Spontaneous Exciton Dissociation at Organic Semiconductor Interfaces Facilitated by the Orientation of the Delocalized Electron–Hole Wavefunction

In organic semiconductors, optical excitation does not necessarily produce free carriers. Very often, electron and hole are bound together to form an exciton. Releasing free carriers from the exciton is essential for the functioning of photovoltaics and optoelectronic devices, but it is a bottleneck process because of the high exciton binding energy. Inefficient exciton dissociation can limit the efficiency of organic photovoltaics. Here, nanoscale features that can allow the free carrier generation to occur spontaneously despite being an energy uphill process are determined. Specifically, by comparing the dissociation dynamics of the charge transfer (CT) exciton at two donor–acceptor interfaces, it is found that the relative orientation of the electron and hole wavefunction within a CT exciton plays an important role in determining whether the CT exciton will decompose into the higher energy free electron–hole pair or relax to the lower energy tightly‐bound CT exciton. The concept of the entropic driving force is combined with the structural anisotropy of typical organic crystals to devise a framework that can describe how the orientation of the delocalized electronic wavefunction can be manipulated to favor the energy‐uphill spontaneous dissociation of CT excitons over the energy‐downhill CT exciton cooling.     

Use of spectral analysis to test hypotheses on the origin of pinnipeds

The evolutionary origin of the pinnipeds (seals, sea lions, and walruses) is still uncertain. Most authors support a hypothesis of a monophyletic origin of the pinnipeds from a caniform carnivore. A minority view suggests a diphyletic origin with true seals being related to the mustelids (otters and ferrets). The phylogenetic relationships of the walrus to other pinniped and carnivore families are also still particularly problematic. Here we examined the relative support for mono- and diphyletic hypotheses using DNA sequence data from the mitochondrial small subunit (12S) rRNA and cytochrome b genes. We first analyzed a small group of taxa representing the three pinniped families (Phocidae, Otariidae, and Odobenidae) and caniform carnivore families thought to be related to them. We inferred phylogenetic reconstructions from DNA sequence data using standard parsimony and neighbor-joining algorithms for phylogenetic inference as well as a new method called spectral analysis (Hendy and Penny) in which phylogenetic information is displayed independently of any selected tree. We identified and compensated for potential sources of error known to lead to selection of incorrect phylogenetic trees. These include sampling error, unequal evolutionary rates on lineages, unequal nucleotide composition among lineages, unequal rates of change at different sites, and inappropriate tree selection criteria. To correct for these errors, we performed additional transformations of the observed substitution patterns in the sequence data, applied more stringent structural constraints to the analyses, and included several additional taxa to help resolve long, unbranched lineages in the tree. We find that there is strong support for a monophyletic origin of the pinnipeds from within the caniform carnivores, close to the bear/raccoon/panda radiation. Evidence for a diphyletic origin was very weak and can be partially attributed to unequal nucleotide compositions among the taxa analyzed. Subsequently, there is slightly more evidence for grouping the walrus with the eared seals versus the true seals. A more conservative interpretation, however, is that the walrus is an early, but not the first, independent divergence from the common pinniped ancestor.      

Thiazolidinedione derivatives as PTP1B inhibitors with antihyperglycemic and antiobesity effects

Benzylidene-2,4-thiazolidinedione derivatives with substitutions on the phenyl ring at the ortho or para positions of the thiazolidinedione (TZD) group were synthesized as PTP1B inhibitors with IC₅₀ values in a low micromolar range. Compound 3e, the lowest, bore an IC₅₀ of 5.0 μM. In vivo efficacy of 3e as an antiobesity and hypoglycemic agent was evaluated in a mouse model system. Significant improvement of glucose tolerance was observed. This compound also significantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol and NEFA. Compound 3e was also found to activate peroxisome proliferator-activated receptors (PPARs) indicating multiple mechanisms of action.     

