Experimental validation of a subject-specific finite element model of lumbar spine segment using digital image correlation

Pathologies such as cancer metastasis and osteoporosis strongly affect the mechanical properties of the vertebral bone and increase the risk of fragility fractures. The prediction of the fracture risk with a patient-specific model, directly generated from the diagnostic images of the patient, could help the clinician in the choice of the correct therapy to follow. But before such models can be used to support any clinical decision, their credibility must be demonstrated through verification, validation, and uncertainty quantification. In this study we describe a procedure for the generation of such patient-specific finite element models and present a first validation of the kinematics of the spine segment. Quantitative computed tomography images of a cadaveric lumbar spine segment presenting vertebral metastatic lesions were used to generate the model. The applied boundary conditions replicated a specific experimental test where the spine segment was loaded in compression-flexion. Model predictions in terms of vertebral surface displacements were compared against the full-field experimental displacements measured with Digital Image Correlation. A good agreement was obtained from the local comparison between experimental data and simulation results (R2 > 0.9 and RMSE% <8%). In conclusion, this work demonstrates the possibility to apply the developed modelling pipeline to predict the displacement field of human spine segment under physiological loading conditions, which is a first fundamental step in the credibility assessment of these clinical decision-support technology

Dual-acting stapled peptides target both HIV-1 entry and assembly

Background: Previously, we reported the conversion of the 12-mer linear and cell-impermeable peptide CAI to a cell-penetrating peptide NYAD-1 by using an i,i + 4 hydrocarbon stapling technique and confirmed its binding to the C-terminal domain (CTD) of the HIV-1 capsid (CA) protein with an improved affinity (Kd ~ 1 μM) compared to CAI (Kd ~ 15 μM). NYAD-1 disrupts the formation of both immature- and mature-like virus particles in in vitro and cell-based assembly assays. In addition, it displays potent anti-HIV-1 activity in cell culture against a range of laboratory-adapted and primary HIV-1 isolates.&lt;p&gt;&lt;/p&gt; Results: In this report, we expanded the study to i,i + 7 hydrocarbon-stapled peptides to delineate their mechanism of action and antiviral activity. We identified three potent inhibitors, NYAD-36, -66 and -67, which showed strong binding to CA in NMR and isothermal titration calorimetry (ITC) studies and disrupted the formation of mature-like particles. They showed typical α-helical structures and penetrated cells; however, the cell penetration was not as efficient as observed with the i,i + 4 peptides. Unlike NYAD-1, the i,i + 7 peptides did not have any effect on virus release; however, they impaired Gag precursor processing. HIV-1 particles produced in the presence of these peptides displayed impaired infectivity. Consistent with an effect on virus entry, selection for viral resistance led to the emergence of two mutations in the gp120 subunit of the viral envelope (Env) glycoprotein, V120Q and A327P, located in the conserved region 1 (C1) and the base of the V3 loop, respectively.&lt;p&gt;&lt;/p&gt; Conclusion: The i,i + 7 stapled peptides derived from CAI unexpectedly target both CA and the V3 loop of gp120. This dual-targeted activity is dependent on their ability to penetrate cells as well as their net charge. This mechanistic revelation will be useful in further modifying these peptides as potent anti-HIV-1 agents.&lt;p&gt;&lt;/p&gt

Numerical Study of the Optical Response of ITO-In2O3 Core-Shell Nanocrystals for Multispectral Electromagnetic Shielding

Nowadays materials to protect equipment from unwanted multispectral electromagnetic waves are needed in a broad range of applications including electronics, medical, military and aerospace. However, the shielding materials currently in use are bulky and work effectively only in a limited frequency range. Therefore, nanostructured materials are under investigation by the relevant scientific community. In this framework, the design of multispectral shielding nanomaterials must be supplemented with proper numerical models that allow dealing with non-linearities and being effective in predicting their absorption spectra. In this study, the electromagnetic response of metal-oxide nanocrystals with multispectral electromagnetic shielding capability has been investigated. A numerical framework was developed to predict energy bands and electron density profiles of a core-shell nanocrystal and to evaluate its optical response at different wavelengths. To this aim, a finite element method software is used to solve a non-linear Poisson's equation. The numerical simulations allowed to model the optical response of ITO-In2O3 core-shell nanocrystals and can be effectively applied to different nanotopologies to support an enhanced design of nanomaterials with multispectral shielding capabilities

Design and Characterization of Modified Comb Patch Antennas

This work deals with the proposal of a novel type of microstrip antenna, called MCPA the modified comb patch antenna. The proposed antennas is composed of n parallel conductors, fed by a common microstrip. A dedicated mathematical framework, based on the multiconductors transmission line formalism, is proposed for antenna analysis and design. The analytical model is numerically validated with full-wave simulations, resulting in a 5% error in the predicted resonant patch length. A numerical study of antenna matching, size, radiation performance is carried out. The matching increases as the number of conductors increases, whilst gain of comb antennas made of n conductors are about half dB higher than the equivalent full patch counterpart. Then, an eighty conductors was realized and measured to assess the frequency response of the antenna, as well as its radiation performances. An error of 1% between the predicted and measured value resonance frequency was observed. A difference of about 0.67 dB was found for the measured maximum antenna gain, with respect to the simulated one. The proposed antenna design is appealing for printed electronics and wearable, on-textile applications

