热泵干燥北极虾的物理和感观特性研究

对分别在(-2～0)℃和20℃两种温度下热泵干燥北极虾(整虾、去头北极虾、去壳北极虾)的物理和感官特性进行了研究.结果显示,当热泵干燥温度由(-2～0)℃增加到20℃时,干燥虾的收缩率和所需的剪切力增大.干燥温度对干燥虾的色泽影响不显著.所有热泵干燥虾均具有高的复水能力和水分保持能力(WHC).研究结果还显示,虾的处理状态(有壳或无壳、有头或无头、解冻处理)对其物理和感官特性有着显著影响.解冻处理不利于虾色泽的保持并使之收缩增加.在所有的干燥虾样品中,在20℃下干燥的冷冻去头虾(B-2)具有最好的综合表现.与热风干燥相比,利用热泵干燥虾可获得高质量干燥产品.     

热泵干燥北极虾和鱼块的干燥特性研究(英文)

利用热泵干燥机,分别在-2～0℃和20℃两种温度下对北极虾整虾、去头北极虾、去壳北极虾和尺寸分别为50 mm(直径)×(7～9)mm(厚度)和50 mm×(14～18) mm的鱼块进行了干燥研究。结果显示,虾的状态(有壳或无壳、有头或无头)和鱼块的厚度对其干燥特性有着显著影响。无论干燥温度为-2～0℃还是20℃,去壳虾所需干燥时间均最少,去头虾的干燥速度均大于整虾;薄鱼块的干燥速度在20℃显著大于厚鱼块的干燥速度。扩散模型MR=Aexp(-kt)可以很好地描述热泵干燥北极虾和鱼块的干燥特性,根据试验结果建立的一系列统计回归模型显示,当热泵干燥温度由-2～0℃增加到20℃时,干燥速度和K值显著增加,干燥时间明显减小。     

水流近壁面水力剪切力对滴灌系统碳酸钙污垢的影响

针对目前水动力学条件对滴灌系统碳酸钙污垢形成的影响及适宜的污垢控制阈值尚不明确的问题,该研究对不同近壁面水力剪切力（0～0.7 Pa）下的滴灌系统附着碳酸钙污垢总量、晶相组成及表观形貌进行了分析。结果表明：不同剪切力显著（P<0.05）影响了碳酸钙污垢的形成,随着剪切力的增大碳酸钙污垢的总量呈现先增高后降低的趋势,最大碳酸钙污垢形成量的剪切力为（0.42±0.02）Pa。剪切力较低（0～0.42 Pa）时,随着剪切力的增大碳酸钙晶体的尺寸逐渐变大,Ca2+和CO32-的碰撞几率增加且晶体成核效率提高,使得碳酸钙污垢总量呈现增加趋势;剪切力较高（0.42～0.7 Pa）时,随着剪切力的增大碳酸钙晶体大小逐渐减小,且晶体由于高剪切力的作用发生破碎和脱落,使得碳酸钙污垢总量呈现下降趋势。建议灌水器流道近壁面水力剪切力控制在0～0.24 Pa和0.65～0.7 Pa,以减少碳酸钙污垢的形成。本文的研究结果可为高抗堵塞灌水器的研发以及劣质水滴灌技术的应用和推广提供支撑。     

