The effect of dynamic operating conditions on nano-particle emissions from a light-duty diesel engine applicable to prime and auxiliary machines on marine vessels

ABSTRACTThis study presents the nano-sized particle emission characteristics from a small turbocharged common rail diesel engine applicable to prime and auxiliary machines on marine vessels. The experiments were conducted under dynamic engine operating conditions, such as steady-state, cold start, and transient conditions. The particle number and size distributions were analyzed with a high resolution PM analyzer. The diesel oxidation catalyst (DOC) had an insignificant effect on the reduction in particle number, but particle number emissions were drastically reduced by 3 to 4 orders of magnitude downstream of the diesel particulate filter (DPF) at various steady conditions. Under high speed and load conditions, the particle filtering efficiency was decreased by the partial combustion of trapped particles inside the DPF because of the high exhaust temperature caused by the increased particle number concentration. Retarded fuel injection timing and higher EGR rates led to increased particle number emissions. As the temperature inside the DPF increased from 25 °C to 300 °C, the peak particle number level was reduced by 70% compared to cold start conditions. High levels of nucleation mode particle generation were found in the deceleration phases during the transient tests

Estimation of the spatial profile of neuromodulation and the temporal latency in motor responses induced by focused ultrasound brain stimulation

This study investigates the spatial profile and the temporal latency of the brain stimulation induced by the transcranial application of pulsed focused ultrasound (FUS). The site of neuromodulation was detected using 2-deoxy-2-[18F]fluoro-d-glucose PET immediately after FUS sonication on the unilateral thalamic area of Sprague–Dawley rats. The latency of the stimulation was estimated by measuring the time taken from the onset of the stimulation of the appropriate brain motor area to the corresponding tail motor response. The brain area showing elevated glucose uptake from the PET image was much smaller (56±10% in diameter, 24±6% in length) than the size of the acoustic focus, which is conventionally defined by the full-width at half-maximum of the acoustic intensity field. The spatial dimension of the FUS-mediated neuromodulatory area was more localized, approximated to be full-width at 90%-maximum of the acoustic intensity field. In addition, the time delay of motor responses elicited by the FUS sonication was 171±63 (SD) ms from the onset of sonication. When compared with latencies of other nonultrasonic neurostimulation techniques, the longer time delay associated with FUS-mediated motor responses is suggestive of the nonelectrical modes of neuromodulation, making it a distinctive brain stimulation method

Image-guided transcranial focused ultrasound stimulates human primary somatosensory cortex

Focused ultrasound (FUS) has recently been investigated as a new mode of non-invasive brain stimulation, which offers exquisite spatial resolution and depth control. We report on the elicitation of explicit somatosensory sensations as well as accompanying evoked electroencephalographic (EEG) potentials induced by FUS stimulation of the human somatosensory cortex. As guided by individual-specific neuroimage data, FUS was transcranially delivered to the hand somatosensory cortex among healthy volunteers. The sonication elicited transient tactile sensations on the hand area contralateral to the sonicated hemisphere, with anatomical specificity of up to a finger, while EEG recordings revealed the elicitation of sonication-specific evoked potentials. Retrospective numerical simulation of the acoustic propagation through the skull showed that a threshold of acoustic intensity may exist for successful cortical stimulation. The neurological and neuroradiological assessment before and after the sonication, along with strict safety considerations through the individual-specific estimation of effective acoustic intensity in situ and thermal effects, showed promising initial safety profile; however, equal/more rigorous precautionary procedures are advised for future studies. The transient and localized stimulation of the brain using image-guided transcranial FUS may serve as a novel tool for the non-invasive assessment and modification of region-specific brain functionopen43

Hierarchical Multiscale Hyperporous Block Copolymer Membranes via Tunable Dual-Phase Separation

The rational design and realization of revolutionary porous structures have been long-standing challenges in membrane science. We demonstrate a new class of amphiphilic polystyrene-block-poly(4-vinylpyridine) block copolymer (BCP)-based porous membranes featuring hierarchical multiscale hyperporous structures. The introduction of surface energy-modifying agents and the control of major phase separation parameters (such as nonsolvent polarity and solvent drying time) enable tunable dual-phase separation of BCPs, eventually leading to macro/nanoscale porous structures and chemical functionalities far beyond those accessible with conventional approaches. Application of this BCP membrane to a lithium-ion battery separator affords exceptional improvement in electrochemical performance. The dual-phase separation-driven macro/nanopore construction strategy, owing to its simplicity and tunability, is expected to be readily applicable to a rich variety of membrane fields including molecular separation, water purification, and energy-related devices.clos

Dissection Manual for Open Rhinoseptoplasty in a Silicone Nose Model

Open rhinoseptoplasty has been widely performed in the field of otorhinolaryngology. However, from the perspective of beginners, rhinoseptoplasty is a hard-to-learn surgery that involves a relatively steep learning curve. Therefore, practical guidance is essential to enhance the skills needed for excellent surgical outcomes. Here, we provide a step-wise dissection manual using a commercialized silicone nose model designed for rhinoseptoplasty. The contents include general approaches with regard to transcolumellar inverted V incision, flap elevation, osteotomy, septoplasty, modification of the lower lateral cartilage for tip surgery, and dorsal augmentation using silicone implants. In addition, we introduce novel techniques such as dorsal augmentation using a ready-made mold with tissue glue applied to diced cartilage and polycaprolactone mesh for rhinoseptoplasty. The present study also provides photos of individual surgical procedures using a silicone nose model for actual guidance. The authors expect that this manual will help beginning rhinoseptoplasty surgeons improve their confidence

Impact of national policy on hand hygiene promotion activities in hospitals in Korea

