Search

High time resolution and accuracy are of critical importance in the studies of timing analysis and time delay localization of gamma-ray bursts (GRBs), soft gamma-ray repeaters (SGRs) and pulsars. The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) consisting of two micro-satellites, GECAM-A and GECAM-B, launched on 2020 December 10, is aimed at monitoring and locating X-ray and GRBs all over the sky. To achieve its scientific goals, GECAM is designed to have the highest time resolution (0.1 $\mu {\rm s}$) among all GRB detectors ever flown. Here, we make a comprehensive time calibration campaign including both on-ground and on-orbit tests to derive not only the relative time accuracy of GECAM satellites and detectors, but also the absolute time accuracy of GECAM-B. Using the on-ground calibration with a $\rm ^{22}Na$ radioactive source, we find that the relative time accuracy between GECAM-A and GECAM-B is about 0.15 $\mu {\rm s}$ (1σ). To measure the relative time accuracy between all detectors of a single GECAM satellite, cosmic-ray events detected on orbit are utilized since they could produce many secondary particles simultaneously record by multiple detectors. We find that the relative time accuracy among all detectors onboard GECAM-B is about 0.12 $\mu {\rm s}$ (1σ). Finally, we use the novel Li-CCF method to perform the absolute time calibration with Crab pulsar and SGR J1935+2154, both of which were jointly observed by GECAM-B and Fermi/GBM, and obtain that the time difference between GECAM-B and Fermi/GBM is 3.06 ± 6.04 $\mu {\rm s}$ (1σ).

We present the catalog of Interplanetary Network (IPN) localizations for 199 short-duration gamma-ray bursts (sGRBs) detected by the Konus-Wind (KW) experiment between 2011 January 1 and 2021 August 31, which extends the initial sample of IPN localized KW sGRBs (arXiv:1301.3740) to 495 events. We present the most comprehensive IPN localization data on these events, including probability sky maps in HEALPix format., Published in ApJS

The oxidation of CH2 and SO molecules on Sc— (Sc—C52, Sc—B26N26) and Co-nanocages (Co—C72 and Co—B36N36) are investigated. Results show that the Sc- and Co-nanocages can oxidize the CH2 and SO molecules through Eley—Rideal (ER) and Langmuir—Hinshelwood (LH) mechanisms. Results indicate that in the ER mechanism, intermediates are more stable than those in the LH mechanism by 1.9 kcal/mol. In the LH mechanism, the irretrievable adsorption of OCH2 and SO2 molecules on Sc and Co atoms of Sc—C52, Sc—B26N26, Co—C72, and Co—B36N36 can significantly deactivate the studied catalysts. In the ER mechanism, two OCH2 and two SO2 molecules are created at a normal temperature. Results indicate that in the ER mechanism, barrier energies are lower than those in the LH mechanism by 2.5 kcal/mol. Finally, Sc—C52, Sc—B26N26, Co—C72, and Co—B36N36 are proposed as highly efficient catalysts to oxidize the CH2 and SO molecules.

Fast radio bursts (FRBs) are highly dispersed millisecond-duration radio bursts. Recent observations of a Galactic FRB suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1863 bursts in 82 hr over 54 days from the repeating source FRB~20201124A. These observations show irregular short-time variation of the Faraday rotation measure (RM), which probes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarisation in more than half of the burst sample, including one burst reaching a high fractional circular polarisation of 75%. Oscillations in fractional linear and circular polarisations as well as polarisation angle as a function of wavelength were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetised immediate environment within about an astronomical unit (au; Earth-Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy reveal a barred spiral, with the FRB source residing in a low stellar density, interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova., Comment: 28 pages, 10 figures, updated to match the published version

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne experiment, in operation since 2015, aimed at studying high-energy gamma rays and cosmic nuclei fluxes. Of the various sub-detectors in the DAMPE payload, the Silicon-Tungsten tracKer-converter (STK) plays a significant role in the charge measurement of incoming ions. Depending on the angle of inclination of the impinging particle and its position of impact on these strips, the collected charge can spread between the strips which results in some fractional signal loss. The $\eta$ variable is used to identify this spread of charge across the strips and correct for the associated charge loss. This brings us closer to accurate determination of particle charge which is crucial for ensuring a good discrimination between particles. The $\eta$-correction is, therefore, expected to play an important role in the determination of heavy ions by the DAMPE detector. It has helped reduce the proton background for the helium identification in STK by a factor of 1.5 for MIP tracks. It has been sucessfully applied to carbon nuclei and its application to heavier nuclei is currently being studied.

