131 research outputs found

    Geometric algebra techniques in flux compactifications

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    We study `constrained generalized Killing (s)pinors', which characterize supersymmetric flux compactifications of supergravity theories. Using geometric algebra techniques, we give conceptually clear and computationally effective methods for translating supersymmetry conditions into differential and algebraic constraints on collections of differential forms. In particular, we give a synthetic description of Fierz identities, which are an important ingredient of such problems. As an application, we show how our approach can be used to efficiently recover results pertaining to N=1 compactifications of M-theory on eight-manifolds.Comment: 70 page

    Human Resources Professional Development within the Knowledge-Based Economy Organizations

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    Through the present paper, we identified and argumented one of the most important consequences of the present business environment: appearance and, gradually, growth of differences between two categories of representants: human resources with high formation, strongly connected to the environment, who impose and even anticipate change, being fascinated by the development perspectives, unlike people always surprised by what is happening, sometimes lost by the predicable absence, having a continuous “fight” for keeping the other’s rhythm. The solution is represented by motivation and formation programs, on medium and long term in order to offer sustainable results. Consequently, from the organization management point of view, the most appropriate instrument for accomplishing and implementing this is the strategy, as an exponent of organization mission and objectives, in correlation with human resources, technical and material resources, financial and informational resources restrictions, and, moreover, the actions ways for accomplishing the competitive advantage.Small and medium enterprises (SMEs), human resources, professional development, motivation, economic performances, knowledge-based economy.

    Influence of nucleation centers upon solvothermal growth of silver nano/microcrystals

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    Silver nano/microcrystals were obtained at medium pressure in a microwave field by using the solvothermal synthesis. In order to evaluate the nucleation centers’ influence upon the formed crystals’ morphology, investigations were conducted using scaffolds to stimulate their heterogeneous nucleation. Therefore, besides the silver and chloride nanocrystals used as nucleation centers, SiOx type spheres were used. The results indicate that the presence of the heterogeneous nucleation centers on the SiOx scaffolds plays a crucial role in the silver nano/microcrystals morphology

    Carbon Dioxide Capture in the Iron and Steel Industry: Thermodynamic Analysis, Process Simulation, and Life Cycle Assessment

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    The iron and steel sector is one of the dominant drivers behind economic and social progress, but it is also very energy-intensive and hard-to-abate, making it a major cause of global warming. Improving energy efficiency, introducing hydrogen for direct reduction, and utilising CCS technologies are the three most viable options for reducing CO2 emissions from steel mills. This investigation deals with a life cycle comparison of three different carbon capture processes, the inventory data of which have been obtained using process simulation based on rigorous phase and chemical equilibrium equations. In-silico models for the absorption of carbon dioxide employing MDEA, membranes, or sodium hydroxide to produce sodium bicarbonate have been developed and compared from a life cycle viewpoint. The research findings showed a variable amount of CO2 removal in the three cases, where membranes achieved the best performance (95 % CO2 removal). Since NaOH absorption produces a valuable by-product (sodium bicarbonate, which is commonly produced by Solvay process), the other two technologies were modified to integrate the utilisation of CO2 for the synthesis of sodium bicarbonate with NaOH rather than transporting and storing the carbon dioxide. As a result, this production pathway for sodium bicarbonate generates lower environmental burdens than traditional Solvay process. The environmental performances of the alternatives are nearly equal, even though the environmental impacts associated with capturing the CO2 and subsequently reacting with NaOH are always slightly higher than those involved with reacting directly during absorption. Among the evaluated alternatives, the direct conversion to sodium bicarbonate appears to be the most promising approach for converting CO2 emissions in the steel sector

    Pharmacoepidemiologic investigation in acute renal cholic in children

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    Acute renal colic is one of the most intense pains in pathology and represents a urologic and nephrologic emergency. This exploratory study was performed on 86 patients with a ages between 10 and more than 18 which completed a questionnaire consisting of some questions about intensity of acute renal colic measured with the visual analogue scale (range=0-10), associated symptoms and the drugs used to reduce pain. In summary this study shows that in most of the patients the pain semnificativelly affects the normal daily activities. Drug therapy plays an important role in pain management. Renal colic pain management consists especially in using spasmolytic drugs and their association with analgesics or anti-inflammatory drugs

    Revealing a Pre-neoplastic Renal Tubular Lesion by p-S6 Protein Immunohistochemistry after Rat Exposure to Aristolochic Acid

