Colorless Samples Research Articles

Application of kinetic bioluminescence inhibition assay using live cultures of Aliivibrio fischeri for determination of zinc toxicity

Variation in zinc toxicity with variation in environmental conditions was studied using the kinetic bioluminescence inhibition assay conducted with live cultures of Aliivibrio fischeri. A good correlation was observed between the static assay and flash assay for colorless non-turbid samples. Color and turbidity had negligible impact on the flash assay results while the static assay caused artifacts. Naturally occurring water samples showed wide variation in the toxicity profiles. Change in zinc toxicity was determined in response to variation in hardness, alkalinity and other coexisting cations/anions in model lake water and in the presence of a solid matrix. The presence of other anions and cations in model lake water reduced and enhanced zinc toxicity, respectively, due to changes in zinc speciation, and bioluminescence inhibition was well correlated with free zinc ion concentration. Increase in alkalinity and sulfate in model lake water lowered zinc toxicity, whereas increase in ammonium ions enhanced the toxicity. Variation in toxicity with hardness was dependent on the Ca: Mg hardness ratio in the samples. The presence of solid matrix decreased toxicity of the aqueous extracts, and toxicity of the matrix was found to increase with decreasing grain size. Speciation pattern of zinc in the respective fractions, however, revealed no direct relationship between zinc associated with fraction that are considered bioavailable to higher organism and the observed toxicity. This assay may be recommended for toxicity analysis of environmental samples since most of the results obtained correlate well with observations reported in toxicity studies with higher organisms.

Coloration of molybdenum oxide thin films synthesized by spray pyrolysis technique

Photochromiccoatings of molybdenum oxide films were deposited on glass substrates by spray pyrolysis technique. The samples were prepared at two substrate temperatures of 250°C and 400°C using spray time varying between 1 and 5 min while the other spray operating parameters are fixed at their optimum values. The crystalline nature and crystallite size of the films were investigated by grazing angle X-ray diffraction. The surface topography was characterized by atomic force microscopy roughness data and particle size histograms. The X-ray diffraction patterns prove that the films deposited at substrate temperature of 250 °C and different spray time are amorphous while the films deposited at 400°C and different spray time are crystalline with only α-phase. The particle size distribution for the prepared samples are found to be in the range from 70 to 100nm. The particle size distribution tends to be narrow as the spray time increases which indicates the improvement in homogeneity of the samples. The optical absorption spectra of selected colorless samples before and after UV light irradiation was recorded. Two distinct absorption bands were observed: a sharp one related to the energy gap and a broader one at lower energy of 1.03eV to which the blue color of the sample after UV irradiation is related. This latter band is fitted with three sub-bands E1, E2 and E4 using a Lorentzian model. The intensity and position of these sub-bands depended on UV light exposure time. The sub-bands E1 and E4 are related to the bulk and surface paramagnetic color centers while the E2 band is related to pairing diamagnetic color centers.

Ionic Liquid Electrolytes for Safer Lithium Batteries: I. Investigation Around Optimal Formulation

Ionic liquids (ILs) are more and more investigated as substitutes of volatile and flammable organic electrolyte solvents in rechargeable lithium-ion battery systems [1] to enhance safety of the electrochemical device. So far, single ILs do not generally match or fully satisfy the requirements and/or operative conditions of practical devices, even if the ionic liquid properties could be finely tuned by suitably modifying their architecture [1]. A promising approach is represented by properly combining different ionic liquids, leading to beneficial synergic effects on the physicochemical properties of the resulting IL mixture [1]. In the present work, we have developed ternary mixtures by incorporating different fractions of the LiTFSI salt into the proper PYR13TFSI-PYR13FSI blend. Pyrrolidinium-based ILs were successfully proposed for lithium batteries [1]; the TFSI anion has proved to be stable toward oxidation and thermally robust [1] whereas FSI exhibits high conductivity even at low temperature coupled with protective film-forming capability onto electrodes [1]. Results and Discussions An eco-friendly procedure route [2] allowed to synthesize high purity, anhydrous, clear, colorless and odorless ionic liquid samples with yields ranging from 85 to 90 mol.% and water content below 2 ppm. Proper PYR13TFSI-PYR13FSI formulations have shown ion conduction approaching 10-3 S cm-1 at -20 °C whereas the pure IL materials, still in solid state, exhibit conductivity values four orders of magnitude lower. This behavior is likely due to different hindrance of the anions, resulting in worse ion packing. On the basis of the obtained results, the TFSI:FSI mole ratio was selected equal to 2:3. The LiTFSI-PYR13TFSI-PYR13FSI mixtures (Figure 1) have exhibited high conductivity (about 10-3 S cm-1), even at low temperatures (-20 °C), in good agreement with the thermal and rheological properties. Cyclic voltammetries (Figure 2) have indicated electrochemical stability up to 5 V in conjunction with the possibility to reversibility intercalate Li+ ions into carbonaceous anodes, this also suggesting good mobility of lithium at the interface with electrodes. Acknowledgements The authors wish to thank the financial support of the European Commission for the GREENLION project within the 7th Framework Program (Grant agreement n°: 28526).