Since its launch, in December 2015, the satellite-based DAMPE (DArk Matter Particle Explorer) particle detector is taking data smoothly. The Silicon-Tungsten tracKer-converter (STK) of DAMPE consists of six tracking planes (6x, 6y) of single-sided silicon micro-strip detectors mounted on seven support trays. The STK is able to measure the charge and precisely reconstruct the track of traversing charged particles. Tungsten plates (1 mm thick) are integrated in the second, third and fourth tray from the top to serve as $\gamma \rightarrow e^+e^−$ converters. Commissioned rapidly after the launch, the STK is running extremely well since then. The STK in-orbit calibration and performance during its first more than 5 years of operation, including the noise behaviour and the thermal and mechanical stability, are presented in this contribution.

The DArk Matter Particle Explorer (DAMPE) is the first Chinese cosmic-ray direct detection experiment. It has been operating smoothly on-orbit since its successful launch at the end of 2015. Currently, its sub-detectors and the satellite are in good working order. The DAMPE payload employs a BGO Calorimeter for energy measurements, trigger and e/p identification. The calorimeter is constructed of 308 BGO crystals, and PMTs are coupled to the crystals with optical filters to readout scintillation light. In this work, we present the status and performance of the calorimeter, including status of detector units, energy measurement, especially in TeV range, detector endurance, and long term performance in a duration of 65 months.

The Fermi bubbles are two large structures above and below the Galactic Plane. They are first discovered by Fermi-LAT and thought to be related to the jet or the wind from the Galactic center. The DArk Matter Particle Explorer (DAMPE) is a space-borne high energy particle telescope aiming at measuring cosmic rays and photons in a broad energy range. In this work, we use 4.8 years of DAMPE photon data to search for the emission from the Fermi Bubbles. We calculate the TS values of the lobes and the significance of its curved spectrum. The obtained spectral parameters are then compared with those from the Fermi-LAT. We also search for the emission from the cocoon in the southeast part of lobes. Since the Galactic diffuse emission (GDE) model is a major source of systematic uncertainty, we also switch to the GDE models calculated with Galprop and evaluate the influence.

The DArk Matter Particle Explorer (DAMPE), a space-based high energy particle detector, has been operated on-orbit for more than five years. The large geometric factor and good charge resolution enable DAMPE to have very good potential to measure cosmic-rays up to 100 TeV. Knowledge of the boron to carbon (B/C) flux ratio is very important in understanding the prop- agation of cosmic rays, especially in TeV energy range. In this contribution, the latest progress of the B/C flux ratio analysis based on the flight data collected by DAMPE during the 5 years of operation, is presented.

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the DArk Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of $4.3\sigma$. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out., Comment: 11 pages, 13 figures, published in Phys. Rev. Lett. Add one more digit for first three columns in Table S2

The Gravitational Wave highly energetic Electromagnetic Counterpart All-sky Monitor (GECAM) is dedicated to detecting gravitational wave gamma-ray bursts. It is capable of all-sky monitoring over and discovering gamma-ray bursts and new radiation phenomena. GECAM consists of two microsatellites, each equipped with 8 charged particle detectors (CPDs) and 25 gamma-ray detectors (GRDs). The CPD is used to measure charged particles in the space environment, monitor energy and flow intensity changes, and identify between gamma-ray bursts and space charged particle events in conjunction with GRD. CPD uses plastic scintillator as the sensitive material for detection, silicon photomultiplier (SiPM) array as the optically readable device, and the inlaid Am-241 radioactive source as the onboard calibration means. In this paper, we will present the working principle, physical design, functional implementation and preliminary performance test results of the CPD., Comment: accepted to RDTM

To investigate the efficacy and safety of percutaneous coronary intervention in patients with coronary heart disease via radial and femoral artery pathways. Total 122 patients with coronary heart disease who underwent percutaneous coronary intervention in our hospital were selected and divided into observation group (n=61, percutaneous coronary intervention via radial artery) and control group (n=61, percutaneous coronary intervention via femoral artery). The perioperative conditions (operation time, puncture time, postoperative bed rest time and hospital stay) of the two groups were compared. Before and 3 mo after the operation, the heart function indexes [left ventricular ejection fraction, left ventricular end systolic diameter] operation success rate and related complications. There was no significant difference in the stenosis degree of left anterior descending, left circumflex artery, right coronary artery, calcification, angulation and target vessel between the two groups (p>0.05). The puncture time, operation time, postoperative bed time and hospitalization time of the observation group were lower than those of the control group (p 0.05). In addition, 3 mo after operation, left ventricular ejection fraction and left ventricular end systolic diameter in both groups were lower than those before operation (all p

