Half Height Research Articles

Integrated interferometers as a new platform for low cost gas chromatography detection

Gas chromatography is a reference method for gas analysis. As part of efforts to miniaturize gas chromatography systems, the miniaturization of detectors is essential. In this work, we report a new integrated photonic platform for gas chromatography analyte detection. The fabricated silicon die integrates Mach-Zehnder interferometers into low dead volume microfluidic channels, with coherent cost-effective detection scheme with a fixed 850 nm wavelength laser. A proof of concept is demonstrated with the separation and detection of three volatile organic compounds: heptane, octane, and toluene. Peaks’ widths at half height range from 1 to 5 s. Peaks are very well resolved by our system, which acquires more than 100 points per second. From a heptane dilution range, we evaluate the limit of detection of our system to be the headspace of a 0.26 % heptane concentration solution. To our knowledge, these are the first integrated Mach-Zehnder interferometers reported for gas chromatography detection. This work could open new strategies for fast low cost and low limit of detection specific gas chromatography silicon micro-detectors.

Mass calibration of Rosetta’s ROSINA/DFMS mass spectrometer

The Double Focusing Mass Spectrometer (DFMS) onboard the Rosetta spacecraft employs an electrostatic and a magnet sector for energy and mass discrimination, resulting in a high mass resolution. A built-in feedback loop uses the measured magnet temperature to compensate for the temperature dependence of the magnet’s field strength. Still, large onboard temperature variations and other effects cause any given mass peak to move over a range of 30 pixels or more on the detector during the mission. The present paper discusses the various factors that contribute to the time variations in the mass calibration relation. A technique is developed to evaluate and correct for these factors. A mass calibration relation that is valid for the DFMS neutral high mass resolution mode measurements throughout the entire mission for the mass range m/z=13–69 is established and its accuracy is evaluated. The 1σ precision turns out to be less than a single pixel, which is excellent as full peak width at half height is about 12 pixels. The proposed approach provides an a posteriori mass calibration and is useful for all magnet-based mass spectrometers where experimental mass calibration by comparison to reference species, temperature stabilization, and/or electrostatic compensation, are not possible or fail to deliver a mass scale precision that is comparable to the mass resolution of the instrument.

Single-step self-compression of ultrashort pulses below 20 fs by all-fiber supercontinuum generation

We present an ultrashort-pulsed laser source with time-widths as short as 20 fs at around 1.5 µm. For this purpose, the pulses have been spectrally broadened and temporarily compressed by means of supercontinuum generation in a highly nonlinear optical fiber. Inspired by numerical simulations, we have experimentally confirmed that the emission of a resonant dispersive wave is a key indicator for the optimum configuration to achieve maximum temporal compression. No dispersion control stage is needed, which results in the simplicity of the system. An extensive analysis has been made concerning the quality of the pulses obtained, particularly in terms of time-width (at half height and at 1/e height of the maximum) as well as their time-bandwidth product. The complex retrieval of the pulses shows that the smallest temporal width obtained experimentally is 17 fs. A comparison with values found in the literature also shows that our pulses are among the best that can be found with this technology.

Effect of variation in heights of cylindrical pinfins on the thermo-hydraulic performance of an open-microchannel heat sink