Characterisation of Roman and Byzantine glasses from the surroundings of Thugga (Tunisia): Raw materials and colours

Roman and Byzantine glass shards collected during excavation campaigns around the ancient city of Thugga in northern Tunisia have been characterised by means of various analytical techniques. Portable X-ray Fluorescence (pXRF) was used to determine the glass matrix elemental composition and to identify the elements responsible for the colour. Fibre optic reflectance spectroscopy (FORS) was employed to investigate the chemical nature, the oxidation state and the coordination of the chromophores. X-ray photoelectron spectroscopy (XPS) was here exploited for characterising the outermost layers of the glasses. Elemental analyses by pXRF pointed out that Si, Fe, Al, Ca, K, Rb, Sr, Na and Mg are the main elements present in the glasses. The chromophores responsible for the different shades are Fe for the green shades, Cu and Co for the blue ones, Mn, also used as discolouring agent, for the colourless samples. In relation to the raw materials used for glass production, the comparison with control groups of samples from Northern Tunisia suggests a common provenance of sands.

Phytochemical profiling in single plant cell by high performance liquid chromatography-mass spectrometry.

Phytochemicals are essential secondary plant metabolites which play important roles in the areas of plant biochemistry, pharmacy and medical science because of their significant bioactivities. Conventional analysis of phytochemicals in plants needs a complex combination of different extraction and separation steps. Here a simple and universal method for profiling phytochemicals in a single plant cell was demonstrated based on high performance liquid chromatography-mass spectrometry. Single purple and colorless cell samples (about 15 μm in size) found in the outer layer of a young stem of Forsythia suspensa, just inside the cuticles were collected and transferred by glass micropipettes from cell monolayers. At least 30 peaks were separated and detected, and 24 of these peaks were identified. Apart from several common plant metabolites in high abundance, like polysaccharides and amino acids, 9 phytochemicals that have special bioactivities in this plant and in medical treatment were successfully detected. Phytochemical differences between these two kinds of cells were also distinguished which was applied to investigate the heterogeneity of cells from different parts of plants and the dependency of important plant bioprocesses on phytochemical changes.

Identification of Colored Dyes that are Resistant to Fading on Exposure to Ethylene Oxide; Use with Indicating FTA™ Sample Collection Cards

