SciCombinator

Discover the most talked about and latest scientific content & concepts.

23

Patients with essential thrombocythemia (ET) are at high risk for both thrombosis and hemorrhage.

Concepts: Risk, Risk management

23

The ability to generate heat under an alternating magnetic field (AMF) makes magnetic iron oxide nanoparticles (MIONs) an ideal heat source for biomedical applications including cancer thermoablative therapy, tissue preservation and remote control of cell function. However, there is a lack of quantitative understanding of the mechanisms governing heat generation of MIONs, and the optimal nanoparticle size for magnetic fluid heating (MFH) applications. Here we show that MIONs with large sizes (> 20nm) have significantly higher specific absorption rate (SAR) than that predicted by the widely used linear theory of MFH. The heating efficiency of MIONs in both the superparamagnetic and ferromagnetic regimes increased with size, which can be accurately characterized with a modified dynamic hysteresis model. In particular, the 40 nm ferromagnetic nanoparticles have an SAR value approaching the theoretical limit under a clinically relevant AMF. An in vivo study further demonstrated that the 40 nm MIONs could effectively heat tumor tissues at a minimal dose. Our experimental results and theoretical analysis on nanoparticle heating offer important insight into the rationale design of MION-based MFH for therapeutic applications.

Concepts: Scientific method, Magnetic field, Iron oxide, Nanoparticle, Magnet, Magnetism, Ferromagnetism, Specific absorption rate

4

Objective To quantify the impact of cancer (all cancers combined and major sites) compared with cardiovascular disease (CVD) on longevity worldwide during 1981-2010.Design Retrospective demographic analysis using aggregated data.Setting National civil registration systems in member states of the World Health Organization.Participants 52 populations with moderate to high quality data on cause specific mortality.Main outcome measures Disease specific contributions to changes in life expectancy in ages 40-84 (LE40-84) over time in populations grouped by two levels of Human Development Index (HDI) values.Results Declining CVD mortality rates during 1981-2010 contributed to, on average, over half of the gains in LE40-84; the corresponding gains were 2.3 (men) and 1.7 (women) years, and 0.5 (men) and 0.8 (women) years in very high and medium and high HDI populations, respectively. Declines in cancer mortality rates contributed to, on average, 20% of the gains in LE40-84, or 0.8 (men) and 0.5 (women) years in very high HDI populations, and to over 10% or 0.2 years (both sexes) in medium and high HDI populations. Declining lung cancer mortality rates brought about the largest LE40-84 gain in men in very high HDI populations (up to 0.7 years in the Netherlands), whereas in medium and high HDI populations its contribution was smaller yet still positive. Among women, declines in breast cancer mortality rates were largely responsible for the improvement in longevity, particularly among very high HDI populations (up to 0.3 years in the United Kingdom). In contrast, losses in LE40-84 were observed in many medium and high HDI populations as a result of increasing breast cancer mortality rates.Conclusions The control of CVD has led to substantial gains in LE40-84 worldwide. The inequality in improvement in longevity attributed to declining cancer mortality rates reflects inequities in implementation of cancer control, particularly in less resourced populations and in women. Global actions are needed to revitalize efforts for cancer control, with a specific focus on less resourced countries.

Concepts: Cancer, Breast cancer, Metastasis, Lung cancer, Cancer staging, Demography, Life expectancy, Human Development Index

4

Objective To test the hypotheses that physical activity in midlife is not associated with a reduced risk of dementia and that the preclinical phase of dementia is characterised by a decline in physical activity.Design Prospective cohort study with a mean follow-up of 27 years.Setting Civil service departments in London (Whitehall II study).Participants 10 308 participants aged 35-55 years at study inception (1985-88). Exposures included time spent in mild, moderate to vigorous, and total physical activity assessed seven times between 1985 and 2013 and categorised as “recommended” if duration of moderate to vigorous physical activity was 2.5 hours/week or more.Main outcome measures A battery of cognitive tests was administered up to four times from 1997 to 2013, and incident dementia cases (n=329) were identified through linkage to hospital, mental health services, and mortality registers until 2015.Results Mixed effects models showed no association between physical activity and subsequent 15 year cognitive decline. Similarly, Cox regression showed no association between physical activity and risk of dementia over an average 27 year follow-up (hazard ratio in the “recommended” physical activity category 1.00, 95% confidence interval 0.80 to 1.24). For trajectories of hours/week of total, mild, and moderate to vigorous physical activity in people with dementia compared with those without dementia (all others), no differences were observed between 28 and 10 years before diagnosis of dementia. However, physical activity in people with dementia began to decline up to nine years before diagnosis (difference in moderate to vigorous physical activity -0.39 hours/week; P=0.05), and the difference became more pronounced (-1.03 hours/week; P=0.005) at diagnosis.Conclusion This study found no evidence of a neuroprotective effect of physical activity. Previous findings showing a lower risk of dementia in physically active people may be attributable to reverse causation-that is, due to a decline in physical activity levels in the preclinical phase of dementia.

