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There is growing evidence for the involvement of sex hormones in the pathogenesis of keratoconus. This study aimed to evaluate serum androgen and prolactin levels in patients suffering from keratoconus. One hundred and two subjects were enrolled in the keratoconus (76 patients) and control (26 subjects) groups in a cross-sectional survey. Topographic evaluation of the cornea was undertaken for all enrolled participants. Serum testosterone, dehydroepiandrosterone sulphate (DHEAS), prolactin (PRL), luteinising hormone (LH), and follicle-stimulating hormone (FSH) were measured in all subjects. There was no significant difference in demographic characteristics between the study groups. Significantly higher mean serum levels of DHEAS (3.71 ± 2.23 vs. 2.53 ± 1.77 µg/mL; P = 0.009) and T (6.18 ± 3.80 vs. 1.57 ± 1.76 ng/mL; P < 0.001) were observed in men with keratoconus compared to controls. In females, there were also higher mean levels of DHEAS (2.40 ± 1.57 vs. 2.18 ± 0.72 µg/mL; P = 0.355) and T (0.78 ± 0.96 vs. 0.32 ± 0.13 ng/mL; P < 0.001) in patients with keratoconus but only T level reached the statistically significant level of difference. Also, the mean serum PRL level was significantly higher in women with keratoconus compared to control (13.33 ± 17.85 vs. 4.63 ± 3.10 ng/mL; P < 0.001). There was no significant difference between serum FSH and LH levels between study groups. In patients with keratoconus, serum PRL in females and serum androgen levels in both genders are elevated. [ABSTRACT FROM AUTHOR]

Pathogenic strains of Escherichia coli infecting poultry, commonly called avian pathogenic E. coli (APEC) present significant risks, to the health of both poultry and the general public. This systematic review aimed to examine the prevalence of APEC serotypes, sequence types (ST), phylogenetic groups, virulence factors and antibiotic resistance patterns based on 189 research papers sourced from PubMed, Web of Science, and ProQuest. Then, data were extracted from the selected studies and analyzed to assess the global distribution and characteristics of APEC strains. The metaprop codes in the Meta and Metafor packages of R as implemented in RStudio were then used to conduct meta-analysis. Among APEC strains identified from these different research reports serogroup O78 had the highest overall prevalence (16 %), followed by serogroups O2 (10 %), and O117 (8 %). The most common ST profiles were ST117 (20 %), ST140 (15 %), ST95 (12 %), and ST131 (9 %). ST117 and ST140 are known reservoirs for pathogenic E. coli in humans. Moreover, phylogenetic assessment highlighted the prevalence of phylogroups A, A1, F, D, and B2 among APEC strains indicating diversity in phylogenetic origin within poultry populations. The presence of antimicrobial resistance was notable among APEC strains against antibiotics such as tetracyclines, penicillins, and cephalosporins. This resistance may be linked to use of antimicrobials in poultry production in certain regions presenting challenges for both animal health management and human infection control. Analysis of sequences linked to adherence or virulence indicated that genes encoding adhesins (csg, fimC), iron/metal uptake (sitB, sitC, iroD) and cytotoxicity (estB, hlyF), and serum resistance (traT, iss) were highly prevalent. These factors have been reported to contribute to APEC host colonization and virulence in poultry. In summary, this overview of the characteristics of APEC highlights the pressing importance of monitoring and implementing management approaches to reduce antimicrobial resistance considering that a phylogenetic diversity of E. coli strains causes infections in both poultry and humans and represents a risk to both animal and public health. Further, determining the major conserved aspects and predominant mechanisms of virulence of APEC is critical for improving diagnostics and developing preventative measures to reduce the burden of infection caused by pathogenic E. coli in poultry and lower risks associated with foodborne transmission of E. coli to humans through poultry and poultry products. • High prevalence of O78, O2 and O117 among APEC strains isolated from clinical cases. • ST117, ST140, and ST95 are the most common ST profiles among APEC strains. • Phylogenetic group A, A1, F, D, and B1 are predominant among APEC strains. • A high level of antimicrobial resistance is observed among APEC strains. • Csg, fimC, sitB, sitC, iroD, estB, and hlyF genes are prevalent among APEC strains. [ABSTRACT FROM AUTHOR]

This research has investigated the optical properties of zinc sulfide commercial powder sintered via hot pressure (HP) and spark plasma sintering (SPS) methods. SEM images indicated that zinc sulfide commercial powder had spherical morphology, whereby nano rods smaller than 100 nm formed on spherical particles. Investigation of optical properties indicated that the zinc sulfide transparent ceramic prepared via HP (75%) had higher infrared transmission as compared to SPS (69%) within 8–12 micrometer. The stoichiometric ratio of S to Zn in the commercial powder was 1.5, which decreased to 1.1–1.3 after the sintering process. [ABSTRACT FROM AUTHOR]

To report two cases of suprachoroidal hemorrhage during otherwise uncomplicated phacoemulsification, in whom COVID‐19 was documented with a positive PCR test about 1 month before the surgery and the importance of postponing elective surgeries for several months after infection. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose is to compare the clinical results of using silk versus nylon sutures for conjunctival autograft suturing in pterygium surgery. METHODS: In this prospective, randomized, controlled, clinical trial 50 eyes from 50 patients with primary nasal pterygium were randomized to undergo pterygium surgery with the use of either nylon sutures or silk sutures for conjunctival autograft suturing. Patients were followed up for 6 months. Main outcome measures included recurrence, postoperative discomfort according to a visual analog scale (VAS), graft hyperemia, and graft edema. RESULTS: According to the results, there was no significant difference between groups regarding recurrence rate of pterygium (P = 0.72). A significant decrease in the mean VAS discomfort score from day 1 to day 14 was observed in both groups (P = 0.001); postoperative discomfort during the first 2 weeks, was not significantly different between the two groups. At 2 weeks' postoperatively, significantly greater number of nylon sutures remained on the autograft (P = 0.021), some of which were buried and could not be removed. CONCLUSION: Both silk and nylon are effective suture materials for autograft suturing in pterygium surgery with similar postoperative discomfort and recurrence rate. Significantly greater number of nylon sutures remains buried on the autograft and could not be removed easily. [ABSTRACT FROM AUTHOR]

