Performance of Thermal Insulation Covering Materials to Reduce Postharvest Losses in Okra

The efficiency of different thermal insulation covers in minimizing temperature fluctuations in cool chain management was investigated to reduce postharvest loss and maintain okra quality during storage and transportation. The four thermal insulation covering materials: (1) heat reflective sheet with thin nonwoven (HRS + TNNW), (2) heat reflective sheet with thick nonwoven (HRS + TKNW), (3) metalized Tyvek® (MTyvek) and (4) metalized foam sheet (MFS) were studied and compared with perforated linear low-density polyethylene (P-LLDPE) as the typical handing package for okra distribution alongside no covering as the control. The material properties, transpiration rate, vital heat, temperature profiles (air and pulp temperatures), relative humidity, mass loss and incidence of decay were determined throughout a simulated supply chain. Results exhibited that HRS + TNNW and HRS + TKNW covers had the lowest thermal heat energy (Qx) and moderate R-value. These two covers maintained low temperature fluctuation with the lowest rate of air and pulp temperature changes, reflecting in lowest mass loss and decay in okra. The HRS + TNNW cover yielded less decay (1%) in okra, compared to commercial covers; MTyvek (16%) and MFS (9%). Results showed that HRS + TNNW exhibited great potential as a thermal insulation cover to reduce postharvest loss in okra (5%) compared to typical handling (11–18%) and could be considered as alternative material to reduce the use of foam sheets in cool chain management distribution packaging of okra under ambient environment conditions.

In Vivo Pulp Temperature Changes During Class V Cavity Preparation and Resin Composite Restoration in Premolars

SUMMARY Objective: This in vivo study evaluated the influence of the sequence of all restorative steps during Class V preparation and restoration in human premolars on pulp temperature (PT). Methods and Materials: Intact premolars with orthodontic extraction indication of 13 volunteers received infiltrative anesthesia and isolation with rubber dam. An occlusal preparation was made with a high-speed diamond bur under air-water spray until the pulp was minimally exposed, then a thermocouple probe was inserted within the pulp. A deep, 2.0-mm depth Class V preparation was made using a high-speed diamond bur under air-water spray. Three restorative techniques were performed (n=7): Filtek Z250 placed in two increments (10-second exposure, shade:A2, 3M ESPE, St. Paul, MN, USA), Filtek Z350 XT (40-second exposure, shade:A3D, 3M ESPE) and Tetric N Ceram Bulk Fill (10-second exposure, shade:IVA, Ivoclar Vivadent, Schaan, Liechtenstein), both placed in a single layer. Bonding layer and resin composite were exposed to light from the same Polywave LCU (Bluephase 20i, Ivoclar Vivadent). The peak PT and the difference between peak PT and baseline (ΔT) values were subjected to two-way, repeated measures analysis of variance (ANOVA), followed by the Bonferroni post-hoc test (α=0.05). Results: Cavity preparation and etch & rinse procedures decreased the PT values (p<0.001). The 40-second exposure of Filtek Z350 caused the highest peak PT values (38.7±0.8°C) and the highest ΔT values (3.4±0.8°C), while Tetric N Ceram Bulk Fill showed the lowest values (−1.6±1.3°C; p=0.009). Conclusion: None of the evaluated procedures resulted in a PT rise near to values that could offer any risk of thermal damage to the pulp.

Application of Room Cooling and Thermal Insulation Materials to Maintain Quality of Okra during Storage and Transportation

A combination of room cooling and the use of thermal insulation materials to maintain okra quality under simulated storage and transportation was evaluated. Okra pods were packed in plastic baskets and either cooled at 18 °C or not cooled in a room for 2 h. After either room cooling or no cooling, the okra pods were covered with three different materials: (1) perforated linear low-density polyethylene (P-LLDPE), (2) two layers of heat-reflective sheet with thin nonwoven (HRS+TNNW), and (3) metalized foam sheet (MFS). Typical handling (TP) without cooling and covering with P-LLDPE was used as the control. The six treatments were conducted during simulated storage (18 °C for 48 h) and transportation (30 °C for 15 h). Results showed that MFS gave the best insulation properties (Qx and R-values), followed by HRS and TNNW. After room cooling, both HRS+TNNW and MFS materials delayed the time for pulp temperature to reach 18 °C (10 h), compared to P-LLDPE (2 h). TP presented the highest mass loss (17.8%) throughout simulated conditions, followed by cooling plus P-LLDPE (15.2%) and either of the thermal insulation materials with or without room cooling (3.6% to 5.2%), respectively. TP, cooling plus P-LLDPE, and no cooling plus MFS (44% to 56%) showed the highest percentage of decay, while cooling combined with both HRS+TNNW and MFS gave the lowest decay incidence (11–21%). Findings demonstrated that room cooling combined with HRS+TNNW had the highest efficiency for preserving cool temperature and reducing decay, compared to TP and room cooling plus MFS.

