Optimization of extraction of phenolic compounds from flax shives by pressurized low-polarity water

Pressurized low-polarity water (PLPW) extraction of phenolic compounds from flax shive was investigated using statistically based optimization and the "one-factor-at-a-time" method. Extraction variables examined using central composite design (CCD) included temperature, flow rate, and NaOH concentration of the extracting water. Extraction of phenolic compounds including p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, acetovanillone, and feruric acid was affected by temperature and NaOH concentration; and extraction of all phenolic compounds, except ferulic acid, increased with temperature and NaOH concentration of the extracting water. Flow rate had little effect on concentration of phenolic compounds at equilibrium, but the extraction rate at the early phase was higher for higher flow rates. The mechanism of PLPW extraction of flax shive phenolics was also investigated using a two-site kinetic model and a thermodynamic model. To determine the extraction mechanism, flow rate was varied from 0.3 to 4.0 mL/min while temperature and NaOH concentration were fixed at 180 degrees C and 0.47 M, respectively. The flow rate tests showed the extraction rates of total phenolic (TP) compounds increased with flow rate and can be described by a thermodynamic model. The results from the thermodynamic model demonstrated that a K(D) value of 30 agreed with the experimental data in the flow rate range of 0.3-4.0 mL/min. When the effect of the three independent variables was evaluated simultaneously using CCD, a maximum TP concentration of 5.8 g/kg of dry flax shive (DFS) was predicted from the combination of a high temperature (230.5 degrees C), a high initial concentration of NaOH (0.63 M), and a low flow rate (0.7 mL/min). Maximum TP concentration of 5.7 g/kg of DFS was obtained from extraction conditions of 180 degrees C, 0.3 or 0.5 mL/min, and 0.47 M NaOH at equilibrium. A second-order regression model generated by CCD predicted a maximum TP concentration of 5.8 g/kg of DFS under the same extraction conditions, which is well matched with the results from experimental data.     

Structural characterization of guaiacyl-rich lignins in flax (Linum usitatissimum) fibers and shives

The structural characteristics of the lignins from flax (Linum usitatissimum) fibers and shives were studied. Significant differences in the content and composition of the lignin from both parts were observed. The lignin contents were 3.8% in the fibers and 29.0% in the shives. Analysis by Py-GC/MS indicated a H:G:S molar ratio of 13:72:15 in the milled wood lignin (MWL) isolated from flax fibers and a molar ratio of 5:87:8 in the MWL isolated from flax shives. In addition, 2D-NMR showed a predominance of β-O-4' aryl ether linkages, followed by β-5' phenylcoumaran and β-β' resinol-type linkages in both MWLs, with a higher content of condensed linkages in flax shives. Thioacidolysis (followed by Raney nickel desulfurization) gave further information on the lignin units involved in the different linkages and confirmed the enrichment of G units. The thioacidolysis dimers released were similar from both lignins, with a predominance of the β-5' followed by β-1' and 5-5' structures.     

Absorption of ammonia from atmospheric plumes by natural water surfaces

A simple model is presented that incorporates the major features of atmospheric transport and diffusion of a NH₃ plume together with aqueous absorption as the plume traverses a water surface. The model is based on the well-known concept of the deposition velocity, although empirical data concerning the latter is quite meager. A specific application is considered to the gas release from a NH₃ stripper of a hypothetical sewage treatment plant, and it is concluded that NH₃ absorption by adjacent water masses could be considerable.     

