Synthesis and reactivity of stable trisyl(aminomethylphenyl)silylenoid

A highly thermally stable silylenoid, trisyl(aminomethylphenyl)silylenoid (2) was synthesized from the reaction of dimethylaminomethylphenyllithium with a bromosilylenoid, 1. Silylenoid 2 reacted with electrophiles to give the corresponding products, but did not react with alkyllithiums as a nucleophile.     

Bioaccumulation of antimony, arsenic, and mercury in the vicinities of a large antimony mine, China

To study the characteristics of antimony (Sb) bioaccumulation under high Sb background values, aquatic, amphibious and terrestrial biological samples were collected in the vicinity of the Xikuangshan (XKS) Sb mine area in China. Hydride generation-atomic fluorescence (HG-AFS) analysis showed that Sb concentrations in terrestrial invertebrates (average 30,400 μg kg^− 1 dry wt.) were higher than those in aquatic (average 5200 μg kg^− 1 dry wt.) and amphibian (average 2300 μg kg^− 1 dry wt.) biological samples. Within 1 km distance of the XKS Sb mine area, grasshoppers (Acrida chinensis) and earthworms (Pheretima aspergillum) had the highest Sb amounts of 17,300 ±3200 and 43,600 ± 47,700 μg kg^− 1 dry wt., respectively. No Sb biomagnifications were observed. The bioavailability of Sb was found to be lower than those of As and Hg. A preliminary conclusion is that antagonistic effects exist between Sb and Hg accumulation in biological samples from aquatic environments. Our study is the first to report such antagonistic effects between Sb and Hg. If this deduction proves to be correct, it should be taken into consideration in assessing human health risks, especially when Sb and Hg concentrations in the aquatic environments are high.     

The effect of volatile organic compounds and hypoxia on paper degradation

The possible effects of volatile organic compounds (VOCs) and of hypoxic conditions on the durability of library and archival collections have been investigated. There is growing evidence that particularly in micro-environments, there may be an important contribution of these indoor-generated pollutants to the degradation of paper. However, since the principal source of VOCs in repositories is the collections themselves, there are also significant possibilities for less stable papers, which are net VOC emitters, to promote the degradation of more stable papers, which may be net VOC absorbers.Using a range of model and real historic papers, the influence of acetic acid, formic acid, furfural, toluene, 1,4-diethylbenzene, iso-butylbenzol, 2-pentylfuran, paraformaldehyde, hexanal and vanillin was evaluated by adding them to samples degraded in closed vessels at elevated temperature. Possible protective effects of the use of activated charcoal cloth, oxygen removal, and of various chemisorbents were also investigated.The results strongly suggest that particularly VOCs with acidic or oxidisable functions can have a strong effect on degradation of cellulose. This is less pronounced in lignin-containing and acidic papers and more pronounced in papers with a small alkaline reserve. The removal of VOCs from the immediate environment can have a pronounced beneficial effect on papers emitting VOCs more intensively, in fact, the lifetime expectancy can be doubled.The results have immediate implications for storage of paper-based heritage in enclosures, but also for initiation of long-term VOC monitoring programmes in libraries and archives, where significant development is still needed.     

Electrophoretic detection of genetic variability among Schistosoma japonicum isolates by sequence-related amplified polymorphism

In the present study, sequence‐related amplification polymorphism (SRAP) was utilized to study the genetic variability among Schistosoma japonicum isolates from different provinces in China, using Schistosoma mansoni from Puerto Rico for comparison. Five out of ten tested SRAP primer combinations displayed significant polymorphisms among S. japonicum isolates from China, namely ME2/EM1, ME4/EM1, ME4/EM6, ME5/EM4 and ME5/EM5. Analysis of the 61 S. japonicum samples from China with five SRAP primer combinations identified a total of 83 reproducible polymorphic fragments. The number of fragments using each primer combination ranged from 14 to 19, with an average of 16 polymorphic bands per primer pair, and the size of fragment ranged approximately from 100 to 1000 bp. Representative‐specific SRAP fragments were excised from the gels, and confirmed by PCR amplification of genomic DNA using primers designed and based on the sequences of these SRAP fragments. Based on SRAP profiles, unweighted pair‐group method with arithmetic averages (UPGMA) dendrogram was constructed. UPGMA clustering algorithm categorized S. japonicum isolates from China into nine clades and two lineages (representing the mountainous and lake/marshland regions). These results indicate the usefulness of the SRAP technique for revealing genetic variability among S. japonicum isolates from China, and the SRAP technique should be applicable to other living organisms.     

