Moisture Sorption Characteristics of Dehydrated in-shell African Walnut (Tetracarpidium conophorum)

Moisture sorption isotherms are useful thermodynamic tools for determining water interactions within food systems and providing information that can assist in optimizing food processing operations such as drying, mixing, packaging and storage, as well as to maximize retention of quality parameters such as colour, aroma, texture, and nutrient. Moisture sorption isotherm characteristics of African walnut were evaluated at three different temperatures (28, 33 and 38°C) and relative humidity range of 11.20 - 97.00 % using gravimetric method; five mathematical models (GAB, BET, Peleg, Smith and Ferro Fontan) were fitted into the experimental data. Sorption isotherms of the dehydrated walnut gave type II (S-shaped) isotherms according to BET classification. Temperature had significant effect on the equilibrium moisture content (EMC). A nonlinear regression analysis method was used to evaluate the constants of sorption models. The models were evaluated statistically by calculating coefficient of determination (R2), the mean relative percentage error (P) and the reduced chi-square (λ2). The BET model gave the best fit for the obtained data among the tested models with R2 value of 0.9892. Calculated monolayer moisture (Mo) content from BET ranged from 5.018 to 7.922% db for adsorption and 9.842 to 10.143% db for desorption respectively

Effects of Kaolin Particle Size and Annealing Temperature on the Resistivity of Zinc- Kaolin Composite Resistors

The effects of kaolin particle sizes on the resistivity of zinc-kaolin composite resistors have been investigated. The composite resistors have been produced from kaolin particle sizes ranging from 0.063 mm to 0.5 mm. The resistors were produced in a mould to a dimension of 65 mm x 6.5 mm x 3.2 mm with dry zinc and kaolin powders to which a drop or two of sodium silicate have been added as a binder. The resistors were annealed at temperatures ranging from 300\ub0C to 1000\ub0C in steps of 100\ub0C for composites of 0%, 5%, 40% and 60%(vol.) zinc content. Results showed that composite resistivity at all the zinc concentrations considered and at all annealing temperatures increased exponentially with increasing kaolin particle size. The effect of annealing showed that composite resistance is highest for composites annealed at 1000\ub0C and lowest for cermets annealed between 500 oC and 600\ub0C. Composite resistance increased with increasing kaolin particle size due to the large contact area presented by the insulating kaolin particles resulting in reduction of the number of zinc particle-particle contact. The results from this study will help in the development of conducting ceramics which could find use in chemical industries as electrodes in environments not conducive for metallic electrodes

Size effects in ruthenium-based thick-film resistors: rutile vs. pyrochlore-based resistors

The size effect, namely the change of sheet resistance, R, as a function of resistor length, has been investigated in layers whose conductive phase evoves from Pb-rich (Ru-deficient pyrochlores) to Pb2Ru2O6.5 and finally to RuO2 by increasing the firing temperature. It is found that Bi diffusion from the terminations is responsible for lower sheet resistance values in shorter resistors whatever the conductive phase is. On the contrary, Ag diffusion is responsible for lower sheet resistance values in shorte resistors only in the case of ruthenate conductive grains while the reverse is observed in RuO2-based layers. Size effect can be suppressed with Pt/Au-based terminations provided that Bi is contained and with Au-metallorganic-based contact provided that the peak firing temperature is not too high

Effects of Temperature on Morphological, Structural and Optical Characteristics of CdTe Films for PV Applications

Cadmium telluride (CdTe) is a direct band gap semiconductor for direct light-to-electricity conversion. The films are promising photovoltaic materials for CdS/CdTe solar cells because of its energy band gap of 1.5 eV and higher absorption co-efficient (>104cm-1). This work presents the characterization of 1 μm CdTe films for photovoltaic applications. The films were deposited on cleaned glass substrates using thermal evaporation. The effect of annealing temperatures (as deposited, 400°C and 500°C) on morphological, structural and optical characteristics of CdTe films was investigated for an hour and characterized with Scanning Electron Microscope (SEM), Powder X-ray diffraction (PXRD) and UV-Visible spectrophotometer. The results revealed that the reflectance characteristics of CdTe films depend on the wavelength of electromagnetic spectra. The maximum percentage optical transmittance of CdTe films for as-grown, 400°C and 500oC films were 59%, 60% and 58% respectively at 800 nm wavelength. The absorbance decreases with increasing in wavelength and was found to be 1.65, 1.25 and 0.85 % for the as-grown, 400°C and 500oC films respectively. The absorption coefficient exhibits higher values in the shorter wavelength and decreases as the wavelength and temperatures increases and the band gap becomes wider. The SEM analyses showed that the films were homogenous and free from crystal defects. The results revealed that 1 μm CdTe film may be used as absorber layer in CdS/CdTe thin film solar cells. Keywords: CdTe, Glass substrate, Thermal evaporation, Annealing temperature, Energy band ga

RESPONSES OF DIFFERENT TOMATO VARIETIES TO DISEASE STRESS UNDER DIFFERENT CONDITIONS OF GRAVITY

A study was carried out to evaluate the responses of different tomato varieties to fungal disease stress under different conditions of gravity, in Lafia, Nasarawa State Nigeria. Seeds of three local tomato varieties namely; UTC, Teema and Dan Syria were plated on plant agar inoculated with culture filtrates of Sclerotinia sclerotiorum and Pythium ultimum, and rotated on a clinostat at a speed of 20 revolutions per minute (rpm) for 96 hours in a dark growth chamber. Seedlings of Dan Syria subjected to the condition of normal gravity had the highest Frequency of germination (79.61%), seedling height (4.01mm) and stem girth (0.19mm). Teema had thehighest width of vascular bundles (1.18mm) under normal gravity condition. Under conditions of microgravity, the highest number of trichomes (15.38), plant height (3.25mm), width of epidermis (0.19mm), and frequency of germination (66.63%), were observed in the UTC variety. The least frequency of germination (27.75%) and seedling height (1.06mm) was observed in Dan Syria under the condition of microgravity. Trichomes were absent in seedlings of Dan Syria under normal gravity. Seedlings of Dan Syria, UTC, and Teema subjected to disease stress revealed absence of stomata on exposure to microgravity conditions. Differences in effect of gravity conditions on morphological and anatomical features of the seedlings were significant (P≤0.05). The UTC tomato variety showed higher disease tolerance under microgravity stress, and could be considered for genetic studies aimed at selection of stress tolerance genes in the tomato variety, for enhanced yield and productivit

