Chitosan is a well-known sorbent and effective in the uptake of anionic or reactive dyes, but it has deficiency in adsorption of basic dyes. In this work, chitosan/Fe-substituted hydroxyapatite composite beads were prepared in a different ratio via embedding of hydroxyapatite into chitosan solution for removal of basic dye and heavy metal from aqueous solution. The composite beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy in order to reveal their composition and surface morphology. In this particular study, methylene blue (MB) and lead (Pb (II)) ions were selected as representatives of dye and a heavy metal, respectively. The various experimental conditions affecting dye adsorption were explored to achieve maximum adsorption capacity. Moreover, the kinetic, thermodynamic and adsorption isotherm models were employed for the description of the heavy metal and dye adsorption processes. The results indicated that the prepared hydrogel is an efficient adsorbent for the aforementioned dye and metal concomitant with the ability of regeneration without losing the original activity and stability for water treatment applications.

Core physics courses are prescribed in engineering curricula by professional and accrediting bodies. However, factors such as curriculum crowding and time constraints frequently bring into question the content and the extent of coverage of these courses. A survey was undertaken to assess the attitudes of engineering faculty to physics, mathematics and chemistry courses. The results for physics confirm that, while many of the classical topics in physics are perceived as relevant in engineering curricula by all faculty, topics in modern physics are not. Furthermore, variations in attitudes towards modern physics exist on a departmental and regional basis. This paper presents the results of the physics survey, with an analysis of attitudes towards physics in general in engineering curricula and to individual topics in particular, and tries to suggest reasons for the variations in departmental and regional attitudes.

– We have developed an online questionnaire to find out the attitudes of engineering faculty to the content of physical science courses in the early stages of engineering curricula. The questionnaire was sent to 6985 engineering faculty at 101 universities in 27 countries. In this paper, we report the results obtained in relation to topics covered in core physics, chemistry, and mathematics courses in the freshmen and sophomore years. We found that, classical topics in physics and mathematics were well accepted by almost all faculty while the acceptance of topics in modern physics and chemistry showed variations based on the engineering discipline and geographic location of the respondents. Index Terms – physical sciences, curriculum, faculty attitudes.

Core physics courses are prescribed in engineering curricula by professional and accrediting bodies. However, factors such as curriculum crowding and time constraints frequently bring into question the content and the extent of coverage of these courses. A survey was undertaken to assess the attitudes of engineering faculty to physics, mathematics and chemistry courses. The results for physics confirm that, while many of the classical topics in physics are perceived as relevant in engineering curricula by all faculty, topics in modern physics are not. Furthermore, variations in attitudes towards modern physics exist on a departmental and regional basis. This paper presents the results of the physics survey, with an analysis of attitudes towards physics in general in engineering curricula and to individual topics in particular, and tries to suggest reasons for the variations in departmental and regional attitudes.

A crosslinked polymer hybrid film, ipn-poly(vinyl cinnamate-graft-2-hydroxy ethyl methacrylate)-v-poly(ethylene glycol dimethacrylate) was synthesized by UV initiation using poly(vinyl cinnamate) (polyVCi), 2-hydroxy ethyl methacrylate (HEMA) monomer and ethylene glycol dimethacrylate (EGDMA) crosslinker. Benzophenone (Ph 2 CO), was used as the photoinitiator. The synthesis was optimized by changing the concentration of HEMA, Ph 2 CO, EGDMA, and UV irradiation time. PolyVCi undergoes photocrosslinking by 2 + 2 photocylo addition while the monomer/crosslinker couple, HEMA/ EGDMA, undergoes free radical polymerization and crosslinking to form EGDMA crosslinked polyHEMA. Hence, simultaneous interpenetrating polymer network (IPN) formation occurs. The IPN consists of dual network of photocrosslinked polyVCi and EGDMA crosslinked polyHEMA chains. Grafting of HEMA/EGDMA chains on the polyVCi backbone also occur during network formation. The chemical functionalities present in the polyVCi/polyHEMA/polyEGDMA IPN films obtained were characterized by FTIR and SEM analysis. The contact angle measurements show enhanced wettability of the IPN film compared to polyVCi surface. TGA analysis confirms thermal stability of the films. Swelling behavior of the films examined in water and in ethanol reveals the effects of the chemical natures of polyVCi and polyHEMA as well as that of crosslinking on the hydrophilicity of the film. The films were tested as drug release matrices using flurbiprofen. The drug was loaded into the film matrix during IPN formation under UV irradiation. PolyVCi/polyHEMA/polyEGDMA IPN proved to be a suitable release matrix for flurbiprofen demonstrating controlled release behavior and zero-order release kinetics. The release mechanism was confirmed by its Ritger-Peppas "n" value (1.00 to 1.42), which indicates super case II release.

