bluuebunny/crossref_metadata_2025 huggingface dataset:
Uniaxial-strain tuning method in study of iron-based superconductors
Authors: Li Chun-Yi , Mo Zi-Ye , Lu Xing-Ye ,   Center for Advanced Quantum Studies, School of Physics and Astronomy, Beijing Normal University, Beijing 100875, China
Published: September 2024

In the study of quantum materials, introducing pressure and strain that can change lattice parameters and symmetry is an effective experimental method for manipulating the electronic properties of the system. In measurements under hydrostatic pressure or in-plane epitaxial strain, the changes in lattice parameters will lead to significant changes in the electronic structure, thereby triggering off novel quantum phenomena and phase transitions. By comparison, the in-plane uniaxial strain, which has been widely employed in recent years, not only changes lattice parameters, but also directly destroys and controls the symmetry of the system, thereby affecting the electronic ordering state and even collective excitation of the system. This article provides a comprehensive overview of the basic concepts of uniaxial strain, the development of experimental methods, and some research progress in using these methods to regulate superconductivity and electronic nematicity in iron-based superconductors. This review contains six sections. Section 1 focuses on a genetral introduction for the uniaxial strain techque and the arrangement of this paper. Section 2 is devoted to the basic concepts and formulas related to elastic moduli and the decomposition of uniaxial strain into irreducible symmetric channels under D4h point group. Section 3 gives iron-based superconductors (FeSCs) and discusses the uniaxial-pressure detwinning method and related research progress. Section 4 introduces the establishment of the elastoresistance as a probe of the nematic susceptibility and discusses the key researches in this direction. Section 5 describes the research progress of the effects of uniaxial strain on superconductivity and nematicity. In sections 4 and 5, key experimental techniques, such as elastoresistance, are discussed in detail. Section 6 extends the discussion to several types of quantum materials suitable for uniaxial-strain tuning method beyond the FeSCs. Finally, we provide a brief summary and outlook on the uniaxial strain tuning technique. Overall, this review article provides valuable resources for the beginners in the field of FeSC and those who are interested in using uniaxial strain to modulate the electronic properties of quantum materials. By summarizing recent advancements and experimental techniques, this review hopes to inspire further research and innovation in studying electronic materials under uniaxial strain.
White matter structural bases for phase accuracy during tapping synchronization
Authors: Garcia-Saldivar Pamela , de León Cynthia , Mendez Salcido Felipe A , Concha Luis , Merchant Hugo
Published: September 2024

We determined the intersubject association between the rhythmic entrainment abilities of human subjects during a synchronization-continuation tapping task (SCT) and the macro- and microstructural properties of their superficial (SWM) and deep (DWM) white matter. Diffusion-weighted images were obtained from 32 subjects who performed the SCT with auditory or visual metronomes and five tempos ranging from 550 to 950 ms. We developed a method to determine the density of short-range fibers that run underneath the cortical mantle, interconnecting nearby cortical regions (U-fibers). Notably, individual differences in the density of U-fibers in the right audiomotor system were correlated with the degree of phase accuracy between the stimuli and taps across subjects. These correlations were specific to the synchronization epoch with auditory metronomes and tempos around 1.5 Hz. In addition, a significant association was found between phase accuracy and the density and bundle diameter of the corpus callosum (CC), forming an interval-selective map where short and long intervals were behaviorally correlated with the anterior and posterior portions of the CC. These findings suggest that the structural properties of the SWM and DWM in the audiomotor system support the tapping synchronization abilities of subjects, as cortical U-fiber density is linked to the preferred tapping tempo and the bundle properties of the CC define an interval-selective topography.
Association Between Oral Health and Gastric Cancer in Korean Adults
Authors: Lee Sang Hoon , Cho Hyunseok , Park Sung Chul , Kim Sang Hoon , Kim Seung Young , Jeon Han Jo , Lee Sang Pyo , Choe Younghee ,   the Metabolism, Obesity, and Nutrition Research Group of the Korean College of Helicobacter and Upper Gastrointestinal Research
Published: September 2024

Objectives: Poor oral hygiene is known to be associated with gastric cancer, but this remains controversial. In this study, we investigated the association between oral health and gastric cancer in Korean adults using data from the Korea National Health and Nutrition Examination Survey. Methods: We analyzed data of 79501 patients with gastric cancer and 41856805 individuals without gastric cancer (control group) using the 7th and 8th Korea National Health and Nutrition Examination Survey (2016–2019) records. Layer and colony variables and weights were used for the complex sample design. We performed logistic regression analysis of complex samples to analyze factors that affect gastric cancer development. Results: Patients with gastric cancer were older and had a higher prevalence of hypertension, hyperlipidemia, and diabetes and a higher rate of current smoking and alcohol consumption than individuals without gastric cancer (p<0.001). Regarding oral health-related factors, the prevalence of very uncomfortable chewing difficulty was significantly higher in patients with gastric cancer (14.4% vs. 3.6%, p<0.001). On multivariate analysis of factors associated with gastric cancer, chewing difficulty showed the highest odds ratio (5.351, 95% confidence interval 2.128–8.982). Patients with very uncomfortable chewing difficulty had high rates of previous dental nerve treatment, gum disease treatment, tooth extraction or intraoral surgery, and prosthetic repair (p<0.001). Conclusions: Oral health-related chewing difficulties were associated with gastric cancer, which may be attributable to poor oral hygiene and degradation of oral microbiota. Patients at risk of gastric cancer warrant timely medical interventions to address their oral health and chewing difficulties.
Vulnerable Employment among Rural Youth in Karnataka State: A Study of Sustainable Livelihood Capitals
Authors: Gunashekhar H. , Sreenivasulu M. , Manjunatha B. , Patil Dayananda , Prem S. Manju , Damodhara G. N. , Kiran N. R. , B N Priyanka , J. Harishkumar
Published: September 2024