低温工厂化养殖水体氨氮处理微生物的初步研究

为了研究低温环境下工厂化养殖水体氨氮处理微生物，用平板菌落计数法和最大几率数法对处理养殖水体的生物滤池中的微生物数量进行了跟踪检测，同时测定实验组和对照组养殖水体的理化性质。结果显示在实验过程中，硝化细菌和亚硝化细菌的数量持续上升，后期达到稳定；初期系统中没有反硝化细菌，后期数量开始逐渐增加。实验组与对照组的养殖水体的氨氮、硝酸盐和亚硝酸盐浓度的测定结果证明了生物滤池中的硝化——反硝化系统在发挥作用。实验表明经过低温环境的驯化和诱导，在12℃的低温条件下，微生物处理仍然是工厂化养殖水体中氨氮的有效处理手段。实验验证了在冷水鱼工厂化低温养殖中使用生物滤池处理氨氮的可行性。     

Structural and thermal characterization of wheat straw pretreated with aqueous ammonia soaking

Production of renewable fuels and chemicals from lignocellulosic feedstocks requires an efficient pretreatment technology to allow ready access of polysaccharides for cellulolytic enzymes during saccharification. The effect of pretreatment on wheat straw through a low-temperature and low-pressure soaking aqueous ammonia (SAA) process was investigated in this study using Fourier transform infrared (FTIR), pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS), solid and liquid state nuclear magnetic resonance (NMR), and thermogravimetry/differential thermogravimetry (TG/DTG) to demonstrate the changes in lignin, hemicellulose, and cellulose structure. After treatment of 60 mesh wheat straw particles for 60 h with 28-30% ammonium hydroxide (1:10 solid/liquid) at 50 °C, sugar recovery increased from 14% (untreated) to 67% (SAA treated). The FTIR study revealed a substantial decrease in absorbance of lignin peaks. Solid and liquid state NMR showed minimal lignin structural changes with significant compositional changes. Activation energy of control and pretreated wheat straw was calculated according to the Friedman and ASTM methods and found to be decreased for SAA-treated wheat straw, from 259 to 223 kJ/mol. The SAA treatment was shown to remove significant amounts of lignin without strongly affecting lignin functional groups or structure.     

稻田氨挥发损失和水稻产量对不同水氮处理的响应

为了实现减少氨挥发带来的环境负效应和增加作物产量的目的,在典型的江汉平原稻作区,设计4种不同的水氮管理模式:1)U+CI(普通尿素+常规灌溉),对照(CK);2)US+SWD(普通尿素减氮20%+薄浅湿晒节水灌溉);3)CRU+CI(树脂包膜控释尿素+常规灌溉);4)CRUS+SWD(树脂包膜控释尿素减氮20%+薄浅湿晒节水灌溉),探究了减氮与节水灌溉搭配的条件下,控释尿素对稻田氨挥发损失和水稻产量的影响。结果表明:不同水氮处理间稻田土壤铵态氮浓度无显著差异,但在水稻不同生育期间差异显著,表现为返青期分蘖期、孕穗期、抽穗期成熟期;各水氮处理氨挥发最高峰出现在施肥后的1～3 d,其中CRU+CI的氨挥发速率最快,为N 1.46 kg·hm~(-2)·d~(-1)。在整个晚稻生长季,基肥期和分蘖期是氨挥发的主要时期;节水减氮搭配下,常规施肥稻田的氨挥发总量显著小于控释肥处理稻田的氨挥发总量。其中US+SWD分别比CRU+CI和CRUS+SWD氨挥发总量降低了21.3%和15.3%,损失率分别降低了0.9%和14.8%;其中U+CI的氨挥发总量分别比CRU+CI和CRUS+SWD的氨挥发总量降低了15.7%和9.4%,损失率分别降低了15.5%和27.3%。稻田氨挥发损失量与土壤铵态氮浓度显著正相关。相比U+CI(CK),CRU+CI的水稻产量和CRUS+SWD的水稻产量均显著增加,其中CRU+CI增加了17.4%,CRUS+SWD增加了11.0%,而两个处理之间的水稻产量没有显著差异。因此,综合增产效应和节能减排效应,CRUS+SWD是该区域目前最佳的水肥管理方式。     

