Water in acid boralites: Hydration effects on framework B sites

Properties and behavior of protonated boron-containing zeolites at different hydration degree have been investigated by means of periodic DFT approaches. Geometry optimization and room-temperature Car-Parrinello molecular dynamics results, in line with experimental findings, indicate that the BO3-bound silanolic acid site typical of dry boralites should convert to a solvated H3O+ hydrogen bonded to tetrahedral BO4 at moderate water content. By increasing the water loading, the tetrahedral structure of the B site is stabilized and the physicochemical properties of the water molecules solvating the acid proton gradually approach the liquid-phase ones. A relevant role of structural and vibrational properties of the zeolite framework in the water-induced trigonal-to-tetrahedral transition at the B site is highlighted by simulation results

Monte Carlo studies for medical imaging detector optimization

This work reports on the Monte Carlo optimization studies of detection systems for Molecular Breast Imaging with radionuclides and Bremsstrahlung Imaging in nuclear medicine. Molecular Breast Imaging requires competing performances of the detectors: high efficiency and high spatial resolutions; in this direction, it has been proposed an innovative device which combines images from two different, and somehow complementary, detectors at the opposite sides of the breast. The dual detector design allows for spot compression and improves significantly the performance of the overall system if all components are well tuned, layout and processing carefully optimized; in this direction the Monte Carlo simulation represents a valuable tools. In recent years, Bremsstrahlung Imaging potentiality in internal radiotherapy (with beta-radiopharmaceuticals) has been clearly emerged; Bremsstrahlung Imaging is currently performed with existing detector generally used for single photon radioisotopes. We are evaluating the possibility to adapt an existing compact gamma camera and optimize by Monte Carlo its performance for Bremsstrahlung imaging with photons emitted by the beta- from 90 Y

Mechatronic face mask anti covid-19 to remotely record cardiorespiratory variables in farm’s workers engaged in jobs at high risk of infection

The most frequent prodromes of COVID-19 infection are fever, signs of respiratory diseases, cough and shortness of breath. Nevertheless, it is not infrequent that patients with COVID-19 also show cardiac symptoms. So, it is of importance to detect the prodromal symptoms of the COVID-19 infection in order to be able to make a diagnosis as quickly as possible to provide the immediate insertion of the infected people in isolation/therapy protocols. Here is presented a prototype of a smart face mask, named AG47-SmartMask that, in addition to the function of both an active and passive anti COVID-19 filter by an electro-heated filter brought to a minimum temperature of 38°C, it also allows the continuous monitoring of numerous cardio-pulmonary variables. Several specific sensors are incorporated into the mask to assess the inside mask temperature from which synchronous waving with the breathing was acquired the breath frequency, relative humidity, air pressure together and end tidal carbon dioxide percentage, and an auricular assessment of the body temperature, the heart rate and the percentage of oxygen saturation of haemoglobin. Sensors are embedded within an advanced ICT platform. To validate the AG47-SmartMask tool, were engaged twenty seven Farm’s workers of a vegetable packaging chain and they dressed the face mask device to simulate, while working, both tachypnea and cough, and the AG47-SmartMask faithfully quantified the simulated dyspnoic events

A 12-week vigorous exercise protocol in a healthy group of persons over 65: study of physical function by means of the senior fitness test

The aim of this study was to assess the effects of vigorous exercise on functional abilities bymeans of a Senior Fitness Test (SFT) in a group of elderly adults. Twenty healthy and inactive people performed vigorous exercise (VE: 12 men and 8 women, aged 69.6 ± 3.9 years). At the beginning of the study (T0) and after 3months (T1), each subject’s functional ability was tested formuscular strength, agility, cardiovascular fitness, flexibility, and balance.The VE was designed with continuous and interval exercise involving large muscle activities. Functional exercises were performed between 60% and 84% of heart rate reserve (HRR) for a duration of 65 minutes. Five out of the 6 SFTs performed were found significantly improved: Chair Stand (T0 12.4 ± 2.4, T1 13.5 ± 2.6, < 0.01), Arm Curl (T0 14.2 ± 3.6, T1 16.6 ± 3.6, < 0.01), 2 min step (T0 98.2 ± 15.7, T1 108.9 ± 16.2, < 0.01), Chair Sit-and-Reach (T0 −9.9 ± 7.7 cm, T1 1.7 ± 6.3 cm, < 0.01), and Back Scratch (T0 −15.8 ± 10.9 cm, T1 −8.4 ± 13.1 cm, < 0.01). Our results suggest that a high intensity protocol and functional exercises can improve functional mobility and muscle endurance in those over 65 years of age. SFTs are an effective method for assessing improvements in the functional capacity of elderly adults