The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) satellite consists of two small satellites. Each GECAM payload contains 25 gamma ray detectors (GRD) and 8 charged particle detectors (CPD). GRD is the main detector which can detect gamma-rays and particles and localize the Gamma-Ray Bursts (GRB),while CPD is used to help GRD to discriminate gamma-ray bursts and charged particle bursts. The GRD makes use of lanthanum bromide (LaBr3) crystal readout by SiPM. As the all available SiPM devices belong to commercial grade, quality assurance tests need to be performed in accordance with the aerospace specifications. In this paper, we present the results of quality assurance tests, especially a detailed mechanism analysis of failed devices during the development of GECAM. This paper also summarizes the application experience of commercial-grade SiPM devices in aerospace payloads, and provides suggestions for forthcoming SiPM space applications., Comment: 13 pages, 23 figures

Background: Each GECAM satellite payload contains 25 gamma-ray detectors (GRDs), which can detect gamma-rays and particles and can roughly localize the Gamma-Ray Bursts (GRBs). GRD was designed using lanthanum bromide (LaBr3) crystal as the sensitive material with the rear end coupled with silicon photomultiplier (SiPM) array for readout. Purpose: In aerospace engineering design of GRD, there are many key points to be studied. In this paper, we present the specific design scheme of GRD, the assembly and the performance test results of detectors. Methods: Based on Monte Carlo simulation and experimental test results, the specific schematic design and assembling process ofGRDwere optimized. After being fully assembled, theGRDswere conducted performance tests by using radioactive source and also conducted random vibration tests. Result and conclusion: The test results show that all satellite-borne GRDs have energy resolution, 10 pages, 15 figures

Mycotoxins are the secondary metabolites of fungi, especially moulds. They have over 300 types and can be easily produced ubiquitously by moulds. Many mycotoxins have been found to be toxic to most farmed animals through the diets. With the globalization of feed ingredient trade and the rapid climate changes, occurrence of mycotoxins become increasingly difficult to be predicted. Thus, the unnoticeable mycotoxin hazards can directly impact the animal production systems. Preventing or minimizing mycotoxins in feed ingredients has become an important topic from the aspect of feed manufacturing industry. The aim of this literature review is to summarize the effective strategies for feed manufacturers to minimize the mycotoxin hazards. Prevention methods, including pre-harvest field management and post-harvest storage management, are still the most effective strategies, since mycotoxins are hardly to be eliminated once they are present in the ingredients. Moreover, mycotoxin reducing effects of several feed manufacturing technologies are also reviewed. In this review, the mycotoxin reducing methods are mainly categorized into 4 methodologies: physical methods, thermal methods, chemical methods, and mycotoxin controlling feed additives. The first three methodologies mainly focus on how to reduce mycotoxins in feed ingredients during processes, while the last one on how to compensate the adverse impacts of mycotoxin-contaminated diets in animal bodies. The results showed that most of the methods reviewed show evident mycotoxin reducing effects, but of different consistencies. On the other hand, many practical factors that can affect the feasibility of each method in practical manufacturing are also discussed in this review. In conclusion, mycotoxin prevention management and the processing stage of cleaning and sorting are still the most efficient strategies to control mycotoxin hazards in current feed manufacturing.

DAMPE satellite has directly measured the cosmic ray proton spectrum from 40 GeV to 100 TeV and revealed a new feature at about 13.6 TeV., The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

The China Seismo-Electromagnetic Satellite (CSES) aims to monitor space electromagnetic fields, ionospheric plasma, high-energy charged particles and other features of the global space environment. The high-energy particle package (HEPP), which can effectively detect the energy spectrum, flux and pitch angle distribution of space electrons and protons, and soft X-ray emission from solar flares, is one of the main payloads of CSES. In this study, we designed, developed and calibrated the high-energy particle package and launched it into orbit with CSES. HEPP consists of the high-energy detector (HEPP-H), the low-energy detector (HEPP-L), and the solar X-ray monitor (HEPP-X). The three sub-detectors mainly use silicon detector and crystal calorimeter detection technology. Before launching, we calibrated the three sub-detectors in detail by using radiation source and accelerator beam. All the three sub-detectors have good energy linearity. After launching into orbit, the space energetic particles and X-ray distribution detected by HEPP are consistent with expectations. The performance indices of the detector reach the advanced level of the same kind of detector in the world. HEPP has a wide energy detection range, good energy resolution and high angular resolution ability for electrons and protons. It will play an important role in the study of space particle response and space physics of seismic activity.

The DArk Matter Particle Explorer (DAMPE), a satellite-based cosmic ray and gamma-ray detector, was launched on December 17, 2015, and began its on-orbit operation on December 24, 2015. In this work we document the on-orbit calibration procedures used by DAMPE and report the calibration results of the Plastic Scintillator strip Detector (PSD), the Silicon-Tungsten tracKer-converter (STK), the BGO imaging calorimeter (BGO), and the Neutron Detector (NUD). The results are obtained using Galactic cosmic rays, bright known GeV gamma-ray sources, and charge injection into the front-end electronics of each sub-detector. The determination of the boundary of the South Atlantic Anomaly (SAA), the measurement of the live time, and the alignments of the detectors are also introduced. The calibration results demonstrate the stability of the detectors in almost two years of the on-orbit operation.

