Mm Of Water Research Articles

Yield, irrigation response, and water productivity of deficit to fully irrigated spring canola

Canola (Brassica napus) is an oil-seed crop that is adapted to the northern High Plains of the USA and is considered a viable rotational and biofuel crop. However, decreased ground water allocations have necessitated determining the impact of limited irrigation on canola productivity. The objectives of this research were to determine the effects of a range of irrigation from none to fully irrigated on yield, oil content, soil water changes and water productivity of spring canola. The study was conducted for four growing seasons at three locations in western Nebraska. Two sites had sandy soils whereas the other was a silt loam. Glyphosate tolerant canola was planted late March to early April. Cumulative irrigation treatments were 0, 100, 200, and 300mm of water with the highest rate adjusted to be non-ET limiting. Canola extracted soil water from depths greater than 1.2m in both fine textured and sandy soils making it a good alternative for deficit irrigation. Canola responded well to irrigation during dry years but showed little response in above average precipitation years. A water use efficiency of 7.6kgmm−1 with a threshold of 123mm was observed. Canola seed yield ranged from 440 to 3280kgha−1 with 165 and 582mm of cumulative ET. During drier years, canola exhibited peak values in water use at 8–9 weeks after planting. Deficit irrigation reduced ET and yield and hastened maturity during drier years. Oil content was increased by irrigation during drier years with no effect shown when precipitation was above average. Oil content ranged from 30 to 50% depending on year and irrigation level. The water response provided benefits of not only higher yield, but also higher oil content which makes deficit irrigated canola an attractive alternative production and biofuel crop for this region.

Dosimetric characteristics of brass mesh as bolus under megavoltage photon irradiation.

This article presents a set of dosimetric measurements describing the properties of brass mesh (Whiting and Davis, Attleboro Falls, MA) under megavoltage photon irradiation conditions, with particular relevance to its use in breast radiotherapy. The effectiveness of brass mesh as a bolus material was investigated using 6-, 15- and 6-MV flattening filter-free photon beams. The effect on dose build-up at the entrance surface, build-down at the beam-exit surface, dose with surface entrance obliquity, beam profiles, penumbra and percentage depth doses were investigated. One layer of the brass mesh produces a build-up effect equivalent to 1.1 mm of water at 6 MV and 1.9 mm at 15 MV. The brass generates a backscattered component of dose, if the photon beam exits through it. Percentage depth-dose curves are largely unaffected by the mesh and are shown to be equivalent to plain-field data. Beam penumbra and profiles are unchanged by the brass except within the first millimetre (mm) of phantom, where a periodic pattern of dose enhancement is seen. The data presented demonstrate that one layer of brass mesh provides a similar dose build-up effect equivalent to only a few millimetres of water. However, backscatter from the high atomic number (Z) mesh, at the beam exit, contributes appreciably to the overall dose surface enhancement. This dosimetric consequence cannot be neglected and indeed should be considered and accounted for, when determining the bolus effect of the brass mesh in the case of tangential breast irradiation. Advance in knowledge: This article provides dosimetric data necessary for the introduction of brass mesh bolus into the clinical setting for external-beam breast radiotherapy.

Probability analysis of rainfall and crop water requirement using CROPWAT model for crop planning in a canal command of upper Bhima Basin of Maharashtra

