20 research outputs found
Study of nano-mechanical performance of pretreated natural fiber in ldpe composite for packaging applications
No full textIn this work, the effects of chemical pretreatment and different fiber loadings on mechanical properties of the composites at the sub-micron scale were studied through nanoindentation. The composites were prepared by incorporating choline chloride (ChCl) pretreated rice husk waste (RHW) in low-density polyethylene (LDPE) using melt processing, followed by a thermal press technique. Nanoindentation experiments with quasi continuous stiffness mode (QCSM) were performed on the surface of produced composites with varying content of pretreated RHW (i.e., 10, 15, and 20 wt.%). Elastic modulus, hardness, and creep properties of fabricated composites were measured as a function of contact depth. The results confirmed the appreciable changes in hardness, elastic modulus, and creep rate of the composites. Compliance curves indicated that the composite having 20 wt.% of pretreated RHW loading was harder compared to that of the pure LDPE and other composite samples. The values of elastic modulus and hardness of the composite containing 20 wt.% pretreated RHW were increased by 4.1% and 24% as compared to that of the pure LDPE, respectively. The creep rate of 42.65 nm/s and change in depth of 650.42 nm were also noted for the composite with RHW loading of 20 wt.%, which showed the substantial effect of holding time at an applied peak load of 100 mN. We believe that the developed composite could be a promising biodegradable packaging material due to its good tribo-mechanical performance.Rivers, Ports, Waterways and Dredging Engineerin
Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles
No full textA measurement campaign (IMBALANCE) conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures,-30°C,-35°C and-40°C. Freshly emitted diesel particles showed ice formation only at-40°C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at-35°C. Wood burning particles also act as ice nuclei (IN) at-40°C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at-35°C whereas no ice nucleation was observed at-30°C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below-40°C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds. © 2013 Author(s)
A prospective pilot study of the effect of acupuncture on insulin sensitivity in women with polycystic ovary syndrome and insulin resistance
No full textObjective: To test the hypothesis that acupuncture improves insulin sensitivity in women with polycystic ovary syndrome (PCOS) and insulin resistance (IR). Design: Prospective pilot study. Setting: Guangzhou, China, 2014–2016. Participants: Eighty women with PCOS aged 18–40 years with body mass index (BMI) above 18.5 kg/m2 and with homeostatic model assessment for insulin resistance (HOMA-IR) index ⩾2.14. Interventions: Subjects received acupuncture with combined manual and low-frequency electrical stimulation of the needles three times per week for 6 months. Primary and secondary outcome measures: The primary outcome was the change in HOMA-IR after 6 months of acupuncture relative to baseline. Secondary outcomes included changes after 6 months of acupuncture and at 3 months of follow-up (both relative to baseline) in oral glucose tolerance test (OGTT) parameters (glucose and insulin levels), anthropometric measurements, and circulating metabolic and endocrine variables. Results: HOMA-IR and fasting plasma glucose and insulin levels were significantly decreased after 6 months of acupuncture, and both HOMA-IR and fasting insulin remained significantly decreased at 3 months of follow-up. In a subgroup analysis of normal-weight and overweight/obese women, HOMA-IR was reduced after 6 months of acupuncture in both subgroups, but there was no significant difference between the two groups. Conclusions: Acupuncture treatment in Chinese women with PCOS and IR was associated with an encouraging improvement in insulin sensitivity. Further randomized controlled studies are required to confirm the efficacy of acupuncture for this indication. © The Author(s) 2020.postprin
Changes in fire regimes since the last glacial maximum: an assessment based on a global synthesis and analysis of charcoal data
No full textFire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ?11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ?19,000 to ?17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ?13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ?3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load
Searching for dark matter signals from local dwarf spheroidal galaxies at low radio frequencies in the GLEAM survey
