Total Number Of Charges Research Articles

Current Insights into the Molecular Mechanisms of VDAC-Tubulin Interaction

Voltage-dependent anion channel (VDAC), the major channel of the mitochondrial outer membrane, serves as a principal pathway for ATP, ADP, and other respiratory substrates across this membrane. Recently, we found that free dimeric tubulin induces highly efficient reversible blockage of VDAC reconstituted into planar lipid membranes. Although the tubulin-blocked state is still conductive for small ions, it has reduced dimensions compared with open state, reversed ionic selectivity, and most importantly is virtually impermeable for ATP. We proposed that by blocking VDAC permeability, tubulin controls mitochondrial respiration. We suggested a model of VDAC-tubulin interaction where the negatively charged C-terminal tail (CTT) of tubulin partially blocks VDAC pore. The corresponding effective “gating charge” of the blockage is impressively high of about 10-14 elementary charges, which compares well with the gating charge of the most voltage-sensitive channels. Surprisingly, this gating charge only mildly depends on salt concentration and significantly exceeds the total number of negative charges of tubulin CTT. This indicates the applied field interacts not only with CTT but also with VDAC charges and dipoles, with all of them contributing to the effective gating charge. Our results also demonstrate that additional steps are involved in the blockage process. We found that lipid-dependent tubulin binding to the membrane greatly impacts VDAC blockage by tubulin. At 100 mM KCl, the charged lipids significantly affect the conductance of the tubulin-blocked state and the on-rate the blockage, but even at 1 M KCl the lipids with different non-lamellar tendencies were shown to change the on-rate by two orders of magnitude. These data allowed us to conclude that hydrophobic interactions between the tubulin and the membrane represent an essential component of the multistep process of VDAC blockage by tubulin, providing a new instructive example of lipid-controlled protein-protein interactions.

Influence of particle location on the number of charges per charged nanoparticle at the outlet of a needle charger

This study has investigated numerically the influence of particle location on the number of charges per charged particle in the 10–40 nm size range at the outlet of a needle charger by simulating flow field, electric field, particle charging, and particle trajectory at various conditions. The results show that the total (i.e., diffusion + field charging) number of charges per particle increase with decreasing ratio values of radial location at the outlet of the charger due to the particle position close to the needle tip. It has also been shown that in the outlet region of the charger there is a critical radial location at which the number of charges per particle is a maximum; this critical radial location represents the point at which the charged particle trajectory becomes closest to the needle electrode. The maximum value of number of charges increases with increasing Reynolds number and slightly increases with decreasing applied voltage for particle diameter larger than 20 nm. The maximum number of charges per charged nanoparticle increases with increasing particle diameter. In addition, the minimum ratio value of radial particle location decreases with increasing Reynolds number for various particle diameters. Implications: In this work, the influence of particle location on the number of charges per charged nanoparticle at the outlet of a needle charger has been investigated using numerical models under different conditions. The results demonstrate that the radial location affects the number of charges per particle at the outlet of the charger. The maximum number of charges increases with increasing particle diameter, and the minimum ratio value of radial particle location decreases with increasing Reynolds number. The numerical models explain and quantify the number of charges on the charged particle in the 10–40 nm size range from the outlet of the needle charger at various conditions.

Modulation of Electroosmotic Flow Using Polyelectrolyte Brushes: A Molecular Dynamics Study

AbstractPolyelectrolyte brushes grafted on a pair of parallel nanochannel walls can affect the electroosmotic flow (EOF) significantly. A molecular dynamics simulation method is used to investigate the relationship between charge distribution on polyelectrolyte brushes and EOF parameters such as flux, velocity, and density of particles. The EOF can be modulated by changing the step between two charged beads on the same chain, Sc, and the valence of a bead, Nc. Simulation results indicate that the flux increases as the total number of charges on the brushes increases. The decrease of Sc and Nc can lead to a maximum average velocity in the center region. The influence on density of particles is also analyzed.magnified image

Layer Charge Density of Smectites — Closing the Gap Between the Structural Formula Method and the Alkyl Ammonium Method

