Films formed from polystyrene latex/clay composites: A fluorescence study

This study reports a steady-state fluorescence (SSF) technique for studying film formation from surfactant-free polystyrene (PS) latex and Na-montmorillonite (SNaM) composites. The composite films were prepared from pyrene (P)-labeled PS particles and SNaM clay at room temperature and annealed at elevated temperatures in 10-min intervals above glass transition temperature (t₃) of polystyrene. During the annealing processes, the transparency of the film improved considerably. Scattered light (I_s) and fluorescence intensity (I_p) from P were measured after each annealing step to monitor the stages of film formation. Evolution of transparency of composite films was monitored by using photon transmission intensity, I_tr. Scanning electron microscopy (SEM) was used to detect the variation in physical structure of annealed composite films. Minimum film formation temperature, T_q, and healing temperatures, T_h, were determined. Void closure and interdiffusion stages were modeled and related activation energies were determined. It was observed that both activation energies increased as the percent of SNaM was increased in composite films.     

Water–energy–food nexus in a transboundary context: the Euphrates–Tigris river basin as a case study

The interlinkage between water, energy and food security and its transboundary relevance is becoming increasingly important. The paper analyses the evolution of transboundary water resources management in the Euphrates–Tigris basin with specific reference to interlinkages between water, food and energy policies at national and transboundary levels, and it explores how the policy shifts at the highest decision-making level have served to produce synergies for cooperation among the riparians or vice versa.     

Utilising grape juice processing by-products as bulking and colouring agent in white chocolate

In this study, grape pomace (mixture of grape seeds and skins) powder (GPP), obtained from grape processing, was used at different concentrations [10.0 (GPP10), 20.0 (GPP10) and 30.0 (GPP10) g/100 g] in white chocolate formulation for the partial replacement of sucrose. The results indicated that GPP addition at a higher concentration (>10.0 g/100 g) significantly affected the particle size, moisture content, texture and flow behaviour of white chocolate samples (P < 0.05). However, using GPP at a concentration of 10.0 g/100 g had advantages for physicochemical and flow properties. As expected, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice and intestinal juice for GPP10 samples was significantly higher than the control (P < 0.05). In conclusion, results of the study showed that it was possible to partially replace the sucrose with GPP at a concentration of 10.0 g/100 g in white chocolate formulations.     

Investigation of using possibility of grape pomace in wafer sheet for wheat flour substitution

In this study, grape pomace (GP), a by-product consisting of grape skins and seeds rich in dietary fibres and polyphenols, was used in wafer sheets at different concentrations [5.00 (GP5), 10.0 (GP10), and 15.0 g 100 g⁻¹ (GP15)] for the partial replacement of wheat flour (WF) and improve the functionality of wafer sheets. The GP inclusion at concentrations higher than 5.00 g 100 g⁻¹ significantly affected the texture of sheets as well as the flow behaviour of batters, resulting in softer sheets and more viscous batters (P < 0.05). Moisture contents did not significantly change after GP addition (P > 0.05). After the addition of GP, the L* values decreased and the a* values increased, making the wafers darker (P < 0.05). Moreover, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice, and intestinal juice was significantly higher than control even at the lowest GP concentration (P < 0.05). Regarding sensory properties, only smoothness and crispness were significantly affected by GP addition, and samples were found to be crisper with higher concentrations of GP. In conclusion, it is possible to partially replace the WF in wafers with GP at a concentration of 5.00 g 100 g⁻¹ to develop a product with higher functionality and nutrient content.     

Using spray-dried sugar beet molasses in ice cream as a novel bulking agent

In this study, it is aimed to investigate and evaluate the use of molasses which is a by-product of sugar production as a novel bulking agent in ice cream as a sugar replacer. Sugar beet molasses (75%) and 12 DE maltodextrin (25%) were converted into powder form by spray drying. Spray-dried sugar beet molasses (SDSM) was then used as a substitute of sugar in different ratios (0:100, 25:75, 50:50, 75:25 and 100:0) in the ice cream products. The increased amount of SDSM decreased the overrun, L*, whiteness index (WI) and melting behaviours and increased a*, b*, total phenolic content, consistency and viscosity. Meanwhile, thermal properties have not been affected by the use of SDSM (P < 0.05). The sensory findings have been particularly interesting especially when replacing above 50% sugar with SDSM, aroma, flavour and general acceptability decrease. According to the results of this study, substituting 25% of total sugar with SDSM as a bulking agent can decrease cost of the product and improve total phenolic content and some quality parameters without compromising sensorial properties.     

Effect of molecular weight on the dissolution properties of polystyrene latex films

An in situ steady-state fluorescence (SSF) technique was applied in order to study the dissolution process of polystyrene (PS) latex films. The effect of the molecular weight M _w of the PS on the dissolution rate was investigated. The PS chains were copolymerized with (1-pyrene)methyl methacrylate in order to make use of pyrene (P) as a fluorescent probe to monitor the dissolution process. Seven different films were prepared from P-labeled PS latex dispersions with different molecular weights at room temperature. These films were then annealed at 200 °C for 15 min to complete the film formation process before dissolution. The dissolution of PS films in a toluene (70 %)–cyclohexane (30 %) mixture was monitored in real time by watching the change in the fluorescence intensity of P, I _P. We used a model that included both case I and case II diffusion kinetics to interpret the results of the dissolution experiments. The relaxation constants k ₀ and the dissolution coefficients D _d of the polymer chains were measured. Two different dissolution coefficients were obtained, which were attributed to the small and long polymer chains in the film, considering the high polydispersity of the polymer. It was also found that both of the D _d values scaled with M _w according to the law D _d ≈ M ^?n .     

