Which emission sources are responsible for the volatile organic compounds in the atmosphere of Pearl River Delta?

A field measurement study of volatile organic compounds (VOCs) was simultaneously carried out in October-December 2007 at an inland Pearl River Delta (PRD) site and a Hong Kong urban site. A receptor model i.e. positive matrix factorization (PMF) was applied to the data for the apportionment of pollution sources in the region. Five and six sources were identified in Hong Kong and the inland PRD region, respectively. The major sources identified in the region were vehicular emissions, solvent use and biomass burning, whereas extra sources found in inland PRD included liquefied petroleum gas and gasoline evaporation. In Hong Kong, the vehicular emissions made the most significant contribution to ambient VOCs (48 ± 4%), followed by solvent use (43 ± 2%) and biomass burning (9 ± 2%). In inland PRD, the largest contributor to ambient VOCs was solvent use (46 ± 1%), and vehicular emissions contributed 26 ± 1% to ambient VOCs. The percentage contribution of vehicular emission in Hong Kong in 2007 is close to that obtained in 2001-2003, whereas in inland PRD the contribution of solvent use to ambient VOCs in 2007 was at the upper range of the results obtained in previous studies and twice the 2006 PRD emission inventory. The findings advance our knowledge of ozone precursors in the PRD region.

Enrichment, isolation and characterization of fungi tolerant to 1-ethyl-3-methylimidazolium acetate

AIMS

  This work aimed to characterize microbial tolerance to 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), an ionic liquid that has emerged as a novel biomass pretreatment for lignocellulosic biomass.

METHODS AND RESULTS

  Enrichment experiments performed using inocula treated with [C2mim][OAc] under solid and liquid cultivation yielded fungal populations dominated by Aspergilli. Ionic liquid-tolerant Aspergillus isolates from these enrichments were capable of growing in a radial plate growth assay in the presence of 10% [C2mim][OAc]. When a [C2mim][OAc]-tolerant Aspergillus fumigatus strain was grown in the presence of switchgrass, endoglucanases and xylanases were secreted that retained residual enzymatic activity in the presence of 20% [C2mim][OAc].

CONCLUSIONS

  The results of the study suggest that tolerance to ionic liquids is a general property of the Aspergilli.

SIGNIFICANCE AND IMPACT OF THE STUDY

  Tolerance to an industrially important ionic liquid was discovered in a fungal genera that is widely used in biotechnology, including biomass deconstruction.

Optimization study of a hybrid alum coagulation-membrane filtration system for virus removal

Due to the intrinsically small sizes of enteric viruses (20-100 nm) and their relatively high resistance to most disinfectants, detection of viruses in treated drinking water is not a rare phenomenon. This study therefore evaluates various aspects involved in a hybrid alum coagulation-ultrafiltration (UF) system for virus removal. Coagulant doses (0, 1 and 10 mg Al(3+)/L) and pH conditions relevant to drinking water (pH 6-8) were investigated. With this hybrid system, removal was not attributable merely to MS2 adsorption to flocs and subsequent retention by UF membranes. MS2 removal comprises of inactivation by the effect of pH and coagulant and subsequently, rejection of virus-associated flocs by UF membrane. Coagulation with 1 mg Al(3+)/L at pH 6 and 7 resulted in an overall reduction brought about by an average of 0.62 log inactivation via the pH effect, 1.2 log inactivation by alum coagulant, and >5.4 log rejection by the 100 kDa polyethersulfone UF membrane. In contrast, negligible upstream inactivation was noted with a coagulant dose of 1 mg Al(3+)/L at pH 8, but 5.8 log rejection was attained with downstream UF filtration. By optimizing the conditions appropriate for upstream inactivation and subsequent membrane rejection, virus removal efficiencies can be enhanced.

Expression and activation of β-adrenoceptors in the colorectal mucosa of rat and human

BACKGROUND

The functions of the distal colon are regulated by local and extrinsic neural pathways. In previous studies, we have found that dopamine (DA) and norepinephrine (NE) could evoke colonic ion transport by activating β-adrenoceptors. The present study aims to investigate the segmental differences in expression and activation of β-adrenoceptors in the distal colon in physiological and pathophysiological conditions.

METHODS

Real-time PCR, immunofluorescence, and Western blotting were used to detect the expression of β-adrenoceptors in the rat and human distal colon. Short-circuit current measurements (Isc) were used to assess the role of β-adrenoceptors in ion transport.

KEY RESULTS

DA and NE caused greater suppression of baseline Isc in distal colon adjacent to the rectum than in segments further away from the anus. These responses were inhibited by selective antagonists of β₁- and β₂-adrenoceptors, but not β₃-adrenoceptor. The expression levels of β₁- and β₂-adrenoceptors in colonic mucosa were higher in colorectum than the regions away from the anus of rats and humans. In wrap-restraint stress (2 h), DA-, NE-induced ΔIsc and the expression of β-adrenoceptors in the colorectum were significantly reduced. However, when endogenous catecholamines were depleted by 6-hydroxydopamine (75 mg kg(-1), i.p., 3 days), DA-, NE-induced ΔIsc as well as the expression of β-adrenoceptors were significantly enhanced in the rat colorectum but not in more proximal regions of the distal colon.

