shading of a breeding-site eliminated a population of B. pfeifferi within six weeks. The site was recolonized by eight weeks after the shade was removed. The time taken for recolonization suggests that shade acts not only by affecting snail behaviour but also indirectly by removing the diatoms which are food for the snails. The use of natural shade for ecological control of some snail vectors of schistosomiasis deserves, at least, careful consideration.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

FOSSIL MAMMALS FROM THE NEOGENE STRATA IN THE SINDA BASIN< EASTERN ZAIRE

Since 1989, a geological and paleontological expedition has been carried out in the Zairean part of the Western Rift Valley. During two field seasons, more than 600 fossil remains were collected in the Sinda basin, Gaty, Haut-Zaire, mainly as surface finds. This fossil collection contains 52 mammalian fossils which comprise the following taxa; ? Agriotherium, four proboscidean groups such as Prodeinotherium, ?Anancus, Mammuthus subplanifrons and Stegodon kaisensis, two Rhinocerotidae, i.e., ?Aceratherium and Brachypotherium, ?Sivatherium, Hippopotamus, and a bovid. The Sinda fauna is composed of both Miocene and Pliocene mammals and suggest that the strata including the fossils are of late Miocene to early Pliocene in age. This fauna resembles that from the Nkondo formation which is located in the Ugandan side of the Western Rift Valley. The composition of the fauna from the Sinda area may indicate a different paleoenvironment (probably more humid) in this area from that in contemporary East Africa. RESUME Depuis 1989, une expedition geologique et paleontologique est realisee dans la partie zairoise de la branche occidentale du Rift. Durant deux saisons, plus de 600 restes fossiles ont ete collectele basin de Sinda, Gaty, haut-za?re, principalement comme decouvertes de surface. Cette collection fossile contient 52 mammiferes fossiles qui comprennent les taxa suivant; ?Agriotherium, qutre groupes proboscidean tels que Prodeinotherium, ?Anancus, Mammuthus subplanifrons et Stegodon kaisensis, deux Rhinocerotidae par exemple, ?Aceratherium et Brachypotherium, ?Sivathrium, Hippopotamus, et un bovide. La faune de Sinda est composee des mammiferes du miocene et du pliocene et suggere que le strate inclus les fossils sont de l'age du miocene superieur au debut pliocene Cette faune ressemble celle de Nkondo formation qui est situee dans la partie ougandaise du Rift Occidental. La composition de la faune de l'aire de Sinda devra indique un paleoencironement different (probablement plus humide) dans cette aire de celui en l'est-aficain contemporain

Geology of the Sinda-Mohari Region, Haut-Zaire Province, Eastern Zaire

The Sinda-Mohari region is topographically divided into the Mutimba plateau, hilly land and Semliki Plain. The hilly land is underlain by Precambrain basement rocks, Sinda Beds, Higher Terrace Deposits, Middle Terrace Deposits, Lower Terrace Deposits, and Alluvium (Recent river floor deposits). The Sinda Beds are subdivided into the lower, middle and upper members. The lower member consists of clayey white coarse sand and yields such mammal fossils as Bovidae, etc. from the upper part. The middle member is characterized by alternating sand and mud beds. The upper member is composed of alternating thicker beds pf sand and mud and contains such mammal fossils as Predeinotherium, etc. Generally, the Sinda Beds gently dip south to southeast. Folds parallel the northern boundary faults. An inferred fault is drawn parallel just north of these folds. The context of geological phenomena from the older to the younger in this region is as follows: 1) formation of an extensive sedimentary basin by downwarping, 2) deposition of the Sinda Beds, 3)long-term denudation and peneplanation, 4) intense activity of the northern boundary faults and formation of the Higher Terrace Deposits, 5) activity of the southeastern boundary fault, 6) formation of the present Semliki Plain as the floor of the rift valley, 7) completion of the present drainage system, and 8) formation of the Middle and Lower Terrace Deposits within the deep valleys

Essaie de production et composition chimique des asticots élevés sur des substrats locaux au Sud-Kivu (RDC)

Objectifs : Ce travail visait à évaluer la productivité des substrats disponibles localement ainsi que la composition chimique des asticots élevés sur ces substrats afin de proposer aux éleveurs du milieu les sources alternatives des protéines, peu concurrentielles avec l’homme. Méthodologie et résultats : L’expérience était menée dans un hangar en bâche ouvert, de 11 m de long, 5 m de large et 2 m de hauteur au CRSN/Lwiro. Elle a porté sur 9 substrats dont 3 d’origine végétale et 6 d’origine animale pour produire les asticots. Après la capture manuelle des mouches sur différents substrats, l’identification a été faite sur base leurs caractères morphologiques au laboratoire d’entomologie du CRSN/Lwiro. Pour les paramètres de production, 40 asticots par traitement ont été prélevés afin de déterminer la taille moyenne des asticots. Quant à la composition chimique, les échantillons d’asticots ont été séchés à l'étuve à 70°C puis broyés et directement analysés pour déterminer les teneurs en glucide, protéines brutes et en matières grasses. Les résultats obtenus révèlent la présence de trois familles de mouches : Calliphoridae, Muscidae et Sarcophagidae qui sont impliquées dans la ponte sur différents sous-produits utilisés comme substrats. Il a été aussi observé que les substrats d’origine animale sont les plus productifs en asticots par rapport à ceux d’origine végétale y compris les crottes de chèvres dont la production était nulle (0,00756˂0,05). Quant à la composition chimique des larves, elle dépend en majeur partie des substrats alimentaires sur lesquels elles sont produites, mais également de leur stade de développement. Ainsi, les larves du 4e cycle de production sont plus riches en protéine, glucide et lipide que celles du 1re, 2e et 3e cycle. Conclusion et application des résultats : Enfin, les asticots de ces trois familles de mouches peuvent donc constituer les sources locales des protéines surtout à leur 4e cycle et ainsi réduire le coût exorbitant lié à la nutrition animale afin de combattre la concurrence alimentaire entre l’homme et les animaux. La valorisation des déchets produisant les asticots constitue aussi un moyen d’assainir les milieux et de lutter contre la pollution atmosphérique.Mots clés : Asticots, substrats, productivité, composition chimique, RD Cong