糖液与钙盐组合渗透脱水处理对冻融蓝莓品质的影响

为探究钙盐作为冷冻保护剂与高浓度糖液浸渍组合在常温下进行渗透脱水处理对冷冻蓝莓融化后质地品质的影响。对比以丙酸钙、乳酸钙、氯化钙为代表的3种钙盐冷冻保护剂及质量浓度为0.5、1.5、3.0、5.0 g/mL丙酸钙处理对冻融蓝莓品质的影响。通过观测蓝莓冻融后外观,测定硬度值、弹性、咀嚼性、胶着性、内聚性和回复性品质指标及可溶性果胶、共价结合型果胶和离子结合型果胶的含量。结果表明：添加钙盐结合糖液渗透脱水处理组均可减少蓝莓冻融后皱缩和质地瘫软现象,丙酸钙结合糖液渗透脱水处理组的汁液流失率比对照组降低约25.42%,显著低于（P＜0.05）其他处理组,丙酸钙处理组为较优的钙盐添加种类。对丙酸钙添加浓度进行优化筛选,发现当丙酸钙添加浓度为1.5 g/mL时可显著降低（ P ＜0.05）蓝莓果实的汁液流失和细胞膜透性,冻融后硬度为1.54 N、弹性0.75 mm,可溶性果胶、共价结合型果胶和离子结合型果胶含量分别达到1.03、0.83 和0.68 mg/g,减少蓝莓果实的质地瘫软现象并保持最佳冻融品质。丙酸钙浓度为1.5 g/mL结合渗透脱水技术使冻融蓝莓具有更好的品质,有利于食用和加工。研究结果不仅为解决蓝莓加工行业出现的由于长期冷冻所造成果实质地瘫软问题提供数据基础,还为研发提升果蔬原料冷冻贮藏品质的助冻剂及改性技术提供一定的理论依据。     

样本预处理方式对罗氏沼虾碳和氮稳定同位素比值检测的影响

为研究样本预处理方式对罗氏沼虾碳和氮稳定同位素比值检测的影响,分别选用3种保存温度(常温23℃/15 d、冷藏2℃/90 d、冷冻-18℃/360 d)、2种取样方式(虾仁取样、整虾取样),以新鲜沼虾样本为对照组,对比不同样本预处理方式对罗氏沼虾碳稳定同位素比值(δ¹³C)、氮稳定同位素比值(δ¹⁵N)、碳氮比(C/N)的影响。结果表明,不同保存温度和不同取样方式对罗氏沼虾δ¹³C、δ¹⁵N、C/N的影响明显。与对照组相比,常温保存条件下的δ¹⁵N偏移量最大(1.31‰~13.16‰,平均值为6.02‰),冷冻保存条件下的δ¹³C偏移量最大(2.34‰~2.84‰,平均值为2.57‰),室温保存条件下的C/N显著增加(P<0.05),冷藏和冷冻保存条件下的C/N显著减少(P<0.05)。不同取样方式对罗氏沼虾δ¹⁵N、δ¹³C的影响还取决于保存温度,在冷冻保存条件下,整虾取样的δ¹⁵N、δ¹³C显著高于虾仁取样,而在常温保存条件下,整虾取样的δ¹⁵N偏移量显著低于虾仁取样。因此,常温(23℃)和冷藏(2℃)条件不适合保存罗氏沼虾、冷冻(-18℃)保存罗氏沼虾的时间不宜超过60 d,建议新鲜沼虾采集后应立即干燥并开展碳和氮稳定同位素检测。本研究结果为水产品碳和氮稳定同位素比值检测的样本预处理方式提供了参考。     

Physicochemical properties and method for determination of potassium guaiacolsulfonate

The physicochemical properties of potassium guaiacol-4-sulfonate (I) and -5-sulfonate (II) have been investigated. Analyses of the X-ray diffraction patterns, infrared spectra, and thermogravimetric and differential scanning calorimetric curves showed that I occurs as crystals that are anhydrous or hydrated up to 2/3 mole (4.8%) and that II occurs as crystals that are anhydrous or dihydrated (13.5%). Solutions of I and II at various pH values showed almost the same UV spectra at less than pH 6.0 but very different UV spectra greater than pH 7.0. Most commercially available potassium guaiacolsulfonate consists predominantly of potassium guaiacol-4-sulfonate (as determined by UV-absorption measurements and liquid chromatography).     