Oxidation of carbaryl in aqueous solution by membrane anodic fenton treatment

Carbaryl, a commonly used insecticide, was used in this study as a probe to investigate a new Fenton treatment technology, ion exchange membrane anodic Fenton treatment (membrane AFT). It was found that the degradation kinetics of carbaryl by membrane AFT obeys a previously published AFT model quite well. The NaCl (electrolyte) concentration in two half-cells was optimized for two kinds of membrane. Effects of the H(2)O(2)/Fe(2+) ratio and the Fenton reagent delivery rate were also investigated. The treatment efficiency for anion membrane AFT is higher than for salt-bridge AFT under the same operating conditions. Decreasing the delivery rate of Fenton reagents and increasing the treatment temperature also increase the treatment efficiency. The activation energy for carbaryl degradation by anion membrane AFT was estimated to be 14.7 kJ x mol(-1). 1-Naphthol, 1,4-naphthoquinone, and (phthalic acid-O-)yl N-methylcarbamate were detected by GC-MS as the degradation products of carbaryl by Fenton treatment. No decrease in carbaryl degradation rate was found during repeated use (100 times) of the anion exchange membrane. High and stable treatment efficiency can be achieved using an anion exchange membrane rather than a salt-bridge in the AFT system. Because of its effectiveness and convenience, the use of an ion exchange membrane as a substitute for the salt-bridge used in the previous AFT system has brought the AFT technology a major step closer to practical application.     

Fractionation of dissolved organic carbon in soil water: Effects of extraction and storage methods

Abstract

We measured the concentration and composition (sensu Leenheer, 1981) of dissolved organic carbon (DOC) in lysimeter solutions from the forest floor of a spruce stand in Maine and in laboratory extracts of organic (Oa horizon) and mineral soils collected from various forests in Maine, New Hampshire, and Vermont. All soils were acid Spodosols developed from glacial till. The effects of different storage, extraction and filtration methods were compared. Extracts from Oa horizons stored fresh at 3°C contained a larger fraction of hydrophobic neutrals than lysimeter forest floor solutions (31 and 4% of DOC in stored and lysimeter solutions, respectively), whereas extracts from Oa horizons which had been extracted, incubated at 10–15°C, and extracted again had DOC compositions similar to that in lysimeter solutions. Mechanical vacuum and batch extractions of Oa horizons yielded DOC similar in concentration and composition if the extracts were filtered through glass fiber filters. Nylon membrane filters, however, removed more hydrophobic acids from batch extracts. Dissolved organic carbon extracted from frozen, air‐dry, and oven‐dry Oa and Bh horizons was relatively rich in hydrophilic bases and neutrals and was similar to that released after chloroform fumigation, indicating that common soil‐storage methods disrupt microbial biomass.     

Evidence for effects of CO2 on soil solution chemistry in spodosols by a simple in-field extractor

Degassing of CO₂ during collection of soil solution may alter the chemical composition of the solution, especially in well-buffered soils. We used a simple syringe extractor for field sampling of soil solution along with ambient soil air in order to test the influence of degassing of CO₂ on solution pH in acid soils (Spodosol B and C horizons collected in Central Maine, USA). Soil air concentrations of CO₂ varied from 0.36 to 1.35 ml l-¹ during sampling immediately after snow melt. Degassing increased solution pH by 0.3 to 0.5 pH units. Both in-situ and degassed pH were predicted by the Reuss and Johnson soil chemical equilibrium model. The results suggest, (i) that the simple method is useful for determination of solution from wet soil under ambient soil air conditions and (ii) that degassing plays a significant role for soil solution chemistry even in Spodosol B and C horizons.     

Analysis of fiber content in flax stems by near-infrared spectroscopy

The conventional means of measuring the fiber content of flax is time-consuming and laborious, and the results obtained vary with the analysis technique used. The plant tissues must first be "retted", a process by which the fibers are separated from the rest of the stem, either by indigenous organisms in the soil when the stems are left in the field or by water (anerobic bacteria) or enzymatic retting. The fiber content is then determined by mechanical or manual separation. In this study, fiber content of flax stems was measured rapidly and objectively by near-infrared spectroscopy (NIRS) using whole pieces of stem in a large cell, in reflectance mode. Compared to the conventional method, the standard error of performance of the NIRS method was between 0.96 and 1.45% (dry matter basis), depending on the model and data processing used. NIRS calibrations were generated by hand separation of fiber from water-retted specimens. The water retting procedure takes several days to complete and requires considerable trained labor to complete the hand separation step. The NIRS procedure was conducted on pieces of stem to simulate measurement in the field.     