Agriculture in India sustains over half the population, faces a critical challenge as its youth disengage from this sector due to low incomes and high risks, which impedes agricultural reform and competitiveness in the global food market. In 2021, a study was conducted in Karnataka's Mandya and Ramanagara districts, focusing on assessing the vulnerable employment among 120 randomly selected rural youth in agriculture through constructing a vulnerable employment index.  The study revealed that the overall composite vulnerable employment index was 0.63, with human capital being the highest contributor to vulnerable employment (0.80), followed by financial capital (0.78), physical capital (0.68), natural capital (0.63), and social capital (0.57). Notably, 67.50 per cent of surveyed youth face moderate to highly vulnerable employment, primarily due to deficiencies in human capital (72.50%), financial capital (72.50%), natural capital (79.16%), and social capital (77.50%). However, there is a glimmer of hope in the relatively lower vulnerability in physical capital (48.33%). This research highlighted the urgent need to address vulnerable employment among rural youth in agricultural endeavour by investing in relevant skills training and education, providing access to financial resources, ensuring sustainable management of natural capital, and fostering strong social capital through mentorship programs and community engagement.
Effect of Socio-economic Status on the Dietary Behaviours of Rural Women in Kurnool District of Andhra Pradesh, India
Authors: Prashant  , N. R. Chaithra , V. Sangeetha , Singh Premlata , V. Lenin , P. Venkatesh , T. N. Srinatha
Published: September 2024

The dietary behavior of rural women in India is a topic of significant importance and intrigue, reflecting a complex interplay of cultural traditions, socioeconomic constraints, and evolving dietary patterns. India, with its vast and diverse rural landscape, is home to a substantial proportion of its population, and women play a pivotal role in shaping the dietary habits of their households. Looking at the importance of the above-mentioned issues, the study was conducted in the Kurnool district of Andhra Pradesh to know the dietary behavior of rural women. Dietary behavior is operationalized as the variety and quantity of food (that includes cereals, pulses, vegetables, fruits and other foods) consumed in 30 days. 24hrs recall method developed by the Food and Agriculture Organization (FAO) was used for daily food consumption analysis. The multiple regression analysis technique was attempted to show the effect of socio-economic variables on the consumption of different food items. The results indicate that per-capita consumption of all the food items except the other vegetables was less than the Recommended Dietary Allowance (RDA). Cereals were the major contributor to the food security of the people and the respondents’ average consumption of cereals was 284 g/day, whereas the RDA is 400g/day. The autonomous consumption in the case of vegetables is 70.84 grams per day, consumption in the case of pulses is 26.653 grams per day and consumption of fruits by women in the study area was found to be 19.3 grams per day.
Exploring Guava and Neem Extracts as Therapeutic Options for Methicillin-Resistant Staphylococcus aureus (MRSA) in Africa
Authors: Efoli-Bam Victory Kokolae , Oyaniyi Jumoke , Odanibeh David , Josephson Chukwuma Junior , Mobolanle Banwo Faridah , Onyema Chikwesiri Emmanuel , Ojobor Jane-Frances Chinenye , Udensi Chukwuma Great , Azubuike Eberechukwu Osinachi , Nwokafor Chibuzo Valentine
Published: September 2024

MRSA is a virulent strain of antibiotic-resistant Staphylococcus aureus and a principal cause of disease prevalence and death rates. MRSA's resistance to traditional antibiotics makes it a rather crucial threat to public health. Plants with traditional medicinal uses, including A. indica and P. guajava, may provide an alternate means of treatment. This review explores the antibacterial capabilities of Psidium guajava (guava) and Azadirachta indica (neem) against MRSA by evaluating data from multiple investigations carried out in Africa. Study shows that A. indica and P. guajava extracts may have strong antibacterial action; multiple studies show that they can prevent growth of MRSA and stop formation of biofilms. Despite the extracts' lower efficacy when compared to modern antibiotics, reports suggest that plant extracts could serve as a novel approach to effectively tackle antimicrobial resistance due to their enhanced synergistic efficacy when combined with other extracts. This is all achieved with low toxicity, hence the call for more research to investigate this thoroughly. Moreover, the socio-economic consequences of applying these easily accessible and reasonably priced plant-based remedies in environments with limited resources were determined to be advantageous to Africa. The review highlights the necessity of conducting more thorough clinical trials and standardizing procedures to validate the therapeutic potential of these plants against MRSA.
Impact of Land Use Patterns on Soil Invertebrate Abundance and Diversity at GKVK Campus, Bengaluru, India
Authors: Godavari  , Hiremath Kavya M
Published: September 2024

