The performance evaluation of a cassava pelletizer

This paper reports on the development and performance evaluation of a machine for cottage level production of pellets from cassava mash. Cassava flour was produced by peeling, grating and drying freshly harvested cassava tubers. Experiments were conducted to determine the physical properties, such as moisture content, particle size distribution and bulk density and the chemical composition of the flour. The flour was mixed with water at different blend ratios to form cassava mash of different moisture contents. A cassava pelletizer was then developed incorporating relevant properties of the flour. The pelletizer consists of a barreled screw auger, which compresses cassava mash against a perforated end plate, through which the pellets are extruded. The barrel is encased in a co-axial counter flow heat exchanger to provide cooling for the system. The performance of the pelletizer was evaluated in terms of the density, durability, crushing strength and cyanide content of the pellets, and the throughput of the machine, against the moisture content of the mash (18, 20 and 22 % w.b.), die size (4, 6 and 8 mm) and the auger speed (90, 100 and 120 rpm). Test results showed that the bulk density and the durability of pellets decreased while the moisture content increased significantly (p<0.05) and separately with increasing die size and moisture content of cassava mash. The pellets with the best quality attributes were obtained from cassava mash at 18% moisture content (w.b.) extruded through the 4 mm die at 90 rpm and a maximum throughput of 54 kg/hr. The pellets exhibited a bulk density of 635 kg/m3 , 15% moisture content (w.b.) crushing strength of 34.24 MPa and a high durability (85.7%). The machine, thus, provides a significant leverage in the utilization of cassava as pelletized animal feed

Design, fabrication and testing of a cassava pelletizer

This paper reports on the design of fabrication and testing of a machine for cottage level production of pellets from cassava mash. The pelletizer consists of a barreled screw auger which compresses cassava mash against perforated end plate, through which the pellets are pelletized. The result derived from the calculated design parameters (shaft diameter, tensile stress, torque, screw length, volumetric capacity mass flow rate and power rating) were used for the fabrication. The testing of the pelletizer was determined in terms of throughput of the machine, against the moisture content of the mash (18, 20 and 22% wb), die size (4, 6 and 8 mm) and the auger speed (90, 100 and 120 rpm). Test results showed that the pellets with the best quality attributes were obtained from cassava mash at 18% moisture content (wb) through the 4 mm die at 90 rpm and a maximum throughput of 54 kg/h

ECONOMIC ANALYSIS OF BUSHMEAT TRADE IN ABEOKUTA, OGUN STATE

This paper examines bushmeat trade in Abeokuta comprising of Abeokuta north and south LG areas of Ogun State. Forty-five (45) respondents were accidentally selected across the two local government areas. The respondents were involved in bushmeat trade at three different levels. There were hunters (31%), ethno-medicine sellers (49%) and bushmeat sellers (20%). The result of the study revealed that majority (69%) of the traders were female. Also, 87% of the respondents had poor education. Therefore respondents could not keep record of their transactions, but from qualitative and quantitative analysis of the profitability of the business, the trade may be described as profitable (89%). An estimate of average annual profit of the trade in the study area was N453,004.  Other benefit though insignificant is that of protein supplement of the family (8%) derived from the trade. Major constraint of the business is the seasonal fluctuation of supply (85%) which affects income of respondents. However, a total of  11 common species of wild animals were traded, therefore it is recommended that conservation policy in terms of educational programme that target hunters and sellers, in order to sensitize them on the danger of indiscriminate harvesting of the animals must be put in place along with improved domestication effort.Â

ECONOMIC CONTRIBUTION OF WILDLIFE TO BUSHMEAT MARKETS IN IBADAN, OYO STATE

This paper examined the economic contribution of wild animals to bushmeat trade in Ibadan, Oyo State, Nigeria. Five prominent bush meat markets in Ibadan and its suburb were used for the study. The selection was based on the high intensity of bush meat marketing operations identified with the markets. All sellers in each market visited were interviewed which sum up to forty four respondents. Data were collected using structured questionnaire. Budgetary analysis was done to calculate costs and return of the bushmeat sellers. Income on mammals had the highest (₦5,755,600) per annum followed by the income on birds (₦858,000) per annum and reptiles (₦182,000). In the same pattern, percentage contribution indicates that mammals contributed 84% of the total income, while wild birds contributed 12% of the total income and reptile 3%. The net profit realized from the sales of mammals was ₦4,979,000 and ₦180,900 for wild birds. Cost and return analysis showed that sale of bushmeat is a profitable venture. In addition, mammals contributed more to the economy of the market than other two classes of animal found in the bushmeat market

