Energy Crops and Methane: Process Optimization of Ca(OH)2 Assisted Thermal Pretreatment and Modeling of Methane Production.

Switchgrass earned its place globally as a significant energy crop by possessing essential properties such as being able to control erosion, low cost of production, biomass richness, and appeal for biofuel production. In this study, the impact of a Ca(OH)2-assisted thermal pretreatment process on the switchgrass variety Shawnee for methane fuel production was investigated. The Ca(OH)2-assisted thermal pretreatment process was optimized to enhance the methane production potential of switchgrass. Solid loading (3-7%), Ca(OH)2 concentration (0-2%), reaction temperature (50-100 °C), and reaction time (6-16 h) were selected as independent variables for the optimization. Methane production was obtained as 248.7 mL CH4 gVS-1 under the optimized pretreatment conditions. Specifically, a reaction temperature of 100 °C, a reaction time of 6 h, 0% Ca(OH)2, and 3% solid loading. Compared to raw switchgrass, methane production was enhanced by 14.5%. Additionally, the changes in surface properties and bond structure, along with the kinetic parameters from first order, cone, reaction curve, and modified Gompertz modeling revealed the importance of optimization.

Effects of ripening stages and storage durations on resistance parameters of beef type tomatoes: part 1: spring period / Efeitos de estágios de maturação e durações de armazenamento em parâmetros de resistência de tomates coração de boi: parte 1: período de primavera

Following the harvest, agricultural products are subjected to various negative impacts throughout the way to consumers. Mechanical damages such as color darkening, abrasion, cuts, or punctures over the fruit surface are irreversible damages and such damages ultimately end up in significant quality and economic losses. In modern production systems, only a certain portion of the products directly reach from producer to consumers. The majority of these products are subjected to mechanical damages through the crush, squeeze, vibration, and similar impacts during the harvest and postharvest processes. In this study, Tybeef tomato cultivar grown over the experimental greenhouses of Bati Akdeniz Agricultural Research Institute (BATEM) (control) and 14-193 and 14-206 coded candidate cultivars developed through breeding programs of BATEM were used as the plant material. Resistance parameters of tomato cultivars were determined at 4 different ripening stages (green, turning, pink, and red) and 4 different storage durations (4, 8, 12, and 16 days). Resistance parameters decreased with the progress of ripening and storage durations. All measurements and assessments revealed that 14-193 coded candidate cultivars were prominent for resistance parameters.

Após a colheita, os produtos agrícolas estão sujeitos a diversos impactos negativos ao longo do caminho até os consumidores. Danos mecânicos como escurecimento da cor, abrasão, cortes ou perfurações na superfície da fruta são irreversíveis e acabam resultando em perdas significativas de qualidade e econômicas. Nos sistemas de produção modernos, apenas uma determinada parte dos produtos chega diretamente do produtor ao consumidor. A maioria desses produtos está sujeita a danos mecânicos por meio de esmagamento, compressão, vibração e impactos semelhantes durante os processos de colheita e pós-colheita. Neste estudo, a cultivar de tomate Tybeef cultivada em estufas experimentais do Bati Akdeniz Agricultural Research Institute (BATEM) (controle) e as cultivares candidatas codificadas 14-193 e 14-206 desenvolvidas por meio de programas de melhoramento do BATEM foram utilizadas como material vegetal. Os parâmetros de resistência dos cultivares de tomate foram determinados em 4 diferentes estágios de maturação (verde, pintado, rosado e vermelho) e 4 diferentes durações de armazenamento (4, 8, 12 e 16 dias). Os parâmetros de resistência diminuíram com o progresso do amadurecimento e durações de armazenamento. Todas as medições e avaliações revelaram que 14-193 cultivares candidatas codificadas eram proeminentes para os parâmetros de resistência.

A comprehensive review of thin-layer drying models used in agricultural products.

Drying is one of the widely used methods of grain, fruit, and vegetable preservation. The important aim of drying is to reduce the moisture content and thereby increase the lifetime of products by limiting enzymatic and oxidative degradation. In addition, by reducing the amount of water, drying reduces the crop losses, improves the quality of dried products, and facilitates its transportation, handling, and storage requirements. Drying is a process comprising simultaneous heat and mass transfer within the material, and between the surface of the material and the surrounding media. Many models have been used to describe the drying process for different agricultural products. These models are used to estimate drying time of several products under different drying conditions, and how to increase the drying process efficiency and also to generalize drying curves, for the design and operation of dryers. Several investigators have proposed numerous mathematical models for thin-layer drying of many agricultural products. This study gives a comprehensive review of more than 100 different semitheoretical and empirical thin-layer drying models used in agricultural products and evaluates the statistical criteria for the determination of appropriate model.