Fractionation of organo-mineral complexes by sedimentation and density techniques

Soil samples were fractionated by sedimentation in water and by flotation in heavy liquids to separate complexed and uncomplexed organic and inorganic components. Flocculation of clays in heavy organic liquids was delayed by addition of a surfactant. Heavy liquids and surfactants sorbed by soil components were removed by washing with acetone-water mixtures.In a sample of a red-brown earth, the organic carbon and nitrogen contents were highest in the finest separates. In samples of a ground-water rendzina and a chernozemic soil, the coarse clay and silt separates had the highest organic carbon and nitrogen contents. Organic matter was concentrated in low density fractions in all separates. Carbon/nitrogen ratios were lowest in the finer and heavier separates. Calcium, and to a lesser extent manganese, iron and phosphorus, were concentrated in low density fractions: thus these elements appear to be associated with organic matter and may be important in organo-mineral complex formation. Carbonates, titanium, iron, silicon and potassium were concentrated at the highest densities.Organic fractions < 2.06 g cm^?3 from sand size separates were insoluble in alkali and had wide carbon/nitrogen ratios characteristic of plant debris. The light fractions from fine silt and coarse clay separates were more soluble in alkali but showed high ratios of humic to fulvic materials and high absorption at 280 nm. Such materials were considered to be microbial cell debris and were associated with high contents of disordered aluminium and iron oxides and expanding lattice silicates in 1 to 5 μm aggregates.Heavier fractions, particularly of finer clay separates, contained more fulvic and humic materials of a more aliphatic nature than those in < 2.06 g cm^?3 fractions. It is suggested that physical sorption on clay surfaces may be more important in these fractions. Ellite and kaolinite were concentrated in medium density fractions, and contents of some iron oxides and titanium minerals were highest in fractions > 2.06 g cm^?3. Such minerals plus quartz and feldspars were associated with minor amounts of organic matter or possibly were not involved in organo-mineral associations.     

Fractionation of selenium and detection of selenomethionine in a soil extract

Abstract

A procedure is described to fractionate, identify and quantify organic selenium compounds at μg/kg levels in soil extracts. The fractionation is based first on the different solubility of humates and fulvates at low pH, followed by adsorption chromatography with XAD‐8 resin. The latter uses a pH gradient to elute the acidic and basic hydrophobic fulvates as well as hydrophilic fulvates. The neutral hydrophobic fulvates were retained on the column and determined by difference from the total extractable selenium. A 0.1MNaOH/0.1 M Na₄P₂O₇solution extracted 33% of the total soil selenium. In the soil studied, organic selenium was 20% of total extractable selenium. One of the hydrophilic fulvates has been identified as selenomethionine by gas chromatography‐mass spectrometry. The quantity of organic selenium and the presence of selenomethionine suggests that organoselenium compounds could be an important source of plant available selenium     

Fractionation of bagasse into cellulose, hemicelluloses, and lignin with ionic liquid treatment followed by alkaline extraction