Rainfall is the most important climatic parameters influencing agriculture in Pune district of Maharashtra. Rainfall of this region is highly variable with respect to space and time and about 80–90% of precipitation falls in monsoon period from June to October resulting in drought and flood situation in the upper Bhima basin of Maharashtra. Therefore, for efficient water resources management, optimal crop planning and also for better understanding of rainfall behavior (i.e., distribution and minimum expected amount during crop growing period) probability analysis of rainfall was conducted. Probability analysis (at 50% and 80%) of monthly rainfall data of 13 raingauge stations of the left bank canal of upper Bhima basin viz., Urali, Loni Karbol, Kasurdi, Tajuproject, Yewat, Dahitane, Bhigwan, Madanwadi, Pondewadi, Kedgaon, Patas, Pimplegaon and Daund for the period from 1975 to 2002 was conducted. Reference evapotranspiration (ETo) has been calculated using climatic parameters like sun shine hour, wind speed, maximum & minimum temperature and rainfall humidity for the period from years 1993–2005 by CROPWAT model. It was found that ETo is maximum (7.72 mm/day) during April and low in December (3.10 mm/day). Effective rainfall of existing rain gauge stations falling in different sub-basins, BM48, BM49, BM50, BM51 and BM68 have been estimated using the CROPWAT model. Finally net irrigation requirement of crops Kharif Cotton, Summer Cotton, Sugarcane and Rabi Sorghum have been find out for all the sub-basin. From this study it has been concluded that, the crop planning in the area, represented by Pimplegoan and Urali stations should be done keeping in mind maximum deficit of 187 mm and 113 mm of water respectively during July. Similarly in other stations maximum deficit of water was observed during September which indicate that while selection of crops for the areas represented by these stations the crops requiring less water during September should be selected.

An Overview of the Control System for Dose Delivery at the UCSF Dedicated Ocular Proton Beam

Since 1978, the University of California San Francisco (UCSF) Ocular Tumor Program has been using particle therapy for treating ocular patients with malignant as well as benign eye disease. Helium ion beams were used initially and were produced by two synchrotron-based systems: first by the 184-inch synchro-cyclotron and later by the Bevalac, at the Lawrence Berkeley National Laboratory (LBNL). Since 1994, protons, produced by a cyclotron-based system at the Crocker Nuclear Laboratory (CNL) Eye Treatment Facility (ETF), have been used for this purpose. The CNL cyclotron produces a 67.5 MeV beam, allowing for a uniquely homogeneous beam for eye treatment, without degradation of the beam or manipulation of the beam line. This paper describes, in detail, the control system for beam delivery, as implemented for measuring and delivering the radiation to ocular tumors at CNL. The control system allows for optimal delivery and rapid termination of the irradiation after the desired dose is achieved. In addition, several safeguard systems are discussed, as these are essential for such a system in the event of failure of software, electronics, or other hardware. The QA analysis shows that the total range of the proton beam is 30.7 ± 1.0 mm in water at iso-center. The beam distal penumbra (80% - 20%) is 1.1 mm for a range-modulated beam at a collimator to iso-center distance of 50 mm. Daily QA checks confirm that the range and modulation is within 0.1 mm. The beam flatness and symmetry in a 25 mm diameter beam are ±1% - 2%. Variation in the daily dosimetry system, as compared to standard dosimetry, is within ±3.5%, with a mean variation of 0.72(±1.9)% and 0.85(±2.3)% for segmented transmission ionization chambers IC1 (upstream) and IC2 (downstream), respectively. From May 1994 to the end of 2015, UCSF has treated 1838 proton ocular patients at the Davis ETF. During this period, no treatments were missed due to any cyclotron or control system failures. The overall performance, maintenance, and quality assurance of the cyclotron and the ocular control system have been excellent.

Acoustic band structures in two-dimensional phononic crystals consisting of periodic square arrays of stainless-steel cylinders in water

The present study aims to investigate experimentally and theoretically the acoustic band structures in two-dimensional phononic crystals (PCs) consisting of periodic square arrays of stainlesssteel solid cylinders with diameters of 1.0 mm in water. Two types of PCs with different lattice constants (a), 1.5 and 3.0 mm, were assembled to investigate the influence of structural parameters on their band gaps. The dispersion relations were calculated along the ΓX direction of the first Brillouin zone by using the finite element method. The experimental and the theoretical transmission coefficients were obtained for 2, 4, 6, 8, and 10 layers of cylinders along the ΓX direction. The first band gap of the PC with a = 1.5 mm was found around a frequency of 0.5 MHz while that of the PC with a = 3.0 mm was found around 0.25 MHz. Relatively wide band gaps were observed in the PC with a = 1.5 mm compared to that with a = 3.0 mm. The combination of the two different PCs in tandem with different structural parameters was demonstrated to lead to a superposition of their individual band gaps.