At the University of Agricultural Sciences, GKVK, Bengaluru, a study analyzed soil invertebrate macrofauna across four land use types: roadside soil, forest ecosystem, paddy ecosystem, and botanical garden. Sampling involved 12 units across these categories using Berlese-Tullgren funnels. A total of 55 individuals were collected, with ants and spiders found in all land use types, but earthworms and Collembola were absent from paddy ecosystems. Forests showed the highest macrofauna abundance (49.09%), followed by botanical gardens (29.09%). Spiders (45.4%) and Collembola (23.63%) were the most abundant, indicating that natural environments support  richer macrofauna communities. Intensive agriculture alters these communities' abundance and diversity.
Probiotics as Potential Therapeutics for Managing COVID-19: Mechanisms and Implications
Authors: Chaudhary Aditya , Saharan Baljeet Singh , Tyagi Swati , Goyal Chhaya , Mandal Neelam Kumari , Kumar Ramesh , Duhan Joginder Singh , Badoni Prerana
Published: September 2024

The transmission of viruses between different animal species and humans can lead to the emergence of new infectious diseases with unpredictable pathogenic potential. COVID-19, caused by SARS-CoV-2, has had a significant impact on human health and the global economy. The disease is characterized by symptoms such as dry cough, fatigue, muscle pain, fever, shortness of breath, gastrointestinal discomfort, nausea, vomiting, and runny nose. With limited vaccine accessibility for individuals between the ages of 18 and 45, exploring alternative therapies is essential. This paper aims to elucidate the preventive and supportive therapeutic role of probiotics in managing COVID-19. It discusses the specific mechanisms by which probiotics regulate the balance of gut microbes, promote gut homeostasis, and exert regulatory effects on the mucosal immune system, the gut-lung axis, and potential antiviral processes.
Dehydration‐induced porosity waves and episodic tremor and slip
Authors: Skarbek Rob M. , Rempel Alan W.
Published: January 2016

Episodic tremor and slip (ETS) along the subduction interface takes place where there is abundant evidence for elevated, near‐lithostatic pore pressures, at sufficiently great depths (30–45 km) that chemical dehydration reactions must act as their dominant source. We simulate fluid and heat flow while tracking the location of a vertically oriented, one‐dimensional column of material as it subducts through the slow slip and tremor zone. The material in the column is transformed through a pressure‐dependent and temperature‐dependent dehydration reaction that we describe with a generalized nonlinear kinetic rate law. Column deformation is largely dominated by viscous creep, with a closure rate that depends linearly on porosity. This behavior causes the dehydration reaction to generate traveling porosity waves that transport increased fluid pressures within the slow slip region. To explore the possibility that the observed periodicity of slow slip and tremor in subduction zones can be explained by the migration of such porosity waves, we derive a dispersion relation that accurately describes our numerical results. We also obtain an expression for how the thickness of the dehydrating layer is expected to vary as a function of the parameters in the reaction rate law. Although the amplitudes of pore pressure perturbations rival those that are produced by known external forcings (e.g., tides or passing surface waves), our analysis suggests that given reasonable estimates of rock viscosity, permeabilities in the range
to
are required for porosity wave trains to form at periods comparable to those of slow slip and tremor.
Laboratory observations of time‐dependent frictional strengthening and stress relaxation in natural and synthetic fault gouges
Authors: Carpenter B. M. , Ikari M. J. , Marone C.
Published: January 2016

Interseismic recovery of fault strength (healing) following earthquake failure is a fundamental requirement of the seismic cycle and likely plays a key role in determining the stability and slip behavior of tectonic faults. We report on laboratory measurements of time‐ and slip‐dependent frictional strengthening for natural and synthetic gouges to evaluate the role of mineralogy in frictional strengthening. We performed slide‐hold‐slide (SHS) shearing experiments on nine natural fault gouges and eight synthetic gouges at conditions of 20 MPa normal stress, 100% relative humidity (RH), large shear strain (~15), and room temperature. Phyllosilicate‐rich rocks show the lowest rates of frictional strengthening. Samples rich in quartz and feldspar exhibit intermediate rates of frictional strengthening, and calcite‐rich gouges show the largest values. Our results show that (1) the rates of frictional strengthening and creep relaxation scale with frictional strength, (2) phyllosilicate‐rich fault gouges have low strength and healing characteristics that promote stable, aseismic creep, (3) most natural fault gouges exhibit intermediate rates of frictional strengthening, consistent with a broad range of fault slip behaviors, and (4) calcite‐rich fault rocks show the highest rates of frictional strengthening, low values of dilation upon reshear, and high frictional strengths, all of which would promote seismogenic behavior.
In situ stress magnitudes at the toe of the Nankai Trough Accretionary Prism, offshore Shikoku Island, Japan
Authors: Huffman K. A. , Saffer D. M.
Published: January 2016

Quantifying the orientation and magnitude of tectonic stresses is essential toward understanding deformation and faulting in subduction zones. However, constraints on in situ horizontal stress magnitudes (Shmin and SHmax) are rare. We estimate Shmin and SHmax at Ocean Drilling Program Site 808 at the toe of the Nankai accretionary prism offshore Japan, using coupled constraints from (1) the width of wellbore breakouts together with estimates of rock strength and a model describing stress redistribution at the borehole wall and (2) limits on regional differential stress defined by failure on preexisting faults. Our analysis extends from 175 to 915 m below seafloor (mbsf) and spans the active frontal thrust. For an upper bound on rock unconfined compressive strength (UCS) and assuming hydrostatic formation pore pressure, Shmin and SHmax (referenced to the seafloor) increase from 6.5 MPa at 175 mbsf to 17.4 MPa at 915 mbsf, with the stress state gradually transitioning from a thrust or strike‐slip faulting regime above 800 mbsf to a normal faulting regime below. For cases with higher formation pore pressure, horizontal stresses are slightly lower but follow a similar pattern. We show that estimated Shmin and SHmax are strongly dependent on UCS, breakout width, and friction coefficient, all of which are characterized by uncertainty. Our results suggest that the prism is near thrust failure in the upper ~300 mbsf, but far from failure below. This may be reconciled with active thrusting if thrust faults are locally weaker than the surrounding rock or if SHmax fluctuates during the seismic cycle.
Elasticity of plagioclase feldspars
Authors: Brown J. Michael , Angel Ross J. , Ross Nancy L.
Published: January 2016

