Synthesis and characterization of ZnS:Ni-NPs loaded on AC derived from apple tree wood and their applicability for the ultrasound assisted comparative adsorption of cationic dyes based on the experimental design

The applicability of ZnS:Ni nanoparticles loaded on activated carbon derived from apple tree wood (ZnS:Ni-NPs-ACATW) for the adsorption of Methylene Blue (MB) and Janus Green B (JGB) dyes in single system from water solution has been described. The synthesized adsorbent characterized and identified by UV–Vis, FE-SEM, EDX, TEM, FTIR and XRD. The influences of operation parameters including initial MB or JGB concentration (9.0–33.0 mg L⁻¹), pH (4.0–10.0), extent of adsorbent (0.08–0.12 g) and sonication time (4.0–8.0 min) investigated and subsequently best operational condition optimized by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF) using STATISTICA 10.0 software. At optimum conditions, maximum MB and JSB adsorption onto ZnS:Ni-NPs-ACATW, i.e. 99.57% ± 1.34 and 98.70% ± 2.01, respectively was achieved pH of 7.0, 0.11 g adsorbent, 14 and 28 mg L⁻¹ of MB and JSB concentration respectively and 8 min sonication time. Experimental data were modelled by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm and monolayer adsorption capacity of MB and JSB was found to be 21.79 and 28.01 mg g⁻¹ respectively. The regression results strongly support more contribution of pseudo-second-order model for more accurate and repeatable representation of kinetic data. These results reveal that ZnS:Ni-NPs-ACATW could be useful as agents to efficiently remove dyes (JGB and MB) from contaminated water and can be very well recommended for wastewater remediation and control of environmental pollution.     

基于Slope/Bias算法的相近种类水果模型传递研究

为了提升便携式近红外仪器中单一水果模型应用的广泛性,创新性的将不同仪器间模型传递的思想应用在不同种类水果间可溶性固形物(soluble solid content,SSC)的模型传递。基于苹果、梨、桃三种水果在SSC含量范围、果型大小以及果皮厚度等的相近物理化学特性,提出利用简单的斜率/截距(Slope/Bias)算法对苹果SSC的偏最小二乘(partial least square,PLS)模型进行传递,仅用少量的梨和桃样品即可将苹果SSC模型应用于其SSC值的预测,更快捷方便且节约成本。对于梨样品,用35个标准样品,预测集均方根误差(root mean square error of prediction,RMSEP)值由直接预测的1.009°Brix降为0.565°Brix;对于桃样品,用40个标准样品,RMSEP由直接预测的1.726°Brix降为0.677°Brix。为了验证该模型传递方法的可行性,通过斜率/截距算法,采用梨和桃模型对其他两种水果的SSC进行预测,其中利用建立的梨SSC模型,经斜率/截距算法模型传递后,对于苹果样品,用30个标准样品,RMSEP值达到0.597°Brix,对于桃样品,用40个标准样品,RMSEP值达到0.689°Brix;利用建立的桃SSC模型,经斜率/截距算法模型传递后,对于苹果样品,用35个标准样品,RMSEP值达到0.654°Brix,对于梨样品,用30个标准样品,RMSEP值达到0.439°Brix。研究结果表明:斜率/截距(Slope/Bias)方法可用于苹果、梨、桃等相近种类水果间的模型传递,为近红外光谱仪在相似种类物质间的预测提供了新思路。     

苹果树冠层不同光照区域叶绿素荧光性状计算方法

植物冠层内光照分布决定了植物物理过程与生态环境之间的交互关系,是植物冠层叶绿素荧光动力学研究的重要基础。光谱技术在构建植株冠层组分含量的预测模型中发挥了重要的作用,而针对自由纺锤形苹果树冠层不同光照区域的叶绿素荧光性状研究文献报道较少。因此,以自由纺锤形苹果树为研究对象,将苹果树冠层空间划分为5层,每层划分为边长50 cm的立方体网格,并测定各个网格空间的光照强度,确定其光照分布情况。以此为基础,获取不同光照区域的光谱数据及对应叶绿素荧光性状参数值,通过光谱一阶微分去除系统误差干扰,确定红边区域(660～760 nm)的一阶微分光谱曲线,利用BP神经网络建立红光范围(680～760 nm)内一阶微分光谱最大值与叶绿素荧光性状参数关系模型,创新性地提出了苹果树冠层不同光照区域的叶绿素荧光性状计算方法。并采用决定系数、均方根误差、平均绝对百分比误差等对模型进行有效性评价,试验结果表明：该叶绿素荧光计算方法的计算精度均在80%以上,研究成果可为苹果树的整形修剪,获取充足光照分布提供理论依据。     

基于高光谱的苹果花氮素含量预测模型研究

苹果花氮素含量是反映其质量高低的重要因素,利用高光谱技术对苹果花氮素含量进行定量化反演,可为苹果信息化管理提供理论依据。在室内条件下,利用ASD FieldSpec 3地物光谱仪,测定了120个盛花期苹果花样品的高光谱反射率,并化验了其氮素含量。在分析苹果花原始光谱和一阶导数光谱特征的基础上,与其氮素含量进行相关分析,确定敏感波段,构建特征光谱参数,建立氮素含量预测模型,对模型进行了优选和检验。结果表明,苹果花氮素含量与原始光谱反射率在374～696,1 340～1 890,2 052～2 433 nm波段呈极显著负相关,在736～913 nm呈极显著正相关;与一阶导数光谱反射率在637～675 nm呈极显著负相关,在676～746 nm呈极显著正相关。构建的6个特征光谱参数与苹果花氮素含量均呈极显著相关。通过进一步比较和筛选,确定了基于640 nm和676 nm原始光谱反射率的2个苹果花氮素含量最佳预测模型。经检验,模型决定系数R2分别为0.825 8和0.893 6,平均预测精度达92.9%和94%。研究成果为快速预测苹果花氮素含量及苹果的实时营养诊断提供了理论依据和技术支撑。     

High-performance liquid chromatographic determination of major organic acids in apple juices and ciders

Summary A reversed-phase high-pressure liquid chromatographic method is presented for the simultaneous separation and determination of malic, citric, lactic, succinic and ascorbic acids in apple juices and ciders. After filtration and/or degasification, the organic acids in the sample are separated on a LiChrosorb/C₁₈ column and quantified by using a rapid diode array detector. The method is considered to be a suitable choice for the accurate and precise determination (C.V. 5%) of these compounds.     

