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Background: Our aim was to determine whether the Apparent Diffusion Coefficient is able to predict the presence of a symptomatic pineal cyst by detecting cerebral edema. Methods: We retrospectively analyzed MRIs of 45 patients with pineal cysts before and after resection and 51 patients without pineal cysts, comparing ADC values of thalamus, central, periventricular and subcortical white matter. Furthermore we evaluated cyst size and morphology and analyzed its correlation to ADC values in corresponding patients. Results: Differences between patients with symptomatic pineal cyst and control group were not significant (p = 0.200 – 0.968). ADC ratios did not change significantly after resection of the cyst (p = 0.575 – 0.862). Cyst size showed no significant correlation to ADC ratios (p = 0.071 – 0.918). Raw data analyses revealed more significance, especially periventricularly and in central white matter, which resulted in significant interhemispheric differences in ADC ratios in both subgroups (p < 0.001 and p = 0.031). MRI of 1.5T showed consistently higher values than 3T but mostly insignificant. Conclusion: Our analysis revealed no evidence that pineal cysts lead to intracerebral edema caused by venous compression. Since variability was higher than the differences seen, ADC sequences do not appear to be an appropriate diagnostic tool for symptomatic pineal cysts. [ABSTRACT FROM AUTHOR]

The complex thermal history imposed by the laser-based powder bed fusion of metals (PBF-LB/M) process is known to promote the evolution of unique microstructures. In the present study, metastable CrMnNi steels with different nickel contents and, thus, different phase stabilities are manufactured by PBF-LB/M. Results clearly reveal that an adequate choice of materials will allow to tailor mechanical properties as well as residual stress states in the as-built material to eventually redundantize any thermal post-treatment. The chemical differences lead to different phase constitutions in as-built conditions and, thus, affect microstructure evolution and elementary deformation mechanisms upon deformation, i.e., twinning and martensitic transformation. Such alloys designed for additive manufacturing (AM) highlight the possibility to tackle well-known challenges in AM such as limited damage tolerance, porosity and detrimental residual stress states without conducting any post treatments, e.g., stress relieve and hot isostatic pressing. From the perspective of robust design of AM components, indeed it seems to be a very effective approach to adapt the material to the process characteristics of AM. [ABSTRACT FROM AUTHOR]

Purpose: Incisional hernias often follow open abdominal surgery. A small-stitch-small-bite suture might close the incision durably. We analyzed specific details of this closure technique and assessed their influence on the closure stability.Methods: The effects of cyclic loads, simulating coughs were investigated on a bench test. We prepared porcine bellies in the median line and bovine flanks parallel to the muscle fibers with 15 cm long incisions. Then we punched round or rhomboid defects with a diameter of 5-10 cm into the center of the incision. Monomax® 2-0 and Maxon® 1 and 2-0 were used as suture materials. We tested the durability of the closure with pressure impacts of 210 mmHg repeated 425 times. Throughout the experiments, we modified the suturing technique, the surgeon, the tissue tension, the defect size and shape and the suture diameter.Results: Standardizing the suture technique improved the durability of the closure significantly. Any other variations showed minor influences after standardization. All incisions with round defects up to 7.5 cm width withstood 425 impacts using standardized suturing. Unstandardized sutures failed in all cases. When closing an incision with a 10 cm wide defect, the tissues ruptured frequently next to the suture line. We defined criteria to standardize this suturing technique. For the first time, we developed a suture factor related to the durability of a sutured tissue closure. We integrated the suture factor into the concept of biomechanically durable repairs.Conclusions: Suturing the abdominal wall with a standardized suturing technique improves its durability significantly. [ABSTRACT FROM AUTHOR]

The present study aims at identifying and analyzing challenges and prospects related to the use of pseudoelastic shape memory alloys for well-established double shear connections in timber engineering. The unique behavior of shape memory alloys will allow to bear large reversible deformations without loss of cohesion. Thereby, the main objective of the present work is to study the behavior of a connection that is able to stay completely reversible even upon very large deformations. In this context, the stiffness of the connection as well as functional and structural integrity and damping behavior have been improved by stepwise adaption of the detailing. Proof of concept is provided, and current limitations are discussed, based on the application of bolts made from a commercially available shape memory alloy. [ABSTRACT FROM AUTHOR]

Additive manufacturing has gained increasing attention in recent years in numerous industrial sectors due to its inherent characteristics, e.g. tool-free production and unprecedented freedom of design. However, in some applications such as heat exchangers the design has to follow certain restrictions, e.g. to allow for the removal of unfused powder, which can be enclosed in cavities. Moreover, in case multi-material parts are considered, the use of different powders during processing is often uneconomical since powder recycling is highly challenging. Therefore, the production of complex structures being characterized by limited accessibility and components made of different materials often require a subsequent joining process. Based on an analysis of state-of-the-art joining technologies employed for additively manufactured metal components, research gaps related to adhesive bonding are deduced. In light of the prevailing gaps, the influence of selective laser melting process parameters like laser power and build direction on the surface topography and, thus, on the bondability of the substrates are investigated. The mechanical tests reveal a high bond strength for the vertically oriented samples and the samples manufactured with a laser power of 400 W. Furthermore, a laser post-treatment of the SLM samples lead to an improvement of lap shear strength. Finally, results reporting on the ageing behaviour of these joints and an outlook on further research activities are given. [ABSTRACT FROM AUTHOR]

