Coefficient Measurements Research Articles

Measurement of nonlinear refraction and absorption coefficient in BaGa2GeSe6 crystal

The coefficients of nonlinear absorption and nonlinear refraction of the quaternary barium chalcogenide crystal BaGa2GeSe6 at a wavelength corresponding to half the band gap, as well as their dependence on the pulse repetition rate and peak on-axis irradiance, were measured for the first time. The third-order nonlinear optical properties were studied using the single-beam Z-scan technique. An Nd: YLF laser at 1.053 μm with a pulse duration of approximately 5.2 ns was used as a radiation source. In addition, a thermal Z-scan was carried out to investigate thermal lensing in the BaGa2GeSe6 crystal, employing a continuous wave Nd: YAG laser at 1064 nm. These studies represent an important step in comprehending the nonlinear optical properties of barium chalcogenide crystals and their behavior at different pulse intensities. The results might be significant for the modelling and design of mid-infrared optical systems.

A Numerical simulation method for analyzing 1H spin diffusion NMR for Multicomponent and multiphase polymer systems

A numerical simulation method, namely, SDNMR-WEBFIT, is reported for simulating proton spin diffusion NMR based on the Levenberg-Marquardt algorithm and a pseudo-2D diffusion model. This method is used for the precise quantification of dynamics heterogeneity of the interphase within multiphase polymer systems. The numerical simulation method provides measurements of spin-lattice relaxation time (T1), proton density (ρH), lamellar thickness (d), and spin diffusion coefficient (D) for each component. The pseudo-2D diffusion model is employed to simulate the proton spin diffusion build-up/decay curves, simultaneously calculating the lateral fraction of island-like structures (x-ratio). Such approach was successfully applied to various polymer systems, such as semi-crystalline polymer (Poly(ε-caprolactone), PCL), block copolymers (Styrene-butadiene-styrene triblock copolymer, SBS), and plasticized semi-polymers (Polvinyl alcohol, PVA).

The measurement of complex modal coefficients of a superposed vortex beam based on intensity sampling methods

In recent years, extracting information from superposed vortex beams has been a topic of intense study. In this paper, complex coefficients of various superpositions are measured in both simulation and experiment by proposing and implementing four different sampling methods. Superposed vortex beams are experimentally generated using a digital micromirror device, and recorded on a 2 f optical imaging setup. To extract both amplitude and phase values of modal coefficients, a single intensity frame of the beam is sampled in the form of concentric circles, sectors, random circles, and random squares. Considering just specified parts of the intensity instead of the whole to sample the pattern increases the speed of the modal coefficient extraction. Besides, a linear set of coherent equations is solved, and achievements are compared together. As a consequence, measuring both the amplitude and phase values of coefficients simultaneously can pave the way to enable high-capacity optical communication which is carried out in this research with better than 99% and 96% accuracy, respectively.

Effect of orientation and hardness of rubber tread block on the friction coefficient under glycerol lubrication and its underlying mechanisms

This study examines the influence of orientation and hardness of rubber tread blocks on friction under glycerol lubrication, focusing on negative fluid pressure. Measurements of fluid pressure, film thickness, and friction coefficient were conducted at the contact interface. Results showed that when tread blocks aligned parallel to the sliding direction, the friction coefficient increased by 57–191 %, attributed to either reduced film thickness or enlarged real contact area from greater negative fluid pressure. Conversely, with a perpendicular orientation, decreased hardness led to increased friction, due to thinner fluid films from enhanced negative pressure.

Exploring electrical transport in thin film and bulk thermoelectric materials with an automated Seebeck coefficient and resistivity measurement platform

Accurate assessment of electrical properties, particularly the Seebeck coefficient and electrical resistivity, is critical in thermoelectric energy harvesting research, which involves converting thermal energy into electricity. This study presents an innovative automated system designed for the simultaneous measurement of the Seebeck coefficient and electrical resistivity as a function of temperature in both film and bulk samples. The system exhibits high precision across a wide range of electrical resistance, from milli Ohm (mΩ) to giga Ohm (GΩ). Furthermore, and in contrast with commercial systems, it provides excellent flexibility in accommodating samples with diverse lateral dimensions and thicknesses, ranging from a few millimetres to several centimetres. The measurement principle is based on analysing the current–voltage (I-V) characteristic of the samples. To ensure seamless monitoring and control of the measurement process, a user-friendly and adaptable Graphical User Interface (GUI) is integrated into the system, enhancing its overall user-friendliness and convenience.