Regulatory Standards and Forensic Communities are expressing an expectation for HID products to be certified as “DNA-free.” Recently, “DNA-free” status was described for HID-related products using ethylene oxide (EtO); this gas reduces the presence of amplifiable DNA and causes minimal interference to downstream HID-analytical methods. During sample collection, indicating cards, for example, Indicating FTA™ (GE Healthcare Life Sciences, UK), are used to collect and store buccal cell DNA. These cards contain a dye which changes color on application of a colorless sample. Generating “DNA-free” indicating cards using EtO should not impact the dyes' ability to indicate sample location or the efficacy of the card in downstream HID-analytical methods. This study was initiated to identify alternative dyes to those currently used with sample indicating collection cards. The most promising, dyes when applied to cellulose papers exhibited a uniform color distribution and excellent sample indicating properties even when mixed with chemicals associated with FTA™. When dyed cellulose papers were exposed to EtO, ultraviolet radiation, elevated temperature, and humidity, negligible fading or discoloration was observed. The presence of these dyes on cellulose papers did not interfere with direct short tandem repeat (STR) profiling. Allelic concordance, first pass success rate, and mean peak heights were comparable to samples applied to Indicating FTA. Biological samples applied to EtO-treated dyed cellulose papers and stored >1 month produced full STR profiles of sufficient quality to allow submission to DNA databases, confirming negligible interference from EtO treatment. These alternative sample indicating dyes resist EtO-mediated fading while fulfilling the Forensic Community's expectation for “DNA-free” with negligible impact on collection card performance.

Classification of plum spirit drinks by synchronous fluorescence spectroscopy

Synchronous fluorescence spectroscopy was used in combination with principal component analysis (PCA) and linear discriminant analysis (LDA) for the differentiation of plum spirits according to their geographical origin. A total of 14 Czech, 12 Hungarian and 18 Slovak plum spirit samples were used. The samples were divided in two categories: colorless (22 samples) and colored (22 samples). Synchronous fluorescence spectra (SFS) obtained at a wavelength difference of 60nm provided the best results. Considering the PCA–LDA applied to the SFS of all samples, Czech, Hungarian and Slovak colorless samples were properly classified in both the calibration and prediction sets. 100% of correct classification was also obtained for Czech and Hungarian colored samples. However, one group of Slovak colored samples was classified as belonging to the Hungarian group in the calibration set. Thus, the total correct classifications obtained were 94% and 100% for the calibration and prediction steps, respectively. The results were compared with those obtained using near-infrared (NIR) spectroscopy. Applying PCA–LDA to NIR spectra (5500–6000cm−1), the total correct classifications were 91% and 92% for the calibration and prediction steps, respectively, which were slightly lower than those obtained using SFS.

Magnetron Sputtering Deposition of Ag/TiO2 Nanocomposite Thin Films for Repeatable and Multicolor Photochromic Applications on Flexible Substrates

It is reported on a reactive magnetron sputtering‐based deposition method to synthesize, at room temperature, photochromic nanocomposite thin films consisting of Ag nanoparticles sandwiched between nanoporous TiO2 layers. The fabrication process is compatible with large‐scale production and functional flexible substrates. It is shown that when TiO2 is deposited in the metallic mode, the formation of Ag metal nanoparticles induces localized surface plasmon resonances in the visible range and therefore the as‐deposited samples are colored. In contrast, when TiO2 is deposited in the compound mode, the trilayer samples are colorless because silver oxidizes during TiO2 deposition. It is demonstrated that the colorless samples can be colored under ultraviolet (UV) laser exposure at 244 nm due to the reduction of oxidized silver and the formation of metallic Ag nanoparticles. Moreover, irradiation at 647 nm wavelength of colored samples (as‐prepared or after UV exposure) gives rise to changes in the particle morphology that strongly modifies the film absorbance and results in a color transition from blue to orange. The choice of the irradiation wavelength allows controlling the color saturation of the sample up to the complete discoloration by using a visible laser at 488 nm. All these photochromic mechanisms are repeatable during cyclic processes.

In-plane electrical bistability of photochromic diarylethene/Cu composite film

Electrical bistability is an essential property for memory devices. We report here the in-plane electrical bistability of photochromic diarylethene (DAE)/Cu composite film, which is prepared by Cu vapor deposition on the DAE surface with a low glass-transition temperature. The low-current level around 10−8A was switched to a high-current level of ca. 10−4A at a low threshold voltage (Vth) in the first voltage sweep. Once this switching occurred, the high-current level was kept in the second voltage sweep, and electrical bistability was achieved for the in-plane current. Vth was distributed in a wide range of voltages (0.5–10V), and the colored sample obtained by the UV irradiation showed a relatively higher Vth than the colorless sample. The highest ON–OFF ratio in current was ca. 106. The origin of the bistability attributed to the electrical breakdown in the insulated lines that was consisted of DAE in Cu film. The in-plane bistability of the DAE/Cu composite film has good retention time (>60min) and readout-cycle endurance (>106 cycles), indicating that it is suitable for write-once organic semiconductor memory characteristics.