采用主成分分析抗冻剂对冷冻虾肉糜3D可打印性的影响

针对冷冻虾肉糜的蛋白质易发生冷冻变性而失去3D可打印性的问题,该研究以添加不同抗冻剂的虾肉糜为研究对象,对虾肉糜冷冻贮藏过程中3D打印精确性和稳定性、流变和质构特性的变化开展试验研究,采用相关性和主成分分析虾肉糜3D打印精确性和稳定性与流变和质构特性之间的关系。研究结果表明,随着冻藏天数的延长,所有处理虾肉糜的3D打印精确性和稳定性、黏性常数、流变单元之间的连接强度、硬度、弹性、黏附性、持水性等均呈下降趋势;添加抗冻剂的处理可以减缓虾肉糜这些指标的下降;3D打印精确性和稳定性与虾肉糜的黏性常数、流变单元之间的连接强度、弹性、硬度、黏附性、持水性等呈正相关。添加8%海藻糖+0.3%多聚磷酸盐（即TP处理）抑制虾肉糜肌原纤维蛋白冷冻变性的效果最好,冻藏30 d后虾肉糜仍具有较好的3D可打印性,打印精确性和稳定性分别为96.64%和97.61%,该研究结果为保障虾肉糜3D打印的原料供应提供了理论参考。     

Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit

The ellagic acid, total phenolic, and vitamin C contents in four raspberry cultivars (Heritage, Autumn Bliss, Rubi, and Zeva) grown in Spain were detected and quantified by HPLC in fresh, just frozen, and stored fruits at -20 degrees C for a one year period. Ellagic acid [207-244 mg kg(-)(1) of fresh weight (fw)], total phenolic (137-1776 mg kg(-)(1) of fw), and vitamin C (221-312 mg kg(-)(1) of fw) contents in raw material were higher in the late cultivars Zeva and Rubi than in the early cultivars Autumn Bliss and Heritage. The freezing process slightly affected the values of extracted ellagic acid, total phenolic, and vitamin C content. At the end of long-term frozen storage (12 months), no significant change of total phenolic content extracted was observed, but significant decreases of 14-21% in ellagic acid and of 33-55% in vitamin C were quantified. Free radical scavenging capacity measured as antiradical efficiency (AE) depends on the seasonal period of harvest. Late cultivars, Rubi (6.1 x 10(-)(4)) and Zeva (10.17 x 10(-)(4)), showed higher AE than early cultivars, Heritage (4.02 x 10(-)(4)) and Autumn Bliss (4.36 x 10(-)(4)). The freezing process produced a decrease of AE values in the four cultivars ranging between 4 and 26%. During the frozen storage, the AE values reached after the freezing process remained unchanged.     

Incorporation of Chromate into Calcium Carbonate Structure During Coprecipitation

To rigorously assess treatment technologies and establish regulatory framework for chromate-contaminated site remediation, it is useful to know the exact chromium speciation in soil matrices. In an earlier study, Thornton, E. C., & Amonette, J. E. (1999). Hydrogen sulfide gas treatment of Cr(VI)-contaminated sediment samples from a plating-waste disposal site – implications for in-situ remediation. Environmental Science & Technology, 33, 4096–4101, reported that some chromate in the bulk particles was not accessible to gaseous reductants or solution-phase extractants, based on XANES studies. We hypothesized that part of this non-extractable chromate may reside in the structure of minerals such as calcium carbonate. To test this hypothesis, a number of calcium carbonate precipitates were prepared in the presence of various concentrations of chromate during the precipitation, which could coprecipitate chromate, or by adding chromate after the precipitation was completed. Hydrochloric acid was used to dissolve calcium carbonate and therefore extract the coprecipitated and surface attached chromate. The results showed that the coprecipitated chromate was non-extractable by hot alkaline solution or phosphate buffer, but could be solubilized by HCl in proportional to the amount of calcium carbonate dissolved. The X-ray diffraction experiments revealed that the coprecipitation of chromate with calcium carbonate had an influence on its crystal structure: The higher the chromate concentration, the greater the ratio of vaterite to calcite.     

Optimizing Adsorption of Co(II) and Ni(II) by 13× Molecular Sieves Using Response Surface Methodology

Batch experiments were carried out to investigate the adsorption characteristics of Co(II) and Ni(II) by 13× molecular sieves which are hydrothermally synthetic byproducts accompanied with preparation of potassium carbonate from insoluble potash ores. The response surface methodology technique was utilized to optimize the process conditions. The combined effects of the major parameters including pH, initial concentration of metal ions, and temperature on the adsorption were investigated using central composite design. The analysis of variance of the quadratic model suggested that the predicted values were in good agreement with experimental data. The optimum conditions were found to be: initial concentration of metal ions, 20?mg/L; temperature 40?°C for both the metals; and pH, 6.29 and 8.0 for Co(II) and Ni(II), respectively. Scanning electron microscope and X-ray diffraction analyses testified to the obvious change of the surface morphology and the presence of metal on the sorbent after adsorption. The results from the sequential adsorption?Cdesorption cycles showed that 13× molecular sieves adsorbent held good desorption and reusability.     