Bacteriocins are antimicrobial compounds with targeted activities that are produced by a variety of bacterial species. Different aspects of bacteriocins were intensively studied and highlighted in previous research publications. Developments in this field are best demonstrated through analysis of the most cited scientific literature concerning bacteriocins. The objective of this report was to identify and establish main characteristics of the 100 top-cited papers presenting research on bacteriocins. Publications regarding bacteriocins between 1970 and 12th May 2017 were retrieved from the Web of Knowledge database of the Institute of Scientific Information. From this list, the top-cited 100 papers in the field of bacteriocins were established. The top-cited papers in this field were published from 1991 to 2013 and, as of this date, they have received from 85 to 1097 citations. The average citation rate of the 100 top-cited papers was 166.23 times (SD 136.87). The most common fields of study were microbiology (45%), biochemistry and molecular biology (35%), and biotechnology and applied microbiology (26%). Among the top-cited papers, 24 and 17 papers originated from the United States and Germany, respectively. Among these top-cited papers close to 80% concerned mainly bacteriocins from Gram-positive bacteria, whereas, only nine of the top-cited papers described bacteriocins of Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance, genotype, and virulence gene content of Escherichia coli isolated from bovine clinical mastitis in Tehran Province, Iran, were studied. Two hundred seven (207) milk samples from individual cows presenting mastitis symptoms collected from different dairy farms were used to determine the presence of specific genes of E. coli responsible for this pathology. Multiplex PCR was used to differentiate E. coli isolates into different phylogenetic groups/subgroups and to detect their virulence and involved resistance genes. All the isolated strains were tested for the susceptibility to 21 antimicrobial agents. The results showed that E. coli was detected in 42 (20.3%) samples and 69% of them belonged to the phylogenetic groups A and B1. The phylogenetic subgroup A1 (31%) and subgroup B1 (28.6%) demonstrated the highest prevalence of virulence genes (f17c‐A, and eae (n = 6), f17b‐A, and f17d‐A (n = 5), afaD‐8, afaE‐8, aucD, and bfpA (n = 4), clpG and VT (n = 2), and LT and ST genes (n = 1)). The highest antimicrobial resistance was observed for tetracycline (45.2%) followed by streptomycin (26.2%). The antimicrobial resistance genes tetB (31%), tetA (28.6%), and aadA (26.2%) were the most prevalent. Moreover, integron class 1 and 2 were found in 24 (57.1%) and 8 (19%) of the E. coli isolates. [ABSTRACT FROM AUTHOR]

Clinical mastitis (CM) is one of the most frequent and costly diseases in dairy cows. A frustrating aspect of CM is its recurrent nature. This review was conducted to synthesize knowledge on risk of repeated cases of CM, effects of recurrent CM cases, and risk factors for CM recurrence. A systematic review methodology was used to identify articles for this narrative review. Searches were performed to identify relevant scientific literature published after 1989 in English or French from 2 databases (PubMed and CAB Abstracts) and 1 search platform (Web of Science). Fifty-seven manuscripts were selected for qualitative synthesis according to the inclusion criteria. Among the 57 manuscripts selected in this review, a description of CM recurrence, its risk factors, and effects were investigated and reported in 33, 37, and 19 selected manuscripts, respectively. Meta-analysis and meta-regression analyses were used to compute risk ratio comparing risk of CM in cows that already had 1 CM event in the current lactation with risk of CM in healthy cows. For these analyses, 9 manuscripts that reported the total number of lactations followed and the number of lactations with ≤1 and ≤2 CM cases were used. When summarizing results from studies requiring ≥5 d between CM events to consider a CM event as a new case, we observed no significant change in CM susceptibility following a first CM case (risk ratio: 0.99; 95% confidence interval: 0.86–1.14). However, for studies using a more liberal CM recurrence definition (i.e., only 24 h between CM events to consider new CM cases), we observed a 1.54 times greater CM risk (95% confidence interval: 1.20–1.97) for cows that already had 1 CM event in the current lactation compared with healthy cows. The most important risk factors for CM recurrence were parity (i.e., higher risk in older cows), a higher milk production, pathogen species involved in the preceding case, and whether a bacteriological cure was observed following the preceding case. The most important effects of recurrent CM were the milk yield reduction following a recurrent CM case, which was reported to be similar to that of the first CM case, and the increased risk of culling and mortality, which were reported to surpass those of first CM cases. [ABSTRACT FROM AUTHOR]

In the current study, amorphous/nanocrystalline Ge 1 − x C x films were prepared by plasma enhanced chemical vapor deposition (PECVD), and the effect of carbon content on their phase structure was investigated. Elemental investigation by using Rutherford backscattering spectroscopy (RBS) and structural evaluation by employing X-ray diffraction (XRD), Raman spectroscopy and high resolution transition electron microscopy (HR-TEM) were performed. The results suggested that the Ge 1 − x C x films in the form of a composite structure, affected by the carbon contribution in the film, could comprise various fractions of amorphous and/or nanocrystalline germanium and amorphous carbon. With enhancing the carbon content, the crystallinity degree of the films was decreased due to increase of the volume fraction of the amorphous carbon and the intensification of the hydrocarbon radical role during the growing process. [ABSTRACT FROM AUTHOR]

Germanium-carbon coatings were deposited on silicon and glass substrates by plasma enhanced chemical vapor deposition (PECVD) using three different flow ratios of GeH 4 and CH 4 precursors. Elemental analysis, structural evaluation and microscopic investigation of coatings were performed using laser-induced breakdown spectroscopy (LIBS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. Based on the results, the coatings exhibited a homogeneous and dense structure free of pores with a very good adhesion to substrate. The structural evaluation revealed that the germanium-carbon coatings were a kind of a Ge-rich composite material containing the amorphous and crystalline germanium and amorphous carbon with the mixture of Ge–Ge, Ge–C, C–C, Ge–H and C–H bonds. The result suggested that the amorphisation of the coatings could be increased with raising CH 4 :GeH 4 flow rate ratio and subsequently increasing C amount incorporated into the coating. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the prevalence and antimicrobial resistance of Staphylococcus aureus isolated from raw milk (cow and sheep) and dairy products (traditional cheese and kashk) in Mazandaran Province, Iran. A total of 2650 samples, including 1930 raw milk and 720 dairy products were purchased from retail stores. Out of 2650 samples, S. aureus was detected in 328 samples (12.4%) in which 53 (16.2%) were positive for methicillin-resistant S. aureus. The S. aureus isolates showed resistance to tetracycline (56.1%), followed by penicillin G (47.3%), oxacillin (16.2%), lincomycin (11.9%), clindamycin (11.3%), erythromycin (7.9%), streptomycin (5.8%), cefoxitin (5.5%), kanamycin (4%), chloramphenicol (3.7%), and gentamicin (2.1%). A high frequency of blaZ (46%) and tetM (34.8%) resistance genes was found in S. aureus isolates. The findings of this study revealed consumption of raw milk and dairy products as a potential risk of foodborne infection in this region. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the prevalence and characterization of Listeria species and Listeria monocytogenes isolated from raw fish and open-air fish market environments. Eight hundred and sixty two samples including raw fish and fish market environments (samples from workers' hands, workers' knives, containers and work surface) were collected from the open-air fish markets in the Northern region of Iran. Results: Listeria spp. was isolated from 104/488 (21.3 %) raw fish and 29/374 (7.8 %) of samples from open-air fish market environment. The isolates of Listeria spp. included L. innocua (35.3 %), L. monocytogenes (32.3 %), L. seeligeri (18 %), and L. ivanovii (14.3 %). Of the 43 L. monocytogenes isolates, 31 (72.1 %), 10 (23.3 %) and 2 (4.7 %) belonged to serovars 1/2a, 4b, and 1/2b, respectively. The inlA, inlB, inlC, inlJ, actA, hlyA, iap, plcA, and prfA virulence-associated genes were detected in almost all of the L. monocytogenes isolates. The Listeria spp. isolates showed high resistance against tetracycline (23.3 %), penicillin G, and cephalothin (each 16.5 %). Besides, we observed significant resistance level to tetracycline (27.9 %), ampicillin (20.9 %), cephalothin, penicillin G, and streptomycin (each 16.3 %) in the L. monocytogenes isolates. All of the isolates were susceptible to cefotaxime, gentamicin, kanamycin, and pefloxacin. We found that tetM (25.6 %), tetA (23.3 %), ampC (14 %), and penA (11.6 %) were the most prevalent antibiotic resistance genes in the L. monocytogenes isolates. Conclusions: Recovery of potentially pathogenic L. monocytogenes from raw fish and environment of open-air fish market samples in this study is a convincing evidence for the zoonotic potential of listeriosis. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the prevalence and characterization of Listeria species and Listeria monocytogenes isolated from raw fish and open-air fish market environments. Eight hundred and sixty two samples including raw fish and fish market environments (samples from workers’ hands, workers’ knives, containers and work surface) were collected from the open-air fish markets in the Northern region of Iran. Results: Listeria spp. was isolated from 104/488 (21.3 %) raw fish and 29/374 (7.8 %) of samples from open-air fish market environment. The isolates of Listeria spp. included L. innocua (35.3 %), L. monocytogenes (32.3 %), L. seeligeri (18 %), and L. ivanovii (14.3 %). Of the 43 L. monocytogenes isolates, 31 (72.1 %), 10 (23.3 %) and 2 (4.7 %) belonged to serovars 1/2a, 4b, and 1/2b, respectively. The inlA, inlB, inlC, inlJ, actA, hlyA, iap, plcA, and prfA virulence-associated genes were detected in almost all of the L. monocytogenes isolates. The Listeria spp. isolates showed high resistance against tetracycline (23.3 %), penicillin G, and cephalothin (each 16.5 %). Besides, we observed significant resistance level to tetracycline (27.9 %), ampicillin (20.9 %), cephalothin, penicillin G, and streptomycin (each 16.3 %) in the L. monocytogenes isolates. All of the isolates were susceptible to cefotaxime, gentamicin, kanamycin, and pefloxacin. We found that tetM (25.6 %), tetA (23.3 %), ampC (14 %), and penA (11.6 %) were the most prevalent antibiotic resistance genes in the L. monocytogenes isolates. Conclusions: Recovery of potentially pathogenic L. monocytogenes from raw fish and environment of open-air fish market samples in this study is a convincing evidence for the zoonotic potential of listeriosis. [ABSTRACT FROM AUTHOR]

