Scan Mode Research Articles

Raman spectroscopy for the identification of body fluid traces: Semen and vaginal fluid mixture

Raman spectroscopy is a versatile research tool that has found numerous practical applications recently. High specificity, non-destructive nature, and potential for on-field application make Raman spectroscopy an attractive tool for forensic science. The great potential of Raman spectroscopy for confirmatory identification of all main body fluids has been recently reported (Vyas et al. Forensic Chemistry 2020, 100247). Bringing the developed methodology from the laboratory to the crime scene requires further method development and validation for realistic, practical samples subjected to environmental conditions, contamination, substrate interference, aging, etc. This work targets the validation of the developed methodology for body fluid mixtures, semen, and vaginal fluid in particular, which are critical for sexual assault cases. Near-infrared (NIR) Raman spectra of dry semen-vaginal fluid mixtures were acquired in automatic scanning mode and subjected to advanced statistical analysis. Support Vector Machine Discriminant Analysis (SVMDA) was used to develop three binary classification models, including vaginal fluid vs mixture, semen vs mixture, and semen vs vaginal fluid. These binary models were combined to build a single tertiary model, which resulted in the 100% correct classification on the sample level for all examined mixtures (1.5% to 100% for vaginal fluid and 3% to 100% for semen). The developed analytical approach could be used for various other applications when complex binary mixtures need to be detected and analyzed.

Laser Additive Manufacturing of 316L Stainless Steel Thin-wall Ring Parts

The process parameters of laser additive manufacturing have an important influence on the forming quality of the produced items or parts. In the present work, a finite element model for simulating transient heat transfer in such processes has been implemented using the ANSYS software, and the temperature and stress distributions related to 316L stainless steel thin-walled ring parts have been simulated and analyzed. The effect of the laser power, scanning speed, and scanning mode on temperature distribution, molten pool structure, deformation, and stress field has been studied. The simulation results show that the peak temperature, weld pool size, deformation, and residual stress increase with an increase in laser power and a decrease in the scanning speed. The scanning mode has no obvious effect on temperature distribution, deformation, and residual stress. In addition, a forming experiment was carried out. The experimental results show that the samples prepared by laser power P = 800 W, V = 6 mm/s, and the normal scanning method display good quality, whereas the samples prepared under other parameters have obvious defects. The experimental findings are consistent with the simulation results.

Quantitative GC-MS Analysis of Sawdust Bio-Oil

Bio-oils from biomass pyrolysis have a highly promising potential as biofuels or sources of chemicals. The quantitative analysis of bio-oils is quite difficult and requires many standards. In this study, we developed a methodology using only 16 standards for determining the concentration of 49 compounds, representatives of the main chemical classes commons in bio-oils, using relative response factors (RRF) and analytical curves. Five Pinus sawdust bio-oils were analyzed using a GC-MS-DB-5 capillary column (60 m). SCAN mode (from 45 to 450 Daltons) and retention indices (LPTRI) were used for qualitative analysis. For quantitative analysis, SIM mode was preferred, and analytical curves were constructed from an initial solution at 400 mg g-1 of each of the 16 standards, with concentrations ranging from 1 to 150 mg g-1 added to the internal standard (methyl hexanoate) at 70 mg g-1. After the positive identification and quantification of 9 compounds (among the 16 standards used), the other compounds were quantified using the RRF obtained from a standard solution at 30 mg g-1, considering the similarities with those identified standards. 196 compounds were identified, while 49 compounds were quantified, highlighting the monoaromatic hydrocarbons, naphthalenes, benzofurans, alkyl phenols, and catechols.

