Optimization of flapping-wing micro aircrafts based on the kinematic parameters using genetic algorithm method

In this paper the optimization of kinematics, which has great influence in performance of flapping foil propulsion, is investigated. The purpose of optimization is to design a flapping-wing micro aircraft with appropriate kinematics and aerodynamics features, making the micro aircraft suitable for transportation over large distance with minimum energy consumption. On the point of optimal design, the pitch amplitude, wing reduced frequency and phase difference between plunging and pitching are considered as given parameters and consumed energy, generated thrust by wings and lost power are computed using the 2D quasi-steady aerodynamic model and multi-objective genetic algorithm. Based on the thrust optimization, the increase in pitch amplitude reduces the power consumption. In this case the lost power increases and the maximum thrust coefficient is computed of 2.43. Based on the power optimization, the results show that the increase in pitch amplitude leads to power consumption increase. Additionally, the minimum lost power obtained in this case is 23% at pitch amplitude of 25°, wing reduced frequency of 0.42 and phase angle difference between plunging and pitching of 77°. Furthermore, the wing reduced frequency can be estimated using regression with respect to pitch amplitude, because reduced frequency variations with pitch amplitude is approximately a linear function

Characteristics of dibenzothiophene desulfurization by Rhodococcus erythropolis R1 and its Dsz-negative mutant

Introduction: Biodesulfurization is used as a selective method for lowering the sulfur content of petroleum products. Materials and methods: A sulfur-oxidation bacterial strain named Rhodococcus erythropolis R1 (NCBI GenBank Accession No. GU570564) was used in this study for desulfurization of dibenzothiophene (DBT). Results: The induced culture of strain R1 was able to produce 2-hydroxybiphenyl (2- HBP) from DBT followed 4S pathway without further degrading carbon backbone. This process confirmed by gas chromatography (GC) analysis. The specific activity of DBT desulfurization by R1 was 45 µM (g dry wt)-1 h-1. The addition of Tween 80 as surfactant and glycerol as carbon source determines a 100% rate of DBT-desulfurization during 3 days. The heavy plasmid detected in R1 strain carries dsz genes responsible for biodesulfurization of DBT that was shown by PCR reaction. The mutant strains which had lost this plasmid also had lost desulfurization phenotype. Both mutant and wild strain were sensitive to high concentration of 2-HBP and some antibiotics. Discussion and conclusion: Strain R1 desulfurize DBT through the sulfur-specific degradation pathway or 4S pathway with the selective cleavage of carbon-sulfur (C-S) bonds without reducing the energy content. Addition of surfactant enhanced the desulfurization of DBT by increasing its bioavailability and also could improve the growth and desulfurization rate. The location of desulfurization genes was on a heavy plasmid in strain R1. Based on the results of this study, R. erythropolis R1 could serve as a model system for efficient biodesulfurization of petroleum oil without reducing the energy value

Learning Organizations is more successful Than Others

Knowledge and learning are among the important factors in organizations and are inevitable for their survival. Organizations are the result of the way of thinking and acting of their members. Therefore, if we want an organization to change, we should give enough time to individuals to change their way of thinking and acting. It is obvious that we cannot achieve such changes by intensifying training courses and/or the method of order and control management. Organizational learning requires introducing new management ideas, methods and tools. By providing opportunities for doing new works, members of the organization will achieve a stable capacity for change. Organizational learning has been paid increasing attention by the organizations which are interested in competitive advantage, innovation, and efficiency. Traditionally, learning has been defined as a process by which individuals will acquire new knowledge and insight as a result of changing their behaviors and actions. Learning organization is an organization which is managed consciously towards learning, and learning is an important component in its values, visions, objectives, evaluations, and daily operations. Learning is a process which includes quadripartite mechanisms which themselves include learning environment, recognition of developmental and learning needs, realization of developmental and learning needs, and utilizing learning in work environment. To focus on learning means to concentrate on making changes in an extensive level of individuals, groups, and organizations. Since environmental change is a constant and continuous action and an open and unpredictable process in nature, learning plays a critical and sensitive role in aligning organizational forces in this unreliable environment and moving towards a glorious, pervasive, and learning organization. Keywords: Learning, learning Organizations, Human Resource

Comparison of Three Different Techniques of Inverted Internal Limiting Membrane Flap in Treatment of Large Idiopathic Full-Thickness Macular Hole.

