Abstract  This loose-leaf collection was published under the auspices of the Toxic Substance Control Committee of the German Research Association. It contains basic information on approx. 300 substances (chemicals, gases, fumes, silica, asbestos, man-made mineral fibres, cutting fluids). Supplement 11 had one chapter devoted to passive smoking. Supplement 12 provides additional studies on: aluminium fumes and dust; acetaldehyde (update); ammonia (update); 1,4 and 2,4-butanesultone; 2-methyl-4-chloroaniline; dichloromethane (update); 3-3'-dimethoxybenzidine; 3-3'-dimethylbenzidine; dipropylene glycol monomethyl ether; ethyl acrylate; 2-nitro-p-phenylenediamine; o-toluidine; vinyl chloride; chlorodifluoromethane; 4-amino-2-nitrophenol; xylene.

Abstract  Isopropyl alcohol(IPA) is widely used as additive to enhance surface structure and reduce the reflectivity of silicon wafers in alkaline texturing process of mono-crystalline silicon solar cells currently. However, due to its low boiling point and high volatilization, some negative effects are brought into large scale production especially in stability, cost and environment. In this paper, Dipropylene glycol(DPG) which has relative high boiling point was tried to substitute IPA as texturing solution additive. The influences of concentration of DPG and NaOH on etching rate, surface morphology and reflectance spectrum were investigated. It is obviously observed that the silicon is prevented from etching reaction by the existence of DPG. The best weight reflectance of 13.6% is obtained on mono-crystalline silicon surface by an optimized solution of 1 wt% NaOH and 1 wt% DPG at 80 degrees C for 20 minutes. Finally, the influencing mechanism of DPG was also discussed in detail.

Abstract  Cleaning is a large enterprise involving a large fraction of the workforce worldwide. A broad spectrum of cleaning agents has been developed to facilitate dust and dirt removal, for disinfection and surface maintenance. The cleaning agents are used in large quantities throughout the world. Although a complex pattern of exposure to cleaning agents and resulting health problems, such as allergies and asthma, are reported among cleaners, only a few surveys of this type of product have been performed. This paper gives a broad introduction to cleaning agents and the impact of cleaning on cleaners, occupants of indoor environments, and the quality of cleaning. Cleaning agents are usually grouped into different product categories according to their technical functions and the purpose of their use (e.g. disinfectants and surface care products). The paper also indicates the adverse health and comfort effects associated with the use of these agents in connection with the cleaning process. The paper identifies disinfectants as the most hazardous group of cleaning agents. Cleaning agents contain evaporative and non-evaporative substances. The major toxicologically significant constituents of the former are volatile organic compounds (VOCs), defined as substances with boiling points in the range of 0 degree C to about 400 degrees C. Although laboratory emission testing has shown many VOCs with quite different time-concentration profiles, few field studies have been carried out measuring the exposure of cleaners. However, both field studies and emission testing indicate that the use of cleaning agents results in a temporal increase in the overall VOC level. This increase may occur during the cleaning process and thus it can enhance the probability of increased short-term exposure of the cleaners. However, the increased levels can also be present after the cleaning and result in an overall increased VOC level that can possibly affect the indoor air quality (IAQ) perceived by occupants. The variety and duration of the emissions depend inter alia on the use of fragrances and high boiling VOCs. Some building materials appear to increase their VOC emission through wet cleaning and thus may affect the IAQ. Particles and dirt contain a great variety of both volatile and non-volatile substances, including allergens. While the volatile fraction can consist of more than 200 different VOCs including formaldehyde, the non-volatile fraction can contain considerable amounts (> 0.5%) of fatty acid salts and tensides (e.g. linear alkyl benzene sulphonates). The level of these substances can be high immediately after the cleaning process, but few studies have been conducted concerning this problem. The substances partly originate from the use of cleaning agents. Both types are suspected to be airway irritants. Cleaning activities generate dust, mostly by resuspension, but other occupant activities may also resuspend dust over longer periods of time. Personal sampling of VOCs and airborne dust gives higher results than stationary sampling. International bodies have proposed air sampling strategies. A variety of field sampling techniques for VOC and surface particle sampling is listed.