BEAM-PLASMA REACTORS FOR FUNCTIONAL GRADIENT MATERIALS PRODUCTION

Application and perspectives of beam-plasma chemical rectors generating cold hybrid plasma for production of functionally graded polymeric materials for tissue engineering and regenerative medicine are considered. Oxygen hybrid plasma was produced by joint action of a continuous or intermittent electron beam and a capacity coupled radio-frequency (RF) gas discharge (13.56 MHz) on gaseous media at moderate pressures (~ 1000 Pa). The scanning electron beam (accelerating voltage, 30 kV, and beam current, 1-1.5 mA) was injected through the grid of the active RF electrode; polymeric samples were placed in the gap between electrodes of the RF-discharge system. Electron beam characteristics, namely, scanning mode and power, can instantly and independently control the reaction volume geometry as well as concentrations of active plasma particles. Methods for such control by means of the scanning of intermittent electron beams are described. As a result, the RF discharge can be accurately localized on the desirable zone of the polymeric surface forming abruptly structured patterns or smooth gradients of functionalities, while radiation and thermal damages of polymers are prevented. The approach was tested using polymethylmethacrylate, polyethylenterphtalate, and polycarbonate samples, and the changes in the chemical composition and hydrophilic properties of their surfaces were shown, which are associated with the improvement of biocompatibility of the plasma-modified polymers.

Determination of five amanita peptide toxins in poisonous mushrooms by ultra performance liquid chromatography-quadrupole electrostatic field orbitrap high resolution mass spectrometry

Food poisoning by toxic mushrooms occurs frequently worldwide. It is one of the most common food poisoning events and the main cause of death. Amanita peptide toxins are the most common lethal toxins in poisonous mushrooms. Presently, a novel method based on ultra performance liquid chromatography-quadrupole electrostatic field orbitrap high resolution mass spectrometry (UPLC-Q/Orbitrap HRMS) was developed for the determination of five amanitapeptide toxins (α-amanitin, β-amanitin, γ-amanitin, phalloidin, and phallacidin). Because the isotope summit of α-amanitin affects the detection of β-amanitin, it cannot be distinguished by low resolution mass spectrometry. Therefore, experimental conditions including chromatography and mass spectrometry were explored in detail. The five peptide toxins were extracted from poisonous mushrooms with pure water and filtered through a 0.22 μm teflon microporous membrane. The procedure was rapid, simple, and environmentally friendly. Chromatographic separation was performed on a strong polarity HSS T3 column (100 mm×2.0 mm, 2.1 μm) with gradient elution using acetonitrile and 5 mmol/L ammonium acetate containing 0.1% (v/v) formic acid as mobile phases at a flow rate of 0.3 mL/min. The column temperature was set to 40 ℃. The analytes were ionized using a heating electrospray ionization source and collected in positive ion mode. Full scanning/data-dependent secondary mass spectrometry (Full mass-ddMS2) mode was used for qualitative analysis of the targets within 10 min. The target ion selective scan (Targeted-SIM) mode was used for quantification by external standard calibration. The measured and theoretical values of the exact mass and the MS2 fragment ions of the five compounds were within an error of 5×10-6. Method validation was performed according to the criteria recommended by the Chinese National Standard. All the compounds showed an excellent linear relationship in the range of 1.0-20.0 μg/L. The correlation coefficients (r) ranged from 0.9974 to 0.9989. The limit of detection was 0.006 mg/kg for all five compounds. Recoveries ranged from 81.8% to 102.4%. There was no matrix effect in the blank mushroom sample for the five compounds, and the relative standard deviations ranged from 3.2% to 8.3%. This method provides abundant compound characteristic mass information, such as retention time, exact mass, fragment ions, and other information. The data can be used to identify suspected compounds based on the extracted ion flow diagram and isotope distribution information. Comparison between the actual exact mass and the theoretical exact mass, combined with the fragment ions enables identification of the structures of unknown compounds and collision methods, which can be confirmed in the absence of standard materials. In this study, the isomer of γ-amanitin was identified as amaninamide. The novel method is simple, accurate, specific, and sensitive. The method permits the rapid qualitative and quantitative detection of compound in public health emergency settings and will provide reliable technical support for the rapid screening of such toxic compounds and the structural locking of unknown toxins in the future.