Lignocellulose materials are potentially valuable resources for transformation into biofuels and bioproducts. However, their complicated structures make it difficult to fractionate them into cellulose, hemicelluloses, and lignin, which limits their utilization and economical conversion into value-added products. This study proposes a novel and feasible fractionation method based on complete dissolution of bagasse in 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl) followed by precipitation in acetone/water (9:1, v/v) and extraction with 3% NaOH solution. The ionic liquid [C(4)mim]Cl was easily recycled after concentration and treatment with acetonitrile. (1)H NMR analysis confirmed that there was no obvious difference between the recycled [C(4)mim]Cl and fresh material. Bagasse was fractionated with this method to 36.78% cellulose, 26.04% hemicelluloses, and 10.51% lignin, accounting for 47.17 and 33.85% of the original polysaccharides and 54.62% of the original lignin, respectively. The physicochemical properties of the isolated fractions were characterized by chemical analysis, high-performance anion exchange chromatography (HPAEC), gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), and (1)H and 2D (13)C-(1)H correlation (HSQC) nuclear magnetic resonance spectroscopy. The results showed that the acetone-soluble lignin and alkaline lignin fractions had structures similar to those of milled wood lignin (MWL). The easy extraction of the noncellulose components from homogeneous bagasse solution and amorphous regenerated materials resulted in the relatively high purity of cellulosic fraction (>92%). The hemicellulosic fraction was mainly 4-O-methyl-D-glucuronoxylans with some α-L-arabinofuranosyl units substituted at C-2 and C-3.     

Accumulation and Fractionation of Rare Earth Elements in a Soil-Wheat System

Time series bioaccumulation of rare earth elements (REEs) in field-grown wheat with and without a dressing of extraneous REE fertilizer at different growth stages and fractionation of REEs during their transport in a soil-wheat system were determined. Time-dependent accumulation of extraneous REEs was found in different parts of wheat. An upward transport of extraneous REEs from roots to shoots under a soil dressing and a downward transport from leaves to roots with a foliar dressing were also observed. Moreover, fractionation of REEs occurred in the soil-wheat system. Compared to the host soil a positive Eu anomaly in the stems and grains as well as heavy REE enrichment in the grains were found. The ability of the different wheat organs to fractionate Eu from the REE series was ranked in the order of stems ≥ grains > leaves > roots.     

规模化猪场机械通风水冲粪式栏舍夏季氨日排放特征

选取长三角地区典型机械通风水冲粪模式养猪场,针对不同生长阶段的肥猪栏舍和不同类型的母猪栏舍排放口氨排放进行同时监测(其中,育肥猪按质量分保育(24 kg)、育肥-Ⅰ(24~60 kg)、育肥-Ⅱ(60~120 kg)3个阶段,母猪分为妊娠猪与分娩猪2种类型),估算各栏舍氨排放通量,分析各栏舍氨排放特征,探讨各生长阶段对氨排放贡献。研究结果表明,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩栏舍氨质量浓度分别为(0.97±0.40)、(3.37±0.70)、(5.45±2.30)、(2.19±1.06)、(1.44±0.48)mg/m3;各栏舍氨排放具有显著的日变化过程,早晨氨排放呈波动增大趋势,午后开始降低,至夜间保持低值排放;小时氨排放速率与温度呈极显著正相关,与湿度呈显著负相关;各生长阶段氨排放存在差异,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩栏舍日排放速率分别为0.85、6.53、8.20、10.39和13.86 g/(头·d);保育、育肥-Ⅰ和育肥-Ⅱ阶段对肥猪氨排放的贡献率分别为3.64%、26.11%和70.25%,妊娠猪与分娩猪对母猪氨的贡献率分别为75.32%和24.68%,母猪的氨排放速率是肥猪的1.87倍。     

甘蔗收割机排杂风机叶轮结构参数优化与试验

切断式甘蔗收割机排杂风机的作业质量对甘蔗的含杂率有重要影响.为提高排杂风机叶轮的性能,该研究首先针对排杂风机建立了计算流体力学模型,以叶片安装角(β)、叶片数(N)、间隙占比(G)为因素,以风机转速为1650 r/min时的空载风速为指标,设计了三因素三水平的Box-Behnken仿真试验,并对叶轮参数进行优化.结果表...     