Elastic properties are reported for eight plagioclase feldspars that span compositions from albite (NaSi3AlO8) to anorthite (CaSi2Al2O8). Surface acoustic wave velocities measured using Impulsive Stimulated Light Scattering and compliance sums from high‐pressure X‐ray compression studies accurately determine all 21 components of the elasticity tensor for these triclinic minerals. The overall pattern of elasticity and the changes in individual elastic components with composition can be rationalized on the basis of the evolution of crystal structures and chemistry across this solid‐solution join. All plagioclase feldspars have high elastic anisotropy; a* (the direction perpendicular to the b and c axes) is the softest direction by a factor of 3 in albite. From albite to anorthite the stiffness of this direction undergoes the greatest change, increasing twofold. Small discontinuities in the elastic components, inferred to occur between the three plagioclase phases with distinct symmetry (
,
, and
), appear consistent with the nature of the underlying conformation of the framework‐linked tetrahedra and the associated structural changes. Measured body wave velocities of plagioclase‐rich rocks, reported over the last five decades, are consistent with calculated Hill‐averaged velocities using the current moduli. This confirms long‐standing speculation that previously reported elastic moduli for plagioclase feldspars are systematically in error. The current results provide greater assurance that the seismic structure of the middle and lower crusts can be accurately estimated on the basis of specified mineral modes, chemistry, and fabric.
Sea level budget in the Bay of Bengal (2002–2014) from GRACE and altimetry
Authors: Kusche J. , Uebbing B. , Rietbroek R. , Shum C. K. , Khan Z. H.
Published: January 2016

Sea level rise is perceived as a major threat to the densely populated coast of the Bay of Bengal. Addressing future rise requires understanding the present‐day sea level budget. Using a novel method and data from the Gravity Recovery and Climate Experiment (GRACE) satellite, we partition altimetric sea level rise (6.1 mm/a over 2002–2014) into mass and steric components. We find that current mass trends in the Bay of Bengal are slightly above global mean, while steric trends appear much larger: 2.2–3.1 mm/a if we disregard a residual required to close the budget, and 4.3–4.6 mm/a if, as an upper bound, we attribute this residual entirely to steric expansion. Our method differs from published approaches in that it explains altimetry and GRACE data in a least squares inversion, while mass anomalies are parameterized through gravitationally self‐consistent fingerprints, and steric expansion through EOFs. We validate our estimates by comparing to Argo and modeling for the Indian Ocean, and by comparing total water storage change (TWSC) for the Ganges and Brahmaputra basins to the conventional GRACE approach. We find good agreement for TWSC, and reasonable agreement for steric heights, depending on the ocean region and Argo product. We ascribe differences to weaknesses of the Argo data, but we also find the inversion to be to some extent sensitive with respect to the EOFs. Finally, combining our estimates with CMIP5‐simulations, we estimate that Bay of Bengal absolute sea level may rise for additional 37 cm under the RCP4.5 scenario and 40 cm under RCP8.5 until 2050, with respect to 2005.
Large vertical gradient of reactive nitrogen oxides in the boundary layer: Modeling analysis of DISCOVER‐AQ 2011 observations
Authors: Zhang Yuzhong , Wang Yuhang , Chen Gao , Smeltzer Charles , Crawford James , Olson Jennifer , Szykman James , Weinheimer Andrew J. , Knapp David J. , Montzka Denise D. , Wisthaler Armin , Mikoviny Tomas , Fried Alan , Diskin Glenn
Published: January 2016

An often used assumption in air pollution studies is a well‐mixed boundary layer (BL), where pollutants are evenly distributed. Because of the difficulty in obtaining vertically resolved measurements, the validity of the assumption has not been thoroughly evaluated. In this study, we use more than 200 vertical profiles observed in the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER‐AQ) aircraft campaign in July 2011 to examine the vertical distributions of pollutants over the Washington‐Baltimore area. While many long‐lived species are well mixed in daytime, the observed average vertical profile of NOx shows a large negative gradient with increasing altitude in the BL. Our analysis suggests that the magnitude of the NOx gradient is highly sensitive to atmospheric stability. We investigate how parameterizations of the BL and land‐surface processes impact vertical profiles in a 1‐D chemical transport model, using three BL schemes (Asymmetric Convective Model version 2 (ACM2), Yonsei University (YSU), and Mellor‐Yamada‐Janjic (MYJ)) and two land‐surface schemes (Noah and Rapid Update Cycle (RUC)). The model reasonably reproduces the median vertical profiles of NOx under different BL stability conditions within 30% of observations, classified based on potential temperature gradient and BL height. Comparisons with NOx observations for individual vertical profiles reveal that while YSU performs better in the turbulent and deep BL case, in general, ACM2 (RMSE = 2.0 ppbv) outperforms YSU (RMSE = 2.5 ppbv) and MYJ (RMSE = 2.2 ppbv). Results also indicate that the land‐surface schemes in the Weather Research and Forecasting (WRF) model have a small impact on the NOx gradient. Using model simulations, we analyze the impact of BL NOx gradient on the calculation of the ozone production rate and satellite NO2 retrieval. We show that using surface measurements and the well‐mixed BL assumption causes a ~45% high bias in the estimated BL ozone production rate and that the variability of NO2 vertical profiles is responsible for 5–10% variability in the retrieved NO2 tropospheric vertical columns.
Changes in atmospheric carbonyl sulfide over the last 54,000 years inferred from measurements in Antarctic ice cores
Authors: Aydin M. , Campbell J. E. , Fudge T. J. , Cuffey K. M. , Nicewonger M. R. , Verhulst K. R. , Saltzman E. S.
Published: January 2016

