Substrate induced proximity effect in superconducting niobium nanofilms

Structural and superconducting properties of high quality Niobium nanofilms with different thicknesses are investigated on silicon oxide and sapphire substrates. The role played by the different substrates and the superconducting properties of the Nb films are discussed based on the defectivity of the films and on the presence of an interfacial oxide layer between the Nb film and the substrate. The X-ray absorption spectroscopy is employed to uncover the structure of the interfacial layer. We show that this interfacial layer leads to a strong proximity effect, specially in films deposited on a SiO$_2$ substrate, altering the superconducting properties of the Nb films. Our results establish that the critical temperature is determined by an interplay between quantum-size effects, due to the reduction of the Nb film thicknesses, and proximity effects

Electromagnetic fluctuation-induced interactions in randomly charged slabs

Randomly charged net-neutral dielectric slabs are shown to interact across a featureless dielectric continuum with long-range electrostatic forces that scale with the statistical variance of their quenched random charge distribution and inversely with the distance between their bounding surfaces. By accounting for the whole spectrum of electromagnetic field fluctuations, we show that this long-range disorder-generated interaction extends well into the retarded regime where higher-order Matsubara frequencies contribute significantly. This occurs even for highly clean samples with only a trace amount of charge disorder and shows that disorder effects can be important down to the nano scale. As a result, the previously predicted non-monotonic behavior for the total force between dissimilar slabs as a function of their separation distance is substantially modified by higher-order contributions, and in almost all cases of interest, we find that the equilibrium inter-surface separation is shifted to substantially larger values compared to predictions based solely on the zero-frequency component. This suggests that the ensuing non-monotonic interaction is more easily amenable to experimental detection. The presence of charge disorder in the intervening dielectric medium between the two slabs is shown to lead to an additional force that can be repulsive or attractive depending on the system parameters and can, for instance, wash out the non-monotonic behavior of the total force when the intervening slab contains a sufficiently large amount of disorder charges.Comment: 9 pages, 5 figure

Dimensional crossover and incipient quantum size effects in superconducting niobium nanofilms

Superconducting and normal state properties of sputtered Niobium nanofilms have been systematically investigated, as a function of film thickness in a d=9-90 nm range, on different substrates. The width of the superconducting-to-normal transition for all films remained in few tens of mK, thus remarkably narrow, confirming their high quality. We found that the superconducting critical current density exhibits a pronounced maximum, three times larger than its bulk value, for film thickness around 25 nm, marking the 3D-to-2D crossover. The extracted magnetic penetration depth shows a sizeable enhancement for the thinnest films, aside the usual demagnetization effects. Additional amplification effects of the superconducting properties have been obtained in the case of sapphire substrates or squeezing the lateral size of the nanofilms. For thickness close to 20 nm we also measured a doubled perpendicular critical magnetic field compared to its saturation value for d>33 nm, indicating shortening of the correlation length and the formation of small Cooper pairs in the condensate. Our data analysis evidences an exciting interplay between quantum-size and proximity effects together with strong-coupling effects and importance of disorder in the thinnest films, locating the ones with optimally enhanced critical properties close to the BCS-BEC crossover regime

Molecular evaluation of the population of Silver Pomfret (Pampus argenteus) in the Persian Gulf and Oman Sea (Iranian &Kuwaiti waters)

A total of 162 specimens of Silver Pomfret (Pampus argenteus) including 38 samples from Kuwait and 124 samples from Iran (24 from Khouzestan, 24 from Chabahar and 38 from Bushehr) were examined for their DNA structure. DNA from all specimens was extracted using the Phenol-chloroform and amplified using PCR method with a pair of primers with ND sub(2) gene sequence. The PCR products were about 1300 (bp) for all samples. For RFLP analysis 16 restriction enzymes Bcl I, Pst I, Acc II, BseN I, Tru I, Dra I, Alw26 I, Hin6 I, Tas I, Alu I, EcoR I ,Hae III, Hinc II, Hind III, Hinf I and Hpa II were used. DNA bands were visualized by Gel electrophoresis (polyacrylamid) and staining with silver nitrate. Out of 16 enzymes, four showed polymorphism that includedg Hinf I, Alu I, Acc II, and Hpa II. Of the total 162 samples, 13 showed polymorphic patterns. Six haplotypes were rare occurring only once, but others which were only four different kinds occurred more than once. The REAP test gave no significant result for the examined regions (P>0.05). Therefore, our results revealed that the Pampus argenteus stocks in the Persian Gulf and Oman Sea of Iranian and Kuwaiti waters constitute a unique population

Chromogenic in situ hybridisation test for breast cancer patients with equivocal IHC results - A study from Iran

Background: HER2/neu overexpression on cell membranes of breast cancer cells is due to HER2/neu gene amplification and it is important to identify potential candidates for anti HER2 therapy with trastuzumab. IHC, FISH and CISH are standard FDA approved assays currently used to determine HER2 status in routine practice. The aim of this study was to determine HER2 gene amplification, using the CISH method in breast carcinoma samples which had IHC +2 reactions. Materials and Methods: This study was conducted from 2008-2010 using 334 consecutive breast carcinoma samples referred from local laboratories to Mehr Hospital. CISH assays were performed for all cases, and IHC tests were also done for determining efficacy and accuracy of local labs. HER2 status in local IHC tests was compared with central IHC and CISH results. Results: Of 334 breast cancer patients, 16 were negative for HER2 IHC (0, +1), 201 cases were equivocal (+2), and 31 positive (+3). Of 334 referral cases, 88 were CISH positive (26.3) and 246 were CISH negative (73.7). Of 201 IHC +2 cases, HER2 gene amplification was observed in 42 cases (kappa: 0.42). A 29.9 concordance was found between local IHC and central IHC. Sensitivity and specificity of local IHC were 90 and 53.8, respectively. Conclusions: Low accuracy of IHC results in local labs was associated with the following factors: using former FDA-approved criteria for HER2 interpretation, utilizing non-validated kits, and lack of any quality assurance program. Therefore, following the new 2014 ASCO/CAP guideline and comprehensive quality assurance should be implemented to ensure accuracy of HER2 testing