Abstract  Using data available in the Products Register at the Swedish National Chemical Inspectorate, an analysis was undertaken of the occurrence and turnover of glycol ethers in Sweden between 1986 and 1993. The most commonly used glycol ethers during 1991 and 1992 were propylene-glycol-monomethyl-ether (107982), ethylene-glycol-monobutyl-ether (111762), diethylene-glycol-monobutyl-ether (112345), and dipropylene-glycol-monomethyl-ether (20324327). Also used to a large extent were diethylene-glycol-monobutyl-ether-acetate (124174) (DEGBEA), diethylene-glycol-monoethyl-ether-acetate (112152), diethylene-glycol-monomethyl-ether (111773), and diethylene-glycol-monoethyl-ether (111900). The use of ethylene-glycol-monoethyl-ether (110805) and ethylene-glycol-monoethyl-ether-acetate (111159) decreased markedly from 1992 to 1993 while the use of all the other glycol ethers increased. The authors suggest that the marked increase in the use of ethylene-glycol-monomethyl-ether (109864) between 1992 and 1993 warrants further study.

Abstract  The appropriate combination of viscosifier and coviscosifier is a very important factor in the control of the viscosity and adhesion properties of chemical decontamination gels. A chemical decontamination gel was prepared by adding gelling agents composed of a pyro Si viscosifier and PEG-based non-ionic coviscosifier (tripropylene glycol butyl ether and tripropylene glycol dodecyl ether) into a Ce(IV) solution stabilized in concentrated nitric acid. The decontamination and rheological behaviours, along with the drying behaviours of a chemical gel for SUS 304 metallic surfaces contaminated with Co and Cs radionuclides were investigated. A chemical gel containing a 0.5 wt % tripropylene glycol dodecyl ether coviscosifier was more effective in terms of the rheological and drying-detachment properties and the radionucleide decontamination effectiveness in particular, compared to tripropylene glycol butyl ether.

Abstract  RPSL-01 type photosensitive resin for Stereo lithography was prepared with 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (UVR 6110), bisphenol A type epoxy diacrylate (EA-612), tripropylene glycol diacrylate (TPGDA), pentaerythritol triacrylate(PETA), triethylene glycol divinyl ether (DVE-3), benzil dimethyl ketal (Irgacure651) and a mixture of triarylsulfonium hexafluoroantimonate salts (UVI-6976) as raw materials. Some properties of the photosensitive resin were investigated. The viscosity of the photosensitive resin at 30 degrees C was 425mP(a).S, The glass transition temperature (Tg) of the UV-cured specimen was 47 degrees C, and the weight loss of the UV-cured specimen at 200 degrees C was less than 5%. The photosensitive resin and its UV-cured specimen were also characterized by infrared (IR).

Abstract  A new set of molar heat capacity data for aqueous {2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) + glycol} at (30 to 80)degrees C and different concentrations (4% to 16% by weight TRIS or 56% to 44% by weight water, in a fixed amount of glycol - 40% by weight) were gathered via reliable measurement method and are presented in this report. The glycols considered were diethylene glycol (DEG), triethylene glycol (TEG), tetraethylene glycol (T(4)EG), propylene glycol (PG), dipropylene glycol (DPG), and tripropylene glycol (TPG). The 198 data points gathered fit the equation, C-p = C-p,C-a + B(1)m + B(2)m(2) + B(3)m(3), where C-p and C-p,C-a are the molar heat capacities of the (TRIS + glycol + water) and (water + glycol) systems, respectively, B-i the temperature-dependent parameters, and m the mole TRIS per kilogram (glycol + water). The overall average absolute deviation (AAD) of the experimental data from the corresponding values calculated from the correlation equation was 0.07%. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  Composites based on unsaturated polyester (UPe) resins and fumed silica AEROSIL (R) RY 50, NY 50, RX 50 and NAX 50, as well as graphite, TiO2 or organically modified clay CLOISITE 30B were prepared in order to investigate the influence of reinforcing agents on the mechanical properties of composites. Unsaturated polyester resins were synthesized from maleic anhydride and products of glycolysis, obtained by depolymerization of poly(ethylene terephthalate) with dipropylene glycol (UPe1 resin) and triethylene glycol (UPe2 resin) in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by FTIR spectroscopy, acid and hydroxyl values, and their mechanical properties were also examined. Significant increase of the tensile modulus, tensile strength and decrease of the elongation at break was observed for composites prepared after addition of 10 wt.% of graphite or 10 wt.% of TiO2 to the UPe resins, indicating strong interaction between matrix and filler particles. On the other hand, nanocomposites prepared using UPe2 and hydrophobically modified silica nanoparticles showed lower tensile strength and tensile modulus than polymer matrix. The presence of CLOISITE 30B had no significant influence on the mechanical properties of UPe1, while tensile strength and tensile modulus of UPe2 increased after adding 10 wt.% of clay.