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    Aristolochic acid (AA) has, in the last decade, become widely promoted as the cause of the Balkan endemic nephropathy and associated renal or urothelial tumours, although without substantial focal evidence of the quantitative dietary exposure via bread in specific households in hyperendemic villages. Occasional ethnobotanical use of Aristolochia clematitis might be a source of AA, and Pliocene lignite contamination of well-water is also a putative health risk factor. The aim of this study was two-fold: to verify if extracts of A. clematitis and Pliocene, or AA by itself, could induce the development of renal or urothelial tumours, and to test the utility of the ribosomal protein p-S6 to identify preneoplastic transformation. Rats were given extracts of A. clematitis in drinking water or AA I, by gavage.  After seven months, renal morphology was studied using conventional haematoxylin and eosin and immunohistochemistry for ribosomal p-S6 protein.  Plant extracts (cumulative AA approximately 1.8 g/kg b.w.) were tolerated and caused no gross pathology or renal histopathological change, with only faint diffuse p-S6 protein (except in the papilla) as in controls. Cumulative AA I (150 mg/kg b.w. given over 3 days) was also tolerated for seven months by all recipients, without gross pathology or kidney tumours. However, p-S6 protein over-expression was consistent particularly within the renal papilla. In one case given AA I, intense p-S6 protein staining of a proximal tubule fragment crucially matched the pre-neoplastic histology in an adjacent kidney section.  We briefly discuss these findings, which compound uncertainty concerning the cause of the renal or upper urinary tract tumours of the Balkan endemic nephropathy

    Adjunctive use of a nanocolloidal silver-based local antiseptic solution in the nonsurgical treatment of periodontitis: A split-mouth clinical study

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    Objectives. The aim of the present study was to evaluate the potential additional clinical benefit of a commercial nanocolloidal silver-based local antiseptic used as irrigation solution after subgingival mechanical instrumentation. Material and methods. Periodontitis patients were treated following the current guidelines. Two randomly assigned hemiarches of each patient received subgingival mechanical instrumentation plus irrigations with the commercial product (experimental group); the other two hemiarches received mechanical instrumentation plus saline irrigations (control group). A clinical periodontal examination at baseline moment and after 3 months was performed. The parameters considered for analysis were oral hygiene index (IHI), bleeding on probing score (BoP), periodontal pocket probing depth (PD), gingival recession (GR) and clinical attachment level (CAL). 72 sites were included in the analysis, the site with the highest PD/quadrant for each patient. Data were analyzed using GraphPad Prism version 8.0.1 (GraphPad Software Inc., La Jolla, CA, USA). p<0.05 was set as statistical significance level. Outcomes. Eighteen periodontitis patients were treated. All clinical parameters improved at re-evaluation, compared to baseline, both in experimental and control group. The differences were statistically significant in terms of IHI, BoP and PD reduction. At re-evaluation, there were no statistically significant differences between periodontal parameters registered in the experimental and control sites. Conclusions. The present study failed to prove an adjunctive clinical benefit of the antiseptic product in the nonsurgical treatment of periodontitis. These results support the gold standard role of subgingival mechanical instrumentation in the periodontitis’ therapeutic protocol

    Magnetically‐actuated microcages for cells entrapment, fabricated by laser direct writing via two photon polymerization

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    The manipulation of biological materials at cellular level constitutes a sine qua non and provocative research area regarding the development of micro/nano‐medicine. In this study, we report on 3D superparamagnetic microcage‐like structures that, in conjunction with an externally applied static magnetic field, were highly efficient in entrapping cells. The microcage‐like structures were fabricated using Laser Direct Writing via Two‐Photon Polymerization (LDW via TPP) of IP‐L780 biocompatible photopolymer/iron oxide superparamagnetic nanoparticles (MNPs) composite. The unique properties of LDW via TPP technique enabled the reproduction of the complex architecture of the 3D structures, with a very high accuracy i.e., about 90 nm lateral resolution. 3D hyperspectral microscopy was employed to investigate the structural and compositional characteristics of the microcage‐like structures. Scanning Electron Microscopy coupled with Energy Dispersive X‐Ray Spectroscopy was used to prove the unique features regarding the morphology and the functionality of the 3D structures seeded with MG‐63 osteoblast‐like cells. Comparative studies were made on microcage‐like structures made of IP‐L780 photopolymer alone (i.e., without superparamagnetic properties). We found that the cell‐seeded structures made by IP‐L780/MNPs composite actuated by static magnetic fields of 1.3 T were 13.66 ± 5.11 folds (p &lt; 0.01) more efficient in terms of cells entrapment than the structures made by IP‐L780 photopolymer alone (i.e., that could not be actuated magnetically). The unique 3D architecture of the microcage‐like superparamagnetic structures and their actuation by external static magnetic fields acted in synergy for entrapping osteoblast‐like cells, showing a significant potential for bone tissue engineering applications
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