Alzheimer's disease (AD) is characterized by the accumulation and deposition of plaques of amyloid-β (Aβ) peptide in the brain. Growing epidemiological and experimental studies have shown that 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) exerts neuroprotection against AD. However, the underlying mechanisms of the action remain unclear. Since Aβ clearance plays a crucial role in Aβ balance in the brain, the aim of the present study was to investigate potential effects of 1,25(OH)2D3 on Aβ1-40, the major soluble oligomeric form of Aβ, clearance via transport across blood-brain barrier (BBB) mediated by low-density lipoprotein receptor-related protein 1 (LRP1) (efflux) and receptor for advanced glycation end products (RAGE) (influx) and peripheral uptake by liver mediated by LRP1. We identified colocalization of LRP1 and RAGE at BBB of mice, established an in vitro BBB model by culturing monolayer mouse brain microvascular endothelial cell line (bEnd.3) cells under hypoxia and observed that 1,25(OH)2D3 treatment enhanced Aβ1-40 efflux across the BBB model and uptake by HepG2 cells. After 1,25(OH)2D3 exposure, LRP1 expression was increased significantly both in vivo and in vitro, and RAGE expression was reduced in the in vitro BBB model but not in microvascular endothelial cells of mice hippocampus. Additionally, we explored the correlation between the corresponding effects of 1,25(OH)2D3 and its nuclear hormone receptor vitamin D receptor (VDR) level. We found that VDR expression was upregulated after 1,25(OH)2D3 treatment both in vivo and in vitro. Collectively, our finding that 1,25(OH)2D3 reduces cerebral Aβ1-40 level by increasing Aβ1-40 brain-to-blood efflux and peripheral uptake through regulating LRP1 and RAGE could shed light on the mechanism of 1,25(OH)2D3 neuroprotection against AD. And the action of 1,25(OH)2D3 might be associated with the VDR pathway.

The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives include the study of galactic cosmic rays up to $\sim 10$ TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the search for dark matter signatures in their spectra. In this paper we illustrate the layout of the DAMPE instrument, and discuss the results of beam tests and calibrations performed on ground. Finally we present the expected performance in space and give an overview of the mission key scientific goals., 45 pages, including 29 figures and 6 tables. Published in Astropart. Phys

High energy cosmic ray electrons plus positrons (CREs), which lose energy quickly during their propagation, provide an ideal probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been directly measured up to $\sim 2$ TeV in previous balloon- or space-borne experiments, and indirectly up to $\sim 5$ TeV by ground-based Cherenkov $\gamma$-ray telescope arrays. Evidence for a spectral break in the TeV energy range has been provided by indirect measurements of H.E.S.S., although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range $25~{\rm GeV}-4.6~{\rm TeV}$ by the DArk Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The majority of the spectrum can be properly fitted by a smoothly broken power-law model rather than a single power-law model. The direct detection of a spectral break at $E \sim0.9$ TeV confirms the evidence found by H.E.S.S., clarifies the behavior of the CRE spectrum at energies above 1 TeV and sheds light on the physical origin of the sub-TeV CREs., Comment: 18 pages, 6 figures, Nature in press, doi:10.1038/nature24475

We present the primary observations of the Solar X-ray Monitor (SXM) payload onboard the ChangE-1 lunar exploration satellite, which was launched on 24 October 2007. The SXM payload uses a solid-state silicon P-I-N photo-diode (Si-PIN) whose dynamic energy ranges from 1 keV to 10 keV. The long-term integrated spectra at different solar-activity levels as observed by the SXM are presented. By fitting these spectra with an optically thin plasma model, the two-minute temperature variation of the solar coronal plasma during a solar flare is also presented.

SummaryThe effects of the ice nucleation-active (INA) bacterium Pseudomonas syringae were studied on the physiological response and ultrastructure of the floral organs of ‘Longwangmao’ apricot (Prunus armeniaca Linn.). Inoculation with INA bacteria increased the super-cooling point (SCP) of petals, stamens, and pistils by 2.1oC, 1.6oC, and 1.4oC respectively. INA bacteria also enhanced the relative electrolyte leakage (REL) of membranes in the floral organs, indicating that INA bacteria increased the permeability of membranes. INA bacteria enabled apricot floral organs to maintain relatively lower superoxide dismutase (SOD) and peroxidase (POD) activities, and led to an accumulation of malonyldialdehyde (MDA) under cold stress. The ultrastructures of pollen walls, organelles in the pollen cell, ovules and egg cells in control flowers which were subjected to –3oC changed slightly, compared with the structures at 18oC. However, under cold stress at –3oC, inoculation with INA bacteria resulted in disintegrat...

