Simultaneous determination of sugars and organic acids in aged vinegars and chemometric data analysis

Aceto Balsamico Tradizionale of Modena (ABTM) is a typical product (PDO denomination) of the province of Modena produced by cooked grape must which undergoes a long ageing period (at least 12 years) in series of wooden casks (batterie). The study of the transformations of this product during ageing is extremely relevant in order to control the authenticity of ABTM towards succedaneous products and mislabelling of age.

This paper presents the results of the investigation of sugars and fixed organic acids in ABTM samples of different ages, coming from different batterie. The analytes were simultaneously determined by a gas chromatographic method optimised for this peculiar matrix.

The method shows good separation and resolution of the investigated chemical species and allows their determination in the concentration ranges reported in brackets: malic (7.6–15.5 g kg⁻¹), tartaric (4.0–9.7 g kg⁻¹), citric (0.6–1.5 g kg⁻¹) and succinic (0.36–0.62 g kg⁻¹) acid and glucose (153–294 g kg⁻¹), fructose (131–279 g kg⁻¹), xylose (011–0.39 g kg⁻¹), ribose (0.078–0.429 g kg⁻¹), rhamnose (0.061–0.195 g kg⁻¹), galactose (0.136–0.388 g kg⁻¹), mannose (0.41–1.46 g kg⁻¹), arabinose (0.33–1.00 g kg⁻¹) and sucrose (0.46–6.84 g kg⁻¹), with mean associated errors ranging from 5 to 19% depending on the analytes.

Moreover, the recovery values are always satisfactory, being close to one for most of the analytes.

Furthermore, in order to assess the degree of variability of the different analytes content with vinegar ageing and the similarity/dissimilarity among series of casks a three-way data analysis method (Tucker3) is proposed. The chemometric technique applied on the data set shows differences between the samples on the bases of their different ageing period, and between the batterie, which traditionally have an own peculiar production procedure.     

Long-range ordering of composites for organic electronics: TIPS-pentacene single crystals with incorporated nano-fibers

Fluorescent nanofibers are incorporated into high-mobility single-crystals without substantially disrupting crystalline lattice, demonstrating a strategy to multifunctionalize semiconducting single-crystals.     

A piezoelectric quartz crystal sensor array self assembled calixarene bilayers for detection of volatile organic amine in gas

P-tert-butylcalix[n]arenes (n=4, 6, 8, abbreviated as CA[4], CA[6], CA[8], respectively) were immobilized on the Au surface of the piezoelectric quartz crystal by the reaction between CA[n] and the acid chloride terminated mercaptoacetic acid (MAA) self assembled monolayers to form MAA/CA[n] bilayers. The sensing films were not only immobilized easily and reproducibly, but also used to improve the reversibility of the sensor signal. The response characteristics show the response of CA to organic amine attributes to specific interaction between CA[n] (host) and organic amines (guest). The frequency shifts of n-butylamine and iso-butylamine are much larger than tert-butylamine and diethylamine because of shape-selection and hydrogen bonding. Compared to CA[6] and CA[4], CA[8] has highest sensitivity to organic amine due to having more flexibility to accommodate guest molecules. A sensor array with three-layer back-propagation neural network was applied to detect the binary mixture of n-butylamine in the range of 7.14–142 μl l⁻¹ and iso-butylamine in the range of 7.14–57 μl l⁻¹. The optimum values of learning rate (0.15) and momentum term (0.8) were determined by experiment. The best epoch of training was 1098. The root mean square error of prediction was 1.69 (μl l⁻¹) for n-butylamine, and 1.42 (μl l⁻¹) for iso-butylamine.     

Photosensitized degradation of organic pollutants in water: processes and analytical applications

Photosensitized degradation has been used to remove a broad range of organic pollutants, generally with mineralization to CO₂ and other inorganic products such as Cl⁻ and . TiO₂ and Fe³⁺ are the photosensitizers mainly used to accelerate the degradation of persistent organic chemicals. Various analytical techniques were used to identify the degradation products and to monitor the degradation kinetics. Chromatographic techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC) and ion-exchange were used. Other analytical techniques, such as total organic carbon analysis, UV–visible spectrophotometry, spectrofluorimetry, and potentiometry, were also used. When the photodegradation is carried out in water, extraction methods such liquid–liquid extraction or solid-phase extraction need to be used, followed by GC or HPLC analysis. We review the analytical methods used for the identification of the products formed in photodegradation studies. Kinetic studies of the degradation are also reported.     