СОЛНЕЧНАЯ РАДИАЦИЯ В ОЦЕНКАХ МАКСИМАЛЬНОЙ УРОЖАЙНОСТИ ЯРОВЫХ КУЛЬТУР

Рассмотрен физиолого-метеорологический энергобалансовый подход к оценке прихода к посевам солнечной радиации, включая фотосинтетически активную радиацию (ФАР), и ее использования на фотосинтез, влагопотребление и транспирацию, теплообмен со средой, регуляторно-информационные фотобиологические процессы, фотоморфогенез. Этот подход позволяет определить максимально возможную продуктивность (МВП) и урожайность (МВУ) яровых зерновых культур в оптимальных по другим параметрам условиях роста. Отмечена роль критических радиационных периодов (КРП) в онтогенезе растений и возможность их учета в новых методах агрометеорологических прогнозов урожайности. Проведен расчет прихода ФАР за период от всходов до конца цветения к посевам пшеницы и ячменя для Московской, Курской, Тамбовской, Воронежской, Самарской, Саратовской областей. Показано, что величина МВП может составлять 130–140 ц/га, а МВУ – 38–42 ц/га. В оптимальных условиях более 90% ФАР расходуется на транспирацию (Т); для получения МВП необходимо использовать на Т около 180 мм влаги в 1 м слоя почвы. Так как у пшеницы и ячменя Т осуществляется лишь на свету и пропорциональна газообмену, при снижении запасов продуктивной влаги (ЗПВ) в той же мере снижается Т и газообмен. Рассчитана максимально возможная действительная урожайность: 38–40 ц/га в Московской и Курской, 31–33 ц/га в Тамбовской и Воронежской и около 28 ц/га в Самарской и Саратовской областях. Подчеркивается, что снижение прихода ФАР и ЗПВ снижает газообмен и прирост массы, особенно в критические радиационные периоды онтогенеза, и поэтому учет ФАР важен как для оценки состояния посевов, так и прогноза возможной урожайности.

A new approach to estimate canopy evaporation and canopy interception capacity from evapotranspiration and sap flow measurements during and following wetting

Canopy interception and its evaporation into the atmosphere during irrigation or a rainfall event are important in irrigation scheduling, but are challenging to estimate using conventional methods. This study introduces a new approach to estimate the canopy interception from measurements of actual total evapotranspiration (ET) using eddy covariance and estimation of the transpiration from measurements of sap flow. The measurements were conducted over a small-scale sprinkler-irrigated cotton field before, during and after sprinkler irrigation. Evaporation and sap flow dynamics during irrigation show that the total ET during irrigation increased significantly because of the evaporation of free intercepted water while transpiration was suppressed almost completely. The difference between actual ET and transpiration (sap flow) during and immediately following irrigation (post irrigation) represents the total canopy evaporation while the canopy interception capacity was calculated as the difference between actual ET and transpiration (sap flow) during drying (post irrigation) following cessation of the irrigation. The canopy evaporation of cotton canopy was calculated as 0.8 mm, and the interception capacity was estimated to be 0.31mm of water. The measurement uncertainty in both the non-dimensional ET and non-dimensional sap flow was shown to be very low.

Managing Phosphorus Leaching in Mid‐Atlantic Soils: Importance of Legacy Sources

Core Ideas Higher P leaching from P‐saturated mid‐Atlantic soils. Preferential flow caused more P leaching in fine‐textured soils. Matrix flow reduced P leaching from coarse‐textured soils. Use both P saturation ratio and flow pathways to predict the risk of P leaching. Application of phosphorus (P) inputs to soils saturated with legacy P can significantly increase the risk of P leaching and deteriorate water quality. Our objectives were to quantify the effect of soil type and extent of P saturation on P leaching and determine the suitability of a rapid, inexpensive soil P saturation test for use in P leaching risk assessment protocols. We collected 18 undisturbed lysimeters (30‐cm diameter, 50 cm deep), using a tractor‐mounted corer, from three typical mid‐Atlantic soils in Delaware, where P leaching is a concern. The soils were selected on the basis of Mehlich‐3 P saturation ratio (M3‐PSR) of optimum (<0.10) to environmental (>0.15) thresholds. Lysimeters were irrigated with the equivalent of 50 mm of water each week for a total of 16 wk. Concentrations of dissolved reactive P (DRP) and total P in leachate were not significantly different between optimum and environmental M3‐PSR lysimeters before fertilizer application (Weeks 1–8). However, concentrations of DRP and total P significantly increased after fertilizer application at 85 kg P ha−1 (Weeks 9–16) in the environmental M3‐PSR lysimeters. Among three soils in both M3‐PSR categories, concentrations and loads of P leached were higher from the Matapeake silt loam and Pocomoke sandy loam due to preferential leaching that limited contact of flowing water and P with the soil P‐fixing constituents (Fe, Al, and Ca), while P leaching was lower from Woodstown sandy loam due to matrix flow that resulted in greater interaction of water and P with the soil constituents. These results provide clear evidence of a greater risk of P leaching from P‐saturated soils with preferential flow pathways and show that the M3‐PSR along with information about preferential flow pathways should be used to predict the risk of P leaching.