Possible Assessment of Calf Venous Pump Efficiency by Computational Fluid Dynamics Approach

Three-dimensional simulations of peripheral, deep venous flow during muscular exercise in limbs of healthy subjects and in those with venous dysfunction were carried out by a computational fluid-dynamics (CFD) approach using the STAR CCM + platform. The aim was to assess the effects of valvular incompetence on the venous calf pump efficiency. The model idealizes the lower limb circulation by a single artery, a capillary bed represented by a porous region and a single vein. The focus is on a segment of the circuit which mimics a typical deep vein at the level of the calf muscle, such as the right posterior tibial vein. Valves are idealized as ball valves, and periodic muscle contractions are given by imposing time-dependent boundary conditions to the calf segment wall. Flow measurements were performed in two cross-sections downstream and upstream of the calf pump. Model results demonstrate a reduced venous return for incompetent valves during calf exercise. Two different degrees of valvular incompetence are considered, by restricting the motion of one or both valves. Model results showed that only the proximal valve is critical, with a 30% reduction of venous return during calf exercise in case of valvular incompetence: the net flow volume ejected by the calf in central direction was 0.14 mL per working cycle, against 0.2 mL for simulated healthy limbs. This finding appeared to be consistent with a 25% reduction of the calf ejection fraction, experimentally observed in chronic venous disease limbs compared with healthy limbs

Topology of amorphous tetrahedral semiconductors on intermediate lengthscales

Using the recently-proposed ``activation-relaxation technique'' for optimizing complex structures, we develop a structural model appropriate to a-GaAs which is almost free of odd-membered rings, i.e., wrong bonds, and possesses an almost perfect coordination of four. The model is found to be superior to structures obtained from much more computer-intensive tight-binding or quantum molecular-dynamics simulations. For the elemental system a-Si, where wrong bonds do not exist, the cost in elastic energy for removing odd-membered rings is such that the traditional continuous-random network is appropriate. Our study thus provides, for the first time, direct information on the nature of intermediate-range topology in amorphous tetrahedral semiconductors.Comment: 4 pages, Latex and 2 postscript figure

Chemically Induced Mismatch of Rings and Stations in [3]Rotaxanes

The mechanical interlocking of molecular components can lead to the appearance of novel and unconventional properties and processes, with potential relevance for applications in nanoscience, sensing, catalysis, and materials science. We describe a [3]rotaxane in which the number of recognition sites available on the axle component can be changed by acid-base inputs, encompassing cases in which this number is larger, equal to, or smaller than the number of interlocked macrocycles. These species exhibit very different properties and give rise to a unique network of acid-base reactions that leads to a fine pKa tuning of chemically equivalent acidic sites. The rotaxane where only one station is available for two rings exhibits a rich coconformational dynamics, unveiled by an integrated experimental and computational approach. In this compound, the two crown ethers compete for the sole recognition site, but can also come together to share it, driven by the need to minimize free energy without evident inter-ring interactions

The Quantum-Mechanical Position Operator in Extended Systems

The position operator (defined within the Schroedinger representation in the standard way) becomes meaningless when periodic boundary conditions are adopted for the wavefunction, as usual in condensed matter physics. We show how to define the position expectation value by means of a simple many-body operator acting on the wavefunction of the extended system. The relationships of the present findings to the Berry-phase theory of polarization are discussed.Comment: Four pages in RevTe