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It is shown that surfacing with feeding Nano oxides or Nano carbides into the weld pool leads to significant increase the wear resistance of deposited metal. Meanwhile, the information available in the literature on the optimal concentrations of Nano components corresponds only to specific surfacing conditions. Other surfacing conditions require additional experimental studies to determine optimal concentrations under these new conditions. Theoretical studies revealed that a change in the heat input of surfacing is accompanied by a change in the volume and mass of the weld pool, which leads to the changes in the mass concentrations of Nano components. It is shown that, the volume and mass of the weld pool may change almost by 3 times, and the mass percentage of Nano components by 2 times A method has been proposed for determining the mass fraction of Nano components in the weld pool at different heat inputs of surfacing. The experimental studies confirmed analytical predictions. The use of the proposed technique will make it possible to spread the technology of surfacing with feeding of Nano components into the weld pool without additional experimental studies. [ABSTRACT FROM AUTHOR]

The Gravity Recovery and Climate Experiment (GRACE) and GRACE‐Follow On missions have provided a global history of terrestrial water storage changes since 2002. Traditional GRACE products resolve monthly time‐variable gravity at spatial resolutions of 300–500 km, with many recent efforts focusing on regularized mass concentration (mascon) solutions to better resolve signals spatially. However, monthly resolution inhibits the applicability of GRACE to investigations of sub‐monthly signals. This study presents a new daily mass change solution estimated as deviations from the NASA Goddard Space Flight Center (GSFC) converged monthly mascon product and quantifies the fundamental trade‐off between temporal and spatial resolution in GRACE‐only solutions. As an iteration of the GSFC product, this daily solution represents a mixing of monthly information at higher relative spatial resolution with daily information at lower relative spatial resolution, resolving each temporal scale at the best resolution achievable without requiring hydrological model dependencies in the estimation. The resolution of the daily mascons is 300–400 km at high latitudes and 600–1,000 km lower, depending on each daily orbital track and the proximity of each mascon to constraint region boundaries (e.g., coastlines). Through simulations and model comparisons, we demonstrate that daily signals over areas larger than 400,000 km 2 are recoverable, with basins larger than 800,000 km 2 exhibiting strong signal recovery relative to leakage. This analysis establishes baselines for daily signal recovery from GRACE in the context of longer time scale solutions, characterizes leakage inherent in daily GRACE information, and creates new opportunities for applying GRACE to investigations of sub‐monthly signals. Key Points: Daily solutions are independently estimated as an iteration of the converged GSFC monthly masconsLarge spatial signals are recovered at daily and longer time scalesNoise and leakage are quantified, and significant hydrologic signals are recovered in large basins [ABSTRACT FROM AUTHOR]

Atmospheric PCDD/Fs and dl-PCBs samples were collected in Hochiminh city, Vietnam to address the effect of meteorological parameters, especially rainfall, on the occurrence and gas/particle partitioning of these persistent organic pollutants. The results indicate that PCDD/Fs and dl-PCBs concentrations in industrial site are higher than those measured in commercial and rural sites during both rainy and dry seasons. In terms of mass concentration, ambient PCDD/F levels measured in dry season are significantly higher than those measured in rainy season while dl-PCB levels do not vary significantly between rainy and dry seasons. The difference could be attributed to different gas/particle partitioning characteristics between PCDD/Fs and dl-PCBs. PCDD/Fs are found to be mainly distributed in particle phase while dl- PCBs are predominantly distributed in gas phase in both rainy and dry seasons. Additionally, Junge-Pankow and Harner-Bidleman models are applied to better understand the gas/particle partitioning of these pollutants in atmosphere. As a results, both PCDD/Fs and dl-PCBs are under non-equilibrium gas/particle partitioning condition, and PCDD/Fs tend to reach equilibrium easier in rainy season while there are no clear trend for dl-PCBs. Harner-Bidleman model performs better in evaluating the gas/particle partitioning of PCDD/Fs while Junge-Pankow model results in better prediction for dl-PCBs. [ABSTRACT FROM AUTHOR]