We measured carbonyl sulfide (COS) in air extracted from ice core samples from the West Antarctic Ice Sheet (WAIS) Divide, Antarctica, with the deepest sample dated to 54,300 years before present. These are the first ice core COS measurements spanning the Last Glacial Maximum (LGM), the last glacial/interglacial transition, and the early Holocene. The WAIS Divide measurements from the LGM and the last transition are the first COS measurements in air extracted from full clathrate (bubble‐free) ice. This study also includes new COS measurements from Taylor Dome, Antarctica, including some in bubbly glacial ice that are concurrent with the WAIS Divide data from clathrate glacial ice. COS hydrolyzes in ice core air bubbles, and the recovery of an atmospheric record requires correcting for this loss. The data presented here suggest that the in situ hydrolysis of COS is significantly slower in clathrate ice than in bubbly ice. The clathrate ice measurements are corrected for the hydrolysis loss during the time spent as bubbly ice only. The corrected WAIS Divide record indicates that atmospheric COS was 250–300 parts per trillion (ppt) during the LGM and declined by 80–100 ppt during the last glacial/interglacial transition to a minimum of 160–210 ppt at the beginning of the Holocene. This decline was likely caused by an increase in the gross primary productivity of terrestrial plants, with a possible contribution from a reduction in ocean sources. COS levels were above 300 ppt in the late Holocene, indicating that large changes in the COS biogeochemical cycle occurred during the Holocene.
Stability analysis of ecomorphodynamic equations
Authors: Bärenbold F. , Crouzy B. , Perona P.
Published: January 2016

In order to shed light on the influence of riverbed vegetation on river morphodynamics, we perform a linear stability analysis on a minimal model of vegetation dynamics coupled with classical one‐ and two‐dimensional Saint‐Venant‐Exner equations of morphodynamics. Vegetation is modeled as a density field of rigid, nonsubmerged cylinders and affects flow via a roughness change. Furthermore, vegetation is assumed to develop following a logistic dependence and may be uprooted by flow. First, we perform the stability analysis of the reduced one‐dimensional framework. As a result of the competitive interaction between vegetation growth and removal through uprooting, we find a domain in the parameter space where originally straight rivers are unstable toward periodic longitudinal patterns. For realistic values of the sediment transport parameter, the dominant longitudinal wavelength is determined by the parameters of the vegetation model. Bed topography is found to adjust to the spatial pattern fixed by vegetation. Subsequently, the stability analysis is repeated for the two‐dimensional framework, where the system may evolve toward alternate or multiple bars. On a fixed bed, we find instability toward alternate bars due to flow‐vegetation interaction, but no multiple bars. Both alternate and multiple bars are present on a movable, vegetated bed. Finally, we find that the addition of vegetation to a previously unvegetated riverbed favors instability toward alternate bars and thus the development of a single course rather than braiding.
Cooling lubricants and other complex hydrocarbon mixtures, immiscible with water – aerosols and vapours [Air Monitoring Methods, 2015]
Authors: Breuer D. , Blaskowitz M. , Pannwitz K.‐H. , Parlar H. , Hartwig A. ,   MAK Commission
Published: January 2016

The measurement method is validated for the determination of droplet/vapour mixtures of water immiscible cooling lubricants (CL) and other complex hydrocarbon mixtures (CHM) in workplace air averaged over the sampling period after personal or stationary sampling. The method is validated for a concentration range from 0.5 mg/m
3
to 200 mg/m
3
. Sampling is performed by drawing a defined volume of air through an inhalable dust‐vapour sampling system (
G
esamtstaub‐
G
as‐
P
robenahmesystem – GGP) using a suitable pump. During sampling airborne particles are deposited onto a glass fibre filter and the corresponding vapours are adsorbed onto XAD‐2 resin. The flow rate is adjusted to 3.5 L/min. For sample preparation the collected analytes are eluted from the filter and XAD‐2 with tetrachloroethene. The quantitative determination is carried out by means of the integral absorbance in the infrared wavelength range of 3000‐2800 cm
‐1
. The limit of quantification (LOQ) is 0.5 mg/m
3
for an air sample volume of 420 litres. The expanded uncertainty for these parameters is between 20.6 and 25.3%.
Method for the determination of quartz and cristobalite [Air Monitoring Methods, 2015]
Authors: Fricke H.‐H. , Mattenklott M. , Parlar H. , Hartwig A. ,   MAK Commission
Published: January 2016