This article investigates the impact of different heights of cylindrical micropillars on the thermo-fluid properties of an open microchannel heat sink. The dimensions of the microchannel considered in this study are 0.1 mm × 0.2 mm × 10 mm. Computational fluid dynamics has been employed to simulate seven distinct microchannel layouts. These configurations are Case 1 (Closedmicrochannel with full height pinfins), Case 2 (Openmicrochannel with reduced height pinfins), Case 3 (Openmicrochannel with half height pinfins), Case 4 (Open microchannel with reduced height pinfins at upstream and half height pinfins at downstream), Case 5 (Open microchannel with reduced height pinfins at upstream and half height pinfins at downstream). Case 6 (Open microchannel with two half-height pinfins at upstream and downstream regions, respectively). Case 7 (Open microchannel with two reduced height pinfins at upstream and downstream regions, respectively). Nusselt number, pressure drop, and overall thermal performance of all the considered open configurations of microchannels are evaluated and compared with the plain and closed microchannel for the range of Reynolds number between 150 and 350 by considering water as a working fluid. The results depict that the maximum augmentation in the Nusselt number is about 16.8% achieved by the open microchannel heatsink (Case 2) corresponding to the closed microchannel (Case 1) with a reduction in pressure drop of about 7.32%. To evaluate the mutual effect of heat transfer and pressure drop, overall thermal performance is evaluated. At a lower Reynolds number, the highest performance is associated with Case 2 but at the elevated range of Reynolds number, the maximum performance is acquired by Case 4.

Radiation dose assessment of 7Be and activated corrosion products present in the hydrogen trap of IFMIF-DONES lithium system

The radiological impact that 7Be and activated corrosion products (ACP) dissolved in Li could have in normal operation and maintenance in the surroundings of the hydrogen trap (HT) of future IFMIF-DONES facility has been assessed. Ambient dose equivalent rates were calculated with radiation transport program MCNP at half height of trap. Four different Y contents were considered in the trap: 1, 3, 5 and 8 kg. In normal operation dose rates in the range 13.7–15.1 mSv/h have been found in contact with the trap and 0.28–0.31 mSv/h at 1 m of the trap. 7Be has a very low contribution to dose (3–3.7 µSv/h). Dose simulations have shown that a concrete wall 30 cm thick can reduce dose rates to acceptable dose limits. In maintenance operation the trap is drained and Li film remains attached to Y pebbles. Three possible Li film thickness have been considered: 10, 50 and 100 µm. Estimated 7Be activity is below exemption limits during maintenance. Assessed dose rates are in the range 34–1420 µSv/h at contact with the trap and a maximum of 10.9 µSv/h at 1 m of the trap.

Tunable broadband luminescence of Bi‐ion‐doped glasses via Gd2O3 co‐doping

AbstractThe doping of bismuth (Bi) ions in borosilicate glasses has gained attention for its potential applications in LED light sources and imaging displays. Here, gadolinium oxide (Gd2O3) was introduced into the glass matrix in varying concentrations using a high‐temperature melting method to investigate its impact on the luminescence properties of Bi ions. The resulting glass exhibited bimodal emission peaks at 465 and 750 nm when excited with 325 nm light. The luminescence intensity and fluorescence half width at half height initially increased, followed by a subsequent decrease as the Gd2O3 content in the glass increased from 10 to 43 mol%. Additionally, the color of the luminescence transformed from purple–red to green under white light irradiation. The composition and excitation wavelength of the glass can be adjusted to achieve selective tuning of the luminescence.

Lower-extremity kinematics and kinetics differ based on drop vertical jump variation: An assessment of methodology for a return-to-play protocol using motion analysis

BackgroundThe drop vertical jump (DVJ) is commonly used in return-to-play evaluations to assess movement quality and risk during a dynamic task. However, across biomechanics literature, a multitude of DVJ variations have been used, influencing the generalizability and potential interpretation of the reported findings. Research questionThe purpose of this study was to identify differences in lower extremity kinematics and kinetics between DVJ variations that differ based on horizontal jump distance, verbal instructions, and the use of a jump target. MethodsA single-group repeated measures design was used in a laboratory setting. Twenty participants were tested, and three-dimensional angles and moments of the pelvis, hip, knee, and ankle were computed. Wilcoxon signed rank tests were performed to determine differences between DVJ variations. ResultsReduced knee flexion at initial contact and greater knee extensor moments across the descent phase were observed with increased horizontal jump distance. Additionally, both verbal instructions and a jump target influenced movement strategies at the pelvis, hip, and knee. Ground reaction forces were found to be similar across conditions and jump height following the first landing increased with a target. SignificanceAlthough subtle, the biomechanical differences observed between task variations emphasize the importance of standardizing motion analysis protocols for research and clinical decision-making. Given the findings of the current study, the authors recommend using the Half Height variation in patients treated for a knee injury as it will likely be the most indicative of movement quality.