Dynamic control and indirect absorption detection for high-speed capillary electrophoretic separation of organic acids

Dynamic control and indirect absorption detection have been combined for the separation of eight small aliphatic organic acids in less than 4 min. Electroosmotic flow (EOF) coefficients in 5 mM 8-hydroxyquinoline-5-sulfonic acid (8-HQSA) (pH 3.00) and 3 mM 1,2,4,5-benzenetetracarboxylic acid (BTA) solutions are 4.35 and 1.65·10⁻⁴ cm²/V s, respectively. In the BTA system, relatively large amounts of sodium ions adsorbed into the capillary wall are the most probable reason for the small EOF, in turn causing problems for the separation of all acids. In contrast to BTA, 8-HQSA could be used for the separation of all eight organic acids. Limits of detection of analytes are at the level of several tens of μM at pH 3.00 in the 8-HQSA system. This new technique provides several features such as high speed, reasonable resolution and sensitivity, and ease of operation.     

Effective design of A-D-A small molecules for high performance organic solar cells via F atom substitution and thiophene bridge

Novel A-D-A-type small molecule donors employ thiophene bridge and F-substitution to improve the power conversion efficiency in organic solar cell.     

The role of organic acids in mineral weathering

Organic acids and their anions (for brevity we shall use the term “acids” to include both) may affect mineral weathering rates by at least three mechanisms: by changing the dissolution rate far from equilibrium through decreasing solution pH or forming complexes with cations at the mineral surface; by affecting the saturation state of the solution with respect to the mineral; and by affecting the speciation in solution of ions such as Al³⁺ that themselves affect mineral dissolution rate. In this paper we review the effects of organic acids on the dissolution rates of silicate minerals, particularly feldspars, under conditions approximating the natural weathering environment −25°C, pH 4–7 and with concentrations of organic acids comparable to those measured in soil solutions.

Feldspar dissolution rates far from equilibrium increase with decreasing pH below pH 4–5. They appear to be independent of pH between pH 4–5 and about 8, and above pH 8 feldspar dissolution rates increase with increasing pH.

Small chelating ligands such as oxalate appear to accelerate feldspar dissolution through complexation of Al at the surface of the mineral. Feldspar dissolution rates in the presence of 1 mM oxalic acid show effects ranging from no enhancement to enhancements of a factor of 15, depending upon the data set, pH, and aluminum content of the mineral: there is a great deal of scatter in the available data. In general, concentrations of oxalate of the order of 1 mM are necessary to cause a significant effect. Humic acids do not appear to increase feldspar dissolution rates significantly.

Dissolution rates must decrease as the solution approaches saturation with respect to the primary phase (the chemical affinity effect). Organic acids will influence chemical affinity by complexing Al (and possibly other elements) in solution and hence decreasing the chemical activity of Al³⁺. There are essentially no data on the effect of chemical affinity on feldspar dissolution rate at 25°C and mildly acid pH, so it is hard to evaluate the importance of organic acids in accelerating silicate dissolution through the chemical affinity effect. The effect of complexation of dissolved Al does not appear to be an important determinant of silicate dissolution rates in nature.

Observed rates of silicate weathering in the field are typically much slower than predicted from laboratory experiments far from equilibrium, suggesting control by transport of solutes between “micropores” and “macropores” (“micropores” include fractures and crystal defects within grains). If such transport is rate-controlling, analysis of the effect of organic acids on weathering rates in nature in terms of dissolution rates far from equilibrium may be misleading.     

The electrochemical advanced oxidation processes coupling of oxidants for organic pollutants degradation: A mini-review

In this mini-review, the homogeneous and heterogeneous EAOPs-oxidant processes were summarized. The reaction mechanisms of different EAOPs combined with different oxidants are elucidated in detail, as well as the synergistic effect for improving the treatment efficiency.     

Hexyl substitution of pentathienoacene toward a significant improvement in charge transport

The introduction of hexyl chains endows the semiconductor with two or three orders of magnitudes enhancement in carrier mobility or current on/off ratio respectively.     

Development of soft plasma ionization (SPI) source for analysis of organic compounds

We present a newly designed soft plasma ionization (SPI) source developed for mass spectrometric study of organic compounds in this study. The SPI cell having a relatively small size consists of a hollow anode and a hollow mesh cathode. The voltage–current characteristic depending on the pressure was investigated, indicating that it has similar characteristics to conventional hollow cathode glow discharges. To investigate the emission characteristics of the SPI source, some molecular band emission spectra (N₂, N₂⁺ and OH⁺) were measured by using argon and helium discharge gases. The SPI source was installed to a commercially used quadrupole mass analyzer for analyzing organic compounds. To demonstrate the SPI source, the mass spectra of some organic compounds (methylene chloride, toluene, benzene, cyclohexane and chloroform) were measured. The organic compounds were ionized with good stability in the plasma, and the fragmentation depended on the applied current. When helium and argon gases were used as the discharge gas, the helium plasma was more suitable for SPI-MS rather than argon because the argon plasma not only suffers from spectral interference but also has lower sensitivity.     

