Pores occlusion in MCM-41 spheres immersed in SBF and the effect on ibuprofen delivery kinetics: A quantitative model

MCM-41 silica particles have been synthesized with size in the low submicron range, loaded with ibuprofen and characterized by means of XRD, N₂ adsorption and scanning electron microscopy, coupled with EDS analysis both before and after contact with different volumes of simulated body fluid (SBF) at 37 °C up to 10 h.The particles do not show any change in morphology, composition and mesostructure as a consequence of soaking. MCM-41 spheres, though, are not inert towards SBF. Two processes take place, showing features independent from the soaking volume: (i) one within 1–2 h, bringing about dissolution of silica into the liquid phase up to a concentration of 2.2 mM and no change in the mesopore volume; (ii) the second, after an induction period of 1–2 h, bringing about a limited increase in the concentration of dissolved silica, but affecting severely the mesoporous volume, which decreases exponentially with time.Delivery curves differ significantly when varying the volume of SBF used. To account for release kinetics under the circumstances observed, a mathematical model is proposed, based on the standard Noyes–Whitney equation, taking into account both the SBF volume used and the mesopores occlusion, this latter through a time-dependent diffusion coefficient. A satisfactory agreement is observed, without the intervention of any adjustable parameter.     

Fine‐Tuning of Catalytic Properties of Catechol 1,2‐Dioxygenase by Active Site Tailoring

Choosing chloro : By reshaping the catalytic pocket of a catechol 1,2‐dioxygenase through a structural route alternative to evolution, novel engineered chlorocatechol dioxygenase‐like enzymes were obtained. Variants show an inversion of specificity with a preference for 4‐chlorocatechol and activity on the rarely recognised substrate 4,5‐dichlorocatechol.

     

Quantification of greenhouse gas emissions from sludge treatment wetlands

Constructed wetlands are nowadays successfully employed as an alternative technology for wastewater and sewage sludge treatment. In these systems organic matter and nutrients are transformed and removed by a variety of microbial reaction and gaseous compounds such as methane (CH₄) and nitrous oxide (N₂O) may be released to the atmosphere. The aim of this work is to introduce a method to determine greenhouse gas emissions from sludge treatment wetlands (STW) and use the method in a full-scale system. Sampling and analysing techniques used to determine greenhouse gas emissions from croplands and natural wetlands were successfully adapted to the quantification of CH₄ and N₂O emissions from an STW. Gas emissions were measured using the static chamber technique in 9 points of the STW during 13 days. The spatial variation in the emission along the wetland did not follow some specific pattern found for the temporal variation in the fluxes. Emissions ranged from 10 to 5400 mgCH₄/m² d and from 20 to 950 mgN₂O/m² d, depending on the feeding events. The comparison between the CH₄ and N₂O emissions of different sludge management options shows that STW have the lowest atmospheric impact in terms of CO₂ equivalent emissions (Global warming potential with time horizon of 100 years): 17 kgCO₂eq/PE y for STW, 36 kgCO₂eq/PE y for centrifuge and 162 kgCO₂eq/PE y for untreated sludge transport, PE means Population Equivalent.     

Can Serum Nitrosoproteome Predict Longevity of Aged Women?

