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Samples of leaf, twig and fruit from ‘Mexican’ lime (Citrus aurantifolia) and grapefruit (Citrus paradisi) with symptoms of bacterial canker were collected from different provinces throughout Iran during spring and summers of 2010 and 2011. Yellow, gram-negative colonies were isolated from infected tissue samples. Results of pathogenicity assays indicated that some isolates incited tissue hyperplasia, hypertrophy and raised callus-like lesions typical of canker in hosts while other isolates stimulated flat necrotic and water-soaked lesions on leaves. Candidate samples of each group were identified according to morphological and physiological characteristics. Detections were also made using specific primers and partial sequencing of 16SrDNA for Pantoea group and gyrB for Xanthomonas group. Results showed that one group was characterized as the typical Xanthomonas citri subsp. citri strain while the other group containing most of the isolates was identified as Pantoea agglomerans. Samplings done frequently in different seasons revealed the presence of high populations of P. agglomerans with bacterial canker, especially in warmer and drier regions. These bacteria were able to incite canker-like symptoms on grapefruit seedlings and could be reisolated after two months.

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Because of increasing demands for using of rotating systems in high accuracy and high speed applications, in addition of specific condition of rotating systems, it is necessary to analyze these rotating systems characteristics. Tolerance analysis is a useful tool for estimating effects of dimensional and geometrical errors of effective parameters on functional characteristics in a mechanical system. Unlike other mechanical systems, in addition to the dimensional and geometrical errors, the accuracy of the rotary systems performance directly depend on the flexibility of parts and Non Repetitive Run-Out (NRRO) errors. In this paper, a new method is proposed for static and dynamic tolerance analysis of the rotary systems with the dimensional and geometrical errors, the flexibility effects, and the NRRO errors based on the tolerance zone model. First, using the small degrees of freedom concept, the dimensional and geometrical errors and the NRRO error are modeled in the tolerance zone. Then, based on a new strategy, the performance -assembly functions of the system for modeling the error propagation of the rotary system in the static and dynamic conditions are extracted. Then, using the proposed equations, sensitivities of the requirements such as the end of shaft position and the main natural frequency to tolerances are computed. To illustrate applicability of the proposed method, a rotary system is considered as a case study. Monte Carlo simulations are used for validation of the computational results from proposed method.

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The orientation of part in the additive manufacturing process is one of the most important factors should be considered in the additive manufacturing process. In the additive manufacturing process, the part orientation factor can significantly affect the part properties such as the surface roughness, strength, the manufacturing time and amount of support materials. The manufacturing time is a key factor that can influence the total production cost. Therefore, to minimize the manufacturing time, the optimum orientation of parts should be determined. In this paper, a new method is introduced to estimate the built time of the parts through the additive manufacturing process. According to the proposed method, a practical equation is extracted to estimate the built time of the parts with related to the number of layers and amount of the support materials. The method is capable to estimate the built time of a part associated to the part orientations. The efficiency of the proposed method is demonstrated through a case study in two different type of orientation, and the computational results are compared with the obtained results from the simulations in MankatiUM V5.3 and Repetier-Host software. The average of proposed method relative error in the first type of orientation in comparison with MankatiUM and Repetier-Host software results are, respectively, 5 and 10 percent and for the second type of orientation are 7 and 8 percent. Moreover, calculation cost of proposed method is 140 and 100 times faster than MankatiUM and Repetier-Host software, respectively.

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Additive Manufacturing (AM) or 3D printing is a method to build parts by adding layer-upon-layer of material. The selective laser sintering (SLS) method is one of the most important methods of additive manufacturing processes. The low time and the variety of materials used to build the parts are major advantages of SLS method. The high quality of the product is one of the main goals in the additive manufacturing processes. The part warping is one of the factors that reduce the quality of the products which are built by the SLS process. The hatching patterns and scan algorithms in the SLS process are important factors that affect the product quality. In this paper, the effective parameters of the SLS processes such as the scan vector length and the number of offsets or contours, the laser power, the laser speed, and the hitching spacing are optimally determined to minimize the part warping of the product based on the finite element simulations and Taguchi method. For this reason, SLS process has been modeled on the SLS process. Then, to illustrate and validate the accuracy and efficiency of the proposed method, and the computational results are compared to the obtained results from the experimental tests Using SLS containing CO2 laser. Finally, using the Taguchi design of Experiments, the process parameters have been changed at different levels and optimal parameters have been obtained.

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Fire blight, caused by Erwinia amylovora bacteria, is one of the well-known plant diseases in the world including major diseases of the fruit trees, especially apples and pears. In recent years, due to chemical nature of the pesticides damaging human health and environment, the importance of biological control is considered as alternative measure to manage plant diseases. To investigate the possibility of biological control of the pathogens, healthy foliar samples of apple, pear, and quince trees were collected from different regions of Kerman Province, Iran, and then, biocontrol activity of antagonist agents was evaluated under laboratory conditions. On the basis of the results, some of the antagonists could decrease the symptoms of the disease by 14.28-79.59%. Laboratory evaluation included investigating the disease severity in immature pears, biocontrol activity of antagonist agents in the plate assay, inhibitory siderophore production, biofilm formation capacity, drought stress tolerance, and silver nanoparticle synthesis capability, which showed that these antagonist agents could potentially control the disease. Among the 9 well-performed antagonistic isolates from apples and pears, Vr87 isolate was selected. The studies were confirmed by amplifying part of 16S rDNA region of the isolate, using specific primers. By comparing the results on the NCBI website, the selected isolate was identified as Enterobacter sp. genus. Among all selected isolates as successful factors in controlling fire blight pathogen, including isolated isolates and isolates in the collection of Vali-e-Asr University, Bacillus subtilis strain BsVRU1 in the Vali-e-Asr University collection, with 73.5% inhibition, had higher inhibitory power than the other antagonist isolates against the pathogen of fire blight disease.

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Biofilm formation and rhizosphere colonization of the plants are the main infrastructures for the biological control of the plant diseases. Bacteria accumulation in the protective layer, which results from their self-production of Exopolysaccharides (EPS), is called the biofilm. The formation of these complex structures originates from the multicellular behaviors of bacteria. Various elements can play a role in these mechanisms. In this study, we examined biofilm formation, root colonization, and salt tolerance to four concentrations of NaCl in the strains of Bacillus velezensis (Q12, US1, and UR1). The results showed that the biofilm strength plays an important role in the efficiency of tomato root colonization. Furthermore, UR1 that had defects in producing the surfactin, iturin, and fengycin using Ultrahigh-Performance Liquid Chromatography-High Resolution Electrospray Ionization Mass Spectrometry (UHPLC-HRESIMS), was incapable of tolerance to salinity, biofilm formation, competition, and rhizosphere colonization. Confocal Laser Scanning Microscopy (CLSM) studies showed that strains US1 and Q12 differed in the biofilm strength, the position of the bacteria that are located laterally, polar, or both, and root colonization. Q12 was introduced as the best strain in all these experiments. Also, based on the findings of this and previous studies, the possibility to create the subpopulations influenced by genetic diversity in Bacillus velezensis strains during biofilm formation is suggested.