Abstract  The triethylene glycol and tripropylene glycol derivatives terminated with the CO2-philic phosphoryl groups, named 2-(2-(2-((2-ethylhexoxy(methoxy)phosphoryl)oxy)-ethoxy)ethoxy)ethyl 2-ethylhexyl methyl phosphate (EG3EH) and 2-(2-(2-((2-ethylhexoxy(methoxy)phosphoryl)oxy)propoxy)-propoxy)propyl 2-ethylhexyl methyl phosphate (PG3EH), were synthesized and characterized. The solubilities of EG3EH and PG3EH in scCO(2) were determined by a static method at temperatures from (313 to 333) K and over a pressure range of (10 to 19) MPa. The values calculated by the Bartle semiempirical model exhibited good agreement with the experimental data.

Abstract  Porous and hollow particles are widely used in pharmaceuticals, as solid phases for chromatography, as catalyst supports, in bioanalytical assays and medical diagnostics, and in many other applications. By controlling size, shape, and chemistry, it is possible to tune the physical and chemical properties of the particles. In some applications of millimeter-scale hollow shells, such as in high energy density physics, controlling the shell thickness uniformity (concentricity) and roundness (sphericity) becomes particularly important. In this work, we demonstrate the feasibility of using electric field-driven droplet centering to form highly spherical and concentric polymerizable double emulsion (DE) droplets that can be subsequently photopolymerized into polymer shells. Specifically, when placed under the influence of an similar to 6 x 10(4) V-rms/m field at 20 MHz, DE droplets, consisting of silicone oil as the inner droplet and tripropylene glycol diacrylate with a photoinitiator in N,N-dimethylacetamide as the outer droplet, suspended in ambient silicone oil, were found to undergo electric field-driven centering into droplets with >= 98% sphericity and similar to 98% concentricity. The centered DE droplets were photopolymerized in the presence of the electric field. The high degrees of sphericity and concentricity were maintained in the polymerized particles. The poly(propylene glycol diacrylate) capsules are just within the sphericity requirements needed for inertial confinement fusion experiments. They were slightly outside the concentricity requirement. These results suggest that electric field-driven centering and polymerization of double emulsions could be very useful for synthesizing hollow polymer particles for applications in high energy density physics experiments and other applications of concentric polymer shells.

Abstract  Combustion behavior of various oxygenated fuels has been studied in a DAF heavy-duty (HD) direct-injection (DI) diesel engine. From these fuels, it is well-known that they lead to lower particle (PM) emissions; however, for a given fuel oxygen mass fraction, there are significant differences in PM reduction. Although this can be traced back to the specific molecular structure of the oxygenate in question, no consensus can be found in the literature as to the explanation hereof. In this study, the sooting tendency (smoke number) of three oxygenates [viz., tripropylene glycol methyl ether (TP), dibutyl maleate (DB), and cyclohexanone (X1)] was compared to that of commercial diesel fuel (EN590, D). The results suggest that the cetane number (CN) (i.e., fuel reactivity) may play an important role. More specifically, the low reactive oxygenate X1, with its cyclic carbon chain, was found to perform exceptionally well compared to the more reactive linear and branched oxygenates DB and TP, respectively. Cyclic oxygenates are abundant in nature. Cellulose, the most common organic compound on earth, is the best-known example. Although it is not trivial, liquid cyclic oxygenates can be made from lignocellulosic biomass. Particularly, the production of C6 oxygenates (e.g., guaiacol, cyclohexanone, phenol, etc.), which can be derived from lignin, is the subject of current investigation. Fuels produced from such biomass (e.g., plant waste or the nonedible part of plants) are referred to as second-generation biofuels and are expected to play a pivotal role in the near future.