The analytical method is validated for the determination of quartz and cristobalite in workplace air averaged over the sampling period after personal or stationary sampling. Sampling is performed by drawing a defined volume of air through a membrane filter located in the sampling head of the sampling device using a suitable pump. The respirable dust fraction is collected during sampling as stipulated in EN 481. Examples of sampling systems that have proved successful are PM 4F, VC 25F, FSP‐10, FSP‐BIA, and MPG II. Gravimetric determination of the respirable dust fraction is initially carried out, and then the concentration of quartz and cristobalite are determined in the respirable dust fraction with the aid of Fourier Transform Infrared Spectroscopy (FTIR). The determination is based on the blank value method and the method of calibration function in the lower measurement range according to DIN 32645. For the used sampling system FSP‐10 respectively PM‐4F the limit of quantification (LOQ) is 0.025 respectively 0.004 mg/m
3
for a sampling period of two hours (air sample volume 120 litres / 8 m
3
) and 0.006 respectively 0.001 mg/m
3
for a sampling period of eight hours (air sample volume 480 litres / 32 m
3
).
Method for the determination of aromatic amines [Air Monitoring Methods, 2015]
Authors: Krämer W. , Parlar H. , Hartwig A. ,   MAK Commission
Published: January 2016

The analytical method is validated for the determination of aromatic amines, such as aniline, 4‐ethoxyaniline, methoxyanilines, methylanilines and dimethylanilines in the air of working areas averaged over the sampling period after personal or stationary sampling. Sampling is performed by drawing a defined volume of air through a glass fibre filter impregnated with sulphuric acid using a suitable pump. The filter is located in a total dust sampling system (Gesamt‐Staub‐Probenahme – GSP). The flow rate is adjusted to 1 L/min whereby the definition of the inhalable dust is fulfilled by this volumetric flow according to EN 481. For sample preparation the collected aromatic amines are desorbed from the filter with a mixture of acetonitrile/ammonia solution. The sample solution is analysed by means of gas chromatography‐mass spectrometry (GC‐MS). Quantitative determination is based on a 10‐point calibration according to DIN 32645 using 4‐propylaniline as internal standard. The limits of quantification (LOQ) are between 0.003 and 0.26 mg/m
3
for an air sample volume of 240 litres. The expanded uncertainty for these parameters is between 21 and 23%, depending on the aromatic amine and concentration.
Method for the determination of arsenic and its compounds [Air Monitoring Methods, 2015]
Authors: Hahn J.‐U. , Parlar H. , Hartwig A. ,   MAK Commission
Published: January 2016

The analytical method is validated for the determination of arsenic and its compounds in the air of workplaces averaged over the sampling period after personal or stationary sampling. Sampling is performed by drawing a defined volume of air through a membrane filter located in the sampling head of a total dust sampling system (
G
esamt‐
S
taub‐
P
robenahme – GSP) using a suitable pump. The flow rate is adjusted to 10 L/min whereby the definition of the inhalable dust is fulfilled by this volumetric flow according to EN 481. After acid digestion the sample solution is analysed by means of graphite furnace atomic absorption spectrometry (GFAAS). Calibration solutions are prepared with the help of an autosampler by dilution with a constant injection volume. The determination of the limit of quantification (LOQ) is based on the blank value method and the method of the calibration function in the lower measurement range according to DIN 32645. The measurement range is between 0.25 and 3.3 µg/m
3
for an air sample volume of 1.2 m
3
. The LOQ is 0.25 µg/m
3
for an air sample volume of 1.2 m
3
.The expanded uncertainty of 26% was calculated for a validation concentration of 1.7 µg/m
3
. The sample preparation procedure described here was checked with elemental arsenic and arsenic(III) oxide.
Determination and evaluation of chemical contamination of indoor workplace atmospheres (excluding activities involving hazardous substances) [Air Monitoring Methods, 2015]
Authors: Breuer D. , Sagunski H. , Ball M. , Hebisch R. , von Hahn N. , Lahrz T. , Nitz G. , Pannwitz K.‐H. , Rosenberger W. , Parlar H. , Hartwig A. ,   MAK Commission
Published: January 2016

This report provides comprehensive information on the assessment of possible chemical factors in indoor working areas and on the conditions for the measurement of all relevant substances in indoor areas. The indoor workplace measurement strategy is based on the guidelines on ventilation of indoor workplaces given inTechnical Rules for Workplaces (ASR A3.6). Initially an indoor workplace is intensely ventilated (3 minutes (winter) to 10 minutes (summer)) and subsequently windows and doors are closed. Measurement is carried out one hour after closure of doors and windows. The measurement results obtained under these conditions (terms of use conditions) are suitable for comparison with guide values. Should these values be exceeded, then measures according to the recommendations issued by the German Committee on Indoor Guide Values should be taken. The effectiveness of these measures must be checked. If it is necessary to obtain additional information on sources in the work space, then measurement should be carried out under equilibrium conditions. For this purpose the space is thoroughly ventilated and subsequently kept closed for at least 8 hours (overnight as a general rule). Sampling is then carried out in the unventilated room. This measurement strategy was used to derive reference values (e. g. DGUV reference values) for indoor workplaces. It is advisable to carry out both measurements in series. Measurement under equilibrium conditions is carried out first, followed by measurement under terms of use conditions. In addition, the report gives guidance how to calculate the TVOC value und a detailed checklist is included which is specifically adapted to the requirements presented by indoor working areas.
Trimethylbenzene (all isomers) [BAT Value Documentation, 2009]
Authors: Kraus T. , Schaller K.H. , Knecht U. , Csanády G. , Drexler H. , Hartwig A. ,   MAK Commission
Published: January 2016

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated the biological tolerance value at the work place (BAT value) for trimethylbenzene, considering the sum of dimethylbenzoic acids in urine to characterize the internal exposure. The evaluation is based on the relationship between external and internal exposure to the present MAK value of 100 mg/m
3
.