Radiolytic corrosion of uranium dioxide induced by He2+ localized irradiation of water: Role of the produced H2O2 distance

The short-range (few μm in water) of the α-emitting from the spent fuel involves that the radiolytic corrosion of this kind of sample occurs at the solid/solution interface. In order to establish the role of localization of H2O2 species produced by the He2+ particle beam in water from the surface, we perform UO2 radiolytic corrosion experiment with different distance between H2O2 production area and UO2 surface. Then, in this work, the radiolytic corrosion of UO2 particles by oxidative species produced by 4He2+ radiolysis of water was investigated in open to air atmosphere. The dose rate, the localization of H2O2 produced by water radiolysis and the grain boundaries present on the surface of the particles were investigated. UO2 corrosion was investigated by in situ (during irradiation) characterization of the solid surface, analysis of H2O2 produced by water radiolysis and quantification of the uranium species released into the solution during irradiation. Characterization of the UO2 particles, surface and volume, was realized by Raman spectroscopy. UV–vis spectrophotometry was used to monitor H2O2 produced by water radiolysis and in parallel the soluble uranium species released into the solution were quantified by inductively coupled plasma mass spectrometry. During the He2+ irradiation of ultra-pure water in contact with the UO2 particles, metastudtite phase was formed on the solid surface indicating an oxidation process of the particles by the oxidative species produced by water radiolysis. This oxidation occurred essentially on the grain boundaries and was accompanied by migration of soluble uranium species (U(VI)) into the irradiated solution. Closer to the surface the localization of H2O2 formation, higher the UO2 oxidation process occurs, whereas the dose rate had no effect on it. Simultaneously, closer to the surface the localization of H2O2 formation lower the H2O2 concentration measured in solution. Moreover, the metastudtite was the only secondary phase formed whatever the irradiation conditions. One hypothesis proposed in this work is the H2O2 may undergo a dismutation reaction leading to the formation of OH at the UO2 surface.

Dynamic criteria of plankton jumping out of water.

In nature, jumping out of water is a behaviour commonly observed in aquatic species to either escape from predators or hunt prey. However, not all aquatic species are capable of jumping out, especially small organisms whose length scales are comparable to the capillary length (approx. 2.7 mm for water). Some aquatic animals smaller than the capillary length are able to jump out while others are not, as observed in some marine copepods. To understand the dynamics of jumping out of the water-air interface, we perform physical experiments by shooting a spherical particle towards the liquid-air interface from below. Experimental results show that the particle either penetrates or bounces back from the interface, depending on the particle and fluid properties, and the impact velocity. The transition from bouncing to penetration regimes, which is theoretically predicted based on a particle force balance, is in good agreement with both physical experiments and plankton behavioural data.