The blue color perception of Cherenkov radiation is often intuitively attributed to its spectrum. However observations usually take place through several meters of water which strongly modifies the original spectrum. A quantitative description of color allows to judge the relative importance of source spectrum versus water influence. This physics example nicely illustrates the scientific method of questioning accepted intuitive reasoning and explanations for phenomena. [ABSTRACT FROM AUTHOR]

A Co-Ni-Ga high-temperature shape memory alloy has been additively manufactured by directed energy deposition. Due to the highly anisotropic microstructure, i.e. columnar grains featuring a strong near-⟨001⟩ texture in build direction, the as-built material is characterized by a very low degree of constraints and, thus, shows excellent superelasticity without conducting a post-process heat treatment. As characterized by in situ deformation testing and post-mortem microstructural analysis, additive manufacturing employing directed energy deposition seems to be highly promising for processing of shape memory alloys, which often suffer difficult workability. The present work establishes a new pathway towards realization of high performance shape memory alloys by additive manufacturing and, thus, will stimulate further research in this field directed towards application. [ABSTRACT FROM AUTHOR]

Hydrochlorofluorocarbons (HCFCs), the main substitutes of chlorofluorocarbons, are regulated by the Montreal Protocol. Chinese HCFC emissions increased fast from the beginning of this century. However, limit reports based on atmospheric measurement are available for years after 2011, an important period when significant changes are expected. Combining atmospheric observations at seven sites across China with a FLEXible PARTicle dispersion model‐based Bayesian inversion technique, we estimate emission magnitudes and changes of four major HCFCs in China during 2011–2017. The emissions of all four HCFCs reached peaks before 2015. Our results agreed well with the reported bottom‐up inventories. The Chinese ozone depletion potential (ODP)‐weighted emission of the three most abundant HCFCs accounted for 37% of global totals from 2011 to 2016. The total emission of HCFC‐22 from China, the European Union, and the United States accounted approximately a half of the global totals, suggesting large HCFC emission emitted from the rest of the world. Plain Language Summary: Hydrochlorofluorocarbons (HCFCs) are used to replace chlorofluorocarbons, or well known as Freon, a group of gases which contribute to the polar ozone hole. However, HCFCs are also important ozone depletion substances and are regulated by the Montreal Protocol. As the largest developing country, the HCFC emissions in China are of great interest. In this study, we estimate emission magnitudes and changes of four major HCFCs in China over the period 2011–2017 based on atmospheric observations at seven sites. We find the emissions of all four HCFCs reached their peaks before 2015, which generally agree with the emission inventories estimated using production and consumption information, suggesting the effectiveness of the implementation of Montreal Protocol in China. However, there is a big gap between the total HCFC‐22 emission from China, the European Union, and the United States and global totals, suggesting large emissions from the rest of the world. Key Points: The Chinese emissions of HCFC‐22, HCFC‐141b, HCFC‐142b, and HCFC‐124 all reached peaks before 2015The Chinese ODP‐weighted emission of the three most abundant HCFCs accounted for 37% of global totals from 2011 to 2016Large gaps were found between the global HCFC‐22 emissions and total HCFC‐22 emissions from the European Union, the United States, and China [ABSTRACT FROM AUTHOR]

Copyright of Der Freie Zahnarzt is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Ventral hernia repair can be performed safely using meshes which are primarily stable upon dynamic intermittent straining (DIS) at recommended overlap. In specific clinical situations, e.g., at bony edges, bridging of the hernial orifice with reduced overlap might be necessary. To gain insight into the durability of various applications, two different meshes with the best tissue grip known so far were assessed.Methods: The model uses dynamic intermittent strain and comprises the repetition of submaximal impacts delivered via a hydraulically driven plastic containment. Pig tissue simulates a ventral hernia with a standardized 5 cm defect. Commercially available meshes classified as primarily stable at recommended overlap were used to bridge this defect at recommended and reduced overlap.Results: Using Parietex Progrip®, the peritoneum adds sufficient stability at least to a 2.5 cm overlap. Using Dynamesh Cicat®, four gluing spots with Glubran® are sufficient to stabilize a 3.75 cm overlap. A 2.5 cm overlap is stabilized with eight bonding spots Glubran® and 8 bonding spots combined with four sutures stabilize a 1.25 cm overlap. Here again, an intact peritoneum stabilizes the reconstruction significantly.Conclusions: Based on a pig tissue model, a total of 23 different conditions were tested. A DIS class A mesh can be easily stabilized bridging a 5 cm hernial orifice with reduced overlap. Caution must be exerted to extend these results to other DIS classes and larger hernial orifices. Further DIS investigations can improve the durability of hernia repair. [ABSTRACT FROM AUTHOR]

High frequency, in situ observations from 11 globally distributed sites for the period 1994-2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2. These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a topdown approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84±0.05 ppt yr-1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38±0.04 ppt yr-1 in 2010 with a further decline to an annual average rate of growth in 2013-2014 of -0.06±0.05 ppt yr-1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3±5.6 Gg yr-1 in 1994 to a maximum of 54.4±17.1 Gg yr-1 in 2011, declining to 52.5±20.1 Gg yr-1 in 2014 or 7.2±2.8 Tg-CO2 eq yr-1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called "bottom up" emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate (>20 Gg) of "bottom-up" reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions. [ABSTRACT FROM AUTHOR]