A crosslinked polymer hybrid film, ipn-poly(vinyl cinnamate-graft-2-hydroxy ethyl methacrylate)-v-poly(ethylene glycol dimethacrylate) was synthesized by UV initiation using poly(vinyl cinnamate) (polyVCi), 2-hydroxy ethyl methacrylate (HEMA) monomer and ethylene glycol dimethacrylate (EGDMA) crosslinker. Benzophenone (Ph 2 CO), was used as the photoinitiator. The synthesis was optimized by changing the concentration of HEMA, Ph 2 CO, EGDMA, and UV irradiation time. PolyVCi undergoes photocrosslinking by 2 + 2 photocylo addition while the monomer/crosslinker couple, HEMA/ EGDMA, undergoes free radical polymerization and crosslinking to form EGDMA crosslinked polyHEMA. Hence, simultaneous interpenetrating polymer network (IPN) formation occurs. The IPN consists of dual network of photocrosslinked polyVCi and EGDMA crosslinked polyHEMA chains. Grafting of HEMA/EGDMA chains on the polyVCi backbone also occur during network formation. The chemical functionalities present in the polyVCi/polyHEMA/polyEGDMA IPN films obtained were characterized by FTIR and SEM analysis. The contact angle measurements show enhanced wettability of the IPN film compared to polyVCi surface. TGA analysis confirms thermal stability of the films. Swelling behavior of the films examined in water and in ethanol reveals the effects of the chemical natures of polyVCi and polyHEMA as well as that of crosslinking on the hydrophilicity of the film. The films were tested as drug release matrices using flurbiprofen. The drug was loaded into the film matrix during IPN formation under UV irradiation. PolyVCi/polyHEMA/polyEGDMA IPN proved to be a suitable release matrix for flurbiprofen demonstrating controlled release behavior and zero-order release kinetics. The release mechanism was confirmed by its Ritger-Peppas "n" value (1.00 to 1.42), which indicates super case II release.

Random copolymers of poly(ethylene glycol) methacrylate (PEGM), and diethyl amino ethyl methacrylate (DEAEM) were synthesized at low, and high conversions by photoinitiation. Crosslinked poly(PEGM-co-DEAEM) samples were obtained, and characterized by FTIR, SEM, DSC, TGA, and elemental analyses. Swelling behavior of the copolymers revealed that the copolymers acted as superabsorbent hydrogels. The monomer reactivity ratios were calculated using Fineman Ross, Extended Kelen Tüdøs, and Mayo Lewis methods that gave r 1 (PEGM) = 0.90, r 2 (DEAEM) = 0.14 at low conversions. At high conversions r 1 and r 2 values were calculated as 1.01 and 0.40, respectively. Adsorption isotherms of methyl orange (MO) onto hydrogels were studied using Langmuir, Freundlich, and Temkin models. The experimental data fitted well with the Langmuir equation. The maximum adsorption capacity for MO was 212.7 mg g −1 at pH = 3. The adsorption data gave best fit with the pseudo-second order kinetic model. Thermodynamic evaluation showed spontaneous nature for MO adsorption onto poly(PEGM-co-DEAEM) hydrogels.