Simultaneous Determination of nicotinamide, kojic acid, Tranexamic acid, raspberry glycoside, azelaic acid, magnesium ascorbate phosphate and β-Arbutin in whitening cosmetics by UPLC-MS/MS

A UPLC-MS/MS method was developed for simultaneous determination of 7 whitening ingredients: nicotinamide, kojic acid, Tranexamic acid, raspberry glycoside, azelaic acid, magnesium ascorbate phosphate and β-Arbutin in cosmetics. The whitening active components were extracted from cosmetics by supersonic extraction with sodium chloride and dichloromethane to disperse the sample, and supersonic extraction with 0.015 mol/L potassium dihydrogen phosphate solution purified by HLB solid phase extraction column, scanned and detected by electrospray ionization source with positive and negative ion alternate scanning mode and multiple reaction monitoring mode. The results showed that the whitening active ingredients were separated within 3 minutes, with a good linear relationship (R>0.999), and the detection limit was 0.10mg/kg~0.75mg/kg. The recoveries (n=6) were 78.84%-104.85%, and the RSDs were 0.24%-11.35%. This method is suitable for the rapid determination of whitening active ingredients in cosmetics.

Quantification of 37 glucocorticoids in chicken muscle by UHPLC-Q-Orbitrap-MS with parallel reaction monitoring.

The quantification capability of high-resolution mass spectrometry (HRMS) has received increasing interest from analysts. In this study, we present a method for analyzing 37 glucocorticoids in chicken muscle using UHPLC-Q-Orbitrap MS with parallel reaction monitoring (PRM). The analytes were extracted using acetonitrile (ACN) containing 0.1% formic acid and subjected to commercial PRiME HLB solid-phase extraction (SPE) cartridge clean-up. Under optimized conditions, the analytes were separated on an analytical column and subsequently detected using a high-resolution hybrid quadrupole/Orbitrap mass spectrometer coupled with PRM scan mode. The Q-Orbitrap with PRM exhibited remarkable sensitivity, with limits of quantification (LOQs) ranging from 0.08 μg kg-1 to 7.59 μg kg-1. To validate the method, we conducted intra- and inter-day tests using a blank matrix sample at different spiking levels. The achieved results demonstrated satisfactory recovery values (74.1-97.5%) and precise results (RSDs < 15%) for all the studied analytes. In application, we found dexamethasone with 6.5 μg kg-1 and fluorometholone with 3.9 μg kg-1 in two chicken samples. These findings suggest that the UHPLC-Q-Orbitrap system, in conjunction with the SPE sample preparation method, has great potential as a routine quantification approach for multiple glucocorticoid residues in chicken samples.

SAR Imaging in Frequency Scan Mode: System Optimization and Potentials for Data Volume Reduction

Frequency scanning (FScan) is an innovative acquisition mode for synthetic aperture radar (SAR) systems. The method is based on the frequency-dependent beam pointing capabilities of phased array antennas, artificially increased via the combined use of true time delays and phase shifters within the array antenna. By this, typical limitations of conventional SAR systems in terms of achievable swath width and azimuth resolution can be mitigated, and so a wide swath can be imaged maintaining a fine azimuthal resolution. In the first part of the article, we introduce the theoretical concept, which is necessary to evaluate the reduced echo window length (EWL) with respect to equivalent stripmap data and the implications for the transmit pulse characterization. An FScan sensor flying in a TerraSAR-X-like orbit is shown to be capable of imaging an 80-km wide swath with 1-m azimuth resolution. The resulting time–frequency properties of the recorded raw data make the traditional SAR data compression algorithms such as block-adaptive quantization (BAQ) highly inefficient in this case. Therefore, the second part of the article investigates dedicated quantization methods for efficient data volume reduction in FScan systems. Different solutions are investigated and evaluated through simulations. Various transformations of the raw data have been exploited to optimize the encoding process, including deramping, fast Fourier transform (FFT), and blockwise approaches. Compared with standard BAQ in the time domain, the suggested data compression methods significantly improve the resulting signal-to-quantization noise ratio, allowing for the reduction in the overall data volume by about 60% for the considered system scenario, while maintaining robustness in the presence of inhomogeneous scene characteristics at the cost of a modest complexity increase for its on-board implementation.

