Form II of monoclinic methyl β‐carboline‐3‐carboxyl­ate

The crystal structure of the second monoclinic P2₁/c form of the β‐carboline‐3‐carboxyl­ate, C₁₃H₁₀N₂O₂, has been determined. Very small changes in the packing scheme lead to a different unit cell; the role of weak C—H?O hydrogen bonds seems to be crucial.     

Einkristalluntersuchungen am Zeolithgermanat Tl3HGe7O16·4H2O

Ohne ZusammenfassungMit 1 Abbildung     

Über die Thalliumgermanate Tl2Ge4O9 und Tl2Ge6O13

Zusammenfassung Nach Dehydratation des Germanat-Zeoliths Tl₃HGe₇O₁₆· · 4 H₂O bildet sich bei 650°C das zu Me₂Ge₄O₉ (Me=Na, K, Rb) isotype Thalliumtetragermanat. Durch Entwässerung bei 700°C entsteht aus dem Zeolith ein stabiles Hexagermanat Tl₂Ge₆O₁₃, welches auch aus Schmelzen der Zusammensetzung Tl₂O:GeO₂=1:6 gewonnen wird. Mit Hilfe von DK- undWeissenberg-Aufnahmen werden für die rhombische Elementarzelle die Gitterparameter:a=37,24₇,b=13,74₃ undc=4,73₃ kX·E. ermittelt. Wahrscheinliche Raumgruppe ist D _2h ¹⁷ .     

Mediating stochastic switching of single molecules using chemical functionality

We have studied oligo(phenylene-ethynylene)s inserted into amide-containing alkanethiol self-assembled monolayers using scanning tunneling microscopy to demonstrate switching based on chemical functionality of the environment of the inserted molecules. The molecules show stability in two conductance states: an ON and an OFF state. We demonstrate bias-dependent switching due to hydrogen bonding between the inserted oligo(phenylene-ethynylene) and the matrix molecules. In addition, the inserted molecules exhibit fewer switching events than previously reported for alkanethiol matrixes, which we attribute to the rigidity of the hydrogen-bonded matrix.     

Visual screening for JAK2V617F mutation by a disposable dipstick

During the last 5 years, it was discovered that the JAK2V617F somatic mutation is present in virtually all patients with polycythemia vera and a large proportion of patients with essential thrombocythemia, primary myelofibrosis, and refractory anemia with ring sideroblasts and thrombocytosis. As a result, JAK2V617F was incorporated as a new clonal marker in the 2008 revision of the WHO diagnostic criteria. Current methods for JAK2 genotyping include direct sequencing, pyrosequencing, allele-specific PCR with electrophoresis, restriction fragment length polymorphism, real-time PCR, DNA-melting curve analysis, and denaturing HPLC. Some of these methods are labor intensive and time consuming, while the others require specialized costly equipment and reagents. We report a method for direct detection of the JAK2V617F allele by the naked eye using a dipstick test in a dry-reagent format. The method comprises a triprimer PCR combined with visual detection of the products within minutes by the dipstick test. Specialized instrumentation is not involved. The requirements for highly qualified technical personnel are minimized. Because the detection reagents exist in dry form on the dipstick, there is no need for multiple pipetting and incubation steps.     

Regularity of volume-minimizing flows on 3-manifolds

In Johnson and Smith (Indiana Univ Math J 44:45–85, 1995; Ann Global Anal Geometry 30:239–287, 2006; Proceedings of the VII International Colloquium on Differential Geometry, 1994, World Scientific, pp. 81–98), the authors characterized the singular set (discontinuities of the graph) of a volume-minimizing rectifiable section of a fiber bundle, showing that, except under certain circumstances, there exists a volume-minimizing rectifiable section with the singular set lying over a codimension-3 set in the base space. In particular, it was shown that for 2-sphere bundles over 3-manifolds, a minimizer exists with a discrete set of singular points. In this article, we show that for a 2-sphere bundle over a compact 3-manifold, such a singular point cannot exist. As a corollary, for any compact 3-manifold, there is a C ¹ volume-minimizing one-dimensional foliation. In addition, this same analysis is used to show that the examples, due to Pedersen (Trans Am Math Soc 336:69–78, 1993), of potentially volume-minimizing rectifiable sections (rectifiable foliations) of the unit tangent bundle to S ²ⁿ⁺¹ are not, in fact, volume minimizing.      

