Molecular dynamics and kinetics of isothermal cold crystallization with tunable dimensionality in a molecular glass former, 5'-(2,3-difluorophenyl)-2'-ethoxy-4-pentyloxy-2,3-difluorotolane.

This paper characterizes the molecular mobility that triggers the cold crystallization abilities in 5'-(2,3-difluorophenyl)-2'-ethoxy-4-pentyloxy-2,3-difluorotolane (short name DFP25DFT) material by broadband dielectric spectroscopy (BDS). We analyze the properties of identified molecular motions by referring to the Vogel-Fulcher-Tammann (VFT) model for the structural α-process associated with molecular rotation in isotropic liquid and the Eyring and Starkweather approach for the thermally activated processes, ß-process related to intramolecular movement in liquid and glassy state and emerging during cold crystallization α'-process ascribed to confined movements of molecules located adjacent to crystalline surfaces. To characterize the material, we employ single-crystal X-ray diffraction, differential scanning calorimetry (DSC), adiabatic calorimetry, and polarizing optical microscopy (POM), while we utilize molecular mechanics simulations (MM2) to explore molecular flexibility. Our study focuses on inter- and intramolecular interactions that determine the cold-crystallization tendency. We demonstrate that the solidification path is controlled by the fragility of the system, the dipole-dipole attraction, and the intramolecular dynamics. The study of cold crystallization kinetics under isothermal conditions reveals the complexity of the process: the formation of two crystalline phases, Cr2 and Cr3, proceeding in different modes. This feature discloses the possibility of switching the crystal growth between three- and two-dimensional in the cold-crystallization process driven by different mechanisms.

Structure and molecular packing in smectic BCr and Ad phases of Schiff base liquid crystal compounds through the analyses of layer spacing, entropy and crystal structure.

Single-crystal structural analyses and heat capacity measurements were performed on two Schiff base liquid crystal compounds, 5CBAA (4-chlorobenzylidene-4'-pentyloxyaniline) and 5ABCA (4-pentyloxybenzylidene-4'-chloroaniline). The alkyloxy-chain of a 5CBAA molecule was conformationally ordered in the crystal at room temperature. While that of 5ABCA was partially disordered in the room temperature phase but ordered in a low-temperature phase at 100 K. The structural phase transition involving the disordering of the conformation was observed at 107 K in the heat capacity of 5ABCA. Both compounds showed two liquid crystalline phases, SmBCr and SmAd. The net entropy change associated with the chain disordering was essentially the same in them despite the difference in the orientation of their central -CH[double bond, length as m-dash]N- moiety. The layer-spacings of SmBCr and SmAd phases were analyzed for their chain-length dependence in both series of mesogens (nCBAA and nABCA), as well as in the case of nBBAA (4-bromobenzylidene-4'-alkyloxyaniline). The results reveal that these smectic structures are composed of alternately stacked core- and chain-layers with an antiparallel arrangement of cores and a bent-form of molecules.

Cell-quintupling: Structural phase transition in a molecular crystal, bis(trans-4-butylcyclohexyl)methanol.

A structural phase transition at 151.6 K of the title compound [bis(trans-4-butylcyclohexyl)methanol] is examined by X-ray diffraction crystallography, Fourier-transform infrared spectroscopy, and adiabatic calorimetry. A general consideration on possible superstructures indicates that a single modulation wave is sufficient to drive this cell-quintupling transition. The entropy of transition determined calorimetrically indicates that two conformations are dominant in the room-temperature phase in contrast to the fivefold disorder expected from the structure of the low-temperature phase.

Reassessment of structure of smectic phases: nano-segregation in smectic E phase in 4-n-alkyl-4'-isothiocyanato-1,1'-biphenyls.

Based on new diffraction data from aligned samples of smectic E (SmE) phase of 4-n-alkyl-4'-isothiocyanato-1,1'-biphenyls, systematics against the alkyl chain length n is analyzed. In order to perform the analysis, the molecular form factor approximated by a box-shaped distribution is calculated while taking the rounding of the distribution at corners into account. The analysis clearly shows the nano-segregated layered structure, which does not fit to the traditional structural view of SmE phase but does fit to the model the present authors proposed recently. Some implications of this conclusion are discussed in relation to the importance of the molten state of alkyl chains in most of real mesogens revealed previously through thermodynamic analyses.

Solid-state thiotropolone: an extremely rapid intramolecular proton transfer.

Through variable-temperature solution-state NMR and molten- and solid-state CP/MAS (13)C NMR spectra, thiotropolone is found to exist as two rapidly equilibrated tautomeric structures, thione and enethiol, even in the solid state far below the melting point. The crystal structure shows an almost perpendicular packing, suggesting that the intramolecular hydrogen bond is dominant.