Purpose: To evaluate and compare three different techniques of inverted internal limiting membrane (ILM) flap in the treatment of large idiopathic full-thickness macular hole. Methods: In a comparative interventional case series, 72 eyes from 72 patients with large (\u3e 400 µm) full-thickness macular hole were randomly enrolled into three different groups: group A - hemicircular ILM peel with temporally hinged inverted flap; group B - circular ILM peel with temporally hinged inverted flap; and group C - circular ILM peel with superior inverted flap. Best-corrected visual acuity (BCVA), anatomical closure rate, and ellipsoid zone (EZ) or external limiting membrane (ELM) defects were evaluated preoperatively, at week 1, and months 1, 3 and 6 after surgery. Results: There were 24 eyes in group A, 23 in group B, and 25 in group C. In all three groups, larger diameter macular hole was associated with worse preoperative visual acuity (r=0.625, P\u3c0.001). Mean BCVA improved significantly in all three groups 6 months after surgery (0.91vs 0.55, p\u3c0.001). 6 months after surgery, mean BCVA improved from 0.91 logMAR to 0.52±0.06 in group A, 0.90 to 0.53±0.06 in group B, and 0.91 to 0.55±0.11 in group C. In group A vs. B vs. C, improvement of BCVA was 0.380±0.04 vs. 0.383±0.04 vs. 0.368±0.11 logMAR, with no statistically significant difference between groups (P=0.660). The rate of successful hole closure was 87.5% vs. 91.3% vs. 100%. Although the closure rate was 100% in Group C (circular ILM peel with superiorly hinged inverted flap), this difference was not statistically significant (P=0.115). Conclusion: ILM peel with an inverted flap is a highly effective procedure for the treatment of large, full-thickness macular hole. Different flap techniques have comparable results, indicating that the technique can be chosen based on surgeon preference

Effect of Plant Oils upon Lipase and Citric Acid Production in Yarrowia lipolytica Yeast

The nonconventional yeast Yarrowia lipolytica degrades very efficiently hydrophobic substrates to produce organic acids, single-cell oil, lipases, and so forth. The aim of this study was to investigate the biochemical behavior and simultaneous production of valuable metabolites such as lipase, citric acid (CA), and single-cell protein (SCP) by Yarrowia lipolytica DSM 3286 grown on various plant oils as sole carbon source. Among tested plant oils, olive oil proved to be the best medium for lipase and CA production. The Y. lipolytica DSM 3286 produced 34.6 ± 0.1 U/mL of lipase and also CA and SCP as by-product on olive oil medium supplemented with yeast extract. Urea, as organic nitrogen, was the best nitrogen source for CA production. The results of this study suggest that the two biotechnologically valuable products, lipase and CA, could be produced simultaneously by this strain using renewable low-cost substrates such as plant oils in one procedure

Effect of HA Nanoparticles on Adsorption of Vitamin D3 on Super-Hydrophobic PA6 Nanofibrous Scaffold

Vitamin D3 has significant roles in bone growth and the prevention of osteoporotic fractures. The present study investigated the effect of hydroxyapatite nanoparticles decoration onto polyamide-6 nanofibrous scaffold on adsorption behaviour of Vitamin D3. To synthesize the nanofibrous scaffold, an electrospinning device was used, and the surface of the scaffold was characterized by scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, and measurement of the water contact angle. The antibacterial activity test against E. coli and S. aureus bacteria indicated no such activity of pristine and hydroxyapatite decorated scaffold. The results demonstrated that a hydrophobic and high porous scaffold was formed, and hydroxyapatite nanoparticles were distributed inside the polyamide-6 nanofibers homogenously. Results showed that the hydroxyapatite nanoparticles improved the adsorption efficiency of polyamide-6 scaffold. It was found that the amount of adsorbed Vitamin D3 molecules onto the polyamide6/HA scaffold was rapid during the first hour of immersion (24.4 ng.cm-3), then declined over the next 3 h, and eventually reached a stable percentage of about 10.3 ng.cm-3. This phenomenon appears to be related to the high adsorption potential of porosities and the hydrophobic nanofibers during the first stage of immersion and non-occupied hydroxyapatite ceramic sites during the final stage of immersion. Keywords: Hydroxyapatite; Nanofibrous scaffold; Surface adsorption; Vitamin D3

Intravitreal Medications for Retinal Vein Occlusion: Systematic Review and Meta-analysis

