Changing the Status Quo in Environmental Engineering Education in Response to Emerging Markets

The job market and skill needs have been expanding for environmental engineers requiring more interdisciplinary training and global citizenship. The 1970s was a decade of regulatory activities, the 1980s was a decade of major environmental disasters, the 1990s was a decade for global awakening, and the first decade of the 21st century is becoming the decade of concern for increasing global environmental stress. In parallel with the environmental trends, the environmental engineering programs have evolved from strictly water/wastewater focus to interdisciplinary programs with a wide selection of courses such as computer science, meteorology, aquatic biology, and ecology in addition to the classical environmental engineering curriculum. Advancements in science and technology, changing demographics, new delivery structures, changes in educational programs and policies, new regulatory requirements, increased global interactions, and recent large scale events with significant environmental impacts have increased the needs for engineers who are trained in environmental engineering discipline with adequate skills for addressing the emerging challenges. This technical note presents the emerging job markets and the corresponding skill needs for environmental engineers to respond to current and evolving environmental challenges both at regional and global scales.     

Schiff bases as corrosion inhibitor for aluminium in HCl solution

Three Schiff bases named 1,5-bis[2-(2-hydroxybenzylideneamino)phenoxy]-3-oxopentane (D1), 1,5-bis[2-(5-chloro-2-hydroxybenzylideneamino)phenoxy]-3-oxopentane (D2) and 1,5-bis[2-(5-bromo-2-hydroxybenzylideneamino)phenoxy]-3-oxopentane (D3) were synthesized and their inhibitive capabilities on the aluminium corrosion in 0.1 M HCl were investigated by means of electrochemical impedance spectroscopy, Tafel polarisation and scanning electron microscopy techniques. Results showed that, compounds under study exhibit inhibitor properties and adsorption of these compounds was found to accord with Temkin adsorption isotherm. Polarisation curves indicated that the studied Schiff bases were cathodic inhibitor and the effectiveness of these inhibitors decreased in the order of D3 > D2 > D1. Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies determined experimentally.     

Co-delivery of pemetrexed and miR-21 antisense oligonucleotide by lipid-polymer hybrid nanoparticles and effects on glioblastoma cells

Abstract

Combination therapy using anticancer drugs and nucleic acid is a more promising strategy to overcome multidrug resistance in cancer and to enhance apoptosis. In this study, lipid-polymer hybrid nanoparticles (LPNs), which contain both pemetrexed and miR-21 antisense oligonucleotide (anti-miR-21), have been developed for treatment of glioblastoma, the most aggressive type of brain tumor. Prepared LPNs have been well characterized by particle size distribution and zeta potential measurements, determination of encapsulation efficiency, and in vitro release experiments. Morphology of LPNs was determined by transmission electron microscopy. LPNs had a hydrodynamic size below 100?nm and exhibited sustained release of pemetrexed up to 10?h. Encapsulation of pemetrexed in LPNs increased cellular uptake from 6% to 78%. Results of confocal microscopy analysis have shown that co-delivery of anti-miR-21 significantly improved accumulation of LPNs in the nucleus of U87MG cells. Nevertheless, more effective cytotoxicity results could not be obtained due to low concentration of anti-miR-21, loaded in LPNs. We expect that the effective drug delivery systems can be obtained with higher concentration of anti-miR-21 for the treatment of glioblastoma.     

Poly(N-methyl aniline) thin films on copper: Synthesis, characterization and corrosion protection

Poly(N-methyl aniline) (PNMA) coatings were synthesized on copper by electrochemical polymerization of N-methyl aniline in aqueous oxalic acid solution by using cyclic voltammetry. The optimum electrodeposition conditions (e.g. upper potential limit, scan rate and cycle number) were determined in order to obtain PNMA coatings to have the best corrosion performance. PNMA coatings were characterized by cyclic voltammetry, Fourier Transform Infrared-Attenuated Total Reflectance spectroscopy and scanning electron microscopy. Redox parameters found after electrochemical tests indicate a thin film character and diffusion controlled electroactive behavior of PNMA. Corrosion test results revealed that PNMA coating appears to enhance protection of copper in 0.1 M H₂SO₄ solution.     

