Behavior of female Rhyzopertha dominica (Coleoptera: Bostrichidae) in a mono-layer of wheat treated with diatomaceous earth

Adult female lesser grain borers (Rhyzopertha dominica [F.]) were observed in a mono-layer of wheat sandwiched between two layers of glass to determine if movement patterns and survival rates differed in wheat that was admixed with diatomaceous earth (DE) compared with untreated wheat. Observations were also made to determine if responses to DE differed depending on the commercial formulation of DE tested at the labeled rates. Mortality was higher in the DE treatments than in the untreated controls, and also varied according to the DE formulation. In wheat treated with 1000 ppm Dryacide^®, 400 ppm Protect-It^®, and 500 ppm Insecto™ (labeled rate for the individual products), mean percentage mortality was 100±0, 71.4±10.1, and 57.1±11.1, respectively. Although total distance traveled and the number of turns taken by the beetles was lower in the Dryacide treatment compared to the untreated controls, the movement patterns were not significantly different among the three DE treatments. Observed differences in mortality are likely related to DE products or amount applied rather than to differences in DE exposure resulting from movement behavior.     

Effects of electrical brain stimulation on brain indices and presence experience in immersive,interactive virtual reality

Virtual Reality - The subjective presence experience in virtual reality (VR) is associated with distinct brain activation patterns. Particularly, the dorsolateral prefrontal cortex (DLPFC) seems to...     

S-methyl derivatives from thiol compounds by the pyrolytic reaction with trimethylsulfonium hydroxide

Base-catalyzed transesterification of acyl lipids with methanol in the presence of trimethylsulfonium hydroxide (TMSH) is an easy and convenient method for the preparation of fatty acid methyl esters for gas chromatography (GC) analyses. Free fatty acids are converted to fatty acid methyl esters by the pyrolytic reaction with TMSH as well. We have found that lipids and other compounds containing thiol groups are also converted easily to the corresponding methyl sulfides (methyl thioethers) by the pyrolytic reaction with TMSH occurring in the injector of the gas chromatograph. For example, alkane thiols such as dodecane thiol and octadecane thiol are converted to the corresponding alkyl methyl sulfides, whereas bis(methylthio) derivatives are formed from α,ω-alkane dithiols, e.g., 1,8-octanedithiol, and from 2,3-dimercaptopropan-1-ol (dimercaprol). Furthermore, 3β-mercaptocholest-5-ene (thiocholesterol) is converted to 3-methylthiocholest-5-ene by the same reaction. The S-methylation reactions which finally lead to the corresponding methylthio derivatives of lipids and other compounds with thiol groups may be of diagnostic value for the structural analysis of such compounds by GC and GC/mass spectrometry.     

Comparison of unitary transforms using Franson interferometry

Unknown unitary transforms may be compared to each other in a way which makes it possible to obtain an unambiguous answer, indicating that the transforms are different, already after a single application of each transform. Quantum comparison strategies may be useful for example if we want to test the performance of individual gates in a quantum information or quantum computing network. It is then possible to check for errors by comparing the elements to a master copy of the gate, instead of performing a complete tomography of the gate. In this paper we propose a versatile linear optical implementation based on the Franson interferometer with short and long arms. A click in the wrong output port unambiguously determines that the tested gate is faulty. This set-up can also be used for a variety of other tasks, such as confirming that the two transforms do not commute or do not anticommute.     

Amino-Acid-Anthraquinone Click Chemistry Conjugates Selectively Target Human Telomeric G-Quadruplexes

Guanine-rich sequences are known to fold into G-quadruplex (G4) arrangements, which are present in oncogenes and in the telomeric regions of chromosomes. In particular, G4s represent an obstacle to functioning of telomerase, an enzyme overexpressed in cancer cells causing their immortalization. Therefore, G4 stabilization using small molecules represents an appealing strategy for the medicinal chemist. Ligands based on an anthraquinone scaffold, to which peptidic side chains were attached by an amide bond, were previously reported. We envisioned improving this ligand concept leveraging the click chemistry approach, which, besides representing a flexible, high yielding synthetic strategy, allows an elongation of the side chains and an increase of π–π stacking and H-bond interactions with the nucleobases through the triazole ring. Compounds were tested for their ability to interact with G4 DNA with a multiple analytical approach, demonstrating an elevated aptitude to stabilize the G4 and high selectivity over double stranded DNA.     

