Modelling of Discolouration of Dried Powder of Carrots

A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O₂and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted.     

Some environmental problems associated with the use of treated wastewater for irrigation in Jordan

Treated effluent was used for eggplant (aubergine) irrigation through a trickle system at As-Samra experimental site. The soil characteristics were determined prior to irrigation. Physical, chemical and biological characteristics of the effluent were determined during the growing season. Suitability of the effluent for irrigation was studied. The crop and soil were tested for pathogenic pollution. The accumulation of salts and heavy metals in the soil as well as concentration of the nutrients and heavy metal accumulation in the plant tissues were determined. Clogging of the irrigation system was evaluated and treated. Yield was determined.Results of the study showed that the effluent has a low heavy metal content. It showed moderate restriction for surface trickle irrigation. Regarding the microbiological quality of the treated wastewater, it was found that the faecal coliform ranged from 2.1 × 10³ to 1.8 × 10 Most Probable Number (MPN) per 100 ml at the irrigated site, while it is free from nematode eggs. The soil surface under the effluent irrigation water was found to contain faecal coliform, but the count drastically decreased with depth. Except for a very low coliform count on fruit skins, no colifonn count was found on the crop leaves, whether they were free or in contact with the soil. The effluent showed a rather high concentration of chlorophyll a due to the presence of algae. Results of soil analysis after eggplant harvest showed a slight increase in heavy metals and salt accumulation at the periphery of the wet zone. Nutrients and heavy metal concentration in eggplant tissue under treated effluent irrigation was within the normal range in agricultural crops. Although filtration of the effluent was not practised, there was minimum clogging of the irrigation system. This clogging was successfully controlled with acid and chlorine. Eggplant yield under treated effluent was twice the average eggplant production under fresh water irrigation using conventional fertiliser application in Jordan.     

Tree species-rich open oak woodlands within scattered urban landscapes promote biodiversity

It is becoming increasingly evident that cities are important places for biodiversity. Biodiverse urban forests are vital green areas within cities and have favorable impacts on the citizens, including their health. We focused on the effect of the urban forest environment on biodiversity in Prague, the capital of the Czech Republic. We used a multi-taxon approach with five taxa of different ecological demands: butterflies, bees and wasps, vascular plants, mosses, and lichens. We modeled their responses to the various urban forest attributes at four hierarchical levels – plot, permeability, forest, and landscape. Our results revealed that temporally continuous forests dominated by native oaks with open canopies, a high number of admixed and interspersed tree species and shrubs, together with scattered trees in the surrounding landscape, were optimal biodiverse forest environments. The most influential parameter that positively influenced bees and wasps, plants, and lichens at the plot level was canopy openness. We found that the permeability was suitable mainly on 20 m surroundings and increasing coverage of native oaks and tree species richness were the most important parameters. Continuity was the only found parameter that influenced mosses at the forest level. Scattered tree vegetation was the most important landscape parameter and positively drove the species richness of bees and wasps. Forest management methods can relatively easily solve the improvement of the scattered light gap structure within urban forests. Applying traditional forest management (pasture management, controlled burning and/or coppicing) is also an option but requires sensitive communication with the public. The canopy cover has been used as an indicator of urban forest health conditions, now indicating that artificial disturbances could be important issues for urban forest management and planning in the future. Therefore, active forest management is an essential method for biodiversity maintenance. We conclude that urban forests have a high potential for increasing native biodiversity. The response of the studied groups in urban forests was complementary. The resulting biodiverse stages of urban forests are akin to the established idea of the open temperate deciduous woodlands.     

Potential use of the scheduler plant stress monitor in soybean

Much of work relating plant temperature to plant water stress has been done in arid regions. In 1989–1990, investigations were carried out verifying the validity of the Scheduler Plant Stress Monitor made by the Standard Oil Engineering Materials Company of the United States, in irrigation timing, under Hungary's changeable weather conditions.Three different water treatments were used:

• 1.⊎ natural rainfall only (control),
• 2.⊎ lysimeter study, where the water supply is in accordance with the water demand of plants,
• 3.⊎ irrigation according to the instructions of the Scheduler.

The monitor compares plant and air temperature differences to calculate stress index and irrigation timing. The measured indices were corrected for wind speed.Taking the varied water levels into account, the highest grain yield occurred in canopies watered by using the Scheduler instructions. In 1989, the yield increase was more moderate (16.5%) than that of the yield surplus in dry 1990 (38.1%), comparing to the results of non-irrigated control.The water-use efficiency in plant stands grown by the Scheduler control fell between the results of non-irrigated control and lysimeter study, independent of weather conditions.Use of the Scheduler may be recommended mainly in arid growing seasons, where yield increase is high enough to compensate for the additional cost of irrigation water. In Hungary, where the weather is very changeable it cannot be stated with complete confidence that the Scheduler is always an effective tool in irrigation planning. To clarify this problem further work is needed.     

