CONTRA: improving the performance of dynamic investigations in natural abundance organic solids by mirror-symmetric constant-time CODEX

We present a minor but essential modification to the CODEX 1D-MAS exchange experiment. The new CONTRA method, which requires minor changes of the original sequence only, has advantages over the previously introduced S-CODEX, since it is less sensitive to artefacts caused by finite pulse lengths. The performance of this variant, including the finite pulse effect, was confirmed by SIMPSON calculations and demonstrated on a number of dynamic systems.     

Impaired neurogenesis, learning and memory and low seizure threshold associated with loss of neural precursor cell survivin

Background

Survivin is a unique member of the inhibitor of apoptosis protein (IAP) family in that it exhibits antiapoptotic properties and also promotes the cell cycle and mediates mitosis as a chromosome passenger protein. Survivin is highly expressed in neural precursor cells in the brain, yet its function there has not been elucidated.

Results

To examine the role of neural precursor cell survivin, we first showed that survivin is normally expressed in periventricular neurogenic regions in the embryo, becoming restricted postnatally to proliferating and migrating NPCs in the key neurogenic sites, the subventricular zone (SVZ) and the subgranular zone (SGZ). We then used a conditional gene inactivation strategy to delete the survivin gene prenatally in those neurogenic regions. Lack of embryonic NPC survivin results in viable, fertile mice (Survivin ^Camcre ) with reduced numbers of SVZ NPCs, absent rostral migratory stream, and olfactory bulb hypoplasia. The phenotype can be partially rescued, as intracerebroventricular gene delivery of survivin during embryonic development increases olfactory bulb neurogenesis, detected postnatally. Survivin ^Camcre brains have fewer cortical inhibitory interneurons, contributing to enhanced sensitivity to seizures, and profound deficits in memory and learning.

Conclusions

The findings highlight the critical role that survivin plays during neural development, deficiencies of which dramatically impact on postnatal neural function.     

On the necessity of alternative approaches towards finite elastoplasticity

In order to simulate elastoplasticity within metal forming processes different approaches towards numerical implementation have been realized. Nevertheless, most of them or consider only the quasistatic case or use distinct time discretization schemes for the balance and the evolution equations. In the following, the effects of latter will be outlined on the basis of a numerical example exploiting a conventional ansatz towards finite elastoplasticity. This access should serve as a motivation for identifying why it is still important to investigate the implementation of elastoplastic phenomena beyond the well established methods. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation of slow dynamic processes in natural abundance polymeric systems by novel 1D-MAS exchange NMR methods

We introduce a recently developed class of SolidState NMR experiments for the investigation of slow dynamic processes in organic solids. These 1D-MAS exchange experiments do not require selective isotopic labeling and can be performed with standard solid-state NMR hardware. The data are easy to analyze and provide selective information about the correlation times as well as about the topology (jump angles etc.) of dynamic processes in different sub-units of the molecules. We present data for Poly(n-butylmethacrylate), PBMA, between the glass transition temperature T_g and the αβ splitting temperature, in order to demonstrate the advantages of these 1D-MAS methods.     

ChemInform Abstract: Experimental Evidence for the Existence of Neutral P6: A New Allotrope of Phosphorus.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

An improved self‐assembly gold colloid film as surface‐enhanced Raman substrate for detection of trace‐level polycyclic aromatic hydrocarbons in aqueous solution

To detect trace‐level polycyclic aromatic hydrocarbons, some investigations of an improved self‐assembly method are carried out using gold colloid films for the preparation of the surface‐enhanced Raman scattering (SERS)‐active substrate. Extinction spectra and scanning electron microscopy images reveal that controllable surface plasmonic metal substrates can be obtained by increasing the temperature of (3‐aminopropyl)trimethoxysilane solution up to 64.5 °C. The SERS‐active substrates have a high enhancement factor, and they can be both easily prepared and reproducible. With the use of these substrates, different concentrations of pyrene and anthracene in aqueous solutions were detected by SERS. A further enhancement can be supported by shifted excitation Raman difference spectroscopy. Raman signals of pyrene and anthracene adsorbed on gold colloid substrates up to limits of detection at 5 and 1 nmol/l, respectively, can be obtained. The quantitative analysis shows the possibility of in situ detection of polycyclic aromatic hydrocarbons while such gold colloid film serves as a SERS‐active substrate. Copyright © 2012 John Wiley & Sons, Ltd.     

ChemInform Abstract: Towards Detection of a Long‐Lived Protonated Metal Cation: Generation of GeH2+ Using High‐Energy Collisions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

ChemInform Abstract: Structure of the SO2F‐ Anion,a Problem Case.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Realstrukturuntersuchungen von hydrothermal auf kleinen Rhomboederflächen gewachsenen Quarzeinkristallen

Crystals of α-quartz, which were grown from seeds of the minor rhombohedral face (1 011) and the basal face (0001), were examined with optical, etching and x-ray topographic methods. In agreement with the literature we have observed that there is a heavier coloration due to Al-impurity after x-ray irradiation, in the (1 011)-growth direction, than in others; the basal growth sector remains colourless. The strong coloration must not be in agreement with a high dislocation density. The dislocations in the rhombohedral growth are characteristically different from that of the basal growth. Correlation of the observed surface structure, as hillocks, terraces, and spirals with the distribution of etch pits is not observable.