Generation of ultra-long optical needles with dual-ring cosine filter

Combining the advantages of phase and amplitude modulation, we designed a dual-ring cosine filter which was consisted by an inner and outer ring, and the two rings have different number of paired cosine phase. Using the dual-ring cosine filter, ultra-long longitudinally polarized optical needles were obtained by tight focusing radially polarized Bessel-Gaussian beams with a single lens system. The obtained optical needles have a depth of focus of 268λ, lateral full width of 0.37λ at half height, the beam quality of 94%, and axial uniformity of 95%. In addition, we found that the depth of focus of obtained optical needles can be further stretched and the lateral dimension can be further compressed by increasing the number of paired cosine phase. The ultra-long optical needles were appropriately applied in the fields of optical beam lithography, laser direct writing, particle acceleration, and optical trapping.

Performance Comparison of 7-level Multi-Level Inverter Topologies using FPGA

This paper compares the Multi-Level Inverter namely Switched Ladder and H-Bridge Topologies for the performance parameters. The topologies considered are fed with the switch patterns from the non-carrier angle manipulated formula. The switching angle algorithm identifies on which particular angle the signal has to be generated. It is identified based on four algorithm namely half height method, equal phase method,This paper concentrates on the 7-level MLI AC output using the synthesizable VHDL code and implemented using the FPGA in real-time. For verification in simulation, the cross-compiling is attained using the System Generator tool.

Microstructural and mechanical characterization of pearlitic steel after high intensity laser peening and shot peening

This study investigated the microstructural/mechanical properties of annealed 4340 pearlitic steel after shot peening (SP) and high intensity laser peening (LP). SP at 0.012–0.016 A resulted in fragmentation of the pearlite colonies ∼1–2 µm from the treated surface and sub-surface cracking as well as significant distortion of pearlite colonies ∼30 µm from the treated surface. LP at a pulse energy of 19 J with a pulse full-width half height of 27 ns and a square spot size of 3x3 mm2 resulted in an intense irradiance on the metal surface of 8 GW/cm2. During this process a thin, micrometer-range layer of surface material is ablated which generates and heats a plasma plume in less than 1 ns to a temperature in the range of 15,000 K. A recast layer ∼5–10 µm in thickness from the treated surface with significant porosity was observed in the LPed specimen. The highest average microhardness (266 ± 9 HV) was observed in the SPed specimen ∼63 µm from the treated surface, however the hardness quickly returned to the baseline hardness (218 HV) ∼250–500 µm from the treated surface. In the LPed specimen, the averaged microhardness values exceeded the baseline hardness up to a depth of ∼1500–2000 µm with an average microhardness of 237 ± 4 HV from ∼60–2500 µm from the treated surface. It is shown that LP not only improves the sub-surface microhardness of the 4340 pearlitic steel up to greater depths than SP, but that it also preserves the pearlitic microstructure near the treated surface.

Different aspects of polymer films based on low‐density polyethylene using graphene as filler

AbstractThe focus of the present work is to prepare low‐density polyethylene (LDPE)‐graphene (G) nanocomposite films with improved gas barrier properties by melt extrusion. A narrow range of the graphene (0.05–0.3 wt.%) as filler was used in the LDPE matrix. The rheological analysis indicating that there is no significant influence on the LDPE chains mobility with the addition of filler. The nanocomposites percent crystallinity (Xc%) increase from 25.0% to 31.6% compared to neat LDPE. The X‐ray diffractogram shows a change in width half height of the peak positioned at 26° ((002) plane) from 0.69 (graphite) to 1.24 (graphene), revealing the asymmetry of this plane. The optical microscopy images show a good dispersion of the nanoparticles in the polymer matrix. The mechanical properties of the nanocomposites in longitudinal direction demonstrate better improvement with addition of the filler as compared to the transverse direction. The contact angle measurements of nanocomposites for water and ethylene glycol do not shows a significant variation in comparison to neat LDPE. The nanocomposites show 26% enhancement in the oxygen barrier property. Thus, here we present the cost‐effective LDPE‐graphene nanocomposites with improve oxygen barrier property, which can be used in different industrial application especially in food packaging.

