Treatment of Oily Wastewater by Using Porous PVA Hydrogels as Oil Adsorbent

The adsorption of crude oil from wastewater on the crosslinked poly(vinyl alcohol) hydrogel (HPVA) and its foam (HPVAF) was reported. The macroporous HPVAF was prepared by adding CaCO₃ and epichlorohydrin as pore-forming agent and crosslinker, respectively. The prepared hydrogels were characterized, and their ability to adsorb and immobilize the crude oil was assessed by gravimetric method at the optimum condition. The HPVAF carrier demonstrated the improvement in the hydrocarbon trapping than the HPVA one. Scanning electron microscopy showed the presence of extracellular structures that could play an important role in the immobilization stability of crude oil on polymers. As well, the percentage removal ability of the crude oil by HPVAF was approximately, 82%. The results suggest the potential of using HPVA and HPVAF films as trapping for crude oil to enhance the treatment of oily wastewater with a low cost in an open marine environment.     

Spectrophotometric study on the charge transfer reaction between 2-amino-4-methylpyridine with chloranilic acid in polar solvents

Charge transfer (CT) complexes formed between 2-amino-4-methylpyridine as electron donor, chloranilic acid as electron acceptor was investigated spectrophotometrically in acetonitrile (AN), methanol (MeOH) and binary mixture of acetonitrile 50% + methanol 50% (MeOH-AN). Minimum–maximum absorbance method has been used for estimating the formation constants of the CT reactions (K_CT). Job’s method of continuous variation and photometric titration studies were used to detect the stoichiometric ratios of the formed complexes, and they showed that 1:1 complexes were produced. The molar extinction coefficient (e), oscillator strength (f), dipole moment (l), CT energy (E_CT), ionisation potential (I_P) and the dissociation energy (W) of the formed complexes were estimated; they reached acceptable values suggesting the stability of the formed CT complexes. The solid CT complexes were synthesised and characterised by elemental analyses, ¹H NMR and FTIR spectroscopies where the formed complexes included proton and electron transfer.     

Powder study of propanthioamide dervative C8H6N2S2

The crystal structure of 2‐cyano‐3‐(2‐thienyl)prop‐2‐enethioamide (C₈H₆N₂S₂), a propanethioamide derivative was solved from high resolution laboratory X‐ray powder diffraction data collected at ambient conditions. Structure determination was performed by means of the global optimization method of simulated annealing at a resolution of 1.5 Å. Rietveld refinement yielded an R_WP value of 4.02% (P2₁/a, a = 15.8174(2) Å, b = 5.6502(1) Å, c = 11.0952(1) Å, β = 116.9923(7)°, V = 883.6(5) ų, Z = 4). The molecules are stacked in parallel layers and are stabilized by hydrogen bonds. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Longitudinal mode competition in semiconductor lasers under optical feedback: Regime of short-external cavity

This paper introduces a theoretical study of longitudinal mode competition in semiconductor lasers subject to optical feedback. The study is based on a model of time-delay multimode rate equations taking into account both symmetric and asymmetric suppressions of modal gain. The model is numerically solved and applied to the case of a short-external cavity. Mode competition is characterized along the feedback-induced period-doubling route to chaos as well as under chaotic dynamics. Contributions of symmetric and asymmetric gain suppressions to both mode dynamics and modal operation under OFB are clarified. The results show that under chaotic dynamics, mode competition induces multimode hopping giving rise to asymmetric multimode output spectra. In regimes of continuous-wave operation, mode competition supports single-mode oscillation, and the side-mode suppression ratio improves with the increase of feedback. In the regime of strong feedback, the lasing mode moves to either long- or short-wavelength side in a seemingly random fashion, which is strongly related to asymmetric gain suppression.     

A novel synthesis of 2-arylhydrazono-6-amino-4-arylbenzene-1,3-dicarbonitriles and their conversion into phthalazines

Compounds 1a-d react with benzylidenemalononitrile 2 to yield dihydroaminopyridazines 3a-d and, in contrast, compounds 1e,f react with 2 under the same conditions to yield aminobenzenedicarbonitriles 8e,f compound 8e underwent intramolecular cyclization to phthalazine 9e. Compound 10e reacted with 2a to yield 11e.     

