Thermal expansion and spontaneous strain of KMnF3 near the 186 K-structural phase transition

Abstract

By means of high-angle double-crystal X-ray diffractometry (HADOX), the thermal expansivity of KMnF₃ has been determined. The linear thermal expansion coefficient along each crystallographic axis exhibits a divergent anomaly at the structural phase transition at 186 K. The critical exponents of these coefficients are determined: in the cubic phase α = 0.21 ± 3, and in the tetragonal phase α′ = 0.19 ± 3 for the a axis and α″ = 0.35 ± 3 for the c axis.

In addition, the critical exponent of the spontaneous strain, c/a ? 1, is determined to be 0.4248 ± 8, which is smaller than that of the order parameter 2β = 0.5714 ± 12. These values are reasonable if the transition occurs in the vicinity of a tricritical point.     

Investigation of the surface reactivity of a sol-gel derived glass in the ternary system SiO2-CaO-P2O5

A new glass formulation, with the molar composition 60% SiO₂-35% CaO-5% P₂O₅, was synthesized using the sol-gel process, for applications as biomaterial in orthopaedic or maxillo facial surgery. Pellets, made of glass powder, were uniaxially compacted and soaked in simulated body fluid (SBF) for up to 7 days at 37 °C to evaluate glass bioactivity. Ionic exchanges at the interface glass-SBF were evaluated by studying evolutions of calcium, phosphorus and silicon concentrations in SBF using ICP-OES. Changes in glass surface, and the formation of crystalline phases were analyzed using XRD, SEM, EDS and FTIR methods.Results form ICP-OES showed a high reactivity of the glass surface with a very high and continuous release of calcium, a limited glass dissolution and an uptake of phosphorous from SBF. Results from both FTIR and XRD analysis indicated that the glass surface was progressively covered by two different phases: CaCO₃ as calcite and a carbonated apatite layer. The formation of these phases, following two different schemas, was observed after 2 h of immersion and confirmed after 7 days. SEM micrographs and EDS analysis demonstrated that the main phase, a carbonated apatite, was present as micro-spheroids and the secondary phase, calcite, was materialized by agglomerates which have diameters up to 10-15 μm. These results are in accordance with a bioactive feature of the glass studied.     

Risks of Muscle Atrophy in Patients with Malignant Lymphoma after Autologous Stem Cell Transplantation

Objective: Muscle atrophy is associated with autologous stem cell transplantation (ASCT)-related outcomes in patients with malignant lymphoma (ML). However, the impact of ASCT on muscle mass remains unclear in patients with ML. The aims of this study were to investigate changes in muscle mass and risk profiles for muscle atrophy after ASCT. Method: We enrolled 40 patients with refractory ML (age 58 [20-74] years, female/male 16/24, body mass index (BMI) 21.1 kg/m² [17.1-29.6]). Psoas muscle mass was assessed using the psoas muscle index (PMI) before and after ASCT. Statistical analysis used: Independent factors associated with a severe decrease rate of change in PMI were evaluated by decision-tree analysis, respectively. Results: PMI was significantly decreased after ASCT (4.61 vs. 4.55 cm²/m²; P=0.0425). According to the decision-tree analysis, the regimen was selected as the initial split. The rates of change in PMI were −5.57% and −3.97% for patients administered MCEC and LEED, respectively. In patients who were administered LEED, the second branching factor was BMI. In patients with BMI < 20.3 kg/m², the rate of change in PMI was −7.16%. On the other hand, the rate of change in PMI was 4.05% for patients with BMI ≥ 20.3 kg/m². Conclusion: We demonstrated that muscle mass decreased after ASCT in patients with ML. Patients who received MCEC and patients with low BMI were at risk for a decrease in muscle mass.     

Flame-spread limit from interactive burning droplets in microgravity

This research conducted microgravity experiments on the flame spread over droplet-cloud elements with strong droplet interaction aboard Kibo on the ISS. The droplet-cloud element represents a local droplet pattern appearing in randomly distributed droplet clouds near the group-combustion-excitation limit and consists of small-droplet-spacing droplets and large-droplet-spacing droplets. As droplet-cloud elements, we used four n-decane droplets, Droplets C, B, A and L, placed at fiber intersections of two-dimensional SiC-fiber lattice with a 4-mm fiber interval in a combustion chamber. The flame spreads over the droplet-cloud element in order of Droplets C, B, A and L. The position of Droplet L relative to Droplet A was varied to investigate the flame-spread-limit distribution around burning Droplet A. The position of Droplet B relative to Droplet A was varied to investigate the effect of two-droplet interaction between Droplets B and A on the flame spread to Droplet L. The position of Droplet C relative to Droplet B was also varied to investigate the effect of three-droplet interaction among Droplets C, B and A. The results shows that in the case with the strong interaction by two or three interactive droplets, the high-temperature region is enlarged by the droplet interaction, centers near the center of mass of the interactive droplets and plays an important role in the flame-spread-limit distribution. Since the burning lifetime of Droplet A is finite, the flame-spread time from burning Droplet A to Droplet L is limited by burning lifetime of Droplet A and is less than 80% of the burning lifetime of Droplet A, which increases with the interactive effect. The flame-spread-limit distance from the center of mass of the interactive droplets increases with the burning lifetime.     