Concepts: Cohort study, Cohort, Epidemiology, Proportional hazards models, Actuarial science, Relative risk, Physical exercise, Cognition

3

Objective To characterize rates and trends over time of emergency department treatment-and-discharge stays, repeat observation stays, inpatient stays, any hospital revisit, and death within 30 days of discharge from observation stays.Design Retrospective cohort study.Setting 4750 hospitals in the USA.Participants Nationally representative sample of Medicare fee for service beneficiaries aged 65 or over discharged after 363 037 index observation stays, 2 540 000 index emergency department treatment-and-discharge stays, and 2 667 525 index inpatient stays from 2006-11.Main outcome measures Rates of emergency department treatment-and-discharge stays, observation stays, inpatient stays, any hospital revisit, and death within 30 days of discharge from index observation stays. Rates were compared with corresponding outcomes within 30 days of discharge from both index emergency department treatment-and-discharge stays and index inpatient stays.Results Among 363 037 index observation stays resulting in discharge from 2006-11, 30 day rates of emergency department treatment-and-discharge stays were 8.4%, repeat observation stays were 2.9%, inpatient stays were 11.2%, any hospital revisit was 20.1%, and death was 1.8%. Of all revisits, 49.7% were for inpatient stays. Revisit rates for emergency department treatment-and-discharge stays, repeat observation stays, and any hospital revisit increased from 2006-11 (P<0.001 for trend), while 30 day rates of inpatient stays (P=0.054 for trend) and 30 day mortality (P=0.091 for trend) were both unchanged. Averaged over the study period, 30 day rates of any hospital revisit were similar after discharge from index emergency department treatment-and-discharge stays (19.9%) and index observation stays (20.1%), as was 30 day mortality (1.8% for both). Rates of any hospital revisit (21.8%) and death (5.2%) were highest after discharge from index inpatient stays.Conclusions Hospital revisits are common after discharge from observation stays, frequently result in inpatient hospitalizations, and have increased over time among Medicare beneficiaries. As revisit rates are similar after emergency department and observation stays, strategies shown to enhance emergency department transitional care may be reasonable starting points to improve post-observation outcomes.

Concepts: Cohort study, Health insurance, Hospital

0

Mechanochemical activation of metal oxides is studied by a novel methodology based on solid state reaction with a stable radical specie. Such approach corroborates that vacancy formation by high energy ball milling, also in nonreducible oxides, is responsible for electron release on particles' surfaces. This finding suggests a new defect engineering strategy to improve effectiveness of metal oxides as co-milling reagent for halogenated organic pollutant destruction. Results prove that high valent metal doping of a commonly employed co-milling reagent such as CaO determines 2.5 times faster pollutant degradation rate. This enhancement is due to electron-rich defects generated by the dopant; electrons are transferred to the organic pollutant thus causing its mineralization. The proposed strategy can be easily applied to other reagents.

Concepts: Electron, Oxygen, Quantum mechanics, Particle physics, Ion, Chemical reactions, Solid state

0

Stabilization of Cu, Zn, Cd, Hg, Cr and As in soil using tetramethylammonium (TMA) and dodecyltrimethylammonium (DTMA) modified bentonites (T-Bents and D-Bents) as amendments was investigated. Toxicity characteristic leaching procedure (TCLP) was used to quantify the metal mobility after soil treatment. The structural parameters of modified bentonites, including the BET surface area, basal spacing and zeta potential were obtained as a function of the TMA and DTMA loading at 40, 80, 120, 160 and 200% of the bentonite’s cation exchange capacity, respectively. The results indicated that the characteristics of the organo-bentonites fundamentally varied depending on the species and concentration of modifiers loaded on bentonite. T-Bents and D-Bents manifested distinct immobilization effectiveness towards various metals. In association with the organo-bentonite characteristics, the main interactive mechanisms for Cu, Zn and Cd proceeded via cation exchange, Hg proceeded via physical adsorption and partitioning, Cr and As proceeded via specific adsorption and electrostatic attraction, respectively. This study provided operational and mechanistic basis for optimizing the organic clay synthesis and selecting as the appropriate amendment for remediation of heavy metal contaminated soils.