수중에서 정방형 격자를 갖는 2차원 포노닉 크리스탈의 음향 밴드 구조

포노닉 크리스탈이란 기저물질 내에 주기적으로 배열된 산란체로 구성된 복합물질로서 포노닉 크리스탈에 입사된 음파가 특정 주파수 대역에서 차단되는 현상인 밴드 갭이라는 중요한 특성을 갖는다. 본 연구에서는 수중에서 산란체로서 1 mm의 직경을 갖는 원기둥 형태의 스테인리스 스틸 막대가 1.5 mm의 격자상수를 가지며 정방형으로 배열된 2차원 포노닉 크리스탈의 음향 밴드 구조를 이론 및 실험적으로 고찰하였다. 2차원 포노닉 크리스탈의 밴드 구조를 예측하기 위해 유한요소법을 이용하여 첫째 브릴루앙 영역의 <TEX>${\Gamma}X$</TEX> 방향에 대해 주파수와 파동벡터에 대한 분산관계를 계산하였다. 초음파가 입사되는 방향과 수직한 스테인리스 스틸 막대 층의 개수를 1, 3, 5, 7, 9개로 변화시켜가며 투과계수 및 반사계수를 측정하였다. 계산된 분산관계로부터 2 MHz 이하의 주파수 대역에서 5개의 밴드 갭이 존재하는 것으로 예측되었으며, 첫째 밴드 갭은 0.5 MHz를 중심으로 나타났다. 투과계수 및 반사계수로부터 실험적으로 확인된 밴드 갭은 분산관계로부터 예측된 밴드 갭과 잘 일치하는 것으로 나타났다. Phononic crystals are composite materials consisting of a periodic arrangement of scattering inclusions in a host material. One of the most important properties of phononic crystals is the existence of band gaps, i.e., ranges of frequencies at which acoustic waves cannot propagate through the structure. The present study aims to investigate theoretically and experimentally the acoustic band structures in two-dimensional (2D) phononic crystals consisting of periodic square arrays of stainless steel solid cylinders with a diameter of 1 mm and a lattice constant of 1.5 mm in water. The theoretical dispersion relation that depicts the relationship between the frequency and the wave vector was calculated along the <TEX>${\Gamma}X$</TEX> direction of the first Brillouin zone using the finite element method to predict the band structures in the 2D phononic crystals. The transmission and the reflection coefficients were measured in the 2D phononic crystals with 1, 3, 5, 7, and 9 layers of stainless steel cylinders stacked in the perpendicular direction to propagation at normal incidence. The theoretical dispersion relation exhibited five band gaps at frequencies below 2 MHz, the first gap appearing around a frequency of 0.5 MHz. The location and the width of the band gaps experimentally observed in the transmission and the reflection coefficients appeared to coincide well with those determined from the theoretical dispersion relation.

CHARACTERIZATION MORPHOAGRONOMIC OF GUAVA FRUITS UNDER DIFFERENT WATER DEPTHS AND NITROGEN FERTLIZATION LEVELS

ABSTRACT: The objective of this study was to evaluate the effects of different water depths and nitrogen fertilization levels applied by fertigation on the physical attributes of guava fruits cv. Paluma. The study was carried out taking into account factors water depths (1144, 1465, 1785 and 2106 mm) and nitrogen fertilization levels (50, 100, 150 and 200 kg ha-1). The water depths 1730 and 1750 mm increased production and the average weight of guava fruit in, respectively, 25.1 and 31.6%. The applications 178 and 152 kg N ha-1 increased at 67.1% in the production of fruits and 16.3% the average fruit weight. The combined application of 150 kg N ha-1 and 1789 mm of water amounted to 63.3% of the total weight of fruit. The equatorial diameter of the fruit was influenced by individual water depths applied evidencing an increase of up to 26.8%. Already combinations 200 kg N ha-1 and 1746 mm of water increased the longitudinal diameter of the fruits by 18.77%. The application of water depth to 1144 mm, associated with 143 kg N ha-1 gave index of the most satisfactory way to guava fruit.

Cotton Water Use Efficiency under Two Different Deficit Irrigation Scheduling Methods