Purpose: To evaluate the outcomes of different intravitreal injections for the treatment of retinal vein occlusion including central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). Methods: PubMed, Cochrane, the metaRegister of ControlledTrials, and ClinicalTrials were searched for intravitreal anti-Vascular Endothelial Growth Factor (VEGF) and steroids with relevant keywords and date limitation of 2009-2018. Meta-analysis was performed on studies that met the defined inclusion criteria. Main outcomes were visual acuity (VA) and central macular thickness (CMT). Results: Out of 681 studies, 36 articles (including 21 reporting CRVO and 15 dealing with BRVO) were selected for systematic review. All five intravitreal drugs including triamcinolone, dexamethasone, ranibizumab, bevacizumab, and aflibercept showed improvement of CMT and VA as compared to placebo or laser treatment. Six randomized controlled trials were selected for meta-analysis in RVO patients. The pooled mean difference of visual improvement between sham and ranibizumab was 12.7 Early Treatment for Diabetic Retinopathy Study (ETDRS) letters (95%CI: 11.00 to 13.2), and the pooled mean difference in CMT reduction was 221 μm (95%CI: 153 to 284); both changes were significantly in favor of ranibizumab. The pooled mean difference of visual improvement between bevacizumab and triamcinolone was 5.3 ETDRS letters in favor of bevacizumab (95%CI: 16 μm to 17.5 μm). Triamcinolone led to 68.1 μm greater CMT reduction than bevacizumab (95%CI: 58 μm to 76 μm). However, none of these differences were statistically significant. Conclusion: Treatment with anti-VEGF agents in RVO is superior to observation. No significant difference was seen between the eyes treated with bevacizumab or triamcinolone based on these results

Renal Function following Fluorescein Angiography in Diabetic Patients with Chronic Kidney Disease

Purpose: To evaluate the effect of fluorescein dye usage on renal function in patients with diabetic retinopathy (DR) and chronic kidney disease (CKD). Methods: Diabetic patients with retinopathy who were candidate for fundus fluorescein angiography (FA) were evaluated for serum creatinine and urea levels within five days prior to performing the FA. Serum creatinine levels of 1.5 mg/dl or more in males and 1.4 mg/dl or more in females were both identified as CKD and were included in the study. An increase of 0.5 mg/dl or 25% in creatinine after FA was considered as contrast-induced acute kidney injury (AKI). Estimated glomerular filtration rate (eGFR) was also calculated for all patients using a CKD-Epi formula. CKD grading was determined based on eGFR values. Results: Forty-two patients agreed to participate, of which 23 (54.8%) were male. Seventeen patients were identified with grade 3a or lower CKD, 12 with grade 3b, 11 with grade 4, and two with grade 5 CKD. Considering all grades of CKD, the mean blood urea before and after angiography was 58.48 ± 26.7 and 57 ± 27.81 mg/dl, respectively (P = 0.475). The mean serum creatinine before and after the test was 1.89 ± 1.04 and 1.87±0.99 mg/dl, respectively (P = 0.993). The mean eGFR before and after the test was 44.024 ± 23.5447 and 43.850 ± 21.8581 mL/min/1.73 m2 (P = 0.875). Conclusion: According to the findings of this study, FA does not seem to further deteriorate kidney function in patients with diabetic associated CKD

La gestión sostenible y flexible del recurso humano en las organizaciones innovadoras

In response to the changes in economies and technology in recent decades, research in organizational theories have been focused toward innovative and entrepreneurial organizations. A research issue in this evolving research endeavor is adaptation of human resource management and the establishment of a sustainable human resource management. This paper investigates the main characteristics of a sustainable HRM in innovative organizations. The aim is to identify sustainable HRM as a key toward competing in turbulent markets. The problem statement is to find the relationship between psychological capital, HR flexibility and sustainable HRM in innovative organizations. Three main variables of HR flexibility, HR sustainability and psychological capital form the theoretical model of this study; and four hypotheses are developed based on this model. Findings do not reject any of four hypotheses, so it is concluded that psychological capital and HR flexibility has positive and meaningful effect on sustainable HRM; and in addition, psychological capital has positive and meaningful effect on sustainable HRM. Moreover, flexibility has moderate role in relationship between psychological capital and sustainable HRMEn respuesta a los cambios en las economías y la tecnología en las décadas recientes, la investigación en las teorías organizacionales ha estado enfocada en las empresas innovadoras y emprendedoras. Un tema de exploración en estos esfuerzos por una investigación cambiante se trata de la adaptación de la gestión del recurso humano (GRH) y el establecimiento de una gestión sostenible del recurso humano (GRH sostenible). Este artículo investiga las principales características de la GRH en las organizaciones innovadoras. El objetivo es identificar la GRH sostenible como clave para competir en mercados turbulen- tos. El problema planteado radica en encontrar la relación entre el capital psicológico y la flexibilidad en los recursos humanos y la GRH sostenible en organizaciones innovadoras. Tres importantes variables de la flexibilidad de los recursos humanos, la sostenibilidad de los recursos humanos y el capital psicológico forman el modelo teórico de este estudio; y se desarrollan cuatro hipótesis basadas en este modelo. Los hallazgos no rechazan ninguna de las cuatro hipótesis, por lo cual se concluye que el capital psicológico y la flexibilidad en los recursos humanos tienen un efecto positivo y significativo en la GRH sostenible, y adicional- mente, el capital psicológico tiene un efecto positivo y significativo en la GRH sostenible. Además, la flexibilidad desempeña un rol moderado en la relación entre capital psicológico y la GRH sostenibl