Short communication: Study on epilithic diatoms in the Kozluk Creek (Arapgir-Malatya, Turkey)

Being the most important members of phytoplankton and phytobenthos, both of which are the primary producers of surface water resources, algae play a very important role in the biological productivity of waters with their oxygen production through photosynthesis and they synthesize the organic materials. Furthermore, with their high levels of protein, algae are used as human and animal food as well as being used in the production of organic fertilizers and organic vitamins. Another reason for algae currently being among the most researched organisms is their easy and inexpensive productions in culture media. With the recognition of the importance of algae in standing waters and streams, the number of studies conducted on these organisms has rapidly increased. In Turkey, the number of studies on algae in streamsis quite high [(Altuner and Gurbuz (1989), Altuner and Gurbuz (1991) Yıldız (1991) , Yildiz and Ozkiran (1994), Ertan and Morkoyunlu (1998), Sahin (1998), Cetin and Yavuz (2001), Solak et al. (2012), Sivaci and Dere (2007), Mumcu et al. (2009), Pala and Caglar (2008)]

Gas and liquid-fuelled HVOF spraying of Ni50Cr coating: microstructure and high temperature oxidation

Ni50Cr thermally sprayed coatings are widely used for high temperature oxidation and corrosion in thermal power plants. In this study, a commercially available gas atomised Ni50Cr powder was sprayed onto a power plant alloy (ASME P92) using both gas and liquid fuelled high velocity oxy-fuel (HVOF) thermal spray. Microstructures of the two coatings were examined using SEM-EDX, XRD, oxygen content analysis and mercury intrusion porosimeter. The gas fuelled coating had higher levels of oxygen content and porosity. Shorter term air oxidation tests (4 h) of the free-standing deposits in a thermogravimetric analyser (TGA) and longer term air oxidation tests (100 h) of the coated substrates were performed at 700 °C. The kinetics of oxidation and the oxidation products were characterized in detail in SEM/EDX and XRD. In both samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of the coatings along with a small amount of NiO and NiCr2O4. Rietveld analysis was performed on the XRD data to quantify the phase composition of the oxides on both Ni50Cr coatings and their evolution with exposure time

Fabrication and microstrain evolution of Al-TiB2 composite coating by cold spray deposition

This paper investigates the microstructure evolution of Al-TiB2 coatings prepared by cold spraying. In situ Al-TiB2 composite powders containing uniformly distributed titanium diboride (TiB2) particles with a size range of 5 to 100 nm in the Al matrix and Al/Al-TiB2 blended powders were used as the cold spray feedstock for coating fabrication on aluminium alloy substrates. The microstructures of the feedstock powders and as-deposited coatings were characterised using scanning electron microscopy with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). Al/Al-TiB2 blended powder coatings, compromising closely packed powder particles, were sprayed to an approximate thickness of 500 μm. Al-TiB2 composite coatings (approximately 50 μm thick) were obtained retaining the microstructure of the composite powders being sprayed and no evidence of detrimental phase transformation was found. However, micro-cracks were found to exist in the Al-TiB2 coating due to the hardly deformable powder particles. Little or no microstrain was revealed in the as-sprayed Al-TiB2 coating, indicating that annealing may have occurred due to the localised adiabatic heating during the spraying process. It is demonstrated that it is possible to fabricate the Al-TiB2 composite coating by cold spray deposition but further improvements to eliminate coating cracking are required

Bond strength of plasma sprayed ceramic coatings on the phosphated steels

In the presented work, results of adhesion measurements for different systems of steel sheet-phosphate interlayer-ceramiccoating are described. The interlayers were produced by zinc phosphating; alumina, olivine and zirconiasilica-alumina (e.g. eucor) coatings were deposited by water stabilized plasma torch WSP®. However, successful application of the WSP technique depends on the choice of correct deposition parameters preserving the hydrated phosphates from thermal destruction by the molten ceramic particles. For the adhesion measurement ISO 4624standardized test was used. Corrosion resistivity was measured by polarisation resistance and free corrosion potential in 3 % NaCl solution. Key words

Application of HVOF WC-Co-Cr coatings on the internal surface of small cylinders: Effect of internal diameter on the wear resistance

