Nickel removal characteristics of an immobilized macro fungus: equilibrium,kinetic and mechanism analysis of the biosorption

BACKGROUND: An immobilized new biosorbent was prepared from macro fungi Lactarius salmonicolor for the effective removal of nickel ions from aqueous media. Operating conditions were optimized as functions of initial pH, agitation time, sorbent amount and dynamic flow rate. Immobilization and biosorption mechanism were examined and the developed biosorbent was tested for the removal of nickel ions from real wastewater. RESULTS: Biosorption performance of the biomass continuously increased in the pH range 2.0–8.0. The coverage of the biosorbent surface by silica gel resulted in a significant increase in biosorption yield of nickel ions. The highest nickel loading capacity was obtained as 114.44 mg g^?1 using a relatively small amount of immobilized biosorbent. Biosorption equilibrium time was recorded as 5 min. Experimental data were analyzed by different isotherm and kinetic models. Infrared spectroscopy, scanning electron microscopy and X‐ray energy dispersive analysis confirmed the process. The sorbent exhibited relatively good recovery potential in dynamic flow mode studies. Biosorption capacity of immobilized biosorbent was noted as 14.90 mg g^?1 in real wastewater. CONCLUSION: Silica gel immobilized biomass of L. salmonicolor is to be a low cost and potential biosorbent with high biosorption capacity for the removal of contaminating nickel from aqueous media. © 2012 Society of Chemical Industry     

Lactate detection by colorimetric measurement in real human sweat by microfluidic-based biosensor on flexible substrate

In this study, we describe the colorimetric detection of lactate concentration in real human sweat samples, as an indication of the performance of especially athletes, on a microfluidic device fabricated on a microfibrous nonwoven substrate comprising microfluidic channels and detection reservoirs. A narrow group (10 healthy individuals: 5 women and 5 men) within age range of 20–25 was used. The optimization and real sweat studies demonstrated that color formation on the biosensor surface is influenced not only by the enzyme, ABTS, gelatin ratios but also by many parameters such as storage conditions. Usage of real sweat samples showed that simulated samples only have limited similarity with the real samples and their contents can have a significant impact on the biosensor, in our case on color formation. To understand the response better, larger group of human subjects should be examined in detail in terms of effect of sweat properties to biosensor signal.     

Preparation and Use of Poly(hydroxyethyl methacrylate) Cryogels Containing L‐Histidine for β‐Casein Adsorption

The objective of this study was to determine β‐casein adsorption by using supermacroporous poly(2‐hydroxyethyl methacrylate‐N‐methacryloyl‐(l) ‐histidine methyl ester) [p(HEMA‐MAH)] cryogel. β‐Casein adsorption properties of p(HEMA‐MAH) cryogel were studied for the application of β‐casein purification. The cryogel was produced by free radical polymerization initiated by N,N,N’,N’‐tetramethylene diamine and ammonium persulfate pairs in an ice bath. P(HEMA‐MAH) cryogel was characterized by swelling tests, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the flow rate, pH, temperature, initial β‐casein concentration, and ionic strength on the adsorption efficiency of cryogel were studied. The equilibrium swelling degree of the p(HEMA‐MAH) cryogel was 6.73 g H₂O/g cryogel. β‐Casein adsorption capacity of p(HEMA‐MAH) cryogel from aqueous solution was estimated as 31.17 mg/g cryogel. It was also observed that β‐casein could be repeatedly adsorbed and desorbed with p(HEMA‐MAH) cryogel without significant loss in the adsorption capacity.     

Synthesis and thermal characterization of macromonomeric azo initiator containing poly(ε-caprolactone): Styrene and methyl methacrylate copolymerization

