Search

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]

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]

The rapid progress of electronic and communication systems within the gigahertz range has led to problems including interference and contamination of electromagnetic (EM) waves. The design and fabrication of new as well as economical EM wave absorbents for resolving these problems have attracted the attention of researchers. This work has inspected the electromagnetic and mechanical action of Lightweight and pliable cellulose—multi-walled carbon nanotubes (MWCNTs)- strontium ferrite (SrFe12O19) aerogel composite in the X-band range. The Effect of MWCNT to SrFe12O19 weight ratio on the magnetic and EM wave behavior of cellulose/MWCNTs/SrFe12O19 aerogel was investigated. The results revealed that in the sample containing 10 wt.% MWCNTs and 5 wt.% SrFe12O19 nanoparticles, the shielding value of microwaves within the X- band range reached more than 40 dB. Also, in this sample, the effective absorption threshold was found at thicknesses larger than 1.5 cm. The best absorption bandwidth (8.2–12.4 GHz) was observed in the thickness of 3 cm. [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]

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]

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]

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]

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]

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]

Purpose: The study aimed to review the indications and techniques for corneal transplantation at a tertiary referral center over a 5-year period. Methods: Records of patients who underwent corneal transplantation at Khalili Medical Center, Shiraz, Iran from September, 2012 to September, 2017 were reviewed. Results: A total of 1149 eyes of 956 patients underwent corneal transplantation. The most common indication was infectious corneal ulcers (n = 296, 25.8%), followed by keratoconus (n = 243, 21.1%), bullous keratopathy (n = 219, 19.1%), failed grafts (n = 117, 10.2%), non-herpetic corneal scars (n = 113, 9.8%), corneal stromal dystrophies (n = 33, 2.9%), pellucid marginal degeneration (n = 31, 2.7%), and trauma (n = 26, 2.3%); other indications included thin descemetocele, post-herpetic corneal scar, endothelial corneal dystrophies, anterior segment dysgenesis, corneal ectasia after laser in situ keratomileusis, and corneal fibrosis. Corneal transplantation techniques included penetrating keratoplasty (PKP, n = 789, 68.7%), deep anterior lamellar keratoplasty (DALK, n = 187, 16.3%), Descemet's stripping automated endothelial keratoplasty (n = 171, 14.9%), and keratolimbal allograft (n = 2, 0.1%) in descending order. In children (aged ≤18 years), the most common indication was keratoconus (n = 32, 41.6%), and the most common technique was PKP (n = 50, 64.9%). In patients aged 19-27 years, the most common indication was keratoconus (n = 89, 64.5%), and the most common technique was PKP (n = 75, 54.4%). Conclusion: Infectious corneal ulcer was the most common indication, and PKP was the most prevalent technique in patients undergoing corneal transplantation. DALK was an emerging alternative surgical treatment in patients with corneal disorders in which corneal endothelium is spared. [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]

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]