Improving CT Quality for Complex Objects With the Novel Autoexposure Imaging of Stepped Voltage Scanning

For X-ray CT imaging of complex objects, the tube voltage is an important parameter. At fixed voltage, the complete projection cannot be obtained because the voltage does not match the equivalent attenuation thickness of the object at different CT scanning angles under the limitation of the dynamic range of the imaging system. Multivoltage exposure imaging is an effective solution. However, due to the limitation of high-voltage-regulation ripple, the imaging efficiency is very low if the voltage is adjusted frequently. Actually, for a ray detector with a wide dynamic range, the small difference in equivalent thickness between adjacent scanning angles cannot affect the imaging quality for complex objects. Therefore, this article proposes a novel autoexposure imaging method with stepped voltage scanning. First, according to the known imaging system, the voltage regulation method of stepped voltage adjustment is researched by evaluating the image quality of different thicknesses. Then, considering that stepped voltage adjustment cannot obtain the complete projection at the thinner thickness, the projections of negative logarithmic transformation (NLT), with stepped voltage and low voltage, are fused to obtain the high dynamic range (HDR) projection. Finally, the method is validated on both a customized titanium specimen and an actual engine blade. The results show that the proposed method can achieve HDR CT imaging of complex objects with higher quality and clearer edge details. Additionally, this new scanning mode of stepped voltage adjustment can reduce the frequency of voltage adjustment and improve imaging efficiency.

Влияние импульсного и сканирующего светодиодного излучения на биохимический состав и продуктивность капусты японской сорта Мизуна Ред

When growing plants in light culture, particularly effective are energy-saving LED irradiators with long service life, low heat dissipation and small size, as well as an ability to be closely located to the plants and possibility of regulating the intensity and spectrum of illumination. To evaluate the effect of irradiation modes on plants and energy expenditure under these regimes, the productivity of plant products of Japanese cabbage variety Mizuna Red and their biochemical composition were studied. Plants were illuminated by specially designed LED lamps produced by VIM with a dynamically adjustable spectral composition in four channels. Experimental studies were conducted under three radiation modes: continuous (control), pulsed and scanning with a total photosynthetic active radiation of 321 μmol/m²s in the proportion of B:G:R:FR ~ 30:26:38:6. Parameters of aboveground mass and dry matter formation were determined twice on the 15th and 30th days of the growing season. It was found that under the pulsed radiation mode the content of dietary fibres in leaves compared to continuous illumination (control) is 64.3% higher, and ash content - 19.1% higher. The increased content of ascorbic acid and choline has also been noted. The application of the pulsed mode of radiation increased the content of carbohydrates in the tissues of Mizuna Red shoots by 71.4% as compared to the scanning mode.

A comprehensive and high-throughput screening method for multiple prohibited substances by UPLC-QE Plus-HRMS and HPLC-QQQ-MS in human urine for doping control.

Since the World Anti-Doping Agency's (WADA) Prohibited List is updated on an annual basis, screening methods must be continually adapted to align with these changes. In accordance with Technical Document-MRPL 2022, a newly combined, comprehensive, rapid and high-throughput doping control screening method has been developed for the analysis of 350 substances with different polarities in human urine using ultra-high performance liquid chromatography coupled with Q Exactive Plus Hybrid Quadrupole-Orbitrap mass spectrometer (UPLC-QE Plus-HRMS) and ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometer (UPLC-QQQ-MS). The limits of detection were in the range of 0.12-50 ng mL-1 for beta-2 agonists, hormone and metabolic modulators, narcotics, cannabinoids and glucocorticoids, 0.1-14 ng mL-1 for the manipulation of blood and blood components, beta blockers, anabolic agents and hypoxia-inducible factor (HIF) activating agents, and 2.5-100 000 ng mL-1 for substances of Appendix A, diuretics & masking agents and stimulants. The sample preparation consisted of two parts: one is the dilute & shoot part analyzed in UPLC-QQQ-MS, another is a mixture of the dilute & shoot part and a liquid-liquid extraction part of hydrolyzed human urine analyzed in UPLC-QE Plus-HRMS in full scan mode with polarity switching and parallel reaction monitoring (PRM) mode. The method has been fully validated for doping control purposes. All the substances were compliant with WADA's required 1/2 minimum requirement performance level (MRPL) or minimum reporting level (MRL), and this method was successfully used in the 2022 Beijing Winter Olympic Games and Winter Paralympic Games for anti-doping purpose.

