A data acquisition system for mass‐analyzed ion kinetic energy spectra using a personal computer

A microwave tomography system utilizing an inexpensive data acquisition system is introduced. The data acquisition system comprises several antennas surrounding an object-of-interest, field measuring probes distributed evenly in the measurement chamber, and a lock-in amplifier unit to perform measurements at audio frequencies based on the modulated scatterer technique. Images of different objects are successfully reconstructed using the presented system.

The ion kinetic energy (IKE) and mass spectra of 1- and 2-chloronapthalenes and seven dichoronaphthalenes have been recorded and the spectra of each set of isomers are strikingly similar; comparison of the daughter ion peaks obtained from the IKE spectra indicate chlorine randomisation over at least one of the rings in the monosubstituted compounds and over both rings in the isomeric dichloronaphthalenes.

An inexpensive data acquisition system for a multi-bed intensive care unit

Charge separation of metastable triply charged ions derived from benzo[ a]pyrene

The halogeno-(4-halogenophenyl)arsanyl cations Y–C 6 H 4 As + X (X=F, Cl, Br, I) are abundant in the 70 eV EI mass spectra of dihalogeno-(4-halogenophenyl)arsanes Y–C 6 H 4 AsX 2 . This has been used to study the unimolecular reactions of ions Y–C 6 H 4 As + X by techniques of tandem mass spectrometry with respect to a possible rearrangement to nido-isomers, ñ 4 -(XYC 6 H 4 )As + , in which the As + is capping a dihalogenobenzene moiety, YC 6 H 4 AX. The mass analyzed ion kinetic energy (MIKE) spectra of Y–C 6 H 4 As + X, 1a + –3a + and 5a + (X, Y=F, Cl, Br, see Scheme 2), display broad and even dish-topped peaks for the loss of HX and HY, respectively, indicating a large kinetic energy release ( KER) during these reactions and the presence of a large reverse activation energy. The mean value of the KER, < T>, is specific for the type of the halogen substituent but independent of its original position and is identical to < T> found for the loss of HX or HY from metastable halogeno–phenylarsanyl cations, C 6 H 5 As − X or C 6 H 4 As + Y. These results give strong evidence for a positional change of X and Y in Y–C 6 H 4 As + X before fragmentation, plausibly via intermediate ñ 4 -(XYC 6 H 4 )As + . However, the relative intensities of the signals for loss of HX and HY are different in the MIKE spectra of isomeric arsanyl cations and the spectra of the isomers obtained by collision-induced decomposition show that the metastable arsanyl cations represent a mixture of isomers with the original arsanyl cation prevailing. Clearly, interchange of halogen substituents in Y–C 6 H 4 XAs + is slow compared with fragmentation and the intermediate nido-isomer, ñ 4 -(XYC 6 H 4 )As + , is separated from the isomers of the classical structure of a halogeno-(halogenophenyl)arsanyl cation by substantial activation barriers. Therefore, in the case of 4a + and 6a + (X, Y=Cl, I), any rearrangement is obstructed by the facile loss of the weakly bonded I substituent. This reaction model was verified by theoretical calculations of relevant stationary points of the minimum energy reaction pathways ( MERP) of fragmentation and rearrangement at the level UBHLYP/6-311+g(2d,p)//UBHLYP/6-31+g(d). In particular, the calculations show that the nido isomers, ñ 4 -(XYC 6 H 4 )As + , are stable species but higher in energy than their “classical” isomers.

A data acquisition (DAQ) system for the low velocity impact tests is presented. The DAQ system is comprised of transducers, DAQ card, personal computer and self-manufactured impact equipment. The whole impact signal acquisition system has capability of sampling time history of contact force and optical signal which is employed to calculate the falling velocity, and it also generates the control signal for the equipment which catches the drop-weight after its rebound. The test data are presented, which shows the proposed DAQ system is applicable to the test setup for low velocity impact damage pre-set of composites in the aircraft structural industries.

Relative secondary ion yields and kinetic energy spectra of Tan + ions (n ≤12) sputtered from a tantalum target by Au- atomic ions with energies of 6keVand 12keVas well as by 12keVAu2 - molecular ions have been measured under identical experimental conditions. Under molecular ion bombardment, an anomalous high non-additive sputtering yield was observed for large metal clusters. In this case, for instance, the yield of Ta10 + clusters was determined to be approximately 320 times higher than that under corresponding atomic ion bombardment (6keV per constituent atom of the projectile). Comparison between mass spectra and kinetic energy spectra determined under molecular ion bombardment with those for atomic ion bombardment showed both qualitative and quantitative differences. Taking into account the experimentally observed regularities, a hypothesis regarding the existence of two different cluster ion emission mechanisms for small clusters (n 5) has been proposed.

Cyclic nucleotides are biochemical second messengers which mediate the actions of many hormones and neurotransmitters. Fast‐atom bombardment (FAB) mass spectrometry and mass‐analysed ion kinetic energy (MIKE) spectra have provided a means of unambiguous identification of these compounds, and in addition to identifying endogenous putative cyclic nueleotides and their synthetic analogues FAB/MIKE analysis has now been applied to good effect to both qualitative and quantitative studies of cyclic nuclcotide‐related enzymes. Here the application of this mass spectrometric technique to cyclic nucleotides is described and its impact upon this field reviewed.