农田旧膜再利用方式对胡麻生理指标及产量的影响

为探讨全膜覆盖农田旧膜再利用的有效方式,寻求有利于胡麻高产、稳产的栽培途径,采用田间试验方法,以当年全膜覆盖作物收获后收除旧膜、翌年整地播种(无覆膜)(T6)为对照,比较了旧膜留至翌年免耕播种(T1)、在旧膜上覆土免耕播种(T2)、播种前收除旧膜并覆盖新膜免耕播种(T4)以及当年作物收获后在旧膜上覆盖玉米秸秆、翌年除去秸秆免耕播种(T3)和当年收除旧膜并整地覆盖新膜、翌年播种(T5)等5种农田旧膜再利用方式对胡麻叶片超氧化物歧化酶(SOD)活性和丙二醛(MDA)、可溶性蛋白、脯氨酸(Pro)含量以及胡麻产量及其构成因子的影响。结果表明:全膜覆盖作物收获后旧膜继续留至翌年,仍具有一定的地膜覆盖所具有的提高温度、保护土壤墒情、增强土壤养分供应能力等作用,有利于胡麻叶片SOD活性、可溶性蛋白含量的增加,协调控制叶片MDA和Pro含量,提高单株朔果数和千粒重,获得较高的单位面积产量。其中:农田旧膜留至翌年免耕直播(T1)、在旧膜上覆土免耕播种(T2)和播种前收除旧膜并覆盖新膜免耕播种(T4)3种农田旧膜再利用方式分别比对照增产10.05%、17.52%和40.67%,当年在旧膜上覆盖作物秸秆、翌年除去秸秆免耕播种(T3)和当年收除旧膜并整地覆盖新膜、翌年播种(T5)2种农田旧膜再利用方式分别比对照增产29.79%和22.16%。农田旧膜覆盖至翌年清除,而后覆盖新膜免耕直播是我国地膜覆盖种植区域农田旧膜再利用的最优方式和实现胡麻高产的最佳选择。     

Simultaneous automated determination of chloride,nitrite, nitrate,and ammonia in water and wastewater

An automated system capable of simultaneous determination of chloride, nitrite, nitrate, and ammonia in about 2 ml of fresh water or wastewater is described. The four compounds are determined using modifications of established colorimetric procedures. Results can be reported at a true rate of five samples per hour with a relative standard deviation at optimum concentrations of less than 2%. Detection limits are 1 ppm Cl for chloride and 1, 5, and 5 ppb N for nitrite, nitrate, and ammonia, respectively. Sample pH adjustment is not required from 0.0002 N H₂SO₄ (pH 3.7) to 0.005 N NaOH (pH 11.2). Fresh water and wastewater samples were analyzed for nitrite and ammonia by the proposed procedure and by the manual sulfanilic-naphthylamine and nesslerization method. Analysis by the student t-test showed no significant difference between the paired sets of data (P > 0.5). When potable and wastewater samples were spiked with sodium chloride, potassium nitrate, sodium nitrite, and ammonium chloride and analyzed, average recoveries were 99 to 103%.     

Response of ammonia oxidizing archaea and bacteria to changing water filled pore space

This study examined the effect of water filled pore space (WFPS) on gross N fluxes and community structure and abundance of ammonia oxidizing archaea and bacteria in a semi-arid soil. Different WFPS altered the community structure of both AOA and AOB. Ammonia oxidizer communities (for both archaea and bacteria) from ‘wet’ soils (95, 85 and 75% WFPS) and ‘dry’ soils (25, 45 and 55% WFPS) were distinctly different from one another. Additionally there was a significant relationship between community structure and gross rates of nitrification. There was also a significant relationship between WFPS and bacterial amoA abundance but not archaeal amoA abundance suggesting that bacterial ammonia oxidizers are more responsive to changes in soil water availability. These results are in agreement with other studies suggesting that both groups of ammonia oxidizers have distinct physiological characteristics and ecological niches with consequences for nitrification in response to WFPS. Overall findings from this study indicate that nitrification, both in terms of process rates and populations responsible for nitrification activity, is highly responsive to soil water availability.