High frequency, in situ observations from 11 globally distributed sites for the period 1994-2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1- difluoroethane (HFC-152a, CH3CHF2/. These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a topdown approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84±0.05 ppt yr-1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38±0.04 ppt yr-1 in 2010 with a further decline to an annual average rate of growth in 2013-2014 of -0.06±0.05 ppt yr-1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3±5.6 Gg yr-1 in 1994 to a maximum of 54.4±17.1 Gg yr-1 in 2011, declining to 52.5±20.1 Gg yr-1 in 2014 or 7.2±2.8 Tg-CO2 eq yr-1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called "bottom up" emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate (>20 Gg) of "bottom-up" reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions. [ABSTRACT FROM AUTHOR]

High frequency, ground-based, in situ measurements from eleven globally-distributed sites covering 1994-2014, combined with measurements of archived air samples dating from 1978 onward and atmospheric transport models, have been used to estimate the growth of 1,1-difluoroethane (HFC-152a, CH3CHF2) mole fractions in the atmosphere and the global emissions required to derive the observed growth. HFC-152a is a significant greenhouse gas but since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). HFC-152a has exhibited substantial atmospheric growth since the first measurements reaching a maximum annualised global growth rate of 0.81 ± 0.05 ppt yr-1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annualised rate of growth has slowed to 0.38 ± 0.04 ppt yr-1 in 2010 with a further decline to an average rate of change in 2013-2014 of -0.06 ± 0.05 ppt yr-1. The average Northern Hemisphere (NH) mixing ratio in 1994 was 1.2 ppt rising to a mixing ratio of 10.2 ppt in December 2014. Average annual mixing ratios in the Southern Hemisphere (SH) in 1994 and 2014 were 0.34 and 4.4 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Ggyr-1 in 1994 to a maximum of 54.4 ± 17.1 Ggyr-1 in 2011, declining to 52.5 ± 20.1 Ggyr-1 in 2014 or 7.2 ± 2.8 Tg-CO2 eqyr-1. Analysis of mixing ratio enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia and Europe. Global HFC emissions (so called "bottom up" emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate of "bottom-up" global emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions. [ABSTRACT FROM AUTHOR]

Introduction: The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall. Materials and methods: An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate. Results: The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation. The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery. Conclusions: The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh. [ABSTRACT FROM AUTHOR]

High-frequency, in situ observations from the Advanced Global Atmospheric Gases Experiment (AGAGE), for the period 2003 to 2012, combined with archive flask measurements dating back to 1977, have been used to capture the rapid growth of HFC-143a (CH3CF3) and HFC- 32 (CH2F2) mole fractions and emissions into the atmosphere. Here we report the first in situ global measurements of these two gases. HFC-143a and HFC-32 are the third and sixth most abundant hydrofluorocarbons (HFCs) respectively and they currently make an appreciable contribution to the HFCs in terms of atmospheric radiative forcing (1.7±0.04 and 0.7±0.02mWm-2 in 2012 respectively). In 2012 the global average mole fraction of HFC- 143a was 13.4±0.3 ppt (1σ) in the lower troposphere and its growth rate was 1.4±0.04 ppt yr-1; HFC-32 had a global mean mole fraction of 6.2±0.2 ppt and a growth rate of 1.1±0.04 ppt yr-1 in 2012. The extensive observations presented in this work have been combined with an atmospheric transport model to simulate global atmospheric abundances and derive global emission estimates. It is estimated that 23±3 Gg yr-1 of HFC-143a and 21±11 Gg yr-1 of HFC- 32 were emitted globally in 2012, and the emission rates are estimated to be increasing by 7±5%yr-1 for HFC-143a and 14±11%yr-1 for HFC-32. [ABSTRACT FROM AUTHOR]

High frequency, in situ observations from the Advanced Global Atmospheric Gases Experiment (AGAGE), for the period 2003 to 2012, combined with archive flask measurements dating back to 1977, have been used to capture the rapid growth of HFC-143a (CH3CF3) and HFC-32 (CH2F2) mole fractions and emissions into the atmosphere. Here we report the first in situ global measurements of these two gases. HFC-143a and HFC-32 are the third and sixth most abundant HFCs respectively and they currently make an appreciable contribution to the HFCs in terms of atmospheric radiative forcing (1.7 and 0.7mWm² in 2012, respectively). In 2012 the global average mole fraction of HFC-143a was 13.4±0.3 ppt (1-sigma) in the lower troposphere and its growth rate was 1.4±0.04 pptyr-1; HFC-32 had a global mean mole fraction of 6.2±0.2 ppt and a growth rate of 1.1±0.04 pptyr-1 in 2012. The extensive observations presented in this work have been combined with an atmospheric transport model to simulate global atmospheric abundances and derive global emission estimates. It is estimated that 23±3Ggyr-1 of HFC-143a and 21±11Ggyr-1 of HFC-32 were emitted globally in 2012, and the emission rates are estimated to be increasing 7±5%yr-1 for HFC-143a and 14±11%yr-1 for HFC-32. [ABSTRACT FROM AUTHOR]

