Learn More
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining four tobacco-specific N-nitrosamines (TSNAs) in mainstream smoke from Chinese Virginia cigarettes was developed. Mainstream cigarette smoke particulate matter was collected on a Cambridge filter pad, further extracted using 100 mM ammonium acetate after 100 microL internal(More)
A simple and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-ESI-MS-MS) method was developed and validated for the quantification of creatinine in human urine. The analysis was carried out on an Agilent Zorbax Eclipse XDB-C18 column (2.1 × 150 mm, 3.5 μm). The mobile phase was 0.1% formic acid in water and 0.1% formic acid in(More)
Heavy metals in tobacco caused wide public concern. To study the impact of heavy metals in smokers, 193 smokers and 58 nonsmokers were surveyed, and their urinary levels of chromium (UCr), lead (UPb), and cadmium (UCd) were assayed. In this study, UCr, UPb, and UCd in smokers (33.41 ± 14.99, 3.21 ± 1.34, 0.38 ± 0.64 μg/24 h, respectively) and nonsmokers(More)
N-nitrosonornicotine (NNN), 4-( methylnitrosamino )-1-(3-pyridyl )-1-butanone (NNK), N-nitrosoanatabine (NAT) and N-nitrosoanabasine (NAB) are the most abundant carcinogens identified in tobacco and tobacco smoke. The accurate quantifications of NNN, NNK, NAT and NAB are necessary to evaluate its impact on the public health. A liquid(More)
A method was developed for the simultaneous extraction and determination of four mercapturic acids (MAs), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (3-HPMA), N-acetyl-S-(2-carboxyethyl)-L-cysteine ( CEMA) and S-phenylmercapturic acid (SPMA), in human urine using solid phase extraction and high performance(More)
The transcription regulator PbrR691, one of the MerR family proteins, shows extremely high sensitivity and selectivity toward Pb(II) in Ralstonia metallidurans CH34. Here, we present the crystal structure of PbrR691 in complex with Pb(II) at 2.0 Å resolution. The Pb(II) coordinates with three conserved cysteines and adopts a unique trigonal-pyramidal(More)
The metalloprotein MerR is a mercury(II)-dependent transcriptional repressor-activator that responds to mercury(II) with extraordinary sensitivity and selectivity. It's widely distributed in both Gram-negative and Gram-positive bacteria but with barely detectable sequence identities between the two sources. To provide structural basis for the considerable(More)
Application relays can be used to reduce latency for real-time media communication. In this paper, we utilize the triangle inequality violations (TIV) in delay space to model the relays and analyze their properties in several data sets. We find that both the demand and utility for relays approximate the power law distribution, which inspires us to deduce(More)