A Strategy for GC/MS Quantification of Polar Compounds via their Silylated Surrogates: Silylation and Quantification of Biological Amino Acids

Substitution of polar functionalized compounds with silylated (e.g., trimethylsilylated) surrogates prior to GC/ MS analysis is a widely used analytical strategy. Calibration is a most demanding step of this strategy. In fact, a calibration function is usually acquired by converting known amounts of the pure analyte to its silylated surrogate using the same conditions employed for processing unknown samples. The cumbersome need of acquiring a new calibration function prevents, to a large extend, the possibility of modifying silylation and instrumental settings on a sample by sample basis as would be appropriate in a number of cases. The modified standard additions calibration method, suggested in this paper, overcomes this difficulty by integrating in a single analytical procedure calibration and sample analysis. Furthermore, the suggested procedure compensates for matrix effects which may be a serious source of inaccuracy and is a tool that can be used during method development in order to find the most suitable silylation conditions for a given analyte. The implementation and benefits of the modified standard additions calibration method are explored in this paper on the basis of a symbolic but enlightening experiment dealing with the very representative GC/MS quantification of biological amino acids via their trimethylsilylated derivatives

Riboflavin (Vitamin B2) Assay by Adsorptive Cathodic Stripping Voltammetry (Adcsv) at the Hanging Mercury Drop Electrode (HMDE)

In this study the interactions of Riboflavin (Vitamin B2) with a mercury surface are investigated. Firstly, by using Cyclic Voltammetry, it is demonstrated that Riboflavin can be efficiently accumulated, by adsorption from buffered solutions containing an excess of NaClO4, onto the mercury drop of a HMDE. Secondly, it is shown that the adsorbed Riboflavin can be reduced through an electrochemical reaction whose stoichiometry is extricated by confronting simulated with experimental CV voltammograms acquired in a range of pH between about four and nine. Finally, the cathodic current, sustained by the surface reduction of Riboflavin, is exploited for assaying Riboflavin via Differential Pulse Adsorption Cathodic Stripping Voltammetry (DP AdCSV) within the frame of the standard additions calibration procedure. By applying the suggested DP AdCSV procedure with standard voltammetric equipment, typical DP settings and pre-electrolysis time of about 10 s, a linear response is maintained if Riboflavin concentration in the electrolysed solution does not exceed about 2 mg/l. On the other side, a limit of detection (expressed as the concentration of Riboflavin in the electrolysed solution) of 7 μg/l has been achieved with a pre-electrolysis time of 68 s

pH and Acid-Base Equilibrium Calculations via a Matrix Representation of Solutions of Acids and/or Bases

In this article we implement the idea of representing an aqueous solution of acids and/or bases with a matrix from which the pH and equilibrium concentrations of all species in any described solution can be extracted. Given that this matrix can be readily generated using an ad hoc MS Excel sheet, whatever pH calculation is reduced to the problem of selecting a row from the matrix by using as a guide the proton balance equation in the solution. A special scheme is presented allowing the needed proton balance relation to be derived from the specified solution data in all cases. This preserves the fundamental unity of the topic without sacrificing chemical understanding and simplicity. By consequence, the presented calculation technique is eminently suitable to be used in introductory courses as a complement, an extension or a substitute whenever the usual way of dealing with the topic (which, in general, consists in developing a menu of special cases, formulas and/or algebraic procedures) is judged insufficient. A MS Excel file named , attached to the present paper as supporting material, allows the matrix representation of any given solution to be developed in a very short time

Programming Visual Representations. Evolutions of Visual Identities between Tangible and Intangible