Cytoplasmic fluidization contributes to breaking spore dormancy in fission yeast

The cytoplasm is a complex, crowded environment that influences myriad cellular processes including protein folding and metabolic reactions. Recent studies have suggested that changes in the biophysical properties of the cytoplasm play a key role in cellular homeostasis and adaptation. However, it still remains unclear how cells control their cytoplasmic properties in response to environmental cues. Here, we used fission yeast spores as a model system of dormant cells to elucidate the mechanisms underlying regulation of the cytoplasmic properties. By tracking fluorescent tracer particles, we found that particle mobility decreased in spores compared to vegetative cells and rapidly increased at the onset of dormancy breaking upon glucose addition. This cytoplasmic fluidization depended on glucose-sensing via the cyclic adenosine monophosphate-protein kinase A pathway. PKA activation led to trehalose degradation through trehalase Ntp1, thereby increasing particle mobility as the amount of trehalose decreased. In contrast, the rapid cytoplasmic fluidization did not require de novo protein synthesis, cytoskeletal dynamics, or cell volume increase. Furthermore, the measurement of diffusion coefficients with tracer particles of different sizes suggests that the spore cytoplasm impedes the movement of larger protein complexes (40 to 150 nm) such as ribosomes, while allowing free diffusion of smaller molecules (~3 nm) such as second messengers and signaling proteins. Our experiments have thus uncovered a series of signaling events that enable cells to quickly fluidize the cytoplasm at the onset of dormancy breaking.

Qualitative and quantitative MRI analysis of alveolar soft part sarcoma: correlation with histological grade and Ki-67 expression

ObjectiveTo investigate the correlation between MRI findings and histological features for preoperative prediction of histological grading and Ki-67 expression level in alveolar soft part sarcoma (ASPS).MethodsA retrospective analysis was conducted on 63 ASPS patients (Jan 2017–May 2023). All patients underwent 3.0-T MRI examinations, including conventional sequences, dynamic contrast-enhanced scans with time-intensity curve analysis, and diffusion-weighted imaging with apparent diffusion coefficient (ADC) measurements. Patients were divided into low-grade (histological Grade I) and high-grade (histological Grade II/III) groups based on pathology. Immunohistochemistry was used to assess Ki-67 expression levels in ASPS. Statistical analysis included chi-square tests, Wilcoxon rank-sum test, binary logistic regression analysis, Spearman correlation analysis, and receiver operating characteristic curve analysis of various observational data.ResultsThere were 29 low-grade and 34 high-grade patients (26 males and 37 females) and a wide age range (5–68 years). Distant metastasis, tumor enhancement characteristics, and ADC values were independent predictors of high-grade ASPS. High-grade ASPS had lower ADC values (p = 0.002), with an area under the curve (AUC), sensitivity, and specificity of 0.723, 79.4%, and 58.6%, respectively, for high-grade prediction. There was a negative correlation between ADC values and Ki-67 expression (r = −0.526; p < 0.001). When the cut-off value of ADC was 0.997 × 10−3 mm²/s, the AUC, sensitivity, and specificity for predicting high Ki-67 expression were 0.805, 65.6%, and 83.9%, respectively.ConclusionQualitative and quantitative MRI parameters are valuable for predicting histological grading and Ki-67 expression levels in ASPS.Critical relevance statementThis study will help provide a more nuanced understanding of ASPS and guide personalized treatment strategies.Key PointsThere is limited research on assessing ASPS prognosis through MRI.Metastasis, enhancement, and ADC correlated with histological grade; ADC related to Ki-67 expression.MRI provides clinicians with valuable information on ASPS grading and proliferation activity.Graphical