Reaction of Ozone with Ag(I)—Mechanistic Considerations

Ozone reacts slowly with Ag⁺ (circumneutral pH, k = (11 ± 3) × 10^?2 M^?1 s^?1). After some time, ozone decay kinetics may suddenly become faster with the concomitant formation of silver sol. As primary process, an O-transfer from O₃ to Ag(I) is suggested, whereby Ag(III) is formed [Ag⁺ + O₃ + 2 H₂O → Ag(OH)₃ + O₂ + H⁺]. This conproportionates with Ag(I), which is in large excess, leading to Ag(II) [Ag⁺ + Ag(OH)₃ ? 2 Ag(OH)⁺ + HO^?]. Further, Ag(II) reacts with ozone in a high exergonic reaction [Ag(OH)⁺ + O₃ → Ag + 2 O₂ + H⁺], where ozone acts as a reducing agent. Thereby, a single silver atom, Ag, is formed that can be oxidized by O₂ and O₃ or can aggregate to a silver sol. Aggregation slows down the rate of oxidation. When Ag⁺ is complexed by acetate ions, ozone decay and silver sol formation are speeded up by enhancing Ag(II) formation [Ag(I)acetate + O₃ → Ag(III)acetate → Ag(II) + CO₂ + ?CH₃]. In the presence of oxalate, the formed complex reacts faster with ozone than Ag⁺, and Ag(III)oxalate decarboxylates rapidly [Ag(I)oxalate + O₃ → Ag(III)oxalate → Ag⁺ + 2 CO₂]. This enhances ozone decay but prevents silver sol formation. Quantum chemical calculations have been carried out for substantiating mechanistic suggestions.     

Hydride Transfer: A Dominating Reaction of Ozone with Tertiary Butanol and Formate Ion in Aqueous Solution

This article provides evidences that hydride transfer is an important primary step in ozone reactions of formate and tertiary butanol in aqueous media. In both systems, one argument is the fact that the free hydroxyl radical yields are relative low ((40 ± 4)% and (7 ± 0.8)% for formate and tertiary butanol, respectively). Another hint is the high exergonicity of these reactions: ΔG = –249 kJ mol^?1 for formate/ozone system and ΔG = –114 kJ mol^?1 for hydride transfer followed by a methyl shift in the reaction between tertiary butanol and ozone. In addition, the main product of tertiary butanol ozonolysis is butan-2-one [(89 ± 3)%], a compound that is formed only via hydride transfer. For the reaction of ozone with formate an activation energy of (54.6 ± 1.2) kJ mol^?1 and a pre-exponential term of (2.5 ± 1.2) × 10¹¹ were determined (in the presence of tertiary butanol as ^?OH scavenger) whereas for tertiary butanol the two activation parameters were (68.7 ± 1.9) kJ mol^?1 and (2.0 ± 1.5) × 10⁹, respectively.     

Lead in Lake Michigan and Green Bay surficial sediments

Sediment samples were collected in 1987–1990 from Green Bay and in 1994–1996 from Lake Michigan. Surficial sediments (0–1 cm) from both locations were analyzed for lead for the purpose of describing the horizontal variation of lead in 1994–1996 Lake Michigan and 1987–1990 Green Bay sediments, estimating lead fluxes to surficial sediments, and comparing results to earlier studies. With Lake Michigan concentrations ranging from below the method detection limit to 180 μg/g, the surficial sediments had mean and median lead concentrations of 70 μg/g and 64 μg/g, respectively. Lead concentrations in Green Bay surficial sediments were similar to those in Lake Michigan and ranged between the method detection limit and 160 μg/g. For the bay, mean and median concentrations were 58 and 59 μg/g, respectively. Surficial lead concentrations were highest in the Southern, Waukegan, and Grand Haven basins of Lake Michigan and in the central region of Green Bay in the vicinity of Chambers Island. For Lake Michigan and Green Bay, dated sediment cores illustrate the decline in lead concentrations during the last 30 and 10 years, respectively. Lead fluxes ranged between < 0.049 and 7.2 μg/cm²/yr for Green Bay and between 0.47 and 20 μg/cm²/yr for Lake Michigan. Lead fluxes to Lake Michigan were lower than those reported for 1972. These are the most comprehensive fluxes of lead to Lake Michigan and Green Bay surficial sediments reported to date.     

(6<Emphasis Type="Italic">R</Emphasis>, 10<Emphasis Type="Italic">R</Emphasis>)-6,10,14-Trimethylpentadecan-2-one,a Dominant and Behaviorally Active Component in Male Orchid Bee Fragrances

6,10,14-Trimethylpentadecan-2-one (Hexahydrofarnesyl acetone; HHA) previously has been found to be a major component in tibial fragrances of male orchid bees, Euglossa spp. HHA is a chiral molecule with four possible stereoisomers, (6R, 10R)-, (6R, 10S)-, (6S, 10R)-, and (6S, 10S)-6,10,14-trimethylpentadecan-2-one. In the present study, we characterized HHA extracted from Euglossa as the pure enantiomer (6R, 10R)-6,10,14-trimethylpentadecan-2-one. During bioassays in Mexico and Panama, the synthetic RR-isomer attracted males of six species of orchid bees, including three that were known to contain HHA in their tibial fragrances. Possible sources of HHA for wild bees are flowers of euglossophilous orchids and aroids. With a molecular weight of 268, HHA is the largest natural molecule known to attract male orchid bees in pure form. Its attractiveness to males suggests that low-volatility compounds have a function in male signals, e.g., serve as a “base note” in complex odor bouquets.