Energy decomposition analysis based on a block-localized wavefunction and multistate density functional theory

An interaction energy decomposition analysis method based on the block-localized wavefunction (BLW-ED) approach is described. The first main feature of the BLW-ED method is that it combines concepts of valence bond and molecular orbital theories such that the intermediate and physically intuitive electron-localized states are variationally optimized by self-consistent field calculations. Furthermore, the block-localization scheme can be used both in wave function theory and in density functional theory, providing a useful tool to gain insights on intermolecular interactions that would otherwise be difficult to obtain using the delocalized Kohn-Sham DFT. These features allow broad applications of the BLW method to energy decomposition (BLW-ED) analysis for intermolecular interactions. In this perspective, we outline theoretical aspects of the BLW-ED method, and illustrate its applications in hydrogen-bonding and π-cation intermolecular interactions as well as metal-carbonyl complexes. Future prospects on the development of a multistate density functional theory (MSDFT) are presented, making use of block-localized electronic states as the basis configurations.     

How do electron localization functions describe π-electron delocalization?

Scalar fields provide an intuitive picture of chemical bonding. In particular, the electron localization function (ELF) has proven to be highly valuable in interpreting a broad range of bonding patterns. The discrimination between enhanced or reduced electron (de)localization within cyclic π-conjugated systems remains, however, challenging for ELF. In order to clearly distinguish between the local properties of ten highly and weakly π-(de)localized prototype systems, we compare the ELFs of both the canonical wave functions and electron-localized states (diabatic) with those of two closely related scalar fields: the electron localizability indicator (ELI-D) and the localized orbital locator (LOL). The simplest LOL function distinguishes enhanced from weak π-(de)localization in an insightful and reliable manner. LOL offers the finest contrast between annulenes with 4n/4n + 2 π electrons and their inorganic analogues as well as between hyperconjugated cyclopentadiene derivatives. LOL(π) also gives an appealing and intuitive picture of the π-bond. In contrast, the most popular ELF fails to capture subtle contrasting local electronic properties and suffers from the arbitrariness of the σ/π dissection. The orbital separation of the most recent ELI-D is clear-cut but the interpretations sometime less straightforward in the present context.     

Self-assembly of a peptide amphiphile based on hydrolysed Bombyx mori silk fibroin

An octapeptide, GAGAGAGY, was obtained by a novel method, i.e. hydrolysing Bombyx mori silk fibroin. Afterward, a dodecanoic acid-peptide conjugation was synthesized. This amphiphile assembled into cylindrical nanofibers of planar β-sheets at pH 9 and twisted β-sheets at pH 4.     

Development of target-specific multimodality imaging agent by using hollow manganese oxide nanoparticles as a platform

A platform protocol developed based on the hollow manganese oxide nanoparticles provided multimodal diagnostic agents, which allow the selectively detect vulva cancer with T(1)-weighted in vivo MRI.     

Comparative photophysical properties between bicyclo[2.2.2]octadiene (BCOD)- and benzo-fused free-base triphyrins (2.1.1)

We have investigated the photophysical properties of two types of triphyrins with focus on the fused-moiety effects by performing various spectroscopic measurements and theoretical calculations.     

Synthesis of Pt@Fe2O3 nanorods as MRI probes for in vivo application

Magnetic Fe(2)O(3) nanorods with low cell toxicity were successfully synthesized via a wet-chemical method. In vivo studies with a rabbit model show that the nanorods exhibit excellent T(2) signal enhancement. This work demonstrates that magnetic nanorods may provide a new type of MR enhancement agent for use in biomedical applications.