Functionality Enhancement of Composite Cassava Flour in the Production of Maize Tuwo (A Non-fermented Maize-Based Food Dumpling)

The study was focused on the evaluation of textural and sensory quality enhancing functionality of cassava flour in the production of maize tuwo (a non-fermented maize-based food dumpling). The cassava flour was added to maize flour at the level of 5%, 10%, 15%, 20%, 25% and 30% (w/w), respectively. The bulk density and water holding capacity of maize/cassava flour mixes ranged from 0.77–0.83 g/cm³ and 1.91–2.05 g/g, respectively, while those of 100% maize flour were 0.84 g/cm³ and 2.09 g/g, respectively. There were variations in the pasting properties of maize/cassava flour mixes including the pasting temperature (75.4–78.8°C), peak viscosity (112.1–170.0 RVU), breakdown viscosity (38.4–53.7 RVU) and final viscosity (132.1–142.2 RVU), while those of 100% maize flour were 74.6°C, 108.1 RVU, 38.1 RVU and 148.3 RVU, respectively. The colour characteristics of tuwo prepared from maize/cassava flour mixes showed an increase in the colour lightness, L*-value (68.6–71.8) and chroma, C-value (9.4–11.4) while tuwo from 100% maize flour gave 67.7 and 9.1, respectively. The cohesiveness indexes (15.4–24.2%) of tuwo from maize/cassava flour mixes increased with an increase in the quantity of cassava flour in the mix while that from 100% maize flour was 15.2%. The softness indexes (17.5–18.4°mm) of tuwo from the mixes were also higher than that from 100% maize flour (17.4°mm). The sensory quality rating of tuwo from maize/cassava flour mixes showed that tuwo from 25% cassava flour inclusion was the highest in terms of texture (hand-mouldability), taste and overall acceptability while that from 30% cassava flour inclusion was the highest in terms of colour.     

Prebiotic effects of cassava fibre as an ingredient in cracker-like products

Cassava fibre, a waste product formed in starch production, was incorporated into wheat to give composite flours at ratios of 80/20, 70/30, 60/40 and 50/50, respectively. A cracker-like biscuit was produced from the preferred ratios (60/40 and 50/50). The effects of these on diets as a prebiotic were evaluated in a rat assay. Determinations of the proximate composition and haematological parameters were made as well as microbiological analysis. The protein content of the cracker-like product based on the 50/50 and 60/40 (fibre/wheat flour) ratios were 15.0% and 10.0%, respectively. Crude fibre ranged from 14.1-17.1% while ash ranged from 3.0 and 5.0%. Low cholesterol levels of 28.75 mg dL(-1) and 18.75 mg dL(-1) were recorded for the 50/50 and 60/40 composite ratios, respectively. The result of liver function test showed that the rats that were fed the fibre-based cracker product had an average value of 44.00 IU L(-1) of aspartate amino transferase (AST), which is lower than the 67.75 IU L(-1) recorded for the control. There was a significant increase in the packed cell volume (PCV) of the rats fed a fibre-based diet, relative to those fed "Ogi" (fermented maize). Haemoglobin was significantly higher in the control sample than all others, while no significant difference was observed in the white blood cell (WBC) count, with average of 11.75 mm(3). Data obtained from the faecal analysis showed that the rats fed with the composite ratios and other diets had an increased Lactobacillus count. However, by increasing the number of days that the rats were fed the fibre-based diet, the E. coli count in the rat faeces reduced significantly. The data obtained shows that cassava fibre-based crackers have good nutraceutic effects, with reduction in the E. coli count found in the rat faeces and healthy performances in terms of weight gain.     

Web‐Forming System Design Using CFD Modelling for Complex 3D Nonwoven Shell Structures

Summary: CFD modelling has been used to study the unique problem of airflow containing fibres around 3D porous media in nonwoven web forming systems. The related gas‐solid two‐phase flows were simulated using a commercial CFD package, FLUENT. Simulation results revealed that the uniformity of air velocities and fibre concentration around the moulds, particularly for complex‐shaped moulds, could be improved significantly by means of employing vertically oriented web forming system and moulds with controlled porosity. Experimental results indicated that the distribution of the area densities of the 3D nonwovens produced using polypropylene/polyester bi‐component fibre followed the same patterns of the airflow and fibre distributions simulated using the CFD model. The CFD model is a valuable tool for optimising the web forming systems and improving the uniformity of the 3D nonwovens.

Area density distribution of the 3D products produced using the vertical system.     

Observation of current reversal in the scanning tunneling spectra of fullerene-like WS2 nanoparticles

Current-voltage characteristics measured using STM on fullerene-like WS2 nanoparticles show zero-bias current and contain segments in which the tunneling current flows opposite to the applied bias voltage. In addition, negative differential conductance peaks emerge in these reversed current segments, and the characteristics are hysteretic with respect to the change in the voltage sweep direction. Such unusual features resemble those appearing in cyclic voltammograms, but are uniquely observed here in tunneling spectra measured in vacuum, as well as in ambient and dry atmosphere conditions. This behavior is attributed to tunneling-driven electrochemical processes.     