Radiochromic Fuchsine‐Gel and Its Possible Use for Low Dosimetry Applications

ABSTRACTA new dyed–gelatin gel shows promise as a stable dosimeter for low‐dose dosimetry processing. Fuchsine acid cyanide (FAC) dye diffuses in gelatin, forming a colorless sample, which developed a color with the increase in absorbed doses. Upon irradiation, the sample turned pink and the color change was measured at 550 nm using UV‐vis spectroscopy. A formulation suitable for dosimetry was investigated by varying the concentrations of FAC. This dosimeter was also evaluated for stability, dose sensitivity, and irradiation effect dependence. On the other hand, it can be used as a dosimeter in a relatively dose range 1 to 170 Gy. The radiation chemical yield (G value) and pre‐ and postirradiation stability were studied.

A water dispersed Titanium dioxide/poly(carbonate urethane) nanocomposite for protecting cultural heritage: Preparation and properties

Abstract A water dispersed Titanium dioxide/poly(carbonate urethane) nanocomposite was prepared by means of cold mixing of single components via sonication. The work was aimed at achieving a new material with properties suitable for eco-sustainable applications in cultural heritage as protective coating. The nanocomposite water dispersion prepared was subsequently deposited on Petri dish and, after water casting at room temperature, homogeneous, transparent, colourless film samples were obtained. TGA, DSC, DMTA, ATR-FTIR, FESEM and WAXS techniques were then applied in order to investigate the thermal and visco-elastic behaviours along with morphology and structure of the nanocomposite. Moreover, through methylorange decomposition, an azoic dye representative of environmental pollution, a photocatalytic test was set up on nanocomposite film samples assessing that the 1% (wt/wt) content of Titanium dioxide nanoparticles was able to confer self-cleaning ability. Interrelationships among structure, properties and uses in conservation of this kind of nanomaterial were appraised.

Spectroscopic properties of halite from Kłodawa salt mine, central Poland

The dynamics of colour centre transformation was investigated in blue halite single crystals from Klodawa Salt Mine, Central Poland, using UV–vis spectroscopy. The following colour centres were considered: F, R1, R2, as well as plasmons and M centres. The R2 centres predominated in navy blue (A) and pale blue (B) halites. Other relatively large populations were plasmons found in all examined samples. In purple (C) halite samples the plasmon population is the highest one among others and R1 centres appeared to be equally significant, whereas M centres were almost absent. For A and C samples unidentified bands were observed at 26,500 to 26,200 cm−1, respectively. The bleaching process of the blue halites was investigated using temperature dependent UV–vis and micro-Raman spectroscopies. In micro-Raman 300–100 cm−1 region three very intense sharp bands were attributed to the colour centres and colloidal Na precipitation in A and B halites. The one broad band in the range 3,500 to 500 cm−1, which was characteristic even for the colourless sample D but absent in the spectra of colourless NaCl obtained after recrystallization of sample A, requires further study.

Refocusing based on amplitude analysis in color digital holographic microscopy

A refocusing criterion adapted to red-green-blue (RGB) digital holographic microscopy is established. It is applicable for both amplitude and phase objects. This color criterion is based on a monochromatic criterion, using the integrated modulus amplitude. Simulated RGB holograms show the value of having color information, even for colorless samples; in addition, the position of the focus plane along the optical axis is determined more accurately. Simulations take into account both the numerical apertures of lenses and noise during the holographic process. We also implement an algorithm exponentially reducing the computation time required for detecting the focus plane. The method is validated on experimental holograms.

