Time Of Flight Spectrometry Research Articles

The Effects of Encapsulation on the In Vitro Anti-Clostridial Activity of Olive Mill Wastewater Polyphenolic Extracts: A Promising Strategy to Limit Microbial Growth in Food Systems.

Despite the technologies applied to food production, microbial contamination and chemical deterioration are still matters of great concern. In order to limit these phenomena, new natural approaches should be applied. In this context, the present study aimed to assess the antioxidant and anti-Clostridial effects of two different polyphenolic extracts derived from olive mill vegetation water, one liquid (LE) and one encapsulated (EE). The extracts have been preliminary characterized using Liquid Chromatography Quadrupole Time-Of Flight spectrometry. The Oxygen Radical Absorbance Capacity method was used to determine the antioxidant capacity, registering a higher value for EE compared to that for LE (3256 ± 85 and 2446 ± 13 µgTE/g, respectively). The antibacterial activity against C. perfringens, C. botulinum and C. difficile was studied by the agar well diffusion method, MIC and MBC determination and a time-kill test. The results confirm that EE and LE are able to limit microbial growth, albeit with minor effects when the phenolic compounds are encapsulated. Further studies are needed to evaluate the possible application of these extracts in food systems.

Stopping force of (0.09 – 0.30) MeV/n 22Ti, 24Cr and 28Ni ions in aluminum oxide and titanium oxide thin foils by time of flight spectrometry

The generation of a new set of experimental stopping force data of 22Ti, 24Cr and 28Ni ions through Al2O3 and TiO2 thin films at low energy, is reported here. The thickness of the used target was measured using 1.6 MeV H+ Rutherford Backscattering Spectrometry. The obtained stopping force data are compared with the corresponding computed values from the most widely used Ziegler’s Stopping and Range of Ions in Matter (SRIM) code [1] which is based on semi empirical models and ab initio calculations using Grande and Schiewietz’s Convolution approximation for swift Particles (CasP) code [2]. It can be said that in the light of the obtained results, both SRIM and CasP codes give accurate predictions of experimental stopping force data over the investigated energy range from 0.09 MeV/n to 0.30 MeV/n, where the heavy ions 22Ti, 24Cr and 28Ni are partially stripped.

Diagnostics of target-cavity confined plasmas produced by nanosecond pulsed laser ablation of graphite

Ion energy of laser plasmas produced by repeated nanosecond pulsed laser ablation of graphite is measured by time-of-flight (TOF) spectrometry and retarding potential analysis. An Nd:YAG laser with λ=1064 nm wavelength is incident toward the center of a cylindrical graphite target while the target is rotated along its axis. Ion energy distributions are measured via TOF spectroscopy. TOF signals show a decrease in the ion peak current by half followed by shifting of the signals by 4 μs toward later times after 10 000 laser shots. An ion energy decrease of 200 eV was measured from the retarding potential analysis.

Large Bradbury–Nielsen Gate Optimized for Electrospray Time of Flight Spectroscopy

A large, , low-cost Bradbury–Nielsen gate (BNG) was developed and optimized to reduce diagnostic noise and high-energy ion impingement damage to electrospray thrusters during time-of-flight spectroscopy (TOFS). This new BNG increased diagnostic ion transparency by 633%, significantly increased the signal-to-noise ratio in the raw data collection, and reduced thruster damage due to high-energy ionic bombardment during ion diversion. By deflecting the thruster’s ionic plume, as opposed to the conventional method of reflection, the BNG can be operated at 50–75% lower cyclic voltages, thus reducing high-frequency noise induced by the required high-voltage, high-frequency gate operation. The BNG reduces high-energy ion impingement on the thruster’s extraction surface by up to 98.9%. This significant reduction in return current allows for unaltered measurements of performance and enables repeated diagnostic use without deleterious effects during long test campaigns.

Determining the fuel ion ratio for D(T) and T(D) plasmas at JET using neutron time-of-flight spectrometry

The fusion fuel ion ratio, , is an important plasma parameter that needs to be tuned to maximize the power of a tokamak type fusion reactor. It is recognized as a parameter required for optimizing several ITER operating scenarios, and will likely be continuously monitored in future high-performance fusion devices such as DEMO. Tritium was recently introduced in the Joint European Torus (JET) plasma for the first time since the 1997 DTE1 and 2003 TTE campaigns, enabling the possibility to investigate fuel ion ratios. We present a method for measuring using neutron time-of-flight (TOF) spectrometry. By fitting the measured neutron spectral features, the relative reaction rate intensities between different ion species can be inferred, from which the fuel ion ratio can be extracted for a corresponding modeled reactivity. Unlike previous measurements of using neutron spectrometry, we utilize the neutron energy continuum produced in the three-body TT reaction to determine the fuel ion ratio for plasmas with large concentrations of tritium. Furthermore, the use of neutron TOF spectrometry has never previously been demonstrated for evaluating . The method is applied to TOF spectra acquired with TOFOR (JET name KM11) and shown to be consistent with the optical JET diagnostic KT5P which uses optical spectroscopy of a modified Penning gauge plasma to measure tritium and deuterium concentrations in the divertor exhaust gas.