VARIABLE ATMOSPHERE DTA IN IDENTIFICATION AND DETERMINATION OF ANHYDROUS CARBONATE MINERALS IN SOILS

The value of modem commercial DTA equipment in the identification and determination of anhydrous carbonate minerals can be greatly improved by incorporating a controlled-atmosphere (carbon dioxide) technique. The unproved peak definition and increased height enables the detection of carbonate minerals at concentrations of the order of 0.25 per cent by weight in a 50 mg sample. Further, the related changes in temperature of the decomposition reaction peaks provide additional information for the identification of carbonate mineral reactions. The method has particular application in mineralogical and pedological investigations.     

Radiosensitivity Studies and Radiostability of Ribulose-1,5 Bis-Carboxylase and Gas Exchange Characteristics in Wheat, Garden Pea, Field Pea, Spinach, and Okra

Implication of ureolytic biocalcification process as an efficient carbon dioxide sequestration technology was evaluated with Bacillus megaterium culture growing in a closed environment system. In three experimental sets containing either 35 % v/v CO₂ in headspace (set 1) or 50 mM urea in solution (set 3) or both (set 2), change in headspace CO₂, soluble calcium, and pH were monitored during 8 days of incubation. In absence of urea, headspace CO₂ content continued to increase in set 1 (up to 48 % v/v) without any carbonate precipitation. However, carbonate precipitation were obvious in urea containing sets (sets 2 and 3) utilizing all the added calcium (25 mM) in just 2 and 6 days, respectively. No headspace CO₂ could be detected in set 2 at the end of experimental period, and analysis suggested that this was majorly (>53 %) attributed to the solubility trapping phenomenon. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis revealed that the precipitates were made up of calcite and major fraction of vaterite polymorph of CaCO₃.     

Influence of phosphate on cadmium sorption by calcium carbonate

Laboratory investigation was conducted to investigate the mechanism of cadmium sorption by pure calcium carbonate and to examine whether, reaction products of phosphate with calcium carbonate serve as a sink for sorption of toxic heavy metal cations like cadmium. The phosphatization of calcium carbonate (G.R) was carried out by treating it with orthophosphoric acid in Ca:P ratio of 5:3, 3:2, 4:3 and 1:1, representing the Ca–P ratios of carbonate apatite, tricalcium phosphate, octacalcium phosphate and dicalcium phosphate and then equilibrated for two months. The X-ray diffraction of the phosphate reaction products revealed that calcite along with monetite, brushite and carbonate apatite were present in each case. The cadmium was effectively retained on CaCO₃ by the mechanism of chemisorption at lower Cd²⁺ concentrations as the pH of the equilibrium system remained constant (8.6) up to initial Cd²⁺ concentrations of 10⁻⁴ mol, coinciding to 100% sorption of Cd²⁺ from the solution. At higher concentrations, precipitation of CdCO₃ on CaCO₃ surface or as a separate phase predominated. Enrichment of CaCO₃ with P reduced the Cd-sorption. The chemisorption of Cd probably involved the exchange of Ca²⁺ by Cd²⁺ from CaCO₃ surface. The Cd²⁺ concentration in equilibrium solution followed the solubility diagram of CdCO₃ at pH ≤ 8.6, whereas the concentration of Ca²⁺ started deviating from the solubility line at pH ≤ 8.2.     

Kinetics and hydrolysis of fenamiphos, fipronil, and trifluralin in aqueous buffer solutions.

