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61.
Separation of aqueous dimethylformamide (DMF) solutions in the concentration range of 0-100 wt% were studied using sodium alginate (NaAlg)/polyvinyl pyrrolidone (PVP) blend membranes. The NaAlg was blended in different ratios with PVP. Prepared membranes were crosslinked with CaCl2 for testing in pervaporation (PV) separation of DMF/water mixtures. Effects of feed composition (0-100 wt%), operating temperature (30-50 °C), and membrane thickness were investigated. Best results were obtained at the conditions of 75/25 NaAlg/PVP blend ratio (w/w), 40 °C temperature, 20 wt% DMF concentration, and 70 μm membrane thickness. Blending of PVP with NaAlg increased permeation flux whereas it decreased the separation factor. NaAlg/PVP membranes gave separation factors of 5.5-27 for permeation flux of 0.96-1.81 kg/m2h depending on the operating temperature and the feed mixture composition. Arrhenius plot of permeation flux data versus reciprocal of temperature exhibited linear trends. Permeation activation energy of DMF and water in the PV was calculated as 6.76 and 1.88 kcal/mol, respectively, using an Arrhenius type relationship. Sorption-diffusion properties of the NaAlg/PVP membranes were also investigated at the operating temperature and the feed composition. 相似文献
62.
We investigated the publication trends in the international earth science literature coming out of Turkey in the period of
1970–2005 using the Science Citation Index Expanded database. A database of 2310 earth science publications with at least
one of the authors with an address in Turkey was compiled. The number of earth science publications from Turkey shows a very
rapid increase starting in the 1990’s in parallel with the increase in the total scientific output of Turkey. In the last
decade the annual growth rate has been 16%. There was also a concomitant increase in the number of citations. The causes of
the sharp increase in the publication numbers are, in order of importance, changes in the rules of academic promotion and
appointment, changes in academic attitudes towards publishing, increasing support for research, financial incentives for publishing,
and expansion of higher education. However, the sharp increase in the publication numbers was not accompanied by a similar
increase in the impact of the publications as measured by the citations. Although publications with first authors from outside
Turkey make up only 20% of the Turkish earth science publications in the period 1970–2005, these account for 38% of the total
citations, and constitute 48 out of 100 most cited papers. 相似文献
63.
In this study, we report on a unique, one-step fabrication technique enabling the simultaneous synthesis of vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with dual height scales through alcohol catalyzed chemical vapor deposition (ACCVD). Regions of VA-MWCNTs with different heights were well separated from each other leading to a self-patterning on the surface. We devised a unique layer-by-layer process for application of catalyst and inhibitor precursors on oxidized Si (100) surfaces before the ACCVD step to achieve a hierarchical arrangement. Patterning could be controlled by adjusting the molarity and application sequence of precursors. Contact angle measurements on these self-patterned surfaces indicated that manipulation of these hierarchical arrays resulted in a wide range of hydrophobic behavior changing from that of a sticky rose petal to a lotus leaf. 相似文献
64.
Ozkorkmaz EG 《Journal of electron microscopy》2011,60(4):261-265
Rats are widely used laboratory animals and have several parasites. One of these are helminths, known not only to cause serious effects on the experimental results in healthy subjects, but also in subjects with heavy infections. One of the relatively pathologic helminth is Trichosomoides crassicauda, which lives in the nodules of the urinary bladder. It is known that diabetics are more prone to infections with several microorganisms. Observations in a diabetic rat bladder showed T. crassicauda eggs inside the transitional epithelium, and structural changes in the bladder epithelium were evident. Urinary-bladder tissues taken from streptozotocin-injected diabetic subjects and citrate buffer-injected control subjects were fixed, embedded in araldite and investigated under a light microscope. Distinct changes in the histological structure of a diabetic urinary bladder transitional epithelium were observed after T. crassicauda infection. Many papillomas were formed and the epithelial tissues were completely degenerated. In addition, electron microscopic examinations also revealed degeneration of the subepithelial tissues. 相似文献
65.
66.