Aging is characterized by increase in reactive oxygen (ROS) and nitrogen (RNS) species, key factors of cardiac failure and disuse-induced muscle atrophy. This study focused on serum nitroproteome as a trait of longevity by adopting two complementary gel-based techniques: two-dimensional differential in gel electrophoresis (2-D DIGE) and Nitro-DIGE coupled with mass spectrometry of albumin-depleted serum of aged (A, n = 15) and centenarian (C, n = 15) versus young females (Y, n = 15). Results indicate spots differently expressed in A and C compared to Y and spots changed in A vs. C. Nitro-DIGE revealed nitrosated protein spots in A and C compared to Y and spots changed in A vs. C only (p-value < 0.01). Nitro-proteoforms of alpha-1-antitripsin (SERPINA1), alpha-1-antichimotripsin (SERPINA3), ceruloplasmin (CP), 13 proteoforms of haptoglobin (HP), and inactive glycosyltransferase 25 family member 3 (CERCAM) increased in A vs. Y and C. Conversely, nitrosation levels decreased in C vs. Y and A, for immunoglobulin light chain 1 (IGLC1), serotransferrin (TF), transthyretin (TTR), and vitamin D-binding protein (VDBP). Immunoblottings of alcohol dehydrogenase 5/S-nitrosoglutathione reductase (ADH5/GSNOR) and thioredoxin reductase 1 (TRXR1) indicated lower levels of ADH5 in A vs. Y and C, whereas TRXR1 decreased in A and C in comparison to Y. In conclusion, the study identified putative markers in C of healthy aging and high levels of ADH5/GSNOR that can sustain the denitrosylase activity, promoting longevity.     

An energy-based control for an n-H-bridges multilevel active rectifier

This paper deals with the control of a multilevel n-H-bridges front-end rectifier. This topology allows n distinct dc buses to be fed by the same ac source offering a high loading flexibility suitable for traction applications as well as for industrial automation plants. However, this flexibility can lead the system to instability if the dc buses operate at different voltage levels and with unbalanced loads. Thus, linear controllers, designed on the basis of the small-signal linearization, are not effective any longer and stability can not be ensured as large-signal disturbances occur. The use of a passivity-based control (PBC) designed via energy considerations and without small-signal linearization properly fits stability problems related to this type of converter. The system has been split into n subsystems via energy considerations in order to achieve the separate control of each dc bus and its stability in case of load changes or disturbances generated by other buses. Then, a set of n passivity-based controllers (one for each subsystem) is adopted: the controllers are linked using dynamical parameters computed through energy balance equations. Hence, the system dc buses are independent and stable as experimental results demonstrate.     

Surface tension and viscosity of industrial alloys from parabolic flight experiments — Results of theThermoLab project

The surface tension and the viscosity of a series of industrial alloys have been measured by the oscillating drop technique with an electromagnetic levitation device under reduced gravity conditions in several parabolic flights. It was demonstrated that the 20 seconds of reduced gravity available in a parabola were sufficient for melting, heating into the liquid phase, and cooling to solidification of typically 7 mm diameter metallic specimen. The surface tension and the viscosity were obtained from the frequency and the damping time constant of the oscillation which were evaluated from the temperature signal of a highresolution pyrometer. Alloys processed included steels, Ni-based superalloys, and Ti-alloys which were supplied by industrial partners to the project. Three to four parabolas were sufficient to obtain the surface tension and the viscosity over a large range in temperature.     

On the numerical modelling of the multiphysics self piercing riveting process based on the finite element technique

The development of reliable numerical models permits to investigate the manufacturing processes with very low incremental costs or prototyping efforts hence it provides a relevant help in process optimisation and gives great opportunity for making maximum use of sparse process data [Shercliff HR, Lovatt AM. Selection of manufacturing process in design and the role of process modelling. Prog Mater Sci 2001;46:429–59].

Among others the metal forming processes have heavily benefited from the finite element numerical computing technology [Chenot JL, Massoni E. Finite element modelling and control of new metal forming processes. Int J Machine Tool Manuf 2006;46:1194–200].

The self piercing riveting (SPR) is a cold forming process which creates a strong mechanical interlock between two or more sheets by means of a semi-tubular rivet, which, pressed by a punch, pierces the upper sheet and flares into the bottom one. It is governed by complex multiphysics phenomena whose governing equations can be resolved using the finite element method.

In this paper all the governing equations are fully reported along with the mathematics of the resolving method needed for setting up and simulate a finite element model of the self piercing riveting of an aluminium alloy. A case study of the SPR of two sheets of the 6060T4 aluminium alloy using a steel rivet was investigated. The calculations were performed using the LsDyna finite element commercial code. The problems encountered and the solutions applied for the preparation of the model and the run of the calculation were presented and discussed. The obtained results were validated by comparison with data coming from a laboratory experiment.