Sorption specifics of volatile amines on thin films of acid-base indicators

The sorption specifics of various classes of volatile amines on thin films of organic acid-base indicators is studied by piezoelectric quartz micro weighing. The differences in the sorption behavior of amines on indicator films obtained from ethanolic and acetone solutions are revealed. The influence of the indicator acidity on the sorption of amine vapors is studied. An array of piezoelectric sensors based on thin films of acid-base indicators is developed and an algorithm of registering their responds to amines of different structures is proposed for their separate determination in a mixture.     

Use of biogenic amines to evaluate spoilage in plaice (Pleuronectes platessa) and whiting (Merlangus merlangus)

Fish muscle decarboxylases generate biogenic amines during spoilage. We monitored spoilage in plaice and whiting by assaying biogenic amines represented by the amine index (AI), and by using expert assessors to determine a freshness index (FI) for each fish. First we characterized the assessor- and fish species-related effects on FI, and then we sought to correlate changes in AI and FI by statistical data analysis. We propose rejection limits on the basis of our findings.     

Phthalocyanines as oxidation-reduction indicators

Analytical and Bioanalytical Chemistry -     

Phthalocyanines as oxidation-reduction indicators

Summary Copper phthalocyanine tetrasulphonic acid has been found to work satisfactorily as an inside indicator in the cerimetric titration of hydro-quinone and metol. It has the advantage that the indicator correction in titrations with 0.01 N solutions of ceric sulphate is much less than with the ferroin indicator, amounting to only 0.02 ml for two drops of the indicator solution.Part II: See Z. analyt. Chem. 163, 1 (1958).     

Aromatic amines as nucleophiles in the Bargellini reaction

Aromatic amines can be employed in the Bargellini reaction to generate useful intermediates. Rapid, practical access to functionalised, privileged structures may have significant utility in the synthesis of drug-like molecules. An improved synthesis of carfentanil analogues illustrates this point.     

Chelated amines as ligands in olefin hydrogenation catalysts

Activities of catalysts obtained in the reaction of [MCl(C₈H₁₄)₂]₂, (M=Rh, Ir) with amines NH₂(CH₂)_nNH₂, (N=2–5), (CH₃)₂NC₂H₄(CH₃)₂ and 1.8=diaminonaphthalene have been examined. The most efficient catalyst was obtained with 1.3-diaminopropane.

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, [MCl(C₈H₁₄)₂]₂. (M=Rh, Ir) NH₂(CH₂)_nNH₂, (n=2–5). (CH₃)₂NC₂H₄(CH₃)₂ 1,8-. , 1,3-.

     

Triphenylmethane dyes as redox indicators in dichrometry

Summary The use of some triphenylmethane dyes, Erioglaucine A, Eriogreen B, Xylenecyanol FF, Setoglaucine O, Setocyanine Supra, Fast Green FCF, and Night Blue as redox indicators in the dichrometric titration of iron(II), ferrocyanide, uranium(IV), molybdenum(V), and hydroquinone in hydrochloric acid, sulphuric acid and perchloric acid media has been studied. Conditions for the satisfactory titrations employing these indicators have been established.

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Triphenylmethanfarbstoffe als Redoxindicatoren bei Titrationen mit Dichromat

Zusammenfassung Bei der Titration von Eisen(II), Hexacyanoferrat(II), Uran(IV), Molybdän(V) und Hydrochinon mit Dichromat in salz-, schwefeloder perchlorsaurer Lösung wurden folgende Triphenylmethanfarbstoffe als Indicatoren verwendet: Erioglaucin A, Eriogrün B, Xylolcyanol FF, Setoglaucin O, Setocyanin Supra, Echtgrün FCF und Nachtblau. Die entsprechenden Titrationsbedingungen werden mitgeteilt.

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We are grateful to the Council of Scientific & Industrial Research, India, for the award of a Junior Research Fellowship to one of us (V. V. S. E. D.).     

N-substituted phenothiazines as redox indicators in bromatometry

Diethazine hydrochloride, butaperazine dimaleate, trifluoperazine hydrochloride, promethazine hydrochloride, prochlorperazine maleate and chlorpromazine hydrochloride have been studied as indicators in bromate titration of quinol, metol and ascorbic acid. They give a very sharp reversible colour change at the equivalence point. Their formal potentials have been determined. A simple but accurate method for the estimation of quinol and metol is reported.     