Pitch-based segmentation and recognition of dot-matrix text

Dot-matrix text recognition is a difficult problem, especially when characters are broken into several disconnected components. We present a dot-matrix text recognition system which uses the fact that dot-matrix fonts are fixed-pitch, in order to overcome the difficulty of the segmentation process. After finding the most likely pitch of the text, a decision is made as to whether the text is written in a fixed-pitch or proportional font. Fixed-pitch text is segmented using a pitch-based segmentation process that can successfully segment both touching and broken characters. We report performance results for the pitch estimation, fixed-pitch decision and segmentation, and recognition processes. Received October 18, 1999 / Revised April 21, 2000     

CFB combustion of low-grade lignites: Operating stability and emissions

This work presents the results of a comprehensive experimental investigation on the combustion of the low grade Turkish lignites in a 30 kW_th circulating fluidized bed combustor. This is the first study of this kind has ever been undertaken on these coals. Eighteen lignite samples procured from various lignite sites of Turkey have been burned under similar combustion conditions in order to access to their combustion stability and to determine the emissions of the major pollutants such as CO, NO_X and SO₂ in the flue gas from combustor. The qualities of lignites were evaluated based on van Krevelen graph which was highly scattered and diverse in respect to the degree of ageing. A steady and stable combustion was observed in the temperature range of 725–950 °C with an average operating temperature of around 850 ± 50 °C for all lignites. Under the operating condition applied in the study, CO, NO_X and SO₂ emissions varied mostly in the ranges of 120–600 mg/Nm³, 90–420 mg/Nm³ and 1100 mg/Nm³ - 18000 mg/Nm³, respectively. From the experimental results it seems that the most challenging problem may be faced during the CFB combustion of most of these lignites will be SO₂ emissions.     

On-line preconcentration of copper as its pyrocatechol violet complex on Chromosorb 105 for flame atomic absorption spectrometric determinations

An on-line solid phase extraction method for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS) has been described. It is based on the adsorption of copper(II) ion onto a home made mini column of Chromosorb 105 resin loaded with pyrocatechol violet at the pH range of 5.0-8.0, then eluted with 1 mol L(-1) HNO(3). Several parameters, such as pH of the sample solution, amount of Chromosorb 105 resin, volume of sample and eluent, type of eluent, flow rates of sample and eluent, governing the efficiency and throughput of the method were evaluated. The concentration of the copper ion detected after preconcentration was in agreement with the added amount. At optimized conditions, for 15 min of preconcentration time (30 mL of sample volume), the system achieved a detection limit of 0.02 microg L(-1), with relative standard deviation 1.1% at 0.03 microg mL(-1) copper. The present method was found to be applicable to the preconcentration of Cu(II) in natural water samples.     

Silver and proton driven fluorescent multiple-mode molecular logic gates employing phthalocyanines

Spectral properties and switch behavior of two alkyl thia units bearing Zn (II) phthalocyanine derivatives (Pc-A and Pc-B) were investigated in solvents and in solid matrix of ethyl cellulose by means of absorption and emission spectroscopy. Fluorescence lifetime and fluorescence quantum yield values of the Zn (II) phthalocyanines were calculated. The employed phthalocyanines demonstrated multiple molecular logic gate functions operated by H⁺ and Ag⁺ ions as chemical inputs. The silver driven fluorescence modulation of the Pc-A arises from reversible variations in emission signal intensity at 717 nm. The Pc-B exhibited a similar decreasing emission response to proton and silver ions and an accompanying increasing peak yielding an isobestic point at 746 nm upon protonation. The phthalocyanine doped thin films selectively responded to silver ions in sub-nano and/or pico molar levels. Observed detection limits were 7.6 × 10⁻¹² and 2.3 × 10⁻¹¹ M for Pc-A and Pc-B, respectively. In immobilized phases the attained reversible relative signal changes of Pc-A and Pc-B were 82 and 90%, respectively.