Physical properties of rutile-TiO2 Nanoparticles and effect on PVA/SiO2 hybrid films synthesized by sol-gel method

We use an ab-initio approach to analyze the structural, electronic band structure, and thermoelectric properties of titanium dioxide (TiO2 in rutile phase), and we then use rutile-TiO2 nanoparticles to determine its effects on sol-gel-produced polyvinyl alcohol/silicon dioxide (PVA/SiO2) hybrid films. The synthesis of hybrid films involved the incorporation of 1 % rutile-TiO2 nanoparticles in the PVA/SiO2 matrix. The thermoelectric properties of the resulting hybrid films were characterized by Seebeck coefficient measurements, as well as electrical and thermal conductivities. The synthesis of PVA/SiO2/Nano-TiO2 films was accomplished with success. The chemical bonds have amply demonstrated that the PVA backbone is connected to the (SiO2-TiO2) network. TGA testing indicates that hybrid films are more resistant to higher temperatures than pure PVA films. SiO2 nanoparticles reveal more effective loading to improve dielectric characteristics compared to TiO2. The best results are obtained in cases of mechanical, thermal and electrical insulation when both nanofillers are integrated into the polymer matrix. The findings show that the thermoelectric performance of PVA/SiO2 hybrid films is improved by the addition of (1 %) rutile-TiO2 nanoparticles in the rutile phase. This study provides insights into the potential applications of rutile-TiO2 nanoparticles in enhancing the thermoelectric properties of hybrid materials and opens up avenues for further research in this area, and contributes to the growing body of knowledge on enhancing the thermoelectric properties of materials by incorporating rutile-TiO2 nanoparticles into hybrid films synthesized by the sol-gel method.

Absolute rate coefficient measurements of the reactions of vibrationally cold HD+ and H3+ ions with neutral C atoms

Ion-neutral reactions are driving the formation of small molecules in the gas phase of interstellar clouds, where hydrogen molecules and their ions are by far the most important collision partners for any species in the astrochemical network. Here we present absolute rate coefficient measurements for the reactions HD++C→CH+/CD++D/H and H3++C→CH+/CH2++H2/H obtained using a recently commissioned ion-neutral collision setup at the Cryogenic Storage Ring. Our measurements with vibrationally cold ions result in significantly higher rate coefficients when compared with previous studies using internally excited ions, bringing them in better agreement with classical capture theories. Moreover, we have performed detailed quasiclassical trajectory (QCT) calculations for the HD++C reaction, using new potential energy surfaces. Our experimental results and the QCT calculations show very good agreement for the absolute cross section of the reactions, as well as for the isotope effect. These results have great potential relevance for the chemistry of the interstellar medium and the onset of organic chemistry in space. Published by the American Physical Society 2024

Interfacial Behavior of Biodegradable Poly(lactic-co-glycolic acid)-Pluronic F127 Nanoparticles and Its Impact on Pickering Emulsion Stability.

Biodegradable nanoparticle-based emulsions exhibit immense potential in various applications, particularly in the pharmaceutical, cosmetic, and food industries. This study delves into the intricate interfacial behavior of Pluronic F127 modified poly(lactic-co-glycolic acid) (PLGA-F127) nanoparticles, a crucial determinant of their ability to stabilize Pickering emulsions. Employing a combination of Langmuir balance, surface tension, and diffusion coefficient measurements, we investigate the interfacial dynamics of PLGA-F127 nanoparticles under varying temperature and ionic strength conditions. Theoretical calculations are employed to elucidate the underlying mechanisms governing these phenomena. Our findings reveal a profound influence of temperature-dependent Pluronic layer behavior and electrostatic and steric interactions on the interfacial dynamics. Nonlinear changes in surface tension are observed, reflecting the interplay of these factors. Particle aggregation is found to be prevalent at elevated temperatures and ionic strengths, compromising the stability and emulsification efficiency of the formed emulsions. This work provides insights into the rational design of stable and efficient biodegradable nanoparticle-based Pickering emulsions, broadening their potential applications in various fields.