It is well-known that aromatic molecules, when irradiated by UV laser beams in the nanosecond pulse width regime, yield exclusive parent ions at laser intensities of 107 W cm-2 (soft ionization). As the laser intensities increase up to 109 W cm-2, however, extensive fragmentation takes place such that small mass fragments dominate the spectra at the expense of parent signature ions. The reason for this is that the dissociative lifetimes are shorter than the laser pulse width and ladder-switching fragmentation takes place. With the development of high power femtosecond lasers, these dissociative lifetimes can often be bypassed. Presently, at laser intensities up to the order of 1015 W cm-2 with pulse widths as short as 50 fs at near-infrared (IR) wavelengths (790 nm), soft ionization again takes place. This has been seen using a technique known as femtosecond laser mass spectrometry (FLMS). Under such conditions, stable multiply charged parent and adjacent satellite ions are observed and the fragmentation ...

In a recent series of experiments, femtosecond laser mass spectrometry (FLMS) was applied to benzaldehyde utilizing laser pulse widths in the range 90 fs to 2.7 ps. Beam intensities up to 2 × 1014 ...

Urban air quality is of considerable importance in many cities throughout Europe and the USA. In particular, current EU legislation has driven an expansion of monitoring of more pollutants at more sites. At present in the UK, real time readings are now available for benzene, buta-1,3-diene and other volatile organic compounds, airborne fine dust (PM10), CO, O3, SO2 and NOx. Carbon monoxide is produced to varying degrees in all combustion processes but more than 90% is caused by emissions from petrol vehicle exhausts. The World Health Organisation guidelines for exposure to the gas is

Mitiglinide (MGN) is a new insulinotropic agent of the glinide class with rapid onset. The effects of food intake on the pharmacokinetic (PK) profile of mitiglinide tablets after single oral administration have not yet been reported in healthy adults. We aimed to assess the effects of food intake on the PK properties of mitiglinide (MGN) tablets, using a novel analytical method, after single escalating oral doses in healthy Chinese volunteers.In this open-label, randomized, single-dose (three distinct doses), two-way crossover PK study, three doses of MGN 5, 10 or 20 mg were administered to healthy adult volunteers after an overnight fast (fasted condition) or low-fat breakfast (fed condition) (period 1). After 7 days, the participants received the same dose under the opposite fed/fasted condition (period 2). Serial blood samples were obtained before and through 8 h after study drug administration. Concentrations of MGN in plasma were determined using UPLC-MS/MS. Adverse events (AEs) were monitored and recorded on each in-clinic day.Twenty-four Chinese volunteers (eight [four men, four women] volunteers per group) were enrolled in the study. The extent of absorption of MGN was similar in both fed and fasted conditions at single doses in the range 5-20 mg. Food intake was associated with decreases in C(max) by 60·4% to 65·2% in the three dose groups and greatly delayed T(max) [0·36(Standard deviation 0·16) vs. 1·75(0·92) hours with 5 mg, 0·29(0·19) vs. 1·97(0·81) hours with 10 mg and 0·30(0·10) vs. 1·18(0·68) hours with 20 mg; all, P0·05]. t(1/2) , CL/F and V/F (P0·05) were unaffected. MRT(0-8) at the 5 and 10-mg doses, but not at the 20-mg dose, were markedly lower in fasted volunteers than fed volunteers (P0·05).Using a novel UPLC-MS/MS method, we showed that food intake affected the rate but not the extent of absorption of MGN within the 5- to 20-mg dose range. Gender did not appear to affect the PK properties of MGN in either fasted or fed states. MGN should be preferably taken before food.

A solid-phase extraction-liquid chromatographic-tandem mass spectrometry method for the determination of nalbuphine concentrations in human plasma has been developed. Samples (1 mL) were extracted using a Strata™-X solid phase extraction cartridges. Chromatographic separation of nalbuphine and naloxone (internal standard) was achieved on a Phenomenex Kinetex PFP (2.6 μm, 100 A, 100 × 2.1 mm) column using a mobile phase consisting of 0.1% formic acid, 15 mM ammonium acetate in deionized water and acetonitrile (60:40, v/v). The flow rate was 0.3 mL/min and the total run time was 2 min. Detection of the analytes was achieved using positive ion electrospray ionization via multiple reactions monitoring mode. The mass transitions were m/z 358 → 340 for nalbuphine and m/z 328 → 310 for naloxone. The assay was linear over the concentration range 0.50-500.00 ng/mL, with correlation coefficients ≥0.995. The lower limit of quantitation was set at 0.5 ng/mL plasma based on an average signal-to-noise ratio of 44.79. The intra- and inter-day precision was less than 8.07% in terms of relative standard deviation and accuracy ranged from 94.97 to 106.29% at all quality control levels. The method was applied successfully to determine nalbuphine concentrations in human plasma samples obtained from subjects receiving intravenous administration of nalbuphine. The method is rapid, sensitive, selective and directly applicable to human pharmacokinetic studies involving nalbuphine.