Development of an Efficient Acid Digestion Procedure Utilizing High-Pressure Asher Technique for the Determination of Iodine and Metallic Elements in Milk Powder

An effective wet digestion procedure for the determination of total iodine contents in milk powder samples was developed utilizing a high-pressure asher technique. The optimized method based on a two-stage digestion procedure. In the first stage, 500 mg samples were digested at 300 °C for 2 h using 15.2 mol L−1 HNO3 (5 mL) and 30 % H2O2 (3 mL). After the first digestion stage, digestion vessels were allowed to cool down and 1.2 mL of 20 % (w/v) Na2S2O8 solution was added as an additional oxidizing agent to the samples. After that, the vessels were closed, and they were heated at 100 °C for 30 min, resulting in clear and colorless sample solutions. Iodine concentrations in the digested samples were measured with inductively coupled plasma mass spectrometry. The accuracy of the optimized method was confirmed by analyzing milk powder reference material (BCR-151, milk powder). The obtained value for iodine (5.29 ± 0.37 mg kg−1, n = 6) was in good agreement with the certified value (5.35 ± 0.14 mg kg−1). Furthermore, the results obtained for reference material showed that the developed method can be applied also for the determination of other elements, e.g., copper, iron, and lead in the digested milk powder samples.

Effect of Bi 2O 3 proportion on physical, structural and electrical properties of zinc bismuth phosphate glasses

The variation in physical, structural and electrical properties has been studied as a function of Bi 2O 3 content in 20ZnF 2–(10 + x) Bi 2O 3–(70- x) P 2O 5, 0 ≤ x ≤ 10 mol% glasses, which were prepared by melt quenching technique and characterized by differential thermal analysis (DTA). Colorless samples, which have no absorption peaks, are obtained for 10 and 12 mol% of Bi 2O 3 and the glasses are slowly becoming brownish from 15 to 20 mol% of Bi 2O 3 which exhibit two absorption peaks at ~ 370 nm, ~ 450 nm correspond to Bi° transitions 4S 3/2 → 2P 3/2 and 4S 3/2 → 2P 1/2 respectively. The decrease in 3P 1 → 1S 0 transition of Bi 3+ photo luminescence emission for 18 and 20 mol% of Bi 2O 3 and increase in optical absorption area shows the reduction of Bi 3+ to Bi°. From FTIR studies it is observed that an addition of Bi 2O 3 decreases the P―O―P covalent bond by forming P―O―Bi bonds due to high polarizing nature of Bi 3+ ions. Dielectric parameters like ε', tan δ and a.c. conductivity σ ac are found to increase and activation energy for a.c. conduction is found to decrease with the increase in the concentration of Bi 2O 3. Density of defect energy states is found to increase for higher concentration of Bi 2O 3 and is discussed according to quantum mechanical tunneling (QMT) model.

An AFM contribution to the understanding of surface effects caused by ageing and cleaning on acrylic glass. The Shadows by Lourdes Castro, a case study

AbstractAtomic Force Microscopy (AFM) was used to study the ageing and cleaning effects on the surface of acrylic glass sheets (PMMA) like the ones used by the Portuguese artist Lourdes Castro. Measurements were done in transparent (colourless and blue) samples. The samples were aged in a SolarBox; cleaning and polishing products, similar to the ones applied by the artist, were used. From the AFM images the craze/scratch phenomena in the pristine samples surface was confirmed. The experiments led to an increase of the surface roughness, more pronounced for the polished samples due to the presence of granular features. These modifications are due to the interaction of the acrylic sheets with the polishing products, which seems to be stronger in the coloured samples. These findings are useful to define the best strategy to prolong the longevity of such materials, in particular the works of art created by Lourdes Castro. Copyright © 2010 John Wiley & Sons, Ltd.

Dielectric Property of Barium-Based Glasses Fabricated Using Thailand Resource

Barium-based glasses were fabricated using raw materials from the beneficiation of Thailand resources. Dopants of selected transition and rare-earth element oxides were added as coloring agents in order to produce materials of desired commercial applicability. Dielectric constants, refractive index and absorption spectra of the glass samples were measured. It was found that both dielectric constants and refractive indices increased when the dopants were added. Colorless barium-based glass samples were visually changed to green by additions of copper oxide, to yellow by iron oxide, to pinkish brown by manganese oxide, to pink by erbium oxide, and to lavender blue by neodymium. The fabrication of barium-based glass based on local raw materials is more economical compared to those using imported raw materials.

