Fortran IV programs for the penultimate copolymerization model

Three programs have been written for calculations involving use of the penultimate copolymerization model. The first computes the penultimate reactivity ratios from composition-conversion data, without constraints, at any conversion. A nonlinear leastsquares technique using Marquardt's algorithm is employed. The second program computes the four optimum starting monomer feed ratios, M₁⁰/M₂⁰ which should be used by the experimenter from the penultimate reactivity ratios. These optimum feed ratios are obtained by choosing the conditions necessary to minimize the determinant of the variance-covariance matrix. The input for the first program includes estimates of known values of the penultimate reactivity ratios. By using these two programs sequentially the experimenter has an optimized experimental approach toward evaluating penultimate reactivity ratios at any conversion. Finally, a program has been provided to calculate composition–conversion data, given penultimate reactivity ratios.     

Polymers derived from fluoroketones. I. Preparation of fluoroalkyl acrylates and methacrylates

The preparation and physical properties of some perhaloalkyl acrylate and methacrylate esters are discussed. In the synthetic route to the perhaloalkyl esters, acryloyl or methacryloyl chloride is made to react with a metal fluoride—perhaloketone adduct. A side reaction which accompanies esterification is the formation of acryloyl or methacryloyl fluoride. Possible mechanisms for the formation of acyl fluoride and ester are considered. Evidence is presented which suggests that acyl fluoride formation may occur by a breakdown of the fluoroalkyl esters through an intramolecular fluorine shift.     

Ion mobility spectrometry as flow-injection detector and continuous flow monitor for aniline in hexane and water

Ion mobility spectrometry (IMS) was used as a flow-injection detector to quantitatively examine the ionization chemistry of aniline in hexane. A 5-microl sample was vaporized at 15-90-sec intervals in a flowing air stream and analyzed with an IMS equipped with acetone reactant ion chemistry, ambient temperature drift tube and membrane-based inlet. Precision was 3-11% relative standard deviation for 1-100 ppm aniline in hexane with 90-sec injection intervals and detection limits were ca. 0.5 ppm with 5-microl injections. Matrix effects with amine and organic solvent mixtures were observed and corrected for low and medium proton affinity interferences with standard addition methods. Pronounced fouling of the IMS occurred when a continuous water flow was introduced for aqueous flow injection-IMS. Continuous water monitoring without degraded IMS performance was possible by sampling air flow through a Silastic tube immersed in an aqueous sample.     

Radical-initiated homo- and copolymerization of α-methylene-γ-butyrolactone

The kinetics of α-methylene-γ-butyrolactone (α-MBL) homopolymerization was investigated in N,N-dimethylformamide (DMF) with azobis(isobutyronitrile) as initiator. The rate of polymerization (R_p) was expresed by R_p = k[AIBN]^0.54[α-MBL]^1.1 and the overall activation energy was calculated as 76.1 kJ/mol. Kinetic constants for α-MBL polymerization were obtained as follows: k_p/k_t^1/2 = 0.161 L^1/2 mol^?1/2·s^?1/2; 2fk_d = 2.18 × 10^?5 s^?1. The relative reactivity ratios of α-MBL(M₂) copolymerization with styrene (r₁ = 0.14, r₂ = 0.87) were obtained. Applying the Q–e scheme led to Q = 2.2 and e = 0.65. These Q and e values for α-MBL are higher than those for MMA     

Radical-initiated homo- and copolymerization of cyanomethyl methacrylate

The kinetics of cyanomethyl methacrylate (CyMA) homopolymerization was investigated in acetonitrile with azobisisobutyronitrile as initiator. The rate of polymerization R_p was expressed by R_p = k[AIBN]^0.49[CyMA]^1.2 and the overall activation energy was calculated as 72.3 kJ/mol. Kinetic constants for CyMA polymerization were obtained as follows: k_p/k = 0.10 L^1/2s^?1/2; 2fk_d = 1.57 × 10^?5s^?. The relative reactivity ratios of CyMA(M₂) copolymerization with styrene (r₁ = 0.15, r₂ = 0.29) and methyl methacrylate (r₁ = 0.43, r₂ = 0.75) in acetonitrile were obtained. Applying the Q-e scheme (in styrene copolymerization) led to Q = 1.64 and e = 0.98. The glass transition temperature T_g of poly(CyMA) was observed to be 91°C by thermomechanical analysis. Thermogravimetry of poly(CyMA) showed a 10% weight loss at 265°C in air.     