Isomeric separation of native N-glycans using nano zwitterionic- hydrophilic interaction liquid chromatography column

Changes in the expression of glycan isomers have been implicated in the development and progression of several diseases. However, the analysis of structurally diverse isomeric N-glycans by LC−MS/MS is still a major analytical challenge, particularly due to their large number of possible isomeric conformations. Common approaches derivatized the N-glycans to increase their hydrophobicity and to gain better detection in the MS system. Unfortunately, glycan derivatization is time-consuming and, in many cases, adds complexity because of the multiple reaction and cleaning steps, incomplete chemical labeling, possible degradation, and unwanted side reactions. Thus, analysis of native glycans, especially for samples with low abundance by LC−MS/MS, is desirable. Normal phase chromatography, which employs HILIC stationary phase, has been commonly employed for the identification and separation of labeled glycans. In this study, we focused on achieving efficient isomeric separation of native N-glycans using a nano ZIC-HILIC column commonly employed to separate labeled glycans and glycopeptides. Underivatized sialylated and oligomannose N-glycans derived from bovine fetuin and Ribonuclease B were initially utilized to optimize chromatographic conditions, including column temperature, pH of mobile phases, and gradient elution time. The optimized condition was then applied for the isomeric separation of native N-glycans derived from alpha-1 acid glycoprotein, as well as from biological samples. Finally, we confirmed the stability and reproducibility of the ZIC-HILIC column by performing run-to-run comparisons of the full width at half height (FWHM) and retention time on different N-glycans. The variability in FWHM was less than 0.5 min, while that of retention time was less than 1.0 min with %RSD less than 1.0%.

Polydiacetylene-coated gold nanoparticles as a novel plasmonic thermosensor based on the phase transition of the outer shell

We report the synthesis of a core–shell nanostructure formed by a gold nanosphere surrounded by an external layer of poly(10,12-pentacosadiynoic acid). The gold core provides intense SERS signaling, whereas the polymer shell ensures structure stability. We introduce the concept of temperature response induced by phase-transition, as opposed to current plasmonic thermosensors based on surface adsorption of low molecular weight reporters. The behavior of the core–shell nanostructure has been investigated by Variable Temperature SERS (VT-SERS) measurements in the range of 150 – 400 K. The polymer shell is initially in the blue form and converts into the stable red one starting from 290 K. This transition produces temperature effects on the position and the Full Width at Half Height (FWHH) of the ν(–C = C–) peak that are suitable for temperature monitoring. VT-SERS measurements are proved to be useful for studying the behavior of ultrathin polymer films.

Understanding the role of temperature in structural changes of choline chloride/glycols deep eutectic solvents

Deep eutectic solvents (DESs) represent a new “green” alternative to classic organic solvents; however, their high viscosity often limits their utilization. The physicochemical properties of DESs can be tuned by adding cosolvents, by varying the operating temperature, or both, but their structure has to be preserved. In this work, three pure DESs based on choline chloride (ChCl) mixed with diethylene glycol (DEG), triethylene glycol (TEG) or polyethylene glycol 200 (PEG 200), as well as ChCl/TEG/water mixtures were studied. Particular attention was paid to the effect of temperature on some properties, i.e. density, conductivity, and viscosity, and on the structural characteristics of pure DESs and DES/water blends in the range 303–353 K. All the pure eutectic solvents followed both Arrhenius law and Walden's rule and showed very similar activation energy and poor ionicity, indicating the formation of intimate ion pairs. Multinuclear NMR analysis, such as the determination of the chemical shift of 1H, 13C, 35Cl and linewidths at half height of 14N and 35Cl, as a function of temperature highlighted the conservation of the characteristic supramolecular interactions up to 353 K. However, the temperature effects on the physicochemical properties of DES/water mixtures changed differently depending on the water content. Excess properties and NMR investigations highlighted the strengthening of the hydrogen bond interactions up to a 10% level of added water and their progressive weakening at a higher degree of hydration. These results also showed that temperature only slightly affects the structure of both DES and DES/water systems but can drastically increase their transport properties.