The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the highaltitude Jungfraujoch station (Swiss Alps, 46.5° N, 8.0° E, 3580ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν3 band of CF4 centered at 1283 cm-1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals a steady accumulation of the very long-lived CF4 above the Jungfraujoch at mean rates of (1.38±0.11)×1013 molec cm-2 yr-1 from 1989 to 1997, and (0.98±0.02)×1013 molec cm-2 yr-1 from 1998 to 2012, which correspond to linear growth rates of 1.71±0.14 and 1.04±0.02%yr-1 respectively referenced to 1989 and 1998. Related global CF4 anthropogenic emissions required to sustain these mean increases correspond to 15.8±1.3 and 11.1±0.2 Gg yr-1 over the above specified time intervals. Findings reported here are compared and discussed with respect to relevant northern mid-latitude results obtained remotely from space and balloons as well as in situ at the ground, including new gas chromatography mass spectrometry measurements performed at the Jungfraujoch since 2010. [ABSTRACT FROM AUTHOR]

Infrared spectrometry is one of the most important tools in the field of spectroscopic analysis. This is due to the high information content of spectra in the so-called spectroscopic fingerprint region, which enables measurement not only of gases, but also of liquids and solids. Today, infrared spectroscopy is almost completely dominated by Fourier transform infrared (FTIR) spectroscopy. FTIR spectroscopy is able to detect minute quantities in the ppm and ppb ranges, and the respective analyses are now standard tools in science as well as industry. Therefore FTIR spectroscopy should be taught within the standard curriculum at university to physicists and engineers. Here we present respective undergraduate laboratory experiments designed for students at the end of their third year. Experiments deal first with understanding the spectrometer and second with recording and analysing spectra. On the one hand, transmission spectra of gases are treated which relate to environmental analytics (being probably the most prominent and well-known examples), and on the other hand, the focus is on the transmission and reflection spectra of solids. In particular, silicon wafers are studied-as is regularly done in the microelectronics industry-in order to characterize their thickness, oxygen content and phonon modes. [ABSTRACT FROM AUTHOR]

The content of a student lab course is described which deals with characterization of the most important parameters governing the performance of infrared cameras. In detail, the parameters describing the temperature resolution, spatial resolution and time resolution of commercial IR cameras are analysed using simple lab experiments. Understanding the respective performance of the system is the prerequisite for applying infrared thermal imaging to quantitative measurements in physics and technology. [ABSTRACT FROM AUTHOR]

Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the highway tunnel Islisberg (Switzerland). The CO : CO2 ratios, with an average of (4.15 ± 0.34)ppb : ppm, are lower than reported by previous studies, pointing to a reduction in CO emissions from traffic. The 13C in CO2 reflects the isotopic composition of the fuel. 18O in CO2 is slightly depleted compared to the 18O in atmospheric O2, and shows significant variability. In contrast, the δ13C values of CO show that significant fractionation takes place during CO destruction in the catalytic converter. 13C in CO is enriched by 3‰ compared to the 13C in the fuel burnt, while the 18O content is similar to that of atmospheric O2. We compute a fractionation constant of (-2.7 ± 0.7)‰ for 13C during CO destruction. The N2O : CO2 average ratio (1.8 ± 0.2) x 10-2ppb : ppm is significantly lower than in past studies, showing a reduction in N2O emissions likely related to improvements in the catalytic technology. We also observed small CH4 emissions, with an average CH4 : CO2 ratio of (4.6 ± 0.2) x 10-2 ppb : ppm. The O2 : CO2 ratios of (-1.47 ± 0.01) ppm : ppm are very close to the expected, theoretically calculated values. [ABSTRACT FROM AUTHOR]

Liposoluble vitamins are widely analyzed due to their significant antioxidant activity. Quantification by liquid or gas chromatography is often time consuming and requires sample treatments prior to the analysis. Supercritical fluid chromatography (SFC), especially with the developments of new commercial systems, is nowadays considered as a credible alternative to standard chromatography. It provides a reduced acquisition time as well as sensitivity similar to that of liquid chromatography. To illustrate the new capabilities of SFC, six organic compounds related to the vitamin A family, all- trans-retinal, all- trans-retinol, all- trans-retinoic acid, retinyl propionate, retinyl acetate, and all- trans-retinyl palmitate, were analyzed and quantified. The choice of the column chemistry, co-solvent, the linearity and reproducibility of the method, and the matrix effect are discussed in detail. Best separation was finally obtained using a diphenyl column, with an excellent linearity over three orders of magnitude and limits of quantification in the low picomole range. Finally, the method was used for the quantification of retinyl palmitate in a pharmaceutical product with minimal sample preparation. [ABSTRACT FROM AUTHOR]

The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high altitude Jungfraujoch station (Swiss Alps, 46.5°N, 8.0°E, 3580ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the strong v3 band of CF4 centered at 1283 cm−1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals a steady accumulation of the very long-lived CF4 above the Jungfraujoch at mean rates of (1.38±0.11)×1013 molec cm−2 yr−1 from 1989 to 1997, and (0.97±0.02)×1013 molec cm−2 yr−1 from 1998 to 2012, which correspond to linear growth rates of 1.71±0.14 and 1.04±0.02%yr−1, respectively referenced to 1989 and 1998. Related global CF4 emissions required to sustain these mean increases correspond to 15.8±1.3 and 11.1±0.2 Ggyr−1 over the above specified time intervals. Findings reported here are compared and discussed with respect to relevant results obtained remotely from space and balloons as well as in situ on the ground, including new gas chromatography mass spectrometry measurements performed at the Jungfraujoch since 2010. [ABSTRACT FROM AUTHOR]

Copyright of Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article reports on the study that monitors the atmospheric composition change at background site at Jungfraujoch, Switzerland. It shows that the Advanced Global Atmospheric Gases Experiment (AGAGE) method identifies a lower number of observations than from the robust extraction of baseline signal (REBS) technique. It suggests that the selection of the method for identification of background concentrations might have a non-negligible effect on the result.