Применение газовой хромато-масс-спектрометрии для определения содержания хлорорганических соединений в химических реагентах

The possibilities of gas chromatography mass spectrometry for determining of organochlorine compounds content in chemical reagents are shown . The optimal operating conditions of the chromato mass spectrometer and the optimal solvent for extraction- isooctane were selected using the example of organochlorine compounds ( model mixture analysis. Calibration curves were constructed for each individual organochlorine compound at selected ion monitoring (SIM) mode. Different approaches to sample preparation based on dilution and/or extraction are proposed depending on the physico-chemical characteristics of chemical reagents. For the analysis of chemical reagents having a strong hydrocarbon background in the full ion current scanning mode, the identification of organochlorine compounds and subsequent quantitative determination were carried out by using mass fragmentograms. To estimate the efficiency of the technique, the completeness of extraction was assessed by adding a so-called "marker" to the working sample and evaluating the results by the value of the extraction degree.

Identification and characterization of the grinding burns by eddy current method

Abstract This work presents an attempt to identify local changes in materials caused by local grinding burnings by using the eddy current (EC) method. The locally heat-treated AISI 9310 steel specimen was prepared by using a laser surfacing process to imitate three different grinding burns. These burn marks were characterized in terms of changes in microstructure and hardness on the surface and cross-section of the specimen. On such a basis, the depth of the heat-affected zone caused by the grinding tool was examined. Subsequently, the specimen was subjected to the EC measurements for the quantitative description of the signal from each of the defects by using a commercial NORTEC 600D flaw detector working in specimen scanning mode and with a pencil probe. The changes in the amplitude and the phase angle of the signal from three defects indicate the possibility to identify burns along with their quantitative description and subsequent estimation of their depth. The differences in the phase angle value, related to the local changes in the stress state, serve as an effective indicator of the specimen overheating degree in the area of the EC induction.

The Analysis of Correction Effect of Motion Artifacts in PET Images Using Respiratory Gating System

PET is used effectively for biochemical or pathological phenomena, disease diagnosis, prognosis determination after treatment, and treatment planning because it can quantify physiological indicators in the human body by imaging the distribution of various biochemical substances. However, since respiratory motion artifacts may occur due to the movement of the diaphragm due to breathing, we would like to evaluate the practical effect by using the a device-less data-driven gated technique called Motion Free (DDG) with the phase-based gating correction method called Q.static scan mode. In this study, images of changes in moving distance (0 cm, 1 cm, 2 cm, 3 cm) and degree of slope (0°, 2.5°, 5°, 10°) were acquired using a breathing-simulated moving phantom. The diameters of the six spheres in the phantom are 10 mm, 13 mm, 17 mm, 22 mm, 28 mm, and 37 mm, respectively. According to SUVmax and SUVmean measurements, when DDG was applied based on the moving distance, the average SUVmax of the correction effect by the moving distance was improved by 1.92, 2.48, 3.23 and 3.00, respectively, and the average SUVmean was improved by 0.04, 0.72, 1.36 and 1.49, respectively. When DDG was applied based on the diameter of the phantom spheres, the average SUVmax of the correction effect by the moving distance was improved by 2.37, 2.02, 1.44, 1.20, 0.42 and 0.52, and the average SUVmean was improved by 1.36, 1.23, 0.99, 0.82, 0.57 and 0.43, respectively. The correction effect by the degree of slope also improved the average SUVmax when DDG was applied to 2.93, 2.87, 1.61 and 1.45 respectively, and the average SUVmean to 1.61, 1.27, 0.8 and 0.95 respectively, based on the degree of slope. when DDG was applied based on the diameter of the phantom sphere, the average SUVmax was improved by 0.77, 1.73, 1.84, 2.56, 3.46 and 2.93 respectively and the average SUVmean was improved by 0.56, 0.44, 1.19, 0.98, 1.66 and 2.13, respectively. In the visual comparison due to the change of the moving distance and the degree of slope, it was found that the more the moving distance increases, the greater the degree of slope increases, the greater the correction effect of DDG. In the case of the area ratio, Based on the image with a moving distance of 0 cm, when moving distance was 1 cm, 2 cm and 3 cm, the difference between applying and not applying DDG was 5%, 12%, and 18%, respectively. Based on an image with degree of slope of 0°, when degree of slope was 2.5°, 5° and 10°, the difference between applying and not applying DDG was 6%, 7%, and 7%, respectively. In the case of the average density ratio, Based on an image with a moving distance of 0 cm, when moving distance was 1 cm, 2 cm and 3 cm, the difference between applying and not applying DDG was 3%, 6%, and 8%, respectively. Based on an image with degree of slope of 0°, when degree of slope was 2.5°, 5° and 10°, the difference between applying and not applying DDG was 3%, 4%, and 5%, respectively. In the comparison of FWM, FWHM, and FWTM, Based on the image with a moving distance of 0 cm, when moving distance was 1 cm, 2 cm and 3 cm, the difference between applying and not applying DDG was 1.6%, 9% and 9.4% in FWM, 4.4%, 7.6% and 6.4% in FWHM, 12.1%, 23.4% and 30.5% in FWTM respectively. Based on an image with degree of slope of 0°, when degree of slope was 2.5°, 5° and 10°, the difference between applying and not applying DDG was 3.0%, 3.2% and 11.7% in FWM, 2.7%, 5.0% and 2.3% in FWHM, 12.2%, 6.3%, and 7.5% in FWTM respectively. It means there is a quantitative correction effect when applying DDG. This shows that the overall experiment has a correction effect when applying DDG.