Declines in Ogallala aquifer levels used for irrigation has prompted research to identify methods for optimizing water use efficiency (WUE) of cotton (Gossypium hirsutum L). In this experiment, conducted at Lubbock, TX, USA in 2014, our objective was to test two canopy temperature based stress indices, each at two different irrigation trigger set points: the Stress Time (ST) method with irrigation triggers set at 5.5 (ST_5.5) and 8.5 h (ST_8.5) and the Crop Water Stress Index (CWSI) method with irrigation triggers set at 0.3 (CWSI_0.3) and 0.6 (CWSI_0.6). When these irrigation triggers were exceeded on a given day, the crop was deficit irrigated with 5 mm of water via subsurface drip tape. Also included in the experimental design were a well-watered (WW) control irrigated at 110% of potential evapotranspiration and a dry land (DL) treatment that relied on rainfall only. Seasonal crop water use ranged from 353 to 625 mm across these six treatments. As expected, cotton lint yield increased with increasing crop water use but lint yield WUE displayed asignificant (p ≤ 0.05) peak near 3.6 to 3.7 kg ha−1 mm−1 for the ST_5.5 and CWSI_0.3 treatments, respectively. Our results suggest that WUE may be optimized in cotton with less water than that needed for maximum lint yield.

Yield, water use efficiency and economic analysis of energy sorghum in South Texas

Yields, water use efficiency and economic returns (net farm revenues) of biomass sorghum [Sorghum bicolor (L.) Moench] were investigated over two years (2012 and 2014) under limited water resource conditions. Energy sorghum was grown under four water supply regimes: rain-fed (or dry-land, level 1), 50% (level 2), 75% (level 3) and 100% (level 4) of crop evapotranspiration rates (% ETc). Biomass yields ranged from 5.8 to 16.6 Mg ha−1 (dry weight) after 126 days of growth. Average water use efficiencies ranged from 3.95 kg m−3 to 23.4 kg m−3. Net return was approximately 410 $ ha−1 with water depths above 400 ha-mm. These results suggest that it is possible to obtain more than 60 Mg ha−1 of sorghum biomass (wet basis) with at least 425 mm of water. While biomass yield under irrigation was greater than rain-fed conditions, there were no significant differences among irrigation treatments. Biomass chemical composition did not differ significantly among water treatments suggesting that biofuel quality would not be affected by water deficits.

Nitrogen Runoff Losses during Warm-Season Turfgrass Sod Establishment.

Concern exists over the potential loss of nitrogen (N) and phosphorus (P) in runoff from newly established and fertilized lawns. Nutrient losses can be higher from turf when shoot density and surface cover are low and root systems are not fully developed. This study was conducted to evaluate fertilizer source and timing effects on nutrient losses from newly sodded lawns of St. Augustinegrass [ (Walt.) Kuntze]. For each study, 12 33.6-m plots were established on an undisturbed Alfisol having a 3.7% slope. Each plot was equipped with a runoff collection system, instrumentation for runoff flow rate measurement, and automated samplers. A 28-d establishment study was initiated on 8 Aug. 2012 and repeated on 9 Sept. 2012. Treatments included unfertilized plots, fertilized plots receiving 4.88 g N m as urea 6 d after planting, fertilized plots receiving 4.88 g N m as sulfur-coated urea 6 d after planting, and fertilized plots receiving 4.88 g N m as urea 19 d after planting. Runoff events were created by irrigating with 17 mm of water over 27 min. Runoff water samples were collected after every 37.8 L and analyzed for NO-N, NH-N, dissolved organic N (DON), and PO-P. Increases of approximately 2 to 4 mg L NO-N and 8 to 12 mg L PO-P occurred in runoff 1 d after fertilization, which returned to background levels within 7 d. Total fertilizer N lost to runoff was 0.6 to 4.2% of that applied. Delaying fertilizer application until 19 d after planting provided no reduction in nutrient loss compared with a similar application 6 d after planting. Approximately 33% of the N lost in runoff was as DON. This large amount of DON suggests significant N loss from decomposing organic matter may occur during sod establishment.

Investigation of Water Dynamics and the Effect of Evapotranspiration on Grain Yield of Rainfed Wheat and Barley under a Mediterranean Environment: A Modelling Approach.