Macromonomeric azo initiator containing biodegradable poly(ε-caprolactone, (PCL) was synthesized by the condensation reaction of PCL with 4,4′-azobis(4-cyanopentanoyl chloride) and methacryloyl chloride. This macromonomeric azo initiator (MIM–PCL) was further used in the polymerization of styrene (St) or methylmethacrylate (MMA) via a radical initiated process at 60°C in bulk in order to obtain polystyrene (PS)-b-PCL or poly(methyl methacrylate) (PMMA)-b-PCL crosslinked block copolymers. Thermal decomposition kinetics of MIM–PCL and its copolymers were studied by using thermogravimetric analysis and differential scanning calorimetry (DSC). DSC traces of MIM–PCL showed two different exotherms, at 98 and 127°C. The first exotherm, observed at 98°C, was due to the polymerization of the terminal methacrylic groups; the other was due to the exothermic decomposition of azo groups of MIM–PCL. PCL-b-PS and PCL-b-PMMA crosslinked block copolymers showed single glass transition temperatures due to the compatibility of the crosslinked block segments. The polymer–solvent interaction parameter of PCL in chloroform was determined by vapor pressure osmometry to be 0.1 for the PCL–chloroform system at 30°C. The average molecular weights between junction points of crosslinked homo PCL were calculated by using the Flory–Rehner equation. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1149–1157, 1998     

Optical properties of CdxZn(1−x)O films deposited by ultrasonic spray pyrolysis method

Cd_xZn_(1−x)O (x = 0, 0.59, 0.78 and 1) films have been produced by ultrasonic spray pyrolysis technique using aqueous solutions of CdCl₂ H₂O and ZnCl₂ on the microscope glass substrate between 325 and 400 °C. The Cd_xZn_(1−x)O samples have been crystallized both cubic and hexagonal structures. The optical properties of the samples were characterized by transmittance and absorption spectroscopy measurements. Transmissions of the samples have decreased with increasing x values. The optical band gap energies of the Cd_xZn_(1−x)O samples from the absorption spectra have been calculated between 2.48 and 3.23 eV by different Zn contents. The samples were annealed at 350 and 450 °C. The optical band gap energy has decreased at 350 °C whereas it increased at 450 °C.     

On the geometry of isotropic arrays

We consider array geometries whose direction-of-arrival (DOA) estimation performance is isotropic. An isotropic array is one whose Cramer-Rao bound (CRB) on the DOA of a single source is uniform for all angles. For both planar arrays and volume arrays we derive necessary and sufficient conditions on array element locations so that the array is isotropic. We also present several designs of isotropic planar and volume arrays. The results apply to both narrowband and wideband scenarios. We analyze the special case where a planar array is used to estimate the DOA of three-dimensional (3-D) source. Finally, we compare isotropic array performance to the best possible array performance.     

Magnetic resonance imaging of proximal aortopulmonary window

Of the 187 cases of infantile choledochal cyst treated at our hospitals, we encountered 13 with spontaneous perforation. All cases were under 4 years old. Eight cases were found to have biliary peritonitis and 5 had a sealed perforation. The shape of the extrahepatic bile duct was cystic in 8 and fusiform in 5. The cyst wall around the perforation was filmy and bile was found to be oozing through the thinned wall. Nine perforations were single while 4 cases had multiple perforations. Four of 17 perforations occurred in the posterior part of the cyst wall. Only 1 case of perforation was associated with protein plugs in a common channel, while 7 of the 10 cases of choledochal cyst requiring percutaneous biliary drainage due to signs of raised intrabiliary pressure were found to have protein plugs. We consider that spontaneous perforation of a choledochal cyst is not rare in infancy. The etiology of a perforation must be epithelial irritation of the biliary tract due to refluxed pancreatic juice caused by pancreatico-biliary malunion associated with mural immaturity due to infancy, rather than an abnormal rise in ductal pressure or congenital mural weakness at a certain point.     

Electrospun porous cellulose acetate fibers from volatile solvent mixture

Electrospun porous cellulose acetate (CA) fibers were produced from highly volatile binary solvent system; dichloromethane(DCM)/acetone. The morphology and porous structure of CA fibers were highly dependent on DCM/acetone ratio and the concentration of the solutions. Ribbon-like porous CA fibers were obtained from 5% (w/v) to 10% (w/v) polymer solutions depending on the DCM/acetone ratio; 1/1, 2/1, 3/1 and 9/1 (v/v). Using higher DCM/acetone ratio resulted in bead-free fibers from less concentrated polymer solutions due to the high viscosity of the solutions, in addition, more porous CA fibers were obtained owing to the high volatility of DCM.