Information about the surface temperature of the Moon is contained in its emitted thermal infrared (IR) radiation. In this paper, we discuss estimates for surfaces temperatures of the Moon across its disc, as well as the potential to extract quantitatively correct values for the maximum temperatures through measurements with simple hand-held commercial IR cameras. Exemplary measurements reveal suitable conditions and necessary corrections due to atmospheric attenuation. The topic fits well into undergraduate courses on optics or more specifically on IR technologies. [ABSTRACT FROM AUTHOR]

Atmospheric hydrofluorocarbons (HFCs) and per-fluorocarbons (PFCs) were measured in-situ at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for five HFCs and three PFCs showed occasionally high-concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions were 24.5 ppt (parts per trillion, 10-12, molar) for HFC-23, 5.86 ppt for HFC-32, 9.97 ppt for HFC-125, 66.0 ppt for HFC-134a, 9.77 ppt for HFC-152a, 79.1 ppt for CF4, 4.22 ppt for PFC-116, and 0.56 ppt for PFC-218. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere. North-easterly winds were associated with negative contributions to atmospheric HFC and PFC loadings (mixing ratio anomalies weighted by time associated with winds in a given sector), whereas south-westerly advection (urban sector) showed positive loadings. Chinese emissions estimated by a tracer ratio method using carbon monoxide as tracer were 3.6±3.2 kt yr-1 for HFC-23, 4.3±3.6 kt yr-1 for HFC-32, 2.7±2.3 kt yr-1 for HFC-125, 6.0±5.6 kt yr-1 for HFC-134a, 2.0±1.8 kt yr-1 for HFC-152a, 2.4±2.1 kt yr-1 for CF4, 0.27±0.26 kt yr-1 for PFC-116, and 0.061±0.095 kt yr-1 for PFC-218. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of Clean Development Mechanism (CDM) projects that started in 2005. [ABSTRACT FROM AUTHOR]

HCFC-22 (CHClF2, chlorodifluoromethane) is an ozone-depleting substance (ODS) as well as a significant greenhouse gas (GHG). HCFC-22 has been used widely as a refrigerant fluid in cooling and air-conditioning equipment since the 1960s, and it has also served as a traditional substitute for some chlorofluorocarbons (CFCs) controlled under the Montreal Protocol. A low frequency record on tropospheric HCFC-22 since the late 1970s is available from measurements of the Southern Hemisphere Cape Grim Air Archive (CGAA) and a few Northern Hemisphere air samples (mostly from Trinidad Head) using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. Since the 1990s high-frequency, high-precision, in situ HCFC-22 measurements have been collected at these AGAGE stations. Since 1992, the Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected flasks on a weekly basis from remote sites across the globe and analyzed them for a suite of halocarbons including HCFC-22. Additionally, since 2006 flasks have been collected approximately daily at a number of tower sites across the US and analyzed for halo-carbons and other gases at NOAA. All results show an increase in the atmospheric mole fractions of HCFC-22, and recent data show a growth rate of approximately 4% per year, resulting in an increase in the background atmospheric mole fraction by a factor of 1.7 from 1995 to 2009. Using data on HCFC-22 consumption submitted to the United Nations Environment Programme (UNEP), as well as existing bottom-up emission estimates, we first create globally- gridded a priori HCFC-22 emissions over the 15 yr since 1995. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions. Our inversion indicates that the global HCFC-22 emissions have an increasing trend between 1995 and 2009. We further find a surge in HCFC-22 emissions between 2005 and 2009 from developing countries in Asia -- the largest emitting region including China and India. Globally, substantial emissions continue despite production and consumption being phased out in developed countries currently. [ABSTRACT FROM AUTHOR]