Agro-hydrological models have increasingly become useful and powerful tools in optimizing water and fertilizer application, and in studying the environmental consequences. Accurate prediction of water dynamics in such models is essential for models to produce reasonable results. In this study, detailed simulations were performed for water dynamics of rainfed winter wheat and barley grown under a Mediterranean climate over a 10-year period. The model employed (Yang et al., 2009. J. Hydrol., 370, 177-190) uses easily available agronomic data, and takes into consideration of all key soil and plant processes in controlling water dynamics in the soil-crop system, including the dynamics of root growth. The water requirement for crop growth was calculated according to the FAO56, and the soil hydraulic properties were estimated using peto-transfer functions (PTFs) based on soil physical properties and soil organic matter content. Results show that the simulated values of soil water content at the depths of 15, 45 and 75 cm agreed with the measurements well with the root of the mean squared errors of 0.027 cm3 cm-3 and the model agreement index of 0.875. The simulated seasonal evapotranspiration (ET) ranged from 208 to 388 mm, and grain yield was found to correlate with the simulated seasonal ET in a linear manner within the studied ET range. The simulated rates of grain yield increase were 17.3 and 23.7 kg ha-l for every mm of water evapotranspired for wheat and barley, respectively. The good agreement of soil water content between measurement and simulation and the simulated relationships between grain yield and seasonal ET supported by the data in the literature indicates that the model performed well in modelling water dynamics for the studied soil-crop system, and therefore has the potential to be applied reliably and widely in precision agriculture. Finally, a two-staged approach using inverse modelling techniques to further improve model performance was discussed.

Experimental depth dose curves of a 67.5 MeV proton beam for benchmarking and validation of Monte Carlo simulation.

To measure depth dose curves for a 67.5 ± 0.1 MeV proton beam for benchmarking and validation of Monte Carlo simulation. Depth dose curves were measured in 2 beam lines. Protons in the raw beam line traversed a Ta scattering foil, 0.1016 or 0.381 mm thick, a secondary emission monitor comprised of thin Al foils, and a thin Kapton exit window. The beam energy and peak width and the composition and density of material traversed by the beam were known with sufficient accuracy to permit benchmark quality measurements. Diodes for charged particle dosimetry from two different manufacturers were used to scan the depth dose curves with 0.003 mm depth reproducibility in a water tank placed 300 mm from the exit window. Depth in water was determined with an uncertainty of 0.15 mm, including the uncertainty in the water equivalent depth of the sensitive volume of the detector. Parallel-plate chambers were used to verify the accuracy of the shape of the Bragg peak and the peak-to-plateau ratio measured with the diodes. The uncertainty in the measured peak-to-plateau ratio was 4%. Depth dose curves were also measured with a diode for a Bragg curve and treatment beam spread out Bragg peak (SOBP) on the beam line used for eye treatment. The measurements were compared to Monte Carlo simulation done with geant4 using topas. The 80% dose at the distal side of the Bragg peak for the thinner foil was at 37.47 ± 0.11 mm (average of measurement with diodes from two different manufacturers), compared to the simulated value of 37.20 mm. The 80% dose for the thicker foil was at 35.08 ± 0.15 mm, compared to the simulated value of 34.90 mm. The measured peak-to-plateau ratio was within one standard deviation experimental uncertainty of the simulated result for the thinnest foil and two standard deviations for the thickest foil. It was necessary to include the collimation in the simulation, which had a more pronounced effect on the peak-to-plateau ratio for the thicker foil. The treatment beam, being unfocussed, had a broader Bragg peak than the raw beam. A 1.3 ± 0.1 MeV FWHM peak width in the energy distribution was used in the simulation to match the Bragg peak width. An additional 1.3-2.24 mm of water in the water column was required over the nominal values to match the measured depth penetration. The proton Bragg curve measured for the 0.1016 mm thick Ta foil provided the most accurate benchmark, having a low contribution of proton scatter from upstream of the water tank. The accuracy was 0.15% in measured beam energy and 0.3% in measured depth penetration at the Bragg peak. The depth of the distal edge of the Bragg peak in the simulation fell short of measurement, suggesting that the mean ionization potential of water is 2-5 eV higher than the 78 eV used in the stopping power calculation for the simulation. The eye treatment beam line depth dose curves provide validation of Monte Carlo simulation of a Bragg curve and SOBP with 4%/2 mm accuracy.

