A fractal analysis of skin pigmented lesions using the novel tool of the variogram technique

The incidence of the cutaneous malignant melanoma is increasing rapidly in the world [Ferlay J, Bray F, Pisani P, et al. GLOBOCAN 2000: Cancer incidence, mortality and prevalence worldwide, Version 1.0 IARC Cancer Base no. 5. Lyon: IARC Press, 2001]. The therapeutic address requires a method having high sensitivity and capability to diagnose such disease at an early stage. We introduce a new diagnostic method based on non-linear methodologies. In detail we suggest that fractal as well as noise and chaos dynamics are the most important components responsible for genetic instability of melanocytes. As consequence we introduce the new technique of the variogram and of fractal analysis extended to the whole regions of interest of skin in order to obtain parameters able to identify the malignant lesion. In a preliminary analysis, satisfactory results are reached.     

Formation and nitration heats for 3-nitro-4-chloro- and 3,5-dinitro-4-chloro-benzotrifluoride. Dinitration reaction investigation

Although various authors have determined the heats of combustion of many halogen derivatives we still do not have at our disposal data concerning the 3-nitro-4-chlorobenzotrifluoride and the 3,5-dinitro-4-chlorobenzotrifluoride.The object of this study has been that of determining the thermochemical constants for the above mentioned compounds. The values of the heats of combustion and of formation have been determined experimentally and from them the heats of nitration. These data and those determined with Handrick's method (group's energy contribution) have been compared with the heats of reaction carrying the nitration into an adiabatic system.Afterwards it has been investigated how to get the maximum output for the dinitro production. Data and considerations are reported.     

Sample preparation for the analysis of flavors and off-flavors in foods

Off-flavors in foods may originate from environmental pollutants, the growth of microorganisms, oxidation of lipids, or endogenous enzymatic decomposition in the foods. The chromatographic analysis of flavors and off-flavors in foods usually requires that the samples first be processed to remove as many interfering compounds as possible. For analysis of foods by gas chromatography (GC), sample preparation may include mincing, homogenation, centrifugation, distillation, simple solvent extraction, supercritical fluid extraction, pressurized-fluid extraction, microwave-assisted extraction, Soxhlet extraction, or methylation. For high-performance liquid chromatography of amines in fish, cheese, sausage and olive oil or aldehydes in fruit juice, sample preparation may include solvent extraction and derivatization. Headspace GC analysis of orange juice, fish, dehydrated potatoes, and milk requires almost no sample preparation. Purge-and-trap GC analysis of dairy products, seafoods, and garlic may require heating, microwave-mediated distillation, purging the sample with inert gases and trapping the analytes with Tenax or C18, thermal desorption, cryofocusing, or elution with ethyl acetate. Solid-phase microextraction GC analysis of spices, milk and fish can involve microwave-mediated distillation, and usually requires adsorption on poly(dimethyl)siloxane or electrodeposition on fibers followed by thermal desorption. For short-path thermal desorption GC analysis of spices, herbs, coffee, peanuts, candy, mushrooms, beverages, olive oil, honey, and milk, samples are placed in a glass-lined stainless steel thermal desorption tube, which is purged with helium and then heated gradually to desorb the volatiles for analysis. Few of the methods that are available for analysis of food flavors and off-flavors can be described simultaneously as cheap, easy and good.     

Alkyltrimethylammonium surfactant-mediated extractions: characterization of surfactant-rich and aqueous layers, and extraction performance

Most surfactants employed for extraction purposes contain strongly absorbing chromophores, and therefore cannot be used with the ultraviolet-visible HPLC detector because of the high background created. Alkyltrimethylammonium surfactants, which do not have strongly absorbing chromophores, have shown promise as an extractant compatible with HPLC-ultraviolet-visible detection. In our extraction procedure, alkyltrimethylammonium surfactants are added to a sample containing organic analytes in distilled water. Sodium chloride is next added, then the entire sample is shaken. Before centrifugation, 1-octanol is added to aid in the two phase formation of surfactant-rich and aqueous phases. In this paper, we present the results of our studies on the extraction behavior of an alkyltrimethylammonium surfactant technique using various organic compounds as test probes. Specifically studied are the extraction behavior of organic bases, isomers of varying polarity and a zwitterionic species that has different charges at various pH values. Results from multiple extractions to obtain quantitative recovery of analytes is also presented. The composition of each phase is elucidated through the interpretation of data obtained from thermogravimetric and carbon, hydrogen and nitrogen (CHN) instrumentation.     