AbstractThe layer charge density (LCD) of montmorillonite represents the permanent negative charge, its most important property. The LCD can be determined by two different methods, the structural formula method(SF M) and the alkylammonium method (AAM). Other methods of determining the LCD are calibrated against one or the other of these. The results of the two methods differ systematically: SFM values are larger than AAM values and the difference increases with increasing layer charge density. In the present study, the critical parameters of both methods were considered quantitatively in order to identify the most likely reason for the systematic difference. One particularly important argument against the validity of the SFM is that typical SFM values correspond to unrealistically large CEC values that have never been reported. In addition, SFM does not consider the variable charge which causes cations to be adsorbed to the outer surface (at pH >4). In contrast to minor constituents, which can of course also affect SFM values, the variable charge can explain only part of the systematic difference. The exchange of pure smectite samples with both Cu-trien andalkyla mmonium revealedthe presence of non-exchangeable, nonstructural cations (Na, K, Ca). These cations, together with 10% (or more) variable charge, may explain the differences in LCD values. The non-exchangeable, non-structural cations could stem from undetected traces of feldspar or volcanic glass. The present samples indicated that the systematic difference in LCD values between the two methods is related to the amount of non-exchangeable, non-structural cations only, indicating that the two LCD methods probe different features of smectites. Using the SFM on pure smectite provides a value for the total number of charges (permanent with andwithout fixed (= non-exchangeable, non-structural) cations plus variable charge). The AAM, on the other hand, provides the charge density of the exchangeable cations (without variable charge).

Redesign of a Plugged β-Barrel Membrane Protein

The redesign of biological nanopores is focused on bacterial outer membrane proteins and pore-forming toxins, because their robust β-barrel structure makes them the best choice for developing stochastic biosensing elements. Using membrane protein engineering and single-channel electrical recordings, we explored the ferric hydroxamate uptake component A (FhuA), a monomeric 22-stranded β-barrel protein from the outer membrane of Escherichia coli. FhuA has a luminal cross-section of 3.1 × 4.4 nm and is filled by a globular N-terminal cork domain. Various redesigned FhuA proteins were investigated, including single, double, and multiple deletions of the large extracellular loops and the cork domain. We identified four large extracellular loops that partially occlude the lumen when the cork domain is removed. The newly engineered protein, FhuAΔC/Δ4L, was the result of a removal of almost one-third of the total number of amino acids of the wild-type FhuA (WT-FhuA) protein. This extensive protein engineering encompassed the entire cork domain and four extracellular loops. Remarkably, FhuAΔC/Δ4L forms a functional open pore in planar lipid bilayers, with a measured unitary conductance of ∼4.8 nanosiemens, which is much greater than the values recorded previously with other engineered FhuA protein channels. There are numerous advantages and prospects of using such an engineered outer membrane protein not only in fundamental studies of membrane protein folding and design, and the mechanisms of ion conductance and gating, but also in more applicative areas of stochastic single-molecule sensing of proteins and nucleic acids.

Inversion Layer Effective Mobility Model for Pocket Implanted Nano Scale n-MOSFET

Carriers scattering in the inversion channel of n- MOSFET dominates the drain current. This paper presents an ef- fective electron mobility model for the pocket implanted nano scale n-MOSFET. The model is developed by using two linear pocket profiles at the source and drain edges. The channel is divided into three regions at source, drain and central part of the channel region. The total number of inversion layer charges is found for these three regions by numerical integration from source to drain ends and the number of depletion layer charges is found by using the effective doping concentration including pocket doping effects. These two charges are then used to find the effective normal electric field, which is used to find the effective mobility model incorporating the three scattering mechanisms, such as, Coulomb, phonon and surface roughness scatterings as well as the ballistic phenomena for the pocket implanted nano-scale n-MOSFET. The simulation results show that the derived mobility model produces the same results as found in the literatures.

Peculiarity of Low Density Plasma-Assisted Charge Emission Produced at LATGS Crystal Surface

Time and energy distribution measurements for a weak plasma-assisted electron and ion emission, initiated at the surface of L-α alanine doped TGS (LATGS) single crystals by a drive ac (500 Hz) electric field exceeding 5 × 103 V/cm, have been performed especially at temperatures below as well as above phase transition. Time spectra of charges obtained at temperatures below phase transition are considerably different than that detected above phase transition; total number of charges registered under switching conditions is about an order higher than that produced during mere charging of the sample; time dependent energy spectra involve charges (electrons and ions) with energies up to a few hundreds of eV.