Abstract  Densities and viscosities at T = 293.15, 298.15 and 303.15 K in the binary liquid mixtures of ethyl tert-butyl ether (ETBE) with propylene glycol monomethyl ether (PM), dipropylene glycol monomethyl ether (DPM) and tripropylene glycol monomethyl ether (TPM) have been measured over the entire mixture compositions. These data have been used to compute the excess molar volumes (V E), the excess energies of activation for viscous flow ΔG E, the deviations in the viscosity (Δη) from a mole fraction average and the Grunberg–Nissan interaction parameters (d 12). The values of V E, Δη, ΔG E and d 12 are negative over the entire range of composition for all the studied binary mixtures. The changes of V E, Δη, ΔG E and d 12 with variations in the composition and the chain-length of the alkyl groups in the alkoxypropanol molecules are discussed in terms of the intermolecular interactions.

Abstract  Speeds of sound have been measured in dipropylene glycol tert-butyl ether with methanol, 1-propanol, 1-pentanol, and 1-heptanol at 298.15 K over the entire composition range using a NUSONIC velocimeter based on sing-around technique. The isentropic compressibility KS for all mixtures were estimated by combining the densities derived from excess molar volumes and the speeds of sound. The molar volume were multiplied by the isentropic compressibilities to obtain estimates of K-s.m. The corresponding quantities K-s,m(E) have also been calculated. The K-S.m(E) values are negative over the entire range of composition for all mixtures with the exception of I-pentanol which changes sign from negative to positive. The magnitude of K-S,m(E) increases with the number of carbon atoms in the n-alcohol. The deviations u(D) of the speeds of sound from the values calculated for ideal mixtures have been obtained for all measured mole fractions. The behavior of K-S.m(E) and u(D) with composition and the number of carbon atoms in the alcohol molecule is discussed.

Abstract  The principal aim of the study was to estimate the level of exposure to organic solvents of graffiti removers, and to identify the chemicals used in different cleaning agents. A secondary objective was to inform about the toxicity of various products and to optimise working procedures.

Exposure to organic solvents was determined by active air sampling and biological monitoring among 38 graffiti removers during an 8-h work shift in the Stockholm underground system. The air samples and biological samples were analysed by gas chromatography. Exposure to organic solvents was also assessed by a questionnaire and interviews.

Solvents identified were N-methylpyrrolidone (NMP), dipropylene glycol monomethyl ether (DPGME), propylene glycol monomethyl ether (PGME), diethylene glycol monoethyl ether (DEGEE), toluene, xylene, pseudocumene, hemimellitine, mesitylene, ethylbenzene, limonene, nonane, decane, undecane, hexandecane and gamma-butyrolactone. The 8-h average exposures [time-weighted average (TWA)] were below 20% of the Swedish permissible exposure limit value (PEL) for all solvents identified. In poorly ventilated spaces, e.g. in elevators etc., the short-term exposures exceeded occasionally the Swedish short-term exposure limit values (STEL). The blood and urine concentrations of NMP and its metabolites were low. Glycol ethers and their metabolites (2-methoxypropionic acid (MPA), ethoxy acetic acid (EAA), butoxy acetic acid (BAA), and 2-(2-methoxyethoxy) acetic acid (MEAA)) were found in low concentrations in urine. There were significant correlation between the concentrations of NMP in air and levels of NMP and its metabolites in blood and urine. The use of personal protective equipment, i.e. gloves and respirators, was generally high.