Comparison of scanning aerosol lidar and in situ measurements of aerosol physical properties and boundary layer heights

Abstract. The spatiotemporal distribution of aerosol particles in the atmosphere has a great impact on radiative transfer, clouds, and air quality. Modern remote sensing methods, as well as airborne in situ measurements by unpiloted aerial vehicles (UAV) or balloons, are suitable tools to improve our understanding of the role of aerosol particles in the atmosphere. To validate the measurement capabilities of three relatively new measurement systems and to bridge the gaps that are often encountered between remote sensing and in situ observation, as well as to investigate aerosol particles in and above the boundary layer, we conducted two measurement campaigns and collected a comprehensive dataset employing a scanning aerosol lidar, a balloon-borne radiosonde with the Compact Optical Backscatter Aerosol Detector (COBALD), an optical particle counter (OPC) on a UAV, and a comprehensive set of ground-based instruments. The extinction coefficients calculated from near-ground-level aerosol size distributions measured in situ are well correlated with those retrieved from lidar measurements, with a slope of 1.037 ± 0.015 and a Pearson correlation coefficient of 0.878, respectively. Vertical profiles measured by an OPC-N3 on a UAV show similar vertical particle distributions and boundary layer heights to lidar measurements. However, the sensor, OPC-N3, shows a larger variability in the aerosol backscatter coefficient measurements, with a Pearson correlation coefficient of only 0.241. In contrast, the COBALD data from a balloon flight are well correlated with lidar-derived backscatter data from the near-ground level up to the stratosphere, with a slope of 1.063 ± 0.016 and a Pearson correlation coefficient of 0.925, respectively. This consistency between lidar and COBALD data reflects the good data quality of both methods and proves that lidar can provide reliable and spatial distributions of aerosol particles with high spatial and temporal resolutions. This study shows that the scanning lidar has the capability to retrieve backscatter coefficients near the ground level (from 25 to 50 m above ground level) when it conducts horizontal measurement, which is not possible for vertically pointing lidar. These near-ground-level retrievals compare well with ground-level in situ measurements. In addition, in situ measurements on the balloon and UAV validated the scanning lidar retrievals within and above the boundary layer. The scanning aerosol lidar allows us to measure aerosol particle distributions and profiles from the ground level to the stratosphere with an accuracy equal to or better than in situ measurements and with a similar spatial resolution.

Brain network topology and its cognitive impact in adult glioma survivors

Structural brain network topology can be altered in case of a brain tumor, due to both the tumor itself and its treatment. In this study, we explored the role of structural whole-brain and nodal network metrics and their association with cognitive functioning. Fifty WHO grade 2–3 adult glioma survivors (> 1-year post-therapy) and 50 matched healthy controls underwent a cognitive assessment, covering six cognitive domains. Raw cognitive assessment scores were transformed into w-scores, corrected for age and education. Furthermore, based on multi-shell diffusion-weighted MRI, whole-brain tractography was performed to create weighted graphs and to estimate whole-brain and nodal graph metrics. Hubs were defined based on nodal strength, betweenness centrality, clustering coefficient and shortest path length in healthy controls. Significant differences in these metrics between patients and controls were tested for the hub nodes (i.e. n = 12) and non-hub nodes (i.e. n = 30) in two mixed-design ANOVAs. Group differences in whole-brain graph measures were explored using Mann–Whitney U tests. Graph metrics that significantly differed were ultimately correlated with the cognitive domain-specific w-scores. Bonferroni correction was applied to correct for multiple testing. In survivors, the bilateral putamen were significantly less frequently observed as a hub (pbonf < 0.001). These nodes’ assortativity values were positively correlated with attention (r(90) > 0.573, pbonf < 0.001), and proxy IQ (r(90) > 0.794, pbonf < 0.001). Attention and proxy IQ were significantly more often correlated with assortativity of hubs compared to non-hubs (pbonf < 0.001). Finally, the whole-brain graph measures of clustering coefficient (r = 0.685), global (r = 0.570) and local efficiency (r = 0.500) only correlated with proxy IQ (pbonf < 0.001). This study demonstrated potential reorganization of hubs in glioma survivors. Assortativity of these hubs was specifically associated with cognitive functioning, which could be important to consider in future modeling of cognitive outcomes and risk classification in glioma survivors.