Synthesis,Antiviral, and Antimicrobial Activity of N‐ and S‐Alkylated Phthalazine Derivatives

A series of N‐alkylphthalazinone were synthesized by the reaction of phthalazin‐1(2H)‐one derivatives 1a , 1b , 1c with alkylating agents namely, propargyl, allyl bromide, epichlorohydrin, 1,3‐dichloro‐2‐propanol, 4‐bromobutylacetate, and 1‐(bromomethoxy)ethyl acetate to give the corresponding N‐alkylphthalazinone 2a , 2b , 2c , 3a , 3b , 3c , 5a , 5b , 5c , 6a , 6b , 6c , 7a , 7b , 7c , and 9a , 9b , 9c . Alkylation of phthalazin‐1(2H)‐thione to give a series from S‐alkylphthalazine 12 , 13 , 14 and thioglycosides 15 and 17 was performed. Deprotection of compounds 7a , 7b , 7c , 9a , 9b , 9c , 15 , and 17 resulted in the formation of the corresponding products 8a , 8b , 8c , 10a , 10b , 10c , 16 , and 18 . The structure of newly synthesized compounds was assigned by IR, ¹H, ¹³C NMR, and elemental analysis. Some of these compounds were screened for antiviral and antimicrobial activity.     

New trend for optical signal-to-noise ratio of disturbed Raman fiber amplifier

In a distributed Raman fiber amplifier (DRFA), Raman amplification allows a lower signal launch powers to transverse the span above the noise floor while still increasing the optical signal-to-noise ratio (OSNR). It improves the noise figure and reduces the nonlinear penalty of fiber systems. In this paper, we demonstrate a new trend of OSNR at different pump configurations: forward, backward and bidirectional pumping for DRFAs as a function of fiber length. We also present the variation of OSNR with both input pump power and input signal power. It is found that forward pumping provides the highest OSNR, reaching its maximum value of 37 dB. However, backward pumping provides the smallest OSNR that has its maximum of 22 dB and the bidirectional pumping provides the moderate OSNR between the others having its peak of 26 dB.     

Analysis and design of an electro-optic 2\times 2 switch using Ti: \hbox {KNbO}_3 as a waveguide based on MZI at 1.3\,\upmu \hbox {m}

This work describes an approach to design a $2\times 2$ optoelectronic switch based on the Mach–Zehnder interferometer with a channel profile of Titanium (Ti) diffused in Potassium niobate ( $\hbox {KNbO}_{3}$ ) at a wavelength of $1.3\,\upmu \hbox {m}$ . The evaluation parameters used are the insertion loss and the extinction ratio. The originality of this work is introducing the $\hbox {KNbO}_{3 }$ crystal as a host while optimizing the Ti strip thickness to provide a remarkable switching performance. Optimization leads to a lower switching voltage of 4 V, an insertion loss of 0.0261 dB and extinction ratio of 29.4 dB. The designed switch has a high switching capability and degree of reliability.     

The antimony(III)-bridged heteropolyanion sandwich dimers [Sb(II3(A-α-XW9O34)2]11- (X = SiIV, GeIV and C-shaped double-sandwich [SbIII6O2(PW6O26)(A-α-PW9O34)2]15-

Interaction of potassium antimony(iii) tartrate hydrate K(2)(SbC(4)H(2)O(6))(2)·3H(2)O with the trilacunary Keggin derivatives [A-α-XW(9)O(34)](10-) (X = Si(IV), Ge(IV)) and [A-α-PW(9)O(34)](9-) in aqueous acidic medium (pH 4.8) resulted in three novel polyanions, [Sb(3)(A-α-XW(9)O(34))(2)](11-) (X = Si(IV) (1), Ge(IV) (2)) and [Sb(6)O(2)(A-PW(6)O(26))(A-α-PW(9)O(34))(2)](15-) (3), which were isolated as the hydrated potassium salts K(11)[Sb(3)(A-α-XW(9)O(34))(2)]·31H(2)O (X = Si(IV) (K-1), Ge(IV) (K-2)) and the mixed potassium-sodium salt K(14)Na[Sb(6)O(2)(A-PW(6)O(26))(A-α-PW(9)O(34))(2)]·61H(2)O (KNa-3) salts, respectively, and characterized by single-crystal X-ray diffraction, IR spectroscopy, as well as elemental and thermogravimetric analyses. The Sb(III)-containing polyanions 1-3 possess unique structural features, as they represent the first examples of sandwich-type POMs with trigonal-pyramidal Sb(III)O(3) linkers. The stability of 1-3 in aqueous media was investigated by multinuclear ((183)W, (31)P) NMR and UV-Vis spectroscopy.