Negative thermal expansion emerging upon structural phase transition in ZrV2O7 and HfV2O7.

ZrV(2)O(7) and HfV(2)O(7), which show negative thermal expansion (NTE) in the high-temperature phase, were investigated using X-ray diffraction and heat capacity calorimetry. Two sharp anomalies due to successive phase transitions were observed in the temperature dependence of heat capacity at 345.5 K and 373.4 K for ZrV(2)O(7) and 341.8 K and 370.3 K for HfV(2)O(7). The smallness of their combined entropies of transition suggested that the phase transitions are of displacive type. Effective phonon densities of states (DOS) described by a simple model, and mode-Grüneisen parameters of the low-temperature phase were obtained through the spectrum analyses of heat capacities of ZrV(2)O(7) and HfV(2)O(7). Their effective phonon DOS's show the three features common to NTE compounds: low-energy phonon mode, high-energy phonon mode, and a wide phonon gap in between. The mode-Grüneisen parameter of low-energy modes corresponding to translational and librational vibrations of the constituent polyhedra is negative but with a small absolute value due to the distortion of V(2)O(7) group in the low-temperature phase, resulting in positive thermal expansion. It is revealed that the release of the structural distortion upon the successive phase transitions with large volume increase leads to the NTE of ZrV(2)O(7) and HfV(2)O(7) in the high-temperature phase.

Serum hepcidin-20 is elevated during the acute phase of myocardial infarction.

Hepcidin, a key iron-regulator secreted from the liver, consists of 25 amino acids (hepcidin-25), blocks iron release from macrophages via internalization and degradation of cellular iron exporter ferroportin, and restrains the use of iron in organs. Hepcidin mRNA and protein are also expressed in the human heart. A short form of hepcidin that lacks 5 amino-acid residues in the N-terminus (hepcidin-20) has been found in human serum, although its physiological role is unknown. Here, we successfully measured the serum levels of hepcidin-25 and hepcidin-20 in 12 patients with acute myocardial infarction (AMI) using surface-enhanced laser desorption ionization time of flight mass spectrometry. Among the selected 10 patients, whose blood samples were taken within 4 hours after a heart attack, all the patients showed elevated serum levels of hepcidin-20 [between 31.7 and 285.1 arbitrary unit (AU); normal level < 9.3 AU], while 8 patients showed high levels of hepcidin-25 (9.3-271.4; normal < 25.5 AU). The hepcidin-20 level was decreased to nearly the normal level on day 7 (range of 2.9 to 12.5 AU) in the 12 patients, whereas the hepcidin-25 level remained high on day 7 in 8 patients. Furthermore, the elevated levels of hepcidin-25 and hepcidin-20 were not correlated with the serum levels of markers for inflammation, interleukin-6 and C-reactive protein, in the patients with AMI. In conclusion, the serum hepcidin-20 is transiently elevated in response to acute cardiac ischemia. Measurement of serum hepcidin-20, rather than hepcidin-25, is helpful for diagnosis of acute myocardial infarction.

Beneficial effect of desialylated erythropoietin administration on the frozen-thawed canine ovarian xenotransplantation.

PURPOSE: The main drawback of ovarian cryopreservation followed by transplantation is that a large proportion of follicles are lost after transplantation. Thus, effects of erythropoietin (EPO) and desialylated EPO administration on the frozen-thawed canine ovarian xenotransplantation were examined. METHODS: The protective and survival-promoting effects of EPO and desialylated EPO on the follicles of frozen-thawed canine ovaries after transplantation were examined using NOD-SCID mice. Frozen-thawed dog ovarian tissue with 400 U/kg of EPO or asialo EPO was placed into the ovarian bursa. RESULTS: At 4 weeks after the transplantation, the ovaries were removed and subjected to histological examination. The survival rate of early primary follicles was 15.2% in the EPO group and 157.6% in the asialo EPO group, in contrast to 10.1% in the untreated group. CONCLUSIONS: These results demonstrate that administration of asialo EPO could be effectively used to enhance the survival of the follicles of transplanted cryopreserved ovaries.

One-dimensional correlation in the dipolar Ising crystal tricyclohexylmethanol: crystal structure revisited and heat capacity.

