Exploring the Interplay Between Ligand Derivatisation and Cation Type in the Assembly of Hybrid Polyoxometalate Mn‐Andersons

Herein a library of hybrid Mn‐Anderson polyoxometalates anions are presented: 1 , [(MnMo₆O₁₈)((OCH₂)₃‐C‐(CH₂)₇CHCH₂)₂]^3?; compound 2 , [(MnMo₆O₁₈)((OCH₂)₃C‐NHCH₂C₁₆H₉)₂]^3?; compound 3 , [(MnMo₆O₁₈)((OCH₂)₃C‐(CH₂)₇CHCH₂)₁((OCH₂)₃C‐NHCH₂C₁₆H₉)₁]^3?; compound 4 , [(MnMo₆O₁₈)((OCH₂)₃C‐NHC(O)CH₂CHCH₂)₂]^3? and compounds 5 – 9 , [(MnMo₆O₁₈)((OCH₂)₃C‐NHC(O)(CH₂)_xCH₃)₂]), where x = 4, 10, 12, 14, and 18 respectively. The compounds resulting from the cation exchange of the anions 1 – 9 to give TBA ( a ) and DMDOA ( b ) salts, and additionally for compounds 1 , 2 and 3 , tetraphenylphosphonium (PPh₄) ( c ) salts, are explored at the air/water interface using scanning force microscopy, showing a range of architectures including hexagonal structures, nanofibers and other supramolecular forms. Additionally the solid‐state structures for compounds 1c , 2c , 4a , 6a , 9a , are presented for the first time and these investigations demonstrate the delicate interplay between the structure of the covalently derivatised hybrid organo‐clusters as well as the ion‐exchange cation types.     

Visualizing and comparing four facets of scholarly communication: producers, artifacts, concepts, and gatekeepers

This paper extends Borgman’s (Communication Research 16: 583, 1989) three-facet framework (artifacts, producers, concepts) for bibliometric analyses of scholarly communication by adding a fourth gatekeepers. The four-facet framework was applied to the field of Library and Information Science to test for variations in the networks produced using operationalizations of each of these four facets independently. Fifty-eight journals from the Information Science and Library Science category in the 2008 Journal Citation Report were studied and the network proximity of these journals based on Venue-Author-Coupling (producer), journal co-citation analysis (artifact), topic analysis (concept) and interlocking editorial board membership (gatekeeper) was measured. The resulting networks were examined for potential correlation using the Quadratic Assignment Procedure. The results indicate some consensus regarding core journals, but significant differences among some networks. Holistic measures of scholarly communication that take multiple facets into account are proposed. This work is relevant in an assessment-conscious and metrics-driven age.     

A double-headed Gly-Pro-Arg-Pro ligand mimics the functions of the E domain of fibrin for promoting the end-to-end crosslinking of gamma chains by factor XIIIa

SH3 domains are protein modules that interact with proline-rich polypeptide fragments. Cbl is an adapter-like protein known to interact with several SH3 domains, including the PLCgamma1 SH3 domain and the Grb2 amino terminal SH3 domain. Here we explore whether sequences surrounding the PLCgamma1 SH3 domain core sequence (aa.796-851) can affect the binding to Cbl, a target used as a prototypical ligand. Consistent with previous reports, our results demonstrated a weak binding of Cbl to GST fusion proteins that strictly encompass the structural core of the PLCgamma1 SH3 domain but a high-avidity binding to the Grb2 amino-terminal SH3 domain. Inclusion of amino acids immediately flanking the PLCgamma1 SH3 core domain, however, substantially increased binding of Cbl to a level comparable to that of the Grb2 amino-terminal SH3 domain. The interaction of this extended PLCgamma1 SH3 domain fusion protein with Cbl was shown to depend entirely upon the interaction of the domain with a proline-rich motif in Cbl, ruling out the possibility that amino acids adjacent to the core SH3 domain of PLCgamma1 provide independent Cbl binding. These data suggest that sequences surrounding the SH3 domain of PLCgamma1 may contribute to or stabilize the association of the domain with the target protein, thus increasing its binding efficiency.     

Epidemiologic data of stroke. Data of the WHO-MONICA Project in Germany

Analyses of stroke morbidity or mortality are usually based on official statistics. A reduction in stroke mortality rates has been shown for many countries. It is not clear, however, whether this is due to declining morbidity or case fatality (or both). For this purposes population-based register data are required. Using the standardized methodology of the WHO-MONICA Project, stroke cases were also registered in Germany from 1984 to 1993 (7,435 first-ever and recurrent stroke cases). The data collection was almost restricted to East Germany. The age-specific stroke rates in males/females showed an increase from 9/11 per 100,000 population in the youngest age group (25-34) to 1,005/779 cases per year in the oldest group under study (65-74). If one tries to classify stroke types, which is not always possible in a population-based register, the best estimate for men (women) would be: 63(62%) thromboembolic stroke, 25(22)% intracerebral hemorrhage, and 12(17)% subarachnoid hemorrhage. The 28-day case fatality of the 25-74 year old stroke patients was found to be about 40%. Neither for stroke attacks nor for case fatality was a convincing time trend over the 10-year period found. The very small changes observed over 10 years time should lead to increased attention to strokes, particularly primary and secondary prevention, and this not only in East Germany. This applies also for treatment in the acute phase, because the case fatality before admission in the hospital and during the first few days is still very high. Population-based studies of the long-term prognosis of stroke patients in Germany are also missing, i.e., including the effectiveness of various forms of treatment and rehabilitation. Systematic monitoring of the development in this field is an important part of the assessment of the quality and effectiveness of the health care service.     

Effect of thickness on the thermoelectric properties of PbS thin films

A non-monotonic dependence of the thermoelectric properties of PbS epitaxial films grown on (001)KCl substrates and covered with an EuS protective layer on the PbS layer thickness (d=2-200 nm) was detected at room temperature. The complex character of the dependence on d is attributed to a competition between percolation phenomena and size quantization. Within the framework of percolation theory on the basis of experimental data, the critical exponent for the electrical conductivity was determined. Oscillations in the thickness dependence of the kinetic coefficients are attributed to quantum size effects occurring in thin layers.     

Opioid peptide receptor studies. 9. Identification of a novel non-mu- non-delta-like opioid peptide binding site in rat brain

Quantitative binding studies resolved two high-affinity [3H][D-Ala2,D-Leu5]enkephalin binding sites in rat brain membranes depleted of mu binding sites by pretreatment with the irreversible agent BIT. The two binding sites had lower (delta ncx-2, Ki = 96.6 nM) and higher (delta ncx-1, Ki = 1.55 nM) affinity for DPDPE. The ligand-selectivity profile of the delta ncx-1 site was that of a classic delta binding site. The ligand-selectivity profile of the delta ncx-2 site was neither mu- or delta-like. The Ki values of selected agents for the delta ncx-2 site were: [pCl]DPDPE (3.9 nM), DPLPE (140 nM), and DAMGO (2.6 nM). Under these assay conditions, [3H][D-Ala2,D-Leu5]enkephalin binding to the cells expressing the cloned mu receptor is very low and pretreatment of cell membranes with BIT almost completely inhibits [3H]DAMGO and [3H][D-Ala2,D-Leu5]enkephalin binding. Intracerebroventricular administration of antisense DNA to the cloned delta receptor selectively decreased [3H][D-Ala2,D-Leu5]enkephalin binding to the delta ncx-1 site. Administration of buprenorphine to rats 24 h prior to preparation of membranes differentially affected mu, delta ncx-1, and delta ncx-2 binding sites. Viewed collectively, these studies have identified a novel non-mu- non-delta-like binding site in rat brain.