Imprecise singing is widespread

There has been a recent surge of research on the topic of poor-pitch singing. However, this research has not addressed an important distinction in measurement: that between accuracy and precision. With respect to singing, accuracy refers to the average difference between sung and target pitches. Precision, by contrast, refers to the consistency of repeated attempts to produce a pitch. A group of 45 non-musician participants was asked to vocally imitate unfamiliar 5-note melodies, as well as to sing a series of familiar melodies from memory (e.g., Happy Birthday). The results showed that singers were more accurate than they were precise, and that a majority of participants could justifiably be categorized as imprecise singers. Accuracy and precision measures were correlated with one another, and conditional-probability analyses suggested that accuracy predicted precision more so than the converse. Finally, performance differences across groups of singers were greater for the imitation of unfamiliar tone sequences than for the recall of familiar melodies.     

The Preparation, Characterization and X-ray Structural Analysis of Tetrakis[1-Methyl-3-(2-Propyl)-2(3H)-Imidazolethione]Cadmium(II) Hexafluorophosphate

Abstract  A new compound, [Cd(mipit)₄][PF₆]₂ has been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit = 1-methyl-3-(2-propyl)-2(3H)-imidazolethione). The title compound crystallizes in tetragonal space group I4 ₁ /a with a = 12.478(2) ?, b = 12.478(2) ?, c = 28.806(6) ?, and Z = 4. The complex is a high melting, colorless solid that has a distorted tetrahedral CdS₄ coordination geometry. Thermogravimetric analysis results for the title compound as well as for another potential CdS synthon and two potential CdSe synthons are reported. Graphical Abstract  The synthesis and characterization of the title compound, a new ionic homoleptic cadmium complex, tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]cadmium(II) hexafluorophosphate is reported. The results of a single crystal X-ray diffraction analysis reveal a distorted tetrahedral CdS₄ coordination sphere about the cadmium. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Magnetic Relaxometry with an Atomic Magnetometer and SQUID Sensors on Targeted Cancer Cells

Magnetic relaxometry methods have been shown to be very sensitive in detecting cancer cells and other targeted diseases. Superconducting Quantum Interference Device (SQUID) sensors are one of the primary sensor systems used in this methodology because of their high sensitivity with demonstrated capabilities of detecting fewer than 100,000 magnetically-labeled cancer cells. The emerging technology of atomic magnetometers (AM) represents a new detection method for magnetic relaxometry with high sensitivity and without the requirement for cryogens. We report here on a study of magnetic relaxometry using both AM and SQUID sensors to detect cancer cells that are coated with superparamagnetic nanoparticles through antibody targeting. The AM studies conform closely to SQUID sensor results in the measurement of the magnetic decay characteristics following a magnetization pulse. The AM and SQUID sensor data are well described theoretically for superparamagnetic particles bound to cells and the results can be used to determine the number of cells in a cell culture or tumor. The observed fields and magnetic moments of cancer cells are linear with the number of cells over a very large range. The AM sensor demonstrates very high sensitivity for detecting magnetically labeled cells does not require cryogenic cooling and is relatively inexpensive.     

Bott periodicity and realizations of chiral symmetry in arbitrary dimensions

We compute the chiral symmetries of the Lagrangian for confining “vector-like” gauge theories with massless fermions in d-dimensional Minkowski space and, under a few reasonable assumptions, determine the form of the quadratic fermion condensates which arise through spontaneous breaking of these symmetries. We find that for each type (complex, real, or pseudoreal) of representation of the gauge group carried by the fermions, the chiral symmetries of the Lagrangian, as well as the residual symmetries after dynamical breaking, exactly follow the pattern of Bott periodicity as the dimension changes. The consequences of this for the topological features of the low-energy effective theory are considered.     

Engineering the interface between glucose oxidase and nanoparticles

The behavior of glucose oxidase (GOx) on gold nanoparticles (NPs) was investigated as a function of (1) NP surface chemistry, (2) stabilizing protein additives, and (3) protein microenvironment. GOx secondary structure and unfolding was probed by circular dichroism (CD) spectroscopy and fluorescence, and GOx enzymatic activity was measured by a colorimetric assay. We also examined the activity and structure of GOx after displacement from the NP surface. Generally, GOx behavior was negatively impacted by conjugation to the NP, and conjugation conditions could vary the influence of the NP. Surface chemistry and protein microenvironment could improve behavior, but addition of stabilizing proteins negatively influenced activity. After displacement from the NPs, GOx tended to remain unfolded, indicating that the interactions with the NP were irreversible.     

