Properties Of P1 Research Articles

Thermally versatile maleimide-based polymeric thin film for detection and separation of picric acid from polluted areas

2,4,6-Trinitrophenol, commonly known as picric acid, is a powerful explosive that has been used historically in military ammunition. Picric acid is extremely toxic and sensitive to friction and heat; thus, it is prone to accidental detonation at high temperatures. It is critical to detect and separate picric acid from the impacted areas. In the present study, we designed and developed a fluorescent copolymer (P1) for temperature-dependent picric acid detection. The solvatochromic and aggregation-induced emission (AIE) properties of P1 were utilized to detect picric acid at a high temperature of 40 °C (high alert level) by turn-off emission. Additionally, a polymeric thin film (F1) was fabricated by immobilizing P1 onto the surface of quartz slide. Notably, F1 retained its emissive properties across a range of temperatures (both relatively low and high alert levels), facilitated by its AIE characteristics. The portable film, F1, displayed a nanomolar sensitivity toward picric acid, making it suitable for on-site detection in aqueous media (neutral pH). Furthermore, F1 demonstrated efficient separation of picric acid from nitroaromatic explosive mixtures with a separation efficiency of 70 % over four cycles. Importantly, F1 exhibited practical utility in detecting and separating picric acid in real samples, highlighting its potential for environmental monitoring applications.

Investigating the effects of material properties on the mixing dynamics of cohesive particles in a twin screw mixer using a discrete element method approach

A discrete element method (DEM) model was developed for a co-rotating twin-screw mixer (TSM) consisting of conveying and kneading elements. This model was used to simulate the mixing of a cohesive binary system of particles (P1 and P2). The particles were calibrated using angle of repose and dynamic yield strength simulations. Properties of P1 were kept constant throughout the study while properties of P2 were varied. The TSM model was used to study the influence of particle size, density, and flowability of P2 on process outputs such as powder holdup, mean residence time (MRT), and degree of mixing along the length of the TSM. All the three particle properties were varied at three-factor levels with flowability ranging from good flow (GF), poor flow (PF), and very very poor flow (VVPF) based on Carr’s classification. The model provides fundamental insights into the differences in mixing in the conveying sections of the mixer for materials with different flowability. Due to the co-rotating nature of the screws, the majority of the material in the conveying sections was carried on one side of the TSM for GF and PF particles, while both the screws carried VVPF particles. The total steady-state holdup and the mean residence time (MRT) of particles inside the TSM were heavily influenced by particle flowability compared to the other two tested particle parameters. The holdup in the conveying compartments ranged from 11%–15% of the total holdup, while the kneading compartment comprised 40% of the total holdup in the mixer. The simulations found that VVPF particles mixed the fastest and that the GF particles had the highest tendency to demix. The model was also used to suggest and test other screw design configurations to improve mixing. A screw design with kneading elements closer to the mixer outlet resulted in better mixing of GF particles. A screw design consisting only of conveying elements achieved the same degree of mixing as the original screw design for VVPF particles. • A model for a co-rotating twin-screw mixer was developed using DEM. • Holdup and mean residence time was influenced by the particle flowability. • Particles were transported mainly on one of the conveying screws. • The model was also used to suggest changes to screw design configurations.

The coefficients of the HOMFLY polynomials of links

We study the expressions of p1−c(L)(l), the coefficient of the lowest power of m of the HOMFLY polynomial of a link L with c(L) components, give what these coefficients are if they include exactly two terms for knots and the properties of p1−c(L)(1) for knots as well as properties of higher derivatives of p1−c(L) evaluate at i. We show that there are infinitely many different links (knots), especially infinitely many different pretzel links (knots) to have such coefficients and infinitely many different pretzel links (knots) to have same p1−c(L)(l).

Effects of Pr-deficiency on thermal expansion and electrochemical properties in Pr1−xBaCo2O5+δ cathodes for IT-SOFCs

Pr-deficient Pr1−xBaCo2O5+δ (P1−xBCO) oxides are evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Effects of Pr-deficiency on electrical conductivity, thermal expansion and electrochemical properties are investigated. Both the conductivity and thermal expansion coefficient (TEC) decrease with increasing Pr-deficiency. All of the conductivity, thermal expansion and TGA measurements demonstrate the existence of high temperature order-disorder transition. The oxygen reduction mechanism for P1−xBCO cathodes are characterized by electrochemical impedance spectroscopy. Over the temperature range of 600−800°C, the cathode polarization resistance is mainly contributed from electronic charge transfer over the cathode surface. Proper Pr-deficiency reduces cathode polarization resistance (Rp), and the lowest Rp (0.081Ω cm2 at 700°C) is obtained for the P0.92BCO cathode. In addition, the effects of order-disorder transition on the properties of P1−xBCO cathodes have also been discussed. Maximum power densities of a single-cell with P0.92BCO cathode on 300-μm thick Sm0.2Ce0.8O1.9 (SDC) electrolyte achieve 446–987mWcm−2 at 650–800°C. These results suggest that, among various P1−xBCO oxides, P0.92BCO is the most promising candidate cathode material for IT-SOFCs.

