90 research outputs found
Comparison of chilling and heat requirement in some peach and apricot cultivars
Bud Dormancy in deciduous fruit trees of the temperate zones is a phase ofdevelopment that occurs annually and enables trees to survive cold winters. Chilling andheat requirements for breaking dormancy and flowering were studied in five peach (Kosary,Haj Kazemi, Anjiry Asali, Anjiry Zafarany, and Zoud Ras) and four apricot (asgarabad,shamlo, shakarpare, tabarze ghermez) cultivars. Various models (two chilling hour models,the <7C and 0-7C models, and two chilling unit models, the Utah and Low Chill) were usedto measure the accumulation of chilling requirement. The heat requirements were calculatedas the growing degree hours (GDH) accumulated from breaking of dormancy to the F50 (50%of opened flowers). The cultivars studied showed a range of chilling requirements (chillunits, CU), between 746 to 868 CU for peach and 652-826 CU for apricot. The heatrequirements for peaches and apricots were between (4099 to 4543GDH) and (2987 to3465GDH) respectively. Apricot cultivars with lower chilling and heat requirements showedearlier flowering dates. Thus apricot cultivars bloomed between 15 and 16 day before peachcultivars and Heat requirements were found to be more important for regulation offlowering time than were chilling requirement in our climatic condition
the effect of residual stress on fatigue behavior of v notched components a review
Abstract: Fatigue strength of mechanical components in the high cycle regime depends on the intensity of the residual stress field induced by non-homogeneous plastic deformation or the solidification of a local portion of material due to welding operations. In presence of geometric variations modelled as sharp V-notch angle, the residual stress distribution near the notch tip is singular and follows the same solution obtained by Williams in 1952 where the intensity of the asymptotic stress field is quantified by the notch stress intensity factor (NSIF). However, the residual stress varies during fatigue loading until a stationary value is reached. Numerical models were developed for the calculation of the residual NSIFs and their variation under fatigue loading. Taking advantage from these models, new approaches were recently developed which are able to predict the fatigue strength of pre-stressed notched components. A review of such recent advances is described in this work
Experimental and numerical investigations of fracture behavior of magnetostrictive materials
Abstract: The purpose of this work is the characterization of the fracture behaviour of giant magnetostrictive materials subjected to a magnetic field. Both experimental and numerical investigations have been performed, focusing on iron and rare earth alloys, such as the commercially named Terfenol-D. Tests have been carried out on single-edge precracked specimens subjected to three-point bending in the presence of magnetic fields of various intensities and fracture loads have been measured at different loading rates. Recent studies on local stress fields in proximity of crack and notch tips have shown that Strain Energy Density (SED), averaged in a circular control volume which includes a crack tip, could be a robust parameter in the assessment of brittle fracture resistance of several materials. Coupled-field analyses have then been performed on both plane stress and plane strain finite element models and the effect of the magnetic field on fracture resistance of Terfenol-D alloy was predicted in terms of averaged SED. A relationship between the SED's control volume size and the loading rate has also been proposed
some recent criteria for brittle fracture prediction under in plane shear loading
Abstract: Different criteria are available in the literature to assess the fracture behaviour of sharp V-notches. A typical and well-known criterion is based on the application of the notch stress intensity factors (NSIFs), which are able to quantify the intensity of the stress fields ahead of the notch tip. This work considers two recent energy-based criteria applied here to sharp V-notches. The first criterion is based on the averaged value of the strain energy density (SED), while the second one called Finite Fracture Mechanics (FFM) criterion is available under two different formulations: that by Leguillon et al. and that by Carpinteri et al. Considering the averaged SED criterion, a new expression for estimating the control radius R c under pure Mode II loading is proposed and compared with the sound expression valid under pure Mode I loading. With reference to pure Mode II loading the critical NSIF at failure can be expressed as a function of the V-notch opening angle. By adopting the three criteria considered here the expressions for the NSIFs are derived and compared. After all, the approaches are employed considering sharp V-notched brittle components under in-plane shear loading, in order to investigate the capability of each approach for the fracture assessment. With this aim a bulk of experimental data taken from the literature is used for the comparison
Screening and evaluation of indigenous bacteria from the Persian Gulf as a probiotic and biocontrol agent against Vibrio harveyi in Litopenaeus vannamei post larvae
Isolation of autochthonous bacteria from marine sources as a potential probiont in biocontrolling against pathogenic Vibrio species in the shrimp culture industry was the aim of current research. A total of 198 bacterial strains were isolated from pond water, sediment, hepatopancreas and gut samples of shrimps after culturing the samples on Tryptic Soy Agar and incubated at 30 °C for 24-48 h. The isolates were tested for their antagonistic activity in contact with Vibrio harveyi. Two strains (IS02 and IS03) that isolated from the gut and pond sediment were showed antagonistic against V. harveyi. According to 16S ribosomal DNA gene sequence analysis, the strain IS02 was identified as Bacillus subtilis and IS03 as B. vallismortis. Further, the two bacterial species, B. subtilis and B. vallismortis were challenged separately for probiotic activity in the post larvae of Litopenaeus vannamei against pathogenic V. harveyi. The present study identified B. subtilis IS02 and B. vallismortis IS03 had biocontrol activity against V. harveyi in vitro and in vivo and they increase growth performance of L. vannamei in post larvae stage