Residual stress distributions around indentations and crack in 3Y-TZP ceramics measured using piezo spectroscopy

The residual stress state around indentation and crack in 3Y-TZP ceramics is studied by piezo spectroscopy. The use priority of A1 (≈468 cm−1) peak position is determined by comparing the offset of A1 peak position and A2 (≈648 cm−1) peak position under low pressure and high pressure. The plastic deformation zone is successfully peeled off through the widening of half height width under stress, and the residual stress in the elastic deformation zone around the indentation and crack is predicted more accurately using the Yoffe model. The results show that there is no T-M transformation in the low-pressure zone, so the residual stress distribution is consistent with the Yoffe model results. The residual stress around the crack in the high-pressure zone is completely contrary to the prediction of Yoffe model, because the stress induced phase transformation mechanism causes the residual compressive stress of the highest 8 GPa and 80 vol% of the phase variable at the crack tip.

Equivalent carbon number-based targeted odd-chain fatty acyl lipidomics reveals triacylglycerol profiling in clinical colon cancer

Odd-chain FAs (OCFAs) are present in very low level at nearly 1% of total FAs in human plasma, and thus, their functions were usually ignored. Recent epidemiological studies have shown that OCFAs are inversely associated with a variety of disease risks. However, the contribution of OCFAs incorporated into complex lipids remains elusive. Here, we developed a targeted odd-chain fatty acyl-containing lipidomics method based on equivalent carbon number and retention time prediction. The method displayed good reproducibility and robustness as shown by peak width at half height within 0.7 min and coefficient of variation under 20%. A total number of 776 lipid species with odd-chain fatty acyl residues could be detected in the ESI mode of reverse-phase LC-MS, of which 309 lipids were further validated using multiple reaction monitoring transitions. Using this method, we quantified odd-chain fatty acyl-containing lipidome in tissues from 12 colon cancer patients, revealing the remodeling of triacylglycerol. The dynamics of odd-chain fatty acyl lipids were further consolidated by the association with genomic and proteomic features of altered catabolism of branched-chain amino acids and triacylglycerol endogenous synthesis in colon cancer. This lipidomics approach will be applicable for screening of dysregulated odd-chain fatty acyl lipids, which enriches and improves the methods for diagnosis and prognosis evaluation of cancer using lipidomics.

A Single DC Source Five-Level Switched Capacitor Inverter for Grid-Integrated Solar Photovoltaic System: Modeling and Performance Investigation

Boost converters and multilevel inverters (MLI) are frequently included in low-voltage solar photovoltaic (PV) systems for grid integration. However, the use of an inductor-based boost converter makes the system bulky and increases control complexity. Therefore, the switched-capacitor-based MLI emerges as an efficient DC/AC voltage convertor with boosting capability. To make classical topologies more efficient and cost-effective for sustainable power generation, newer topologies and control techniques are continually evolving. This paper proposes a reduced-component-count five-level inverter design for generating stable AC voltages for sustainable grid-integrated solar photovoltaic applications. The proposed topology uses seven switching devices of lower total standing voltage (TSV), three diodes, and two DC-link capacitors to generate five-level outputs. By charging and discharging cycles, the DC capacitor voltages are automatically balanced. Thus, no additional sensors or control circuitry is required. It has inherent voltage-boosting capability without any input boost converter. A low-frequency-based half-height (HH) modulation technique is employed in the standalone system for better voltage quality. Extensive simulations are performed in a MATLAB/Simulink environment to estimate the performance of the proposed topology, and 17.58% THDs are obtained in the phase voltages. Using a small inductor in series or an inductive load, the current THD reduces to 8.23%. Better dynamic performance is also observed with different loading conditions. A miniature five-level single-phase laboratory prototype is developed to verify the accuracy of the simulation results and the viability of the proposed topology.