Characterization of a new qQq-FTICR mass spectrometer for post-translational modification analysis and top-down tandem mass spectrometry of whole proteins

The use of a new electrospray qQq Fourier transform ion cyclotron mass spectrometer (qQq-FTICR MS) instrument for biologic applications is described. This qQq-FTICR mass spectrometer was designed for the study of post-translationally modified proteins and for top-down analysis of biologically relevant protein samples. The utility of the instrument for the analysis of phosphorylation, a common and important post-translational modification, was investigated. Phosphorylation was chosen as an example because it is ubiquitous and challenging to analyze. In addition, the use of the instrument for top-down sequencing of proteins was explored since this instrument offers particular advantages to this approach. Top-down sequencing was performed on different proteins, including commercially available proteins and biologically derived samples such as the human E2 ubiquitin conjugating enzyme, UbCH10. A good sequence tag was obtained for the human UbCH10, allowing the unambiguous identification of the protein. The instrument was built with a commercially produced front end: a focusing rf-only quadrupole (Q0), followed by a resolving quadrupole (Q1), and a LINAC quadrupole collision cell (Q2), in combination with an FTICR mass analyzer. It has utility in the analysis of samples found in substoichiometric concentrations, as ions can be isolated in the mass resolving Q1 and accumulated in Q2 before analysis in the ICR cell. The speed and efficacy of the Q2 cooling and fragmentation was demonstrated on an LCMS-compatible time scale, and detection limits for phosphopeptides in the 10 amol/muL range (pM) were demonstrated. The instrument was designed to make several fragmentation methods available, including nozzle-skimmer fragmentation, Q2 collisionally activated dissociation (Q2 CAD), multipole storage assisted dissociation (MSAD), electron capture dissociation (ECD), infrared multiphoton induced dissociation (IRMPD), and sustained off resonance irradiation (SORI) CAD, thus allowing a variety of MS(n) experiments. A particularly useful aspect of the system was the use of Q1 to isolate ions from complex mixtures with narrow windows of isolation less than 1 m/z. These features enable top-down protein analysis experiments as well structural characterization of minor components of complex mixtures.     

High-performance liquid chromatographic analysis of a novel carbapenem antibiotic in human plasma and urine

High-performance liquid chromatographic methods for quantification of a novel carbapenem anti-infective agent, I, in plasma and urine have been developed, validated, and applied to clinical samples. The carbapenem is stabilized in the matrix by the addition of a non-nucleophilic buffer, rapid freezing, and storage at -70 degrees C. After addition of another carbapenem, II, as internal standard, plasma proteins are precipitated with acetonitrile, which is subsequently extracted from the sample with methylene chloride. A portion of the aqueous phase is injected onto a reversed-phase phenyl column that is eluted with 4% (v/v) acetonitrile in 15 mM ammonium phosphate (pH 7.4). The urine assay entails addition of the internal standard II to buffered urine, which is subsequently extracted with methylene chloride prior to injection of the aqueous phase onto a cation-exchange column. The urine assay mobile phase is 5% v/v tetrahydrofuran in 100 mM sodium acetate (pH 5.4). The detector response at 313 nm is a linear (r greater than 0.99) function of concentration over the ranges 0.50-100 micrograms/ml and 2.0-200 micrograms/ml for the plasma and urine assays, respectively. Thermal degradation products do not interfere with either assay. These assays have proven to be accurate, precise, reproducible, and rugged during clinical sample analyses.     

Radiation degradation of methyl α-chloroacrylate–methacrylonitrile copolymers

The radiation degradation behavior of methyl α-chloroacrylate (MCA) and methacrylonitrile (MCN) copolymers has been investigated as part of a program to develop high-sensitivity polymeric resists for integrated circuit manufacture. High-molecular-weight copolymers were prepared by emulsion techniques. Several different copolymer compositions were prepared varying from 19 to 68 mole % MCA. These copolymers were fractionated and then subjected to γ irradiation from a ⁶⁰Co Source. The G_s - G_s, G_s - 4G_s values were determined from M?;F>n_k^?1 and G_u^?1 versus dose plots, and the G_fs and G_s Values were then calculated. Molecular weights of both unirradiated and irradiated polymers were analyzed by membrane osmometry and gel permeation chromatography. All copolymers exhibited higher degradation susceptibilities than that of poly(methyl methacrylate) (PPMA), which has G_x = 1.3. The individual G_x and G_x values of the copolymers were found to fall between those of the two homopolymers, poly(methyl α-chloroacrylate) (G_x = 6.0) and polymethacrylonitrile (G_x ～ 3.1). The dependence of G_x and G_x values on molecular weight was minor. The crosslinking susceptibility of the poly(methyl α-chloroacrylate) (G_x ～ 0.8), was greatly decreased by copolymerization with MCN. Relatively small amounts of MCN caused a large drop in G_x, i.e., G_x ～ 0.15 at 32% MCN and G_x ～ 0.03 at 51% MCN. The observation could be attributed to the decreasing probability that crosslinking sites, in the MCA monomer units on adjacent chains, would lie in close proximity.     

Attrition patterns in a high ability programme for precollege students

Completion and performance data from 92 high ability seventh and eighth grade students in an eight‐week summer programme conducted in 1989 and sponsored by the GTE Service Corporation are examined.