Analysis of nickel-niobium alloys by inductively coupled plasma optical emission spectrometry

Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to the analysis of major and minor elements of Ni-Nb alloys obtained by aluminothermic reduction process. Digestion of samples was made using a mixture of HF+HNO₃. Minor and trace elements were determined without matrix separation. The precision for all constituents was <3%. Recoveries for the analyte-spiked samples were 95%.     

O-Alkylation of a lignite humic acid by phase-transfer catalysis

A mild phase-transfer catalytic reaction has been conducted to O-alkylate the acidic functions of a lignite humic acid (HA), using tetrabutylammonium hydroxide as the phase-transfer catalyst. The HA acidic functional groups were made to react, in tetrahydrofuran, by nucleophilic substitution with several alkyl halides—methyl iodide, and ethyl, propyl, and butyl, and benzyl bromide. The occurrence of the O-alkylation reaction was assessed by elemental analysis and ¹H NMR, CPMAS ¹³C NMR, and FTIR spectroscopy. Bonding of alkyl groups increased the carbon and hydrogen content and the H/C ratios of all the humic reaction products. Increased nitrogen in the reaction products suggested incomplete removal of the phase-transfer catalyst after purification of the alkylated HA. ¹H NMR and CPMAS ¹³C NMR spectra of alkylated products provided evidence of the successful occurrence of the alkylation reactions. Infrared spectra confirmed the NMR results, revealing the characteristic absorption of newly formed alkyl and aryl ethers and esters in the alkylated products and C–H stretching in the aromatic ring of the benzylated derivative. These findings indicate that humic matter can be successfully alkylated with several different alkylating groups by catalysed phase-transfer reaction. This O-alkylation reaction has the advantage of being mild, versatile, and high-yielding compared with traditional methylation reactions applied to HA. The possibility of introducing different alkyl groups into the HA by a mild phase-transfer reaction may become useful by enabling improved fractionation of humic supramolecular associations and further understanding of the molecular nature of humic substances.     

Gold nanoparticle-initiated free radical oxidations and halogen abstractions

We report on the use of EPR spectroscopy and spin trapping technique to detect free radical intermediates formed in the presence of gold nanoparticles. Phosphine- and amine-protected gold nanoparticles were found to initiate air oxidation of organic substrates containing active hydrogen atoms, such as amines and phosphine oxides. Nanoparticles protected by stronger bound ligands (e.g., thiols) were inactive in these reactions. We also found that gold nanoparticles are able to abstract a halogen atom from the halogenated compounds, presumably due to the high affinity of gold metal for halogens. Reaction of Au nanoparticles with chloroform showed an unusual inverse isotope effect. The trichloromethyl spin adduct was observed when Au nanoparticles were mixed with CDCl(3) but not with CHCl(3). This unexpected behaviour suggests that C-H bond breaking is not the rate-determining step in Au-initiated hydrogen abstraction.     

Detection of hazelnut oil in virgin olive oil by assessment of free sterols and triacylglycerols

Free sterols were evaluated as factors for discriminating between genuine virgin olive oil and hazelnut-mixed virgin olive oil. Numeric analyses of the results amplified the differences between groups. The application of this method to virgin olive oil samples and their mixtures with 10% hazelnut oil distinguished between genuine and nongenuine virgin olive oil with statistical certainty. Triacylglycerol analysis was tested for the same purpose by using parameter deltaECN42, but although it possessed a discriminating capacity, it alone could not distinguish the aforementioned groups with sufficient certainty. Free delta7-sterols data were combined with deltaECN42 data into a single discriminating function to improve differentiation and bring more ruggedness, and for detection of low amounts (10%) of hazelnut oil in virgin olive oil. In fact, the values obtained by addition of delta7-sterol data and deltaECN42 data showed a higher discriminating capacity than single parameters. In a single operation the method produced all the oil fractions necessary for analysis of free sterols and triacylglycerols with ECN42. Solid-phase extraction was applied in substitution of traditional chromatography on a silica column.