The BAT value was derived on the basis of the inhalation chamber studies of Kostrzewski et al. (1997) and Knecht et al. (2000, 2003). For an air concentration at the level of the MAK value of 100 mg/m
3
, Kostrzewski et al. (1997) found a mean sum concentration of dimethylbenzoic acid metabolites of 450 mg/g creatinine, Knecht et al. (2000) of 417 mg/g creatinine, and for an air concentration of 90 mg/m
3
269 mg/g creatinine (Knecht et al. 2003). Only Knecht et al. (2000, 2003) cited a 95th percentile and during the exposure, a defined physical activity was carried out, so that the conditions were more realistic compared with the study by Kostrzewski et al. (1997).

Altogether, the mean value was about 400 mg total dimethylbenzoic acids per gram creatinine. Considering the 95th percentiles in the studies of Knecht et al. (2000, 2003), a BAT‐value of 600 mg total dimethylbenzoic acids (after hydrolysis)/g creatinine was evaluated.

Samples should be taken at the end of exposure or end of shift, and, for long‐term exposures, after several shifts. Hydrolysis of the urine samples is necessary for the analytical determination of the metabolites.
N‐Methyl‐2‐pyrrolidone [BAT Value Documentation, 2009]
Authors: Bader M. , Wrbitzky R. , Drexler H. , Hartwig A. ,   MAK Commission
Published: January 2016

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated a biological tolerance value at the work place (BAT value) for N‐methyl pyrrolidone (NMP), considering 5‐Hydroxy‐N‐methyl‐2‐pyrrolidone (5‐HNMP) in urine to characterize the internal exposure.

A BAT value for 5‐HNMP in urine can at present not be derived from effect parameters, but only on the basis of the correlation to the MAK value.

According to Bader et al. (2007), an 8‐hour exposure to NMP at the level of the MAK value of 82 mg/m3with an activity of 75W for one hour during the exposure interval results in a 5‐HNMP concentration of 153 mg/g creatinine (186 mg/l).

According to Åkesson and Jönsson (2000) the expected 5‐HNMP concentration after 8 hours exposure to 82 mg NMP/m3is 183 mg/g creatinine or 220 mg/l assuming a mean creatinine concentration of 1.2 g/l, performed at rest. Possibly, the differences of the corresponding results by Bader et al. (2007) can be attributed to the influence of an additional dermal absorption.

On the basis of the results by Bader et al. (2007), a BAT value of 150 mg 5‐Hydroxy‐N‐methyl‐2‐pyrrolidone/l urine corresponding to the MAK value of 82 mg/m3has been derived. Sampling time is at the end of exposure.
Mercapturic acids of 2‐chloroprene, epichlorohydrin, and 1,3‐butadiene in urine [Biomonitoring Methods, 2015]
Authors: Eckert E. , Göen T. , Hartwig A. ,   MAK Commission
Published: January 2016

The analytical method permits simultaneous determination of the mercapturic acid of epichlorohydrin i.e. N‐acetyl‐S‐(3‐chloro‐2‐hydroxypropyl) cysteine (CHPMA) and of four mercapturic acids of 2‐chloroprene in urine: N‐acetyl‐S‐(4‐chloro‐3‐oxobutyl) cysteine (Cl‐MA I), N‐acetyl‐S‐(3‐chloro‐2‐hydroxy‐3‐butenyl) cysteine (Cl‐MA III), N‐acetyl‐S‐(4‐hydroxy‐3‐oxobutyl) cysteine (HOBMA) and N‐acetyl‐S‐(3,4‐dihydroxybutyl) cysteine (DHBMA). The mercapturic acids HOBMA and DHBMA are also formed after exposure to 1,3‐butadiene.

For determination, the urine samples are buffered to pH 2.5, spiked with isotopelabeled internal standards (d3‐CHPMA, d3‐Cl‐MA I, d3‐Cl‐MA III, d3‐HOBMA and d7‐DHBMA), processed using online solid phase extraction (online SPE) and LC–MS/MS. For that purpose the analytes are enriched on a C18 pre‐concentration column [RAM (Restricted Access Material) phase]. Subsequently, the analytes are transferred in backflush mode from the RAM phase to the analytical column, separated chromatographically and finally subjected to tandem mass spectrometric detection. Calibration is carried out using standard solutions in pooled urine which are processed and analyzed in the same way as the samples to be analyzed.
Creatinine in urine [Biomonitoring Methods, 2015]
Authors: Bader M. , Netz‐Piepenbrink S. , Göen T. , Hartwig A. ,   MAK Commission
Published: January 2016

The analytical procedure described here permits the determination of creatinine, the degradation product of creatine or creatine phosphate, in urine using high‐performance liquid chromatography. For that purpose, urine samples are diluted with ultrapure water at a ratio of 1 : 5 and then analyzed isocratically using HPLC‐UV. Aqueous standards are used for calibration.
N‐Methylformamide and N‐methylacetamide in urine [Biomonitoring Methods, 2015]
Authors: Will W. , Göen T. , Hartwig A. ,   MAK Commission
Published: January 2016