Tuba Şanli Asuman Gursel Ebru Şanli Esra Acar Mehlika Benli 《International Journal of Dairy Technology》2013,66(4):535-542
A mixed starter culture containing exopolysaccharide (EPS)‐producing strains of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was combined with Lactobacillus helveticus LH301 and used in the manufacture of low‐fat and reduced‐fat Kasar cheeses. For comparison, low‐fat (C10) and reduced‐fat (C20) cheeses were made using EPS‐producing (EPS+) starter strain and EPS‐non‐producing (EPS?) starter strain. The physicochemical properties of the cheeses were assessed in terms of chemical composition, texture, microstructure and microbial content over 90 days. Cheeses made with EPS‐producing culture (EPS10 and EPS20) had lower protein contents than control cheeses with 10% and 20% fat in dry basis (C10 and C20). Scanning electron microscopy images showed that using EPS‐producing culture resulted in a less compact protein matrix and sponge‐like structure in the cheese samples. In general, cheeses made using EPS‐producing culture had lower total viable counts. This could be related to the reduced survivability of EPS‐producing cells in the cheese matrix during ripening due to autolysis ability. 相似文献
67.
Bismuth nano-Hall probes with dimensions ~120 × 120 nm were fabricated by focused ion beam milling and used for the direct room temperature magnetic imaging of crystalline garnet thin films and strontium ferrite permanent magnets by scanning Hall probe microscopy. At driving currents of 40 μA, the Hall coefficient and magnetic field sensitivity of the Bi nano-Hall probes were 3.3 × 10-4 Ω/G and 7.2 G/√Hz, respectively 相似文献
68.
In this study, we investigated whether wild-thyme (Thymus serpyllum) hydrosol had a preserving effect against spoilage of freshwater fish. Sensorial characteristics, chemical freshness indicator contents, and microbial counts (total aerobes, psychrotrophics, Enterobacteriaceae, fecal coliform bacteria, Aeromonas spp., and Pseudomonas spp.) of whole ungutted and gutted Transcaucasian barb (Capoeta capoeta capoeta Guldenstaedt, 1772) stored on ice produced from wild-thyme hydrosol and tap water at 4 degrees C for 20 days were compared. The results did not reveal any significant (P > 0.05) differences in the microbial counts, sensorial characteristics, pH, and total volatile basic nitrogen values between gutted and ungutted groups. Sensory evaluation and microbiological and chemical analyses indicated that the storage of the fish on ice produced from wild-thyme hydrosol had a significant increase in shelf life by at least 15 to 20 days. 相似文献
69.
Russian Journal of Nondestructive Testing - Alcohol is widely used in various fields today. Alcohol overdose and its improper use can cause many health problems. Drinking liquids with high alcohol... 相似文献
70.
Mutay Aslan Ebru Kıraç Sabriye Kaya Filiz Özcan Ozan Salim Osman Alphan Küpesiz 《Lipids》2018,53(3):313-322
Limited data are available on the serum levels of different sphingomyelin (CerPCho) and ceramide (CER) species in sickle‐cell disease (SCD). This study was aimed at identifying the levels of C16–C24 CerPCho and C16–C24 CER in serum obtained from SCD patients and controls. Circulating levels of neutral sphingomyelinase (N‐SMase) activity, ceramide‐1‐phosphate (C1P), and sphingosine‐1‐phosphate (S1P) were also determined. Blood was collected from 35 hemoglobin (Hb)A volunteers and 45 homozygous HbSS patients. Serum levels of C16–C24 CerPCho and C16–C24 CER were determined by an optimized multiple reaction monitoring (MRM) method using ultrafast liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Serum activity of N‐SMase was assayed by standard kit methods, and C1P and S1P levels were determined by enzyme‐linked immunosorbent assay. A significant decrease was observed in the serum levels of C18–C24 CerPCho in patients with SCD compared to controls. No significant difference was found in C16 CerPCho levels between the two groups. Very‐long‐chain C22–C24 CER were significantly decreased in SCD, while long‐chain C16–C20 CER levels showed no significant difference between SCD patients and controls. Significant positive correlation was found between the serum total cholesterol levels and C18–C24 CerPCho and C22–C24 CER in SCD patients. Patients with SCD had significantly elevated serum activity of N‐SMase as well as increased circulating levels of C1P and S1P compared to controls. The decrease in serum levels of C18–C24 CerPCho in patients with SCD was accompanied by decreased levels of C22–C24 CER. Future studies are needed to understand the role of decreased CerPCho and CER in the pathophysiology of SCD. 相似文献