Fraction Frequency and Random Scanning Mode for Electron Beam Thermal Assessment

Development of thermal assessment technology is crucial to the security assessment of hypersonic vehicles. A strategy of high-precision reconstructions of nonuniform heat flux and temperature field characteristics of a hypersonic vehicle surface by a scanning electron beam is constructed, and a fraction frequency and random scanning mode that can significantly reduce the temperature fluctuation of materials is proposed. The reconstruction effects in this scanning mode are successively investigated in the HIFiRE-5b flight condition and the reentry condition of the capsule of Apollo 6, showing that the reconstruction accuracies of the heat flux and temperature fields are within 2 and 5%, respectively, and the temperature history is accurately reconstructed with an amplitude of temperature fluctuation below 11 K. This research is expected to promote the electron beam thermal assessment to reconstruct the thermal boundary conditions of hypersonic vehicles more realistically.

Assessment of Micro- and Nanoplastic Composition (Polymers and Additives) in the Gastrointestinal Tracts of Ebro River Fishes

One of the main routes of fish exposure to micro- and nanoplastics (MNPLs) is their ingestion. MNPLs can act as reservoirs of organic contaminants that are adsorbed onto their surfaces, or that can leach from their complex formulations, with potential impacts on biota and along the aquatic food chain. While MNPLs have been reported in fishes worldwide, complete information on MNPL compositions, polymers and additives continues to be scarce. In this work, the presence of MNPLs in the gastrointestinal tracts (GIT) of fish from the Ebro River (Spain) was investigated using a double suspected screening approach to assess and quantify polymers and additives. The sample-preparation procedure consisted of sequential alkaline and acidic digestions with KOH and HNO3, followed by ultrasonic-assisted extraction (USAE) with toluene. The analysis of polymers was carried out with size-exclusion chromatography followed by high-resolution mass spectrometry using an atmospheric pressure photoionization source, operating in negative and positive ionisation modes (SEC-(±)-APPI-HRMS) using full-scan acquisition (FS). Plastic additives were assessed using high-performance liquid chromatography with a C18 analytical column coupled to HRMS equipped with an electrospray ionisation source operating under positive and negative conditions (LC-(±ESI)-HRMS). The acquisition was performed in parallel with full-scan (FS) and data-dependent scan (ddMS2) modes, working under positive and negative ionisation modes. The polymers most frequently detected and quantified in fish GITs were polysiloxanes, polyethylene (PE), polypropylene (PP) and polystyrene (PS). PE was detected in 84% of the samples, with a concentration range from 0.55 to 3545 µg/g. On the other hand, plasticisers such as phthalates and stabilisers such as benzotriazoles were the most frequently identified plastic additives.

