A Breathing Zirconium Metal–Organic Framework with Reversible Loss of Crystallinity by Correlated Nanodomain Formation

The isoreticular analogue of the metal–organic framework UiO‐66(Zr), synthesized with the flexible trans‐1,4‐cyclohexanedicarboxylic acid as linker, shows a peculiar breathing behavior by reversibly losing long‐range crystalline order upon evacuation. The underlying flexibility is attributed to a concerted conformational contraction of up to two thirds of the linkers, which breaks the local lattice symmetry. X‐ray scattering data are described well by a nanodomain model in which differently oriented tetragonal‐type distortions propagate over about 7–10 unit cells.     

Feature of solid–liquid metals reaction revealed by conversion electron Mössbauer spectrometry

Selective electrolytic dissolution of the η-zinc layer of continuous galvanized steel sheet has been utilized to uncover the Fe–Al intermetallic layer which inhibits the formation of other binary Fe–Zn intermetallic compounds. The characterization of the Fe–Al–Zn compounds by scanning electron microscopy, Mössbauer spectrometry and semi-grazing X-ray diffraction brings new enlightment about the conditions which control nucleation and growth as well as collapse of the inhibition layer and the resulting morphology of the coating.     

Narrow stripe semiconductor laser for improved performance of optical communication systems

A narrow stripe (GaAl) As/GaAs laser is described, which has low source noise, high linearity and an expected life in excess of 20,000 hours. It has a short coherence length compared with a self-focused or refractive index guided laser giving very good modal noise performance. It is suitable for all digital systems and all but the most demanding amplitude modulated analogue systems.     

3,4-Methylenedioxymethamphetamine (MDMA) and metabolites disposition in blood and plasma following controlled oral administration

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit phenethylamine ingested for entactogenic and euphoric effects. Although blood is more commonly submitted for forensic analysis, previous human MDMA pharmacokinetics research focused on plasma data; no direct blood–plasma comparisons were drawn. Blood and plasma specimens from 50 healthy adult volunteers (33 males, 17 females, 36 African-American) who ingested recreational 1.0 and 1.6 mg/kg MDMA doses were quantified for MDMA and metabolites 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-methylenedioxyamphetamine (MDA), and 4-hydroxy-3-methoxyamphetamine (HMA) by two-dimensional gas chromatography–mass spectrometry. Specimens were collected up to 3 h post-dose and evaluated for maximum concentration (C _max), first detection time (t _first), time of C _max (t _max), and 3-h area under the curve (AUC_0–3 h); as well as blood metabolite ratios and blood/plasma ratios. Median blood MDMA and MDA C _max were significantly greater (p?<?0.0005) than in plasma, but HMMA was significantly less (p?<?0.0005). HMA was detected in few blood specimens, at low concentrations. Nonlinear pharmacokinetics were not observed for MDMA or MDA in this absorptive phase, but HMMA C _max and AUC_0–3 h were similar for both doses despite the 1.6-fold dose difference. Blood MDA/MDMA and MDA/HMMA significantly increased (p?<?0.0001) over the 3-h time course, and HMMA/MDMA significantly decreased (p?<?0.0001). Blood MDMA C _max was significantly greater in females (p?=?0.010) after the low dose only. Low-dose HMMA AUC_0–3 h was significantly decreased in females’ blood and plasma (p?=?0.027) and in African-Americans’ plasma (p?=?0.035). These data provide valuable insight into MDMA blood–plasma relationships for forensic interpretation and evidence of sex- and race-based differential metabolism and risk profiles.

Derivative of an integral over a convex polytope

Many problems in optimization lead to a cost function in the form of an integral over a polytope. To find the gradient or Hessian of such costs one needs to take the derivative of an integral over a convex polytope with respect to the parameters defining the polytope. The contribution of the current paper is to present a formula for such derivatives.     

The half-life of <Superscript>198</Superscript>Au : High-precision measurement shows no temperature dependence

We have measured the half-life of the β -decay of ¹⁹⁸Au in a metallic environment, both at low temperature (19K), and also at room temperature. We find the half-lives at both temperatures to be the same within 0.04%, a finding that contradicts a recent report of a 3.6±1.0 % difference in the ¹⁹⁸Au half-life when measured at essentially the same two temperatures. Our results for the half-life, 2.6949±0.0009 d at room temperature and 2.6953±0.0008 d at 19K, also agree well with previous precision room temperature measurements.     

Prehomogeneous spaces for Borel subgroups of general linear groups

Let k be an algebraically closed field. Let B be the Borel subgroup of GL_n(k) consisting of nonsingular upper triangular matrices. Let b = Lie B be the Lie algebra of upper triangular n × n matrices and u the Lie subalgebra of b consisting of strictly upper triangular matrices. We classify all Lie ideals n of b, satisfying u' ⫅ n ⫅ u, such that B acts (by conjugation) on n with a dense orbit. Further, in case B does not act with a dense orbit, we give the minimal codimension of a B-orbit in n. This can be viewed as a first step towards the difficult open problem of classifying of all ideals n ⫅ u such that B acts on n with a dense orbit. The proofs of our main results require a translation into the representation theory of a certain quasi-hereditary algebra A_t,1. In this setting we find the minimal dimension of Ext¹A_t,1(M,M) for a δ-good A_t,1-module of certain fixed δ-dimension vectors.     

Molecular Sensors for Moisture Detection by Mössbauer Spectroscopy

A parameter of importance in various industrial and commercial applications is sensitivity to moisture. A new class of molecular sensors which enable the qualitative and quantitative determination of air moisture (high selectivity and sensitivity) by application of Mössbauer spectroscopy as the probe technique has been investigated. The electronic properties of the iron-containing sensor depend upon the presence of moisture which is taken up by it and this process is accompanied by a change in electronic spin ground state which can be detected by Mössbauer spectroscopy. The sensor is suitable for in-field and industrial application using the recently developed Mössbauer spectrometer MIMOS II. Possible suitability for the detection of moisture in extraterrestrial environments is considered.     

Estimation with Missing Data

This paper reviews estimation problems with missing, or hidden data. We formulate this problem in the context of Markov models and consider two interrelated issues, namely, the estimation of a state given measured data and model parameters, and the estimation of model parameters given the measured data alone. We also consider situations where the measured data is, itself, incomplete in some sense. We deal with various combinations of discrete and continuous states and observations.