The aims of this study were to investigate the prevalence and to characterize and determine the antibiotic resistance of Yersinia spp. isolates from raw milk. From September 2008 to August 2010, 446 raw milk samples were obtained from farm bulk milk tanks in Varamin, Iran. Yersinia spp. were detected in 29 (6.5%) samples, out of which 23 (79.3%), 5 (17.2%), and 1 (3.4%) were isolated from cow, sheep, and goat raw milk, respectively. The most common species isolated was Yersinia enterocolitica (65.5%), followed by Yersinia frederiksenii (31%), and Yersinia kristensenii (3.4%). Of the 19 Y. enterocolitica isolates, 14 (73.7%) were grouped into bioserotype 1A/O:9, 4 (21.1%) belonged to bioserotype 1B:O8, 1 (5.3%) belonged to bioserotype 4/O:3, and 1 isolate (biotype 1A) was not typable. All the isolates of biotypes 1B and 4 harbored both the ystA and ail genes. However, all the isolates of biotype 1A were only positive for the ystB gene. The tested Yersinia spp. showed the highest percentages of resistance to tetracycline (48.3%), followed by ciprofloxacin and cephalothin (each 17.2%), ampicillin (13.8%), streptomycin (6.9%), and amoxicillin and nalidixic acid (each 3.4%). All of the tested isolates demonstrated significant sensitivity to gentamicin and chloramphenicol. Recovery of potentially pathogenic Y. enterocolitica from raw milk indicates high risks of yersiniosis associated with consumption of raw milk. [ABSTRACT FROM AUTHOR]

Abstract: Listeria monocytogenes is an important foodborne pathogen. The aims of this study were to determine genetic relatedness of L. monocytogenes isolated from ready-to-eat (RTE) foods in Malaysia. L. monocytogenes isolates from RTE foods were characterized by multiplex-PCR serotyping, REP-PCR, BOX-PCR, RAPD, PFGE, virulotyping and antibiotyping. Of the 32 L. monocytogenes isolates analyzed, 21 (65.6%) were assigned to serogroup “1/2a, 3a”, seven (21.9%) serogroup “1/2c, 3c”, and four (12.5%) serogroup “4b, 4d, 4e”. All the L. monocytogenes harbored inlA, inlB, inlC and inlJ virulence genes. More than half (53%) L. monocytogenes isolates were resistant to penicillin G, followed by tetracycline (15.6%), amoxicillin-clavulanic acid (12.5%), vancomycin (9.4%) erythromycin (6.3%), clindamycin, streptomycin, kanamycin, and chloramphenicol (each 3.1%). REP-PCR, BOX-PCR, RAPD and PFGE generated 28 (D = 0.992), 31 (D = 0.998), 32 (D = 1), and 20 (D = 0.916) patterns, respectively. These results indicate that L. monocytogenes isolates from RTE food were heterogeneous. There was no correlation between antibiograms and serogroups or pulsotypes or PCR-typing and/or sources of isolates. Since different subtyping methods often give different discriminatory powers, the use of more than one subtyping approach is necessary in providing a more accurate picture of the genetic diversity of L. monocytogenes. In conclusion, L. monocytogenes isolates from RTE possess the internalin genes and are genetically diverse. Furthermore, the occurrence of resistant isolates belonging to epidemiologically important serogroups “1/2a, 3a” and “4b, 4d, 4e” in RTE foods is a matter of public health concern. [Copyright &y& Elsevier]

The aims of this study were to determine the prevalence and antibiotic resistance of Staphylococcus aureus isolated from bovine clinical mastitis in Varamin, Tehran Province, Iran. All of the isolated Staph. aureus were identified by morphology and culture and confirmed using the API Staph identification system (bioMérieux, Marcy-l'Étoile, France). Antibiotic resistance genes were detected by PCR with oligonucleotide primers specific for each gene. Staphylococcus aureus was recovered from 43 of 207 (20.1%) bovine clinical milk samples. Using disk diffusion, methicillin-resistant Staph. aureus was detected in 5 of 43 (11.6%) samples. The pathogen showed high resistance against penicillin G (86%) and tetracycline (76.7%). The blaZ (penicillin) (86%), tetM (tetracycline), and ermC (erythromycin) genes (39.5% each) were the most prevalent antibiotic resistance genes. The findings of this study are useful for designing specific control programs for bovine clinical mastitis caused by Staph. aureus in this region of Iran. [ABSTRACT FROM AUTHOR]

