In this contribution, authors present a review on the state-of-the-art in the utilization of industrial and agricultural waste materials for the development of metal–matrix composites (MMCs), providing, through the judicious analysis of an ample and varied references source – from the oldest to the newest ones – an insight into the challenges and opportunities for the exploitation to their full potential. In addition to its topicality, the novelty of this contribution lies in the presentation of key statistical, technical, and property-related information of a comprehensive variety of waste materials classed into two main groups, namely, fly ash reinforced MMCs and MMCs derived from other waste materials. Although fly ash has been exploited in a broad range of applications, the attention paid for its use in the development of MMCs seems to be insufficient. A purposely designed chart helped to pinpoint the more demanding and profitable applications of fly ash, and establish strategic opportunity ar...

Development of metal-matrix composites from industrial/agricultural waste materials and their derivatives

Indigenous and traditional foods crops (ITFCs) have multiple uses within society, and most notably have an important role to play in the attempt to diversify the food in order to enhance food and nutrition security. However, research suggests that the benefits and value of indigenous foods within the South African and the African context have not been fully understood and synthesized. Their potential value to the African food system could be enhanced if their benefits were explored more comprehensively. This synthesis presents a literature review relating to underutilized indigenous crop species and foods in Africa. It organizes the findings into four main contributions, nutritional, environmental, economic, and social-cultural, in line with key themes of a sustainable food system framework. It also goes on to unpack the benefits and challenges associated with ITFCs under these themes. A major obstacle is that people are not valuing indigenous foods and the potential benefit that can be derived from using them is thus neglected. Furthermore, knowledge is being lost from one generation to the next, with potentially dire implications for long-term sustainable food security. The results show the need to recognize and enable indigenous foods as a key resource in ensuring healthy food systems in the African continent.

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A Review of Indigenous Food Crops in Africa and the Implications for more Sustainable and Healthy Food Systems

Kaolin-supported ZnO nanoparticle catalysts in self-sensitized tetracycline photodegradation: Zero-point charge and pH effects

Nypa fruticans Wurmb. is one of the important underutilized fruit of Malaysia, which lacks scientific attention. Total phenolics, flavonoid content, and antioxidant capacities from endosperm extracts of Nypa fruticans (unripe and ripe fruits) were evaluated. Endosperm extract of unripe fruits (EEU) exhibited the highest phenolics ( mg GAE/g), flavonoid content ( RE/g), and antioxidant capacity. Free radical scavenging capacity of EEU as assessed by 2--azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radicals showed inhibitory activity of % and %, respectively. Beta carotene bleaching coefficient of EEU was higher (), when compared to endosperm extract of ripe fruits (). Additionally, EEU exhibited high antioxidant capacity by phosphomolybdenum method and ferric reducing antioxidant power values. Eight phenolic compounds from Nypa fruticans endosperm extracts were identified and quantified by ultra-high-performance liquid chromatography. Chlorogenic acid, protocatechuic acid, and kaempferol were the major phenolic compounds. Thus this fruit could be used as a potential source of natural antioxidant.

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Phytochemicals and Antioxidant Capacity from Nypa fruticans Wurmb. Fruit.

In this study, tissues of five fish species prevalent in the Houjing River were analyzed for heavy metal concentrations. Results show concentrations of such metals to be much higher than internationally recommended standard limits (as determined by the WHO and FAO) and other similar studies. Heavy metal contamination of fish in the Houjing River is hence significant. High hazard and carcinogenic risk related to the Houjing River's fish was proven based on target hazard quotient (THQ) and target cancer risk (TR) estimations. In fact, four of the five species studied present THQ levels higher than 1, and seven TRs of zinc (Zn) and arsenic (As) are higher than 10-4. Despite lower estimated daily intake (EDI) of fish in the area (per recommended daily allowance guidelines), possible heavy metal bioaccumulations in fish stock pose a high health risk for human consumption. From our analyses, the highest bioaccumulation factor (BAF) estimated above 1000 was of Zn. Among the fish species studied, Oreochromis niloticus possesses the ability to accumulate copper (Cu) and Zn dramatically. Pearson's correlation matrix showed a positive correlation between Cu and As, attributed to multiple industrial activities along the river. Hierarchical cluster analysis of results based on sampling stations exhibits three clusters and may be linked to the type of industrial activities specific to that area. More intensive study is needed in order to further determine the toxic metals in fish. Reporting of contaminant levels must be compared with optimal health criteria guidelines. Our study, while showing the severity of heavy metal contamination in fish stock, calls for urgent, sustained, and targeted actions by both governmental authorities and the local scientific community-to help prevent and mitigate the situation and ensure the physical well-being of local inhabitants.

Bioaccumulation and potential sources of heavy metal contamination in fish species in Taiwan: assessment and possible human health implications.