[EN] The communication design field it is considerably changed in the last 20 years and more as well as the role of the designer. Technology has modified the daily work tools, and new possible relations between the designer, the commitment, and the final user can be underlined. Observing some of the most experimental practices, new visual languages have drawn the attention, affected by innovative approaches and mixed competencies. The area of visual identities is especially of interest, not excluding other areas of experimentations. The phenomenon of the so-called dynamic or post-logo identities underlined the possibilities of using more fluid and expressive, variable, context related, processual, performative, non-linear, consistent visual languages instead of the usual and static repetition of a logo or an imposed series of rules (Felsing, 2010). However, also their contradictions in making recognizable an organization and in the visual identity daily management. An interesting evolution to be underlined is in the use of the digital tools, not anymore in a passive way but in an active way. Visual designers can build their digital tools basing them on design and esthetic needs. The designer is not anymore just the user of ready-made digital tools, becoming himself programmer of customized digital toolboxes by using open source codes or hardware like Arduino. Not just a DIY attitude but something that it is changing the control knobs of a design system in all its process and development. As far as technology support is relevant, technical matters are relegated in the background on behalf of abstraction and data parametrization that means on behalf of a meta-design level. The use of programming in creative and visual communication design processes “empowers the designer, freeing he from the constraints of predefined computational tools, and promoting creative freedom in the construction of visual metaphors” (Duro, Machado, Rebelo, 2012). The aim of this paper is to argue this recent evolution in the field of visual identities and the wider area of communication design practices.Guida, F.; Voltaggio, E. (2016). Programming Visual Representations. Evolutions of Visual Identities between Tangible and Intangible. En Systems&design:beyond processes and thinking. Editorial Universitat Politècnica de València. 419-430. https://doi.org/10.4995/IFDP.2015.3334OCS41943

Parachute emergency landing simulation and enhanced composite material characterization for General Aviation aircraft

General Aviation (GA) aircraft crashworthiness of the vehicle when it hits the ground after the parachute deployment is an important issue. The current dynamic emergency landing regulation (CS 23.562) defines the maximum human tolerant accelerations under both vertical and horizontal directions. This article aims to compare two different aircraft configurations: metal low-wing and composite high-wing ones. Both are two-seats and single-engine GA aircraft. The purpose of the analysis is to check whether the seats and restraint systems met human injury tolerance standards and to determine the possible impact on passengers in the cabin space due to shock loads. Finite element analysis of the fuselage sections for both configurations is performed using the commercial LS-Dyna solver. An extensive campaign of experimental tests has been performed on the composite samples for tuning and validating the model and to find the transition from an undamaged up to totally collapsed sample. The material of the composite fuselage has been characterized through experimental tests. The adopted material model has been refined to match with the performed experimental analysis, allowing high-fidelity modeling. A parametric analysis has been performed to determine the optimal impact angle in terms of lumbar injuries and loads transmitted by the seat belt due to aircraft contact with the ground, thereby increasing the level of safety. The investigations carried out may be an important indicator of the design of the parachute system

Failure Propagation Controlling for Frangible Composite Canister Design

The complexity in predicting the damage initiation and failure propagation controlling in composite structures is challenging. The focus of this paper is to design a potential component for new ship gunnels to make the composite canister affordable in structural applications by using a damage tolerant design approach. The design of a new tailgate configuration was investigated, taking into account the correct fragmentation of the structure to ensure a clear ejection while reducing the weight of the panels by exploiting the properties of the composite material. The complex geometry of the tailgate, the high impulse load, the energy transferred to the tailgate during missile impact, and how to safely break large panel flaps are elements that characterize the sizing of the composite component to meet the stringent ejection requirements in the life cycle of a missile during takeoff. The numerical simulations were performed using the LS/Dyna code and its explicit formulation was contemplated to take into account the geometrical, contact, and material non linearities

Made in Sud. L'industria tra intervento pubblico e territorio dilapidato

The policies supporting southern Italy, implemented since the Second World War o the end of the twentieth century, have contributed to reducing the gap whit the North of the country but these regions are still experiencing difficulties that are unresolved from a political and socio-economic point of view. This condition is reflected in the territorial forms, whose crisis today demands, from an urban planning point of view, pertinent reading and solution models of a strategic type and a regenerative approach. The framework that is traced with regard to public intervention in the South is centered on the role of three actors: big industry and the State, with their reciprocal intermingling, and the southern territorial milieu. From the territorial point of view, a critical relationship between the large industrial areas and the territories of medium and small towns around which the large production 'plates' were implanted, in particular, the Industrial Development Areas, was determined, among other outcomes. Through the case study of the province of Caserta, we suggest the need for an adequate analytical framework and a replicable regenerative approach where rural identities, abandonment, the historical palimpsest and a still persistent industrial vocation vie with each other, affecting the territory's future prospect