Time-of-flight photoelectron momentum microscopy with 80-500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter.

The small time gaps of synchrotron radiation in conventional multi-bunch mode (100-500 MHz) or laser-based sources with high pulse rate (∼80 MHz) are prohibitive for time-of-flight (ToF) based photoelectron spectroscopy. Detectors with time resolution in the 100 ps range yield only 20-100 resolved time slices within the small time gap. Here we present two techniques of implementing efficient ToF recording at sources with high repetition rate. A fast electron-optical beam blanking unit with GHz bandwidth, integrated in a photoelectron momentum microscope, allows electron-optical `pulse-picking' with any desired repetition period. Aberration-free momentum distributions have been recorded at reduced pulse periods of 5 MHz (at MAX II) and 1.25 MHz (at BESSY II). The approach is compared with two alternative solutions: a bandpass pre-filter (here a hemispherical analyzer) or a parasitic four-bunch island-orbit pulse train, coexisting with the multi-bunch pattern on the main orbit. Chopping in the time domain or bandpass pre-selection in the energy domain can both enable efficient ToF spectroscopy and photoelectron momentum microscopy at 100-500 MHz synchrotrons, highly repetitive lasers or cavity-enhanced high-harmonic sources. The high photon flux of a UV-laser (80 MHz, <1 meV bandwidth) facilitates momentum microscopy with an energy resolution of 4.2 meV and an analyzed region-of-interest (ROI) down to <800 nm. In this novel approach to `sub-µm-ARPES' the ROI is defined by a small field aperture in an intermediate Gaussian image, regardless of the size of the photon spot.

Phenotypic and Genetic Comparison of a Plant-Internalized and an Animal-Isolated Salmonella Choleraesuis Strain.

Contamination of fresh produce with human pathogens poses an important risk for consumers, especially after raw consumption. Moreover, if microorganisms are internalized, no removal by means of further hygienic measures would be possible. Human pathogenic bacteria identified in these food items are mostly of human or animal origin and an adaptation to this new niche and particularly for internalization would be presumed. This study compares a plant-internalized and an animal-borne Salmonella enterica subsp. enterica serovar Choleraesuis aiming at the identification of adaptation of the plant-internalized strain to its original environment. For this purpose, a phenotypical characterization by means of growth curves under conditions resembling the indigenous environment from the plant-internalized strain and further analyses using Pulsed-field gel electrophoresis and Matrix-assisted laser desorption ionization time of flight spectrometry were assessed. Furthermore, comparative genomic analyses by means of single nucleotide polymorphisms and identification of present/absent genes were performed. Although some phenotypical and genetic differences could be found, no signs of a specific adaptation for colonization and internalization in plants could be clearly identified. This could suggest that any Salmonella strain could directly settle in this niche without any evolutionary process being necessary. Further comparative analysis including internalized strains would be necessary to assess this question. However, these kinds of strains are not easily available.

Optical porosimetry by gas in scattering media absorption spectroscopy (GASMAS) applied to roller compaction ribbons

Currently, there is a need for new technology for in-line or fast at-line assessment of solid material porosity. One specific gap is a fast technology to be used in connection to roller compaction (RC) manufacturing, where the porosity of the RC ribbons is critical to the manufacturing of tablets of the right tensile strength and disintegration properties.In this paper, the development of an at-line technology for fast, non-destructive assessment of porosity of RC ribbons is reported. The technology is based on a diode laser spectroscopic technique called Gas in scattering media absorption spectroscopy (GASMAS). GASMAS measures the sample voids by laser light, giving the distance through air. The total distance the light travels is measured using time-of-flight spectroscopy (TOFS). The ratio of these measures gives an “optical porosity”, which through theory relates to the porosity of the sample.We present a description of the technology, evaluations of measurement robustness and results from an experimental design where roller compactor, roll force, roll gap and formulation were varied. It is concluded that the data from two different pharmaceutical formulations is supported by the same calibration curve, which indicates that optical porosimetry is a general technique for pharmaceutical materials that does not require frequent calibrations.