Operational risk management – Measurement and evaluation of friction coefficients for geotextile sandbags for flood protection

AbstractThe present work focuses on the friction coefficient for various geotextile sandbag structures especially dikes under different conditions. Based on the review of existing investigations there are several gaps to close. Former investigations do not include the whole scope of needed surfaces and conditions. Especially the friction coefficients for polypropylene and even for jute as material mainly used for small geotextile sandbags are not fully available. Additionally, the influence of the surface moisture is not consequently investigated, particularly for jute. Due to this, eleven test series (three with sandbag on sandbag configuration and eight with sandbag on ground surface) with 780 single readings are finalized. In comparison to former studies there are results for surface combinations of good harmonization and those with differences. A comparison of the earlier studies already shows different results Summarized it can be stated that the presented results are representative friction coefficients for calculation of realistic sandbag structures e. g., sandbag dikes or spring cascades.

Measurement of Diffusion Coefficients and Assessment of Atomic Mobilities in HCP Mg-Ag-Sn Alloys

Reliable thermodynamic and kinetic databases are essential for designing and developing novel magnesium (Mg) alloys for elevated-temperature applications in the automotive and aerospace industries. This study investigated diffusion behaviors of HCP Mg-Ag-Sn alloys by four sets of three diffusion couples annealed at 450, 500, and 550 °C, respectively. Interdiffusion and impurity diffusion coefficients at the three annealing temperatures were extracted using the forward-simulation method. The determined diffusion coefficients, combined with prior results in the literature, were then used to assess atomic mobilities for the HCP phase of the Mg-Ag-Sn system. This assessment was conducted using the DICTRA and the TCMG5 thermodynamic database within the Thermo-Calc software. Comprehensive comparisons between calculated and experimental diffusion coefficients yielded an excellent agreement. The atomic mobilities were also further validated by appropriate predictions of concentration profiles and diffusion paths observed in independent diffusion couple experiments performed at 525 °C for 18 hrs. It has been found that the addition of Sn and Ag both increase the diffusivity of Ag in HCP Mg and Sn in HCP Mg in the stable temperature range of HCP Mg, respectively. This improved understanding of the kinetics in the Mg-Ag-Sn ternary system is essential for controlling diffusion-dependent properties such as coarsening and, therefore, the mechanical properties of Mg-Ag-Sn alloys at elevated temperatures.

Sound absorption coefficient measurement and analysis for multisection perforation microperforated panel

Sound absorption coefficient measurement and analysis for multisection perforation microperforated panel

Modelling and measurements of heat transfer coefficient in classroom experiments

Thermal insulation of buildings is important because it has both ecological and social impacts. Most often, it is characterized by the so-called U-value. Heat transfer through walls includes conduction, convection, and thermal radiation. This leads to complex measurements and calculations for assessing the effectiveness of different insulating materials, and the usual methods are not suitable for classroom experiments. We propose a simple method for measuring the U-values of varied materials used in everyday life that can be performed in the classroom. It is based on measuring the temperature inside and outside a box, and the power, released by a resistance coil inside the box.

Nonlinear Schrödinger equation for integrated photonics

The foundations of nonlinear optics are revisited, and the formalism is applied to waveguide modes. The effects of loss and dispersion are included rigorously along with the vectorial nature of the modes, and a full derivation of a new version of the nonlinear Schrödinger (NLS) equation is presented. This leads to more general expressions for the group index, for the group-index dispersion (GVD), and for the Kerr coefficient. These quantities are essential for the design of waveguides suitable for, e.g., the generation of optical frequency combs and all-optical switches. Examples are given using the silicon nitride material platform. Specifically, values are extracted for the coefficients of the chi-3 tensor based on measurements of Kerr coefficients and mode simulations.