The aims of this study were to determine the prevalence and antimicrobial resistance of Listeria, Salmonella, and Yersinia spp. isolated from duck and goose intestinal contents. A total of 471 samples, including 291 duck and 180 goose intestinal contents, were purchased from wet markets between November 2008 and July 2010. Listeria, Salmonella, and Yersinia spp. were isolated from 58 (12.3%), 107 (22.7%), and 80 (17%) of the samples, respectively. It was concluded that Listeria ivanovii, Salmonella Thompson, and Yersinia enterocolitica were the predominant serovars among Listeria, Salmonella, and Yersinia spp., respectively. Moreover, resistance to tetracycline was common in Listeria (48.3%) and Salmonella spp. (63.6%), whereas 51.3% of the Yersinia spp. isolates were resistant to cephalothin. Therefore, continued surveillance of the prevalence of the pathogens and also of emerging antibiotic resistance is needed to render possible the recognition of foods that may represent risks and also ensure the effective treatment of listeriosis, salmonellosis, and yersiniosis. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the current study was evaluation and comparison of hot corrosion behaviors of plasma-sprayed conventional and nanostructured yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). Hot corrosion studies were performed on the surface of coatings in the presence of a molten mixture of V2O5+Na2SO4 at 1000°C for 30h. Results indicated that the hot corrosion mechanisms of conventional and nanostructured YSZ coatings were similar. The reaction between corrosive salt and Y2O3 produced YVO4, leaching Y2O3 from YSZ and causing the detrimental phase transformation of zirconia from tetragonal to monoclinic. The nanostructured coating, as compared to its conventional counterpart, in spite of a further reaction with the corrosive salt, showed a higher degradation resistance during the hot corrosion test due to increased compliance capabilities resulting from the presence of an extra source of porosity associated with the nano-zones. [Copyright &y& Elsevier]

Abstract: A total of 446 various raw milk samples were collected from numerous farm bulk milk tanks to examine the presence of Listeria species. These isolates were further characterised by biochemical tests and Polymerase Chain Reaction (PCR). Listeria spp. was isolated in 83 of the 446 samples (18.6%). The highest prevalence of Listeria spp. was detected in raw cow milk samples (22.5%), followed by raw sheep milk (16.4%) and raw goat milk (4.9%). The most common species isolated was Listeria innocua (57.8%); the remaining Listeria isolates were Listeria monocytogenes (21.7%), Listeria welshimeri (12%), and Listeria seeligeri (8.4%). Based on PCR serotyping, the 18 L. monocytogenes isolates were distributed into three serogroups “1/2a, 3a” (n = 11), “1/2c, 3c” (n = 5), and “4b, 4d, 4e” (n = 2). All the examined L. monocytogenes were positive for internalin genes (inlA, inlC, and inlJ). The Listeria spp. isolates were resistant to tetracycline (49.4%) and penicillin G (43.4%) but remained susceptible to gentamicin, vancomycin and rifampicin. The findings of this study show that consumption of raw milk could be a potential risk of human listeriosis. [Copyright &y& Elsevier]

Abstract: The objectives of this study were to determine the prevalence of Listeria spp., specifically Listeria monocytogenes in ready-to-eat (RTE) foods and ascertain the efficiency of detecting L. monocytogenes with different selective culture media. A total of 396 RTE food samples were purchased from hypermarkets and streetside hawker stalls to examine the presence of Listeria spp. and L. monocytogenes. The presumptive isolates were characterized biochemically and were further confirmed by Polymerase Chain Reaction (PCR). Out of 396 samples, Listeria spp. was detected in 71 (17.9%) samples in which 45 (11.4%) were positive for L. monocytogenes. Among the studied RTE foods, salads and vegetables had the highest prevalence (14.7%) of L. monocytogenes, followed by chicken and chicken products (13.2%), beverages (10%), eggs and egg products (9.5%), beef and beef products (6.7%), lunch boxes (6.7%) and seafood and seafood products (6.7%). Both Listeria selective agar and PALCAM agar displayed a low sensitivity and specificity in L. monocytogenes detection compared to CHROMagar™Listeria which demonstrated 96.9% of sensitivity and 99.1% of specificity in L. monocytogenes detection in naturally-contaminated foods. In conclusion, this work revealed consumption of RTE foods as a potential risk of listeriosis in this region. The high contamination rate of L. monocytogenes in salads and vegetables from hypermarkets and streetside hawker stalls was of great concern due to emerging fresh produce-borne L. monocytogenes globally. The scenario warrants further surveillance and action by the local authority to control the incidence of L. monocytogenes contamination in RTE foods. [Copyright &y& Elsevier]

Abstract: The main goal of the current study is evaluation and comparison of thermal shock behavior of plasma-sprayed nanostructured and conventional yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). To this end, the nanostructured and conventional YSZ coatings were deposited by atmospheric plasma spraying (APS) on NiCoCrAlY-coated Inconel 738LC substrates. The thermal shock test was administered by quenching the samples in cold water of temperature 20–25°C from 950°C. In order to characterize elastic modulus of plasma-sprayed coatings, the Knoop indentation method was employed. Microstructural evaluation, elemental analysis, and phase analysis were performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) respectively. The results revealed that failures of both nanostructured and conventional TBCs were due to the spallation of ceramic top coat. Thermal stresses caused by mismatch of thermal expansion coefficients between the ceramic top coat and the underlying metallic components were recognized as the major factor of TBC failure. However, the nanostructured TBC, due to bimodal unique microstructure, presented an average thermal cycling lifetime that was approximately 1.5 times higher than that of the conventional TBC. [Copyright &y& Elsevier]

A total of 471 duck and goose intestinal content samples were collected from wet markets and were determined for the prevalence of Campylobacter spp. For the detected isolates, resistance to selected antimicrobial agents was identified. Campylobacter spp. was detected in 114/291 duck samples (39.2%) and 47/180 goose samples (26.1%). Among the 161 isolated Campylobacter spp., 85.7% and 14.3% were Campylobacter jejuni and Campylobacter coli , respectively. Resistance to ciprofloxacin (82.6%), tetracycline (77%) and nalidixic acid (75.2%) was particularly high in the tested Campylobacter isolates. However, all isolates were susceptible to gentamicin, neomycin, streptomycin, neomycin and ampicillin. The presence of Campylobacter spp., as well as the detection of multidrug-resistant isolates in this study, indicates that consuming of duck and goose meat might be a potential campylobacteriosis risk in this region. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the prevalence, characterization and antibiotic resistance of Pasteurella multocida isolated from calves with respiratory infection in Iran. P. multocida was detected in 141/169 bovine respiratory infection cases on Iranian dairy and beef farms. P. multocida were grouped into serogroups A (126/141), D (12/141), and B (3/141). Of the P. multocida isolates, all harboured the psl, ompH, oma87,fimA, ptfA, nartB, and nanH genes, 139/141 had hsf-2, and 115/141 pfhA, and tadD. The isolates were most frequently resistant to penicillin G (43/141 resistant isolates; 30.5%) and streptomycin (31/141; 22%). [ABSTRACT FROM AUTHOR]