Effect of optical defocus on colour perception

Daily experience shows that colour  of a very distant object cannot be accurately determined.  It is assumed that visual acuity (VA) loss is one of the factors at play in this case.  The effects of reduced VA as a result of refractive error or optical defocus on colour vision have not been examined.  Such study will dictate the need or otherwise for optical correction before assessment of colour vision.  The purpose of this study therefore, was to investigate the effects of optical defocus on colour vision in individuals with normal colour vision.  Twenty nine young adult subjects (11 male and 18 females) were included in this study. Their ages ranged from 11 to 29 years with a mean of 22.1 ± 3.4 years.  All subjects had VA of 6/6 or better and normal colour vision.  The colour vision was evaluated with the Farnsworth panel D-15 (desaturated). Each subject was optically defocused to VA of 6/24, 6/60 and 1/60(6/360) at 6 meters respectively and colour vision was assessed at each reduced VA.  At VA of 6/24, colour vision was not affected in all subjects. When the VA was reduced to 6/60, however, 15 (51%) of the subjects failed the colour vision test. When the VA was further reduced to 1/60 by optical defocus, 24 (83%) of the subjects failed the colour vision test.  It was concluded that optical defocus and reduced VA can adversely affect colour vision test findings. While VA reduction to 6/24 may not affect the colour vision results, VA of 6/60 can.  It is therefore, recommended that in clinical colour vision  testing and colour vision screening, VA should first be assessed andcompensated, especially if uncorrected VA is 6/24 or worse

A review of the role of oxidative stress in the pathogenesis of eye diseases

Free radicals, referred to as oxidants are molecules in the body with unpaired electrons, hence are unstable and ready to bond with other molecules with unpaired electrons.  They include Reactive Oxygen Species (ROS) such as superoxide anion radicals (·O¯), hydrogen peroxide (H202), and hydroxyl free radicals (·OH).  Endogenous sources of ROS include metabolic and other organic processes, while exogenous sources include ultraviolet radiation and environmental toxins such as smoke.  Antioxidants (oxidant scavengers) such as ascorbate, alpha-tocopherol and glutathione as well as various enzymatic compounds such as superoxide dismutase (SOD), catalase and glutathione reductase are also present in the body and in manyfoods or food supplements.  An imbalance between oxidants and antioxidants in favour of oxidantsis termed oxidative stress and can lead to cell or tissue damage and aging. Oxidative stress has been implicated in the pathogenesis of many serious systemic diseases such as diabetes, cancer and neurological disorders.  Also, laboratory and epidemiological studies have implicated oxidative stress in the pathogenesis of the majority of common serious eye diseases such as cataract, primary open angle glaucoma and age-related macular degeneration. In this article, we reviewed the current information on the roles of oxidative stress in the pathogenesis of various eye diseases and the probable roles of antioxidants.  Eye care practitioners will find this article useful as it provides information on the pathogenesis of common eye diseases. (S Afr Optom 2011 70(4) 182-190

Assessment of Tree Species Diversity, Family Composition and Diameter Size Class of Tree Species in Igbo-Olua Sacred Groove, Ondo State, Nigeria

This study was carried out to assess the tree species diversity, family composition and diameter size distribution of the tree species in Igbo-Olua sacred groove, Ondo state, Nigeria using appropriate standard techniques. A total of 34 tree species distributed in 23 families were recorded.&nbsp; Sterculiaceae family (66) had the highest number of individual stem per ha while Moraceae family had the highest number in terms of tree species per hectare (7). The distribution of the diameter structure is typical of the natural forest type with high number of tree species in the smaller size classes or interval (12.5) and the number of tree species decreases with increasing size class or interval. Diversity measures obtained included Shannon-Weiner index (3.09), Evenness (0.64) and Margalef index (6.36). Awakening the consciousness of people towards the protection of sacred groves has practical implications on their survival. Hence government and other allied institutions should gear efforts towards grove conservation

Eye protection practices and symptoms among welders in the Limpopo Province of South Africa+