Advanced Mapping of Optically-Blind and Optically-Active Nitrogen Chemical Impurities in Natural Diamonds

Natural diamonds with a rich variety of optically blind and optically active nitrogen impurity centers were explored at a nano/microscale on the surface and in bulk by a number of advanced chemical and structural analytical tools in order to achieve a comprehensive characterization by establishing enlightening links between their analysis results. First, novel compositional relationships were established between high-energy X-ray photoelectron spectroscopy (XPS) and low-energy Fourier-transform infrared vibrational spectroscopy (FT-IR) signals of nitrogen impurity defects acquired in the microscopy mode at the same positions of the diamond surface, indicating the verification XPS modality for qualitative and quantitative FT-IR analysis of high concentrations of nitrogen and other chemical impurity defects in diamond. Second, depth-dependent spatial distributions of diverse photoluminescence (PL)-active nitrogen defects were acquired in the confocal scanning mode in an octahedral diamond and then for the first time corrected to the related Raman signals of the carbon lattice to rule out artefacts of the confocal parameter and to reveal different micron-scale ontogenetic layers in the impurity distributions on its surface. Third, intriguing connections between local structural micro-scale defects (dislocation slip bands of plastic deformation zones) visualized by optical microscopy and Raman microspectroscopy, and related distributions of stress-sensitive PL-active nitrogen impurity defects in the proximity of these planes inside bulk diamonds were revealed. These findings demonstrate the broad instrumental opportunities for comprehensive in situ studies of the chemical, structural, and mechanical micro-features in diamonds, from the surface into bulk.

Validating a double Gaussian source model for small proton fields in a commercial Monte-Carlo dose calculation engine

PurposeThe primary fluence of a proton pencil beam exiting the accelerator is enveloped by a region of secondaries, commonly called “spray”. Although small in magnitude, this spray may affect dose distributions in pencil beam scanning mode e.g., in the calculation of the small field output, if not modelled properly in a treatment planning system (TPS). The purpose of this study was to dosimetrically benchmark the Monte Carlo (MC) dose engine of the RayStation TPS (v.10A) in small proton fields and systematically compare single Gaussian (SG) and double Gaussian (DG) modeling of initial proton fluence providing a more accurate representation of the nozzle spray. MethodsThe initial proton fluence distribution for SG/DG beam modeling was deduced from two-dimensional measurements in air with a scintillation screen with electronic readout. The DG model was either based on direct fits of the two Gaussians to the measured profiles, or by an iterative optimization procedure, which uses the measured profiles to mimic in-air scan-field factor (SF) measurements. To validate the DG beam models SFs, i.e. relative doses to a 10 × 10 cm2 field, were measured in water for three different initial proton energies (100MeV, 160MeV, 226.7MeV) and square field sizes from 1×1cm2 to 10×10cm2 using a small field ionization chamber (IBA CC01) and an IBA ProteusPlus system (universal nozzle). Furthermore, the dose to the center of spherical target volumes (diameters: 1cm to 10cm) was determined using the same small volume ionization chamber (IC). A comprehensive uncertainty analysis was performed, including estimates of influence factors typical for small field dosimetry deduced from a simple two-dimensional analytical model of the relative fluence distribution. Measurements were compared to the predictions of the RayStation TPS. ResultsSFs deviated by more than 2% from TPS predictions in all fields <4×4cm2 with a maximum deviation of 5.8% for SG modeling. In contrast, deviations were smaller than 2% for all field-sizes and proton energies when using the directly fitted DG model. The optimized DG model performed similarly except for slightly larger deviations in the 1×1cm2 scan-fields. The uncertainty estimates showed a significant impact of pencil beam size variations (±5%) resulting in up to 5.0% standard uncertainty. The point doses within spherical irradiation volumes deviated from calculations by up to 3.3% for the SG model and 2.0% for the DG model. ConclusionProperly representing nozzle spray in RayStation’s MC-based dose engine using a DG beam model was found to reduce the deviation to measurements in small spherical targets to below 2%. A thorough uncertainty analysis shows a similar magnitude for the combined standard uncertainty of such measurements.