Postharvest Fumigation of Fresh Citrus with Cylinderized Phosphine to Control Bean Thrips (Thysanoptera: Thripidae)

Bean thrips (BT), Caliothrips fasciatus (Pergande), is a pest of concern to certain countries that import fresh citrus fruit from California, USA. A series of laboratory-scale exploratory fumigations with phosphine at 4.9 ± 0.3 °C (mean ± 2 SD; x¯±2s) were conducted to evaluate the postharvest control of adult BT. Models of the duration–mortality response predicted ca. 99% mortality of BT populations when headspace concentrations of phosphine, [PH3], are maintained at levels ≥0.4 g m−3 (250 ppmv (µL L−1)) and ≤1.5 g m−3 (1000 ppmv (µL L−1)) for 12 h, with the duration representing the lower bound of the 95% confidence level (CL). Confirmatory fumigations, each lasting 12 h, were then conducted using BT-infested sweet oranges, Citrus sinensis (L.), at pulp temperature (T) ≤ 5 °C to corroborate the exploratory results. Three formulations of cylinderized phosphine were used: 1.6% phosphine by volume in nitrogen, VAPORPH3OS®, and ECOFUME®, all applied at two levels, ca. 1.5 g m−3 (1000 ppmv (µL L−1)), as well as 0.5 g m−3 (300 ppmv (µL L−1)). Collectively, across the formulations, an applied dose of ca. 1.5 g m−3 (1000 ppmv (µL L−1)) resulted in 0 survivors from 38,993 (probit 8.60, 95% CL; probit 9, 72% CL) treated BT, while an applied dose of 0.5 g m−3 (300 ppmv (µL L−1)) resulted in 0 survivors from 31,204 (probit 8.56, 95% CL; probit 9, 70% CL) treated BT. Results were discussed in the context of commercial and operational features of quarantine and pre-shipment (QPS) uses of phosphine to treat fresh fruit and, specifically, the control of BT in fresh citrus exported from California, USA, to Australia.

Comparative Studies on Flotation Performance of Saturated Fatty Acids and Unsaturated Fatty Acids Separated from Hogwash Oil

Low flotation recovery, high pulp temperature, and large dosage of reagents are the typical disadvantages when using mixed fatty acids (MFA) prepared from hogwash oil for flotation directly. To determine the type of fatty acid that yields poor flotation performance, flotation performance and adsorption characteristics of saturated fatty acids (SFA) and unsaturated fatty acids (UFA) separated from the MFA were studied in our work. GC-MS, FT-IR, iodine value detection and melting point measurement showed that UFA contained –(CH=CH–CH2)n- groups and had much lower melting point. Quartz flotation tests were used to compare the flotation performance of UFA and SFA, which showed that UFA had excellent low-temperature floatability, and the flotation recovery of UFA was 35 percentage points higher than that of SFA at 20 °C and pH = 11.5. Zeta potential, FT-IR and XPS analysis indicated that UFA and SFA could adsorb onto the surface of activated quartz through chemisorption and hydrogen bonding. However, the adsorption of UFA was much stronger and more favorable; thus, the reason MFA have poor flotation performance was the presence of SFA.

Temperature Sequential Data Fusion Algorithm Based on Cluster Hierarchical Sensor Networks

The process of extracting gold by biological oxidation involves oxidizing the refractory high-sulfur and high-arsenic ore with the help of bacteria to decompose the wrapping material of gold to extract the gold. Therefore, maximizing the activity of bacteria will directly affect the efficiency of gold extraction, for which it is particularly important to maintain the pulp temperature in the oxidation tank at the optimal bacteria breeding temperature. However, gold mines are generally located in mountainous areas, and the large temperature difference between day and night in winter, coupled with the influence of wind and snow, creates variations in the temperature in the oxidation tank. The traditional temperature measurement method cannot fully reflect the temperature change of the oxidation tank. As a multi-field application method, sensor information fusion can effectively address the problem of pulp temperature measurement. First, we analyzed the heat transfer principle inside the oxidation tank, and designed the cluster hierarchical sensor network according to the spatial position of each oxidation tank and the environmental interference factors. The network structure is divided into three layers; the bottom of the sensor to collect pulp temperature data shows a spiral distribution in the inner wall of the oxidation tank. Each cluster head node sensor is used as an intermediate layer to complete local measurement fusion estimation. Finally, the fusion center is taken as the upper layer to realize the global state fusion estimation. Secondly, in the data processing of the bottom temperature sensor, the traditional unscented Kalman filter (UKF) algorithm is improved and the fading memory matrix is added to improve the identification of nonlinear modeling errors. The sequential observation fusion estimator (SOFE) algorithm is embedded in the measurement update to improve the performance of local measurement fusion. Finally, in the global state fusion estimation, the sequential analysis is combined with the inverse covariance intersection, and the sequential analysis and inverse covariance intersection-global state fusion estimation (SICI-GSFE) algorithm is proposed. Through calculation and simulation, the results show that the external interference can be reduced by combining all the temperature state estimations, and the accuracy of the best global temperature state estimation is improved.