Beta-attenuation monitors are used worldwide to monitor PM mass concentration with high temporal resolution. Hourly PM10 and PM2.5 dry mass concentrations are publicly available with the tacit assumption that water is effectively removed prior to the measurement. However, as both the filter material of the monitor and the aerosol particles are capable of retaining a significant amount of water even at low relative humidities, the basic assumption may not be valid, resulting in significant bias in reported PM10 and PM2.5 concentrations. Here we show that in PM10 measurement, particle-free air can produce apparent hourly average PM concentrations in the range of 13+21 μg m-3 under conditions of fluctuating relative humidity. Positive and negative apparent readings are observed with increasing and decreasing relative humidities, respectively. Similar phenomena have been observed when the instrument filter was previously loaded with atmospheric aerosol. As a result the potential measurement biases in hourly readings arising from the interaction with water may be in the range of 53...+69%. [ABSTRACT FROM AUTHOR]

Sixteen U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and eleven non-priority isomers including some dibenzopyrenes were analyzed to evaluate health risk attributable to inhalation exposure to ambient PAHs and contributions of the non-priority PAHs in a megacity Nanjing, east China. The annual average mass concentration of the total 16 EPA priority PAHs in air was 51.1 ± 29.8 ng/m3, comprising up to 93% of the mass concentration of all 27 PAHs, however, the estimated Incremental Lifetime Cancer Risk (ILCR) due to inhalation exposure would be underestimated by 63% on average if only accounting the 16 EPA priority PAHs. The risk would be underestimated by 13% if only particulate PAHs were considered, though gaseous PAHs made up to about 70% of the total mass concentration. During the last fifteen years, ambient Benzo[a]pyrene decreased significantly in the city which was consistent with the declining trend of PAHs emissions. Source contributions to the estimated ILCR were much different from the contributions for the total mass concentration, calling for the introduce of important source-oriented risk assessments. Emissions from gasoline vehicles contributed to 12% of the total mass concentration of 27 PAHs analyzed, but regarding relative contributions to the overall health risk, gasoline vehicle emissions contributed 45% of the calculated ILCR. Dibenzopyrenes were a group of non-priority isomers largely contributing to the calculated ILCR, and vehicle emissions were probably important sources of these high molecular weight isomers. Ambient dibenzo[a,l]pyrene positively correlated with the priority PAH Benzo[g,h,i]perylene. The study indicates that inclusion of non-priority PAHs could be valuable for both PAH source apportionment and health risk assessment. [ABSTRACT FROM AUTHOR]

We applied a global three-dimensional chemical transport model (GEOS-Chem) to examine the impacts of the East Asian monsoon on the interannual variations of mass concentrations and direct radiative forcing (DRF) of black carbon (BC) over eastern China (110-125° E, 20-45° N). With emissions fixed at the year 2010 levels, model simulations were driven by the Goddard Earth Observing System (GEOS-4) meteorological fields for 1986-2006 and the Modern Era Retrospective-analysis for Research and Applications (MERRA) meteorological fields for 1980-2010. During the period of 1986-2006, simulated June-July-August (JJA) and December-January-February (DJF) surface BC concentrations were higher in MERRA than in GEOS-4 by 0.30 μg m-3 (44 %) and 0.77 μg m-3 (54 %), respectively, because of the generally weaker precipitation in MERRA. We found that the strength of the East Asian summer monsoon (EASM; East Asian winter monsoon, EAWM) negatively correlated with simulated JJA (DJF) surface BC concentrations (r = -0.7 (-0.7) in GEOS-4 and -0.4 (-0.7) in MERRA), mainly by the changes in atmospheric circulation. Relative to the 5 strongest EASM years, simulated JJA surface BC concentrations in the 5 weakest monsoon years were higher over northern China (110-125° E, 28-45° N) by 0.04-0.09 μg m-3 (3-11 %), but lower over southern China (110-125° E, 20-27° N) by 0.03-0.04 μg m-3 (10-11 %). Compared to the 5 strongest EAWM years, simulated DJF surface BC concentrations in the 5 weakest monsoon years were higher by 0.13-0.15 μg m-3 (5-8 %) in northern China and by 0.04-0.10 μg m-3 (3-12 %) in southern China. The resulting JJA (DJF) mean all-sky DRF of BC at the top of the atmosphere was 0.04 W m-2 (3 %; 0.03 W m-2, 2 %) higher in northern China but 0.06 W m-2 (14 %; 0.03 W m-2, 3 %) lower in southern China. In the weakest monsoon years, the weaker vertical convection at the elevated altitudes led to the lower BC concentrations above 1-2 km in southern China, and therefore the lower BC DRF in the region. The differences in vertical profiles of BC between the weakest and strongest EASM years (1998-1997) and EAWM years (1990-1996) reached up to -0.09 μg m-3 (-46 %) and -0.08 μg m-3 (-11 %) at 1-2 km in eastern China. [ABSTRACT FROM AUTHOR]