Sludge exchange process on two serial CSTRs anaerobic digestions: process failure and recovery

The sludge exchange process using two anaerobic digesters (CSTRs) in series was investigated under the mesophilic condition (36-38 °C). At first, the digesting sludge of the CSTRs in series with different TVFA/alkalinity ratios was tested in the laboratory by mixing the digesting sludge of two CSTRs from 6.5% to 50% based on volume. The sludge exchange test was then performed using the same CSTRs under batch and continuous processes. The change in the TVFA/alkalinity ratio was found to be linear with the digesting sludge exchange volume. The CSTR of TVFA/alkalinity ratio 1.970 recovered completely failed within 11 days for the batch process and the CSTR of TVFA/alkalinity ratio 1.514 within 3 weeks for the continuous feeding process at a sludge exchange volume of 13%. The reactor operation was stable when the TVFA/alkalinity ratio was less than 1.0 and when the TVFA concentration was lower than 10,000 mg L⁻¹.     

Interspecific competition between Solenopsis invicta and two native ant species, Pheidole fervens and Monomorium chinense

This study was designed to understand the effects of the interspecific competition between red imported fire ant, Solenopsis invicta Buren and two native ant species, Pheidole fervens Smith and Monomorium chinense Santschi, by conducting colony interference and individual confrontation tests under laboratory conditions. The colony interference test showed that both native ant species, owing to their numerical advantage, killed the Solenopsis invicta virus-1 (SINV-1)-infected or healthy queens of S. invicta. Significantly less time was required for M. chinense to kill all SINV-1-infected S. invicta compared with the time required to kill the healthy S. invicta. Compared with healthy S. invicta, SINV-1-infected S. invicta spent a longer time eliminating the P. fervens colonies. In confrontation tests, M. chinense killed a significantly higher number of infected S. invicta minors than they did healthy minors, but the number of S. invicta majors (either infected or healthy) killed was substantially less. This study found that the viral infection weakened the competitive ability of S. invicta and made them prone to be eliminated by M. chinense but not by P. fervens.     

Colored bait preferences of house Fly (Musca domestica L.) (Dipetera: Muscidae)

The housefly, Musca domestica L. (Dipetera: Muscidae) transmits disease, contaminates laboratories, hospitals, equipment and can be annoying to people and animals. They are considered a serious urban pest worldwide. An important tool used to control houseflies is baiting. This study was undertaken to review the preference of housefly for different colored baits. Various colored baits were prepared and evaluated under laboratory conditions. These were colored blue, white, yellow, red, purple and green. Among the different colored baits used, the blue bait was preferred the most by the houseflies, followed by the white and yellow baits, and the red, purple and green baits were least attractive to the houseflies. Similarly, the blue bait was detected faster by the houseflies and was consumed significantly more than the red, purple or green baits. Also, the blue bait attracted a significantly higher number of flies than the red, purple and green baits.     

Derivatives of 1,4-bis(3-hydroxycarbonyl-4-hydroxyl)styrylbenzene as PTP1B inhibitors with hypoglycemic activity

Disalicylic acid derivatives with stilbene and bis-styrylbenzene skeleton were synthesized as PTP1B inhibitors. The most potent in this series exhibited a submicromolar IC(50) value. One of the compounds 7b was tested in an animal model for its efficacy as an anti-diabetic or an anti-obesity agent. In feeding compound 7b to diet-induced obese mice, no significant differences in weight gain and food consumption were observed between the drug-treated and the obese control mice. However, 7b significantly lowered the fasting glucose level and improved the glucose tolerance in the obesity-induced diabetic mice.     

Inhibition of IKK-β: A new development in the mechanism of the anti-obesity effects of PTP1B inhibitors SA18 and SA32

In a previous study, protein tyrosine phosphatase 1B (PTP1B) inhibitors, SA18 and SA32, exhibited anti-obesity effects in a mouse model by suppressing weight gain and improving blood parameters, including free fatty acid (FFA) levels. In a separate study, depletion of the PTP1B gene in mice suppressed weight gain without significant change in FFA levels. The discrepancy in FFA concentrations between the two studies suggested that the in vivo target of the SA compounds might not be limited to PTP1B. In this study, SA18 and SA32 were found to be potent inhibitors of IκB Kinase-β (IKK-β). In vivo relevance of the inhibitory activity was evaluated in differentiated adipocytes. Inhibition of IKK-β, in addition to inhibition of PTP1B, in mice treated with the SA compounds, could be a possible mechanism of the compound’s biological response including the resistance to diet-induced weight gain and improvement in blood parameters. As potent and cell-permeable IKK-β inhibitors, SA18 and SA32 could also be valuable in biological experiments.