Characterization of prompt gamma ray emission for in vivo range verification in particle therapy: A simulation study

In this paper we investigate the emission and detection characteristics of prompt gamma (PG) rays for in vivo range verification during hadron therapy, using Geant4 simulations. Proton, 4He and 12C beams of varying energy are incident on water phantoms. The PG production yield, energy spectral characteristics and spatial correlation with the Bragg Peak (BP) have been quantified. Further, the angular distributions for PG detection with respect to a point-of-reference on the phantom surface have been explored. The temporal properties of PG emission and time-of-flight (TOF) of PG detection have also been investigated in correlation with the changing particle beam range. Our results show that the primary PG rays from nuclear interactions of the primary beam exhibit the closest correlation to the beam range but its signal is significantly masked by the concurrent secondary PG rays, particularly for heavier ions such as carbon ion beams. The PG TOF spectroscopy encodes the essential information of the beam range but requires high time resolution measurements to retrieve it. A hybrid PG detection system to utilize the energy, timing and spatial characteristics of PG rays is desirable for BP tracking in real-time.

Fractal diffusion in high temperature polymer electrolyte fuel cell membranes.

The performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range. In order to selectively observe the diffusion of protons potentially contributing to the ion conductivity, two samples were prepared, where in one of the samples the phosphoric acid was used with hydrogen replaced by deuterium. The scattering data from the two samples were subtracted in a suitable way after measurement. Thereby subdiffusive behavior of the proton diffusion has been observed and interpreted in terms of a model of fractal diffusion. For this purpose, a scattering function for fractal diffusion has been developed. The fractal diffusion dimension dw and the Hausdorff dimension df have been determined on the length scales covered in the neutron scattering experiments.

Hyperthermic intracavitary nanoaerosol therapy (HINAT) as an improved approach for pressurised intraperitoneal aerosol chemotherapy (PIPAC): Technical description, experimental validation and first proof of concept.

Background: The delivery of aerosolised chemotherapeutic substances into pressurised capnoperitonea has been reported to be more effective than conventional liquid chemotherapy for the treatment of peritoneal carcinomatosis. However, recent reports reveal limitations of the currently available technology.Material and Methods: A novel approach for pressurised intraperitoneal aerosol chemotherapy (PIPAC), called hyperthermic intracavitary nanoaerosol therapy (HINAT), based on extracavitary generation of hyperthermic and unipolar charged aerosols, was developed. The aerosol size distribution, the spatial drug distribution and in-tissue depth penetration of HINAT were studied by laser diffraction spectrometry, differential electrical mobility analysis, time of flight spectrometry, scintigraphic peritoneography and fluorescence microscopy. All experiments were performed contemporaneous with conventional PIPAC for the purpose of comparison. Furthermore, a first proof of concept was simulated in anesthetised German Landrace pigs.Results: HINAT provides a nanometre-sized (63 nm) unipolar-charged hyperthermic (41 °C) drug aerosol for quasi uniform drug deposition over the whole peritoneum with significantly deeper drug penetration than that offered by conventional PIPAC.

Adhesion of plasma-deposited silicon oxide barrier layers on PDMS containing polypropylene

The adhesion of SiOx coatings deposited by plasma-enhanced chemical vapor deposition onto injection-molded polypropylene (PP) was investigated as function of polypropylene surface Si enrichment. The PP was either used in its original state or was modified by a by-mixture with small amounts of polydimethylsiloxane (PDMS) in the extrusion process. The substrates where characterized by X-ray photoelectron spectroscopy, attenuated infrared reflection and time of flight spectroscopy; it was seen that the PP/PDMS substrates showed a Si-enriched top layer about 1nm thick. The adhesion of the SiOx coatings to the PP/PDMS substrates was greatly enhanced with respect to the non-functionalized PP, which shows that adhesion of plasma-deposited SiOx layers to polymer substrates can be improved without the need to deposit intermediate adhesion layers, and without the need to include a plasma pre-treatment step into the process.

Levels, Sources, and Risk Assessment of Polychlorinated Biphenyls (PCBs) in Soils from Industrial Areas: A Case Study from Saudi Arabia