The eliminations of methanol (CH3OH) and formaldehyde (CH2O) molecules from the molecular ion of 1,2-dimethoxyethane have been investigated by using deuterium labelling technique and mass analyzed ion kinetic energy (MIKE) spectra. The MIKE spectra show that the structure of the resultant ion at m/z 58, [M-CH3OH]+., is identical with that of the molecular ion of methyl vinyl ether ([CH3OCH=CH2]+.), and that of the ion at m/z 60, [M-CH2O]+., is an oxonium type ion, [CH3O(H)CH2CH2.)]+. The hydrogen rearrangements associated with these reactions result in thermochemical stabilization in the product systems. The loss of CH3OH molecule is accompanied by a kinetic energy release (T0.5 = 101 meV) larger than that in the elimination of CH2O molecule (T0.5=17 meV). A significant isotope effect is observed in the methanol and formaldehyde losses from deuterated 1,2-dimethoxyethane CH3OCH2CD2OCD3 (2,5-dioxahexane-1,1,1,3,3-d5). These results are discussed along with mechanistic features of both reactions.

The electron ionization and chemical ionization mass spectrometry of some diastereomeric β‐hydroxy‐γ‐fluoro alkyl aryl sulphoxides is described and the mechanisms of the common fragmentation patterns are discussed with the aid of linked scans at constant B/E and at constant B 2 /E, mass‐analysed ion kinetic energy spectra and labelling experiments.

A versatile and flexible data acquisition system KODAQ (Kakuken Online Data AcQuisition system) has been developed. The system runs with CAMAC and the NEC PC9801, which is similar to the IBM PC/AT. The system is designed to set up a data acquisition system for various kinds of nuclear physics experiments. For small-scale experiments, the system should be adequate in processing capacity. It has a good cost performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A prototype of Electroencephalography (EEG) data acquisition system based on Raspberry Pi 3 model B and ADS1299EEGFE-PDK (Texas Instruments) has been developed. This system is compact, cost effective, and has high levels of accuracy and portability. This system has feature of relative power ratio (RPR) for further processing purposes. The analog front end (AFE) board consists of ADS 1299 chip with features of simultaneous eight-channels ADC, 24 bits resolution, low power, low noise. The data acquisition system was configured with 4 units of AFE board using Daisy-Chain method via Serial Peripheral Interface (SPI) and processed based on Raspberry. The data command of AFE were set using RDATA format. The data acquisition system using C for data acquired and MATLAB for signal processing. The RPR were calculated in real-time using FFT. The acquired and processed data would be sent to HDMI and to a Personal Computer (PC) if needed by users. The performance of this system was evaluated using EEG simulator (NETECH Mini-Sim EEG) that generate sinusoidal electrical signal with frequency 2 Hz, 5 Hz, and also voltage amplitude of 100 µV, 500 µV.

Abstract[M  H+]− ions of isoxazole (la), 3‐methylisoxazole (1b), 5‐methylisoxazole (1c), 5‐phenylisoxazole (1d) and benzoylacetonitrile (2a) are generated using NICI/OH− or NICI/NH2− techniques. Their fragmentation pathways are rationalized on the basis of collision‐induced dissociation and mass‐analysed ion kinetic energy spectra and by deuterium labelling studies. 5‐Substituted isoxazoles 1c and 1d, after selective deprotonation at position 3, mainly undergo N  O bond cleavage to the stable α‐cyanoenolate NC  CH  CR  O− (R = Me, Ph) that fragments by loss of RCN, or RH, or H2O. The same α‐cyanoenolate anion (R = Ph) is obtained from 2a with OH−, or NH2−, confirming the structure assigned to the [M  H+]− ion of 1d, On the contrary, 1b is deprotonated mainly at position 5 leading, via NO and C(3)C(4) bond cleavages, to HC ≡ C O − and CH3CN. Isoxazole (1a) undergoes deprotonation at either position and subsequent fragmentations. Deuterium labelling revealed an extensive exchange between the hydrogen atoms in the ortho position of the phenyl group and the deuterium atom in the α‐cyanenolate NC  CD = CPh  O−.

The mass spectra of five sets of stereoisomers possessing an eburnane basic skeleton (vincamine, vincaminic acid ethyl ester, deoxyvincamine, deoxyvincaminic acid ethyl ester, apovincaminic acid ethyl ester and all their possible epimers) have been compared. All of the epimers, among them the 3H‐β isomers, not studied formerly, have characteristically different electron impact spectra. For vincamine and its epimers similar differences were also found in the argon charge exchange ionization, mass‐analysed ion kinetic energy and collisionally activated mass‐analysed ion kinetic energy spectra. The main effects of stereoisomers on the abundance ratios clearly indicated the occurrence of some highly stereospecific or stereoselective decomposition processes. Conclusions concerning the mechanism of these reactions, based on the normal and metastable ion spectra as well as on some energetic data for the epimers, have also been drawn. For several fragment ions the observed unexpected abundance differences seem to be rationalized in terms of the competing effects of other decomposition processes of higher stereoselectivity.

Primary fragmentation reactions in benzohydroxamic and benzothiohydroxamic acids have been studied and compared with those in benzamides and benzothioamides. Mass‐analysed ion kinetic energy spectra, collisional activation spectra and spectral data from labelled compounds were used to elucidate fragment ion structures and reaction mechanisms. The mass spectra are shown to be dependent on ion source temperature. Losses of O and H2O are proved to be thermal in origin. The formation of an S… HO bond, which is analogous to an intramolecular hydrogen bond in solution chemistry, directs many fragmentation pathways. This seems to be the major factor determining the differences between the mass spectra of benzothiohydroxamic acids and those of the corresponding carbonyl compounds.