Photostimulated luminescence detection of irradiated herbs, spices, and seasonings: international interlaboratory trial

An interlaboratory trial was conducted to validate photostimulated luminescence (PSL) methods for herbs, spices, and seasonings. Forty products (11 herbs, 17 spices, and 12 seasonings) were purchased from a local commercial source, and randomly selected samples were irradiated with 10 kGy. Four blended products were prepared at Scottish Universities Research and Reactor Centre, mixing varying proportions of irradiated material with the untreated product. Precharacterization against a predefined threshold identified low sensitivity products (black and white peppers) and products with high natural signals (thyme, sage, parsley, and mixed herbs), both of which might be susceptible to misclassification. Precharacterization also revealed whether calibration was likely to resolve overlap between classification categories. Eight sets of screening data and 5 sets of calibrated data were returned by participants. Of the 840 samples sent, 1593 screening measurements and 788 calibrated measurements were received from 662 samples. In screening mode, participants reached definitive conclusions in 87% of cases, 99% of which were correct. Of the remaining 13%, calibration to identify low-sensitivity resolved 60% of cases. Overall, 94% of samples were correctly identified by either screening alone, or screening plus calibration; 6% remained unclassified and therefore required further investigation by thermoluminescence. The results confirm the validity of the PSL method for herbs, spices, seasonings, and blends, and emphasize the need for calibration to identify low-sensitivity samples. This method has now been adopted by the European Committee for Standardization (CEN) and the Codex Alimentarius Commission.     

Volatile compounds and odor preferences of ground beef added with garlic and red wine,and irradiated with charcoal pack

Irradiation is the most efficient non-thermal technology for improving hygienic quality and extending the shelf-life of food products. One of the adverse effects of food irradiation, however, is off-flavor production, which significantly affects the sensory preferences for certain foods. In this study, garlic (5%, w/w) and red wine (1:1, w/w) were added to ground beef to increase the radiation sensitivity of pathogens and improve meat odor/flavor. Samples were irradiated at 0 or 5 kGy in the presence of charcoal pack. SPME-GC–MS analysis was performed to measure the changes in the volatile compounds and sensory characteristics of the samples. The amount of total volatile compounds produced from ground beef was greater when the sample was irradiated. When garlic and red wine were added to the ground beef, the amount of volatile compounds significantly increased, and the amount of volatile compounds increased even further after irradiation. However, when the samples were irradiated with charcoal pack, the amount of volatile compounds decreased significantly. Sensory evaluation indicated that charcoal pack significantly increased the odor preferences for both irradiated and non-irradiated ground beef added with garlic. These results indicated that addition of charcoal pack to ground beef could reduce off-odor problems induced by irradiation, and this effect was consistent even when certain additives such as garlic and red wine were added.     

Identification of radiolytic marker compounds in the irradiated beef extract powder by volatile analysis

In order to develop a new detection method for marker compounds from irradiated powdery foods, two different extraction methods such as solid phase microextraction (SPME) and purge and trap (P&T) methods, were used to detect radiolytic volatile compounds as marker compounds by testing beef extract powder. Beef extract powder was irradiated using a ⁶⁰Co source (γ-irradiation) at 1, 3, 5 and 10 kGy, and then divided into 0 and 30 days of storage (30±1 °C). In 0 day of storage, each concentration of 1,3-bis(1,1-dimethylethyl)benzene as a marker compound detected simultaneously by the extraction methods, increased linearly with irradiation dose (p<0.05) and had the same trend after 30 days of storage. Meanwhile, four other compounds such as tridecane, hexadecane, 2-octene and 2-decanone were excluded from possible marker compounds because these compounds were detected initially but soon disappeared. Another reason is that these compounds were detectable in non-irradiated samples. In this study, therefore, 1,3-bis(1,1-dimethylethyl) benzene was selected as a maker compound in irradiated beef extract powder.     

Synthesis and luminescence properties of ZnS and metal (Mn,Cu)-doped-ZnS ceramic powder

ZnS and metal (Mn, Cu)-doped-ZnS were successfully prepared by wet chemical synthetic route. The understanding of substituted metal ions (Mn, Cu) into ZnS leads to transfer the luminescent centre by small amount of metal dopant (Mn, Cu). Fourier transform infrared and X-ray diffraction were used to determine chemical bonding and crystal structure, respectively. It showed that small amount of metal (Mn, Cu) can be completely substituted into ZnS lattice. X-ray fluorescence was used to confirm the existence of metal-doped ZnS. Scanning electron microscope revealed that their particles exhibits blocky particle with irregular sharp. Laser confocal microscope and photoluminescence spectroscopy showed that ZnS and metal-doped-ZnS exhibited intense, stable, and tunable emission covering the blue to red end of the visible spectrum. ZnS, Mn-doped-ZnS and Cu-doped-ZnS generated blue, yellow and green color, respectively.     