In this study, the microstructure, magnetic properties, and tensile behavior of high entropy alloys of FeCoNi(MnAl) x (x = 0–0.6, in molar ratios) were investigated after casting, cold rolling and annealing. X-ray diffractometry (XRD), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM), and also tensile tests were used to evaluate phase formation, microstructure, magnetic behavior and tensile properties of the samples, respectively. The results showed that as the indices of x value increase to 0.6, crystallographic structures transform from FCC to FCC + BCC. This in turn decreased the magnetic saturation of FeCoNi(MnAl) 0.6 from 151 to 36 emu/g. Increasing x to 0.6, also raised the values of Hc from 3 to 16 Oe. This behavior was also observed in annealed and cold rolled alloys. Annealing treatment also released the residual stresses and resulted in reduction of Hc values. However, the highest values of Hc was observed in cold rolled samples which ranged from 5 to 25 Oe. The tensile strength of cold rolled and annealed alloys for x values of 0, 0.2, and 0.4, were 510, 635, and 910 Mpa, respectively. Furthermore, the electrical resistance augmented monotonously with an increasing value of x. It is therefore concluded that cold rolled and annealed high entropy alloys of FeCoNi(AlMn)x can present a variety combinations of tensile, magnetic, and electrical behavior when compared to other soft magnetic materials. • Evaluation of a high entropy alloy of FeCoNi(AlMn) x as rolled and annealed condition were carried out. • Increasing the value of x to 0.6 resulted in changing the crystal structure from FCC to FCC + BCC. • Low Ms, high Hc along with high electrical resistivity was achieved for FeCoNi(AlMn) 0.6. • Increasing the value of x towards 0.6 elevates the strength and reduces ductility. • Cold rolling the alloy increases Hc and annealing the cold-rolled samples decreases the value of Hc. [ABSTRACT FROM AUTHOR]

In this research, zinc sulfide (ZnS) nanostructure powder was successfully synthesized via two-stage annealing (Ar + H 2 S). The annealing under argon medium was responsible for eliminating impurities such as SO 4 , SO 3 and SO 2. The annealing under hydrogen sulfide (H 2 S) medium also led to compensation of sulfur and establishment of Zn to S stoichiometric ratio following sintering. Investigation of different flow rates of H 2 S gas indicated that 30 mL/min would contribute to optimal Zn to S stoichiometric ratio. The Zn to S stoichiometric ratio before sintering under H 2 S medium was 1.28, which increased to 1.55 after annealing under H 2 S medium. The ceramic obtained from ZnS powder annealed under H 2 S medium at 30 mL/min had density of 99.98% and IR transmission of 62% within 8–12 μm range (wavenumbers of 1250–850 cm−1). [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of a single administration of topical povidone-iodine (PVI) 10% plus levofloxacin 0.5% at 1 hour before cataract surgery on perioperative elimination rate of conjunctival flora. Setting: Poostchi Ophthalmology Research Center, Shiraz, Iran. Design: Randomized controlled trial. Method: Patients who required cataract surgery were randomly assigned to 1 of 2 groups: intervention (administration of PVI 10% plus levofloxacin 0.5% at 1 hour preoperatively) or control. The patients in both groups received PVI just before the operation. Conjunctival cultures were obtained using thioglycollate broth at 4 timepoints: T1, before intervention; T2, before the second application of PVI; T3, 3 minutes after the second administration of PVI; and T4, just postoperatively. Results: The study comprised 142 patients. The comparative rates of positive cultures in the intervention vs control groups were as follows: T1 (70.4% vs 73.2%, P =.709); T2 (15.5% vs 71.8%, P <.001); T3 (7.0% vs 19.7%, P =.027); and T4 (5.6% vs 4.2%, P =.698). Coagulase-negative Staphylococci was the most common isolated microorganism. Conclusions: Results showed that a single adjuvant application of PVI 10% plus levofloxacin 0.5% eyedrops at 1 hour before operation leads to a further increase in the rate of sterile conjunctiva just preoperatively. [ABSTRACT FROM AUTHOR]

The aims of this study were to determine the prevalence, characteristics and antimicrobial resistance of Listeria spp. isolated from bovine clinical mastitis in Iran. Listeria spp. were detected in 21/207 bovine mastitic milk samples from dairy farms in Iran, comprising L. monocytogenes (n = 17), L innocua (n = 3) and L. ivanovii (n = 1). L monocytogenes isolates were grouped into serogroups '4b, 4d, 4e', 'l/2a, 3a', '1/ 2b, 3b, 7' and 'l/2c, 3c'; all harboured inlA, inIC and inlj virulence genes. Listeria spp. were most frequently resistant to penicillin G (14/21 isolates, 66.7%) and tetracyclines (11/21 isolates, 52.4%). [ABSTRACT FROM AUTHOR]

The present research has investigated two types of phases (alpha and gamma) of alumina with different sizes (200 nm, 50 nm, and 1000 nm) on the microstructure, transparency, and flexural strength of spark plasma sintered (SPSed) samples. XRD results showed that the powders with a particle size of 1000 nm and 200 nm have a hexagonal crystal system (α- phase), and the nanopowder with a particle size of 50 nm exhibited a cubic lattice (γ phase of alumina). The bulk density of the bulk sample sintered with a particle size of 50 nm, 200 nm, and 1000 nm was 98%, 99%, and 97% of the theoretical density, respectively. The light transmission at sample-200 nm in wavelength of 800 nm was the maximum value (20%), and the other sample-50 nm and -1000 nm obtained 2.5% and 15% light transmission, respectively. IR transmission in the 1000 nm, 200 nm, and 50 nm samples was 15%, 65%, and 25% (at a wavelength of 2.5 µm). The result of bending strength in the sample-200 nm was achieved (133.37 MPa), and this sample is fine-grained and has less porosity compared to the two other samples. [ABSTRACT FROM AUTHOR]

The purpose of this work is to optimize the feed containing alumina‐binder nanoparticles for ceramics injection molding to create transparent alumina parts. In this research, two Alumina with and without MgO as sintering aid fabricated via the spark plasma sintering method. Feed fluidity, fracture toughness, density, IR, and visible transmission of SPSed bodies of the sintered pieces were measured. Furthermore, a pin on the disc test was used on the disk to examine the alumina friction coefficient. The results of feed rheology showed that the sample prepared at 90°C had the best conditions as a pseudoplastic fluid for the ceramic injection molding (CIM) method. The results showed that a combination of CIM and spark plasma sintering (SPS) methods cause more visible transmission than conventional SPS of alumina nanopowder. Also, the fracture toughness and hardness of as‐obtained transparent alumina were in the range of 3.6 MPa m0.5 and 20.1 MPa, respectively. The wear rate of the as‐obtained transparent sample (4.5 × 10−7 mm3/N m) was proportional to the alumina grain size (1–4 μm). [ABSTRACT FROM AUTHOR]

CXC chemokine receptor 4 (CXCR4) has been reported to be involved in organ-specific homing of breast cancer-derived metastasis. We investigated CXCR4 expression by immunohistochemistry as a possible new prognostic factor for primary breast cancer. Two groups of women treated for breast cancer in 1991 at the Centre for the fight against cancer of Upper Normandy—France (Centre de Lutte contre le Cancer de Haute Normandie) were assessed retrospectively. CXCR4 expression was evaluated using standard immunohistochemistry. Usual prognostic factors were recorded in the computer database. Final date of follow-up was December 31, 2001. Tissues were available for 110 node-positive and 84 node-negative breast cancer patients treated in 1991. CXCR4 membrane staining was considered a strong prognostic factor for both 10-year metastasis-free- (p < 0.0001) and overall survival (p < 0.0001) in node-negative but not in node-positive breast cancer patients. CXCR4 cytoplasmic staining was not considered a significant prognostic factor. Our results suggest that CXCR4 membrane staining could be considered a new prognostic factor. Moreover, targeting CXCR4 in primary breast cancer patients may be a new therapeutic concept. However, these results warrant further investigation. [ABSTRACT FROM AUTHOR]

