Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas

A nationally consistent approach was used to assess the occurrence and potential sources of pyrethroid insecticides in stream bed sediments from seven metropolitan areas across the United States. One or more pyrethroids were detected in almost half of the samples, with bifenthrin detected the most frequently (41%) and in each metropolitan area. Cyhalothrin, cypermethrin, permethrin, and resmethrin were detected much less frequently. Pyrethroid concentrations and Hyalella azteca mortality in 28-d tests were lower than in most urban stream studies. Log-transformed total pyrethroid toxic units (TUs) were significantly correlated with survival and bifenthrin was likely responsible for the majority of the observed toxicity. Sampling sites spanned a wide range of urbanization and log-transformed total pyrethroid concentrations were significantly correlated with urban land use. Dallas/Fort Worth had the highest pyrethroid detection frequency (89%), the greatest number of pyrethroids (4), and some of the highest concentrations. Salt Lake City had a similar percentage of detections but only bifenthrin was detected and at lower concentrations. The variation in pyrethroid concentrations among metropolitan areas suggests regional differences in pyrethroid use and transport processes. This study shows that pyrethroids commonly occur in urban stream sediments and may be contributing to sediment toxicity across the country.     

Impact of storage time and temperature on thermal inactivation of Salmonella Enteritidis PT 30 on oil-roasted almonds

Whole Nonpareil variety almonds were inoculated with Salmonella Enteritidis PT 30 and stored at 4 or 23 °C for up to 48 wk. At 1, 12, 24, 37, and 48 wk of storage, almonds were heated by immersion in 121 °C oil. After heating for 0.5 to 2.5 min, almonds were drained, transferred to tryptic soy broth, and mixed with a stomacher prior to plating onto tryptic soy and bismuth sulfite agars. Over the 48 wk of storage, Salmonella declined by 0.5 and 2.1 log CFU/g at 4 and 23 °C, respectively. The survivor inactivation curves were upwardly concave with rapid initial reductions in the levels of Salmonella. For up to 24 wk of storage, the mean counts of the survivors after treatment were not significantly different. The Weibull model predicted 4- and 5-log reductions of Salmonella in 0.85 ± 0.16 and 1.8 ± 0.43 min, respectively, for almonds stored at 4 °C, and in 1.6 ± 0.53 and 3.2 ± 1.0 min, respectively, for almonds stored at 23 °C. Refrigerated storage had little impact on heat resistance of Salmonella that were inoculated on almonds. PRACTICAL APPLICATION: This research provides information of value in performing or evaluating validation studies for thermally processed almonds. The sensitivity of Salmonella to oil roasting is demonstrated during typical commercial almond storage times and temperatures.     

Effectiveness of chitosan on the inactivation of enteric viral surrogates

Chitosan is known to have bactericidal and antifungal activity. Although human noroviruses are the leading cause of non-bacterial gastroenteritis, information on the efficacy of chitosan against foodborne viruses is very limited. The objective of this work was to determine the effectiveness of different molecular weight chitosans against the cultivable human norovirus and enteric virus surrogates, feline calicivirus, FCV-F9, murine norovirus, MNV-1, and bacteriophages, MS2 and phiX174. Five purified chitosans (53, 222, 307, 421, ∼1150 kDa) were dissolved in water, 1% acetic acid, or aqueous HCl pH = 4.3, sterilized by membrane filtration, and mixed with equal volume of virus to obtain a final concentration of 0.7% chitosan and 5 log₁₀ PFU/ml virus. Virus-chitosan suspensions were incubated for 3 h at 37 °C. Untreated viruses in PBS, in PBS with acetic acid, and in PBS with HCl were tested as controls. Each experiment was run in duplicate and replicated at least twice. Water-soluble chitosan (53 kDa) reduced phiX174, MS2, FCV-F9 and MNV-1 titers by 0.59, 2.44, 3.36, and 0.34 log₁₀ PFU/ml respectively. Chitosans in acetic acid decreased phiX174 by 1.19–1.29, MS2 by 1.88–5.37, FCV-F9 by 2.27–2.94, and MNV-1 by 0.09–0.28 log₁₀ PFU/ml, respectively. Increasing the MW of chitosan corresponded with an increasing antiviral effect on MS2, but did not appear to play a role for the other three tested viral surrogates. Overall, chitosan treatments showed the greatest reduction for FCV-F9, and MS2 followed by phiX174, and with no significant effect on MNV-1.     