A new generalization of the negative binomial distribution (GNBD) is introduced and fitted to counts of Oncomelania hupensis, the intermediate host of Schistosoma japonicum, made, in areas of Chinese lakeland and marshland, early in the winter of 2005 and late in the spring of 2006. The GNBD was found to fit the snail data better than the standard negative binomial distribution (NBD) that has previously been widely used to model the distribution of O. hupensis. With two more parameters than the NBD, the GNBD can integrate many discrete distributions and is more flexible than the NBD in modelling O. hupensis. It also provides a better theoretical distribution for the quantitative study of O. hupensis, especially in building an accurate prediction model of snail density. The justification for adopting the GNBD is discussed. The GNBD allows researchers to broaden the field in the quantitative study not only of O. hupensis and schistosomiasis japonica but also of other environment-related helminthiases and family-clustered diseases that have, traditionally, been modelled using the NBD.

We recently showed that the peritoneal surface layer may be an important barrier in modulating peritoneal membrane permeability. In the present study, we investigated the relationship between an increased peritoneal transport rate and the peritoneal surface layer.Male Sprague-Dawley rats (n = 8) received intraperitoneal injections of 4.25% glucose dialysate daily for 1 week. Forty-eight hours after the last injection, a 4-hour dwell study using 25 mL 4.25% glucose dialysate was performed in each rat. The results were compared with those from control rats that received no intraperitoneal injections (n = 8). The peritoneal fluid and small-solute transport characteristics were evaluated. The peritoneal surface layer was studied using an electron microscope. The phospholipids content of the dialysate was also evaluated.Peritoneal fluid removal was significantly reduced in the daily injection group (30.6 +/- 1.3 mL) as compared with the control group (38.2 +/- 0.6 mL). The peritoneal fluid absorption rate and small-solute transport rate were also significantly higher in the daily injection group as compared with the control group. The amounts of phospholipids in the dialysate were significantly lower in the daily injection group--especially the quantity of phosphatidylcholine. However, lysophosphatidylcholine increased significantly in the daily injection group. Electron microscopy showed that the peritoneal surface layer was almost completely gone in the daily injection group, but that a dense and thick (average 4 microm) peritoneal surface layer was present on the top of the mesothelial cells in the control group.Our results suggest that daily injection of hypertonic glucose dialysate significantly increased the peritoneal transport rate. The increased peritoneal transport rate was associated with a significant reduction in the peritoneal surface layer and the phospholipids content of the dialysis effluent.

Anemia is common in dialysis patients. Change in phospholipids asymmetry in red blood cells (RBCs) may affect the removal of RBCs from the circulation and thus shorten the lifespan of RBCs. In the present study, we investigated phospholipids asymmetry in RBCs in uremic patients and its relationship with anemia. We studied 34 continuous ambulatory peritoneal dialysis (CAPD) patients (age: 51 +/- 15 years), 73 hemodialysis (HD) patients (age: 48 +/- 12 years), 8 pre-dialysis renal-failure patients (age: 42 +/- 21 years), and 16 healthy controls (age: 32 +/- 9 years). All patients were clinically stable. Phospholipids asymmetry as measured by phosphatidylserine exposure was determined by a flow-cytometric annexin V-binding assay. Hemoglobin levels were 93 +/- 20 g/L, 83 +/- 17 g/L, 78 +/- 21 g/L, and 145.8 +/- 12.5 g/L for CAPD patients, pre-dialysis patients, HD patients, and healthy controls respectively. Phosphatidylserine exposure in RBCs was significantly higher in uremic patients as compared with healthy controls, especially in HD patients--whose values were significantly higher than values seen in CAPD patients and pre-dialysis patients. No significant difference was seen in RBC phosphatidylserine exposure between pre-dialysis patients and CAPD patients. Cells positive for annexin V binding were 1.58%, 1.40%, 2.11%, and 0.71% for CAPD patients, pre-dialysis patients, HD patients, and healthy controls respectively. Significant reverse correlations were seen between annexin V and hemoglobin (r = -0.381, p0.001), and between annexin V and hematocrit (r = -0.355, p0.001). Our results suggest that (1) anemia is common in our uremic patients, especially in HD patients; and (2) anemia in uremic patients may be partly related to the loss of phospholipids asymmetry in RBCs.