Effect of annealing at high pressures and temperatures on the defect-admixture structure of natural diamonds

The changes in the set and concentration of optically active defects in brown natural diamonds subjected to high pressure and high temperature annealing are studied. The darker brown color of the studied samples corresponds to stronger plastic deformation. The activation energy of the dissociation of the nitrogen pairs (defects A) decreases from 6.0 ± 0.4 eV in colorless samples with weak plastic deformation to 3.7 eV in dark brown samples with strong deformation. Possible defect transformation mechanisms are discussed.

Silver nanoparticles formation within unsaturated polyester/styrene resins induced by UV irradiation and thermal treatment

This article describes the formation of silver nanoparticles (NPs) within preformed unsaturated polyester/styrene resins in which the resulting color could be tuned by changing the silver load, time, and method used to grow the NPs. NP size and aggregation are responsible for the resulting sample color, and the samples present very good optical transparency. The silver ions were first added to the prepolymer that was crosslinked by free radical polymerization in the absence of light. NP formation was subsequently induced by submitting the transparent and colorless samples to heat or UV irradiation. Within the heated samples, isolated spherical particles ranging from 3 to 40 nm were observed. UV irradiation led to the formation of particle aggregates; however, as the exposure time was increased, silver NPs became well dispersed within the matrix within a particle diameter range of 9 to 24 nm. The particle formation is faster when induced by UV irradiation. Samples were also prepared by first dissolving rhodamine 6G in the resin. The emission bandwidth of samples prepared in this way showed a dependence on the silver particles amount and size. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

Amethyst and morion quartz gemstone raw materials from Turkey: color saturation and enhancement by gamma, neutron and beta irradiation

Color-enhancement investigations without using heating treatment from dull or pale to ideal saturation and/or changes to the formation of the rarer attractive colors are widely conducted to revalue abandoned gem material sources in the world. Such an investigation is carried out on pale or dull purple-colored amethyst and smoky-colored morion samples, which are two important gem species of the crystalline quartz (SiO2) mineral that are currently abandoned in natural deposits in Turkey because of their unattractive coloration. The results of color enhancements observed on these samples, after irradiation with artificial gamma, neutron and beta beams, were examined by comparing with samples with the ideal color saturation and also with colorless samples, using optical absorption (OA) and radioluminescence (RL) spectroscopy. The ICP-AES analyses reveal that the main impurity elements of over 100 ppm in abundance in these quartz species are aluminum, iron and titanium for amethyst, and aluminum, iron, titanium and manganese for morion. The OA spectra indicate that vivid purple coloration of amethyst is due to the transmittance at about 395–420 nm band gap as a result of absorbance peaks at 375, 480 and 530 nm. These absorbances may be related to the unusual oxidized small proportions of certain impurity ions, after being exposed mainly to gamma irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Fe(IV) from the total iron, respectively. However, the RL spectroscopy of amethyst samples before and after they were exposed to artificial gamma, neutron and beta radiation beams demonstrates that the ions most affected by irradiation are Fe(IV) first and Al(IV) and Ti(V) second, and these ions represent the RL peaks at 600, 720 and 495 nm, respectively. The OA spectra indicate that dark smoky coloration in morion is due to a lack of transmittance at the visible region as a result of the absorbance peaks at 375, 450–490, 620 and 730 nm. These absorbances also may be related to the unusual oxidized small proportions of certain impurity ions by irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Mn(III) from the total manganese, respectively. In addition, the buoyancies of these absorbance peaks in the visible region produce the color hues between light smoky and dark smoky colorations in morion samples. These oxidized ion states are more resistant and stable against environmental destructive conditions in comparison with amethyst. Thus, the dark smoky coloration of morion becomes dull or pale after relatively longer periods. But, the RL spectroscopy of morion before and after being exposed to gamma, neutron and beta irradiation beams demonstrates that the most induced ions from the irradiation are Mn(III) and Al(IV) first and Ti(V) second. These ions represent the RL peaks at about 400, 720 and about 500 nm, respectively.