超细红色荧光粉LaMgAl_(11)O_(19):Eu~(3+)的制备与发光性能

采用凝胶-燃烧法制备了稀土Eu3+掺杂的LaMgAl11O19红色荧光粉的前驱粉末,在低于700℃退火处理时,得到非晶态样品,而高于850℃退火处理后为单一六方相结构LaMgAl11O19:Eu3+样品.SEM结果表明,该法制备的样品为颗粒分布均匀,粒径在200～400nm之间的超细粉末.通过激发光谱和发射光谱研究了Eu3+在LaMgAl11O19基质中的发光性能,结果显示,非晶态和晶态La1-xMgAl11O19:xEu3+样品都可发光,在613nm波长光的监测下所得荧光粉的激发光谱为一宽带和系列锐峰,其最强激发峰出现在蓝光465nm处,次强峰为394nm,表明该荧光粉与广泛使用的紫外和蓝光LED芯片的输出波长相匹配.在465nm波长光的激发下观察到超细LaMgAl11O19粉末中Eu3+的613nm(5D0→7F2)强的特征发射,且随着粉末逐渐成相5D0→7F2跃迁明显增强,说明LaMgAl11O19:Eu3+超细粉末可作为白光LED的红色补偿荧光粉.     

Extraction methods of red blood cell membrane proteins for Multidimensional Protein Identification Technology (MudPIT) analysis

Since red blood cells (RBCs) lack nuclei and organelles, cell membrane is their main load-bearing component and, according to a dynamic interaction with the cytoskeleton compartment, plays a pivotal role in their functioning. Even if erythrocyte membranes are available in large quantities, the low abundance and the hydrophobic nature of cell membrane proteins complicate their purification and detection by conventional 2D gel-based proteomic approaches. So, in order to increase the efficiency of RBC membrane proteome identification, here we took advantage of a simple and reproducible membrane sub-fractionation method coupled to Multidimensional Protein Identification Technology (MudPIT). In addition, the adoption of a stringent RBC filtration strategy from the whole blood, permitted to remove exhaustively contaminants, such as platelets and white blood cells, and to identify a total of 275 proteins in the three RBC membrane fractions collected and analysed. Finally, by means of software for the elaboration of the great quantity of data obtained and programs for statistical analysis and protein classification, it was possible to determine the validity of the entire system workflow and to assign the proper sub-cellular localization and function for the greatest number of the identified proteins.     

Synthesis,structure, and luminescence of rhenium(I) complexes with substituted bipyridines

Two new rhenium(I) complexes chelated by a substituted 2,2′-bipyridine with general formula Re(CO)₃LCl, where L?=?6?-(2″-methoxyphenyl)-2,2′-bipyridine (L₁ ) and 6?-(4″-diphenylaminophenyl)-2,2′-bipyridine (L₂ ), are synthesized and characterized by IR, NMR, and elemental analysis. Structure of 1 was determined by single-crystal X-ray crystallography, revealing that rhenium is six-coordinate octahedral. The electrochemical, photophysical, and thermal properties of the two rhenium(I) complexes were investigated. Electroluminescent devices were fabricated by doping 1 in polymer blend host of poly(vinylcarbazole) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole using simple solution spin-coating technique. The device exhibits a maximum current efficiency of 2.97?cd?A^?1 and peak brightness in excess of 2390?cd?m^?2.     

Quantitative analysis by (p,X) and (p, γ) reactions at low energies

Production of atomic X-rays and nuclear γ-rays by bombardment with 0–3 MeV protons of thick targets is described. In the case of low-Z atomic X-rays, the absorption in the target is very large, while in the case ofK X-rays from high-Z atoms or for γ-rays, this phenomenon is negligible. Both of these reactions can be used for analysis of elements from F to U, and the sensitivities and the accuracies of the determinations are discussed. A table is given showing the γ-ray energies observed in 11 substances and the limits of sensitivity.     

Thermal,tensile and rheological properties of linear low density polyethylene (LLDPE) irradiated by gamma-ray in different atmospheres

The aim of this paper is to investigate structural changes of linear low density polyethylene (LLDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical–chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of ⁶⁰Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of LLDPE, after gamma irradiations were evaluated using thermogravimetric analyzer (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.     

Ionic and excited species in irradiated poly(vinyl chloride) doped with aromatic admixtures: low temperature studies

The influence of temperature (77–290 K) on the fate of dopant radical ions and respective excited states in irradiated poly(vinyl chloride) (PVC) matrix, doped with pyrene, (Py) and tris(2-ethylhexyl) trimellitate (TOTM) is described. At 77 K dopant radical ions start to recombinevia tunneling charge transfer, leading to weak isothermal luminescence (ITL). The wavelength-selected radiothermoluminescence (WS RTL) broad maxima observed for doped PVC in the temperature range 95–110 K have a similar origin, i.e., recombination of dopant radical ionsvia tunneling. Apart from the peaks representing the absorption of dopant radical ions the absorption maximum at 411 nm found for the PVC−Py system is attributed to Py−Cl adduct generated in Py^•++Cl⁻ reaction. The mechanisms involved in these processes are discussed.     