Structural, optical, luminescence spectroscopy and radiation shielding properties of Eu3+:borophosphotellurite glasses

Recently much effort is being paid to study the rare earth ions in multi component glass formers as they exhibit high enhancement in the efficiency of luminescence properties. In this direction, the present study focuses on the preparation and analysis of novel glass batches with composition of (in mol %) BPTCZEu: 40B2O3+20P2O5+15TeO2+ 10CaO+(15−x)ZnO + xEu2O3, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5. The important spectroscopic techniques such as optical absorption, luminescence, excitation and decay curves are taken to analyse the BPTCZEu glasses. Luminescence spectrum of BPTCZEu comprise of emission from excited (5D0) to the lower multiplets (7FJ (J = 0−4)), among these, 5D0 → 7F2 (red luminescence) at 612 nm found to be very intense. Judd−Ofelt characteristics, Ω2, Ω4 and Ω6, were derived from different constraints. To know the site symmetry around Eu3+, the fluorescence intensity ratio of 5D0 → 7F2 vs. 5D0 → 7F1 were analysed. Exciting 7F0 → 5L6 and monitoring 5D0 → 7F2, the lifetime of 5D0 level is determined to be 2 ms which is independent of Eu3+ content. The colour coordinates for all the Eu3+ concentrations are estimated to fall in the reddish−orange region. Theoretical radiation shielding results showed that substituting Eu2O3 for ZnO in the glasses lowers photon number that can pass via the material, enhancing the glass system's trend to shield high energy radiation. These stimulated results are compared with experimental measurements of mass attenuation coefficient with respect to energy up to 662 KeV using Cs−137 source. All these findings obtained from title glasses are compared and discussed with respect to reported Eu3+:glasses and no systematic variation has been noticed either with single, bi− or multi−component glass formers and therefore needs further systematic work to relate Eu−radiation−ligand interaction.

The efficiency of micellar solubilization of naphthalene from aqueous solutions using rhamnolipid as a biological surfactant according to NMR diffusometry.

The micellar solubilization of naphthalene from its saturated aqueous solutions using the biosurfactant rhamnolipid was studied. Using the NMR diffusion method, selective measurements of the self-diffusion coefficients of molecules of all components of the solution-naphthalene, rhamnolipid, and water-were carried out at various rhamnolipid concentrations from 0.06 to 100 g/L. Based on the results of diffusometry, the distribution of naphthalene molecules between the states free in solution and states bound by micelles was found. With an increase in the concentration of rhamnolipids, the proportion of bound naphthalene molecules increases from 50% at CRL = 2g/L to 100% at CRL ≥ 50 g/L. The micelle-water partition coefficient Km and the molar solubilization ratio MSR were calculated.

Preparation of PPA based composite reinforcing with glass beads and clays: Investigation of sound absorbing

The research investigates the sound absorption properties of potassium polyacrylate (PPA) composites, particularly those augmented with clay and porous hollow glass beads within a hydrogel template. This unique material combination shows promise for efficient sound absorption, relevant in industries requiring effective noise control like acoustic engineering and construction. Experimental assessment focused on measuring the sound absorption coefficient, crucial for quantifying a material’s ability to absorb sound energy across various frequencies. Incorporating clay and porous hollow glass beads introduces complexities, emphasizing the need for precise acoustic performance prediction. Collected data from sound absorption coefficient measurements formed the basis for training an Artificial Neural Network (ANN) model. Leveraging the ANN’s pattern recognition capabilities, the model learned from diverse composite compositions, enabling accurate prediction of sound absorption coefficients for varying material compositions. This predictive model streamlines material design, offering a systematic approach to tailor composite acoustic characteristics. Integration of machine learning, particularly ANNs, enhances accuracy and expedites material design and optimization, contributing to innovative and customizable sound-absorbing materials for diverse industrial applications.