Multiresponsive Photo-, Solvato-, Acido-, and Ionochromic Schiff Base Probe

Nonclassical protomeric tautomerism in Schiff bases have the advantage of controlling and differentiating specific interactions in the −C═N– linkage since its interactions are not governed by keto–enol tautomerism. Here, we report about the optical properties of a Schiff base probe (P1). X-ray structure analysis evidenced the existence of an intramolecular hydrogen bond which is responsible of a photochromic-fluorescent behavior. The properties of P1 were investigated by UV–vis and fluorescence spectroscopy in solution and solid state. A positive solvatochromism resulting from specific interactions taking place in P1 was studied by three different solvent scales, namely Lippert–Mataga, Kamlet–Taft, and Catalan, finding consistent results. Moreover, a strong acidochromic behavior was detected and the pKa and pKa* values were determined, finding a photobasic character. Further, an ionochromic behavior was stablished. P1 exhibits a λ-ratiometric fluorescence response toward Sn(IV) giving a luminescence color...

A comparative study of polymers containing naphthodifuranone and benzodifuranone units in the main chain

The synthesis of two new polymers containing the naphtho[2,1-b:3,4-b′]difuran-2,9-dione (1,10-NDF) or the ortho-benzo[1,2-b:6,5-b′]difuran-2,7-dione (1,8-BDF) chromophore in the main chain is described. The polymers P1 and P2′ were prepared upon Suzuki coupling of either 3-(4-bromophenyl)-8-(3-bromo-4,5-dimethoxyphenyl)-naphtho[2,1-b:3,4-b′]difuran-2,9-dione (M1) or 3,6-bis(4-bromophenyl)-1,2,3,5,6,7-hexahydrobenzo[1,2-b:6,5-b′]difuran-2,7-dione (M2′) and 2,2-(9,9-dioctyl-9H-fluorene-2,7-diyl-)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (M3), respectively. P2′ was subsequently converted into the oxidized form P2 upon reaction with nitrobenzene. Optical and electrochemical properties of P1 and P2 are described and compared with the properties of previously prepared polymer P3, which was synthesized upon Suzuki coupling of symmetrical 3,8-bis(4-bromophenyl)naphtho[2,1-b:3,4-b′]difuran-2,9-dione (M4) and M3. While the NDF-based polymers P1 and P3 exhibit absorption maxima around 480 nm, the BDF-based polymer P2 shows a maximum at 555 nm. Quantum chemical studies by the density functional theory method show that the BDF-based polymer is more planar than the polymers based on NDF. The excitation of the polymers causes a strong electron transfer from the backbone to the NDF/BDF core units. 1,10-NDF-based polymers exhibit excellent photostability in UV-light, while the 1,8-BDF-based polymer is less stable, if irradiated with a 200 W Hg lamp. All polymers exhibit low band gaps of 1.31 to 1.66 eV.

Alternating copolymers of 2,6-bis(p-dihexylaminostyryl)anthracene-9,10-diyl and N-octylcarbazole with large two-photon cross sections

We report the synthesis, thermal, one- and two-photon properties of poly(2,6-bis(p-dihexylaminostyryl)anthracene-9,10-diyl-alt-N-octylcarbazole-3,6-/2,7-diyl) (P1/P2). The as-synthesized polymers exhibit number-average molecular weights of 1.7 × 104 for P1 and 2.1 × 104 g/mol for P2. They emit strong one- and two-photon excitation fluorescence with the peak around 502 nm, and the fluorescence quantum yields around 0.76 in chloroform. In film state, P1 and P2 show different red-shift emission with the peaks at 512 nm and 523 nm, respectively. The DSC measurement reveals that as-synthesized polymers are all amorphous aggregates with the glass transition temperatures of 131 °C for P1 and 152 °C for P2. The solution two-photon absorption (TPA) properties of P1 and P2 in chloroform are measured by the two-photon-induced fluorescence method using femtosecond laser pulses (120 fs). The TPA cross sections (δ) are measured over the range of 700–900 nm. The maximal δ of P1 and P2 all appear at ∼800 nm and are 1010 GM and 940 GM per repeating unit, respectively. This suggests that no notable interactions among structure units that impair their fluorescence and TPA properties, and the polymers with large δ can be obtained by using the high TPA-active units as building blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Properties of cortical somatosensory evoked potentials in the awake rabbit.

By appropriate experimental procedures it was possible to distinguish the components of the contra- and ipsilateral cerebral somatosensory potentials evoked by electrical stimulation of an extremity in the unrestrained rabbit. The components of the contralateral response occur in the following order; an early positive primary wave (P1), a positive associative wave (P2), and ultimately a late negative N wave. The components of the ipsilateral response occur in the following order; a small positive wave P, the latency of which is intermediate between those of the contralateral P1 and P2 waves, and a large negative wave N, similar to the contralateral N wave. The different topographical distributions of these waves were elucidated by the use of insulated, chronically implanted electrodes glued onto the cortical surface. The properties of the waveform components were studied by various methods such as varying the stimulation parameters, simultaneous application of somesthetic and acoustic stimuli, and administration of narcotic drugs. The properties of P1 were similar to those of P28 in humans; the properties of P2 can be compared to those of P45; and, finally, the N wave resembles the late negative components observed in humans. Inconstant small positive waves of shorter latencies, which will be discussed in a following paper, may also be seen. Interestingly enough, no early negative wave such as that observed in humans (N20) was ever found. If, as is presently thought, this wave is, in fact, due to the folding of the cortical surface (Broughton, 1969), its absence is to be expected in the rabbit because the cortical surface of this species is lissencephalic and thus devoid of gyri.