Due to the restrictions and mediocre performance of current methods of coating complex shaped parts in which line of sight processes currently struggle, the development of new coating methods is essential, with High Velocity Oxy-Fuel (HVOF) thermal spray coatings being a good candidate. In this study, a new compact High Velocity Oxy-Air Fuel (HVOAF) thermal spray torch designed to coat internal surfaces was traversed within cylindrical pipes of internal diameters (IDs) of 70 mm, 90 mm and 110 mm and a WC-10Co-4Cr coating was applied with a commercially available powder feedstock. Powder and coating microstructures were analysed using SEM/EDX and XRD. Fracture toughness and microhardness of the coatings were measured, and dry sliding wear performance was investigated at two loads: 96 and 240 N. It was found that the coating sprayed at 90 mm (medium ID) had a lower specific wear rates at both test loads due to the highest fracture toughness and microhardness; whereas, the coating sprayed at 110 mm (high ID) showed the highest specific wear rates at both low and high conditions due to poor fracture toughness

Short communication: Study on epilithic diatoms in the Balikli Tohma Creek (Darende/Malatya in Turkey)

Water, being the source of life, contains many life forms. The number and diversity of algae, which constitutes the first link of the food chain, affect all living things within the aquatic environment including fish. With its streams and lakes that cover an area of approximately 10000 km2, Turkey has very important internal water resources. About 135 of the wetlands within the borders of Turkey have international importance. Twelve of those have been declared as Ramsar areas (Anonymous, 2009).The structure of diatom communities has been directly linked to the physical and chemical state of water. Therefore, diatoms are used in water quality calculations and comparisons among rivers that have different morpho¬dynamics (Allan, 1995). The Water Framework Directive has established diatom communities as an indicator for stream systems besides the physico¬chemical parameters (APHA, 1985). The inert algal species that typically cover stones and hard rocks, and exist in mucilaginous and filiform masses constitute the epilithic flora. There have been many studies in Turkey on epilithic and epiphytic diatoms. Some of those studies have been on rivers whereas some have been on creeks that periodically dry up or freeze (Altuner and Gurbuz, 1988; Dere and Sivaci, 1995; Yildiz and Atici, 1996; Pala and Caglar, 2006; Pala and Caglar, 2008; Cicek and Ertan, 2015)

Plasmid mediated resistance in multidrug resistant bacteria isolated from children with suspected septicaemia in Zaria, Nigeria

Septicaemia is a common cause of morbidity and mortality among children in the  developing world. The knowledge of the  epidemiological and antimicrobial pattern of common pathogens that cause septicaemia is useful for prompt treatment of patients. Fifty-five (55) clinical isolates from children with suspected septicaemia were used for the study. The isolates include Coagulase negative Staphylococcus, Staphylococcus aureus, Salmonella spp., Klebsiella spp., Citrobacter spp., Proteus spp and  Pseudomonas spp. The antibiotic susceptibility testing of isolated bacteria associated with septicaemia in children were carried out using standard  microbiological protocol. The MAR index for the test bacterial isolates was  determined and the bacterial isolates that displayed multiple antibiotic resistance were investigated for the presence of resistant factor such as plasmids. The sizes of the plasmid observed in the bacterial isolates were determined using agarose gel electrophoresis. Observations made from the agarose gel electrophoresis showed that majority of the multiple antibiotic resistant isolates haboured plasmids DNA of different sizes viz: 10.00 Kb, 8.71 Kb, 7.08 Kb, 1.02 Kb, 1.00 Kb, 0. 98 Kb and 0.87 Kb. The plasmid analysis of the results obtained in this study showed that the  predominant plasmid molecular size was 977bp which occurred frequently among  the Citrobacter spp and Staph aureus. These findings suggest an increased  resistance to the antibiotics commonly used for the treatment of septicaemia, and the observed presence of plasmids in some of the test bacteria isolated shows that they could have been acquired from multiple antibiotic resistant bacteria in the community under investigation.Key words: Children, Multiple antibiotic resistance, Plasmids, Septicaemi

Doğu Akdeniz Bölgesi’nde Organik Turunçgil Üretiminde Hastalık, Zararlı ve Yabancı Otların Mücadelesinin Yönetimi

