Performance of Different Bunch Cover Materials to Improve Quality of Cavendish Banana Cultivated During Winter and Summer in Thailand

Performance of different cover materials on improving Cavendish banana quality was examined during winter and summer. The banana bunch was covered with a thin nonwoven innermost layer, followed by cover materials arranged from inner to outer as follows. (1) Control (commercial cover), paper/polystyrene sheet (PS)/non-perforated blue polyethylene (NPPE), (2) nonwoven (NW)/NPPE, (3) waterproof nonwoven (WPNW), (4) aluminum foil (ALF), and (5) WPNW + ALF. For the summer trial, control without PS layer was applied. Material properties including thickness, light transmissivity and heat energy (Qx) were evaluated. Results showed that Qx values transferred through PS sheet, NW, WPNW and ALF were not significantly different. ALF exhibited the lowest light transmissivity, associated with the highest fruit lightness (L*) and lowest fruit weight. For the winter trial, all cover materials exhibited chilling injury on fruit caused by temperatures below 10 °C. For the summer trial, five treatments prevented sunburn defect. Under field air temperature of 47.5 °C, ALF exhibited the lowest temperature (31.6 °C). All cover materials reduced hand and fruit sizes, whereas WPNW resulted in an increase in total soluble solids and prevented fading of the green peel color. Results suggested that WPNW, with reduced layers as environmentally friendly and reusable materials, had potential as a cover material to improve the quality of Cavendish banana.

Influence of feedstock type and particle size on efficiency of biochar in improving tensile crack resistance and shear strength in lean clayey soil

The development of tensile stress can cause desiccation cracks, further increasing infiltration and inducing instability in green infrastructure (slopes and landfill liners). Recent research has promoted the use of biochar (i.e., stable carbon with a life period of more than 500 years) as an eco-friendly material that can provide simultaneous benefits in reducing tensile stresses and crack development, aiming to enhance landfill cover longevity. However, there is a lack of guidelines and criteria for selecting biochar (feedstock type and particle size) as landfill cover material. This study aims to investigate the effects of biochar particle size and feedstock type on cracking of soil. Two contrasting feedstock types (i.e., pig manure-based and wood-based) have been selected for amendment on lean clay soil. Laboratory experiments were conducted to monitor the cracks. The results show that wood biochar (WB) is more efficient in crack reduction than pig manure biochar (PMB). Moreover, it has been observed that fine-grained biochar is more suspectable to cracks formation regardless of biochar type. The cohesion and internal friction angle of biochar are dependent on the surface morphology of biochar. WB has more angularity and sharp edges, which can increase interlocking in soil, thereby enhancing shear resistance and, hence, soil stability. The comprehensive study can help narrow down the selectivity of biochar and its specifications to mitigate cracks and enhance the strength of landfill cover.

Passive Heating and Cooling of Photovoltaic Greenhouses Including Thermochromic Materials

The integration of photovoltaic technologies into greenhouse envelopes appears to be an innovative and environmentally-friendly way to supply their various energy demands. However, the effect on the inner growing conditions, especially on the temperature, must be assessed in order to effectively implement this solution. In this study, experimental temperature data were obtained over two years for four structures built with different photovoltaic technologies (mono-crystalline silicon, amorphous silicon, cadmium telluride, and an organic polymeric technology) and fitted to a thermal model in order to provide a comprehensive analysis of their potential utilization as a cover material in greenhouses. Additionally, the thermal effect of color in structures composed of several common construction materials (brick, wood, plasterboard and glass) was quantified and modelled, supplementing the thermal analysis of passive solutions for this application. In all cases, inner and ambient temperature differences of up to +20 °C, created by a passive heating effect during the day, and −5 °C, created by a passive cooling effect during the night, have been observed, suggesting the use of the photovoltaic modules with different degrees of structure coverage, complemented with the color tuning of the modules themselves as passive methods to control the temperature and light spectrum of greenhouses.

Guide to Africa Bibliography

This bibliography records publications on Africa of interest to students of Africa, principally in the social and environmental sciences, development studies, humanities and arts. Some items from the medical, biological and natural sciences are included. The criterion used is potential relevance to a reader from a social sciences/arts background. The whole continent and associated islands are covered, with selective coverage of the diaspora. This volume aims to cover material published in 2020 together with items from earlier years not previously listed. The editor is always very glad to hear of any items omitted so that they may be included in future volumes. He would be particularly pleased to receive notification of new periodicals, print or online. African government publications and works of creative literature are not normally listed.

Commodity Frontiers 1, Fall 2020 Cover Material

Cover material, table of contents, mission statement.