No full text© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society The search for emission from weakly interacting massive particle (WIMP) dark matter annihilation and decay has become a multipronged area of research not only targeting a diverse selection of astrophysical objects, but also taking advantage of the entire electromagnetic spectrum. The decay of WIMP particles into standard model particles has been suggested as a possible channel for synchrotron emission to be detected at low radio frequencies. Here, we present the stacking analysis of a sample of 33 dwarf spheroidal (dSph) galaxies with low-frequency (72-231 MHz) radio images from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. We produce radial surface brightness profiles of images centred upon each dSph galaxy with background radio sources masked. We remove 10 fields from the stacking due to contamination from either poorly subtracted, bright radio sources or strong background gradients across the field. The remaining 23 dSph galaxies are stacked in an attempt to obtain a statistical detection of any WIMP-induced synchrotron emission in these systems. We find that the stacked radial brightness profile does not exhibit a statistically significant detection above the 95 per cent confidence level of ∼1.5 mJy beam−1. This novel technique shows the potential of using low-frequency radio images to constrain fundamental properties of particle dark matter
Anomalous origin of right coronary artery from the left coronary sinus: Incidence, characteristics, and a systematic approach for rapid diagnosis
No full textTwenty-three patients were found to have anomalous origin of right coronary artery from the left coronary sinus (LCS) from January 2000 to October 2003. The mean age was 58.6 ± 14.3 years with male predominance (56.5%). Cardiovascular risk factors were found in 18 (78.3%) patients while coronary artery disease was seen in 13 (56.5%) patients. Among the coronary artery disease patients, the left anterior descending artery was the most commonly involved, followed by the right coronary artery and the left circumflex artery. Right coronary artery dominance was seen in 19 (82.6%) patients. The anomalous right coronary artery originates within the left coronary sinus in 17 (73.9%) patients while from the left aortic wall above the sinus in 6 (26.1%) patients only. Congenital heart disease and acquired valvular heart disease were the most common associated conditions. The author will share his experience and suggest a four-step approach of early recognition and selection of the anomalous right coronary artery ostium. Using the suggested strategy, most of the anomalous right coronary artery could be opacified with a left amplatz 1 catheter. Aortogram was needed only in 47.8% of cases.link_to_subscribed_fulltex
Sizing method for stormwater har vesting tanks using daily resolution rainfall and water demand data sets
No full textEste trabajo presenta un método simplificado para el dimensionamiento de tanques de aprovechamiento de aguas lluvias (AAL). Este método considera cuencas tributarias heterogéneas y caudales de demanda de agua. Se propone tener en cuenta la probabilidad para suministrar la demanda de agua, así como el paso de tiempo necesario de recolección más probable y sus respectivas variabilidades. El método se aplicó a un estudio específico de caso (Pontificia Universidad Javeriana, proyecto AAL), con 73 años de información de precipitación a resolución diaria (entre 1936-2010). Para el análisis se utilizaron diferentes períodos de tiempo, los volúmenes del tanque con el tiempo de recolección fueron los siguientes: (i) para el conjunto entero de datos 76 años: 395 m3 (28 días, probabilidad: 78%); (ii) para los últimos diez años: 494 m3 (35 días, probabilidad: 89%); (iii) para los últimos cinco años: 346 m3 (25 días, probabilidad: 84%); (iv) para el último año: 155 a 198 m3 (11 a 14 días, probabilidad: 89-90%). Estos resultados parecen estar influenciados por una evolución de la altura de lluvia en los diferentes períodos seleccionados, lo cual será estudiado en investigaciones posteriores.This work presents a simplified method for rainwater harvesting (RWH) tank sizing using long day-resolution rainfall time series. This method considers heterogeneous contributing catchments and water demand flow rates. For the tank sizing, we proposed to take into account the probability to supply the water demand, as well as the most needed probable time step and their respective variabilities. The method was applied to a specific case study (Pontificia Universidad Javeriana, RHW project), with 73 years of daily-resolution rainfall information (between 1936-2010). For the analysis we used different time periods from data-set and the results were: (i) for the whole data-set 76 years: 395 m3 (28 days, probability: 78%); (ii) for the last ten years: 494 m3 (35 days, probability: 89%); (iii) for the last five years: 346 m3 (25 days, probability: 84%); (iv) for the last year: 155-198 m3 (11-14 days, probability: 89-90%). These results seem to be influenced by an evolution of rainfall depth in different selected periods, which will be studied in further researches