Crystal structure,luminescence, and thermochromic properties of bis(tetraethylammonium) hexabromotellurate(IV)

The atomic structure of ((C₂H₅)₄N)₂TeBr₆ crystals (a = 17.930(8) Å, b = 11.133(5) Å, c = 15.022(7) Å, β = 109.28(9)°, space group C2/c, Z = 4, ρ_calcd = 2.036 g/cm³) has been studied by X-ray diffraction. The ((C₂H₅)₄N)₂TeBr₆ crystal structure consists of isolated [TeBr₆]^2? anions and ((C₂H₅)₄N)⁺ cations. The electronic and geometric aspects that influence the luminescence and thermochromic properties of the complex have been considered.     

Determination of lasalocid with sensitized terbium(III) luminescence detection

The luminescence of the lasalocid-terbium(III) system in the presence of Triton X-100 and trioctylphosphine oxide has been studied by obtaining kinetic and equilibrium measurements and using the stopped-flow mixing technique. The initial rate and luminescence signal of this system are directly proportional to the lasalocid concentration, which allows one to develop very simple, fast, automatic methods for the determination of this analyte. Kinetic and equilibrium data can be obtained in only 0.1 and 10 s, respectively. The calibration graphs were linear over the range 0.004-5.0 mug ml(-1) (kinetic method) and 0.01-5.0 mug ml(-1) (equilibrium method) and the detection limits achieved were 1 and 3 ng ml(-1), respectively, equivalent to 2 and 6 ng g(-1) lasalocid in a chicken liver sample, which are similar to those afforded by the chromatographic methods described for this determination. The relative standard deviation of both methods was close to 2%. The analytical recoveries obtained by applying the kinetic and equilibrium methods to drinking water, poultry feed and chicken liver samples ranged from 95.6 to 102.1% and from 95.9 to 104.9%, respectively.     

Preparation,characterization, and luminescence of (SBA-15) immobilized pepsin

SBA-15 mesoporous silica was synthesized by hydrothermal method and its surface was methylated by treatment with methyltrimethoxysilane. Pepsin was immobilized on the obtained materials giving host-guest composite materials (SBA-15)-pepsin and (methylated SBA-15)-pepsin. The optimum conditions for preparation of these materials were established. Methylated SBA-15 (M-SBA-15) has improved immobilization efficiency of enzyme compared to initial SBA-15 silica. It was shown that with the gradual increase of NaCl solution ionic strength the immobilized amount of enzyme was reduced. Powder X-ray diffraction and Fourier transform infrared spectroscopy showed that the host frameworks in the prepared host-guest composite materials are intact and the ordered structure was retained. Scanning electron microscopic studies revealed fibrous morphologic characteristics of the SBA-15 and the immobilized pepsin composite materials. The average particle diameter of (SBA-15)-pepsin composite was 338 ± 10 and 343 ± 10 nm for (M-SBA-15)-pepsin. The low temperature N₂ adsorption-desorption study at 77 K showed that the pore sizes and specific surface areas of the host-guest composite materials were smaller than those before the introduction of the enzyme, suggesting that the immobilized enzyme occupied a definite position in the host material pore channels. The UV-vis solid diffuse reflectance and luminescence studies showed that the enzyme was successfully immobilized on to the host material and that after the immobilization of enzyme on SBA-15 the conformation of pepsin macromolecule has not been changed.     

Facile synthesis, structure, and luminescence properties of Pt(diimine)bis(arylacetylide) chromophore-donor dyads

The luminescent complex Pt(dpphen)bis(arylacetylide) complex (1) (dpphen = 4,7-diphenylphenanthroline and arylacetylide = 4-ethynylbenzaldehyde) has been synthesized and characterized structurally and spectroscopically. Complex 1 has been employed in the synthesis of donor-chromophore (D-C) dyads through Schiff base condensations of different anilines to give imine-linked dyads 2-4 and through imine reduction with borohydride, to give the corresponding amine-linked dyads 2a-4a. Crystal structure determinations of 1-4 and 4a establish a distorted square-planar geometry around the Pt(II) ion in each system with cis arylacetylide ligands and a diimine-constrained N-Pt-N bond angle of ca. 79.5 degrees. Complex 1 is strongly emissive having a relative quantum yield (phi) of 36% and an excited-state lifetime of 3.1 micros. In accord with the notion of photoinduced electron transfer from the aniline-based donor to the photoexcited chromophore, the emission of dyads 2-4 and 2a-4a is effectively quenched in all solvents tested. The intense absorption at 400 nm (30000-70000 L/mol.cm) for 2 and 2a has been assigned as an intraligand pi-pi* transition, whereas the lowest-energy transitions for all other dyads correspond to Pt-to-pi(diimine) MLCT transitions. Although the dyads can be synthesized in a facile manner, photolysis experiments reveal that both the imine and amine linkages are photochemically unstable, resulting in hydrolysis and regeneration of the aldehyde-containing chromophore 1.     