Biologically produced molecular hydrogen (H2) is characterised by a very strong depletion in deuterium. Although the biological source to the atmosphere is small compared to photochemical or combustion sources, it makes an important contribution to the global isotope budget of H2. Large uncertainties exist in the quantification of the individual production and degradation processes that contribute to the atmospheric budget, and isotope measurements are a tool to distinguish the contributions from the different sources. Measurements of δD from the various H2 sources are scarce and for biologically produced H2 only very few measurements exist. Here the first systematic study of the isotopic composition of biologically produced H2 is presented. In a first set of experiments, we investigated δD of H2 produced in a biogas plant, covering different treatments of biogas production. In a second set of experiments, we investigated pure cultures of several H2 producing microorganisms such as bacteria or green algae. A Keeling plot analysis provides a robust overall source signature of δD = -712‰ (±13 ‰) for the samples from the biogas reactor (at 38 δC, δDH2O = +73.4 ‰), with a fractionation constant εH2-H2O of -689‰ (±20 ‰) between H2 and the water. The five experiments using pure culture samples from different microorganisms give a mean source signature of δD = -728‰ (±28 ‰), and a fractionation constant εH2-H2O of -711‰(±34 ‰) between H2 and the water. The results confirm the massive deuterium depletion of biologically produced H2 as was predicted by the calculation of the thermodynamic fractionation factors for hydrogen exchange between H2 and water vapour. Systematic errors in the isotope scale are difficult to assess in the absence of international standards for δD of H2. As expected for a thermodynamic equilibrium, the fractionation factor is temperature dependent, but largely independent of the substrates used and the H2 production conditions. The equilibrium fractionation coefficient is positively correlated with temperature and we measured a rate of change of 2.3‰/ δC between 45 δC and 60 δC, which is in general agreement with the theoretical prediction of 1.4‰/ δC. Our best experimental estimate for εH2-H2O at a temperature of 20 δC is -731‰ (±20 ‰) for biologically produced H2. This value is close to the predicted value of -722 ‰, and we suggest using these values in future global H2 isotope budget calculations and models with adjusting to regional temperatures for calculating δD values. [ABSTRACT FROM AUTHOR]

Reflections from glass fronts of curved shape buildings are discussed. Irradiance within the respective caustics can become quite large with regard to regular sun irradiance and can lead to thermal effects. These may cause problems as has been reported for some existing buildings. The phenomena are theoretically discussed for a variety of systems made of segments of cylindrical mirrors using ray tracing models. In particular, six parameters are varied which have an influence on the caustic: building height, building width, radius of curvature, building orientation as well as sun elevation and azimuth angles. In addition, experiments have been performed for various curved shape mirrors and smallscale models of an existing building, for which problems are known to exist. In particular, we investigated the resulting caustic forms visually as well as with infrared cameras to visualize respective thermal effects. Results can explain all features of reported problems. Providing a link to everyday life and modern architecture, the topic is suitable for introducing mirror optics experimentally at school and undergraduate aswell as theoretically at undergraduate and graduate level. [ABSTRACT FROM AUTHOR]

Molecular hydrogen (H2), its stable isotope signature (δD), and the key combustion parameters carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were measured from various combustion processes. H2 in the exhaust of gas and oil-fired heaters and of waste incinerator plants was generally depleted compared to ambient intake air, while CO was significantly elevated. These findings contradict the often assumed co-occurring net H2 and CO emissions in combustion processes and suggest that previous H2 emissions from combustion may have been overestimated when scaled to CO emissions. For the gas and oil-fired heater exhausts, H2 and δD generally decrease with increasing CO2, from ambient values of ∼0.5 ppm and +130‰ to 0.2 ppm and -206‰, respectively. These results are interpreted as a combination of an isotopically light H2 source from fossil fuel combustion and a D/H kinetic isotope fractionation of hydrogen in the advected ambient air during its partial removal during combustion. Diesel exhaust measurements from dynamometer test stand driving cycles show elevated H2 and CO emissions during cold-start and some acceleration phases. While H2 and CO emissions from diesel vehicles are known to be significantly less than those from gasoline vehicles (on a fuel-energy base), we find that their molar H2/CO ratios (median 0.026, interpercentile range 0.12) are also significantly less compared to gasoline vehicle exhaust. Using H2/CO emission ratios, along with CO global emission inventories, we estimate global H2 emissions for 2000, 2005, and 2010. For road transportation (gasoline and diesel), we calculate 8.3±2.2 Tg, 6.0±1.5 Tg, and 3.8±0.94 Tg, respectively, whereas the contribution from diesel vehicles is low (0.9-1.4%). Other fossil fuel emissions are believed to be negligible but H2 emissions from coal combustion are unknown. For residential (domestic) emissions, which are likely dominated by biofuel combustion, emissions for the same years are estimated at 2.7±0.7 Tg, 2.8±0.7 Tg, and 3.0±0.8 Tg, respectively. For biomass burning H2 emissions, we derive a mole fraction ratio ΔH2/ΔCH4 (background mole fractions subtracted) of 3.6 using wildfire emission data from the literature and support these findings with our wood combustion results. When combining this ratio with CH4 emission inventories, the resulting global biomass burning H2 emissions agree well with published global H2 emissions, suggesting that CH4 emissions may be a good proxy for biomass burning H2 emissions. [ABSTRACT FROM AUTHOR]

