Microfluidic in-line dynamic light scattering with a commercial fibre optic system.

We report the coupling of dynamic light scattering (DLS) in microfluidics, using a contact-free fibre-optic system, enabling the under-flow characterisation of a range of solutions, dispersions, and structured fluids. The system is evaluated and validated with model systems, specifically micellar and (dilute) polymer solutions, and colloidal dispersions of different radii (∼1-100 nm). A systematic method of flow-DLS analysis is examined as a function of flow velocity (0-16 cm s-1), and considerations of the relative contribution of 'transit' and 'Brownian' terms enable the identification of regions where (i) a quiescent approximation suffices, (ii) the flow-DLS framework holds, as well as (iii) where deviations are found, until eventually (iv) the convection dominates. We investigate practically relevant, robust setups, namely that of a capillary connected to microdevice, as well as direct measurement on a glass microdevice, examining the role of capillary dimensions and challenges of optical alignment. We conclude with a demonstration of a continuous flow measurement of a binary surfactant/salt solution, whose micellar dimensions vary with composition, characterised with hundreds of data points (every ∼5 s) and adequate statistics, within a few minutes.

The methodological quality of surgical randomized controlled trials: A cross-sectional systemic review.

Systematic reviews of RCTs have been developed to address end-users' needs and are regarded as the highest level of evidence. Flaws in the design, conduct and analyses of a systematic review can lead to erroneous conclusions and increase the research waste. We undertook a cross-sectional survey to identify the critical areas of weakness in systematic reviews for surgical interventions by AMSTAR 2. We searched PubMed, EMbase and Cochrane Library to summarize systematic reviews of surgical RCTs published in 2017. The information regarding general characteristics and methodological characteristics were gathered. We conducted descriptive analyses of study characteristics of included systematic reviews and explored the difference among varied methodological quality. Totally 141 systematic reviews were identified. We found only four reviews (2.8%) were high quality, 3 (2.1%) were moderate quality, 8 (5.7%) were low quality, and the remaining 126 (89.4%) were of critical low quality. The critical weaknesses were lack of pre-registration or published protocols (29.1%), comprehensive literature search (17.7%), lists of excluded studies and reasons for exclusion (19.1%), description of detailed interventions (8.5%), extraction of funding source from included trials (10.6%), and consideration of the risk of bias of included trials when synthesized (16.3%) and interpret (20.6%) the results. Higher methodological quality was only positively associated with Cochrane systematic review. Although two-thirds of included systematic reviews in the field of surgery were published in journals ranking Q1, the methodological quality is suboptimal and needs to be substantially improved. More efforts of multi-disciplinary teams' collaboration, continual education and training, integrally connection between primary studies and systematic review and contributing surgical research to practice should be imperative.

Characteristics and ozone formation potential of volatile organic compounds in emissions from a typical Chinese coking plant.

Coking industry is an important volatile organic compounds (VOCs) emission source in China, however, detailed information on VOCs emissions is lacking. Therefore, we selected a typical mechanized coking plant and collected air samples according to the Emission Standard of Pollutants for Coking Chemical Industry (GB16171-2012). Using gas chromatography-mass spectrometry method, we analyzed the VOCs in the air samples, and applied maximum increment reactivity (MIR) rule to estimate ozone formation potential (OFP) of the VOCs emitted from the coke production. More than 90 VOCs species were detected from the coking plant, including alkanes, alkenes, alkynes, aromatic hydrocarbons, halogenated hydrocarbons and oxygenated VOCs. The concentrations of VOCs (ρ(VOCs)) generated at different stages of the coking process are significantly different. ρ(VOCs) from coke oven chimney had the highest concentration (87.1 mg/m3), followed by coke pushing (4.0 mg/m3), coal charging (3.3 mg/m3) and coke oven tops (1.1 mg/m3). VOCs species emitted from the coke production processes were dominated by alkanes and alkenes, but the composition proportions were different at the different stages. Alkenes were the most abundant emission species in flue gases of the coke oven chimney accounting for up to 66% of the total VOCs, while the VOCs emissions from coke pushing and coal charging were dominated by alkanes (36% and 42%, respectively), and the alkanes and alkenes emitted from coke oven top were similar (31% and 29%, respectively). Based on above results, reduction of VOCs emissions from coke oven chimney flue gases is suggested to be an effective measure, especially for alkenes.