Preparation and characterization of Bombyx mori silk fibroin and wool keratin

Silk and wool are well‐known protein‐based fibers. Their environmental stability, biocompatibility, and unique mechanical properties provide an important basis for using these natural proteins in biomedical applications. To use them as biomaterials in the form of fibers, films, or membranes, it is necessary to characterize these proteins in their solution and solid states because structural characteristics and morphological features have a great influence on the physical and mechanical properties of these new regenerated protein forms. Therefore, in the present study, silk fibroin and wool keratin were dissolved and their solution behaviors and secondary structures are analyzed and compared, using particle size distribution, molecular weight distribution (SDS‐PAGE), Fourier transform infrared, and X‐ray diffraction techniques. It was shown that keratin is more stable in solution and more amorphous in the solid state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4260–4264, 2006     

Oxidative coupling of methane over NbO (p-type) and Nb2O5 (n-type) semiconductor materials

Oxidative coupling of methane to higher hydrocarbons was investigated using two types of semiconductor catalysts, NbO (p-type) and Nb₂O₅ (n-type) at 1 atm pressure. The ratio of methane partial pressure to oxygen partial pressure was changed from 2 to 112 and the temperature was kept at 1023 K in the experiments conducted in a cofeed mode. The results indicated a strong correlation between C₂₊ selectivity performance and the electronic properties of the catalyst in terms of p-vs. n-type conductivity. The p-type semiconductor catalyst, NbO, had a larger selectivity (e.g. 95.92%) over the n-type Nb₂O₅ catalyst (23.08%) both at the same methane conversion of 0.64%. Catalyst characterization via X-ray diffraction, TGA and reaction studies indicated that NbO was transformed to Nb₂O₅ during the course of the reaction which limits catalyst life.     

Plasma sphingolipids in patients with sickle cell disease: Multiple-site vaso-occlusive crises could be associated with lower sphingolipid levels

Although sickle cell disease (SCD) and its manifestations have been associated with various lipid alterations, there are a few studies exploring the impact of sphingolipids in SCD. In this study, we determined plasma ceramide (Cer) and sphingomyelin (CerPCho) species and investigated their association with the crisis in SCD. SCD patients (N = 27) suffering from vaso-occlusive crisis (VOC) or acute chest syndrome (ACS) were involved in this study. Blood samples were drawn at crisis and later at steady state periods. Clinical history, white blood cell count (WBC), C-reactive protein and lactate dehydrogenase (LDH) levels were recorded. 16:0, 18:0, 20:0, 22:0 Cer and 16:0, 18:0, 24:0 CerPCho were measured via LC–MS/MS. All measured Cer and CerPCho levels of SCD patients at crisis and steady-state were found to be similar. Inflammation-related parameters were significantly higher in patients with ACS compared to single-site VOC. Patients with multiple-site VOC were found to have significantly lower sphingolipid levels compared with those with single-site VOC, at crisis (16, 18, 24 CerPCho and 18, 22 Cer) and at steady-state (24:0 CerPCho and 18 Cer). Our results show that sphingolipid levels in SCD patients are similar during crisis and at steady state. However, lower sphingolipid levels appear to be associated with the development of multiple-site VOC. Since the differences were observed at both crisis and steady-state, sphingolipid level could be an underlying factor associated with crisis characteristics in patients with SCD.     

Feature-based hybrid strategies for gradient descent optimization in end-to-end speech recognition

Multimedia Tools and Applications - With the increasing popularity of deep learning, deep learning architectures are being utilized in speech recognition. Deep learning based speech recognition...     

Risk assessment for sustainability in e-waste recycling in circular economy

Clean Technologies and Environmental Policy - E-waste is a hazardous concept for human health, environment and businesses, and therefore, risk assessment is essential to eliminate or reduce the...     

Theoretical study on the relationship between the molecular structure and corrosion inhibition efficiency of long alkyl side chain acetamide and isoxazolidine derivatives

Quantum mechanics calculations have been applied to three long alkyl side chain acetamides and three isoxazolidine derivatives used as corrosion inhibitors. The corresponding structures have been optimized, and the highest occupied molecular orbital energy (E _HOMO), the lowest unoccupied molecular orbital energy (E _LUMO), energy gap (??E), electronegativity (??), hardness (??), softness (??) and the fraction of electrons transferred from the inhibitor molecule to the metal surface (??N) have been calculated using the DFT/B3LYP and HF methods with the 6?C31G(d, p) basis set. The electric dipole moment (??), the mean polarizability (??????) and the first order hyperpolarizability (??) values of the investigated molecules have been computed using the same methods. The calculation results also show that the molecules might have microscopic nonlinear optical (NLO) behaviour with non-zero values. Finally, the theoretical results obtained have been compared with the experimental data.     

Effect of Various Processing Methods on Quality of Mackerel (Scomber scombrus)

The effects of combinations of processes (hot smoking, marinating, vacuum packing and seasoning with dill (Anethum graveolens) on the quality parameters of mackerel (Scomber scombrus) stored at 4 °C were investigated in terms of sensory, chemical (total volatile basic nitrogen [TVB-N], thiobarbituric acid [TBA], peroxide value [PV], free fatty acids [FFA]) and microbiological parameters (total viable count [TVC], coliform, Escherichia coli, Staphylococcus aureus) during 9 months of storage. Sensory quality of smoked mackerel marinates with or without dill leaves (Group A, Group B, respectively) decreased throughout storage period. However, at the end of storage period, both the products were still acceptable by the panellist. At the beginning of storage, the initial TVB-N values were 24.14 mg/100 g and showed fluctuations during storage period. TBA values significantly increased (p?<?0.05) for both products during storage period. PV showed fluctuations. FFA increased gradually from 2.46 to 7.33 (expressed as % of oleic acid) for Group A and from 2.57 to 6.90 for Group B at the end of storage period. Coliform, E. coli and S. aureus were not detected during storage period. TVC remained lower than the acceptability limit of 10⁶ log CFU/g at the end of storage period. The results of this study suggest that shelf life of both products was 9 months and also the combination of hot smoking, marinating, vacuum packing and seasoning led to high-quality food item and was found to be effective in controlling the growth of bacteria and biochemical indices.     

Biogenic amine content and biogenic amine quality indices of sardines (Sardina pilchardus) stored in modified atmosphere packaging and vacuum packaging

A comparative study of the effects of packaging on the formation of biogenic amines during storage of sardines (Sardina pilchardus) at 4 °C in air, modified atmosphere pack (MAP) and vacuum pack (VP) was carried out. Sardines were organoleptically acceptable for up to 3 days in air, 12 days in MAP and 9 days in VP. The biogenic amine content generally increased in all treatments with increasing storage time. The concentrations of putrescine and/cadaverine in fish stored in air reached maximum levels of 12.2 mg/100g at 12 days and 10.0 mg/l00 g at 15 days. Significant differences were found (P < 0.05) in the levels of cadaverine and putrescine among the three treatments. Spermidine and spermine levels increased slightly and did not change much throughout the storage period for all experimental conditions. The amine contents of sardine were highest in sardine stored in air, followed by VP and MAP. Quality indices related to the contents of the major biogenic amines were calculated and they correlated well with organoleptic qualities.