Validation of a Simple Spectrophotometric Method for the Measurement of Quaternary Ammonium Compound Residue Concentrations in Food Production Facility

Quaternary ammonium compound (QAC) residues can increase with each application and build up over a period of time during sanitation of food plants. Therefore, it is crucial to establish a simple but accurate method for routine measurement of QAC residues in food plants. In this study, a spectrophotometric method was validated and applied for the quantification of QAC residues on stainless steel surfaces. This method was based on the formation of a colored ion pair between the quaternary ions and Eosin-Y in the presence of Triton X-100. QAC residues were recovered from surfaces using swabs and were subsequently sonicated, and the isolated extracts were analyzed with a spectrophotometer (535 nm). The method was shown to be selective in the presence of interfering substances, and a linear relationship between the absorbance and concentration of QACs was detected in the concentration range from 0.5 to 10 mg?L^?1 (r ²?>?0.99). The limit of detection and limit of quantitation were 0.53 and 1.77 mg?L^?1, respectively. Satisfactory accuracy (93–97 %) and precision (relative standard deviation (RSD)?<?2.7 %) were obtained for the method. Assessment of the effect of swabbing protocol on the recovery, repeatability and intermediate precision of the method revealed that the mean recovery of residues was 90 %. Moreover, the percent RSD was less than 8.8 and 9.4 % for repeatability and intermediate precision, respectively. QAC residues were found to be stable on stainless steel surfaces for at least 6 days following deposition, a treatment that could be a potential risk especially in dry cleaning processes.     

Fat composition of organic and conventional retail milk in northeast England

This study of UK retail milk identified highly significant variations in fat composition. The survey, conducted over 2 yr replicating summer and winter, sampled 22 brands, 10 of which indicated organic production systems. Results corroborate earlier farm-based findings considering fat composition of milk produced under conventional and organic management. Organic milk had higher concentrations of beneficial fatty acids (FA) than conventional milk, including total polyunsaturated fatty acids (PUFA; 39.4 vs. 31.8 g/kg of total FA), conjugated linoleic acid cis-9,trans-11 (CLA9; 7.4 v 5.6 g/kg of FA), and α-linolenic acid (α-LN; 6.9 vs. 4.4 g/kg of FA). As expected, purchase season had a strong effect on fat composition: compared with milk purchased in winter, summer milk had a lower concentration of saturated fatty acids (682 vs. 725 g/kg of FA) and higher concentrations of PUFA (37.6 vs. 32.8 g/kg of FA), CLA9 (8.1 vs. 4.7 g/kg of FA), and α-LN (6.5 vs. 4.6 g/kg of FA). Differences identified between sampling years were more surprising: compared with that in yr 2, milk purchased in year 1 had higher concentrations of PUFA (37.5 vs. 32.9 g/kg of FA), α-LN (6.0 vs. 5.1 g/kg of FA), and linoleic acid (19.9 vs. 17.5 g/kg of FA) and lower concentrations of C16:0 and C14:0 (332 vs. 357 and 110 vs. 118 g/kg of FA, respectively). Strong interactions were identified between management and season as well as between season and year of the study. As in the earlier farm studies, differences in fat composition between systems were greater for summer compared with winter milk. Large between-year differences may be due to changes in weather influencing milk composition through forage availability, quality, and intake. If climate change predictions materialize, both forage and dairy management may have to adapt to maintain current milk quality. Considerable variation existed in milk fat composition between brands.     

Assembling nanoparticle coatings to improve the drug delivery performance of lipid based colloids

Lipid based colloids (e.g. emulsions and liposomes) are widely used as drug delivery systems, but often suffer from physical instabilities and non-ideal drug encapsulation and delivery performance. We review the application of engineered nanoparticle layers at the interface of lipid colloids to improve their performance as drug delivery systems. In addition we focus on the creation of novel hybrid nanomaterials from nanoparticle-lipid colloid assemblies and their drug delivery applications. Specifically, nanoparticle layers can be engineered to enhance the physical stability of submicron lipid emulsions and liposomes, satbilise encapsulated active ingredients against chemical degradation, control molecular transport and improve the dermal and oral delivery characteristics, i.e. increase absorption, bioavailability and facilitate targeted delivery. It is feasible that hybrid nanomaterials composed of nanoparticles and colloidal lipids are effective encapsulation and delivery systems for both poorly soluble drugs and biological drugs and may form the basis for the next generation of medicines. Additional pre-clinical research including specific animal model studies are required to advance the peptide/protein delivery systems, whereas the silica lipid hybrid systems have now entered human clinical trials for poorly soluble drugs.     

Exploring early public responses to geoengineering

Proposals for geoengineering the Earth's climate are prime examples of emerging or 'upstream' technologies, because many aspects of their effectiveness, cost and risks are yet to be researched, and in many cases are highly uncertain. This paper contributes to the emerging debate about the social acceptability of geoengineering technologies by presenting preliminary evidence on public responses to geoengineering from two of the very first UK studies of public perceptions and responses. The discussion draws upon two datasets: qualitative data (from an interview study conducted in 42 households in 2009), and quantitative data (from a subsequent nationwide survey (n=1822) of British public opinion). Unsurprisingly, baseline awareness of geoengineering was extremely low in both cases. The data from the survey indicate that, when briefly explained to people, carbon dioxide removal approaches were preferred to solar radiation management, while significant positive correlations were also found between concern about climate change and support for different geoengineering approaches. We discuss some of the wider considerations that are likely to shape public perceptions of geoengineering as it enters the media and public sphere, and conclude that, aside from technical considerations, public perceptions are likely to prove a key element influencing the debate over questions of the acceptability of geoengineering proposals.     

