Ultrafine particle generation and measurement

Ultrafine particles (UFPs) with diameters smaller than 100 nm are omnipresent in ambient air. They are important sources for fine particles produced through the agglomeration and/or vapor condensation. With their unique properties, UFPs have also been manufactured for industrial applications. But, from the toxicological and health perspective, ultrafine particles with high surface-to-volume ratios often have high bio-availability and toxicity. Many recent epidemiologic studies have evidence UFPs are highly relevant to human health and disease. In order to better investigate UFPs, better instrumentation and measurement techniques for UFPs are thus in need. The overall objective of this dissertation is to advance out current knowledge on UFPs generation and measurement. Accordingly, it has two major parts: (1) ultrafine particle generation for laboratory aerosol research via electrospray (ES), and (2) ultrafine particle measurement for ambient aerosol monitor and personal exposure study via the development of a cost-effective and compact electrical mobility particle sizer. In the first part, to provide monodisperse nanoparticles, a new single capillary electrospray with a soft X-ray photoionizer as a charge reduction scheme has been developed. The soft X-ray effects on electrospray operation, particle size distribution and particle charge reduction were evaluated. To generate ultrafine particles with sufficient mass concentration for exposure/toxicity study, a TSE twin-head electrospray (THES) was evaluated, as well. The configuration and operational variables of the studied THES has been optimized. Three different nanoparticle suspensions were sprayed to investigate material difference. In the second part, to develop a miniature electrical mobility based ultrafine particle sizer (mini e-UPS), a new mini-plate aerosol charger and a new mini-plate differential mobility analyzer (DMA) have been developed. The performances of mini-plate charger and mini-plate DMA were carefully evaluated for ultrafine particles, including intrinsic/extrinsic charging, extrinsic charge distribution, DMA sizing accuracy and DMA transfer function. A prototype mini e-UPS was then assembled and tested by laboratory generated aerosol. Also a constrained least square method was applied to recover the particle size distribution from the current measured by a mini Faraday Cage aerosol electrometer

Consumer Stated Preference for Acer Laptop from Online Reviews

Consumer preference is a hot topic in the domain of marking management and e-commerce. Many previous studies have been conducted in this field. Whereas, there are rarely studies building on the particular commodity such as laptop. Therefore, this study explores comprehensive features that affect consumer preference for laptops by mining the online reviews. Firstly, we collect 6531 online reviews for Acer laptop from Amazon.cn and code these reviews with Nvivo10. Secondly, we develop a feature-based consumer preference model named MCPL based on the review text analysis. Considering the data imbalance of the collected 6531 product reviews, we adopt a random cluster sampling method to extract 50 groups with 100 samples per group. Then the correspondent regression analyses are conducted for the 50 groups of reviews. Finally, the meta-analysis is creatively conducted to integrate the multiple liner regression results of different groups. According to the result of meta-analysis, we demonstrate dominant features on behalf of the consumer preference of laptop and draw practical implications for enterprise competition strategies to facilitate product design or improvement

Ozonation of trace organic compounds in different municipal and industrial wastewaters : kinetic-based prediction of removal efficiency and ozone dose requirements

For the wide application of ozonation in (industrial and municipal) wastewater treatment, prediction of trace organic compounds (TrOCs) removal and evaluation of energy requirements are essential for its design and operation. In this study, a kinetics approach, based on the correlation between the second order reaction rate constants of TrOCs with ozone and hydroxyl radicals ((OH)-O-center dot) and the ozone and (OH)-O-center dot exposure (i.e., integral (sic)O-3(sic)dt and integral [(OH)-O-center dot]dt, which are defined as the time integral concentration of O-3 and (OH)-O-center dot for a given reaction time), was validated to predict the elimination efficiency in not only municipal wastewaters but also industrial wastewaters. Two municipal wastewater treatment plant effluents from Belgium (HB-effluent) and China (QG-effluent) and two industrial wastewater treatment plant effluents respectively from a China printing and dyeing factory (PD-effluent) and a China lithium-ion battery factory (LZ-effluent) were used for this purpose. The (OH)-O-center dot scavenging rate from the major scavengers (namely alkalinity, effluent organic matter (EfOM) and NO2-) and the total (OH)-O-center dot scavenging rate of each effluent were calculated. The various water matrices and the (OH)-O-center dot scavenging rates resulted in a difference in the requirement for ozone dose and energy for the same level of TrOCs elimination. For example, for more than 90% atrazine (ATZ) abatement in HB-effluent (with a total (OH)-O-center dot scavenging rate of 1.9 x 10(5) s(-1)) the energy requirement was 12.3 x 10(-2) kWh/m(3), which was lower than 30.1 x 10(-2) kWh/m(3) for PD-effluent (with the highest total (OH)-O-center dot scavenging rate of 4.7 x 10(5) s(-1)). Even though the water characteristics of selected wastewater effluents are quite different, the results of measured and predicted TrOCs abatement efficiency demonstrate that the kinetics approach is applicability for the prediction of target TrOCs elimination by ozonation in both municipal and industrial wastewater treatment plant effluents

Traditional Chinese medicine combined with conventional treatment for the patients after percutaneous coronary intervention: A systematic review and meta-analysis

Purpose: To evaluate the efficacy, quality of care and safety of Traditional Chinese Medicine (TCM) after Percutaneous Coronary Intervention (PCI). using systematic review and meta-analysis of randomized controlled trials.Methods: Relevant studies published between January 1st 2010 and August 20th, 2021, on traditional Chinese medicine (TCM) and conventional treatment (CT) after PCI were sourced from different databases including CNKI, CBM, Web of Science, PubMed, Embase and Cochrane library. The TCM was composed of preparations of chinese eaglewood, peppermint, radix notoginseng, scabrous elephant foot herb, Tongxinluo, Danhong, Naoxintong capsule, Huxin Formula and liquorice root while the CT included aspirin (100 mg/day), clopidogrel (75 mg/day), and statins. PRISMA guidelines were used. Primary outcome was to evaluate the efficacy, quality of care and safety of TCM versus conventional treatment post percutaneous coronary intervention (PCI).Results: 110 randomized controlled trials (RCTs) were retrieved and analyzed. The results from metaanalysis showed an enhanced left ventricular ejection fraction (LVEF) % among patients that received TCM compared to those on CT [mean difference ± sd (MD)=5.17, 95% CI (3.29-7.06), Z = 5.38, (P < 0.001)]. Further, hypersensitive C-reactive protein (HS-CRP) level in TCM group was found to be relatively lower than that of the CT group (CG) [MD=-1.44, 95% CI (-2.87-0.00), Z=1.96, (P=0.05)]. In terms of safety, TCM group relative risk score in fixed-effect model was lower than that of the CG [RR=0.66, 95% CI (0.40, 1.10), Z=1.66,].Conclusion: It can be inferred from the results that TCM has more advantages in terms of clinical efficacy, quality of care and safety compared to conventional therapy. However, the lack of substantial research in deploying TCM for the treatment of CHD demands further exploration and strong evidence prior to clinical application of TCM