Many different cleaning agents were used. The average exposure to solvents was low, but some working tasks included relatively high short-term exposure. To prevent adverse health effects, it is important to inform workers about the health risks and to restrict the use of the most toxic chemicals. Furthermore, it is important to develop good working procedures and to encourage the use of personal protection equipment.

Abstract  The addition of oxygen-bearing compounds to diesel fuel considerably reduces particulate emissions. TGME and DBM have been identified as possible diesel additives based on their physicochemical characteristics and performance in engine tests. Although these compounds will reduce particulate emissions, their potential environmental impacts are unknown. As a means of characterizing their persistence in environmental media such as soil and groundwater, we conducted a series of biodegradation tests of DBM and TGME. Benzene and methyl tertiary butyl ether (MTBE) were also tested as reference compounds. Primary degradation of DBM fully occurred within 3 days, while TGME presented a lag phase of approximately 8 days and was not completely degraded by day 28. Benzene primary degradation occurred completely by day 3 and MTBE did not degrade at all. The total mineralized fractions of DBM and TGME achieved constant values as a function of time of approximately 65% and approximately 40%, respectively. Transport predictions show that, released to the environment, DBM and TGME would concentrate mostly in soils and waters with minimal impact to air. From an environmental standpoint, these results combined with the transport predictions indicate that DBM is a better choice than TGME as a diesel additive.

Abstract  A mixture of coal processing agents, namely crude-MCHM (primarily 4-methylcyclohexanemethanol) and stripped-PPH (primarily dipropylene glycol phenyl ether and propylene glycol phenyl ether) spilled into the Elk River near Charleston, West Virginia in January 2014. The spill resulted in a do-not-use ban on drinking water for up to 10days. Studies were undertaken to determine the potential for aerobic biodegradation of crude-MCHM and PPH in the riverine system and in the sewage treatment plant postflushing of affected water lines. Complete biotransformation of crude-MCHM occurred only when MCHM was initially <6mgL-1. When both PPH and crude-MCHM were present, biotransformation of both compounds only occurred when MCHM was initially <2.3mgL-1 and PPH was <3mgL-1. Limited conversion of PPH was typically observed (<40%). Estimated maximum specific biodegradation rates were 0.087mg cis-MCHM (mgbiomassh)-1 and 0.23mg trans-MCHM (mgbiomassh)-1. The estimated half saturation constants were 2.7mg cis-MCHM L-1 and 10.5mg trans-MCHM L-1. Toxicity studies with agar diffusion plates and ToxTrac indicate both MCHM and PPH exhibit toxicity to Elk River microcosm cultures and that microbiological degradation of MCHM and PPH may generate more toxic products. Phylogenetic analysis of sediments and biodegradation microcosm cultures identified methanotrophs, methylotrophs, and organisms associated with xenobiotic biodegradation, acid mine drainage, and sulfidic mine tailings. These studies can be used to understand the likelihood of biological degradation of MCHM and PPH in environmental and treatment systems.

Abstract  Anthramycin (ANT) is a member of the pyrolobenzodiazepine family and is a potent cytotoxic agent. Previously, we reported the topical delivery of ANT from a range of solvents that may also act as skin penetration enhancers (SPEs). The skin penetration and uptake was monitored for simple solutions of ANT in propylene glycol (PG), dipropylene glycol (DiPG), Transcutol P (TC), isopropyl myristate (IPM), propylene glycol monocaprylate (PGMC) and propylene glycol monolaurate (PGML). The amounts of PG, DiPG and TC that were taken up by, and that penetrated the skin were also measured, with a clear dependence of ANT penetration on the rate and extent of PG and TC permeation. The present work investigates ANT skin delivery from a range of binary and ternary systems to determine any potential improvement in skin uptake compared with earlier results for the neat solvents. Following miscibility and stability studies a total of eight formulations were taken forward for evaluation in human skin in vitro. Binary systems of PG and water did not result in any skin permeation of ANT. Combining PG with either PGMC or PGML did promote skin penetration of ANT but no significant improvement was evident compared with PG alone. More complex ternary systems based on PG, DiPG, PGMC, PGML and water also did not show significant improvements on ANT permeation, compared with single solvents. Total skin penetration and retention of ANT ranged from 1 to 6% across all formulations studied. Where ANT was delivered to the receptor phase there were also high amounts of PG permeation with >50% and ~35% PG present for the binary systems and ternary vehicles, respectively. These findings along with our previous paper confirm PG as a suitable solvent / SPE for ANT either alone or in combination with PGML or PGMC. The results also underline the necessity for empirical testing to determine whether or not a vehicle is acting as a SPE for a specific active in a topical formulation.