Concepts: Colloid, Zinc, Heavy metal music, Heavy metal, Tungsten, BET theory, Cation exchange capacity, System of a Down

0

Apart from the contaminant removal, the remediation of agricultural soil should also pay more attention to soil nutrient retention and biogeochemical cycling. This study aimed to evaluate changes of soil properties, potential nitrification rates (PNRs), and functional gene abundances and link their relationships after remediating co-contaminated agricultural soil with Medicago sativa L. (alfalfa) planting, alone or together with biochar application. Compared with the control (CK), alfalfa planting, alone or together with biochar application, could significantly increase soil organic matter (SOM) contents and discrepantly affect soil pH values. The PNRs of the amended treatments were significantly higher than that of the CK. Moreover, alfalfa plantings also enhanced the abundances of functional genes related to soil nitrification and denitrification, with the sole exception of nosZ gene. Stepwise regression analysis revealed that the PNRs were best described by the gene abundance ratios of AOB amoA/nifH and nirS gene abundances. Compared with the CK, alfalfa planting, alone or with biochar application, could restore nitrogen cycling in the co-contaminated agricultural soil and enhance the PNRs via decreasing contaminant bio-availabilities and increasing SOM contents and gene abundance ratios of AOB amoA/nifH.

Concepts: Bacteria, Soil, Nitrogen, Nitrogen fixation, Stepwise regression, Denitrification, Nitrification, Nitrogen cycle

0

In a wide range of indoor air pollutants, formaldehyde is one of the most-used and best-known substances. In order to protect human health, many countries have established threshold values for the release of formaldehyde from miscellaneous products and revise them constantly. Compliance with these regulations is usually assessed by emission test chamber measurements or derived methods. To control and improve the mechanisms of an emission test chamber, a reliable reference source with sample mimicking emission properties is required but not available so far. This study describes a permeation-controlled reference source based on the application of paraformaldehyde as formaldehyde releasing polymeric compound. Interactions between the formaldehyde release of the source and the governing chamber parameters temperature, relative humidity and air velocity were investigated in 1 m(3) emission chambers. Depending on the conditions, constant formaldehyde concentrations between approximately 10 ppb and 150 ppb can be adjusted for up to 600 h. A linear correlation between the logarithm of the chamber concentration and the reciprocal temperature was found. The results support the feasibility of the source for validation of emission test chamber performance.

Concepts: Humidity, Relative humidity, Derivative, Psychrometrics, Global warming, Atmospheric thermodynamics

0

Polycyclic aromatic hydrocarbons (PAHs) have accumulated ubiquitously inArctic environments, where re-volatilization of certain organic pollutants as a result of climate change has been observed. To investigate the fate of semivolatile organic compounds in the Arctic, dissolved PAHs in the surface seawaters from the temperate Pacific Ocean to the Arctic Ocean, as well as a water column in the Arctic Ocean, were collected during the 4th Chinese National Arctic Research Expedition in summer 2010. The total concentrations of seven dissolved PAHs in surface water ranged from 1.0 to 5.1 ng L(-1), decreasing with increasing latitude. The vertical profile of PAHs in the Arctic Ocean was generally characteristic of surface enrichment and depth depletion, which emphasized the role of vertical water stratification and particle settling processes. A level III fugacity model was developed in the Bering Sea under steady state assumption. Model results quantitatively simulated the transfer processes and fate of PAHs in the air and water compartments, and highlighted a summer air-to-sea flux of PAHs in the Bering Sea, which meant that the ocean served as a sink for PAHs, at least in summer. Acenaphthylene and acenaphthene reached equilibrium in air-water diffusive exchange, and any perturbation, such as a rise in temperature, might lead to disequilibrium and remobilize these compounds from their Arctic reservoirs.

Concepts: Climate, Polycyclic aromatic hydrocarbon, Pacific Ocean, Canada, Ocean, Arctic Ocean, Arctic Circle, Bering Strait