The β-Sheet Structure pH Dependence of the Core Fragments of β2-Microglobulin Amyloid Fibrils

Abstract Amyloid fibril structures of peptides having the sequence of the #20–41 region of β2-microglobulin (β2m20–41 and β2m21–29) were investigated with FTIR microscope spectroscopy. pH dependence of the amide I band of the IR absorption spectra was analyzed. For β2m20–41, the β-sheet content at pH 6.0 was 55% (12.1 residues) and the β-sheet was located in the N21–G29 and I35–V37 regions, but at pH 2.5 it was 60% (13.1 residues) and located in the F22–V27 and P32–V37 regions. The two structures with different amounts of β-sheet were switched at pH 4.5, which was close to the pI of this sequence (ca. 4.3) rather than the pKa of the carboxyl groups (5.8 ± 0.3 and 3.3 ± 0.4), suggesting the importance of the total number of charges rather than protonation of specific residue(s). The spectral characteristics of the IR linear dichroism and 13C isotope labeling indicated the formation of parallel β-sheet structure in both regions, and the stacking direction was unaltered by pH change. Unexpectedly however, the IR spectra of the β2m21–29 fibril demonstrated the simultaneous presence of parallel/anti-parallel β-sheets. The relevance of the pH dependence of the β2m20–41 fibril structure to that of β2m fibrils is discussed.

Monte Carlo simulations of complex formation between a mixed fluid vesicle and a charged colloid

Monte Carlo simulations are employed to investigate the ability of a charged fluidlike vesicle to adhere to and encapsulate an oppositely charged spherical colloidal particle. The vesicle contains mobile charges that interact with the colloid and among themselves through a screened electrostatic potential. Both migration of charges on the vesicle surface and elastic deformations of the vesicle contribute to the optimization of the vesicle-colloid interaction. Our Monte Carlo simulations reveal a discontinuous wrapping transition of the colloid as a function of the number of charges on the vesicle. Upon reducing the bending stiffness of the vesicle, the transition terminates in a critical point. At large electrostatic screening length we find a reentrant wrapping-unwrapping behavior upon increasing the total number of charges on the vesicle. We present a simple phenomenological model that qualitatively captures some features of the wrapping transition.

Synthesis and Characterization of Novel Functional Electrosterically Stabilized Colloidal Particles Prepared by Emulsion Polymerization Using a Strongly Ionized Amphiphilic Diblock Copolymer

Amphiphilic diblock copolymers such as poly(styrene)-block-poly(styrene sulfonate) (PS-b-PSS) (Matsuoka, H.; Maeda, S.; Kaewsaiha, P.; Matsumoto, K. Langmuir 2004, 20, 7412), belong to a class of new polymeric surfactants that ionize strongly in aqueous media. We investigated their self-assembly behavior in aqueous solutions and used them as an emulsifier to prepare electrosterically stabilized colloidal particles of different diameters between 70 to 400 nm. We determined the size, size polydispersity, effective charge, total dissociable charge, structural ordering, and phase behavior using light scattering, transmission electron microscopy (TEM), small-angle neutron scattering (SANS), and potentiometric titration. These experiments clearly demonstrated that all of the synthesized particles were nearly monodisperse (polydispersity index<or=6%). The results of DLS and TEM clearly suggested the existence of hairy particles. The form factors obtained by SANS were well described by a polydisperse sphere model. The estimated total number of dissociable charges per particle was found to be larger than 10(4)e, whereas the effective charges per particle were found to be around 1000e. This significant difference suggested the confinement of charges inside the corona regions of the polyelectrolyte brush shell. Finally, these monodisperse particles were found to self-assemble into 3D ordered colloidal crystalline arrays at a low volume fraction (=0.00074) that diffract light in the visible region.

Self-Report Measures of Child and Adolescent Psychopathy as Predictors of Offending in Four Samples of Justice-Involved Youth

The authors examined the relation between self-report psychopathy measures and official records of offending in four samples of justice-involved youth (total N = 447). Psychopathy measures included the Antisocial Process Screening Device (APSD) and a modified version of the Childhood Psychopathy Scale (mCPS). Measures of offending included the total number of preadmission arrest charges for three samples (n = 392) and the total number of offenses in the year following release for two samples (n = 138). Neither measure was a strong correlate of preadmission offenses. Although mCPS scores were associated with postrelease offending in one sample, effects for the APSD were observed only when reoffending was conceptualized as a dichotomous variable, indicating a lack of robustness in this association. The findings suggest caution in the use of self-report measures of psychopathic features for decision making with respect to issues of delinquency risk among justice-involved youth.