The present method allows for the determination of the main metabolites of N,N‐dimethylformamide and N,N‐dimethylacetamide in urine: HMMF, NMF, HMMA and NMA, respectively. HMMF and HMMA readily decompose thermally to form N‐methylformamide (NMF) or N‐methylacetamide (NMA) and formaldehyde. Prior to sample injection, thermolysis is carried out for 2 hours at 120°C in order to transform the metabolites completely into the target analytes NMF and NMA. The urine samples are then diluted with ethanol and analyzed using GC–MS. Thus, the sum of HMMF and NMF (DMF metabolites) and the sum of HMMA and NMA (DMA metabolites), respectively, are detected by this procedure.
n‐, sec‐, iso‐, tert‐Butylamin [MAK Value Documentation in German language, 2016]
Authors: Meischner V. , Laube B. , Bartsch R. , Hartwig A. ,   MAK Commission
Published: January 2016

MAK Value Documentation for n‐, sec‐, iso‐, tert‐Butylamine

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) of n‐, sec‐, iso‐ and tert‐butylamine, considering local and systemic toxicity as well as developmental toxicity. Daily exposure of rats to n‐butylamine for 14 days resulted in inflammation of respiratory epithelium at 17 ml/m
3
. Since 2014, the Commission uses an empirical approach to set MAK values for substances with critical effects on the upper respiratory tract or the eyes, which would result in lowering the MAK‐value for n‐butylamine. However, workers reported no irritation at 1 to 2 ml n‐Butylamine/m
3
. Therefore, the MAK value of 2 ml/m
3
is confirmed, also for sec‐ and iso‐butylamine due to similar structure, pKa and RD
50
values. With tert‐butylamine the LOAEC of 66 ml/m
3
in rats in a 13‐week study resulted in nasal tissue inflammation and liver weight increase. Following the empirical approach, the same MAK value of 2 ml/m
3
is set for tert‐butylamine. As local effects might be or are critical, Peak Limitation Category I and an excursion factor of 2 and momentary value of 5 ml/m
3
is assigned for all butylamine isomers. Developmental toxicity studies with n‐butylamine show that damage to the embryo or foetus is unlikely if the MAK value is observed and thus n‐butylamine is assigned to Pregnancy Risk Group C. Due to the lack of developmental toxicity studies, sec‐, iso‐ and tert‐butylamine are assigned to Pregnancy Risk Group D.
Phosphorylchlorid [MAK Value Documentation in German language, 2016]
Authors: Kreis P. , Bartsch R. , van Thriel C. , Brüning T. , Hartwig A. ,   MAK Commission
Published: January 2016

MAK Value Documentation for Phosphorus oxychloride

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) of phosphorus oxychloride of 0.2 ml/m
3
, considering the endpoints local and systemic toxicity as well as developmental toxicity. Available publications are described in detail. Phosphorus oxychloride is corrosive to eyes and skin and hydrolyses in water to hydrogen chloride and phosphoric acid, similar to phosphorus trichloride. There is not enough data for phosphorus oxychloride to set a MAK value because valid inhalation studies with repeated exposure are missing. Therefore, the MAK value of phosphorus oxychloride is derived by using a read‐across to phosphorus trichloride for which a MAK value of 0.1 ml/m
3
has been set based on a 28‐day inhalation study. Considering the fivefold higher NOAEC of phosphorus trichloride for sensory irritation in volunteers and rats the MAK value for phosphorus oxychloride is lowered accordingly to 0.02 ml/m
3
. The assignment to Peak Limitation Category I, because local effects are critical, and the excursion factor of 1 are confirmed. The assignment to Pregnancy Risk Group C is retained as damage to the embryo or foetus is unlikely when the MAK value is observed.
Tetrahydronaphthalene [MAK Value Documentations, 2013]
Authors: Jahnke G. , Schwabe R. , Hartwig A. ,   MAK Commission
Published: January 2016

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated tetrahydronaphthalene to derive a maximum concentration at the workplace (MAK value), considering all toxicity endpoints. Available unpublished study reports and publications are described in detail. In animal studies, the target organs of the toxicity of tetrahydronaphthalene are the liver and kidneys and, after inhalation, also the respiratory tract. The relative kidney weights of female rats were increased at tetrahydronaphthalene concentrations of 15 ml/m
3
and above in both a 14‐week study and a 14‐day study. The NOAEC was 7.5 ml/m
3
in both studies, and 15 ml/m
3
for effects on the olfactory epithelium in the 14‐week study. In mice, NOAEC of 15 and 30 ml/m
3
were obtained for female and male animals, respectively, after exposure for 14 weeks. From the NOAEC of 15 ml/m
3
for effects in the nose of rats and the NOAEC of 7.5 ml/m
3
for increased relative kidney weights in female rats, a MAK value of 2 ml/m
3
is derived. Both systemic and local effects lead to the same MAK value and no data for local effects or the half‐life are available for humans. The classification in Peak Limitation Category I is therefore based on the lower default excursion factor of 1 as compared to 2 for Peak Limitation Category II. The NOAEL for developmental toxicity and maternal toxicity in rats was 45 mg/kg body weight and day. The difference between the MAK value and the calculated NAEC for developmental toxicity together with the difference between the MAK value and the calculated LAEC for developmental toxicity is, in view of the low severity of the findings and the simultaneous occurrence of maternal toxicity, sufficiently large. Thus, damage to the embryo or foetus is unlikely when the MAK value is observed and the substance is classified in Pregnancy Risk Group C. Tetrahydronaphthalene is not genotoxic and not carcinogenic in 2‐year inhalation studies in rats and mice. Tetrahydronaphthalene is not a contact sensitizer in guinea pigs and no clear results for sensitization in humans are available. Skin contact is not expected to contribute significantly to systemic toxicity.