Glass transitions in starch,gluten and bread as measured

Dielectric Spectroscopy (DS) and Thermomechanical Analysis (TMA) were used to identity the glass transition temperature (T _g) of native wheat starch, vital wheat gluten and a commercial bread, in response to changes in moisture content. An open-ended coaxial probe technique was used to measure the permittivity or dielectric constant (?′) and the loss factor (?″) as functions of moisture, for 2.45 GHz frequency, at constant density and temperature. Plots of ?′ and ?″ as functions of moisture content showed dramatic changes in mobility-based dielectric properties, which occur upon transition from the glassy solid to the rubbery liquid state. The modified TMA method can measure the change in viscoelastic properties aroundT _g. This study further confirms that synthetic polymer science principles can be applied to food systems.     

Isotopes in groundwater as indicators of climate changes

Isotopes of the water molecule (δ¹⁸O and δ²H) are a well-used tool for investigating groundwater origin and history (i.e. tracing the recharge conditions over time, processes occurring during infiltration of rainwater towards aquifers and those involved in the water-rock interaction, and mixing of different waters).This review covers several large European aquifers (Portugal, France, UK, Switzerland, Germany, Hungary, and Poland), which were investigated in terms of their recharge conditions, and the story of the groundwater at a large scale, involving recent, Holocene and Pleistocene components and their eventual mixing.     

Biogenic Silver Nanoparticles from Iris tuberosa as Potential Preservative in Cosmetic Products

Biogenic-silver nanoparticles emerge as new nanosilver platforms that allow us to obtain silver nanoparticles via “green chemistry”. In our study, biogenic-silver nanoparticles were obtained from Iris tuberosa leaf extract. Nanoparticles were characterized by a UV-vis spectroscopy, dynamical light scattering technique. The transmission electron microscope revealed spheric and irregular nanoparticles with 5 to 50 nm in diameter. Antimicrobial properties were evaluated against typical microbial contaminants found in cosmetic products, showing high antimicrobial properties. Furthermore, natural moisturizing cream was formulated with biogenic-silver nanoparticles to evaluate the preservative efficiency through a challenge test, indicating its promising use as preservative in cosmetics.     

N-substituted phenothiazines as indicators in titrations with chloramine-T

Trifluoperazine dihydrochloride, butaperazine dimaleate, promethazine hydrochloride, diethazine hydrochloride, prochlorperazine maleate and chlorpromazine hydrochloride have been studied as redox indicators in titrations of hydroquinone, metol and ascorbic acid with chloramine-T. The end-points obtained are sharper than with conventional indicators. The molar absorptivities of the oxidized indicators are reported. Simple but accurate methods for the determination of hydroquinone and metol are described.     

Biogenic Silver Nanoparticles as a Stress Alleviator in Plants: A Mechanistic Overview

Currently, the growth and yield of crops are restrained due to an increase in the occurrence of ecological stresses globally. Biogenic generation of nanomaterials is an important step in the development of environmentally friendly procedures in the nanotechnology field. Silver-based nanomaterials are significant because of their physical, chemical, and biological features along with their plentiful applications. In addition to useful microbes, the green synthesized Ag nanomaterials are considered to be an ecologically friendly and environmentally biocompatible method for the enhancement of crop yield by easing stresses. In the recent decade, due to regular droughts, infrequent precipitation, salinity, and increased temperature, the climate alternation has changed certain ecological systems. As a result of these environmental changes, crop yield has decreased worldwide. The role of biogenic Ag nanomaterials in enhancing methylglyoxal detoxification, antioxidant defense mechanisms, and generating tolerance to stresses-induced ROS injury has been methodically explained in plants over the past ten years. However, certain studies regarding stress tolerance and metal-based nanomaterials have been directed, but the particulars of silver nanomaterials arbitrated stresses tolerance have not been well-reviewed. Henceforth, there is a need to have a good understanding of plant responses during stressful conditions and to practice the combined literature to enhance tolerance for crops by utilization of Ag nanoparticles. This review article illustrates the mechanistic approach that biogenic Ag nanomaterials in plants adopt to alleviate stresses. Moreover, we have appraised the most significant activities by exogenous use of Ag nanomaterials for improving plant tolerance to salt, low and high temperature, and drought stresses.     

Phenols and aromatic amines as thermal stabilizers in polyolefin processing

Scavenging of C‐ and O‐centered free radicals is mandatory in processing stabilization of polypropylene. Phenolic antioxidants act principally as O‐radical scavengers only. Aromatic amines, N,N'‐disubstituted 1,4‐phenylenediamines (PD) and 4,4'disubstituted diphenylamines (DPA), scavenge both C‐ and O‐centered radicals and have consequently a broader activity spectrum. PD cannot be used, however, in polypropylene because of formation of strongly discoloring and staining sacrificial transformation products. Such products formed from DPA have even more discoloring properties. A good processing stability and acceptable extent of discoloration can be achieved by blends of phenols with 4,4'‐di‐tert.octyl DPA. The effect is considered as a beneficial cooperation between the two chain‐breaking antioxidants involving interactions with amine‐based transformation products.