In order to identifying of high yielding compatible sunflower hybrids for different regions of Iran, a set of 10 exotic hybrids from Serbia, Turkey, and Italy and four Iranian hybrids were evaluated for agronomic traits; days to flowering and maturity, plant height, head and stem diameter, 1000-achenes weight, achene number per head, oil content and achene, and oil yield. The experiments were conducted as completely randomized block design with four replications in Alborz, Mazandaran, Khuzestan, and West Azerbaijan Provinces for two years (2017–2018). According to the results growing period of the hybrids were variable from 86 days for Dukat to 98 days for Fantaziya. The hybrids Slatki and Dukat had the highest (70 g) and lowest (56 g) 1000-achenes weight. The highest oil content was observed in 08TR003 (45.6%). Among the locations, Miandoab had the highest achene yield (3110 kg/ha). In Sari; the hybrids Barzegar, Fantaziya, and Slatki (3080, 2893, and 2853 kg/ha respectively), In Dezful; Barzegar, Cartago, and Oscar (3234, 3409, and 3226 kg/ha respectively), in Karaj; Oscar, Shams, and Fantaziya (3138, 3081, and 3050 kg/ha respectively), and in Miandob Shams, Fantaziya, and Slatki (4093, 4038, and 3895 kg/ha respectively) had the highest achene yield. Considering overall mean Fantaziya, Shams, and Oskar had the highest achene yield (3286, 3145, and 3087 kg/ha respectively), as well as Fantaziya followed by Barzegar and Shams had the highest oil yield (1396, 1335, and 1330 kg/ha respectively). Considering phenotypic variability among the exotic hybrids Fantaziya, Oskar, Slatki, Novak, 08TR003, and Meteor with lower coefficient of variation and higher achene yield considered as the stable higher yielding hybrids in four test locations of Iran. Through identifying high-yielding and compatible hybrids, the results of this study can assists in increasing of sunflower yield and production in Iran. [ABSTRACT FROM AUTHOR]

A bond coating of NiCrAlY followed by top coating of Al2O3/YSZ has been applied on an Inconel-718 using an air plasma spraying method, and radiation of a Nd-YAG laser was used to glaze the coated samples. The hot corrosion response of the coatings was measured in 55%V2O5 + 45% Na2SO4 at a temperature of 1000 °C for 3 and 30 h. Leaching of Y2O3 from YSZ, due to the reaction of V2O5 and Na2SO4, was found to be the major reason for the corrosion. Eventually, this led to the formation of YVO4 and tetragonal (t) zirconia to monoclinic (m)-ZrO2 phase transformation. In parallel, the volume fraction of m-ZrO2 in the sprayed coating decreased from 62 to 46%. Reduction of the m-ZrO2 in the glazed coating indicated an improvement of hot corrosion resistance. The results demonstrate that the existence of a dense Al2O3 layer on the upper surface of the sprayed coating led to increased resistance against corrosion. In addition, the laser operation reduced the surface roughness leading to the reduction of the reactive specific surface and the effective contact area between the corrosive materials and the glazed layer. [ABSTRACT FROM AUTHOR]

Highlights • The coatings created by the laser and TIG cladding methods were crack- and pore-free. • The corroded area in the laser cladded sample was thinner than that of the TIG cladded. • The laser cladded samples have a noticeably better hot corrosion resistance than the TIG cladded and the uncoated samples. Abstract The present study investigated the effect of TIG and laser cladding of Inconel 625 coating over an Inconel 738 substrate on its hot corrosion resistance. The hot corrosion test was performed by exposing the specimens to Na 2 SO 4 –60 wt%V 2 O 5 salt at 900 °C for 36 h. Microstructural, elemental, and phase characterization was performed using a field emission scanning electron microscope (FESEM) equipped with an energy dispersive spectrometry (EDS) detector and an X-ray diffractometer (XRD). The microstructural evaluation did not show any crack or pore in the laser-cladded specimen, but revealed a series of cracks at the surface and coating-substrate interface of the TIG-cladded specimen. The phase formed in the coated and uncoated specimens was found to be ϒ-Ni. The results were also indicative of the formation of chromium oxide, nickel oxide, NiCr 2 O 4 spinel, and NiCO 3 after the corrosion test. The corrosion-affected areas in the laser-cladded specimen, TIG-cladded specimen, and uncoated specimen had a thickness of approximately 40 ± 5 μm, 80 ± 10 μm, and 130 ± 10 μm, respectively. The results demonstrated the superior hot corrosion resistance of the laser-cladded specimen, as compared to its TIG-cladded and uncoated counterparts. [ABSTRACT FROM AUTHOR]

Highlights • Improvement of hot corrosion behavior of YSZ–Al 2 O 3 coating by laser glazing. • Similar mechanisms of hot corrosion for both types of coatings. • Reduction of content of m-ZrO 2 fraction from 80% in sprayed to 47% in glazed. • Reduction of roughness from 9.67 to 2.86 µm by laser glazing process. • Reduction of specific reactive surface gained by laser glazing. Abstract The evaluation of hot corrosion behavior of sprayed and laser glazed YSZ + Al 2 O 3 composite coatings was conducted in the presence of 55% V 2 O 5 + 45% Na 2 SO 4 molten salt was conducted. Inconel 718 coupons were sprayed with a Ni–22Cr–10Al–1Y bond-coat and then with an YSZ–Al 2 O 3 top-coat as composite coatings. The sprayed coatings were glazed using a Nd:YAG laser. The results displayed that both coatings illustrated similar mechanisms of hot corrosion. However, the reaction between corrosive molten salt with Y 2 O 3 and production of YVO 4 , leaching Y 2 O 3 from YSZ, led to a destructive phase transformation of tetragonal-ZrO 2 phase (t-ZrO 2) to monoclinic-ZrO 2 phase (m-ZrO 2) and production of YVO 4 , accompanied by 3–5% volume expansion during cooling which could lead to cracking and degradation of TBCs. Findings revealed that by comparing the destabilization fractions of coatings, the content of m-ZrO 2 fraction decreased from 80% in sprayed coating to 47% in laser glazed YSZ + Al 2 O 3 coating, which displayed double improvement of hot corrosion resistance in laser glazing process. Reduction of the reaction between molten salt and zirconia stabilizer was the result of a surface roughness decrease and a specific reactive surface gained by laser glazing process. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study was to investigate the microstructure of the Ni base Inconel 625 coatings that were fabricated on the Inconel 738 substrate with two processes of laser cladding and TIG cladding. For this purpose, single-pass samples were precipitated to obtain optimal parameters. In the laser cladding method, laser power, laser scanning rate and powder feed rate were considered as variables, and current and its type were considered as variables for the TIG method. Based on the results, using the parameters of optimum single-pass samples that were free of porosity, crack and had minor geometric dilution, coatings were applied in both methods with 50% overlap. In order to microstructural, elemental and phasic characterization, field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used. Based on the results, the microstructure of coatings from surface to interface of coating/substrate consists of coaxial, columnar and cellular structure dendrites, respectively, and the laser coating has a finer microstructure due to the higher cooling rate. In addition, the austenite, carbide and Laves phases were observed in both coatings. Highlights • Comparison of microstructure of IN-625 coatings applied to IN-738 by laser and TIG cladding methods for the first time. • The coatings created by the laser-cladding and TIG cladding techniques were crack and pore free. • The microstructure of the coating created by laser cladding is finer than that created by TIG due to the higher cooling rate. [ABSTRACT FROM AUTHOR]