Hydrolyses of fenamiphos, fipronil, and trifluralin were studied in aqueous buffer solutions of pH 4.1, 7.1, and 9.1 at different temperatures, 5, 22 +/- 1, 32 +/- 1, and 50 +/- 1 degrees C. Fenamiphos, fipronil, and trifluralin were found to be more stable in acidic and neutral buffer solutions at temperatures of 5 and 22 +/- 1, and dissipation is rapid at 50 +/- 1 degrees C. In basic buffer and at higher temperature, degradation of fenamiphos was found to be very rapid when compared with fipronil and trifluralin. The rate constants calculated at 32 degrees C for fenamiphos were 2349.4 x 10(-)(8) (pH 4.1), 225.2 x 10(-)(8) (pH 7.1), and 30476.0 x 10(-)(8) (pH 9.1); for fipronil 1750.0 x 10(-)(8) (pH 4.1), 3103.0 x 10(-)(8) (pH 7.1), and 3883.0 x 10(-)(8) (pH 9.1); and for trifluralin 2331.0 x 10(-)(8) (pH 4.1), 2360.0 x 10(-)(8) (pH 7.1), and 3188.0 x 10(-)(8) (pH 9.1). On the basis of rate constant values, these pesticides appeared to be more susceptible to hydrolysis than synthetic organophosphorus compounds such as chlorpyriphos, diazinon, malathion, and ronnel. DT(50) values calculated at 32 degrees C were 228 (pH 4.1), 5310.24 (pH 7.1), and 37.68 (pH 9.1) h for fenamiphos; 608.6 (pH 4.1), 373.9 (pH 7.1), and 270.2 (pH 9.1) h for fipronil; and 502.1 (pH 4.1), 496.8 (pH 7.1), and 355.7 (pH 9.1) h for trifluralin.     

超高压前处理对虾仁冻藏期品质的影响

为研究超高压辅助脱壳所得到的中华管鞭虾虾仁在冻藏期的品质变化,以虾仁色泽、质构、肌原纤维蛋白相对含量、表面疏水性、总巯基相对含量和Ca²⁺-ATPase活性为指标,探讨超高压前处理对虾仁品质的影响。结果表明,冻藏6个月后虾仁L^*值、a^*值和b^*值均有所变化,与对照组相比,超高压前处理对虾仁L^*值的影响不显著,但能延缓冻藏后期a^*值的增加,对保持虾肉色泽的稳定有一定作用;超高压前处理对虾仁的咀嚼性和弹性影响不显著,但能增加虾仁的硬度。超高压前处理使冻藏初期虾仁肌原纤维蛋白的表面疏水性增加,而对其溶解性、巯基含量及Ca²⁺-ATPase活性的影响不显著;冻藏后期由于虾仁蛋白冷冻变性,致使肌原纤维蛋白溶解性、巯基含量及Ca²⁺-ATPase活性下降。综上所述,超高压辅助脱壳在一定程度上有利于保持冻虾仁的色泽和硬度。本研究结果为利用超高压技术辅助脱除中华管鞭虾虾壳,生产冷冻虾仁提供了新思路。     

Anhydrous goat's milk fat: thermal and structural behavior. 1. Crystalline forms obtained by slow cooling

The thermal and structural behaviors of anhydrous goat's milk fat (AGMF) have been determined as a function of temperature using a powerful technique allowing simultaneous time-resolved synchrotron X-ray diffraction as a function of temperature (XRDT) and high-sensivity differential scanning calorimetry (DSC) measurements from the same sample. This first paper, aiming at the characterization of the physical properties of AGMF, we examine crystalline organizations made by triacylglycerols (TG) upon slow cooling at /dT/dt/ = 0.1 degrees C/min from 45 to -20 degrees C in order to approach system equilibrium. Three overlapped exotherms were observed by DSC upon cooling, whereas four endotherms were found on the subsequent heating at 1 degrees C/min. XRDT evidenced that AGMF crystallizes under four different lamellar structures, two with double-chain length packings at 41.5 and 38.2 angstroms and two with triple-chain lengths of 72 and 64.7 angstroms stacking. Simultaneous wide-angle XRDT has shown that initial nucleation mainly occurs in a packing of beta' type from approximately 26 degrees C, although some transient presence of alpha was detected. The absence of polymorphic transition, on heating, until final melting (approximately 40 degrees C) demonstrated the relative stability of the structures formed.     