Infrared drying of strawberry.

The effects of different drying conditions, such as infrared power, drying air temperature and velocity, on quality of strawberry were evaluated. Drying time decreased with increased infrared power, air temperature and velocity. An increase in power from 100W to 300W, temperature from 60 to 80°C and velocity from 1.0m.s-1 to 2.0m.s-1 decreased fruit color quality index. For total phenol and anthocyanin content, 300W, 60°C, and 1.0m.s-1 were superior to the other experimental conditions. The drying processes increased N, P and K and decreased Ca, Mg, Fe, Mn, Zn and Cu contents. The optimal conditions to preserve nutrients in infrared drying of strawberry were 200W, 100°C and 1.5m.s-1.

Using eddy covariance sensors to quantify carbon metabolism of peatlands: a case study in Turkey.

Net ecosystem exchange (NEE) of carbon dioxide (CO(2)) was measured in a cool temperate peatland in northwestern Turkey on a continuous basis using eddy covariance (EC) sensors and multiple (non-)linear regression-M(N)LR-models. Our results showed that hourly NEE varied between -1.26 and 1.06 mg CO(2) m(-2) s(-1), with a mean value of 0.11 mg CO(2) m(-2) s(-1). Nighttime ecosystem respiration (R(E)) was on average measured as 0.23 ± 0.09 mg CO(2) m(-2) s(-1). Two best-fit M(N)LR models estimated daytime R(E) as 0.64 ± 0.31 and 0.24 ± 0.05 mg CO(2) m(-2) s(-1). Total R(E) as the sum of nighttime and daytime R(E) ranged from 0.47 to 0.87 mg CO(2) m(-2) s(-1), thus yielding estimates of gross primary productivity (GPP) at -0.35 ± 0.18 and -0.74 ± 0.43 mg CO(2) m(-2) s(-1). Use of EC sensors and M(N)LR models is one of the most direct ways to quantify turbulent CO(2) exchanges among the soil, vegetation and atmosphere within the atmospheric boundary layer, as well as source and sink behaviors of ecosystems.

Assessing monthly average solar radiation models: a comparative case study in Turkey.

Solar radiation data are required by solar engineers, architects, agriculturists, and hydrologists for many applications such as solar heating, cooking, drying, and interior illumination of buildings. In order to achieve this, numerous empirical models have been developed all over the world to predict solar radiation. The main objective of this study is to examine and compare 147 solar radiation models available in the literature for the prediction of monthly solar radiation at Ankara (Turkey) based on selected statistical measures such as percentage error, mean percentage error, root mean square error, mean bias error, and correlation coefficient. Our results showed that Ball et al. (Agron J 96:391-397, 2004) model and Chen et al. (Energy Convers Manag 47:2859-2866, 2006) model performed best in the estimation of solar radiation on a horizontal surface for Ankara.

Long-term spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey.

This study quantified spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey between 1961 and 2007. CH4(enteric) (from enteric fermentation), CH4(manure) (from manure management), and N2O(AWM) (from animal waste management) emissions in Turkey were estimated at 1,164, 216, and 55 Gg in 1961 and decreased to 844, 187, and 39 Gg in 2007, contributing a share of roughly 2% to the global livestock-related CH4 emissions and %1.5 to the global N2O(AWM) emissions, respectively. Total CO2-eq emissions were estimated at 50.7 Tg in 1961 and declined from a maximum value of 60.7 Tg in 1982 to a minimum value of 34.5 Tg in 2003, with a mean emission rate of 48 Tg year(-1) due to a significant reduction in the number of ruminant livestock. The highest mean share of emissions belonged to West Black Sea (14% and 16%) for CH4(enteric) and CH4(manure) and to North East Anatolia (12% and %13) for N2O(AWM) and total CO2-eq emissions, respectively. The highest emission density was 1.7 Mg km(-2) year(-1) for CH4(enteric), 0.3 Mg km(-2) year(-1) for CH4(manure), and 0.07 Mg km(-2) year(-1) for the total CO2-eq emissions in the West and North East Anatolia regions and 0.09 Mg km(-2) year(-1) for N2O(AWM) in the East Marmara region. Temporal and spatial variations in CH4(enteric), CH4(manure), and N2O(AWM) emissions in Turkey were estimated using regression models and ordinary kriging at a 500-m resolution, respectively.

Techno-Economic Analysis of Solar Water Heating Systems inTurkey.