Vertical anisotropic microfibers for a gecko-inspired adhesive

Geckos are able to adhere strongly and release easily from surfaces because the structurally anisotropic fibers on their toes naturally exhibit force anisotropy based on the direction of articulation. Here, semicircular fibers, with varying amounts of contact area on the two faces, are investigated to ascertain whether fiber shape can be used to gain anisotropy in shear and shear adhesion forces. Testing of 10-μm-diameter polydimethylsiloxane (PDMS) fibers against a 4-mm-diameter flat glass puck show that shear and shear adhesion forces were two to five times greater when in-plane movement caused the flat face, rather than the curved face, of the fiber to come in contact with the glass puck. The directional adhesion and shear force anisotropy results are close to theoretical approximations using the Kendall peel model and clearly demonstrate how fiber shape may be used to influence the properties of the adhesive. This result has broad applicability, and by combining the results shown here with other current vertical and angled designs, synthetic adhesives can be further improved to behave more like their natural counterparts.     

Stereoselective UV sensing of 1,2-diaminocyclohexane isomers based on ligand displacement with a diacridylnaphthalene N,N'-dioxide scandium complex

Stereoselective displacement of diacridylnaphthalene N,N'-dioxide ligands, 1, from a scandium(III) complex can be used for quantitative detection of 1,2-diaminocyclohexane isomers. The diastereoselective sensing assay with Sc(syn-1)(2) shows excellent linearity between the sample de and the measured UV absorption change, and sensing of mixtures comprising both low and high de values gave results within 5% accuracy. All three stereoisomers of 1,2-diaminocyclohexane can be differentiated using Sc[anti-(-)-1](2) in the same ligand displacement assay.     

Detection and Quantitation of Afucosylated N-Linked Oligosaccharides in Recombinant Monoclonal Antibodies Using Enzymatic Digestion and LC-MS

The presence of N-linked oligosaccharides in the CH2 domain has a significant impact on the structure, stability, and biological functions of recombinant monoclonal antibodies. The impact is also highly dependent on the specific oligosaccharide structures. The absence of core-fucose has been demonstrated to result in increased binding affinity to Fcγ receptors and, thus, enhanced antibody-dependent cellular cytotoxicity (ADCC). Therefore, a method that can specifically determine the level of oligosaccharides without the core-fucose (afucosylation) is highly desired. In the current study, recombinant monoclonal antibodies and tryptic peptides from the antibodies were digested using endoglycosidases F2 and H, which cleaves the glycosidic bond between the two primary GlcNAc residues. As a result, various oligosaccharides of either complex type or high mannose type that are commonly observed for recombinant monoclonal antibodies are converted to either GlcNAc residue only or GlcNAc with the core-fucose. The level of GlcNAc represents the sum of all afucosylated oligosaccharides, whereas the level of GlcNAc with the core-fucose represents the sum of all fucosylated oligosaccharides. LC-MS analysis of the enzymatically digested antibodies after reduction provided a quick estimate of the levels of afucosylation. An accurate determination of the level of afucosylation was obtained by LC-MS analysis of glycopeptides after trypsin digestion.     

Effect of crown ethers on the ground and excited state reactivity of samarium diiodide in acetonitrile

Electron transfer from the ground and excited states of Sm[15-crown-5](2)I(2) complex to a series of electron acceptors (benzaldehyde, acetophenone, benzophenone, nitrobenzene, benzyl bromide, benzyl chloride, 1-iodohexane, and 1,4-dinitrobenzene) was investigated in acetonitrile. Electron transfer from the ground state of the Sm(II)-crown system to aldehydes and ketones has a significant inner sphere component indicating that the oxophilic nature of Sm(II) prevails in the system even in the presence of bulky ligands such as 15-crown-5 ether. Activation parameters for the ground state electron transfer were determined, and the values were consistent with the proposed mechanistic models. Since crown ethers stabilize the photoexcited states of Sm(II), the photochemistry of Sm[15-crown-5](2)I(2) system in solution state has been investigated in detail. The results suggest that photoinduced electron transfer from Sm(II)-crown systems to a wide variety of substrates is feasible with rate constant values as high as 10(7) M(-1) s(-1). The results described herein imply that the present difficulty of manipulating the extremely reactive excited state of Sm(II) in solution phase can be overcome through stabilizing the excited state of the divalent metal ion by careful design of the ligand systems.