Autophagy in cancers including brain tumors: role of MicroRNAs
Autophagy has a crucial role in many cancers, including brain tumors. Several types of endogenous molecules (e.g. microRNAs, AKT, PTEN, p53, EGFR, and NF1) can modulate the process of autophagy. Recently miRNAs (small non-coding RNAs) have been found to play a vital role in the regulation of different cellular and molecular processes, such as autophagy. Deregulation of these molecules is associated with the development and progression of different pathological conditions, including brain tumors. It was found that miRNAs are epigenetic regulators, which influence the level of proteins coded by the targeted mRNAs with any modification of the genetic sequences. It has been revealed that various miRNAs (e.g., miR-7-1-3p, miR-340, miR-17, miR-30a, miR-224-3p, and miR-93), as epigenetic regulators, can modulate autophagy pathways within brain tumors. A deeper understanding of the underlying molecular targets of miRNAs, and their function in autophagy pathways could contribute to the development of new treatment methods for patients with brain tumors. In this review, we summarize the various miRNAs, which are involved in regulating autophagy in brain tumors. Moreover, we highlight the role of miRNAs in autophagy-related pathways in different cancers. Video abstract
Isolation, identification and characterization of new luminous bacteria from Chah Bahar Port, southern marine habitat of Iran
Coastal region of Chah Bahar port, Sea of Oman, was screened for the presence of bioluminescence bacteria for the first time. Water samples were taken from surface and subsurface layers and immediately spread on nutrient seawater complete (SWC) agar. Luminous colonies were observed after an overnight incubation at 25°C. Among twenty luminous isolates, four of them were selected for preliminary bacterial identification based on morphological and physiological characteristics. 16S rRNA genes of selected bacteria were then sequenced in order to be submitted in GenBank database as new strains and performing phylogenetic analysis. Four different submitted bacterial strains are as follow, Vibrio sp. Persian 1, Vibrio sp. Persian 2, Vibrio sp. Persian 3, and Vibrio sp. Persian 4 with accession numbers of KC505639, KC765088, KC765089, and KC896417, respectively. Light emission of isolated luminous bacteria was measured using luminometer. Vibrio sp. Persian 1 was found as the best light emitter with counts per second/OD 600 nm equal to 10 × 10^6 RLU/Sec/OD. Isolated Vibrio species were tested for their ability to form biofilm. Vibrio sp. Persian 3 showed weak ability to produce biofilm while other species were considered as moderate biofilm producers
A double-blind, randomized comparison study between Zytux� vs MabThera® in treatment of CLL with FCR regimen: Non-inferiority clinical trial
Background: Chronic lymphocytic leukemia (CLL) is characterized by accumulation of B cells in blood, lymphoid tissues and bone marrow. Addition of rituximab to CLL chemotherapy regimens has been associated with improved survival. The aim of this study was to establish efficacy and safety of Zytux� in comparison to MabThera® in treatment of CLL. Materials and Methods: Seventy CLL patients who met the criteria for entering the study were randomized into two groups (35 patients in each group). Both groups received Fludarabine and Cyclophosphamide plus Rituximab as part of the FCR regimen. Group A was treated with Zytux�, and group B was treated with MabThera®. A non-inferiority margin of 20 for the primary outcome was defined to examine the similarity between Zytux� and MabThera®. Results: Baseline demographic characteristics showed no statistically significant difference between the two groups. The two treatment groups were comparable in terms of laboratory and clinical findings, cellular index changes and CD (5, 19, 20 and 23) counts during therapy cycles and at the end of the treatment period. Regarding safety results, Zytux� demonstrated a similar profile of adverse reactions in comparison to MabThera®. Moreover, the overall response rate was 88 and 89 for Zytux� and MabThera®, respectively (CI -0.17, 0.18). Conclusion: Results showed non-inferiority of Zytux� in terms of efficacy and adverse events as a biosimilar version of MabThera®. © 2018, Tehran University of Medical Sciences (TUMS). All rights reserved
Comprehension of complex sentences in the Persian-speaking patients with aphasia
Introduction: To study sentence comprehension in Persian-speaking Patients with Aphasia considering the factors of complexity. Methods: In this cross-sectional study, the performance of 6 non-fluent aphasic patients were tested and their performance was compared to 15 matched control group. Comprehension of semantically reversible sentences was assessed using a binary sentence-picture matching task. The stimuli were as follows: clefts; subject clefts and object clefts, also relative clauses; subject relatives and object relatives. All of them were types of movement-derived structures and also simple declarative sentences as the control task. Results: The best performance of aphasic patients were seen in the comprehension of subject clefts, although prior to this result we assumed that simple declarative sentences (in which there is no structural factor of complexity) can be understood easily. They showed the highest difficulty in the comprehension of object relatives. Furthermore, the performance of patients in the comprehension of relative clauses was significantly weaker than understanding the clefts. Conclusion: The outcomes of this study suggest that the sentence comprehension deficits of aphasic patients, in contrast to the specific deficit models, may not be related to linguistic disabilities. Moreover, the problems in the comprehension of non-canonical sentences may be related to failure in the allocation of attention. Finally, our results support the claims that neural characterization of the cognitive resources (e.g. working memory) is disrupted in sentence comprehension deficits. © 2019 Iran University of Medical Sciences. All rights reserved
The impacts of the covid-19 pandemic on liver transplant patients; Time to change the priorities
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