ABSTRACTThe objective of this study was to assess the pollution levels, sources, and human health risk of polychlorinated biphenyls (PCBs) in soils of industrial areas of the central and eastern regions of Saudi Arabia. Therefore, the surface soil samples from industrial areas (cement kiln, oil refinery, electric power plant, steel industry, and desalination plant) were collected and analyzed by High-Resolution Gas Chromatography-Mass Spectrometry/Mass Spectrometry-Time of Flight (HRGC-MS/MS-TOF) to quantify the levels of 26 PCBs (including 12 dioxin-like PCBs and 14 indicator-PCBs). The investigated 26 PCBs were detected in all soil samples. The total PCBs concentration (from tri-CBs to hepta-CBs) ranged from 171 to 4892 pg g−1 with an average of 1369 pg g−1 in soils of the central region and of 142–1231 pg g−1 with an average of 302 in soils of the eastern region, showing higher values at cement factory and/or oil refinery sites. Overall, the indicator-PCBs were the main congeners and contributed dominantly to the total mass of PCBs in comparison with the dioxin-like PCB congeners, with the most abundant for PCB-180 in the soil samples of the central region. Among individual dioxin-like PCBs, PCB-126 had the highest average value of the toxicity equivalence (TEQ). The TEQ values of ∑12dioxin-like PCBs did not exceed the Canadian soil quality guidelines of dioxin (4 pg TEQ g−1). Based on human health risk assessment via ingestion, dermal contact, and inhalation, low adverse effects of PCBs could be expected as indicated by lower values of cancer risk (≤10−6). The principal component analysis indicated that there is a different source of PCBs with similar or different PCB profiles.

Effect of ambient pressure on a femtosecond laser induced titanium plasma

Femtosecond laser induced Ti plasma has been characterized as a function of pressure by means of femtosecond laser induced breakdown spectroscopy (fs-LIBS). Experiments were performed with a Ti: sapphire laser system (100 fs, 800 nm), in an air pressure from 10 Pa to 104 Pa. The time-resolved spectrum has been acquired and the spectral intensities of different plasma species have been investigated with a changing ambient pressure. The Ti atomic lines decay while the ionic ones grow with an increasing pressure. The enhancement of nitrogen ionic line has also been observed. The time of flight spectroscopy is adopted to measure the expanding velocity of the plasma plume. The increasing pressure slows the plasma expansion along both axial and radial directions. The electron density and temperature are measured by means of Boltzmann plot method and Stark width method, respectively. It is concluded that higher pressure will increase the energy absorption and retard the plasma expansion, leading to larger electron density and temperature.

Neutron time-of-flight spectroscopy measurement using a waveform digitizer**Supported by Strategic Priority Research Program of the Chinese Academy of Science(TMSR) (XDA02010100), National Natural Science Foundation of China(NSFC)(11475245,No.11305239), Shanghai Key Laboratory of Particle Physics and Cosmology (11DZ2260700)

The photoneutron source (PNS, phase 1), an electron linear accelerator (linac)-based pulsed neutron facility that uses the time-of-flight (TOF) technique, was constructed for the acquisition of nuclear data from the Thorium Molten Salt Reactor (TMSR) at the Shanghai Institute of Applied Physics (SINAP). The neutron detector signal used for TOF calculation, with information on the pulse arrival time, pulse shape, and pulse height, was recorded by using a waveform digitizer (WFD). By using the pulse height and pulse-shape discrimination (PSD) analysis to identify neutrons and γ-rays, the neutron TOF spectrum was obtained by employing a simple electronic design, and a new WFD-based DAQ system was developed and tested in this commissioning experiment. The DAQ system developed is characterized by a very high efficiency with respect to millisecond neutron TOF spectroscopy.

Associations of serotonin receptor gene HTR3A, HTR3B, and HTR3A haplotypes with bipolar disorder in Chinese patients.

Single nucleotide polymorphisms (SNPs) in HTR3A and HTR3B have been reported to be associated with bipolar disorder in European and Japanese populations. We explored the roles of 21 tag SNPs in HTR3A and HTR3B in susceptibility to bipolar disorder in a Chinese cohort. Twenty-one Tag SNPs were genotyped in a study consisting of 130 patients with bipolar disorder, who visited Shandong Mental Health Center between June 2013 and May 2014, and 109 healthy individuals as controls. All of the tag SNPs were genotyped using Sequenom MassArray matrix-assisted laser desorption/ionization time of flight spectrometry. Plink 1.07, Haploview 4.2, and SPSS 20.0 were used for the analysis of the genotypes and the associations of the haplotypes with bipolar disorder. Association analyses of tag SNPs detected significant associations with the A allele in HTR3A rs1176719 (P = 0.030) and the C allele in HTR3A rs1176713 (P = 0.048). Haplotype-based association analyses indicated a statistically significant (P = 0.035) five-SNP haplotype (rs1062613:C, rs11604247:C, rs1176722:G, rs2276302:A, rs1176719:G) of linkage disequilibrium in block 3. Analysis of our small Chinese sample revealed a significant association of HTR3A with bipolar disorder, but yielded no evidence of an association between HTR3B and bipolar disorder. Furthermore, evidence for an association was found for a haplotype of HTR3A. Studies with larger Chinese samples are needed to verify our findings.