Two sets of samples of commercially important fish species Oreochromis niloticus of size 29 cm and 20 cm respectively were purchased from the Henshaw town beach market in Calabar, Calabar South Local Government Area of Cross River State, Nigeria in October 2007. The concentrations of five heavy metals (Pb, Zn, Cd, As and Hg) in their bones, gills, livers and muscles were determined using flame atomic absorption spectrophotometer. The result showed the heavy metal concentrations in the 29 cm size samples to be Pb (0.069 ppm) Cd (0.019 ppm) and Zn (0.103 ppm) in the bones. Pb (0.173 ppm) Cd (0.049 ppm) and Zn (0.257 ppm) in the livers. Pb (0.053 ppm) Cd (0.015 ppm) Zn (0.079 ppm) in the muscles Pb (0.133 ppm), Cd (0.038 ppm) and Zn (0.198 ppm) in gills. While the 20 cm size samples had Pb (0.067 ppm) Cd (0.019 ppm) and Zn (0.100 ppm) in bones. Pb (0.067 ppm) Cd (0.019 ppm) and Zn (0.099 ppm) in livers. Pb (0.062 ppm) Cd (0.017 ppm) and Zn (0.095 ppm) in muscles and Pb (0.153 ppm) Cd (0.044 ppm) and Zn (0.227 ppm) in gills. Arsenic and mercury were not detected in any of the samples. The result revealed the distribution of the heavy metal in both 29 cm and 20 cm size samples to follow the order Zn> Pb> Cd while the distribution of the heavy metals in the investigated parts (organs) is shown to follow the order livers > gills > bones > muscles for the 29 cm size samples. And Gills > Livers = bones > muscles in the 20 cm size samples. The result also revealed that the 29 cm size samples had higher concentrations of the heavy metals than the 20 cm size samples. The result also showed that the muscle of Tilapia is safer to consumed than the other parts investigated as it has been shown to contain the least concentrations of the heavy metals determined. This reveals the adverse health effect the people in the study area could be exposed to by the consumption of liver, gills and bones of Tilapia which have high levels of these heavy metals.

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Distribution of heavy metals in bones, gills, livers and muscles of (tilapia) Oreochromis niloticus from Henshaw town beach market in Calabar Nigeria.

The effects of culinary practices such as boiling, frying, and grilling on the proximate compositions and concentrations of metals (Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg) in commonly consumed fish species from the Nigerian coastal waters were investigated. The selected fish species were Polydactylus quadratifilis, Chrysicthys nigrodigitatus and Cynoglossus senegalensis. The culinary practices lead to increased protein, fat, and ash contents and decreased moisture contents of these fish species. The culinary practices resulted significant increase in the concentrations of most of the studied metals and decrease in the concentrations of Fe, Cr, and Pb in some fish types. The concentrations and estimated dietary intakes of Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg from consumption of the processed fish were within their statutory safe limits. The individual metal target hazard quotient (THQ) values and the total THQs were less than 1 which indicates that no health risks would arise from the long-term consumption of these fish species.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/fsn3.102

Effects of processing on the proximate and metal contents in three fish species from Nigerian coastal waters.

3 Abstract: The African bread fruit is produced by Treculia, a wild tropical evergreen tree and has immense potential as a nutritional source for man. We evaluated its chemical and nutritional properties as a first step in realizing its food value. The seed (Dry Mass (DM) basis) contained 8% moisture, 12.5% crude protein, 4.2% fat 2.3% ash 1.6% fibre and 73% carbohydrate. The carbohydrate and protein contents in it were much higher than other parameters studied. Compositions of toxicants in seeds were quite low with levels (mg/100 g) of 0.06±0.12 for hydrocyanide 3.0±0.11 for oxalate and 0.76±0.01 for phytate. For mineral elements, the contents (mg/100 gDM) were 587±0.2 for potassium (K), 186±0.2 for Magnesium (Mg) and 850±0.02 for zinc (Zn). The sodium (Na), Calcium (Ca), iron (Fe) and Copper (Cu) contents were negligible. Results of phytochemical screening of the extract showed, that it contained appreciable amounts of flavonoid , polyphenols, anthraquinones, saponins and cardiac glycosides. These secondary metabolites are known to have microbial activity as well as other physiological activity.

Profile of the African Bread Fruit (Treculia africana)

2 Abstract: The nutritional value, mineral element compositions and phytochemical screening of Nypa fruiticans (mangrove swamps) were investigated. Proximate analyses of the husk showed that it contained moisture (65.14±.0.04% DM), fat (1.5±0.13% DM), crude protein (2.00±0.64% DM), fibre (2.47±0.09% DM), ash (4.20±0.14% DM), carbohydrate (24.63±0.17% DM) while the seeds contained moisture (41.96±0.28% DM), fat (0.94±0.01% DM), crude protein (1.27±0.01% DM), fibre (2.50±0.19% DM), ash (2.70±0.11% DM) and carbohydrate (51.0±1.71% DM). The moisture and carbohydrate contents revealed increased levels in both husk and seeds than other proximate parameters. The toxicant compositions of the husk revealed that hydro cyanide, oxalate and phytate contents were 0.63±0.02, 6.50±0.025 and 4.03±0.09 mg/100g DM respectively while the seeds revealed 0.08±0.01, 9.90±0.08 and 8.50±0.64mg/100g DM respectively. The hydro cyanide, oxalate and phytate contents were quite low in both seeds and husk. Mineral elements concentrations revealed potassium contents of 147.28±0.65mg /100g DM for the husk while the seeds showed 128.52±0.6mg/100g DM. The magnesium, sodium, iron, calcium, copper and zinc contents were virtually low in both seeds and husk of Nypa fruiticans. The vitamin A contents of the seeds and husk show that it contained 30.50±0.64 and 8.00±0.21mg/100g DM respectively.

Chemical Profile of Nypa fruiticans from Cross River Estuary, South Eastern Nigeria

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V. N. Osabor

Papers

Distribution of heavy metals in bones, gills, livers and muscles of (tilapia) Oreochromis niloticus from Henshaw town beach market in Calabar Nigeria.

Effects of processing on the proximate and metal contents in three fish species from Nigerian coastal waters.

Profile of the African Bread Fruit (Treculia africana)

Chemical Profile of Nypa fruiticans from Cross River Estuary, South Eastern Nigeria

A comparative evaluation of heavy metals in commercial wheat flours sold in Calabar-Nigeria.