Saccharum spontaneum L. ssp. aegyptiacum (Willd.) Hack. a potential perennial grass for biomass production in marginal land in semi-arid Mediterranean environment

Research is needed to look for plants or lines that can thrive on soils affected by water deficit or other constraints. The present work investigated the potentiality of Saccharum spontaneum L. spp. aegyptiacum (Willd.) Hack., a lignocellulosic, perennial, rhizomatous, no-food crop in semi-arid Mediterranean area. A 3-year field trial was carried out with the aim to evaluate its physiology, biomass yield, water use efficiency, and biomass quality under different soil water availability. During 2011/2012, 2012/2013, and 2013/2014 growing seasons (hereinafter referred as 2011, 2012, and 2013, respectively), three levels of maximum evapotranspiration restitution (ETm) were compared: I100 (100% ETm restitution), I50 (50% ETm restitution), and I0 (rainfed condition).Net photosynthesis, stomatal conductance, and transpiration rate were strictly related to the available soil water content (ASWC), with maximum gas exchange at field capacity. However, gas exchange between plants and atmosphere was also measured when ASWC was close to wilting point.Biomass dry matter (DM) yield and main morpho-biometric traits (e.g., stem height and basal stem diameter) were significantly affected by ASWC. A non-linear model showed that maximum DM yield, 37.86Mgha−1, can be achieved when 1150mm of water were used by the crop. Water use efficiency (WUE) was always highest in rainfed condition (I0), however, only in 2013 I0 was significantly higher than I50 and I100 (5.89gL−1 vs 4.26 and 3.33gL−1). Within the variables employed, a linear model showed that WUE was negatively related to crop water use (CWU).The fiber content was not affected by the irrigation treatments. In the average, hemicellulose, cellulose, and lignin accounted for 23.9 (% w/w), 35.0 (% w/w), and 19.9 (% w/w), respectively. On the other hand, moisture and ash content, bulk density, low heating value, and ash melting point resulted significantly affected by the treatment.Present results suggested that S. spontaneum spp. aegyptiacum possesses a range of agronomically desirable traits of biomass crop: C4 plant, high biomass yield, active assimilation rates during drought–stress periods, able to use water efficiently, and satisfactory biomass quality.

Response of Orange Trees to Deficit Irrigation Strategies: Effects on Plant Nutrition, Yield, and Fruit Quality

AbstractEnvironmental and economic sustainability of agricultural systems has to face the general decreasing trend of water resources through the adoption of strategies aimed at improving water-use efficiency. In the study, during three consecutive summer seasons, the effects of deficit irrigation (DI) treatments applied on mature orange trees [Citrus sinensis (L.) Osbeck] cv. “Tarocco Meli” were analyzed. Two different DI strategies supplying 70 and 50% of crop evapotranspiration (ETc) were compared with irrigation at the full rate of ETc; the comparisons were carried out in terms of plant physiological response, crop production, quality, and nutritional status. The orange trees became less sensitive to moderate water restrictions (DI = 70% ETc) permitting approximately 80 mm of water saving (i.e., corresponding to a threshold for water stress integral of 60 MPa) per season without any significant impact on their water status and on agronomic performances. Severe water restrictions (DI=50% ETc) reduced f...

Bulk Scale Synthesis of Monodisperse PDMS Droplets above 3 μm and Their Encapsulation by Elastic Shells

We report several facile, surfactant-free methods to prepare monodisperse polydimethylsiloxane (PDMS) droplets in the size range 3–8 μm in water. These methods, of which the pros and cons are discussed, are extensions of a procedure described before by our group which focused on smaller droplet sizes. The PDMS oil droplets are formed by ammonia catalyzed hydrolysis and condensation of the monomer dimethyldiethoxysilane (DMDES) in water. One of the methods entails a seeded growth procedure in which other oils, such as lower molecular weight hydrocarbons, were found to be able to swell the PDMS droplets if their solubility in water was higher than that of the seed droplets. This way, larger droplets with mixed composition could be prepared. It also turned out to be possible to load the monodisperse droplets with an oil soluble dye. The droplets could be coated with an elastic, partially permeable, shell formed by cross-linking the PDMS with tetraethoxysilane (TES) in the presence of poly(vinylpyrrolidone) (PVP) that provided colloidal stability. Besides, the liquid interior of these shells could be changed by solvent exchange.