HCFC-22 (CHClF2, chlorodifluoromethane) is an ozone-depleting substance (ODS) as well as a significant greenhouse gas (GHG). HCFC-22 has been used widely as a refrigerant fluid in cooling and air-conditioning equipment since the 1960s, and it has also served as a traditional substitute for some chlorofluorocarbons (CFCs) controlled under the Montreal Protocol. A low frequency record on tropospheric HCFC-22 since the late 1970s is available from measurements of the Southern Hemisphere Cape Grim Air Archive (CGAA) and a few Northern Hemisphere air samples (mostly from Trinidad Head) using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. Since the 1990s high-frequency, high-precision, in situ HCFC-22 measurements have been collected at these AGAGE stations. Since 1992, the Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected flasks on a weekly basis from remote sites across the globe and analyzed them for a suite of halocarbons including HCFC-22. Additionally, since 2006 flasks have been collected approximately daily at a number of tower sites across the US and analyzed for halocarbons and other gases at NOAA. All results show an increase in the atmospheric mole fractions of HCFC-22, and recent data show a growth rate of approximately 4% per year, resulting in an increase in the background atmospheric mole fraction by a factor of 1.7 from 1995 to 2009. Using data on HCFC-22 consumption submitted to the United Nations Environment Programme (UNEP), as well as an existing bottom-up emissions estimate, we first create globally-gridded a priori HCFC-22 emissions over the 15 yr since 1995. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4) and a Bayesian inverse method to estimate global as well as regional annual emissions. Our inversion indicates that the global HCFC-22 emissions have an increasing trend between 1995 and 2009. We further find a surge in HCFC-22 emissions in 2009 from developing countries in Asia - the largest emitting region including China and India. Globally, substantial emissions continue despite current phase-out of production and consumption in developed countries. [ABSTRACT FROM AUTHOR]

In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) have been conducted at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for 5 HFCs and 4 PFCs periodically showed high concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218 and PFC-318 were 24.5, 5.86, 9.97, 66.0, 9.77, 79.1, 4.22, 0.56, 1.28 ppt (parts per trillion, 10-12, molar), respectively. The background mixing ratios for the compounds at SDZ are consistent with 10 those obtained at mid to high latitude sites in the Northern Hemisphere, except for HFC- 32 and PFC-318 for which background mixing ratios were not reported in recent years. All HFCs and PFCs show positive trends at rates of 0.7, 1.4, 1.6, 4.1, 1.1, 0.43, 0.05, 0.01, 0.04 pptyr-1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC- 116, PFC-218 and PFC-318, respectively. North-easterly winds were connected with small contributions to atmospheric HFCs and PFCs loadings, whereas south-westerly advection (urban sector) showed increased loadings. Chinese emissions were estimated by a tracer ratio method using CO as tracer with rather well known emissions. The emissions, as derived from our measurement period, were 4.4±0.7, 6.9±0.9, 2.5±0.3, 9.0±1.3, 2.2±0.4, 2.1±0.3, 0.24±0.06, 0.07±0.04, 0.45±0.09 kt yr-1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218, and PFC- 318, respectively. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of the Clean Development Mechanism (CDM) project that started in 2005. [ABSTRACT FROM AUTHOR]

A Kalman-filter based inverse emission estimation method for long-lived trace gases is presented for use in conjunction with a Lagrangian particle dispersion model like FLEXPART. The sequential nature of the approach allows tracing slow seasonal and interannual changes rather than estimating a single period-mean emission field. Other important features include the estimation of a slowly varying concentration background at each measurement station, the possibility to constrain the solution to non-negative emissions, the quantification of uncertainties, the consideration of temporal correlations in the residuals, and the applicability to potentially large inversion problems. The method is first demonstrated for a set of synthetic observations created from a prescribed emission field with different levels of (correlated) noise, which closely mimics true observations. It is then applied to real observations of the three halocarbons HFC-125, HFC-152a and HCFC-141b at the remote research stations Jungfraujoch and Mace Head for the quantification of emissions in Western European countries from 2006 to 2010. Estimated HFC-125 emissions are mostly consistent with national totals reported to UNFCCC in the framework of the Kyoto Protocol and show a generally increasing trend over the considered period. Results for HFC-152a are much more variable with estimated emissions being both higher and lower than reported emissions in different countries. The highest emissions of the order of 700-800 Mg yr-1 are estimated for Italy, which so far does not report HFC-152a emissions. Emissions of HCFC-141b show a continuing strong decrease as expected due to its controls in developed countries under the Montreal Protocol. Emissions from France, however, were still rather large, in the range of 700-1000 Mg yr-1 in the years 2006 and 2007 but strongly declined thereafter. [ABSTRACT FROM AUTHOR]

Molecular hydrogen (H2), its stable isotope signature (δD), and the key combustion parameters carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were measured from various combustion processes. H2 in the exhaust of gas and oil-fired heaters and of waste incinerator plants was generally depleted compared to ambient intake air, while CO was significantly elevated. These findings contradict the often assumed co-occurring net H2 and CO emissions in combustion processes and suggest that previous H2 emissions from combustion may have been overestimated when scaled to CO emissions. For the heater exhausts, H2 and δD generally decrease with increasing fuel-to-air ratio, from ambient values of ~0.5 ppm and +130‰ to 0.2 ppm and -206‰, respectively. These results are interpreted as a combination of an isotopically light H2 source from fossil fuel combustion and a D/H kinetic isotope fractionation of hydrogen in the advected ambient air during its partial removal during combustion. Diesel exhaust measurements from dynamometer test stand driving cycles show elevated H2 and CO emissions during cold-start and some acceleration phases. Their molar H2/CO ratios are <0.25, significantly smaller than those for gasoline combustion. Using H2/CO emission ratios, along with CO global emission inventories, we estimate global H2 emissions for 2000, 2005, and 2010. For road transportation (gasoline and diesel), we calculate 8.6±2.1 Tg, 6.3±1.5 Tg, and 4.1±1.0 Tg, respectively, whereas the contribution from diesel vehicles has increased from 5% to 8% over this time. Other fossil fuel emissions are believed to be negligible but H2 emissions from coal combustion are unknown. For residential (domestic) emissions, which are likely dominated by biofuel combustion, emissions for the same years are estimated at 2.7±0.7 Tg, 2.8±0.7 Tg, and 3.0±0.8 Tg, respectively. Our wood combustion measurements are combined with results from the literature to calculate biomass burning emissions. For these estimates, we propose a molar H2/CH4 ratio of 3.3, when using CH4 emission inventories. When using this approach, our resulting global biomass burning H2 emissions agree well with published results, suggesting that CH4 emissions may be a good proxy for H2 emissions. [ABSTRACT FROM AUTHOR]