2-Hydroxy-5,5-dialkyl-δ-valerolactone derivatives as chiral dopants for practical ferroelectric liquid crystals

2-Hydroxy-5,5-dialkyl-δ-valerolactone derivatives have shown interesting properties as a chiral dopant for ferroelectric liquid crystals. In small amounts these compounds induce high magnitudes of spontaneous polarization and long helical pitches in the chiral nematic phase (N*). Alkyl chains attached at the C-5 position play an important role in these properties. Here we discuss the stereochemistry and ferroelectric properties of these lactones and compare them with those of 2-hydroxy-5-alkyl-δ-valerolactone derivatives reported previously. The ring structure of 5,5-dialkyl-δ-valerolactone is found to be a rigid 'pseudo-chair' conformation by *H NMR studies.     

An improved method for acetaldehyde determination in blood by high-performance liquid chromatography and solid-phase extraction

This study reports on an improved method for acetaldehyde (ACH) determination in blood by high-performance liquid chromatography (HPLC). In the case of HPLC analysis, ACH is generally converted to derivatives for ultraviolet detection (for example 2,4-dinitrophenylhydrazine [DNPH] derivative). Nevertheless, elevation of the background during protein precipitation, hydrazone synthesis, or both frequently results in a serious loss of accuracy and precision of the analysis. The method in this study is developed to minimize the increase in nonspecific ACH-DNPH with a view to optimize mainly the synthetic condition of ACH-DNPH. The background is decreased dramatically by gentle deproteination, optimization of the DNPH amount and reaction pH, and reversed-phase solid extraction for the elimination of excess DNPH reagent. The standard curves show good linearity between 0 and 100 microM and minimal background is observed, indicating that the method is useful for monitoring the ACH concentration in blood.     

Photochemical dechlorination of DDT catalyzed by a hydrophobic vitamin B12 and a photosensitizer under irradiation with visible light

Dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) was catalyzed by a hydrophobic vitamin B(12), heptamethyl cobyrinate perchlorate, with a visible light irradiation system containing a [Ru(ii)(bpy)(3)]Cl(2) photosensitizer, and the hydrophobic vitamin B(12) showed high catalytic efficiency and stability during the reaction.     

Study of the dissociation of a charge-reduced phosphopeptide formed by electron transfer from an alkali metal target

Doubly protonated phosphopeptide (YGGMHRQET(p)VDC) ions obtained by electrospray ionization were collided with Xe and Cs targets to give singly and doubly charged positive ions via collision-induced dissociation (CID). The resulting ions were analyzed and detected by using an electrostatic analyzer (ESA). Whereas doubly charged fragment ions resulting from collisionally activated dissociation (CAD) were dominant in the CID spectrum with the Xe target, singly charged fragment ions resulting from electron transfer dissociation (ETD) were dominant in the CID spectrum with the Cs target. The most intense peak resulting from ETD was estimated to be associated with the charge-reduced ion with H2 lost from the precursor. Five c-type fragment ions with amino acid residues detached consecutively from the C-terminal were clearly observed without a loss of the phosphate group. These ions must be formed by N--Calpha bond cleavage, in a manner similar to the cases of electron capture dissociation (ECD) and ETD from negative ions. Although the accuracy in m/z of the CID spectra was about +/-1 Th because of the mass analysis using the ESA, it is supposed from the m/z values of the c-type ions that these ions were accompanied by the loss of a hydrogen atom. Four z-type (or y--NH3, or y--H2O) ions analogously detached consecutively from the N-terminal were also observed. The fragmentation processes took place within the time scale of 4.5 micros in the high-energy collision. The present results demonstrated that high-energy ETD with the alkali metal target allowed determination of the position of phosphorylation and the amino acid sequence of post-translational peptides.     

Towards oligosaccharide library synthesis by fluorous mixture method

The synthesis of an oligosaccharide library by a fluorous tag method is reported here. Several acceptors and donors were mixed and glycosylated. The reaction mixture was purified by chromatography over fluorous HPLC to provide disaccharides in order of increasing fluorine content of the tag. This method could be applied to oligosaccharide libraries consisting of two sets of structural isomers.     

Minimizing a monotone concave function with laminar covering constraints

Let V be a finite set with |V|=n. A family F⊆2^V is called laminar if for all two sets X,Y∈F, X∩Y≠∅ implies X⊆Y or X⊇Y. Given a laminar family F, a demand function , and a monotone concave cost function , we consider the problem of finding a minimum-cost such that x(X)?d(X) for all X∈F. Here we do not assume that the cost function F is differentiable or even continuous. We show that the problem can be solved in O(n²q) time if F can be decomposed into monotone concave functions by the partition of V that is induced by the laminar family F, where q is the time required for the computation of F(x) for any . We also prove that if F is given by an oracle, then it takes Ω(n²q) time to solve the problem, which implies that our O(n²q) time algorithm is optimal in this case. Furthermore, we propose an algorithm if F is the sum of linear cost functions with fixed setup costs. These also make improvements in complexity results for source location and edge-connectivity augmentation problems in undirected networks. Finally, we show that in general our problem requires Ω(2^n/2q) time when F is given implicitly by an oracle, and that it is NP-hard if F is given explicitly in a functional form.