Background After the Middle East respiratory syndrome coronavirus outbreak in Korea in 2015, the Government established a strategy for infection prevention to encourage infection control activities in hospitals. The new policy was announced in December 2015 and implemented in September 2016. The aim of this study is to evaluate how infection control activities improved within Korean hospitals after the change in government policy. Methods Three cross-sectional surveys using the WHO Hand Hygiene Self-Assessment Framework (HHSAF) were conducted in 2013, 2015, and 2017. Using a multivariable linear regression model, we analyzed the change in total HHSAF score according to survey year. Results A total of 32 hospitals participated in the survey in 2013, 52 in 2015, and 101 in 2017. The number of inpatient beds per infection control professionals decreased from 324 in 2013 to 303 in 2015 and 179 in 2017. Most hospitals were at intermediate or advanced levels of progress (90.6% in 2013, 86.6% in 2015, and 94.1% in 2017). In the multivariable linear regression model, total HHSAF score was significantly associated with hospital teaching status (β coefficient of major teaching hospital, 52.6; 95% confidence interval [CI], 8.9 to 96.4; P = 0.018), beds size (β coefficient of 100 beds increase, 5.1; 95% CI, 0.3 to 9.8; P = 0.038), and survey time (β coefficient of 2017 survey, 45.1; 95% CI, 19.3 to 70.9; P = 0.001). Conclusions After the new national policy was implemented, the number of infection control professionals increased, and hand hygiene promotion activities were strengthened across Korean hospitals.This work supported by grants (2017 N-E2805–00) from Korea Centers for Disease Control, which had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript

Non-Invasive Brain-to-Brain Interface (BBI): Establishing Functional Links between Two Brains

Transcranial focused ultrasound (FUS) is capable of modulating the neural activity of specific brain regions, with a potential role as a non-invasive computer-to-brain interface (CBI). In conjunction with the use of brain-to-computer interface (BCI) techniques that translate brain function to generate computer commands, we investigated the feasibility of using the FUS-based CBI to non-invasively establish a functional link between the brains of different species (i.e. human and Sprague-Dawley rat), thus creating a brain-to-brain interface (BBI). The implementation was aimed to non-invasively translate the human volunteer's intention to stimulate a rat's brain motor area that is responsible for the tail movement. The volunteer initiated the intention by looking at a strobe light flicker on a computer display, and the degree of synchronization in the electroencephalographic steady-state-visual-evoked-potentials (SSVEP) with respect to the strobe frequency was analyzed using a computer. Increased signal amplitude in the SSVEP, indicating the volunteer's intention, triggered the delivery of a burst-mode FUS (350 kHz ultrasound frequency, tone burst duration of 0.5 ms, pulse repetition frequency of 1 kHz, given for 300 msec duration) to excite the motor area of an anesthetized rat transcranially. The successful excitation subsequently elicited the tail movement, which was detected by a motion sensor. The interface was achieved at 94.0 +/- 3.0% accuracy, with a time delay of 1.59 +/- 1.07 sec from the thought-initiation to the creation of the tail movement. Our results demonstrate the feasibility of a computer-mediated BBI that links central neural functions between two biological entities, which may confer unexplored opportunities in the study of neuroscience with potential implications for therapeutic applications.open12

Formation and characterization of conductive magnetite-embedded granules in upflow anaerobic sludge blanket reactor treating dairy wastewater

Promoting direct interspecies electron transfer (DIET) with conductive additives has proved effective in improving anaerobic digestion performance and stability. However, its application is limited by the need to replenish the washout loss of conductive materials. This study reports the formation of conductive magnetite-embedded granular sludge and its long-term influence on the performance of upflow anaerobic sludge blanket reactors treating dairy wastewater. The magnetite-supplemented reactor maintained better performance than the no-magnetite control, with greater sludge settling and electron transport activity, throughout the 192-d experiment at increasing organic loading rates (1.2???8.5 g chemical oxygen demand/L??d). The abundance of electroactive microbes also remained higher in the magnetite-supplemented reactor. The results suggest that DIET-based electric syntrophy was promoted in the magnetite-embedded granules. This study is the first to demonstrate the self-embedment of submicron conductive material into granular sludge and its benefits. These findings offer a new approach to enhancing anaerobic granular sludge systems

The potential use of human urine as a solvent for biogas upgrading

Biogas upgrading through chemical absorption is an energy-intensive and costly process, but it is essential for the higher-value utilization of biogas as biomethane. The loss of absorbents and the energy consumption for their regeneration lower the economic viability of the process. This study investigated the potential of human urine as an economical and sustainable source of solvent for biogas upgrading. Hydrolyzed urine (HU) is rich in ammonia (>4.4 g N/L) and alkaline (approximately pH 9), which makes it attractive as an absorbent to capture CO2. The hydrolysis characteristics of urine were assessed with and without urease addition at different temperatures (4, 25, and 35 ??C). Urease induced immediate urine hydrolysis, and temperature had a more significant effect on the hydrolysis rate when urease was not added. Conductivity, but not pH, proved to be a reliable indicator for monitoring urine hydrolysis. The CO2 capture capacity observed in the biogas upgrading experiments with simulated biogas (60% CH4 and 40% CO2, v/v) was 0.41???0.53 mol CO2/mol total ammonia nitrogen (TAN). The experiments using real biogas (71% CH4) showed that CO2 was effectively captured by HU with complete removal of H2S (2440 ppmv). This study is the first to demonstrate the direct use of HU as a sole solvent for biogas upgrading and suggest the possibility of recovering fertilizer material (e.g., ammonium bicarbonate, NH4HCO3) from the spent HU. The results suggest interesting opportunities to improve the economic feasibility of biogas upgrading and to valorize human urine