Biologically produced molecular hydrogen (H2) is characterized by a very strong depletion in deuterium. Although the biological source to the atmosphere is small compared to photochemical or combustion sources, it makes an important contribution to the global isotope budget of molecular hydrogen (H2). Large uncertainties exist in the quantification of the individual production and degradation processes that contribute to the atmospheric budget, and isotope measurements are a tool to distinguish the contributions from the different sources. Measurements of δD from the various H2 sources are scarce and for biologically produced H2 only very few measurements exist. Here the first systematic study of the isotopic composition of biologically produced H2 is presented. We investigated δD of H2 produced in a biogas plant, covering different treatments of biogas production, and from several H2 producing microorganisms such as bacteria or green algae. A Keeling plot analysis provides a robust overall source sig15 nature of δD = -712‰ (±13 ‰) for the samples from the biogas reactor (at 38 °C, Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed = 73.4 ‰), with a fractionation constant Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed of -689‰ (±20 ‰). The pure culture samples from different microorganisms give a mean source signature of δD =-728‰ (± 39 ‰), and a fractionation constant Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed -711‰ (± 45 ‰) between H2 and the water, respectively. The results confirm the massive deuterium depletion of biologically produced H2 as was predicted by calculation of the thermodynamic fractionation factors for hydrogen exchange between H2 and water vapor. As expected for a thermodynamic equilibrium, the fractionation factor is largely independent of the substrates used and the H2 production conditions. The predicted equilibrium fractionation coefficient is positively correlated with temperature and we measured a change of 2.2 ‰/°C between 45 °C and 60 °C. This is in general agreement with the theoretical predictions. [ABSTRACT FROM AUTHOR]

A Kalman-filter based inverse emission estimation method for long-lived trace gases is presented for use in conjunction with a Lagrangian particle dispersion model like FLEXPART. The sequential nature of the approach allows tracing slow seasonal and interannual changes rather than estimating a single period-mean emission field. Other important features include the estimation of a slowly varying concentration background at each measurement station, the possibility to constrain the solution to non-negative emissions, the quantification of uncertainties, the consideration of temporal correlations in the residuals, and the applicability to potentially large inversion problems. The method is first demonstrated for a set of synthetic observations created from a prescribed emission field with different levels of (correlated) noise, which closely mimics true observations. It is then applied to real observations of the three halocarbons HFC-125, HFC-152a and HCFC-141b at the remote research stations Jungfraujoch and Mace Head for the quantification of emissions in Western European countries from 2006 to 2010. Estimated HFC-125 emissions are mostly consistent with national totals reported to the Kyoto protocol and show a generally increasing trend over the considered period. Results for HFC-152a are much more variable with estimated emissions being both higher and lower in different countries. The highest emissions of the order of 1000Mg yr-1 are estimated for Italy which so far does not report HFC-152a emissions. Emissions of HCFC-141b show a continuing strong decrease as expected due to its ban under the Montreal Protocol. Emissions from France, however, were still rather large (near 1000Mg yr-1) in the years 2006 and 2007 but strongly declined thereafter. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the recent tropospheric molecular hydrogen (H2) budget with a particular focus on soil uptake and European surface emissions. A variational inversion scheme is combined with observations from the RAMCES and EUROHYDROS atmospheric networks which include continuous measurements performed between mid-2006 and mid-2009. Net H surface flux, then deposition velocity and surface emissions and finally, deposition velocity, biomass burning, anthropogenic and N2 fixation-related emissions were simultaneously inverted in several scenarios. These scenarios have focused on the sensibility of the soil uptake value to different spatio-temporal distributions. The range of variations of these diverse inversion sets generate an estimate of the uncertainty for each term of the H2 budget. The net H2 flux per region (High Northern Hemisphere, Tropics and High Southern Hemisphere) varies between -8 and +8Tgyr-1. The best inversion in terms of fit to the observations combines updated prior surface emissions and a soil deposition velocity map that is based on bottom-up and top-down estimations. Our estimate of global H2 soil uptake is -59±9 Tg yr -1. Forty per cent of this uptake is located in the High Northern Hemisphere and 55% is located in the Tropics. In terms of surface emissions, seasonality is mainly driven by biomass burning emissions. The inferred European anthropogenic emissions are consistent with independent H2 emissions estimated using a H2/CO mass ratio of 0.034 and CO emissions within the range of their respective uncertainties. Additional constraints, such as isotopic measurements would be needed to infer a more robust partition of H2 sources and sinks. [ABSTRACT FROM AUTHOR]