The grafting of poly(4-vinylpyridine) (P4VP) on to chitosan by ceric ion initiation was studied under homogeneous conditions in 1% acetic acid solution. The products were characterized by infrared (IR) spectrometry and differential scanning calorimetry (DSC). The effects of monomer concentration and temperature on per cent grafting were studied. Per cent grafting was observed to increase with the amount of monomer, showing a tendency to level off at a 4VP concentration of 0.53 mol/l. Per cent grafting increased with temperature up to 70°C and then decreased to 80°C. Solubility tests carried out on grafted chitosan samples revealed that the samples swelled in 1:1 and 1:2 acetic acid:ethanol solvent mixtures.

The potential of different forms of chitosan to adsorb iron(III) ion from a Jectofer [an iron(III)–sorbitol–citric acid complex] solution was investigated. The working solution was chosen as Jectofer, to mimic the composition of excess iron(III) as may be found in biological systems. The equilibrium studies showed that chitosan powder has the highest sorption capacity for the iron(III) ion when compared to chitosan flakes and microspheres. The amount of iron(III) adsorbed onto chitosan was found to increase with the contact time to reach equilibrium within 3 h at 37°C. A higher initial concentration of a Jectofer solution resulted in a higher amount of iron(III) adsorbed. Higher pH values, in the range 2–7, also resulted in an increase in iron(III) uptake from the solution. The data of adsorption from the Jectofer solution were found to correlate well with the Freundlich isotherm equation. In vitro adsorption experiments showed that chitosan is capable of adsorbing excess iron, measured in terms of the ferritin level, in human blood. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1185–1192, 2002; DOI 10.1002/app.10416

Grafting of poly(triethylene glycol dimethacrylate) (poly(TriEGDMA)), onto chitosan by ceric ion initiation has been investigated. The grafting conditions were optimized by studying the effect of monomer and initiator concentrations as well as time and temperature. Products with lower grafting yields (90–261%) were water and acid soluble. Those with higher grafting yields (350–868%) were insoluble, indicating a cross linked structure. Chitosan-graft- poly(TriEGDMA) products had a lower thermal stability than chitosan as revealed by DSC analysis. C-13 NMR and FTIR analyses suggested a grafting mechanism that proceeds via oxidation and chain scission of chitosan. The products are degraded by the enzymes lysozyme, lipase and α-amylase–protease.

Photoinitiated graft copolymerization of acrylamide onto chitosan under heterogeneous conditions and in the absence of a photo initiator was investigated. The effect of irradiation time, the amount of chitosan and monomer concentration on the extent of grafting was examined. The maximum grafting percentage obtained was 294%. The copolymer was characterized using carbon-13 nuclear magnetic resonance ( 13 C-NMR) spectroscopy, X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The system designed allows synthesis of grafted chitosan with free amine groups which are otherwise possible only by chemical protection. The swelling properties of copolymer were followed in aqueous solution.

n-Butyl isocyanate (nBIC) was polymerized in bulk by the Pruitt-Baggett adduct (PBA) at -23, 0.0, and 25.0"C. Polymerization was accompanied by trimerization to the cyclic isocyanurates at all temperatures. Spectroscopic evidences supported the nylon-1 structure for both trimer and polymer. The polymer/trimer ratio and the molecular weight of produced polymers were found to increase with decreasing temperature. The Pruitt-Baggett catalyst (PBC) , which is the reaction product of (PBA + HzO) system, also polymerized nBIC, but with a relatively slower rate. In aromatic and etheric solutions, nBIC was only trimerized by PBA. Copolymerization of nBIC with propylene oxide by PBA and PBC failed. Some selected monoisocyanates were also polymerized by PBA. 0 1993 John Wiley & Sons, Inc.