Modeling of temperature profile in semi-permeable membrane channel at non-isothermal conditions

We present a model for thermo- and pressure-driven membrane processes accompanied by transmembrane water and heat fluxes combined in a single unit. High-pressure channel (high-pressure control volume) is characterized by low operating temperature and vice versa. A symmetric plate-and-frame membrane channel was considered in this study. An elementary parallelepiped was selected as a control volume. Balance equations were written over the control volume. A membrane element was represented as a set of conjugate semipermeable volumes. The model is based on the following assumptions: (1) incompressible fluid under steady-state conditions; (2) trans-membrane water flux is opposed to transmembrane heat flux. Transverse velocity profile is approximated by Berman distribution; (3) the mechanisms of transverse transport include: convection resulting from pressure differences and conduction resulting from temperature gradients; (4) the thickness of thermal layer is equal to half height of the channel (δt=H). The temperature polarization (TP) module reveals high sensitivity to thermo-physical properties and hydrodynamics such as to the coefficient of thermal diffusivity a=λ/cρ and to the transverse velocity, V(z). We find that (a) variation of the coefficient of thermal diffusivity in liquid phase from a= 2.0 10−7 m2/s to a= 1.0 10−7 m2/s will reduce TP module from 0.96 to 0.91; (b) variation of transverse velocity at the membrane surface from 5.5 10−5 to 1.5 10−5 m/s can decrease of TP module from 0.95 to 0.79. The developed solution can be used as a sub-model for quantitative estimation of TP phenomena in thermo-driven membrane operations. It can be applied for analysis of pressure-driven processes at non-isothermal conditions and be used as a mathematical algorithm for process analysis and optimization.

Design and simulation of an asymmetrical 23-level inverter with modulation Techniques

For medium voltage, high power regulation the Multilevel Inverters (MLI) are attracting industry and academic researchers. MLI generates the desired output in the form of stepped waveforms with reduced harmonics. The MLI is expected to be realised using a variety of traditional topologies. Traditional MLIs have the disadvantage of requiring additional components, which increases the complexity of gate pulse production. As a result, MLI's overall costs will rise. This research proposes a hybrid topology to alleviate these drawbacks. With the increase in the number of steps in output voltage, the number of dc sources, power switching devices, converter cost, and space required is significantly reduced compared to typical MLIs. The design and simulation of a hybrid converter using several types of PWM approaches are covered in this work. This hybrid converter combines a T-Type structure and a half bridge inverter that is back-to-back connected. The proposed construction is designed and simulated by MATLAB Simulink software. The proposed 23 level inverter circuit is designed and simulated by Equal phase angle modulation technique and half height modulation technique, THD is compared.

Внеосевой асферический коллектор для экстремальной ультрафиолетовой литографии и мягкой рентгеновской микроскопии

By the method of ion-beam shape correction, a small-sized ion beam formed a non–axisymmetric aspherical profile of the collector surface for an extreme ultraviolet radiation source TEUS-S100 with a numerical aperture of NA= 0.25, PV on the surface is 36.3 microns, the surface shape accuracy by standard deviation is 0.074 microns, which allowed to obtain a focusing spot with a width of 300 microns at half-height. To solve the problem, the technological ion source KLAN-53M was upgraded – the flat ion-optical system was replaced with a focusing one. The ion-optical system consisting of a pair of concave grids with a radius of curvature of 60 mm provided the following parameters of the ion beam: the ion current is 20 mA, the width at half–height is 8.2 mm at a distance of 66 mm from the cutoff of the ion source.