Bu çalışma, 2003-2006 yılları arasında Hatay (Dörtyol) ve Mersin (Erdemli) illerinde yürütülmüş olup, çalışmada Mars Seedless Altıntop ve Valensiya Portakal çeşidinde zararlı, hastalık ve yabancı otlara karşı organik tarıma uygun mücadele yöntemlerinin uygulanabilirliği araştırılmıştır. Çalışmada her iki turunçgil çeşidinin bulunduğu alanlarda Organik Tarım ve Entegre Mücadele uygulamaları birlikte yürütülmüştür. Organik tarım yapılan bahçelerde organik ürün sertifikası alımına yönelik gerekli denetlemeler yaptırılarak ürün sertifikalandırılmıştır. Tüm bahçelerde bulunan zararlı ve doğal düşmanlar gözle inceleme ve darbe yöntemi ile saptanmıştır. Organik tarım bahçelerinde, ekonomik zarar eşiğini aşan zararlılara (Turunçgil Unlubiti, Turunçgil Kırmızı Örümceği, Yıldız Koşnili) karşı doğal düşman salımı, kükürt ve yazlık beyaz yağ uygulaması yapılarak mücadele edilmiştir. Hastalık etmenleri makroskopik ve mikroskobik incelemelerle belirlenmiştir. Denemenin yürütüldüğü Mars Seedless Altıntop bahçesinde Gövde Zamklanma Hastalığı [Phytopthora citropthora (Sm. et Sm) Leonian] tespit edilmiştir. Bu hastalıkla mücadele için enfekteli ağaçların gövdesinde kabuk temizliği yapılmış temizlenen yara yerlerine %2 oranında Bordo Bulamacı uygulanmıştır. Yabancı otlarla organik yetiştiricilikte mücadele amacıyla örtücü bitki uygulaması yapılmıştır. Dört örtücü bitki türü; arpa, İngiliz Çimi, Adi Fiğ, Acem Üçgülü denemeye alınmıştır. Toprağı kaplama alanı yönünden en yüksek değerler, ile yabancı ot kaplama alanı ve birim alandaki yabancı ot tür ve sayısı yönünden en düşük değerler arpa ve fiğden alınırken, yaş ve kuru ağırlık yönünden en yüksek değer yine fiğ parselinden elde edilmiştir. Bahçelerde Turunçgil Nematodu (Tylenchulus semipenetrans Cobb.) da belirlenmiş ancak populasyonları zarar eşiğinin altında bulunmuştur. Parsellerde kullanılan çiftlik gübresi ve yeşil gübre toprak ve yaprak analizleri sonuçlarına göre uygulanmıştır. Kullanılan her türlü girdiler ve yapılan işlemler Tarım Bakanlığınca yayımlanan yönetmeliğe uygun olarak kontrol ve sertifikasyon kuruluşunun da onayı ile seçilmiştir. Her yıl meyve hasat döneminde kalıntı analizleri ve pomolojik analizler yaptırılmış, bir üretim periyodu sonunda ağaç başına ortalama verim belirlenmiştir. Proje çalışmaları, ürüne “organik ürün” sertifikası veren danışman firma tarafından kontrol edilmiş ve çalışmada organik meyve elde edilmiştir

Small punch creep testing of thermally sprayed Stellite 6 coating: A comparative study of as-received vs post-heat treatment

Thermally sprayed Stellite 6 coatings offer high wear and corrosion-erosion resistance at high temperature but the creep behaviour of such coatings is not well understood. In this paper, the microstructure and creep behaviour of a HVOF Stellite 6 coating was investigated. The coating was tested in the as-sprayed condition and after an isothermal heat-treatment of 1 h at 1050 °C. The as-sprayed coating comprised FCC Co-Cr-W solid solution with 2–3 wt% HCP phase, whereas the heat-treated coating comprised FCC Co-Cr-W solid solution, 11 wt% M23C6 carbides and 7 wt% M7C3 carbides. Small punch creep tests were conducted at 700 °C on the as-sprayed and heat-treated coatings. The heat-treated coating exhibited minimum steady-state strain rates approximately 2 orders of magnitude lower than the as-sprayed coating when tested at similar loads, leading to times to failure approximately two orders of magnitude longer for the heat-treated coating within the selected load range. Fracture analysis showed cracking along powder particle boundaries was the main mode of cracking in the as-sprayed coating whereas for the heat-treated coating, fracture along the carbide / matrix interface was the main fracture mechanism

Dynamic beam steering with all-dielectric electro-optic III-V multiple-quantum-well metasurfaces

Tunable metasurfaces enable dynamical control of the key constitutive properties of light at a subwavelength scale. To date, electrically tunable metasurfaces at near-infrared wavelengths have been realized using free carrier modulation, and switching of thermo-optical, liquid crystal and phase change media. However, the highest performance and lowest loss discrete optoelectronic modulators exploit the electro-optic effect in multiple-quantum-well heterostructures. Here, we report an all-dielectric active metasurface based on electro-optically tunable III–V multiple-quantum-wells patterned into subwavelength elements that each supports a hybrid Mie-guided mode resonance. The quantum-confined Stark effect actively modulates this volumetric hybrid resonance, and we observe a relative reflectance modulation of 270% and a phase shift from 0° to ~70°. Additionally, we demonstrate beam steering by applying an electrical bias to each element to actively change the metasurface period, an approach that can also realize tunable metalenses, active polarizers, and flat spatial light modulators