Magnetic field effects on the luminescence of Cs[Au(CN)2] at low temperatures

The effects of a magnetic field on the luminescence lifetime and spectrum of microcrystalline Cs[Au(CN)₂] from 2 to 20 K are reported. The lifetime of the 458 nm phosphorescence band at 4 K decreased. In addition, the field produces a blue shift of the band, reaching 75 cm⁻¹ at H = 1.0 T. These effects are in accord with our previously proposed model and are used to determine further details of that model. A new assignment of the 416 nm emission band as fluorescence is made based on its observed lifetime (τ < 10 ns), energy, and intensity variation with temperature.     

Sensitized near-IR luminescence of Ln(III) complexes with benzothiazole derivatives

Lanthanide complexes with benzothiazole derivatives (Btz-R, R = OCH(3) and OH) and terpyridine (tpy) ligands were synthesized, and their photophysical properties were precisely investigated. The free Btz-OCH(3) ligand in toluene, excited with UV light, produced the normal emission bands around 410 nm, whereas Btz-OH produced a strong excited-state intramolecular proton transfer (ESIPT) band at 510 nm. The Ln(III) complexes (Ln = Nd, Er, and Yb) exhibited sensitized near-IR luminescence when the Btz-R ligands were excited. The sensitized luminescence quantum yields (Phi(Ln)) of the lanthanide complexes were markedly enhanced by ESIPT: for [Nd(Btz-R)(tpy)] in toluene solution, Phi(Ln) = 0.04% for Btz-OCH(3) and 0.39% for Btz-OH. The sensitized luminescence of the Er(III) complexes (Phi(Ln) = 0.002% for Btz-OCH(3) and 0.009% for Btz-OH) was less efficient than that of the Nd(III) complexes. This difference is due to the smaller energy gap between the emitting and ground levels of the Er(III) ion. The rate constants for the energy transfer from Btz-R to Ln(III) were about approximately 10(9) s(-1), as evaluated by the F?rster resonance energy transfer mechanism.     

Crystal structure and luminescence of antimony(III) bromide with aniline

The atomic structure of antimony(III) bromide crystals with anilinium was determined by X-ray diffraction analysis of (C₆H₅NH₃)₂SbBr₅ (a = 19.704(3) Å, b = 7.914(1) Å, c = 25.556(4) Å; space group Pbca, Z = 8, ρ_calc = 2.365 g/cm³). The crystal structure consists of infinite chains of [SbBr₅]^2? complex anions formed by sharing six vertices and the anilinium (C₆H₅NH₃)⁺ cations, through which the chains are linked in layers by N-H...Br hydrogen bonds. The geometrical aspects that determine the luminescent spectral properties of the complex are discussed.     

Solid-state luminescence of Au(I) complexes with external stimuli-responsive properties

In the last decade, the field of stimuli-responsive luminescent materials have been intensely emerged because of the high potential application to functional sensors or photoelectronic devices. In particular, luminescent molecular crystals constructed from Au(I) complexes have produced a wide range of examples of luminescent alterations when some external stimulations, such as heat, mechanical stress, vapor (or solvents), were applied to the solid samples. In this review, we describe the recent progress through a summary of the reported Au(I) complexes based on their utilized stimuli-responsive mechanisms, which are categorized in crystal phase transitions (“crystal-to-amorphous”, “crystal-to-crystal” and “single-crystal-to-single-crystal” transitions) and molecular rotation in crystalline media, respectively.     

IR luminescence of neodymium(III) and ytterbium(III) complexes with acylpyrazolones in solutions

Acylpyrazolones (L1–L5) have been synthesized and the conditions of their complexation with neodymium(III) and ytterbium(III) ions in aqueous solutions have been elucidated. The component ratio in the synthesized complexes is Nd(Yb): L = 1: 1. The conditions of excitation and luminescence of the ligands and complexes have been studied. The formation of mixed-ligand complexes upon the introduction of trioctyl- or triphenylphosphine oxide leads to a considerable rise of neodymium and ytterbium. In the presence of 1,10-phenanthroline and bathophenanthroline, competing complexation leads to a 20–70% decrease in luminescence intensity. The introduction of water-miscible organic solvents (30 vol %) decreases the Nd(III) and Yb(III) luminescence intensity by a factor of 9–20.