A simple instrument-free gaseous chlorine dioxide method for microbial decontamination of potatoes during storage

An instrument-free gaseous chlorine dioxide (ClO₂) method to control microorganisms on potatoes during storage was developed. Gaseous ClO₂ was generated by combining an equal amount of impregnated sodium chlorite and activating acids in a sachet without using any solution or equipment. After activation by mixing, the sachet was placed in the application area. The decontamination efficiency of ClO₂ on natural microbiota including total microorganisms, yeasts and molds, and inoculated Pseudomonas aeruginosa on potatoes was investigated. Different treatments using 2, 3, and 4 g of materials and various time intervals (2.5 and 5 h) to generate 16, 20, 24, 30, 32, and 40 mg/L of ClO₂ were evaluated. The results were effective for natural microbiota, showing over a 5 log CFU/potato reduction with a 4 g treatment after 5 h. For P. aeruginosa, there was almost a 6 log CFU/potato reduction after 5 h of the 4 g treatment. The lowest treatment tested (2 g at 2.5 h) showed reductions of 1.7, 1.9, and 2.3 log CFU/potato for total microorganisms, yeasts and molds, and P. aeruginosa, respectively. Gaseous ClO₂ did not affect the overall visual quality of the potato. The residue of ClO₂ decreased to <1 mg/L after 14 days for each treatment, indicating ClO₂ dissipates naturally over time.     

Functionalized‐Silk‐Based Active Optofluidic Devices

Silk protein from the silkworm Bombyx mori has excellent chemical and mechanical stability, biocompatibility, and optical properties. Additionally, when the protein is purified and reformed into materials, the biochemical functions of dopants entrained in the protein matrix are stabilized and retained. This unique combination of properties make silk a useful multifunctional material platform for the development of sensor devices. An approach to increase the functions of silk‐based devices through chemical modifications to demonstrate an active optofluidic device to sense pH is presented. Silk protein is chemically modified with 4‐aminobenzoic acid to add spectral‐color‐responsive pH sensitivity. The functionalized silk is combined with the elastomer poly(dimethyl siloxane) in a single microfluidic device. The microfluidic device allows spatial and temporal control of the delivery of analytic solutions to the system to provide the optical response of the optofluidic device. The modified silk is stable and spectrally responsive over a wide pH range from alkaline to acidic.     

Ripple induced changes in the wavefunction of graphene: an example of a fundamental symmetry breaking

Ideally, graphene may be regarded as a strictly 2-D structure. However, as it exists in a 3-D world, perturbations often distort this ideal 2-D structure. Under a variety of conditions graphene has been shown to develop ripples, which may have undesirable consequences for a variety of properties of graphene, such as electron transport. In addition to this, it has been speculated that ripples may be an intrinsic property of graphene, and it has also been suggested that unlocking the secrets of these ripples could be useful in the search for (an understanding of) the elusive Higgs boson. However, ripples in graphene can only be avoided, or utilized, if they can be reproducibly detected. Here we explore the most fundamental aspect of these ripples, that is, the effect of a static ripple structure on various properties of large graphene nanoflakes. We find that the mechanical, thermodynamic and electronic properties are unaltered by this fundamental rippling, but this spontaneous symmetry breaking induces a significant change in the structure of the wavefunction. This profound effect occurs only at the most basic level, but it should be, in principle, experimentally observable.     

The road user behaviour of school students in Belgium

The present study aimed to investigate both the on road behaviour of Belgian school students and the validity of the Adolescent Road User Behaviour Questionnaire (ARBQ) in a sample of students attending school in Belgium. In total, 294 adolescents completed the ARBQ along with measures of their self-reported accident involvement and sensation seeking behaviour. Confirmatory Factor Analysis supported the original factor structure of: “unsafe road crossing”, “playing on the road” and “planned protective behaviour” for the 21-item version of the questionnaire, but not for the full scale. Males were found to engage more often in unsafe crossing behaviour and playing on the roads. There were also age differences, with unsafe road crossing increasing with age and engagement in planned protective behaviours improving with age. Those who reported being involved in an accident also reported more frequent engagement in unsafe crossing, playing on the roads, thrill seeking behaviour and lower levels of behaviour inhibition. Therefore, this study confirms that the ARBQ is a useful tool for investigating safety-related behaviours that contribute to accident involvement.     

Differential effect of three base modifications on DNA thermostability revealed by high resolution melting

High resolution melting (HRM) can detect and quantify the presence of 5-methylcytosine (5mC) in DNA samples, but the ability of HRM to diagnose other DNA modifications remains unexplored. The DNA bases N6-methyladenine and 5-hydroxymethylcytosine occur across almost all phyla. While their function remains controversial, their presence perturbs DNA structure. Such modifications could affect gene regulation, chromatin condensation and DNA packaging. Here, we reveal that DNA containing N6-methyladenine or 5-hydroxymethylcytosine exhibits reduced thermal stability compared to cytosine-methylated DNA. These thermostability changes are sufficiently divergent to allow detection and quantification by HRM analysis. Thus, we report that HRM distinguishes between sequence-identical DNA differing only in the modification type of one base. This approach is also able to distinguish between two DNA fragments carrying both N6-methyladenine and 5-methylcytosine but differing only in the distance separating the modified bases. This finding provides scope for the development of new methods to characterize DNA chemically and to allow for low cost screening of mutant populations of genes involved in base modification. More fundamentally, contrast between the thermostabilizing effects of 5mC on dsDNA compared with the destabilizing effects of N6-methyladenine (m6A) and 5-hydroxymethylcytosine (5hmC) raises the intriguing possibility of an antagonistic relationship between modification types with functional significance.     

Blocking in the Morris swimming pool.

Four experiments demonstrate that spatial blocking is governed by the same principles that govern blocking in Pavlovian conditioning. In the 2nd stage of each experiment, rats escaped from a Morris swimming pool by swimming to a submerged platform with a beacon attached to it. Test trials were then conducted in the absence of the platform and the beacon to assess the extent to which subjects had learned about the position of the platform with reference to the room cues. For the 1st stage of their training, rats either swam to the platform and beacon in the presence of curtains that prevented the room cues from being seen (Experiments 1 & 2), or they swam to the platform and beacon that were moved from trial to trial (Experiments 3 & 4). In each experiment, learning about the room cues in the 2nd stage of the experiment was blocked by the presence of the beacon. This blocking effect was disrupted by changing the appearance of the beacon for the 2nd stage of training or by restricting the amount of exposure to the beacon during the 1st phase of training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of landscape metrics for conservation planning

This study examined the extent to which commonly used and easily obtained landscape metrics contribute to a conservation planning process that must be completed rapidly and economically. Specifically, we aimed to determine if landscape metrics could be used to guide the prioritization process when the importance of sites to conservation portfolios is measured in terms of irreplaceability, as measured by the probability that a particular site will be required in conservation reserve network. This question was examined in the context of a flexible planning process where the size of a conservation portfolio may vary over time. We used avian survey data from 35 riparian forest sites in central Ohio to calculate irreplaceability scores for each site. Landscape composition within a 1-km radius of each site was measured as the number of buildings and the percent forest, agriculture, roads, pavement and mowed surfaces. Multinomial logistic regression models were created and compared using Akaike Information Criterion. Results suggest that when predicting the irreplaceability value of a site, a simple yet effective method involves the use of forest coverage at the landscape-level plus one metric measuring human disturbance. This result appears to hold across a range of portfolio sizes and is therefore useful even in the context of a planning process that varies in scope over time.