On appraising soil erosion menace and control measures in Southeastern Nigeria

Sheet erosion poses problems as serious as gully incisions in Southeastern Nigeria. A regional erosion control authority is needed to evaluate, monitor and enforce control measures. Additional vital prerequisites for the implementation of effective erosion control scheme in the region include; recognition that control measures are soil and site specific; ability to predict soil loss under any postulated condition; the availability of vital information and data required for designing effective engineering control measures; and dissemination of information on contemplated control measures among the population, particularly the farmers.     

多孔介质壁面条件下微尺度流动的数值模拟

利用多孔介质模拟微通道壁面粗糙元,建立了一种新的微尺度化流场的数值模拟方法.多孔介质模型厚度由微通道壁面相对粗糙度折算,多孔介质的阻力系数由该区域内的流态及阻力计算;配合采用k-ε和k-ω多种形式的湍流模型,对边长为600μm的方形断面微通道流场在雷诺数分别为100和300的情况下进行了数值模拟计算.通过模拟结果与Micro-PIV测量数据的对比分析发现,采用realizablek-ε湍流模型,搭配多孔介质微尺度化模型进行数值计算,能够有效地模拟微尺度流场的流动状况,而标准k-ε湍流模型和RNGk-ε湍流模型的微尺度模拟计算结果虽接近试验测量值,但仍有偏差;标准k-ω湍流模型和SSTk-ω湍流模型的微尺度模拟效果较差.     

Valuing urban trees: A hedonic investigation into tree canopy influence on property values across environmental and social contexts in Baltimore,Maryland

Urban tree canopy yields numerous environmental and social benefits. This study investigates whether the marginal contribution of tree canopy cover to home values depends on certain characteristics of a property and its location. We address this using a hedonic property analysis with data from Baltimore, Maryland. Both Ordinary Least Square and Spatial Lag models were conducted, all including interaction terms between tree canopy cover and various site factors. Our results indicated that, on average, the amount of tree canopy in the 100–400 zone around a single-family property is positively associated with home price. We also find that the marginal impact of canopy on property price increases for properties that are larger in lot size and closer to downtown Baltimore. Model results were mixed in terms of the interactive effects of crime and proximity to major roadway with tree canopy. We suggest that the benefits that tree canopy provides in the form of added privacy, reduced urban heat, noise and pollution may influence these price increases. These findings may signal concerns about the potential for urban greening to contribute to gentrification. In a competitive housing market, those with the capacity to afford to pay more for urban tree canopy and the benefits it provides such as a cooler downtown environment, privacy on larger lots, or reduced noise and pollution from a major roadway may price out those who are unable to pay this urban tree canopy premium. There is, therefore, the potential for unequal increases in home equity across neighborhoods following tree planting and urban greening in Baltimore.     

Flowers as attractions in urban parks: Evidence from social media data

Urban parks are among the most important urban public services. Quantifying their visitation intensity and understanding the driving forces behind their popularity is of great relevance to urban planning. We analyze the behavior of park visitors in Beijing based on phenological information extracted from social media data. Specifically, we built a dataset utilizing natural language processing techniques and co-word analysis methods to explore the connection between flowers and park visitation. Our findings revealed that: (1) According to the changing trend of visitor volumes and their peak times, urban parks can be divided into “single-peak” (visitor volumes show a single peak, with significant seasonal characteristics) and “multi-peak” (visitor volumes show multiple peaks with no obvious seasonal characteristics) parks; (2) There is an association between flowers and visitor volumes to urban parks, with a noticeable increase in the frequency of visits to parks especially in spring (i.e., during flowering); (3) Different types of flowers have varying appeal to attract visitors. Further, parks with one or few “dominant flowers” appeal to more visitors than parks without a clear dominating flower (or flowers). Our results provide implications for urban park design and management for improving their scenic qualities.     

Silvicultural treatments for sapling mesquite (Prosopis glandulosa var. glandulosa) to optimize timber production and minimize seedling encroachment

To maximize lumber production and minimize weed problems with Prosopis glandulosa, silvicultural treatment methods were evaluated nine years after initiation. A randomized complete block design was used with four replicates and six treatments. Plots were shredder-harvested leaving sixteen 2-m squares on 10-m spacing that included a final rotation crop tree. In three of the treatments the crop trees were pruned to a single stem. To prevent re-establishment of mesquite in the interstitial areas, plots were spot sprayed with herbicides, disked, or disked and seeded with rye grass in 1986. Herbicide treatments and disking continued yearly through 1989. In 1991, disk treatments were repeated. After both 2.5 and 9 yrs, significant treatment differences were found for growth of basal diameter, growth of basal area, and growth of dry weight. The greatest crop tree growth occurred in treatments that were pruned with interstitial competition suppressed. Mortality was greatest in the dense treatments, while re-establishment of mesquite was greatest in the more open treatments. The greatest basal diameter growth of 1.21 cm year⁻¹ in the disked and pruned treatments is comparable to other fine hardwoods in temperate and dry tropical forests.