Questioning the assumptions: the role of vulnerability assessments in climate change adaptation

A number of challenges prevent climate change adaptation activities from contributing to vulnerability reduction. Some of these relate to the nature and quality of vulnerability assessments, while others concern how well assessments link with adaptation actions. By highlighting four persistent assumptions about the role of vulnerability assessments in adaptation, this paper seeks to identify ways in which the practice of vulnerability assessment can better support progressive adaptation actions. This paper argues that, for adaptation actions identified within vulnerability assessments to be successful, there is a need for assessment to: (i) engage with marginalized perspectives; (ii) draw upon diverse knowledge domains; (iii) integrate scales of analysis with appropriate scales of action; and (iv) build political will. This requires vulnerability assessment to be considered as more than just a method for information generation on who is most vulnerable to climate change, where they are located and the underlying reasons for their vulnerability. In addition, improving the rigor and transparency of assessments and engagement with stakeholders during the assessment process can better facilitate vulnerability-focused adaptation.     

A Battery-Aware Algorithm for Supporting Collaborative Applications

There are several significant ways in which the ubiquity of battery-powered devices impacts the field of collaborative computing. First, applications such as collaborative data gathering become possible. Also, existing applications that depend on collaborating devices to maintain the system infrastructure must be reconsidered. The problem is that collaborative applications often require end-user devices to perform background tasks that are not directly advantageous to the user. In this work, we seek to better understand how laptop users use their batteries and explore the cost associated with using a laptop in a common peer-to-peer network??Gnutella. Based upon our findings, we evaluate a battery-aware alternative to Gnutella??s ultrapeer selection algorithm. The most significant result of our study indicates that a large portion of laptop users can participate in system maintenance without sacrificing any of their battery. These results show great promise for existing collaborative applications as well as new applications, such as collaborative data gathering.     

A Study of the Photoyellowing of Paper Made from Bleached CTMP

The photoyellowing of papers produced from bleached CTMP is retarded when these papers are irradiated in aqueous solutions containing reducing agents such as Rongalit C and Blankit D. Papers impregnated with the reducing agents showed some photostability when irradiated in the dry state but not when irradiated in aqueous solution. The reducing agents present in these papers also failed to significantly retard the photoyellowing under natural lighting conditions and under simulated solar irradiation. It is concluded that the migratability of the reducing agents is important if photoprotection is to be achieved and that the latter is caused by the reagents bleaching the yellow photodegradation products as well as destroying prodegradent species such as hydroperoxides.     

Monitoring changes in feta cheese during brining by magnetic resonance imaging and NMR relaxometry

Magnetic resonance imaging (MRI) and NMR relaxometry were used to monitor changes in feta cheese during 169 h of brining at 4.8%, 13.0% and 23.0% salt solutions. Image and relaxation data were acquired to study salt uptake and water loss due to dehydration of cheese during brining. Saturation recovery and Carr-Purcell-Meiboom-Gill (CPMG) sequences were used to determine the longitudinal relaxation (T₁) and the transverse relaxation (T₂) times, respectively. Signal intensities of T₂ weighted images decreased during 169 h of brining. An excellent linear correlation between the average signal intensity and the water content was obtained (R² = 0.984). The T₁ values of cheese brined at 4.8% were almost constant but T₁ values decreased for both 13.0% and 23.0% salt brined cheeses. Analysis of the CPMG decays gave relaxation spectra containing two components which decreased during brining. The short component T_2a was highly correlated with salt content (R² = 0.974). Results showed that NMR and MRI can be used to follow salt uptake and changes in water content in cheese during brining.     

Vapor phase deposition of copper films with a Cu(I) β-diketiminate precursor

This work demonstrates the vapor phase deposition of copper films with a volatile Cu(I) β-diketiminate precursor. X-ray photoelectron spectroscopy (XPS) depth profiles of the deposited films show only background levels of carbon and oxygen. Film thickness depends on the length of precursor pulse, but the surface roughness does not, a result that suggests a uniform deposition. XPS data for the chemisorbed copper precursor show that the copper was in both the metallic and + 1 oxidation states. Chemisorption of the Cu(I) precursor deposited a Cu(I) species. However, disproportionation of some of the chemisorbed Cu(I) precursor generated Cu(0) and a volatile Cu(II) complex, which was removed from the surface. These results are characteristic of a pulsed chemical vapor deposition.     

Composite relation for laminar free convection in inclined channels with uniform heat flux boundaries

A composite correlation of the average Nusselt number and the channel Rayleigh number for buoyant air flow through inclined channels with uniform heat flux boundaries is presented. The form of the correlation is based on dimensional analysis and is a superposition of the developing and fully developed flow limits. In the limit of fully developed flow, an analytical solution for the Nusselt number is derived. The developing flow limit follows the format of the correlation for a single plate. The composite relationship based on the top wall temperature is $\overline{\text{Nu}}={\left[\frac{6.25(1+r)}{{\text{Ra}}^{″}\sin ?}+\frac{1.64}{({\text{Ra}}^{″}\sin ?{)}^{2/5}}\right]}^{-1/2}$, where r is ratio of the heat flux at the top and bottom wall. At inclination angles of $30°\le ?\le 90°$, this correlation predicts the available data base for $10\le {\text{Ra}}^{″}\le {10}^5$ and agrees with the analytical solution for $1\le {\text{Ra}}^{″}\le {10}^2$.