A fluorescence study on dissolution of polymeric glasses prepared in various molecular weights

Poly(methyl methacrylate) (PMMA) discs in various molecular weights, M_w, were prepared by free-radical polymerization of methyl methacrylate (MMA). Pyrene (P) was introduced during polymerization as a fluorescence probe to monitor the gelation and dissolution processes in chloroform vapor and solvent, respectively. In-situ steady state fluorescence (SSF) experiments were performed to monitor vapor uptake and chain desorption processes. Direct illumination of PMMA discs were performed to excite the P molecules embedded inside the PMMA glass. Variation in P intensity, I, was monitored during the swelling of the PMMA material exposed to chloroform vapor. It was observed that PMMA film swells like a crosslinked polymeric gel at early times by obeying the Li-Tanaka equation. Swelling time constants, τ_c, of PMMA discs were measured and found to have a strong correlation with the molecular weight, of PMMA. In a separate experiment, when the PMMA discs were in chloroform, desorption of PMMA chains from glass discs was monitored by observing the change of pyrene fluorescence intensity. A diffusion model with a moving boundary was employed to quantify the fluorescence data observed from dissolving PMMA discs made at various molecular weights. It was observed that desorption coefficient, D, decreased by increasing M_w by obeying the D≈M_w ⁻¹ law. Presented at the 80th Annual Meeting of the Federation of Societies for Coatings Technology, October 30–November 1, 2002, New Orleans, LA. Department of Physics, 80626 Maslak, Istanbul. Turkey.     

Surfactant-Based Oil Extraction of Corn Germ

An aqueous surfactant-based extraction system was developed for the extraction of corn oil from corn germ with anionic extended surfactants. The surfactants used in this study were sodium linear-alkyl polypropoxylated polyethoxylated sulfates (C_12,14–P₁₀–E₂–SO₄Na and C₁₀–P₁₈–E₂–SO₄Na). Interfacial tension, critical microemulsion concentration (CμC), and optimum salinity values of the extended surfactants with corn oil were determined. In the extraction process, the ground corn germ was shaken with predetermined surfactant and salt concentrations at room temperature for 45 min. About 83%, the sum of total free oil and total oil-in-water emulsion, of the corn oil was extracted from the corn germ using a formulation of 0.4% C_12,14–P₁₀–E₂–SO₄Na and 1% NaCl. A solid/liquid ratio of 1/10 performed best for efficient oil recovery. The chemical compositions of the extracted corn oils were found to be similar to that of hexane extracted corn oil.     

Erythrocyte folate status and serum iron levels in patients undergoing hemodialysis

The present study was aimed to evaluate erythrocyte folate and the iron levels in diabetes and hypertension patients treated with/without hemodialysis. The effects of erythropoietin and iron treatment as well as vitamin supplementation on measured parameters were considered. The 67 controls consisted of healthy subjects (n = 22), hypertensive subjects (n = 22), and diabetic subjects (n = 23) without any renal disorder. According to primary renal disorders, the patients undergoing hemodialysis (n = 68) were classified into four groups as diabetic nephropathy, hypertensive nephropathy, reflux nephropathy or interstitial nephritis, and renal insufficiency depending on other causative factors. The mean value of erythrocyte folate levels of all patients undergoing hemodialysis was higher than the healthy control group (P < 0.05). Erythrocyte folate levels in hypertensive and diabetic nephropathy patients were higher than their own hypertensive or diabetic controls and also healthy controls (both, P < 0.05). Serum iron levels of all subgroups in hemodialysis patients were found to be similar with healthy controls (all, P > 0.05). The only significance observed within the subgroups was between diabetic controls and diabetic nephropathy patients (P < 0.05). None of the treatment or supplementation of erythropoietin, iron and vitamin affected erythrocyte folate levels (all, P > 0.05). The increase in erythrocyte folate status of patients with end stage renal diseases might be the result of sum or individual effects of causative factors such as renal pathology, compensation mechanism against renal anemia, or routine folate supplementation.     

Flow regimes in the emptying of pipes filled with a Herschel–Bulkley fluid

The emptying of pipework from fluids of high viscosity is a significant multiphase flow problem in many food and personal care industries. Maximising product recovery whilst minimising cleaning time and effluent volume is important in minimising the environmental footprint of the plant. The cleaning of pipework fully filled by toothpaste by water under different process conditions has been studied and monitored by weighing pipes at intervals. Three flow regimes have been identified; a short core removal stage of product recovery, before water breaks through the filled pipe, and two in subsequent cleaning, film removal when there is a continuous wavy annular film on the wall, and patch removal in which the material is present as patches on the wall. The amount of product recovered in core removal is here not a function of flow conditions; however, conditions during core removal significantly affect the overall cleaning time. Overall cleaning time can be reduced by at least 25% by selecting the best removal conditions in the different stages. It is hypothesised that this is due to changes in the wall layer induced during core removal, with a very wavy wall layer leading to rapid subsequent removal. If this effect could be understood and scaled up it may be possible to improve commercial cleaning processes.