Development and optimization of organic acid analysis in tobacco with ion chromatography and suppressed conductivity detection

With the aid of a central composite face-centered design, an ion chromatographic method was developed and optimized for analyzing organic acids in tobacco. A Dionex-100 ion chromatograph with an ion suppressor and a conductivity detector, and a Bio-Rad Aminex HPX-87H column were employed. Only 13 analyses were required to optimize two factors: column temperature and eluent strength. Two sets of optimal conditions for separating nine acids were found: 1.8 mM HFBA eluent and 42 °C column temperature, and 0.8 mM HFBA eluent and 50 °C column temperature. The flow-rate was 0.6 ml min⁻¹ and the analysis time was 18 min or less. A sample preparation procedure included extraction of 2 g ground tobacco with 100 ml of 5 mM sulfuric acid solution for 3 h, filtration of the extract, and dilution of the filtrate 10-fold with deionized water.     

有机配体表面改性NiCo2O4纳米线用于水全分解

由于水分解在绿色能源领域的重要作用,能够在碱性介质中进行析氢(HER)和析氧(OER)反应的双功能电催化剂具有重要的应用价值。本文报道一种具有丰富缺陷的表面改性NiCo₂O₄纳米线(NWs),在碱性介质中作为一种高效的整体水裂解电催化剂。X射线光电子能谱(XPS)分析表明,Co²⁺/Co³⁺比值的增加是表面修饰NiCo₂O₄纳米线具有优异双功能电催化性能的重要原因。结果表明,在1.0 mol·L^-1 KOH溶液中,通过有机配体主导的表面改性,优化后的NiCo₂O₄纳米线在电流密度达到10 mA·cm^-2时的HER过电位仅为83 mV,OER过电位仅为280 mV。更重要的是,有机配体表面改性后的NiCo₂O₄纳米线表现出了出色的水分解性能,在2.1 V电压下达到了100 mA·cm^-2的电流密度。目前的工作凸显了提高NiCo₂O₄ NWs尖晶石结构中Co²⁺含量对促进整体水裂解的重要性。     

Improving the Performance of TIPS-pentacene Thin FilmTransistors via Interface Modification

Understanding the structure-performance relationship is crucial for optimizing the performance of organic thin film transistors. Here, two interface modification methods were applied to modulate the thin film morphology of the organic semiconductor, 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-pentacene). The resulting different film morphologies and packing structures led to distinct charge transport abilities. A substantial 40-fold increase in charge carrier mobility was observed on the octadecyltrichlorosilane(OTS)-modified sample compared to that of the transistor on the bare substrate. A better charge mobility greater than 1 cm²·V^-1·s^-1 is realized on the p-sexiphenyl(p-6P)- modified transistors due to the large grain size, good continuity and, importantly, the intimate π-π packing in each domain.     

Interactions of thorium isotopes with colloidal organic matter in oceanic environments

The phase speciation of thorium and consequences for the residence times of colloids have been examined in seawater of the Middle Atlantic Bight (MAB) and the Gulf of Mexico. Two fractions of colloidal organic matter (COM), 0.2 μm > COM₁ > 1 kD and 0.2 μm > COM₁₀ > 10 kD, were sampled using cross-flow ultrafiltration techniques and measured for their ²³⁴Th activity and organic carbon concentration. The ratios of mass concentrations of COM₁ to those of suspended particulate matter were as high as 10 in the MAB and 6–34 in the Gulf of Mexico. Higher concentrations of colloids may be of great importance in the biogeochemical cycling of many particle-reactive nuclides or trace elements owing to their high specific surface area and complexation capacity. A significant fraction of ²³⁴Th in the traditionally defined “dissolved” pool was found to be associated with colloids. On average, about 10% of “dissolved” ²³⁴Th was in the colloidal fraction of sizes between 10 kDa and 0.2 μm, and 50% was in the 1 kDa-0.2 μm fraction. Values of the partition coefficients [K_c: (0.5−4) × 10⁶ ml g⁻¹ for K_c1 and (0.5−7) × 10⁶ ml g⁻¹ for K_c10] of ²³⁴Th between truly dissolved (<1 kDa) and colloidal fractions approximated those for Th-particle interactions [K_p: (0.3−10) × 10⁶ ml g⁻¹], indicating that colloid and suspended particle surface sites are similar. The distribution of ²³⁴Th between dissolved, colloidal, and particulate phases was broadly similar to that of organic carbon in these oceanic environments. Thus, thorium isotopes might be used as tracers of marine organic carbon cycling. Residence times of colloids derived from ²³⁴Th:²³⁸U disequilibria were consistently short, ranging from 1 to 14 days for COM₁₀ and from 5 to 65 days for COM₁, suggesting that marine colloids are highly reactive in marine biogeochemical processes. The discrepancy between apparent turnover times of colloids (1 kDa) derived from Th scavenging and ¹⁴C measurements suggest that ²³⁴Th and ¹⁴C may trace different geochemical pathways of colloids in the ocean.     