In this research, germanium-carbon coatings were deposited on ZnS and glass substrates by a RF plasma enhanced chemical vapor deposition method using GeH and CH as precursors. ZnS/GeC double-layer antireflection coating with optical thickness of one quarter wavelength was designed. The samples were characterized by fourier transform infrared spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy and nanoindentation. The coatings exhibited a structure free of pores with a very good adhesion to substrate. Based on the XRD patterns, no diffraction peak was found, so all the coatings mainly had an amorphous structure. The infrared (IR) transmittance spectrum show that the maximum IR transmittance in the band of 1030-1330 cm was about 84.6%, which is higher than ZnS substrate by 10%. In addition, the reflection of ZnS substrate is about 25%. This system has reduced the reflection from the substrate by 15%. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to determine intraocular pressure (IOP) and central corneal thickness (CCT) measurements in healthy Persian children to find clinical reference values in this ethnicity. Additionally, we examined the possible relationship between these measurements. Methods: This cross-sectional study included 262 eyes of 131 Persian primary school children between 6 and 13 years of age. All eyes were healthy and had no anterior or posterior segment abnormalities, corneal disease, or evidence of glaucoma. Specular microscopy was used to measure CCT and both noncontact tonometry (NCT) and Goldmann applanation tonometer (GAT) were used to measure IOP. Correlations between IOP measurements were also examined. Results: Mean CCT was 513.47 ± 34.51 μm in the right eye (OD) and 513.93 ± 33.88 μm in the left eye (OS). The CCT was not significantly different between older (10-13 years) and younger (6-9 years) patients. Mean IOP measured with GAT was 13.86 ± 2.13 mmHg OD and 13.72 ± 2.04 mmHg OS and mean IOP measured with NCT was 15.26 ± 2.38 mmHg OD and 15.11 ± 2.18 mmHg OS. The IOP and CCT measured with GAT were weakly correlated (OD: r = 0.141, P = 0.114; OS: r = 0.236, P = 0.007). However, IOP and CCT measured with NCT (OD: r = 0.487, P = 0.000; OS: r = 0.456, P = 0.000) were moderately correlated. Our outcomes demonstrated that for 100 μm increase in CCT, IOP measured with GAT and NCT increased by 0.8 and 3.3 mmHg, respectively, in OD and by 1.4 and 2.9 mmHg in OS. Based on intraclass correlation coefficients, IOP measurements made with GAT and NCT were in fair agreement in OD and in good agreement in OS. Conclusion: The IOP and CCT in healthy Persian school children (6-13 years old) were positively correlated. Our findings revealed that corneal thickness is thinner in Persian children than in most other racial groups. Funding: This study has been funded by deputy dean in research of School of Medicine and deputy vice chancellor of Shiraz University of Medical Sciences, Shiraz, Iran. [ABSTRACT FROM AUTHOR]

A novel strain was isolated from an agricultural soil in Malaysia. After morphological and genetic characterization, the novel strain showed the highest similarity to Bacillus species. The ability of biostimulation (waste tealeaf) and bioaugmentation (Bacillus salmalaya 139SI) activities was investigated on soil polluted with 6% (w/w) waste crude oil for duration of 60 days. Strain 139SI was able to decrease the surface tension to 35 mN/m. Degradation of the initial petroleum hydrocarbon by 70% was achieved in the treatments involving B. salmalaya strain 139SI and tealeaf compared to the sterilized polluted soil (15%), which served as a control for this study. The aerobic utilizing bacteria counts and dehydrogenase activity were significantly increased during the period of study. Analysis of residual waste crude oil monitored by gas chromatography spectrophotometer indicated 80-95% degradation of n-C8 to C12 followed by a 40% removal ratio of C22. Kinetic model showed that treatment amended with both tealeaf and strain has indicated the highest level of biodegradation rate, with rate constant of 0.107 day-1, while the biodegradation rate was 0.08 day-1 in treatments amended with only tealeaf. The finding showed the potentiality of tealeaf and Bacillus salmalaya 139SI toward the degradation/decomposition of crude oil in contaminated soil. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of laser glazing on the hot corrosion behavior of nanostructured thermal barrier coatings (TBCs) was investigated. To this end, the hot corrosion test of plasma-sprayed and laser-glazed thermal barrier coatings conducted against 45wt.% Na2SO4 +55wt.% V2O5 molten salt at 910°C for 30h in open air atmosphere. The results obtained from hot corrosion test showed that the reaction between Y2O3 and the corrosive salt produced YVO4, leached Y2O3 from YSZ and led to the progressive destabilization transformation of YSZ from tetragonal to the monoclinic phase. The lifetimes of the plasma-sprayed TBCs were enhanced approximately twofold by laser glazing. Reducing the reactive specific surface area of the dense glazed layer with the molten salts and improving the stress accommodation through network cracks produced by laser glazing were the main enhancement mechanisms accounting for TBC life extension. [Copyright &y& Elsevier]

Highlights: [•] Surface of plasma sprayed CYSZ TBCs modified by a pulsed Nd:YAG laser. [•] A dense glazed layer produced on the surface of TBCs by laser treatment. [•] The specific reaction area was reduced after laser glazing. [•] The hot corrosion resistance of TBCs was enhanced more than twofold by laser surface glazing. [Copyright &y& Elsevier]

The suspensions of nanosized YSZ powder with different binder (polyvinyl alcohol, PVA) contents were agglomerated into plasma sprayable feedstocks. The agglomeration was performed by the spray drying method. Two types of morphologies (spherical and non-spherical) were obtained after spray drying of the ball milled and non-ball milled nanopowders. The suitable granules size distributions (25–150µm, average size=45±3µm) with good apparent density (before calcination treatment=800kg/m3 and after calcination=900kg/m3) and flowability (before calcination=0.31g/s and after calcination=0.41g/s) for plasma spraying were obtained with 5wt% PVA and calcination temperature up to 800°C. Finally, the correlation between the granules shape and the resulting coating porosity and thermal insulation capability was investigated. [ABSTRACT FROM AUTHOR]

Abstract: Nanostructured scandia (4.6mol%), yttria (0.4mol%) doped zirconia (5SYSZ) and 7wt% yttria stabilized zirconia (7YSZ) thermal barrier coatings (TBCs) were produced by plasma spraying on nickel-based superalloy substrates with NiCrAlY as the bond coat. The thermal shock behavior of the two as-sprayed TBCs at 1000°C was investigated. The results indicated that the thermal cycling lifetime of 7YSZ TBCs was longer than the 5SYSZ TBCs due to the lower thermal mismatch stress between the ceramic layer and the metallic layer at high temperature. However, the nanostructured 5SYSZ coating had higher thermal stability than 7YSZ TBC. [Copyright &y& Elsevier]