Comparison of indices and multivariate models to non-destructively predict the fruit chlorophyll by means of visible spectrometry in apple fruit

Non-destructive, rapid, instrumental tools in fruit production are required for predicting the optimum harvest window and monitoring fruit quality during shelf life. The degree of chlorophyll degradation is a sensitive indicator for fruit maturation and ageing. Adequate indices for chlorophyll prediction by means of non-destructive spectral analysis have been studied in the fields of photosynthesis research and remote sensing developments. However, an evaluation of these indices and multivariate linear regression models does not exist so far for predicting the fruit chlorophyll content.Spectral transmittance recordings in the visible wavelength range were carried out on apple fruit Malus domestica Borkh. ‘Elstar’ (n=99) and ‘Jonagold’ (n=117). The fruit chlorophyll a content of ‘Elstar’ apples was measured wet-chemically and predicted by means of the specific indices: NDVI, Tr₆₉₈/Tr₇₆₀, red-edge, TrII on Tr′(λ), TrII, and RVSI with the correlation coefficients of determination R²=0.84, 0.81, 0.75, 0.81, 0.15, and 0.67, respectively. Partial least-squares (PLS) calibration models were built using calibrated spectra (630-730 nm), first derivative of spectra and second derivative of spectra yielding multivariate correlation coefficients of determination R²=0.81, 0.86, and 0.92, respectively. Similar results were found for ‘Jonagold’ apple fruit. Linear regression of indices and PLS calibration models were empirically tested on the chlorophyll a content of apple fruit measuring the same cultivars grown in a different seasons and growing locations. In the case of ‘Elstar’ apple fruit, correlation coefficients of fruit chlorophyll a content analysed wet-chemically as well as fruit maturation measured as calendar weeks were similar to those in the calibration experiment. Application of linear regression equations of indices and PLS models on spectra of ‘Jonagold’ apple fruit led to less accurate results for those methods, which use wavelengths above 720 nm as indicative range.     

Quantitative determination of (-)-epicatechin in cider apple juices by (1)H NMR

This paper reports a quantitative determination method of (−)-epicatechin in apple juices by measuring of its signal at 7.05 ppm in the ¹H NMR spectrum. It is a direct method that does not need any previous derivatization. 1,3,5-Benzenetricarboxylic acid was added to the juice as internal standard for the determination of the absolute concentration of (−)-epicatechin. Ascorbic acid was also added to avoid enzymatic oxidation of the phenolics and to adjust the pH at 2.74, since the chemical shift of some compounds varies with the pH. Standard addition method accomplished with the juices of two different varieties of apples gave recoveries between 95 and 109%. The precision of the method was tested for repeatability (n=5) and reproducibility (n=13) obtaining a coefficient of variation of 5.8 and 8.6%, respectively. Limit of detection, calculated from “3S_y/x+intercept”, is 24 mg l⁻¹.     

Application of HPLC to characterization and control of individual acids in apple extracts and ciders

Summary Three HPLC methods have been tested in order to compare their separation of apple and cider organic acids. Optimum results for simultaneous determination of malic, citric, quinic, succinic, lactic and shikimic acids have been obtained using an RP-18 column with phosphate buffer as the mobile phase.This method was applied to organic acids monitoring during the ripening of apples and throughout the fermentation process. After filtration and degasification the organic acids in the sample were separated, and quantified by using a diode array detector.Recovery studies show good results for all solutes (88%–106%). The coefficients of variation show excellent precision (5%).     

HPLC法同时测定苹果及浓缩苹果汁中吡虫清等4种农药的残留量

建立了反相高效液相色谱-双波长检测法同时测定苹果及浓缩苹果汁中多菌灵、噻菌灵、吡虫啉、吡虫清4种农药残留量的方法。苹果样品经乙腈提取,加水稀释,而浓缩苹果汁样品直接用体积分数20%乙腈稀释后,利用CH2Cl2液-液萃取净化。分析时用C18色谱柱分离,以乙腈-0.05%冰乙酸系统梯度洗脱,选择246 nm和280 nm双波长检测。该方法4种农药的线性关系良好(r≥0.9999),检出限均为0.002 mg/kg,加标回收率在84.3%~109.1%范围内,相对标准偏差为2.0%~5.4%。本方法能够满足农药残留检测要求。     

Factors that hinder the success of SIM-based mobile NFC service deployments

Near Field Communication (NFC) enables bidirectional wireless proximity communication between mobile handsets. From an end user point of view, mobile NFC services are expected to replace plastic cards (for payment, ticketing, transport, etc.) by bringing improved convenience and functionality. SIM cards have been used to secure the data and applications that implement mobile NFC services. A total of 300 commercial and pilot SIM-based mobile NFC service initiatives have been reported in 2015. However, their deployment is so complex that no commercial solution has succeeded in reaching out the mass market with few exceptions in special institutional settings (e.g. Japan). Although particularly urgent to the telecom industry, existing scientific research provides limited explanations to why these initiatives are not succeeding. We present a framework that identifies twenty-six factors that hinder the success of SIM-based mobile NFC service deployments.