Synchro-PASEF Allows Precursor-Specific Fragment Ion Extraction and Interference Removal in Data-Independent Acquisition

Data-independent acquisition (DIA) methods have become increasingly popular in mass spectrometry–based proteomics because they enable continuous acquisition of fragment spectra for all precursors simultaneously. However, these advantages come with the challenge of correctly reconstructing the precursor–fragment relationships in these highly convoluted spectra for reliable identification and quantification. Here, we introduce a scan mode for the combination of trapped ion mobility spectrometry with parallel accumulation—serial fragmentation (PASEF) that seamlessly and continuously follows the natural shape of the ion cloud in ion mobility and peptide precursor mass dimensions. Termed synchro-PASEF, it increases the detected fragment ion current several-fold at sub-second cycle times. Consecutive quadrupole selection windows move synchronously through the mass and ion mobility range. In this process, the quadrupole slices through the peptide precursors, which separates fragment ion signals of each precursor into adjacent synchro-PASEF scans. This precisely defines precursor–fragment relationships in ion mobility and mass dimensions and effectively deconvolutes the DIA fragment space. Importantly, the partitioned parts of the fragment ion transitions provide a further dimension of specificity via a lock-and-key mechanism. This is also advantageous for quantification, where signals from interfering precursors in the DIA selection window do not affect all partitions of the fragment ion, allowing to retain only the specific parts for quantification. Overall, we establish the defining features of synchro-PASEF and explore its potential for proteomic analyses.

Validation of gas chromatographic methods for lavender essential oil authentication based on volatile organic compounds and stable isotope ratios

A combination of Gas Chromatography-tandem Mass Spectrometry (GC-MS/MS) and Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) methods is a powerful tool to control false declaration of various food matrices including lavender essential oil. However, the methods need to be validated to demonstrate data reliability.In the present study, we developed a GC-MS/MS method for determining volatile organic compounds in lavender essential oil. For this, a single chromatographic run was optimised to separate thirty-eight pure reference standards in<17 min using a suitable capillary column, a faster injection system, temperature ramp gradient, and acquiring mass spectra through dynamic monitoring reaction and full scan mode. The GC-MS/MS method was validated according to the “Harmonised guidelines of IUPAC” considering parameters such as linearity range, limit of detection, limit of quantification, regression coefficient, repeatability and reproducibility. The validation parameters suggested that the method was sufficiently sensitive, precise and accurate for the determination of VOCs.Moreover, we developed a GC-IRMS method to characterize the isotope ratios of carbon (δ13C) and hydrogen (δ2H) of a large selection of the VOCs present in the lavender oil. For this, different matrices of various essential oil compounds of known δ13C and δ2H values (obtained from bulk isotope ratio analysis) were analysed in the GC-IRMS. Similarly to the GC-MS/MS method, the GC-IRMS method was validated according to the recommendation by the Forensic Isotope Ratio Mass Spectrometry Network (FIRMS). In particular, the linearity test suggested that concentrations of at least 25 mg L−1 and 200 mg L−1 were required to produce reliable δ13C and δ2H values, respectively. Both δ13C and δ2H values were satisfactorily repeatable, reproducible and accurate. As expected, precision and accuracy of the δ2H were lower than those of the δ13C.Finally, the practical applicability of the methods was confirmed by the analysis of 3 lavender and 3 lavandin essential oil samples. We quantified the concentrations of 71 VOCs and the δ13C value of 32 and δ2H value of 30 compounds in real essential oil samples. These preliminary results showed that the combination of GC-MS/MS and GC-IRMS is potentially useful for botanical classification between lavender and lavandin essential oils thus representing an additional powerful tool for assessing the authenticity of commercial essential oils.