唐皇城含光门土遗址盐分病害分析与研究

唐皇城含光门土遗址中微溶-可溶盐导致地泛白、酥粉、片状脱落等病害极为严重。通过对土壤含水率、酸碱度(pH)、电导率测定以及微溶-可溶盐的X射线粉末衍射(XRD)、能谱(EDX)、扫描电子显微镜(SEM)分析,结果表明:唐皇城含光门东展厅土遗址微溶-可溶盐主要以硫酸钙类和硫酸钠类为主;西展厅五期断面土遗址主要以硫酸钙类、碳酸钙类为主。不同部位含盐量与水分的运移密切相关,随着距离水平地面高度的增加,含水率的的降低,微溶-可溶盐的含量降低。通过扫描电子显微镜观察发现,硫酸钙类是导致土遗址酥粉、脱落病害的主要原因。     

Simultaneous determination of (fluoro)quinolone antibiotics in kidney, marine products, eggs, and muscle by enzyme-linked immunosorbent assay (ELISA)

A direct competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect a broad range of (fluoro)quinolones in various matrices. In the optimized generic test, anti-sarafloxacin antibodies in combination with norfloxacin conjugate showed 50% binding inhibition at 0.21 ng mL(-)(1) for sarafloxacin in buffer. Screening for this class of antibiotics is accomplished using a simple, rapid extraction carried out with a 1:1 mixture of methanol and phosphate-buffered saline adjusted to pH 7.4. This common extraction was able to detect 15 (fluoro)quinolone residues such as sarafloxacin, norfloxacin, difloxacin, ciprofloxacin, pefloxacin, ofloxacin, cinoxacin, danofloxacin, enrofloxacin, marbofloxacin, lomefloxacin, enoxacin, flumequine, oxolinic acid, and nalidixic acid in pig kidney, poultry muscle, egg, fish, and shrimp. The assay's detection capabilities (CCbeta) for most of these compounds were <10 microg kg(-)(1) except for the sarafloxacin-, oxolinic acid-, flumequine-, and cinoxacin-spiked matrices, the estimated CCbeta values of which were <4, <25, <100, and <200 microg kg(-)(1), respectively.     

Automation of dihydroxyaluminum sodium carbonate analysis in antacid tablets by energy dispersive X-ray fluorescence

A sensitive, specific, automated energy dispersive X-ray fluorescence (EDXRF) method for determination of anhydrous dihydroxyaluminum sodium carbonate in antacid tablets has been developed. The compound was quantitated by impact grinding, pelletizing at 10 tons pressure, and monitoring the aluminum by using a rhodium anode X-ray tube, high resolution thermoelectrically cooled Si(Li) detector with sample spinning, and computer data processing. The assay procedure was validated with spiked laboratory-prepared samples at 100 +/- 20% levels. The average recovery was 100.6% with a relative standard deviation of 1.6% (n = 14). Instrument precision was determined and found to have an average relative standard deviation of 1.0% (n = 16). In addition, analysis precision by the EDXRF method was compared to that for titration and autoanalyzer methodologies and found to be statistically comparable. The sample precision had an averaged relative standard deviation of 2.7% (n = 16) by X-ray methodology. The advantages of this EDXRF method include increased sample throughout with excellent precision and accuracy, no solvent usage, and automated data handling.     

四种土壤调理剂对镉、铅的吸附效果研究

采用等温吸附试验研究了主要原料为麦饭石(M)、蒙脱石(T)、牡蛎壳(O)和硅钙矿(S)4种土壤调理剂对溶液中镉和铅的吸附效果。结果表明,4种土壤调理剂对镉和铅的吸附均可用Langmuir方程进行描述;相比而言,4种土壤调理剂对镉吸附量的大小顺序为O调理剂>S调理剂>M调理剂>T调理剂,对铅吸附量的大小顺序为M调理剂>S调理剂>O调理剂>T调理剂;随溶液pH值的增大各调理剂的吸附量逐渐减小,尤其当Cd溶液pH值>8,Pb溶液pH值>6,各调理剂的吸附量迅速降低。