We have shown that intraperitoneal (i.p.) addition of hyaluronan (HA) in a single dwell study in rat could increase peritoneal fluid removal by decreasing the peritoneal fluid absorption rate. In this study, we investigated the impact of repeated use of HA on peritoneal membrane transport characteristics.Twelve male Sprague-Dawley rats received a once-daily i.p. injection of 25 mL 4.25% glucose dialysis solution without (HP group, n = 6) or with 0.025% HA (HA group, n = 6) for 1 week. Forty-eight hours after the last injection, a 4-hour dwell using 25 mL 4.25% glucose dialysis solution with i.p. volume marker and frequent dialysate and blood samplings was performed in each rat as well as in rats that did not receive any injection (control group, n = 8).Although the i.p. volumes were significantly lower in the HP and HA groups compared to the control group, i.p. volume in the HA group was significantly higher than in the HP group. Net ultrafiltration at 4 hours was 5.6 +/- 1.3 mL, 10.2 +/- 1.8 mL, and 13.2 +/- 0.6 mL for the HP, HA, and control group, respectively. The peritoneal fluid absorption rate decreased by 45% in the HA group compared to the HP group. There was no significant difference in peritoneal fluid absorption rate between the HA and the control group. No difference was found in the direct lymphatic absorption rate between the HP and HA groups [0.010 +/- 0.003 mL/minute in the HP group and 0.011 +/- 0.004 mL/min in the HA group] although they were both higher than that of the control group (0.004 +/- 0.001 mL/min). The solute transport rates were in general significantly higher in the HP group compared to the HA and control groups, and there was no significant difference between the latter two groups, except that protein transport rate was significantly lower in the HA group compared to the control group.The present study suggests that (1) repeated exposure to hypertonic glucose-based dialysis solution results in increased peritoneal solute transport rates, as well as increased peritoneal fluid absorption rates; and (2) these changes, reflecting a highly permeable peritoneal membrane, were ameliorated by repeated i.p. addition of hyaluronan. The similar changes in the direct lymphatic absorption rate in rats that received daily i.p. injection of dialysis solution suggest that direct peritoneal lymphatic absorption was not influenced by hyaluronan.

In the present Letter we report that a number of polyatomic molecules (M) when irradiated with short pulse lasers

A RP-HPLC method was developed to determine the concentrations of sinomenine HCl in serum and urine and its pharmacokinetics was studied in healthy volunteers. C18H37 column was eluted with the mobile phase of acetonitrile--0.01 mol.L-1 sodium phosphate monobasic--N, N, N', N'-tetramethylenediamine (46:54:0.22 v/v, pH 6.9) and the ultraviolet absorbance was monitored at 263 nm. Triazolan was used as internal standard. The calibration curves were linear in the range of 6-480 ng.ml-1 in serum and 0.06-3 micrograms.ml-1 in urine, with mean recoveries of 75.46% and 91.38% respectively. The lowest detectable limits were 4 ng.ml-1 in serum and 40 ng.ml-1 in urine and the RSD for the intra-day and inter-day were less than 5%. A single oral dose of 80 mg sinomenine HCl tablet was given to 8 healthy male volunteers. The concentrations of sinomenine HCl in serum and urine were determined. The serum concentration--time curve was found to fit a two-compartment open model with first order elimination. The pharmacokinetic parameters were: T1/2 alpha 0.791 +/- 0.491 h, T1/2 beta 9.397 +/- 2.425 h, Tmax 1.040 +/- 0.274 h, Cmax 246.604 +/- 71.165 ng.ml-1, AUC 2651.158 +/- 1039.050 ng.h.ml-1, CL 0.033 +/- 0.010 ng.ml-1.

Underground coal fires in China cause serious environmental problems, in addition to the loss of valuable coal resources. The present study aims at developing a quick and practical method to estimate the depth of coal fires using data integration techniques. In coal fields which have underground coal fires, the subsurface fires are associated with surface thermal anomalies. Airborne thermal infrared scanner data and colour infrared photographs were used in this study to depict the coal fire front and the outcrop of coal seams, respectively. A Digital Elevation Model (DEM) of the study area was produced from topographic maps at 1:25 000 scale. Finally, taking into account the spreading direction of the coal fires and the relationships between thermal anomalies, relief factors and the occurrence of coal seams, the depths of the coal fires were obtained automatically by means of integration of remote sensing data and GIS techniques. This helped to target the fire fighting operations and made them more cost effective.