Abstract  In this study, we examined the influence of the dispersion solvent in three dipropylene-glycol/water (DPG/water) mixtures, with DPG contents of 0, 50, and 100 wt%, on ionomer morphology and distribution, using dynamic light scattering (DLS) and molecular-dynamics (MD) simulation techniques. The DLS results reveal that Nafion-ionomer aggregation increases with decreasing DPG content of the solvent. Increasing the proportion of water in the solvent also led to a gradual decrease in the radius of gyration (Rg) of the Nafion ionomer due to its strong backbone hydrophobicity. Correspondingly, MD simulations predict Nafion-ionomer solvation energies of -147 ± 9 kcal/mol in water, -216 ± 21 kcal/mol in the DPG/water mixture, and -444 ± 9 kcal/mol in DPG. These results suggest that higher water contents in mixed DPG/water solvents result in increased Nafion-ionomer aggregation and the subsequent deterioration of its uniform dispersion in the solvent. Moreover, radial distribution functions (RDFs) reveal that the (-CF2CF2-) backbones of the Nafion ionomer are primarily enclosed by DPG molecules, whereas the sulfonate groups (SO3-) of its side chains mostly interact with water molecules.

Abstract  Anthramycin (ANT) was the first pyrrolobenzodiazepine (PBD) molecule to be isolated, and is a potent cytotoxic agent. Although the PBD family has been investigated for use in systemic chemotherapy, their application in the management of actinic keratoses (AK) or skin cancer has not been investigated to date. In the present work, anthramycin (ANT) was selected as a model PBD compound, and the skin penetration of the molecule was investigated using conventional Franz diffusion cells. Finite dose permeation studies of ANT were performed using propylene glycol (PG), 1,3-butanediol (BD), dipropylene glycol (DiPG), Transcutol P® (TC), propylene glycol monocaprylate (PGMC), propylene glycol monolaurate (PGML) and isopropyl myristate (IPM). The skin penetration of BD, DiPG, PG and TC was also measured. Penetration of ANT through human skin was evident for TC, PG and PGML with the active appearing to "track" the permeation of the vehicle in the case of TC and PG. Deposition of ANT in skin could be correlated with skin retention of the vehicle in the case of IPM, PGMC and PGML. These preliminary findings confirm the ability of ANT to penetrate human skin and, given the potency of the molecule, suggest that further investigation is justified. Additionally, the findings emphasise the critical importance of understanding the fate of the excipient for the rational design of topical formulations.

Abstract  The first objective of the proposed research work includes comparative bioavailability and bioequivalence evaluation of oxybutynin transdermal patch with respect to different permeation enhancers. The second objective was to evaluate different in vitro methods along with synthetic membranes toward development of an in vitro-in vivo correlation. Oleic acid (fatty acid), Soluphor P (2-pyrrolidone, cosolvent), menthol (volatile oil), and dipropylene glycol (plasticizer) were selected as representatives from different classes of permeation enhancers. A random, crossover, single-dose pharmacokinetic study was carried out on male New Zealand white rabbits to determine bioavailability and bioequivalence. The obtained pharmacokinetic data were correlated with in vitro drug release using convolution-deconvolution approach. All developed formulations were found to be bioequivalent with respect to the marketed patch (Oxytrol®) on the basis of level of C max, AUC0-96, and AUCtotal (0.8-1.25). A biphasic linear correlation was obtained pertaining to differential diffusion behavior of the drug in vivo during the experimental timeframe. Because of close resemblance to skin, Cuprophan® membrane was found to be more suitable for developing an IVIVC than Millipore® membrane.

