Unusual and Tunable Negative Linear Compressibility in the Metal-Organic Framework MFM-133(M) (M = Zr, Hf).

High-pressure single-crystal X-ray structural analyses of isostructural MFM-133(M) (M = Zr, Hf) of flu topology and incorporating the tetracarboxylate ligand TCHB4- [H4TCHB = 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-1,1'-biphenyl] and {M6(µ3-OH)8(OH)8(COO)8} clusters confirm negative linear compressibility (NLC) behavior along the c axis. This occurs via a three-dimensional wine-rack NLC mechanism leading to distortion of the octahedral cage toward a more elongated polyhedron under static compression. Despite the isomorphous nature of these two structures, MFM-133(Hf) shows a higher degree of NLC than the Zr(IV) analogue. Thus, for the first time, we demonstrate here that the NLC property can be effectively tuned in a framework material by simply varying the inorganic component of the frameworks without changing the network topology and structure.

Crystal structure of {2,2'-[ethyl-enebis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}oxidovanadium(IV) methanol monosolvate.

Two independent mol-ecules of the title solvated complex, [V(C16H14N2O2)O]·CH3OH, also known as [N,N'-bis-(salicyl-idene)ethyl-enedi-amine]-oxidovanadium(IV) or vanadyl salen, crystallize in the asymmetric unit. Each disordered methanol solvent mol-ecule [occupancy ratios 0.678 (4):0.322 (4) and 0.750 (5):0.250 (5)] is linked to a [N,N'-bis-(salicyl-idene)ethyl-enedi-amine]-oxidovanadium(IV) mol-ecule by an O-H⋯O hydrogen bond and to others by C-H⋯O hydrogen bonds. The resulting extended structure consists of a bilayer of mol-ecules parallel to the ab plane. Despite the fact that solvates are common in complexes derived from substituted analogues of the N,N'-bis-(salicyl-idene)ethyl-enedi-amine ligand, the title solvate is the first one of [N,N'-bis-(salicyl-idene)ethyl-enedi-amine]-oxidovanadium(IV) to be structurally characterized. The two vanadyl species have very similar inter-nal geometries, which are best characterized as distorted square-based pyramidal with the vanadium atom displaced from the N2O2 basal plane by 0.5966 (9) Šin the direction of the doubly-bonded oxide ligand.

Aurophilicity under pressure: a combined crystallographic and in situ spectroscopic study.

High pressure crystallographic studies on [1,4-C6H4{PPh2(AuCl)}2] (1) reveal the largest pressure-induced contraction of an aurophilic interaction observed for any Au(i) complex; Hirshfeld surface analysis and Raman spectroscopy reveal the presence of several types of intermolecular interaction, which play an important role in the behaviour of 1 as a function of pressure.

Postembryonic Nephrogenesis and Persistence of Six2-Expressing Nephron Progenitor Cells in the Reptilian Kidney.

New nephron formation (nephrogenesis) ceases in mammals around birth and is completely absent in adults. In contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. The transient mesonephros in reptiles (including birds) and mammals is replaced by the metanephros during embryogenesis. Thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. Previous reports have suggested the metanephros of non-avian reptiles (hereafter reptiles) may continually form nephrons throughout life. We investigated the presence of adult nephrogenesis in reptiles by examining adult kidneys from several species including Trachemys scripta, Chrysemys picta, Boa constrictor, Tupinambis tegu, Anolis carolinensis, and Alligator mississipiensis among others. We found that all major reptilian groups (Testudines, Crocodylia, and Squamates) showed the presence of adult nephrogenesis. The total amount of nephrogenesis varied greatly between species with turtles displaying the highest density of nephrogenesis. In contrast, we were unable to detect adult nephrogenesis in monotremes, and in the iguanid A. carolinensis. Nephron progenitor cells express the transcription factor Six2, which in mammals, becomes downregulated as the progenitor cell population is exhausted and nephrogenesis ends. Using the alligator as a model, we were able to detect Six2-positive cap mesenchyme cells in the adult kidney, which spatially correlated with areas of nephrogenesis. These results suggest that the metanephric kidney of reptiles has maintained the ability to continually grow new nephrons during postembryonic life, a process lost early in mammalian evolution, likely due to the persistence of a Six2-expressing progenitor cell population.

Epitaxial Retrieval of a Disappearing Polymorph.

Recrystallization of [PdCl2([9]aneS2O)] ([9]aneS2O = 1-oxa-4,7-dithiacyclononane), 1, and [PtCl2([9]aneS2O)], 2, by diffusion of Et2O vapor into solutions of the complexes in MeNO2 yielded three phases of 1 and two phases of 2. The known phase of 1, herein designated α-1, was obtained under ambient conditions. A second phase, designated ß-1, was initially also obtained by this method; however, following the advent of a third phase, γ-1, all subsequent efforts over a period of a year to crystallize ß-1 yielded either γ-1, obtained by carrying out the recrystallization at elevated temperature, or α-1, commonly found throughout the study. This persistent absence of a phase which could initially be crystallized with ease led us to the conclusion that ß-1 was an example of a "disappearing polymorph". The first phase obtained of 2, designated α-2, was obtained by recrystallization under ambient conditions and is isomorphous and isostructural with α-1. The second phase ß-2 was obtained by slight elevation of the recrystallization temperature and was found to be isomorphous and isostructural with ß-1. Subsequently, ß-2 was used to seed the growth of the disappearing polymorph ß-1. No third phase of 2 (γ-2) has been isolated thus far.

Drug shortages as an impetus to improve parenteral nutrition practices.

PURPOSE: A medical center's implementation of adult and pediatric parenteral nutrition (PN) algorithms and other strategies for managing PN ingredient shortages are described. SUMMARY: In response to nationwide shortages of amino acids and other PN ingredients in 2010, a large Massachusetts teaching hospital undertook a quality-improvement initiative to ensure appropriate patient selection for PN therapy. A clinical pharmacist was designated as a nutrition support leader with responsibility for the management of PN practices. Clinical pharmacists collaborated with clinical dietitians to establish PN eligibility criteria based on established practice guidelines and developed evidence-based adult and pediatric nutrition support algorithms. In addition, (1) physicians were required to obtain a nutrition service consultation before initial prescribing of PN therapy, (2) the initial ordering of PN therapy through the computerized prescriber-order-entry (CPOE) system was restricted to clinical dietitians and clinical pharmacists, (3) the use of premixed PN solutions at the discretion of dietitians was increased, and (4) the practice of adding i.v. multivitamins and trace elements to PN solutions was restricted. During the first year after implementation of the PN algorithms, CPOE restrictions, and other process changes, PN orders were reduced by an average of five orders per day relative to the preceding 11-month period, helping to ensure continued patient access to PN therapy. CONCLUSION: PN ingredient shortages prompted changes in the decision-making process for the prescription of PN. Guidelines for ordering PN were successfully implemented and allowed for the appropriate selection of qualified patients and the management of PN ingredient shortages.