CONCLUSIONS & INFERENCES

β₁- and β₂-adrenoceptors are predominantly expressed in the colorectal mucosa. Perturbation of endogenous catecholamine levels influences the expression and activation of β-adrenoceptors in the colorectal region.

Magnetism and perfect spin filtering effect in graphene nanoflakes

Magnetic and spin-polarized transport properties in zigzag-edged graphene nanoflakes were investigated from first-principles calculations. Ferrimagnetic structure was found to be the ground state for triangular shaped graphene flakes. Magnetism is weakened by doping B or N atoms into the flakes, and it is enhanced if F atoms are doped in certain sublattices of the flakes. The magnetic properties can be rationalized by the behaviors of dopants as well as interactions between dopants and the host atoms. A perfect (100%) spin filtering effect was achieved for the pure or B doped graphene flake sandwiched between two gold electrodes. The orientation of the spin current is found to be flipped if the flake is doped with N, O, or F atoms. The orientation-tunable spin filtering effect is potentially useful in practical applications.

Myocardial infarction and the validation of physician billing and hospitalization data using electronic medical records

OBJECTIVE

Population-based identification of patients with a myocardial infarction is limited to patients presenting to hospital with an acute event. We set out to determine if adding physician billing data to hospital discharge data would result in an accurate capture of patients who have had a myocardial infarction.

METHODS

We performed a retrospective chart abstraction of 969 randomly selected adult patients using data abstracted from primary care physicians on an electronic medical record in Ontario, Canada, as the reference standard.

RESULTS

An algorithm of 3 physician billings in a one-year period with at least one being by a specialist or within a hospital or emergency room plus one hospital discharge abstract performed with a sensitivity of 80.4% (95% CI: 69.5-91.3), specificity of 98.0% (95% CI: 97.1-98.9), positive predictive value of 69.5% (95% CI: 57.7-81.2), negative predictive value of 98.9% (95% CI: 98.2% to 99.6%) and kappa statistic of 0.73 (95% CI: 0.63-0.83).

CONCLUSION

Using a combination of hospital discharge abstracts and physician billing data may be the best way of assessing trends of MI occurrence over time since it increases the capture of MI beyond those patients who have been hospitalized.

Recombinant N-terminal part of bovine herpesvirus 1 ICP27 protein: its preparation, purification, and use for raising specific antiserum

Recombinant N-terminal part of bovine herpesvirus-1 (BoHV-1) ICP27 protein fused with thioredoxin and His-tag ("the recombinant protein") expressed in Escherichia coli was purified by the Ni2+-NTA affinity chromatography and used for the preparation of antiserum by immunization of rabbits. The antiserum recognized the recombinant protein in Western blot analysis and was able to detect BoHV-1 ICP27 in the nucleoli of BoHV-1-infected MDBK cells. These results showed that such an antiserum could serve as a valuable tool in further studies of the functions of BoHV-1 ICP27.

KEYWORDS

Bovine herpesvirus 1, ICP27, recombinant protein, antiserum, immunofluorescence assay.

Suppression effects of AICAR on insulin secretion involved in peroxisome proliferator-activated receptor gamma changes in INS-1 cells

BACKGROUND

AMP-activated protein kinase (AMPK) activation is known to attenuate glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells. However, the underlying mechanisms are poorly understood. The purpose of this study was to examine the effects of AMPK activation on insulin secretion and to determine whether peroxisome proliferator-activated receptors (PPAR) are involved in the effects on INS-1 cells.

METHODS

INS-1 cells, insulinoma cell lines, were treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPAR [MK886 and biphenol A diglycidyl ether (BADGE)] for different treatment times.

RESULTS

AICAR-induced AMPK activation significantly attenuated GSIS as well as insulin content. Meanwhile, AMPK activation increased the mRNA levels of both PPARalpha and PPARgamma. However, with regard to DNA binding, AMPK activation upregulated PPARgamma only, and it was possible to reduce the increment with the AMPK inhibitor. Moreover, the AICAR-induced suppression of insulin secretion can be counteracted by the PPARgamma inhibitor, BADGE but not the PPARalpha inhibitor.

CONCLUSIONS

AICAR-induced glucose-stimulated insulin secretion reduction correlates mainly with PPARgamma changes.

The Effect of Stem Structure on Stress Distribution of a Custom-Made Hip Prosthesis

A custom-made hip is essential for the initial stability and longevity which correspond to an optimal stress distribution, since a standard hip cannot always satisfy every patient's need. In order to find out the designing principles of a custom-made hip, a patient's personal features on which the design was based were acquired. In this study, an integrated finite element model of the hip (including ilium, acetabular cup, femoral head, femoral stem, and femur) was created based on the computed tomography (CT) images of this patient. A series model with different stem length, cross-section, and collodiaphyseal angle were analysed under both static and quasi-static loading conditions. Comparing the stress distribution on each part of the hip prosthesis with that of the natural hip before replacement, the optimal stem structure for this patient was found. In addition, the changes of interspace between acetabular cup and femoral head were measured according to dynamic CT images on the healthy side of this patient during a gait cycle. Results correspond to the trail of the maximum contact stress sites, which were mainly located on the superolateral surface of the acetabular cup. This custom-design method can also be adopted for other patients.