The crystal structure of an organic weak-ferroelectrics, tricyclohexylmethanol (TCHM), was re-examined by single-crystal x-ray diffraction at room temperature. TCHM forms a dimer through hydrogen bonding at the centre of the dimer, where two hydroxyl groups are arranged in tandem and their direction is disordered in two possible orientations, which brings about a dipolar Ising nature. The heat capacity measured by adiabatic calorimetry from 6 to 400 K shows three anomalies including fusion at 368 K. The entropy of the ferroelectric transition is 1.9 J K(-1) mol(-1), supporting the order-disorder mechanism of dimer dipoles. A broad anomaly at 348 K is related to the breakage of the intra-dimer hydrogen bond. Detailed analysis of the temperature dependence of heat capacity due to the phase transition showed the presence of a broad hump in the excess heat capacity around 160 K. The temperature dependences of the excess heat capacity and the existing dielectric constant can be analysed in terms of a highly anisotropic Ising model.

Beneficial effect of erythropoietin administration on murine infection with Trypanosoma congolense.

The effect of erythropoietin treatment on Trypanosoma congolense infection in mice was studied. Survival rates of mice were dramatically improved by treatment with recombinant human erythropoietin (r-hu-EPO; 5,000 U/kg) when infected with 1,000 cells of T. congolense IL3000 (P < 0.05). All the untreated mice infected with T. congolense IL3000 died by day 9 of infection; however, 100%, 50%, and 25% of the mice treated with r-hu-EPO for 8 days survived to day 20, day 40, and day 60 of the parasitical infection, respectively. Anti-8-hydroxy-2'-deoxyguanosine antibody, a biomarker for oxidative damage of DNA, yielded positive reactions in the cytoplasm of the parasites recovered from the mice treated with r-hu-EPO. These results, taken together, indicate that erythropoietin administration is effective for the treatment of T. congolense infection.

Effect of intramolecular pi-pi and CH-pi interactions between ligands on structure, electrochemical and spectroscopic properties of fac-[Re(bpy)(CO)3(PR3)]+(bpy = 2,2'-bipyridine; PR3= trialkyl or triarylphosphines).

Intramolecular pi-pi and CH-pi interactions between the bpy and PR3 ligands of fac-[Re(bpy)(CO)3(PR3)]+ affect their structure, and electrochemical and spectroscopic properties. Intramolecular CH-pi interaction was observed between the alkyl groups on the phosphine ligand (R =nBu, Et) and the bpy ligand, and intramolecular pi-pi and CH-pi interactions were both observed between the aryl group(s) on the phosphorus ligand (R =p-MeOPh, p-MePh, Ph, p-FPh, OPh) and the bpy ligand, while no such interactions were found in the trialkylphosphite complexes (R = OiPr, OEt, OMe). The intramolecular interactions distort the pyridine rings of the bpy ligand as long as 3.7 x 10(-2)A in crystals. Molecular orbital calculations of the bpy ligand suggest that this distortion decreases the energy gap between its pi and pi* orbitals. An absorption band attributed to the pi-pi*(bpy) transition of the distorted rhenium complexes, measured in a KBr pellet, was red-shifted by 1-5 nm compared to the complexes without the distorted bpy ligand. Even in solution, similar red shifts of the pi-pi*(bpy) absorption were observed. The redox potential E1/2(bpy/bpy*-) of the complexes with the trialkylphosphine and triarylphosphine ligand are shifted positively by 110-120 mV and 60-80 mV respectively, compared with those derived from the electron-attracting property of the phosphorus ligand. In contrast with these properties, three nu(CO) IR bands, which are sensitive to the electron density on the central rhenium because of pi-back bonding, were shifted to higher energy, and a Re(I/II)-based oxidation wave was observed at a more positive potential according to the electron-attracting property of the phosphorus ligand.

BCG effects on telomerase activity in bladder cancer cell lines.

BACKGROUND: Although intravesical bacillus Calmette-Guerin (BCG) therapy is very effective in the treatment of and prophylaxis against superficial bladder cancer, its exact mechanism of action is not clear. In this study, the effect of BCG on telomerase activity was examined in the T24 and J82 bladder cancer cell lines, the ACHN human renal cell carcinoma cell line, and the PC-3 human prostate cancer cell line. METHODS: T24 and J82 cells were cocultured with BCG for 5 days. Telomerase activity was measured by telomeric repeat amplification protocol. Cell-cycle phase was determined by FACS analysis. RESULTS: Telomerase activity in all cell lines provided high absorbance. Telomerase activity in BCG-treated T24 and J82 cells was significantly decreased when compared with that in the nontreated cells. On the other hand, telomerase activity did not change in ACHN and PC-3 cells after they had been cocultured with BCG. In BCG-treated T24 cells and J82 cells, apoptotic cells were markedly increased compared with those in the nontreated cells. CONCLUSION: These results suggest that the reduction of telomerase activity is related to the mechanism of BCG effects. Possible mechanisms to be considered are either that BCG inhibits telomerase first, or that it induces apoptosis and decreases telomerase activity as a result of this induction.