ToF-SIMS analysis of chemical heterogenities in inkjet micro-array printed drug/polymer formulations

Three different formulations comprising two drugs, felodipine and hydrochlorothiazide (HCT) and two polymers, poly(vinyl pyrolidone) (PVP) and poly(lactic-co-glycolic acid) (PLGA) were inkjet printed as micro-dot arrays and analysed on an individual micro-spot basis by time-of-flight secondary ion mass spectrometry (ToF-SIMS). For the HCT/PLGA formulation, the spots showed heterogeneity of the drug and other chemical constituents. To further investigate these heterogeneities, multivariate curve resolution was applied to the ToF-SIMS hyperspectral image datasets. This approach successfully identified distinct chemical components elucidating the HCT, PLGA, substrate material, and contaminants based on sulphur, phosphorous and sodium chloride. Spots printed using either of the drugs with PVP exhibited full substrate coverage and a uniform distribution of the active ingredient along with all other constituents within the printed spot area. This represents the preferred situation in terms of stability and controlling the release of a drug from a polymer matrix.     

Feed models for coax-driven monopole and dipole antennas

A method is presented for accurately modeling a monopole or dipole antenna fed by a coaxial line. The base of the monopole is attached to a conducting plane through which the coaxial feed line extends to the feed. The feed structures considered are easily adaptable to physically rugged forms and are simple to construct. Equivalent models for the three regions of the structure are devised and coupled integral equations for aperture fields and surface currents are formulated to enforce the boundary conditions. Three variations of the feed configuration are discussed and the reflection coefficient of the antenna feed is determined from the data obtained from the solutions of the coupled integral equations. Computed reflection coefficient values are shown to agree well with values measured on laboratory models.     

Transmission through axisymmetric, cascaded cylindrical cavities coupled by apertures - part I: structures with coaxial and circular-cylindrical cross-sections

A technique is presented for determining the field in a series of cascaded, axisymmetric cylindrical cavities excited by a /spl phi/-independent source. The constituent cavities are either coaxial or circular-cylindrical. The field in each cavity is expressed in terms of the electric field in the apertures at the interfaces where adjacent cavities join. Coupled integral equations are formulated in the frequency domain from which these aperture fields are computed. From knowledge of the aperture fields, the complete field in the cavity structure can be determined. The frequency-domain data are used to compute the time-domain field in the system of cavities. Cavities were constructed and experiments performed to corroborate the computed data.     

Spectroscopic and microscopic characterizations of color lamellae in natural pink diamonds

Nineteen natural, untreated, type IaAB pink diamonds from various localities were studied. They display microscopic (～ 1 μm thick) pink lamellae along {111} in an otherwise colorless diamond. This coloration concentrated in lamellae is commonly referred to as “graining”. The diamonds were examined using high spatial resolution spectroscopic methods and transmission electron microscopy. TEM revealed that a pink lamella consists of a cluster of paired microtwins created under stress by plastic deformation. Raman line shift and broadening associated with the twinned pink lamellae indicate the presence of residual stress. Ultraviolet–visible absorption spectra from each of the samples showed a broad absorption band centered at ～ 550 nm, the source of the pink color. Cathodoluminescence spectra of the pink lamellae are different from those of the bulk, colorless diamond matrix. Within the lamellae only, the H3 center is observed along with a less intense N3 center. In some samples, instead of the N3 center a new center with a zero phonon line at 405.5 nm is observed. This previously unreported 405.5 nm center has phonon sidebands qualitatively identical to the N3 center, and may be an N3 center modified by a specific environment. These results suggest that lattice vacancies were created during twinning resulting from plastic deformation, and that impurity centers (such as those containing nitrogen) trap some of the diffusing vacancies. Since the pink lamellae are still under residual stress, new or modified defect centers are created, e.g. H3 and N3. The color center(s) responsible for the pink color (550 nm absorption) was not identified, but likely is only present in diamonds that experienced plastic deformation. Reported annealing of plastically deformed brown diamonds, which results in a residual pink color, suggests that the pink color is stable under these high pressure, high temperature conditions. The reported observations that annealing plastically deformed brown diamonds results in a residual pink color and that the pink color does not anneal out under similar high pressure, high temperature conditions, suggests that the deformation inducing pink color occurs inside the Earth's mantle, whereas brown coloration might be induced during a more recent event such as the ascent of the diamond to the surface in a kimberlitic/lamproitic eruption.     

The Impact of Job Characteristics on Work-to-Family Facilitation: Testing a Theory and Distinguishing a Construct.

This study used objective measures of job characteristics appended to the National Survey of Midlife Development in the United States (MIDUS), self-reported job characteristics, and an individual resource characteristic (orientation toward personal growth) to test a theory of work-family facilitation. Results indicated that resource-rich jobs enable work-to-family facilitation. A higher level of work-to-family facilitation was reported by individuals in jobs with more autonomy and variety and whose jobs required greater substantive complexity and social skill. There was no support for the hypotheses that these effects would be more pronounced for individuals with higher levels of personal growth. The authors found significant differences in the strength of the associations of job characteristics with work-to-family facilitation and work-tofamily conflict, suggesting they are different constructs with distinct antecedents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)