With the widespread use of titanium dioxide (TiO) human exposure is inevitable, but the exposure data on TiO are still limited. This study adopted off-line filter-based sampling combined with real-time activity-based monitoring to measure the concentrations in a workplace manufacturing TiO (primary diameter: 194 ± 108 nm). Mass concentrations (MCs) of aerosol particles in the packaging workshop (total dust: 3.17 mg/m, nano dust: 1.22 mg/m) were much higher than those in the milling workshop (total dust: 0.79 mg/m, nano dust: 0.31 mg/m) and executive office (total dust: 0.44 mg/m, nano dust: 0.19 mg/m). However, the MCs of TiO were at a relatively low level in the packaging workshop (total TiO: 46.4 μg/m, nano TiO: 16.7 μg/m) and milling workshop (total TiO: 39.4 μg/m, nano TiO: 19.4 μg/m) by ICP-MS. The number concentration (NC), surface area concentration (SAC) of aerosol particles potentially deposited in alveolar (SAC), and tracheobronchial (SAC) regions of lungs in the packaging workshop were (1.04 ± 0.89) × 10 particles/cm, 414.49 ± 395.07, and 86.01 ± 83.18 μm/cm, respectively, which were all significantly higher than those of the milling workshop [(0.12 ± 0.40) × 10 particles/cm, 75.38 ± 45.23, and 17.60 ± 9.22 μm/cm, respectively] as well as executive office and outdoor background ( p < 0.05). Activity-related characteristics were found in both workshops, and the time-variant characteristics showed very similar trends for 3 days in the packaging workshop. Our study provides important data of TiO particles exposure in the workplace. [ABSTRACT FROM AUTHOR]

We study archival HST [S II] 6716+30 and Hα images of the HH 34 outflow, taken in 1998.71 and in 2007.83. The ~9 yr time baseline and the high angular resolution of these observations allow us to carry out a detailed proper-motion study. We determine the proper motions of the substructure of the HH 34S bow shock (from the [S II] and Hα frames) and of the aligned knots within ~30" from the outflow source (only from the [S II] frames). We find that the present-day motions of the knots along the HH 34 jet are approximately ballistic, and that these motions directly imply the formation of a major mass concentration in ~900 yr, at a position similar to the one of the present-day HH 34S bow shock. In other words, we find that the knots along the HH 34 jet will merge to form a more massive structure, possibly resembling HH 34S. [ABSTRACT FROM AUTHOR]

Macroscopic concepts pertaining to the Unruh effect are elaborated and used to clarify its physical manifestations. Based on a description of the motion of accelerated, spatially extended laboratories in Minkowski space in terms of Poincaré transformations, it is shown that, from a macroscopic perspective, an accelerated observer will not register with his measuring instruments any global thermal effects of acceleration in the inertial (Minkowskian) vacuum state. As is explained, this result is not in conflict with the well-known fact that microscopic probes used as thermometers respond non-trivially to acceleration if coupled to the vacuum. But this response cannot be interpreted as the effect of some exchange of thermal energy with a gas surrounding the observer; in fact, it is induced by the measuring process itself. It is also shown that genuine equilibrium states in a uniformly accelerated laboratory cannot be spatially homogeneous. In particular, these states coincide with the homogeneous inertial vacuum at sufficiently large distances from the horizon of the observer and consequently have the same (zero) temperature there. The analysis is carried out in the theory of a free massless scalar field; however the conclusion that the Unruh effect is not of a macroscopic thermal origin is generally valid. [ABSTRACT FROM AUTHOR]