聚(茚并芴-三苯胺)的合成及性能

设计并合成了一类新的可用于有机场效应晶体管(OFET)的聚合物半导体材料聚(茚并芴-三苯胺)(pIFTPA1~4), 通过核磁共振谱和凝胶渗透色谱等对聚合物进行了表征, 同时对其场效应薄膜晶体管性能进行了测试. 结果表明, 这些聚合物形成了无定形半导体膜, 在空气中稳定, 其载流子迁移率远高于聚三苯胺(pTPA)类材料, 其中pIFTPA1载流子迁移率高达4×10^-2 cm²/(V·s), 开关比为10⁶.     

Femtosecond dynamics of electron transfer in a neutral organic mixed-valence compound

In this article we report a femtosecond time-resolved transient absorption study of a neutral organic mixed-valence (MV) compound with the aim to gain insight into its charge-transfer dynamics upon optical excitation. The back-electron transfer was investigated in five different solvents, toluene, dibutyl ether, methyl-tert-butyl ether (MTBE), benzonitrile and n-hexane. In the pump step, the molecule was excited at 760 nm and 850 nm into the intervalence charge-transfer band. The resulting transients can be described by two time constant. We assign one time constant to the rearrangement of solvent molecules in the charge-transfer state and the second time constant to back-electron transfer to the electronic ground state. Back-electron transfer rates range from 1.5 × 10¹² s⁻¹ in benzonitrile through 8.3 × 10¹¹ s⁻¹ in MTBE, around 1.6 × 10¹¹ s⁻¹ in dibutylether and toluene and to 3.8 × 10⁹ s⁻¹ in n-hexane.     

Electroabsorption study of metal-to-ligand charge transfer in an organic complex of iridium (III)

The dipole moment and polarizability changes have been determined from electroabsorption (EA) spectroscopy of solid films of fac tris(2-(phenyl)pyridinato,N,C^2′)iridium (III) [Ir(ppy)₃]. The maximum changes in the dipole moment |Δμ|_S=(5.0±0.5) D/f (f is the local field correction factor: 1.3–1.7) accompany ground state to the lowest singlet, and |Δμ|_T=(1.7±0.5) D/f ground state to the lowest triplet metal-to-ligand charge transfer (MLCT) excited states formation, while the average polarizability change ų/f² follows from the fitting procedure throughout the visible absorption spectrum range. The experimental values of |Δμ| as well as energy positions of the MLCT states correlate with the literature results of time-dependent density functional theory.     

CoFe2O4/CuO活化过氧乙酸高效降解磺胺甲恶唑(英文)

利用化学沉淀法和溶胶凝胶法,通过两步法成功制备出含有尖晶石钴铁氧体和氧化铜的复合催化剂CoFe₂O₄/CuO,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对制备出的CoFe₂O₄/CuO进行表征,探究不同高级氧化体系对磺胺甲恶唑(SMX)去除能力,考察过氧乙酸(PAA)浓度、催化剂投加量、水体中常见干扰物质(Cl^-,HCO-3,SO₄^2-,HA)和不同自由基捕获剂对SMX去除的影响。分析结果表明CoFe₂O₄/CuO同时具有CoFe₂O₄与CuO的特征,对比单独CoFe₂O₄与CuO,CoFe₂O₄/CuO对PAA展现出极高的活化性能,在最佳反应条件下(催化剂投加量=20mg·L^-1,c(PAA)=200μ...     

C_(60)与MoO_3混合材料做空穴注入层的单层有机电致发光器件

我们制备研究了基于结构为氧化铟锡(ITO)/C_(60)(1.2nm):MoO_3(0.4nm)/1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯(TPBi):三(2-苯基吡啶)铱[Ir(ppy)_3](33%,90 nm)/LiF (0.7 nm)/Al (120 nm)的高效绿色磷光单层有机发光二极管(OLED)。分别将C_(60),MoO_3与C_(60):MoO_3混合物作为空穴注入层(HIL)作为对比。TPBi在发光层中起着主体以及电子传输材料的双重作用。在使用电子传输型主体的单层OLED中,空穴注入层性质对于调节电子/空穴注入以获得电荷载流子传输平衡起重要作用。因此,适当调节空穴注入层是实现高效单层OLED的关键因素。由于MoO_3较大的电子亲和能(6.37 eV)会诱导电子从C_(60)的最高占据分子轨道(HOMO)能级转移至MoO_3,从而形成C_(60)阳离子,并使得Mo元素的价态从+6降至+5,C_(60):MoO_3混合就可以较好的调节空穴注入性质。最终实现最大电流效率为35.88 cd·A~(-1)的单层有机发光器件。