Production and characterization of carbon-based adsorbents from waste lignocellulosic biomass: their effectiveness in heavy metal removal

Abstract

In this study, hazelnut shell and walnut shell which are the agricultural wastes existent abundantly in many countries were pyrolyzed at different temperatures in the temperature range of 400–700?°C in order to optimize the physicochemical properties of biochars. The biochars with large surface area were used to removal of lead (Pb²⁺) ions, one of the most important heavy metal pollutant, from aqueous solutions. The characterization of raw biomass and also biochars produced by pyrolysis were performed using FT-IR, BET, SEM, partial and elemental analysis techniques. In order to determine the adsorption characteristics of both biochars, batch adsorption experiments were carried out under different experimental conditions. The optimum conditions were determined by investigating the effect of adsorption parameters (initial heavy metal concentration, temperature, adsorbent amount, pH, contact time and mixing speed) for efficient removal of Pb²⁺ ions from aqueous solution. The experimental results were investigated in terms of Langmuir, Freundlich and Temkin isotherm models. Together with the calculated thermodynamic parameters, the adsorption mechanism was tried to be explained. In order to determine the kinetic model of the adsorption process, the experimental data were applied to pseudo first-order, pseudo second-order and intra-particle diffusion model, and the model constants were investigated.     

Effect of SC-41930, a potent selective leukotriene B4 receptor antagonist, in the guinea pig model of middle ear inflammation

Arachidonic acid metabolites such as prostaglandins and leukotrienes have been shown to play an important role in the pathogenesis of otitis media (OM). Among these mediators, leukotriene B4 (LTB4) is one of the most potent inducers of inflammatory processes. SC-41930 has been shown to be a specific LTB4 receptor antagonist both in vitro and in vivo. In this study, anti-inflammatory effects of SC-41930 were investigated in a guinea pig model of OM induced by middle ear (ME) inoculation of killed Staphylococcus aureus. Outcome of treatment was determined by measurement of myeloperoxidase activity in the samples of ME mucosa, evaluation of temporal bone histopathology, and presence of ME fluids. Myeloperoxidase activity in the SC-41930-treated group was found to be significantly lower than that in the control group. Histopathology of temporal bones indicated decreased inflammation in the treated group as compared to the controls. In addition, ME fluids were absent in four out of six treated animals. These results demonstrate that SC-41930 can produce significant anti-inflammatory effects in this model of OM.     

Novel TIGR/MYOC mutations in families with juvenile onset primary open angle glaucoma

Mutations in the trabecular meshwork induced glucocorticoid response protein (TIGR) or myocilin (MYOC) has recently been shown to cause juvenile onset primary open angle glaucoma (JOAG). In this study, we identified two new mutations (Asp380Ala and Ser502Pro) in two British families and another (Pro370Leu) in a French-Canadian family. These mutations were not present in a total of 106 normal chromosomes. In another Turkish family with JOAG, we also detected a sequence variant that was proven to be an amino acid polymorphism (Arg76Lys). No other sequence changes were found in the entire coding region and splice junctions of the TIGR/MYOC gene in this family. However, it is still possible that mutations either in the TIGR promoter or in another neighbouring gene could cause glaucoma in this JOAG family. Our results confirm the role of the TIGR/MYOC gene in the aetiology of the JOAG phenotype.     

Microstructural changes on high temperature treatment of a cold-worked and nitrided Fe–1%V alloy

An Fe–1.06%V alloy was used to study the control of recrystallization through fine VN precipitates in cold-worked and nitrided ferritic matrix. Nitriding was carried out at 475°C in ammonia atmosphere. Subsequent high temperature annealing process was performed in hydrogen gas for 795, 820, 860 and 880°C, respectively. The data on recrystallization indicates that kinetics of recrystallization obeys an Avrami type equation with a temperature independent time exponent. Transmission electron microscopy techniques were used to measure the precipitate sizes and to study the changes in the microstructure. The activation energy evaluated for recrystallization was found to be consistent with that governing the VN particle coarsening. From these findings it was concluded that the initiation of recrystallization is dominated by the interface reaction controlled growth of VN stringers at subgrain boundaries. After the disappearance of stringers, the interaction of fine precipitates with subgrain boundaries is minimized and hence recrystallization starts. © 1998 Chapman & Hall     