Sizing method for stormwater har vesting tanks using daily resolution rainfall and water demand data sets
No full textEste trabajo presenta un método simplificado para el dimensionamiento de tanques de aprovechamiento de aguas lluvias (AAL). Este método considera cuencas tributarias heterogéneas y caudales de demanda de agua. Se propone tener en cuenta la probabilidad para suministrar la demanda de agua, así como el paso de tiempo necesario de recolección más probable y sus respectivas variabilidades. El método se aplicó a un estudio específico de caso (Pontificia Universidad Javeriana, proyecto AAL), con 73 años de información de precipitación a resolución diaria (entre 1936-2010). Para el análisis se utilizaron diferentes períodos de tiempo, los volúmenes del tanque con el tiempo de recolección fueron los siguientes: (i) para el conjunto entero de datos 76 años: 395 m3 (28 días, probabilidad: 78%); (ii) para los últimos diez años: 494 m3 (35 días, probabilidad: 89%); (iii) para los últimos cinco años: 346 m3 (25 días, probabilidad: 84%); (iv) para el último año: 155 a 198 m3 (11 a 14 días, probabilidad: 89-90%). Estos resultados parecen estar influenciados por una evolución de la altura de lluvia en los diferentes períodos seleccionados, lo cual será estudiado en investigaciones posteriores.This work presents a simplified method for rainwater harvesting (RWH) tank sizing using long day-resolution rainfall time series. This method considers heterogeneous contributing catchments and water demand flow rates. For the tank sizing, we proposed to take into account the probability to supply the water demand, as well as the most needed probable time step and their respective variabilities. The method was applied to a specific case study (Pontificia Universidad Javeriana, RHW project), with 73 years of daily-resolution rainfall information (between 1936-2010). For the analysis we used different time periods from data-set and the results were: (i) for the whole data-set 76 years: 395 m3 (28 days, probability: 78%); (ii) for the last ten years: 494 m3 (35 days, probability: 89%); (iii) for the last five years: 346 m3 (25 days, probability: 84%); (iv) for the last year: 155-198 m3 (11-14 days, probability: 89-90%). These results seem to be influenced by an evolution of rainfall depth in different selected periods, which will be studied in further researches
Measuring luteinising hormone pulsatility with a robotic aptamer-enabled electrochemical reader
No full textThis is the final version. Available from the publisher via the DOI in this record.Normal reproductive functioning is critically dependent on pulsatile secretion of luteinising hormone (LH). Assessment of LH pulsatility is important for the clinical diagnosis of reproductive disorders, but current methods are hampered by frequent blood sampling coupled to expensive serial immunochemical analysis. Here, we report the development and application of a Robotic APTamer-enabled Electrochemical Reader (RAPTER) electrochemical analysis system to determine LH pulsatility. Through selective evolution of ligands by exponential enrichment (SELEX), we identify DNA aptamers that bind specifically to LH and not to related hormones. The aptamers are integrated into electrochemical aptamer-based (E-AB) sensors on a robotic platform. E-AB enables rapid, sensitive and repeatable determination of LH concentration profiles. Bayesian Spectrum Analysis is applied to determine LH pulsatility in three distinct patient cohorts. This technology has the potential to transform the clinical care of patients with reproductive disorders and could be developed to allow real-time in vivo hormone monitoring.Hong Kong Health and Medical Research Fund (HMRF)National Institute for Health Research (NIHR)University of Hong Kong Outstanding Young Researcher Award 2015-16HKU Seed Fund for Translational and Applied ResearchEngineering and Physical Sciences Research Council (EPSRC)Medical Research Council (MRC
Deep Extragalactic VIsible Legacy Survey (DEVILS): evolution of the σSFR–M⋆ relation and implications for self-regulated star formation
No full textWe present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the PROSPECT spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 < z < 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time