The antiferromagnetic structures of TbCu2Ge2 and HoCu2Ge2 by neutron diffraction

The magnetic structures of TbCu₂Ge₂ and HoCu₂Ge₂ were studied by neutron diffraction. At 293 K the chemical structure is tetragonal body centered, space group I 4/mmm. The magnetic cell at 4.2 K is four times larger than the chemical one with a wave vector $\text{k =}\text{1}\text{2}\text{0}\text{1}\text{2}$. The magnetic space group is triclinic P_a$\text{1}$(Sh₂⁷) for both compounds. The moment values and directions are μ_Tb = 8.48(6) [μ_B] along [110] tetr. and μ_HO = 6.5(1)[μ_B] making an angle of 81.4(°) with c and 80(°) with a₁. The structure consists of ferromagnetic (101) layers stacked antiferromagnetically.     

Stereocontrolled synthesis of a d-amicetose functionalised tetrahydroxanthone related to kigamicin A

A glycosylated tetrahydroxanthone mimicking the ABC subunit of kigamicin A is synthesised in five steps by a sequence that exploits a Pd catalysed C–O bond forming reaction to construct the tetrahydroxanthone nucleus; chemo- and enantioselective Ru-catalysed transfer hydrogenation to establish the C-14 hydroxyl stereochemistry in the A-ring; and a trichloroacetimidate activated donor to introduce the β-linked d-amicetose unit in a stereoselective manner.     

Genotyping of single nucleotide polymorphisms by primer extension reaction and a dual-analyte bio/chemiluminometric assay

Primer extension reaction (PEXT) is the most widely used approach to genotyping of single nucleotide polymorphisms (SNP). It is based on the high accuracy of nucleotide incorporation by the DNA polymerase. We propose a dual-analyte bio/chemiluminometric method for the simultaneous detection of the PEXT reaction products of the normal and mutant allele in a high sample-throughput format. PCR-amplified DNA fragments that span the SNP of interest are subjected to two PEXT reactions using normal and mutant primers in the presence of digoxigenin-dUTP and biotin-dUTP. Both primers contain a d(A)₃₀ segment at the 5′-end but differ in the final nucleotide at the 3′-end. Under optimized conditions only the primer that is perfectly complementary with the interrogated DNA will be extended by DNA polymerase and lead to a digoxigenin- or biotin-labeled product. The products of the PEXT reactions are mixed, denatured, and captured in microtiter wells through hybridization with immobilized oligo(dT) strands. Detection is performed by adding a mixture of antidigoxigenin–alkaline phosphatase (ALP) conjugate and a streptavidin–aequorin conjugate. The flash-type bioluminescent reaction of aequorin is triggered by the addition of Ca²⁺. ALP is then measured by adding the appropriate chemiluminogenic substrate. The method was evaluated by genotyping two SNPs of the human mannose-binding lectin gene (MBL2) and one SNP of the cytochrome P450 gene CYP2D6. Patient genotypes showed 100% concordance with direct DNA sequencing data.     

Rewritable Optical Storage with a Spiropyran Doped Liquid Crystal Polymer Film

Rewritable optical storage has been obtained in a spiropyran doped liquid crystal polymer films. Pictures can be recorded on films upon irradiation with UV light passing through a grayscale mask and they can be rapidly erased using visible light. Films present improved photosensitivity and optical contrast, good resistance to photofatigue, and high spatial resolution. These photochromic films work as a multifunctional, dynamic photosensitive material with a real‐time image recording feature.