A laser based procedure, which combines the REMPI technique and ion chamber detection to give a very high sensitivity, has been developed at Glasgow to detect urban air pollutants NOx(x=1,2) and CO. Several REMPI schemes have been tested for CO monitoring. Among them, the (2+1) process at 230 nm, i.e. the two photon transition B1Σ+←X1Σ+(0,0) and one photon ionisation is the best one for trace detection. A sensitivity of 0.6 ppm is reached by this procedure which is far below the standard recommended by the authorised UK expert panel: 10 ppm Street air samples have been measured and compared with standard gas samples. The results showed that the CO concentration in the air at rush hour in Glasgow is about 2.5 ppm. This value is in accordance with the data announced by the British Atmospheric Data Centre which says the CO concentration in Glasgow is 3 ppm. Other measurements, e.g. laser power dependence of CO ion yields, are also included in this paper.

It has been known for some time that the presence of NO plays an important part in the degradation of organic pollutants and in the formation of ozone and nitric acid in the troposphere. In recent years. there has been a significant increase in the concentration of atmospheric NO and aconsequent decrease in air quality. The authors believe that there is now a need for a computer- controlled, near-real time monitoring system for atmospheric gas samples taken from a large urbanarea. This paper describes a laser-based REMPI procedure which utilises a high power pulsed laser,atmospheric pressure ionisation chamber and data acquisition system and. with a detection limits aslow as I ppb. it may well form the basis of such a system. 1 INTRODUCTION Public interest in the quality of air is certainly not new - the citizens of ancient Rome frequentlycomplained to Senate regarding the indigenous aromas within the city! More recently. in the 1950s and1960s. many industrialised countries were subjected to severe winter smogs (smoke +fog) with theirassociated health hazards to the public and, as a result. legislation was introduced in Europe and theUSA. For example, the UK Clean Air Acts of 1956 and 1968 were designed to combat the emission ofparticulate and gaseous effluents due to the widespread combustion of coal. The visible impact of this

It has been known for some time that the combustion of fossil fuels, biomass burning and the automobile, have principally lead to the increased presence of NOX (x=1,2) in the atmosphere especially in the urban environment. The average concentrations of NOX in American, European cities and specifically in Glasgow is about 35 ppb. A laser based procedure, using ionization chambers, has been developed, which will detect NO down to sub ppb levels and NO2 to a few parts per billion. A number of wavelengths can be used but a three photon process at 380 nm is likely to be the most sensitive and selective wavelength for this analysis. This procedure can also be used for a number of other urban pollutants with a single laser operating in the range 200–400 nm.

Urban air quality is at present a matter of considerable importance in many cities throughout Europe and the USA. The combustion of fossil fuels and, in particular, automobile emissions have lead to the increase of NOx(x= 1,2) in the urban environment. The average concentrations of NOx in the atmosphere vary considerably from city to city in America and Europe. They are also a function of weather conditions and time of day but an EC (now EU) directive suggests that they should not exceed 135 µg m–3(72 ppb by volume). Many other urban pollutants are also required to be measured and current legislation is forcing scientists to develop better detection techniques which can be applied to monitoring a number of different pollutants with the same instrumentation. To this end, a laser-based procedure, using simple ionization chambers, has been developed in Glasgow which will detect NO in N2 down to sub-parts per billion levels and NO2 in air to a few parts per billion. A number of different laser wavelengths can be used but a two-photon process at 226 nm or a three-photon process at 384 nm are likely to be the most sensitive and selective wavelengths for this purpose. This procedure can also be used for a number of other urban pollutants using a single laser operating in the wavelength range 200–400 nm.

Nitrobenzene and o-nitrotoluene were detected in trace concentrations in gas mixtures at atmospheric pressure in a simple unity-gain ionization chamber. The detection procedure relies on tunable ultraviolet laser radiation that identifies the characteristic wavelength dependence of the NO+ ion fragment. Sensitivity levels are 0.25 ± 0.05 ppm for nitrobenzene and 0.75 ± 0.1 ppm for o-nitrotoluene, with the current limitations being background ionization, laser power and small sampling volume. Additionally, nominally 1 ppm NO and NO2 gas samples were analysed and the saturation fluence (via a resonant two-photon process at 226.3 nm) for NO+ production from NO gas was determined. Sensitivity levels of 120 and 50 ppb were estimated from the data on NO2 and NO, respectively. It is shown that an increase in sensitivity of an order of magnitude is possible in all instances if the experimental parameters are optimized.

Using laser spectroscopic techniques the natural radiative lifetimes of 4s2n1s2S and 4s2n2d2D states of neutral gallium have been measured forn1 = 6 to 11 andn2 = 4 to 9. These states, as well as previously measured4s2np2P states, have been investigated theoretically using multi-configuration Hartree-Fock calculations. Oscillator strengths to all lower-lying states have been calculated and theoretical lifetimes of the investigated states evaluated. The2D sequence is strongly influenced by the 4s4p22D perturber, and strong cancellation effects in the radiative decay are observed both theoretically and experimentally.