Population genetic study on two commercial shrimp species and determining of DNA-Barcoding of 6 – 8 species by partial sequencing of mtDNA using molecular method (PCR-Sequencing)

Barcodes are short segments of DNA that can be used to uniquely identify an unknown specimen to species, particularly when diagnostic morphological features are absent. These sequences could offer a new forensic tool in plant and animal conservation especially for endangered species. Ideally, barcodes could be used to positively identify illegally obtained material even in cases where diagnostic features have been purposefully removed or to release confiscated organisms into the proper breeding population. In the present study molecular data were used besides the morphological ones to introduce a specific barcode for six selected species of Shrimp. Based on the previous phylogenetics study, it has been proved that the mitochondrial COI gene in crustacean is a good discriminative marker at both inter- and intra-specific levels. In this regard, six species of shrimp (Fenoro penaeus indicus, Fenoro penaeus merguensis, penaeus semisulcatus, Metapenaeus affinis, Marsupenaeus japonicas, Fenoro penaeus penicillatus were collected from the Persian Gulf and Oman sea. After identification, the total DNA was extracted; COI gene was first amplified and then sequenced for each species. Finally the collected data were analyzed with the specific phylogenetic software. Molecular analysis revealed some degree of interpopulation differences but six good species were recognizable based on COI sequences. Also for population study molecular data of two species Penaeus semisulcatus and Metapenaeus affinis were analysed base on COI RFLP and 16SrRNA sequences respectively. The results would be helpful to protect shrimp species

Examining the effects of platelet-rich plasma and platelet-rich fibrin on autologous full thickness skin graft survival in rats

Background: Graft survival has been considered the major problem in reconstructive surgery. Clinical studies have helped us to understand the role of PRP in increasing skin survival. Our goal in this study was to examine the treatment effects of platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) on autologous full thickness skin graft survival in male rats. Methods: This experimental study was performed on 36 rats of Sprague-Dawley race with weighing approximately 250 to 300 gr on May 2015 in animal laboratory of Hazrat Fatima Hospital. After anesthesia, rats were divided into 3 groups. We injected platelet-rich plasma (PRP) in the first group, platelet-rich fibrin (PRF) in the second and saline in the third group after removing the skin. Microscopic analysis was performed with camera (Canon powershot SX200, Tokyo, Japan) on days 7, 14, 21 and 28 after surgery. We used image analysis system (ImageJ, ver. 1.45) to examine necrosis and survival rate. Samples were studied with H&E staining on day 28 microscopically for histological analysis of vascular density and angiogenesis. Results: Our findings showed the area of necrosis in animals injected with PRP on days 7 and 14, was meaningfully less than control group (P= 0.0001). There was no meaningful difference between control and PRP groups (P> 0.05). The area of necrosis in animals injected with PRF did not have any significant difference with control group from beginning to 21st day (P< 0.0001). there was no meaningful difference in vascular density between control and PRP group, whereas in animals injected with PRF the vascular density was significantly less than control group (P= 0.002). Conclusion: According to our results in this study, we can conclude that using autologous PRP can enhance the process of healing soft tissue injury and be affective at increasing graft survival. This method is suggested to be conducted for patients highly at risk of graft loss and also for those who are in need of early treatments. © 2016, Tehran University of Medical Sciences. All rights reserved

Sensitive high-resolution melting analysis for screening of kras and braf mutations in Iranian human metastatic colorectal cancers

Background: Investigations of methods for detection of mutations have uncovered major weaknesses of direct sequencing and pyrosequencing, with their high costs and low sensitivity in screening for both known and unknown mutations. High resolution melting (HRM) analysis is an alternative tool for the rapid detection of mutations. Here we describe the accuracy of HRM in screening for KRAS and BRAF mutations in metastatic colorectal cancer (mCRCs) samples. Materials and Methods: A total of 1000 mCRC patients in Mehr Hospital, Tehran, Iran, from Feb 2008 to May 2012 were examined for KRAS mutations and 242 of them were selected for further assessment of BRAF mutations by HRM analysis. In order to calculate the sensitivity and specificity, HRM results were checked by pyrosequencing as the golden standard and Dxs Therascreen as a further method. Results: In the total of 1,000 participants, there were 664 (66.4) with wild type and 336 (33.6) with mutant codons 12 and/or 13 of the KRAS gene. Among 242 samples randomly checked for the BRAF gene, all were wild type by HRM. Pyrosequencing and Dxs Therascreen results were in line with those of the HRM. In this regard, the sensitivity and specificity of HRM were evaluated as 100. Conclusion: The findings suggest that the HRM, in comparison with DNA sequencing, is a more appropriate method for precise scanning of KRAS and BRAF mutations. It is also possible to state that HRM may be an attractive technique for the detection of known or unknown somatic mutations in other genes