Standoff detection of high explosive materials at 50 meters in ambient light conditions using a small Raman instrument

We have designed and demonstrated a standoff Raman system for detecting high explosive materials at distances up to 50 meters in ambient light conditions. In the system, light is collected using an 8-in. Schmidt-Cassegrain telescope fiber-coupled to an f/1.8 spectrograph with a gated intensified charge-coupled device (ICCD) detector. A frequency-doubled Nd : YAG (532 nm) pulsed (10 Hz) laser is used as the excitation source for measuring remote spectra of samples containing up to 8% explosive materials. The explosives RDX, TNT, and PETN as well as nitrate- and chlorate-containing materials were used to evaluate the performance of the system with samples placed at distances of 27 and 50 meters. Laser power studies were performed to determine the effects of laser heating and photodegradation on the samples. Raman signal levels were found to increase linearly with increasing laser energy up to approximately 3 x 10(6) W/cm2 for all samples except TNT, which showed some evidence of photo- or thermal degradation at higher laser power densities. Detector gate width studies showed that Raman spectra could be acquired in high levels of ambient light using a 10 microsecond gate width.     

Time-derivative equations for fatigue crack growth in metals

Predicting fatigue crack growth in metals remains a difficult task because available models are based on cycle-derivative equations, such as the Paris law, while service loads are often far from being cyclic. The main objective of this paper is therefore to propose a set of time-derivative equations for fatigue crack growth. The model is based on the thermodynamics of dissipative processes. For this purpose, three global state variables are introduced in order to characterize the state of the crackthe crack length a, the plastic blunting at crack tip and the intensity of crack opening C. Thermodynamics counterparts are introduced for each variable. Special attention is paid to the elastic energy stored inside the crack tip plastic zone, because, in practice, residual stresses at crack tip are known to considerably influence fatigue crack growth. The stored energy is included in the energy balance equation, and this leads to the appearance of a kinematics hardening term in the yield criterion for the cracked structure. No dissipation is associated with crack opening, but to crack growth and to crack tip blunting. Finally, the model consists in two laws: a crack propagation law, which is a relationship between d dt and da/dt and which observes the inequality stemmed from the second principle, and an elastic-plastic constitutive behaviour for the cracked structure, which provides d dt versus applied-load. The model was implemented and tested. It reproduces successfully the main features of fatigue crack growth as reported in the literature, such as the Paris law, the stress-ratio effect and the overload retardation effect.     

Operation Babel: A survey of the effectiveness of the foreign language requirements for the PhD degree in psychology.

681 usable questionnaire returns were received from PhD psychologist respondents. Since completing the language requirements 65% or almost ? of the cases had not read a single item (article or book). "The median number of items read in French, German, Spanish, and Russian was 0." 70% made no oral use of the languages. There is an "extreme incongruity between input and output" in the study of foreign languages at the PhD level. Alternative solutions are proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectrophotometric Determination of the Thermodynamic pK Value of Picric Acid in Water at 25 °C

The thermodynamic pK value of picric acid was determined spectrophotometrically in water containing hydrochloric acid to repress the ionization. The pK value 0.33 (K ≈ 0.46) was obtained from data at 450 mμ. Attempts to determine the pK value by potentiometric titrations of picric acid and by spectrophotometric measurements of picric acid solutions in the near-saturation range did not yield satisfactory results. The new pK value is compared with previously published values.     

Polymerization of 2-allyl-1-methylenecyclohexane by the cyclic polymerization mechanism

2-Ally-1-methylenecyclohexane is a compound which is functionally capable of undergoing polymerization by the alternating intra-intermolecular propagation mechanism to produce poly[1,8-methylene[4.3.0] bicyclononane]. This monomer was synthesized and its polymerization through use of cationic and Ziegler-type initiators was studied. Synthesis of the monomer was accomplished by the following reaction sequence: (1) conversion of cyclohexanone to 2-allycyelohexanone by reaction wtih allyl bromide and sodium amide and (2) conversion of 2-allycyclohexanone to the desired monomer by reaction with the phosphorane derived from methyltriphenylphosphonium bromide. Polymerizaton was accomplished by use of boron trifluoride resulting in 44% conversion to polymer, of which 94% was soluble. Through use of infrared and nuclear magnetic resonance techniques, the soluble portion of the polymer was shown to contain 54% of bicyclic units and the remainder to be non-cyelized monomer units in which the residual unsaturation was composed predominantly of allyl groups.     