A system approach to the environmental analysis of industrial buildings

The construction sector plays a major role in the development of society. It wields enormous influence over economic activity, employment and growth rates. However, it also has a substantial impact on the natural environment, the effects of which are evident across the world. Over recent decades, pioneering initiatives have proposed environmentally friendly buildings and sustainable construction has centred on residential and office buildings. Nevertheless, further consideration still needs to be given to sustainability in many areas of industrial construction. Accordingly, an Integrated Value Model for Sustainable Assessment (MIVES) is presented in this article that applies a set of six study scopes to define the sustainability criteria of industrial buildings. The system uses a requirements tree to quantify sustainability at various hierarchical levels, in order to assess the behaviour of industrial buildings and compliance with the criteria. Assignment of value functions to the sustainability criteria is then described in the context of a case study of a printing works, which demonstrates the effectiveness of this model at unifying both qualitative and quantitative indicators, in order to arrive at a specific “environmental sustainability index” for the industrial building.     

A model for determining the global solar radiation for Makurdi,Nigeria

An empirical model for determining the monthly average daily global solar radiation on a horizontal surface for Makurdi, Nigeria (Latitude 7°7′N and Longitude 8°6′E) was developed using the Angstrom–Page equation. The solar radiation (W/m²), hours of bright sunshine and cloudiness were measured hourly from 0600 H to 1800 H daily for 18 months. The constants ‘a’ and ‘b’ of the Angstrom linear type equation were determined by plotting the clearness index (H/H_o) against the possible sunshine hours (n_s/N) to obtain the line of best fit. The constant ‘a’ was obtained from the intercept of the line on the y-axis while the constant ‘b’ was obtained from the slope of the line. The developed model for determining the global horizontal solar radiation at the location was H = H_o [0.17 + 0.68(n/N)] with a coefficient of correlation of 0.78. The mean bias error and root mean square error that were used to test the performance of the constants were 0.17% and 1.22% respectively. The measured solar radiation was compared with the solar radiation predicted by the model and no significant difference was found between them using F-LSD at P ≤ 0.05.     

Small‐Scale Propellers Deliver Miniature Versions of Themselves

Small‐scale actuators and propellers have benefited from advances in materials and manufacturing to become more lifelike. Inspired by animal species, multi‐generational chemically powered artificial propellers that carry small versions of themselves and deliver them “on‐the‐fly” are described. The released replicas are capable of autonomous propulsion and propelling immediately after detachment. Release occurs without human involvement and relies solely on sacrificial layers separating the carriers and replicas. These layers are composed of transient natural polymers, which dissolve under the swimming conditions to release the confined replicas. Judicious selection of the responsive transient materials, layer thickness, and solution conditions (e.g., pH), leads to programmable delivery of the replicas. Finally, the ability of the same carrier propellers to carry and transport multiple generations of propellers and deliver them at predetermined times is demonstrated.     

Microbiological stability and general sensory acceptance of microfiltered skim milk with agave fructans of a high degree of polymerization added

Skim milk was microfiltered in a pilot system equipped with ceramic membranes that have a novel configuration in their active layer, for the production of microbiologically-stable milk. The linear velocity (LV), temperature (T), and transmembrane pressure (TMP) were studied to assess the effect on bacterial reduction and protein permeation in the microfiltration system. Statistical analysis showed significant effects (α = 0.05) of T on flux, LV on protein permeation, and all the three conditions on the logarithmic reduction of microorganisms. The optimal operational conditions in the system obtained by the surface response method were LV = 6 m/s, T = 30°C, and TMP = 1.5 bar. These operational conditions ensured high filtration performance and a logarithmic reduction of bacteria by 4.55 log and extension of the shelf life to 5 days during storage at 4°C, the microbiological stability of microfiltered milk was not affected by the addition of prebiotic agave fructans of a high degree of polymerization. The microfiltration allows microbiological stability, conservation of functional compounds, and preservation of organoleptic sensory properties of milk, for the production of healthy and innocuous fresh dairy products with higher shelf life.     

Parametric studies of mixed convective fluid flow around cylinders of different cross-sections

A numerical study of mixed convective heat transfer in a lid-driven square enclosure containing a hot elliptic cylinder is conducted. The impacts of the Grashof number $({10}^3\le \mathit{Gr}\le 10^6)$, Reynolds number $(1.0\le Re\le 100)$, cylinder tilt angle $(0^{°}\le \varphi \le {90}^{°})$, and aspect ratio $(1.0\le AR\le 3.0)$ have been examined for a fluid of $Pr$ of 0.71. The horizontal enclosure walls are insulated, while its vertical walls are restricted to a nonvarying temperature T_c, whereas a sinusoidal temperature of $T_h+∆T\sin (\pi x/L)$ is imposed on the wall of the elliptical cylinder. The governing equations are solved using COMSOL Multiphysics 5.6 software. The fluid dynamic and the heat transport profiles between the enclosure and the elliptical cylinder walls are represented by the stream function, isothermal contours, and average Nusselt number. Results established that for all the considered aspect ratios, the thermal heating range of ${10}^3\le \mathit{Gr}\le 10^4$ is predominantly a conduction mechanism. The critical position of the ellipse where the inclination effect becomes insignificant is determined by the Grashof number and aspect ratio when the Re = 100. The strength of vortices and cell numbers are significantly influenced by the aspect ratio, particularly when the $\mathit{Gr}=10^4$. When $AR=1.0$, the average heat transfer from the cylinder remains the same regardless of the cylinder's orientation. The impact of cylinder orientation on heat transfer from the cylinder wall is minimal for $1.5\le AR\le 2.0$. For AR values of $2.5\le AR\le 3.0$, increasing the inclination angle does not result in improved heat transfer. The influence of the increasing inclination angle on the right wall diminishes as the angle increases, except when the Grashof number is greater than 10⁵, where the rate of heat transfer is enhanced for inclination angles beyond 45°.