Kinetic study of the OH, NO 3 radicals and Cl atom initiated atmospheric photo-oxidation of iso-propenyl methyl ether

Abstract Rate coefficients at room temperature and atmospheric pressure for the reaction of isopropenyl methyl ether ( i -PME) (CH 2 C(CH 3 )OCH 3 ), with OH and NO 3 radicals and with Cl atoms have been determined in a 50 L Pyrex glass reaction chamber in conjunction with Fourier Transform Infrared absorption spectroscopy (FTIR) as a detection technique. The chamber is equipped with a White-type multiple-reflection mirror system with a total optical path length of ≈200 m. Additional experiments were carried out using evacuable Teflon-coated bags (volume 150 L) and a gas chromatography/mass spectrometry-time of flight (GC-TOF MS) detection system. This is the first kinetic study carried out to date for these reactions. The rate coefficients k (in units of cm 3 molecule −1 s −1 ) obtained are: (1.14 ± 0.10) × 10 −10 for the OH reaction, (2.41 ± 0.50) × 10 −11 , for the NO 3 reaction and (7.03 ± 0.67) × 10 −10 for the Cl reaction. A mechanism is proposed from the observed reaction products. The atmospheric lifetimes of the studied ether is estimated considering the rate coefficients of the reactions with OH and NO 3 radicals and Cl atom. Calculated atmospheric lifetimes reveal that the dominant loss process for i -PME is clearly the night-time reaction with the NO 3 radical. The radiative efficiency (RE) is obtained from the infrared spectra of the ether and the global warming potential (GWP) is then estimated. Atmospheric implications of the ether emission are discussed.

Electronic stopping power data of heavy ions in polymeric foils in the ion energy domain of LSS theory

A continuous energy loss measurements of 63Cu, 28Si, 27Al, 24Mg, 19F, 16O and 12C ions over an energy range of (0.06–0.65)MeV/nucleon through thin polymeric foils (Mylar, Polypropylene and Formvar) were carried out by time of flight spectrometry. The deduced experimental stopping data have been used in order to assess our proposed semi empirical formula. The proposed approach based on the Firsov and Lindhard–Scharff stopping power models is provided for well describing-the electronic stopping power of heavy ions (3⩽Z<100) in various solids targets at low energy range. The ζe factor, which was approximated to be ∼Z11/6, involved in Lindhard, Scharff and Schiott (LSS) formula has been suitably modified in the light of the available experimental stopping power data. The calculated stopping power values after incorporating, effective charge Z1∗ of moving heavy ions with low velocities (v⩽v0Z12/3) and modified ζe in LSS formula, have been found to be in close agreement with measured values in various solids targets. A reason of energy loss measurements is to obtain data that help to assess our understanding of the stopping power theories. For this, the obtained results are compared with, LSS calculations, MSTAR and SRIM-2013 predictions code.

Stopping force of Ti for 6 ⩽ Z ⩽ 29 ions measured by time of flight spectrometry

Accurate stopping force data is of vital importance in ion beam materials analysis using heavy ion beams. The predictive accuracy of theoretical and semi-empirical formulations can only be improved through continual validation of these codes by making available experimental data from a wide range of projectile-target combinations. In this work stopping force measurements of Ti for 12C, 16O, 24Mg, 27Al and 63Cu ions were carried out by heavy ion Time-of-Flight Elastic Recoil Detection (ToF-ERD) spectrometry and the results are compared with semi-empirical calculations by Ziegler’s Stopping and Range of Ions in Matter (SRIM-2010) code, and ab initio calculations by Grande and Schiewietz’s Convolution approximation for swift Particles (CasP 5.2) code. Both SRIM and CasP underestimate stopping in the energy range studied. SRIM predictions average within 10% of data and CasP calculations range within 5–25% of data.

RAFT polymerization kinetics and polymer characterization of P3HT rod-coil block copolymers

Here an in-depth analysis of reversible addition–fragmentation chain transfer (RAFT) polymerization kinetics is reported in order to provide better definition of poly(3-hexylthiophene) (P3HT) rod–coil block copolymers thru a more thorough understanding of the RAFT polymerization of the coil block. To this end, a new P3HT macroRAFT agent is synthesized and utilized to prepare rod–coil block copolymers with P3HT and poly(styrene), poly(tert-butylacrylate), and poly(4-vinylpyridine), and the RAFT polymerization kinetics of each system are fully detailed. This is achieved by a comprehensive analysis of characterization data from 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption ionization time of flight spectroscopy, which are used as complementary techniques in order to address difficulties in accurately characterizing the synthesized polymer systems. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3575–3585