In this study, solar water heater was investigated using meteorological and geographical data of 129 sites over Turkey. Three different collector types were compared in terms of absorber material (copper, galvanized sheet and selective absorber). Energy requirement for water heating, collector performances, and economical indicators were calculated with formulations using observed data. Results showed that selective absorbers were most appropriate in terms of coverage rate of energy requirement for water-heating all over Turkey. The prices of selective, copper and galvanized absorber type's heating systems in Turkey were 740.49, 615.69 and 490.89 USD, respectively. While payback periods (PBPs) of the galvanized absorber were lower, net present values (NPVs) of the selective absorber were higher than the rest. Copper absorber type collectors did not appear to be appropriate based on economical indicators.

Modeling Spatio-Temporal Dynamics of Optimum Tilt Angles for Solar Collectors in Turkey.

Quantifying spatial and temporal variations in optimal tilt angle of a solar collector relative to a horizontal position assists in maximizing its performance for energy collection depending on changes in time and space. In this study, optimal tilt angles were quantified for solar collectors based on the monthly global and diffuse solar radiation on a horizontal surface across Turkey. The dataset of monthly average daily global solar radiation was obtained from 158 places, and monthly diffuse radiation data were estimated using an empirical model in the related literature. Our results showed that high tilt angles during the autumn (September to November) and winter (December to February) and low tilt angles during the summer (March to August) enabled the solar collector surface to absorb the maximum amount of solar radiation. Monthly optimum tilt angles were estimated devising a sinusoidal function of latitude and day of the year, and their validation resulted in a high R² value of 98.8%, with root mean square error (RMSE) of 2.06o.

Modeling Potential Distribution and Carbon Dynamics of Natural Terrestrial Ecosystems: A Case Study of Turkey.

We derived a simple model that relates the classification of biogeoclimatezones, (co)existence and fractional coverage of plant functional types (PFTs), and patternsof ecosystem carbon (C) stocks to long-term average values of biogeoclimatic indices in atime- and space-varying fashion from climate-vegetation equilibrium models. ProposedDynamic Ecosystem Classification and Productivity (DECP) model is based on the spatialinterpolation of annual biogeoclimatic variables through multiple linear regression (MLR)models and inverse distance weighting (IDW) and was applied to the entire Turkey of780,595 km² on a 500 m x 500 m grid resolution. Estimated total net primary production(TNPP) values of mutually exclusive PFTs ranged from 108 26 to 891 207 Tg C yr-1under the optimal conditions and from 16 7 to 58 23 Tg C yr-1 under the growth-limiting conditions for all the natural ecosystems in Turkey. Total NPP values ofcoexisting PFTs ranged from 178 36 to 1231 253 Tg C yr-1 under the optimalconditions and from 23 8 to 92 31 Tg C yr-1 under the growth-limiting conditions. Thenational steady state soil organic carbon (SOC) storage in the surface one meter of soil wasestimated to range from 7.5 1.8 to 36.7 7.8 Pg C yr-1 under the optimal conditions andfrom 1.3 0.7 to 5.8 2.6 Pg C yr-1 under the limiting conditions, with the national range of 1.3 to 36.7 Pg C elucidating 0.1% and 2.8% of the global SOC value (1272.4 Pg C), respectively. Our comparisons with literature compilations indicate that estimated patterns of biogeoclimate zones, PFTs, TNPP and SOC storage by the DECP model agree reasonably well with measurements from field and remotely sensed data.

Statistical Modeling of Spatio-Temporal Variability in Monthly Average Daily Solar Radiation over Turkey.

Though one of the most significant driving forces behind ecological processessuch as biogeochemical cycles and energy flows, solar radiation data are limited or non-existent by conventional ground-based measurements, and thus, often estimated from othermeteorological data through (geo)statistical models. In this study, spatial and temporalpatterns of monthly average daily solar radiation on a horizontal surface at the ground levelwere quantified using 130 climate stations for the entire Turkey and its conventionally-accepted seven geographical regions through multiple linear regression (MLR) models as afunction of latitude, longitude, altitude, aspect, distance to sea; minimum, maximum andmean air temperature and relative humidity, soil temperature, cloudiness, precipitation, panevapotranspiration, day length, maximum possible sunshine duration, monthly average dailyextraterrestrial solar radiation, and time (month), and universal kriging method. Theresulting 20 regional best-fit MLR models (three MLR models for each region) based onparameterization datasets had R²adj values of 91.5% for the Central Anatolia region to 98.0%for the Southeast Anatolia region. Validation of the best-fit MLR models for each region led to R2 values of 87.7% for the Mediterranean region to 98.5% for the Southeast Anatoliaregion. The best-fit anisotropic semi-variogram models for universal kriging as a result ofone-leave-out cross-validation gave rise to R² values of 10.9% in July to 52.4% inNovember. Surface maps of monthly average daily solar radiation were generated overTurkey, with a grid resolution of 500 m x 500 m.