Welding is associated with several ocular and systemic hazards especially where adequate protective measures are not taken.  The purpose of this project was to study the eye protection practices and symptoms among welders in the Capricorn District of Limpopo Province, South Africa. Questionnaires designed to investigate eye protection practices and symptoms experienced were completed byone hundred and fifty (150) welders. The types of welding done were shielded metal arc (84%), oxyacetylene gas (4%) and silver brazing (12%). The number of years spent in the welding industry ranged from one to 10 years with a mean of 5 ± 3.1 years and the number of hours of welding per day ranged from one to 10 hours with a mean of 6 ± 2.1 hours. A large percentage of the welders (89%) reported wearing protective devices when welding and the most common protective devices used by the welders were: helmets (57%), goggles(22%), and face shields (15%). Six percent used inefficient protective devices such as sunglasses.   Sixty one percent reported occasional exposure to welding flashes when not wearing any eye protection. Welding-related eye symptoms reported included foreign body sensation (18%), persistent after-images (31%), and watery eyes (50%).  Al- though the majority of the welders wore protective devices while welding, a few did not always use such devices while others used sunglasses for protection.  Moreover, many of the welders were occasionally, and only a few were always, exposed to welding flashes when protective devices were not used. Therefore, we concluded that eye protectionpractices amongst the welders appeared to be inadequate to avoid hazards associated with welding.  It is recommended that an eye protection educational campaign for welders should form part of the SouthAfrican Government’s workplace safety program

Perceptions and opinions of graduating South African optometry students on the proposed community service

Community service (CS) was introduced inSouth Africa in an attempt to address the shortageand maldistribution of health care professionalswithin the public sector. The Professional Board forOptometry and Dispensing Opticians (PBODO)has approved legislation for the introductionof CS for graduating optometry students. This study examined the perceptions and opinionsof graduating optometry students regarding the proposed CS. A mixed-method design(questionnaires and interviews) was used. Bothapproaches yielded similar results. The quantitativecomponent included 119 participants, aged between 20 and 35 years (mean age and standard deviation;22.8 ± 2.3 years). There were 43.2% Blacks, 28.5%Whites, 19.1% Indians and 9.2% Coloureds. The qualitative part included fourteen participantsfrom the Optometry Department of the University of KwaZulu-Natal. The major themes emergingfrom the questions concerning the participants’ perceived advantages and benefits of CS were (i) it would improve the eye care service delivery to disadvantaged communities; (ii) it would improve the technical and clinical skills of the graduating optometrists and (iii) it would enhance their confidence, personal and social skills. Some of the perceived drawbacks cited by the participants about such service included poor remuneration and concerns about personal safety, transport and accommodation. The findings of this study suggest that graduating optometry students acknowledge the importance of CS in improving access of many South Africans to quality eye care. In order to maximise the full benefits of CS, all stakeholders need to address the highlighted concerns of the participants. (S Afr Optom 2013 72(1) 11-18

Awareness of the phototoxic effects of sunlight among South African university students

Due tothe depletion of the atmospheric ozone, there is currently a great concern for the phototoxic effects of sunlight on humans worldwide. The purpose of this study was to evaluate the awareness of the phototoxic effects of sunlight among a sample of South African university students.  A questionnaire on awareness of the adverse effects of excessive exposure to sunlight was completed by the participants and findings were analyzed. Ages of the participants (n=1832) ranged from 17 to 55 years (mean = 21.03 ± 3.44) and there were 43.7% males and 56.3% females.  Many, (73.9%) agreed that excessive exposure to the sun is harmful to health, but only 56.9% could adequately explain how it is harmful to health.  Many, (68.2%) agreed that fair-skinned individuals are more likely to be affected by the sun than dark-skinned ones.  Only 52% reported that childhood exposure to sunlight is more dangerous than adulthood exposure. A few (32.9%) agreed that short term intensive exposure was more dangerous than chronic regular moderate exposures.  Although 72.3% had heard about ultraviolet (UV) radiation, only 47.1% had heard of cataracts and fewer (25.7%) agreed that cataracts can be caused by UVR exposure.  A few (28.7%) had heard of macular degeneration, but only 17.6% agreed that it can be caused by UVR.  Although awareness was good in certain aspects, it was poor in others; suggesting the need for an awareness campaign among South Africans. It is recommended that the awareness campaign should include avoidance of excessive exposure and the use of appropriate protective devices. (S Afr Optom 2010 69(3) 146-151