Abstract: The main goal of this paper was to evaluate the effects of laser glazing on the microstructure and thermal shock resistance of nanostructured thermal barrier coatings (TBCs). To this end, nanostructured yttria stabilized zirconia (YSZ) top coat and NiCrAlY bond coat were deposited on Inconel 738LC substrate by air plasma spraying (APS). The Nd:YAG pulsed laser was used for laser treatment of top coat surface. The thermal shock behavior of plasma-sprayed and laser-glazed coatings was investigated by quenching the samples in cold water from 1000°C. The microstructure and phase composition of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Energy dispersive spectroscopy (EDS) was used to analyze the interface diffusion behavior of the bond coat elements. The results of SEM revealed that the laser glazing process reduced the surface roughness, eliminated the porosity of the surface and produced network cracks perpendicular to the surface. XRD results also indicated that both as-sprayed and laser glazed coatings consisted of non-transformable (T′) phase. Thermal shock test results showed that the lifetimes of the plasma-sprayed TBCs were almost doubled by laser glazing. Continuous network of segmented cracks perpendicular to the surface produced by laser glazing improved the strain accommodation and recognized it as the main enhancement mechanism for TBC life extension. [Copyright &y& Elsevier]

Abstract: This study addresses the correlation between the feedstock agglomerates with their resulting coating microstructure and thermal insulation capability. To this end, the Y2O3 and Sc2O3 codoped in ZrO2 (SYSZ) nanopowders were synthesized by the polymeric sol–gel method, their suspensions were agglomerated into plasma sprayable feedstock by the spray drying method, and finally, the effect of feedstock morphology on the microstructures and thermal insulation capability of APS coatings was investigated. The coating microstructure consisted of semi-molten feedstock agglomerates surrounded by fully molten particles that acted as binders. Solid irregular SYSZ granules yielded coatings with lower porosity and thermal insulation capability than the porous spherical YSZ ones. [Copyright &y& Elsevier]

Abstract: Nanostructured thermal barrier coatings (TBCs) consisting of yttria stabilized zirconia (YSZ) ceramic top coat and NiCrAlY metallic bond coat were prepared by atmospheric plasma spraying (APS). The Nd:YAG pulsed laser was used for laser treatment of top coat surface. The microstructure and thermal insulation capability of plasma-sprayed and laser-glazed thermal barrier coatings were investigated. The microstructure and phase composition of the coating were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD). The nanostructured plasma-sprayed coating contained non-melted or partially melted nanosized particles and columnar grains, whereas the microstructure of laser-glazed coating consisted of columnar grains in the fracture surface and equiaxed grains on the surface. Laser glazing, which helps to eliminate the surface porosities and other structural defects of coatings deposited by the plasma spraying method, should contribute to the improvement of their surface roughness. XRD results revealed that both as-sprayed and laser-glazed coatings consisted of non-transformable tetragonal (T′) phase. The results of the thermal insulation capability test indicated that the thermal insulation capability of the laser-glazed coating, as compared to the as-sprayed coating, was slightly lower due to the microstructural change in the glazed layer of top coat. [Copyright &y& Elsevier]

Abstract: The main goal of this paper was to evaluate and compare the microstructure and mechanical properties of plasma-sprayed nanostructured and conventional yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). To this end, NiCrAlY bond coat, nanostructured, and conventional YSZ coatings were deposited on Inconel 738LC substrate by atmospheric plasma spraying (APS). The mechanical properties of the coating were evaluated using nanoindentation and bonding strength tests. The microstructure and phase composition of the coating were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD). The nanostructured YSZ coating contained both nanosized particles retained from the powder and microcolumnar grains formed through the resolidification of the molten part of the powder, whereas the microstructure of the conventional YSZ coating consisted of columnar grain splats only. The phase composition of the as-sprayed nanostructured coating consisted of the non-transformable tetragonal phase, while the conventional coating showed the presence of both the monoclinic and non-transformable tetragonal phases. The results of nanoindentation and bonding strength tests indicated that the mechanical properties of the nanostructured coating were better than those of the conventional coating. [Copyright &y& Elsevier]

Abstract: In this study, Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bond coat and then with a ceria and yttria stabilized zirconia (CYSZ) top coat by air plasma spraying (APS). After that, the plasma sprayed CYSZ thermal barrier coatings (TBCs) were treated using a Nd:YAG pulsed laser. The effect of laser glazing on the microstructure of the coatings was investigated. The microstructures and surface topographies of both as-sprayed and laser glazed samples were investigated using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The phases of the coatings were analyzed with X-ray diffractometry (XRD). The microstructural analysis results revealed that laser surface glazing of ceramic top coat reduced the surface roughness considerably, eliminated the surface porosities and produced a network of continuous cracks perpendicular to the surface. XRD patterns also showed that both as-sprayed and laser glazed top coats consisted of nonequibrium tetragonal (T′) phase. [Copyright &y& Elsevier]

Abstract: In this study, substrates of Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bondcoat and then with a ceria and yttria stabilized zirconia (CYSZ; ZrO2−25wt%CeO2−2.5wt%Y2O3) topcoat by air plasma spraying (APS). Hot corrosion studies of plasma sprayed thermal barrier coatings (TBCs) were conducted in 45wt%Na2SO4+55wt%V2O5 molten salt at 1000°C for 30h. The results showed that the coating defects, such as pores and microcracks play important roles as effective paths for the salt penetration in hot corrosion. Based on the results, the reaction between molten salt and stabilizers of zirconia (Y2O3 and CeO2), the formation of YVO4, CeVO4 and CeO2 crystals, the detrimental phase transformation of zirconia from tetragonal to monoclinic due to the depletion of stabilizers and finally, the creation of stresses were recognized to be in the degradation mechanism of CYSZ ceramic coatings in the presence of molten sulfate–vanadate salt. [Copyright &y& Elsevier]

Abstract: In this study, substrates of Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bondcoat and then with a ceria and yttria stabilized zirconia (CYSZ) topcoat by air plasma spraying (APS). After that, the plasma sprayed CYSZ thermal barrier coatings (TBCs) were treated using a pulsed Nd:YAG laser. The effects of laser glazing on the microstructure and thermal shock resistance of the coatings were evaluated. Thermal shock test was administered by holding specimens at 950°C for 5min and then water quenching. More than 20% of the spalled region of the surface of the topcoat was adopted as the criterion for the failure of samples. The microstructures of both the as processed and the tested TBCs were investigated using scanning electron microscope (SEM). The phases of the coatings were analyzed with X-ray diffractometry (XRD). XRD analysis revealed that both as sprayed and laser glazed topcoats consisted of nonequilibrium tetragonal (T′) phase. The results showed that the life times of the as sprayed TBCs were enhanced around fourfold by the formation of a continuous network of segmented cracks perpendicular to the surface and the increase in strain accommodation. [Copyright &y& Elsevier]