Implementation of a Handheld Electronic Point-of-Care Billing System Improved Efficiency in the Critical Care Unit

Coding and billing are time consuming and important considerations for critical care practitioners. A 1-year prospective, observational study incorporated the use of a personal digital assistant and MDeverywhere software (Hauppauge, New York) for patient coding and billing. Twelve months of data were examined before electronic implementation (pre-elec) and compared with a 12-month period after implementation (post-elec) by using an unpaired t test or z test with P < .05 considered significant. The total number of charges was 2479 pre-elec and 2243 post-elec. The days from date of service to billing for services significantly decreased from 37.8 pre-elec to 12.4 post-elec (P < .001); days in accounts receivable significantly decreased from 92.0 to 73.0 (P < .001). The net collection rate increased from 44.7% pre-elec to 49.3% post-elec (P < .001). Duplicate charges significantly decreased from 5.0% pre-elec to 1.4% post-elec ( P < .001). The return on investment was 1.97-fold (197%). The initiation of personal digital assistant technology to facilitate billing and coding resulted in significant improvements.

Trends in the Inpatient Mental Health Treatment of Children and Adolescents in US Community Hospitals Between 1990 and 2000

Previous work has demonstrated marked changes in inpatient mental health service use by children and adolescents in the 1980s and early 1990s, but more recent, comprehensive, nationally representative data have not been reported. To describe trends in inpatient treatment of children and adolescents with mental disorders between 1990 and 2000. Analysis of the Healthcare Cost and Utilization Project Nationwide Inpatient Sample, a nationally representative sample of discharges from US community hospitals sponsored by the Agency for Healthcare Research and Quality. Patients aged 17 years and younger discharged from US community hospitals with a principal diagnosis of a mental disorder. Changes in the number and population-based rate of discharges, total inpatient days and average length of stay, charges, diagnoses, dispositions, and patient demographic and hospital characteristics. Although the total number of discharges, population-based discharge rate, and daily charges did not significantly change between 1990 and 2000, the total number of inpatient days and mean charges per visit each fell by approximately one half. Median length of stay declined 63% over the decade from 12.2 days to 4.5 days. Declines in median and mean lengths of stay were observed for most diagnostic categories and remained significant after controlling for changes in background patient and hospital characteristics. Discharge rates for psychotic and mood disorders as well as intentional self-injuries increased while rates for adjustment disorders fell. Discharges to short-term, nursing, and other inpatient facilities declined. The period between 1990 and 2000 was characterized by a transformation in the length of inpatient mental health treatment for young people. Community hospitals evaluated, treated, and discharged mentally ill children and adolescents far more quickly than 10 years earlier despite higher apparent rates of serious illness and self-harm and fewer transfers to intermediate and inpatient care.

Spectroscopic Investigation of Cationic Comb-Type Copolymers/DNA Interaction: Interpolyelectrolyte Complex Enhancement Synchronized with DNA Hybridization

We have demonstrated that cationic comb-type copolymers consisting of a polycation backbone and abundant grafts of water-soluble polymers stabilize DNA hybrids. Furthermore, the copolymers were found to accelerate strand exchange reaction between a double-stranded DNA and its complementary single-stranded DNA. In this article, we investigated the effects of PLL-g-Dex on base pairs of a self-complementary DNA octamer, d(GGAATTCC). The soluble interpolyelectrolyte complex (IPEC) between the DNA and copolymer allowed us to characterize the complex by using spectroscopic methods under physiological ionic condition. Chemical shifts of nucleobase proton signals were not changed by PLL-g-Dex. Furthermore, the copolymer slightly changed the von't Hoff DeltaH accompanying the helix-coil transition of the octamer. These results indicated that the base pairs of the duplex DNA in the IPEC were not perturbed by the polycationic copolymer. It was obviously shown by temperature dependencies of proton and phosphorus NMR spectra that DNA/copolymer interaction was considerably enhanced in response to ds DNA formation. An increase in the density and total number of DNA negative charges upon hybrid formation likely caused the higher affinity of the copolymer with the ds form over that of the copolymer with the ss form. The IPEC formation of CCCs with DNA, however, seems highly sensitive to the coil-helix transition of the DNA.

