Characteristics of listener sensitivity to talker-specific phonetic detail

Previous research shows that listeners are sensitive to talker differences in phonetic properties of speech, including voice-onset-time (VOT) in word-initial voiceless stop consonants, and that learning how a talker produces one voiceless stop transfers to another word with the same voiceless stop [Allen, J. S., and Miller, J. L. (2004). J. Acoust. Soc. Am. 115, 3171-3183]. The present experiments examined whether transfer extends to words that begin with different voiceless stops. During training, listeners heard two talkers produce a given voiceless-initial word (e.g., pain). VOTs were manipulated such that one talker produced the voiceless stop with relatively short VOTs and the other with relatively long VOTs. At test, listeners heard a short- and long-VOT variant of the same word (e.g., pain) or a word beginning with a different voiceless stop (e.g., cane or coal), and were asked to select which of the two VOT variants was most representative of a given talker. In all conditions, which variant was selected at test was in line with listeners' exposure during training, and the effect was equally strong for the novel word and the training word. These findings suggest that accommodating talker-specific phonetic detail does not require exposure to each individual phonetic segment.     

The role of C-H and C-C stretching modes in the intrinsic non-radiative decay of triplet states in a Pt-containing conjugated phenylene ethynylene

The intrinsic non-radiative decay (internal conversion) from the triplet excited state in phosphorescent dyes can be described by a multi-phonon emission process. Since non-radiative decay of triplet excitons can be a significant process in organic light-emitting diodes, a detailed understanding of this decay mechanism is important if the overall device efficiency is to be controlled. We compare a deuterated Pt(II)-containing phenylene ethynylene with its non-deuterated counterpart in order to investigate which phonon modes control to the non-radiative decay path. We observe that deuteration does not decrease the non-radiative decay rate. A Franck-Condon analysis of the phosphorescence spectra shows that the electronic excitation is coupled strongly to the breathing mode of the phenyl ring and the C≡C carbon stretching modes, while high-energy C-H or C-D stretching modes play an insignificant role. We, therefore, associate the internal conversion process with the carbon-carbon stretching vibrations.     

Differential ordering of the protein backbone and side chains during protein folding revealed by site-specific recombinant infrared probes

The time scale for ordering of the polypeptide backbone relative to the side chains is a critical issue in protein folding. The interplay between ordering of the backbone and ordering of the side chains is particularly important for the formation of β-sheet structures, as the polypeptide chain searches for the native stabilizing cross-strand interactions. We have studied these issues in the N-terminal domain of protein L9 (NTL9), a model protein with mixed α/β structure. We have developed a general approach for introducing site-specific IR probes for the side chains (azide) and backbone ((13)C═(18)O) using recombinant protein expression. Temperature-jump time-resolved IR spectroscopy combined with site-specific labeling enables independent measurement of the respective backbone and side-chain dynamics with single residue resolution. We have found that side-chain ordering in a key region of the β-sheet structure occurs on a slower time scale than ordering of the backbone during the folding of NTL9, likely as a result of the transient formation of non-native side-chain interactions.     

A facile,one-pot procedure for the formation of benzimidazoles from esters using DABAL-Me3, an air stable source of AlMe3

A convenient, single-step, efficient synthesis of benzimidazoles from esters and diamines is reported. The methodology uses an air stable form of trimethylaluminum referred to as DABAL-Me₃ and is compatible with a wide range of functional groups, including acid-sensitive protecting groups.     

Characterization of the mupirocin biosynthesis gene cluster from Pseudomonas fluorescens NCIMB 10586

The polyketide antibiotic mupirocin (pseudomonic acid) produced by Pseudomonas fluorescens NCIMB 10586 competitively inhibits bacterial isoleucyl-tRNA synthase and is useful in controlling Staphylococcus aureus, particularly methicillin-resistant Staphylococcus aureus. The 74 kb mupirocin biosynthesis cluster has been sequenced, and putative enzymatic functions of many of the open reading frames (ORFs) have been identified. The mupirocin cluster is a combination of six larger ORFs (mmpA-F), containing several domains resembling the multifunctional proteins of polyketide synthase and fatty acid synthase type I systems, and individual genes (mupA-X and macpA-E), some of which show similarity to type II systems (mupB, mupD, mupG, and mupS). Gene knockout experiments demonstrated the importance of regions in mupirocin production, and complementation of the disrupted gene confirmed that the phenotypes were not due to polar effects. A model for mupirocin biosynthesis is presented based on the sequence and biochemical evidence.     

Determination of thorium and uranium at the nanogram per gram level in semiconductor potting plastics by neutron activation analysis

A method was developed to determine thorium and uranium in semiconductor potting plastics. The method is based on neutron activation and subsequent radiochemical separation to isolate and permit measurement of the daughter products²³³Pa and²³⁹Np of the induced²³³Th and²³⁹U. These plastics typically contain macro amounts of silicon, bromine and antimony and nanogram per gram amounts of thorium and uranium. The radiochemical method provides the necessary sensitivity and makes it possible to easily attain adequate decontamination of the tiny amounts of²³³Pa and²³⁹Np from the high levels of radioactive bromine and antimony.Deceased     

Reactions of some fluoroaromatics with the ethoxide anion

The reactions of sodium ethoxide in ethanol with various fluoroaromatics, C₆F_6?nH_n, C₆F_5?nH_nNO₂, C₆F₅X (X = CF₃, C₆F₅, COCH₃, CH₂Br), C₆Cl₆ and $\text{m}$H₂C₆Cl₄ have been studied. Partial substitution of the aromatic halogen was observed. The new products have been characterized by elemental analysis, NMR (H?1 and F?19), infrared and mass spectroscopy.     

Inertial focusing of microparticles,bacteria, and blood in serpentine glass channels

Early detection of pathogenic microorganisms is pivotal to diagnosis and prevention of health and safety crises. Standard methods for pathogen detection often rely on lengthy culturing procedures, confirmed by biochemical assays, leading to >24 h for a diagnosis. The main challenge for pathogen detection is their low concentration within complex matrices. Detection of blood-borne pathogens via techniques such as PCR requires an initial positive blood culture and removal of inhibitory blood components, reducing its potential as a diagnostic tool. Among different label-free microfluidic techniques, inertial focusing on microscale channels holds great promise for automation, parallelization, and passive continuous separation of particles and cells. This work presents inertial microfluidic manipulation of small particles and cells (1–10 μm) in curved serpentine glass channels etched at different depths (deep and shallow designs) that can be exploited for (1) bacteria preconcentration from biological samples and (2) bacteria-blood cell separation. In our shallow device, the ability to focus Escherichia coli into the channel side streams with high recovery (89% at 2.2× preconcentration factor) could be applied for bacteria preconcentration in urine for diagnosis of urinary tract infections. Relying on differential equilibrium positions of red blood cells and E. coli inside the deep device, 97% red blood cells were depleted from 1:50 diluted blood with 54% E. coli recovered at a throughput of 0.7 mL/min. Parallelization of such devices could process relevant volumes of 7 mL whole blood in 10 min, allowing faster sample preparation for downstream molecular diagnostics of bacteria present in bloodstream.