The Role of Gangue Mineralogy on Flowsheet Development in Fluorite Processing

Fluorite, CaF2, is considered a strategically important mineral as it is a raw material for many strategic industries. Froth flotation is reported to be the most efficient and economically viable process for the production of an acid-grade product with a CaF2 content of at least 97%. Selective flotation of fluorite from gangue minerals, e.g., calcite and barite, is challenging because these minerals have similar physicochemical properties. This study employed batch flotation tests coupled with mineralogical analysis to design suitable customised flowsheets and efficiently optimised reagent regimes for optimum production of acid-grade fluorite concentrate from two different fluorite ores by the froth flotation process. The effect of pulp temperature on fluorite flotation was investigated in this study with the objective of lowering pulp temperatures in fluorite flotation. The results showed that an acid-grade CaF2 concentrate could be obtained from the flotation of both ores at ambient pulp temperatures. This eliminates the requirement for high-temperature pulp treatment, which would result in a significant reduction in thermal energy costs. This study showed that an understanding of gangue mineralogy is key to process optimisation for acid-grade CaF2 production. Although an acid-grade CaF2 concentrate could be produced from both ores, the flowsheets and reagent regimes were markedly different. For instance, the production of an acid-grade CaF2 product from a high quartz and calcite ore was achieved by employing a simple rougher–multiple cleaner flotation circuit using tannin and sodium silicate as calcite and quartz depressants, respectively. On the other hand, the production of an acid-grade CaF2 product from the flotation of the pyritic ore required a pre-sulphide flotation stage for upfront sulphur removal and the use of a sulphide depressant. Multiple stages of cleaning were required for improved selectivity in the flotation of both ores.

An Experimental Research on Cationic Reverse Flotation of Anshan-Type Iron Ores

The mineral processing technology of Anshan-type iron ores has been developed in a rapid speed in recent years, and the combined flowsheet at the core of anionic reverse flotation has become a mainstream in the beneficiation of Anshan-type iron ores in china. With the successful application of this combined flowsheet, some obvious problems are also emerging. Such as high requirement of pulp temperature, complex reagent system, high cost of reagent consumption and so on. In view of this,we have carried out an experimental study on the separation of Anshan type iron ore by cationic reverse flotation . A new collector (named KBD) which is mixed amines have been developed . On this basis, the actual mineral separation experiment is carried out in the laboratory.With KBD as the collector,and starch and sodium hexametaphoshate as the depressant, has resulted in an iron concentrate of 68.16% and recovery rate of 89.71%. The determination of the electrokinetic potential and the infra-red spectroscopic analysis show that KBD can effectively and priorly adsorbed to the surface of quartz, and has greatly change the elecrtokinetic potential of quartz.The interaction of the depressing agent has increased the differences of the floatabilities in quartz and hermitite and changed the surface electric property so that the effective separation has been realized.

Physicochemical Attributes in Mango Fruit (Mangifera indica) as Influenced by Storage Temperature and Hot Water Treatment

Background: The temperature being the most important environmental factor that influences the deterioration of perishable commodities. It is often critical that fresh produce rapidly reach the optimal pulp temperature for short term storage if it is to maintain its highest visual quality, flavour, texture and nutritional content (Kader, 2013). Aims: The effects of storage temperature and hot water at various temperature and duration on chemical and textural characteristics of the Keitt mango fruit were evaluated for the 2015/16 growing season in Botswana. Materials and Methods: The treatments were fruits dipped in distilled water at room temperature (25±2ºC- control), fruits dipped in hot water at 50 and 55ºC for a duration of 3, 5 and 10 minutes, and storage temperatures at 4, 7, 10, 13, or 25±2ºC, plus 95% RH. Results: The results showed that as the storage temperature and water temperature decreased, the proline content and electrolyte leakage increased significantly (P ≤ 0.0001). The interactions of storage temperature and hot water temperature, and duration in which mango fruit was treated with hot water, significantly (P ≤ 0.01) maintained vitamin C content, firmness and reduced fruit weight loss during storage and seven days after storage when the fruit was kept at room temperature. Conclusion: Chemical and physical attributes of Keitt mango fruits were significantly improved by the interactions between storage temperature, hot water temperature and duration.