The relative validity of psychopathy versus risk/needs‐based assessments in the prediction of adolescent offending behaviour

Purpose. The predictive validity of the psychopathy checklist‐youth version (PCL:YV) and Youth Level of Service/Case Management Inventory (YLS/CMI) for juvenile offenders were compared to examine whether a broad needs–risk tool predicted violence better than a focused individual assessment of psychopathy.Methods. 94 adolescents from residential and secure units were interviewed and assessed using the PCL:YV and YLS/CMI. Total scores were retrospectively applied to staff‐recorded incidents of violence, total number of charges and convictions and formally recorded assaults. The predictive accuracy of each tool was assessed using correlational and receiver operator characteristic analyses.Results. The PCL:YV was a better predictor of staff‐recorded violence than the YLS/CMI; both instruments were similar in their ability to predict total number of charges and convictions and assaults. When subdivided by gender, the correlations for predicting staff recorded violence in male participants were significantly higher than for female participants for both test instruments. Both instruments were broadly equivalent in their association with assaults and charges and convictions by gender.Conclusion. The PCL:YV is a better predictor of recorded violence than the YLS/CMI, but for charges and convictions and assaults, the YLS/CMI and PCL:YV were comparable for UK adolescent offenders. When recalculated to exclude the likelihood of predictor–criterion overlap, the results were the same. These findings are discussed in relation to the value of using risk–needs assessment instruments as compared with scales with a more psychopathological and personality focus.

Salting the Charged Surface: pH and Salt Dependence of Protein G B1 Stability

This study shows significant effects of protein surface charges on stability and these effects are not eliminated by salt screening. The stability for a variant of protein G B1 domain was studied in the pH-range of 1.5–11 at low, 0.15 M, and 2 M salt. The variant has three mutations, T2Q, N8D, and N37D, to guarantee an intact covalent chain at all pH values. The stability of the protein shows distinct pH dependence with the highest stability close to the isoelectric point. The stability is pH-dependent at all three NaCl concentrations, indicating that interactions involving charged residues are important at all three conditions. We find that 2 M salt stabilizes the protein at low pH (protein net charge is +6 and total number of charges is 6) but not at high pH (net charge is ≤−6 and total number of charges is ≥18). Furthermore, 0.15 M salt slightly decreases the stability of the protein over the pH range. The results show that a net charge of the protein is destabilizing and indicate that proteins contain charges for reasons other than improved stability. Salt seems to reduce the electrostatic contributions to stability under conditions with few total charges, but cannot eliminate electrostatic effects in highly charged systems.

Low Back Pain in Older Adults: Are We Utilizing Healthcare Resources Wisely?

1) To examine recent change in prevalence and Medicare-associated charges for non-invasive/minimally invasive evaluation and treatment of nonspecific low back pain (LBP); and 2) to examine magnetic resonance imaging (MRI) utilization appropriateness in older adults with chronic low back pain (CLBP). Two cross-sectional surveys of 1) national (1991-2002) and Pennsylvania (2000-2002) Medicare data; and 2) patients aged >or= 65 years with CLBP. Outpatient data. Patients aged >or= 65 years with LBP. Study 1: Outpatient national and Pennsylvania Part A Medicare data were examined for number of patients and charges for all patients, and for those with nonspecific LBP. Total number of visits and charges for imaging studies, physical therapy (PT), and spinal injections was also examined for Pennsylvania. Study 2: 111 older adults with CLBP were interviewed regarding presence of red flags necessitating imaging and history of having a lumbar MRI, neurogenic claudication (NC), and back surgery. Study 1: Between 1991 and 2002, there was a 42.5% increase in total Medicare patients, 131.7% increase in LBP patients, 310% increase in total charges, and 387.2% increase in LBP charges. In Pennsylvania (2000-2002), there was a 5.5% increase in LBP patients and 33.2% increase in charges (0.2% for PT, 59.4% for injections, 41.9% for MRI/CT, and 19.3% for X rays). Study 2: None of the 111 participants had red flags and 61% had undergone MRIs (29% with NC, 24% with failed back surgery syndrome). LBP documentation and diagnostic studies are increasing in Medicare beneficiaries, and evidence suggests that MRIs may often be ordered unnecessarily. Injection procedures appear to account for a significant proportion of LBP-associated costs. More studies are needed to examine the appropriateness with which imaging procedures and non-invasive/minimally invasive treatments are utilized, and their effect on patient outcomes.