Thermodynamic Constants for Association of Isomeric Chlorobenzoic and Toluic Acids With 1,3-Diphenyl-guanidine in Benzene

This paper reports values of ΔF₂₅, ΔH, and ΔS₂₅ for the association of diphenylguanidine with the isomeric monochlorobenzoic acids and the isomeric toluic acids in benzene from spectrophotometric measurements at 25 and 30 °C, using bromophthalein magenta E (3′, 5′, 3″, 5″-tetrabromophenolphthalein ethyl ester) as the indicator. The results are compared with available data for other donor-acceptor associations in aprotic solvents which include the monomer-dimer equilibrium of benzoic acids, the association of tertiary amines with iodine, and the association of certain oxygen bases with phenols. The comparisons indicate that the value of the ratio ΔH/298ΔS is approximately constant in the following associations in aprotic solvents: (1) Association of phenolic or carboxylic acids with nitrogenous bases to form hydrogen bonded ion-pairs; (2) hydrogen bonding of weakly acidic phenols to nitrogenous bases; (3) association of tertiary amines with iodine. A somewhat smaller value for this ratio seems to apply to most associations of phenols with oxygen bases. Possible applications of these findings include estimation of other thermodynamic constants when one of the constants ΔF, ΔH, or ΔS is known, and clarification of the relative importance of ionic and covalent contributions in hydrogen bond formation.     

Recalibration of the NBS Glass Standards of Spectral Transmittance

In 1934, Gibson, Walker, and Brown developed sets of four colored glass filters to serve as working standards of spectral transmittance for checking the reliability of spectrophotometers. Several sets of these glasses were measured carefully and reserved and designated as future reference standards. Duplicate standards evaluated by comparison with the reference standards are available by purchase to the public. The current set of reference standards was established in the years 1945 to 1947, and one of these reference standards (selenium-red) was recalibrated in 1952. This paper reports a recalibration, made in 1961 and 1962, of all four glasses (selenium-red, carbon-yellow, copper-green, cobalt-blue) on three spectrophotometers (Cary 14, Beckman DU, König-Martens). Except for the cobalt-blue standard, the values of spectral transmittance found differ from those previously assigned by amounts differing at some wavelengths by as much as or slightly more than the uncertainties estimated for the present values, though not by amounts exceeding the combined uncertainties of the present and previous determinations. The indicated changes for these three standards are fairly regular, however, and support the view that the selenium-red and carbon-yellow standards are changing chiefly by formation of a reflectance-reducing film on the surfaces. The indicated rate of upward drift is slow, and suggests that it takes about 10 years for the drift to exceed the assigned uncertainity.     

The influence of irrelevant biographical information in teacher evaluation.

Investigated the importance of out-of-role Research in teacher evaluation. 60 administrators were presented 1 of 2 variations of a teacher's application form from which they assessed the personality traits of the teacher and indicated their interest in seeing the teacher for an interview. A multivariate analysis of variance revealed that altering responses for out-of-role behavior (positive vs negative) resulted in significantly lower trait ratings and less likelihood of an interview for the teacher with negative out-of-role behavior than for the teacher with positive out-of-role behavior (p     

Shared parenting agreements after marital separation: The roles of empathy and narcissism.

The identification of psychological and interpersonal factors that predict cooperation and agreement between ex-spouses is important to understanding, and eventually promoting, healthy postdivorce adjustment of parents and their children. By drawing on object relations theory, the authors identified differences between 16 ex-couples who were able to negotiate and maintain a cooperative parenting plan after separation ( "agreed ex-couples") and 16 ex-couples who disagree about parenting arrangements ("disagreed ex-couples") but were similar in age, educational background, age of their children, and time since separation. As expected, disagreed ex-couples were more narcissistic, more interpersonally vulnerable, less able to take another's perspective, less concerned about the feelings and needs of others, more self-oriented, and less child-oriented and more self-important in their parenting attitudes than agreed ex-couples. Our findings also supported a process mediational model of "child-centeredness" that attempts to elucidate the pathways through which these variables are interrelated… (PsycINFO Database Record (c) 2010 APA, all rights reserved)