PRELIMINARY BOTANICAL ASSESSMENT OF PRODUCTION CHALLENGES OF CASHEW (ANACARDIUM OCCIDENTALE L.) IN LAFIA, NASARAWA STATE, NIGERIA

The aim of this study was to investigate the production and challenges of cashew farming in Lafia, Nigeria. The study area was divided into five zones. Fifty semi-structured questionnaires were administered to the farmers. The results showed that only males are engaged in cashew farming and slightly above 95% are married and just about 44% are aged between 21-40 y. Over 95% of farmers disclose that cashew production is seasonal; slightly above 73% disclose that diseases and pests are major challenges in cashew cultivation. Over 64% are of the opinion that these diseases and pests are responsible for yield reduction. Slightly above 52% disclose that yellow cashew is the most tasty and best for consumption. 52% of the farmers agree that 2017 is their best year of harvest because they were more involved in the management. 44% of farmers disclose that they do not apply chemicals and cultural practice in controlling diseases and pests, however majority agree that chemicals are useful in weed control. There was no agreement about the flowering and fruiting periods of cashew as 57% believe that cashew trees flower once, during the dry season and 65% disclosed that flowering occurs between January and March each year

ETHNOMEDICINAL ASSETS OF PLANTS COLLECTED FROM NASARAWA STATE, NORTH CENTRAL NIGERIA

An ethno-medicinal survey of plants used in treating various diseases and ailments was carried out in the study area of Nasarawa State, North Central Nigeria to obtain information on their uses and potentials. The ethnomedicinal survey was administered through structured questionnaires among local inhabitants from areas with high plant density and diversity within the various Local Government Areas of the State. A total of 82 (Eighty two) plant species belonging to 43 (Forty Three) families were found to be useful in treatment of various ailments such as diabetes, measles, fever, asthma, jaundice, pneumonia, sexually transmitted diseases(STDs),aches, diarrhea, cough, arthritis, yellow fever, typhoid, erectile dysfunction and excessive bleeding. Different parts of the plant such as the roots, leaves and stems are used in preparing herbal remedies which could be from dry or freshly collected plants. The main methods of preparation are decoction or infusion, while in some cases the plant parts used are consumed directly. Residents in the study areas find the herbal remedy cheaper and more accessible and claimed that there are no side effects compared to orthodox medicine. This study has confirmed the need towards the conscious conservation of plant genetic resources in order to ensure sustained access to these ethno-medicinal plant material

GROWTH AND ANATOMICAL RESPONSES OF TOMATO (LYCOPERSICON ESCULENTUM ) UNDER MICROGRAVITY AND NORMAL GRAVITY CONDITIONS

Microgravity is known to be a major abiotic stress in space which affects plants depending on the duration ofexposure. In this research, tomato seeds were exposed to long hours of simulated microgravity condition usinga one-axis clinostat. The seeds were sown on a 1.5% combination of plant nutrient and agar-agar solidifiedmedium in three Petri dishes. One of the Petri dishes was mounted on the clinostat and allowed to rotate atthe speed of 20 rpm for 72 hours while the others were subjected to the normal gravity vector. The anatomicalsections of both clinorotated and normal gravity plants were made after 72 hours and observed using a Phasecontrast digital microscope. The percentage germination as well as the growth rate of the normal gravity seeds was higher than the clinorotated treatments. The orientation of the clinorotated roots during germination were in different directions unlike the normal gravity which all germinated towards the direction of gravity vector. The clinostat was able to switch off gravistimulation as distinct cellular arrangement was observed for the tomato plants under normal gravity condition unlike those of the clinorotated treatment. The results revealed that the thickness of the epidermis and cortex of the roots of normal gravity are higher than those of clinorotated. This suggests that under long-term microgravity exposure, plants can acclimatize to the stress by changing their internal cellular features such as reduction in the thickness of cells and rate of cell proliferation

SOME ETHNOBOTANICAL USES OF PLANT RESOURCES IN NASARAWA STATE, NIGERIA

A study was carried out to evaluate the ethnobotanical uses of plant resources in Nassarawa State, Nigeria. A total of 80 plants belonging to 37 families were surveyed through oral interviews of local inhabitants from different locations in the State, who use various plant materials for their livelihood. Uses ranged from Ornamental, food, forage, timber and construction, pest control, and textile. Plants belonging to the families Poaceae and Caesalpinniaceae were mostly used for food (9.76% respectively), Poaceae(42.85%) for forage, Combretaceae, Poaceae and Moraceae (18.18% respectively) for timber, building constructions and fuelwood. Only members of the family Lamiaceae and Malvaceae were used for pest control and textile purposes respectively. Majority of plant use in the study area was for food (51.25%) followed by forage (17.15%). The genus Ficus had the highest number of ethnobotanical uses with four applications, followed by Terminalia and Ceibaboth having three applications each. The rich biodiversity of ethnobotanical significance in the study area needs to be adequately conserved in order to forestall over exploitation and extinction of economically important plant families which is the main source of economy to the inhabitant