Survey of Academic Pediatric Emergency Departments Regarding Use of Evaluation and Management Codes

The aims of the study were to determine the frequency at which each emergency medicine evaluation and management (E/M) code is used, to identify factors associated with their use by academic pediatric emergency departments (PEDs), and to compare PED E/M code utilization rates with rates reported by Centers for Medicare and Medicaid Services for general emergency departments (EDs). A 24-question survey was sent to 42 academic PED medical directors. Questions pertained to PED demographics, physician staff, records/documentation, billing education, and E/M coding data for 1 year. The general ED E/M code utilization rates were obtained from the published Centers for Medicare and Medicaid Services database. Descriptive statistics and odds ratios were used to report and compare the data. Twenty (48%) of the surveys were returned, and 9 (21%) completed the E/M coding data questions. From these 9 departments, the mean PED annual census was 46,065 (range, 23,531-92,910). The methods of PED medical record documentation were template (6), handwritten (2), and dictation/transcription (1). Charge documents were completed by the PED physician (3), professional service coders (4), and hospital coders (2). Coding/documentation in-services were provided to the physicians of 7 PEDs, and billing audits were performed in 5 PEDs. The total number of charges for the 9 PEDs was 325,129, 78.4% of the census. Multiple reasons were given for the discrepancy between census and charges. The percentage of each of the 5 levels of service billed was calculated for each of the 9 PEDs. The 2 lowest levels of service were used 38.3% of the time, whereas the 2 highest were used 19.2% of the time. The range for the highest level of service varied widely from 5.3% to 53.3%. Approximately 65% of E/M codes used by general EDs were for the 2 highest levels of service. The PED with the highest percentage of upper level charges (53.4%) was the only PED that used dictation/transcription for documentation. Although the response rate was low, and thus the validity of the results was limited, the findings may serve as a benchmark for E/M code utilization in PEDs. The large variation in use of the E/M codes among the PED in our study and the lower rate of using the highest E/M codes by the PEDs compared with the general EDs suggest potential opportunities for academic PEDs to improve billing practices.

Inhibition of Furin by Polyarginine-containing Peptides: NANOMOLAR INHIBITION BY NONA-d-ARGININE

Polyarginine-containing peptides represent potent inhibitors of furin, a mammalian endoprotease that plays an important role in metabolism, activation of pathogenic toxins, and viral proliferation. The therapeutic use of D-polyarginines is especially interesting because they are not cleaved by furin and possess inhibitory potency almost equal to L-polyarginines. In this study we attempted to determine the important elements within polyarginines that contribute to effective inhibition. Structure-function analyses of polyarginine peptides showed that inhibition by polyarginine-containing peptides appeared to depend on the total number of basic charges of the positively charged inhibitors bound to the negatively charged substrate binding pocket; peptide positioning did not appear to be rigorously determined. Screening of L- and D-decapeptide positional scanning combinatorial peptide libraries indicated a preference for basic residues in nearly all positions, similar to previous results with hexapeptide libraries. Length and terminal modification studies showed that the most potent D-polyarginine tested was nona-D-arginine (D9R) amide with a K(i) of 1.3 nm. D9R amide was shown to protect RAW264.7 cells against anthrax toxemia with an IC(50) of 3.7 microm. Because of its high stability, specificity, low toxicity, small molecular weight, and extremely low K(i) against furin, D9R amide or its derivatives may represent promising compounds for therapeutic use.

Use of statistical methods for estimation of total number of charges in a mass spectrometry experiment.

Estimation of the number of ions in a mass spectrometry experiment is needed to determine instrumentation parameters such as ionization efficiency, collision-induced dissociation efficiency, ion-transfer efficiency, ion trapping efficiency, and preamplifier detection limit. This work aims at analyzing the statistical characteristics (primarily variance) in the intensities of the isotopic distributions, which depend on the number of ions in the cell. A mathematical derivation was developed based on the maximum likelihood estimation method, which estimates the most likely number of ions in the cell using a method known as nonrandom parameter estimation. The performance of the method improves with increase in the number of observed distributions. The method works well provided the spectra show isotopic resolution and is independent of the instrument or method used to arrive at the spectra.