Response surface-based robust parameter design optimization with both qualitative and quantitative variables

The response surface-based robust parameter design, with its extensive use of optimization techniques and statistical tools, is known as an effective engineering design methodology for improving production processes, when input variables are quantitative on a continuous scale. In many engineering settings, however, there are situations where both qualitative and quantitative variables are considered. In such situations, traditional response surface designs may not be effective. To rectify this problem, this article lays out a foundation by embedding those input variables into a factorial design with pseudo-centre points. A 0–1 mixed-integer nonlinear programming model is then developed and the solutions found using three optimization tools, namely the outer approximation method, the branch-and-bound technique and the hybrid branch-and-cut algorithm, are compared with traditional counterparts. The numerical example shows that the proposed models result in better robust parameter design solutions than the traditional models.     

Some Tauberian theorems for regularly generated sequences

In this paper, we establish some Tauberian theorems for the Abel summability method in terms of regularly generated sequences which generalizes some results obtained in Çanak and Totur [?. Çanak, Ü. Totur, A note on Tauberian theorems for regularly generated sequences, Tamkang J. Math. 39 (2) (2008) 187-191].     

Freeze-Drying of Pharmaceutical Products: Research and Development Needs

Significance of pharmaceutical formulation (choosing of correct excipients in optimal quantities), effects of glass transition temperature, importance of theoretical modeling of the process, benefits of optimal control, and the advantages of remote monitoring of the process are presented. Experimental and theoretical research and development needs for the freeze-drying of pharmaceutical products are proposed and discussed.     

Mechanical characterization of highly porous β-Si3N4 ceramics fabricated via partial sintering & starch addition

In this study, porous β-Si₃N₄ ceramics containing limited amount of Sm₂O₃ and CaO as sintering aids were produced by addition of potato starch (10 and 20 vol.%) and partial sintering. Two different Si₃N₄ powders, α- and β-, were used as starting materials. Scanning electron microscopy investigations revealed that development of elongated β-Si₃N₄ grains were much more pronounced when α-Si₃N₄ starting powder was used. Even though porosity values of the compositions prepared by using α-Si₃N₄ (～57.0–58.4%) is significantly higher than the samples produced by β-Si₃N₄ (42.6%), no significant change was observed for the bending strength, fracture toughness and Weibull modulus. This indicates that microstructural features have a significant contribution to the mechanical properties of the porous materials in terms of bending strength and fracture toughness.     

A new processable donor–acceptor polymer displaying neutral state yellow electrochromism

We report here the synthesis of a new solution processable neutral state yellow polymeric electrochromic material containing 2,5-bis-dithienyl-1H-pyrrole (SNS)-donor and 1,8 naphthalimide-acceptor (SNS–NI) as a subunit. The electrochemical and optical properties were investigated via cyclic voltammetry (CV), UV–Vis absorption and fluorescence emission measurements, respectively. Besides, electrochromic performance of poly(SNS–NI) has been compared to the both the film preparation method and poly(1-phenyl-2,5-dithiophen-2-ylpyrrole) [poly(SNS–P)] as a standard polymer. In the poly(SNS–NI), yellow color of the polymer film at neutral state converted to green and then dark blue upon the polymer film fully oxidized in the positive regime. SNS–NI polymer film prepared via spin casting process exhibits a high contrast ratio in the near-IR region (ΔT% = 56% at 890 nm), a response time of about 1 s, high coloration efficiency (299 cm² C⁻¹) and retained its performance by 98.6% even after 5000 cycles. Finally, the results clearly indicate that both electronic nature of the molecule and film preparation method have a major impact on electrochromic performance of these polymers.     

Incremental discovery of new defects: application to screwing process monitoring

Defect detection by in-process monitoring plays a key role in the traceability and optimization of production. Many fault detection algorithms are trained on known faults. However, industrial data is generally unlabeled and certain faults are unknown or missing in the training dataset. This paper presents an original approach for the incremental discovery of new manufacturing defects, by Bayes rule and distance rejection. Rejects are analyzed periodically to determine the possible appearance of new defect cluster among them. Visualization then supports the cluster interpretation by a manufacturing expert. The approach was successfully applied to a screwing database from automotive industry.