Abstract  Dielectric relaxation spectra of two closely related glass formers, dipropylene glycol [H-(C3H6O)2-OH] and dipropylene glycol dimethyl ether [CH3-O-(C3H6O)2-CH3], were measured at ambient and elevated pressures in the supercooled and the glassy states are presented. Hydrogen bonds formed in dipropylene glycol are removed when its ends are replaced by two methyl groups to become dipropylene glycol dimethyl ether. In the process, the primary relaxation, the excess wing, and the resolved secondary relaxation of dipropylene glycol are all modified when the structure is transformed to become dipropylene glycol dimethyl ether. The modifications include the pressure and temperature dependences of these relaxation processes and their interrelations. Thus, by comparing the dielectric spectra of these two closely related glass formers at ambient and elevated pressures, the differences in the relaxation dynamics and properties in the presence and absence of hydrogen bonding are identified.

Abstract  Ferulic acid (F.A) receives significant interest in the beauty industry with regard to its skin-whitening and anti-oxidant properties. However, its use in cosmetics is limited due to pH- and temperature-related instabilities. In this study, we investigated the stability of F.A in eight different prototype formulae. The results confirmed that in our conditions the stability of F.A is pH- and temperature-related. Additionally, the nature of the solvent dipropylene glycol (DPPG) showed a capacity to stabilize F.A. A series of experiments was further planned for studying the mechanism of degradation of F.A. In a prototype of a cosmetic medium, F.A degrades first through a decarboxylation step, leading to 4-hydroxy-3-methoxystyrene (PVG). Further, F.A and PVG are both involved in an additional reaction, resulting in the trans-conjugation dimer of PVG. The consequences of these results in formulating F.A are discussed.

Abstract  Propylene carbonate and a mixture of two secondary amides, N-methylformamide and N-ethylacetamide, are investigated by means of broadband dielectric and mechanical shear spectroscopy. The similarities between the rheological and the dielectric responses of these liquids and of the previously investigated tripropylene glycol are discussed within a simple approach that employs an electrical circuit for describing the frequency-dependent behavior of viscous materials. The circuit is equivalent to the Gemant-DiMarzio-Bishop model, but allows for a negative capacitive element. The circuit can be used to calculate the dielectric from the mechanical response and vice versa. Using a single parameter for a given system, good agreement between model calculations and experimental data is achieved for the entire relaxation spectra, including secondary relaxations and the Debye-like dielectric peak in the secondary amides. In addition, the predictions of the shoving model are confirmed for the investigated liquids.

Abstract  Central dosing units for surface disinfectants can constitute a particular hygiene problem in hospitals if a biofilm can develop in the piping system despite the disinfectant solution that is present. In earlier studies it was able to be shown that oxygen-releasing compounds in particular were highly effective against microorganisms in generated biofilms. The purpose of the study presented was to investigate in a test simulating practical conditions whether, in addition to the described good effect, peroxide-containing solutions also have a uniform effect against all isolates from disinfectant use-solutions, or whether there are differences. The results show that a 1% H2O2 solution (C) was not sufficiently effective against all test organisms after a contact time of one hour. In contrast, the 1% test solution of A (10% perglutaric acid, 28% H2O2, < 0.5% perbenzoic acid) was highly and uniformly effective. The 3% test solution of B (10% tertiary butylhydroperoxide, 20% phenoxypropanols, 48% dipropylene glycol) exhibited weaknesses against some test organisms after the one-hour contact time. After a contact time of three hours, this solution, unlike the 1% H2O2 solution achieved a reduction in bacterial count of more than 5 log steps against all species. On the basis of these results, before cleaning piping systems it appears advisable to test the effectiveness of the solution to be used in a suitable test with the isolates.