A novel, soluble, perylene oligomeric diimide dye, termed EOPPI was synthesized in high yield; for comparison, a small dye molecule, termed EOPDI, was also synthesized; both products readily dissolved in a wide range of organic solvents. The compounds were characterized using NMR, IR, MS, UV-vis, MS, GC-MS, HRMS, DSC, TGA, elemental analysis and cyclic voltammetry. The average molecular mass of EOPPI was 4460, its intrinsic viscosity was 0.3 dl g À1 in m-cresol at 20 C. The band gap energy (E g), LUMO and HOMO energy values were 2.25, À3.78 and À6.03 eV for the small dye molecule and 2.24, À3.85 and À6.09 eV for the oligomer, respectively. The temperatures at which the monomer and oligomer began to lose mass were 300 and 375 C, respectively. The oligomer showed concentrationdependent color tunability.

Exploration of optoelectronic properties of novel phosphorus-embedded π-conjugated compounds would provide us with fundamental information about the design of hitherto unknown electroactive organic materials. Herein, detailed photophysical and electrochemical profiles of a series of benzene-cored diketophosphanyl compounds were investigated with steady-and time-resolved spectroscopic and spectroelectrochemical techniques. The comparative studies revealed the impact of phosphorus and nitrogen atoms on their triplet energies and on the behaviour of electrochemical processes to form radical species. 1. Introduction The creation of novel main-group element-embedded π-conjugated organic compounds and their building blocks them is vitally important for the development of the next-generation electroactive materials for organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs) and organic field effect transistors (OFETs) [1-4]. Particularly, much attention has been paid to phosphorus-containing π-conjugated compounds, because their optoelectronic properties (e.g., HOMO/LUMO energies, photo-absorption/emission properties, etc.) can be effectively tailored through (C-P)σ*-π* electronic interaction and chemical P-functionalization [5-9]. Making use of their unique physicochemical properties, phosphorus-containing π-conjugated compounds have been utilized as high triplet-energy host materials for OLEDs [10,11] and as emitters [12] in the field of optoelectronics.

(Z)-4-(4-cyanophenylamino)-4-oxobut-2-enoic acid (LH) and its new triphenyltin (IV) derivative (Ph 3 SnL) were synthesized and further investigated for their binding with ds.DNA under physiological conditions {pH: 4.7 (stomach); 7.4 (blood), 37°C} using UV-Visible/fluorescence spectroscopy, cyclic voltammetry and viscosity measurement techniques. Spectral responses as well as experimental findings from all the techniques i.e., binding constant (K b), binding site size (n) and free energy change (DG) correlated with each other and indicated formation of spontaneous compound-DNA complexes via intercalation of compounds into the DNA base pairs. Values of kinetic parameter, K b , revealed comparatively greater binding of both the compounds with DNA at stomach pH (4.7). However among both compounds organotin complex (Ph 3 SnL) showed comparatively greater binding than that of its ligand (LH) as evident from its, K b , values at both the pH values. In general, K b values were evaluated greater for Ph 3 SnL at stomach pH {: K b : 8.65 • 10 4 M À1 (UV); 5.49 • 10 4 M À1 (fluorescence); 8.85 • 10 4 M À1 (CV)}. Voltammetric responses of both compounds before and after the addition of DNA indicated that diffusion controlled processes are involved. Complex Ph 3 SnL exhibited the best antitumor activity.

The synthesis of perylene-3,4,9,10-tetracarboxylic acid-bis(N,N-dodecylpolyimide) (poly PTDI) and polyamic acid has been achieved from perylene dianhydride and dodecylamine. It was found that this new polyimide has very high thermal photostability. Poly PTDI decomposes at 475ЊC and shows weak fluorescence compared with the monomer PTDI possibly due to aggregration in the polymer. Its solubility in some of the common organic solvents, acetonitrile, dimethyl formamide, etc., makes spectroscopic and photochemical studies and applications possible in the liquid phase. The emission characteristics are similar to mono PTDI. Poly PTDI, a luminescent electron acceptor polymer, is a new reliable probe for a photosensitizer at energy transfer and electron transfer photochemical reactions.