Microwaves as Diagnostic Tool for Pituitary Tumors: Preliminary Investigations

To date, tumors, the second cause of death worldwide, are a modern medicine plight. The development of rapid, cost-effective and reliable prevention and diagnostics tools is mandatory to support clinicians and ensure patients' adequate intervention. Pituitary tumors are a class of neoplasm, which calls for suitable and ad hoc diagnostic tools. Recently, microwaves have gained interest as a non-ionizing, non-invasive valuable diagnostic approach for identifying pathologic tissues according to their dielectric properties. This work deals with the preliminary investigation of the feasibility of using microwaves to diagnose pituitary tumors. In particular, it focuses on benign tumors of the adenohypophysis, e.g., the pituitary adenomas. It is assumed to access the region of interest of the pituitary region by following a trans-sphenoidal approach. The problem was modeled by developing an equivalent transmission line model of the multi-layered, lossy tissues (front bone of sphenoid sinuses, air in the sinuses, posterior bone of sphenoid sinuses, the pituitary gland and the tumor). The forward problem was developed to investigate the transmission coefficient for identifying the most favorable propagation conditions. Then, it was analyzed if, by the solution of an inverse problem, it is possible to reconstruct the permittivity and electrical conductivity profiles and identify the tumor presence. The results are promising since a maximum reconstruction error of 8% is found, in the worst case, thus paving the way for the use of microwaves for the diagnosis of pituitary tumors

A Periodic Transmission Line Model for Body Channel Communication

Body channel communication (BCC) is a technique for data transmission exploiting the human body as communication channel. Even though it was pioneered about 25 years ago, the identification of a good electrical model behind its functioning is still an open research question. The proposed distributed model can then serve as a supporting tool for the design, allowing to enhance the performances of any BCC system. A novel finite periodic transmission line model was developed to describe the human body as transmission medium. According to this model, for the first time, the parasitic capacitance between the transmitter and the receiver is assumed to depend on their distance. The parameters related to the body and electrodes are acquired experimentally by fitting the bio-impedentiometric measurements, in the range of frequencies from 1 kHz to 1 MHz, obtaining a mean absolute error lower than 4° and 30 $Omega$ for the phase angle and impedance modulus, respectively. The proposed mathematical framework has been successfully validated by describing a ground-referred and low-complexity system called Live Wire, suitable as supporting tool for visually impaired people, and finding good agreement between the measured and the calculated data, marking a ±3% error for communication distances ranging from 20 to 150 cm. In this work we introduced a new circuital approach, for capacitive-coupling systems, based on finite periodic transmission line, capable to describe and model BCC systems allowing to optimize the performances of similar systems

Generation of Free Carriers in MoSe2 Monolayers Via Energy Transfer from CsPbBr3 Nanocrystals

Transition metal dichalcogenide (TMDCs) monolayers make an excellent component in optoelectronic devices such as photodetectors and phototransistors. Selenide-based TMDCs, specifically molybdenum diselenide (MoSe2) monolayers with low defect densities, show much faster photoresponses compared to their sulfide counterpart. However, the typically low absorption of the atomically thin MoSe2 monolayer and high exciton binding energy limit the photogeneration of charge carriers. Yet, integration of light-harvesting materials with TMDCs can produce increased photocurrents via energy transfer. In this article, it is demonstrated that the interaction of cesium lead bromide (CsPbBr3) nanocrystals with MoSe2 monolayers results into an energy transfer efficiency of over 86%, as ascertained from the quenching and decay dynamics of the CsPbBr3 nanocrystals emission. Notably, the increase in the MoSe2 monolayer emission in the heterostructure accounts only for 33% of the transferred energy. It is found that part of the excess energy generates directly free carriers in the MoSe2 monolayer, as a result of the transfer of energy into the exciton continuum. The efficiency of the heterostructure via enhanced photocurrents with respect to the single material unit is proven. These results demonstrate a viable route to overcome the high exciton binding energy typical for TMDCs, as such having an impact on optoelectronic processes that rely on efficient exciton dissociation

Phosphodiesterase type-5 inhibitor tadalafil modulates steroid hormones signaling in a prostate cancer cell line

Background: The androgen receptor (AR) plays a key role in normal prostate homeostasis and in prostate cancer (PCa) development, while the role of aromatase (Cyp19a1) is still unclear. We evaluated the effects of a treatment with Tadalafil (TAD) on both these proteins. Methods: Androgen-sensitive human PCa cell line (LnCAP) was incubated with/without TAD (10−6 M) and bicalutamide (BCT) (10−4 M) to evaluate a potential modulation on cell proliferation, protein and mRNA expression of Cyp19a, AR and estrogen receptor-β (ERβ), respectively. Results: TAD increased early AR nuclear translocation (p &lt; 0.05, after 15 min of exposure), and increased AR transcriptional activity (p &lt; 0.05) and protein expression (p &lt; 0.05) after 24 h. Moreover, after 24 h this treatment upregulated Cyp19a1 and ERβ mRNA (p &lt; 0.05 and p &lt; 0.005 respectively) and led to an increase in protein expression of both after 48 h (p &lt; 0.05). Interestingly, TAD counteracted Cyp19a1 stimulation induced by BCT (p &lt; 0.05) but did not alter the effect induced by BCT on the AR protein expression. Conclusion: We demonstrate for the first time that TAD can significantly modulate AR expression and activity, Cyp19a1 and ERβ expression in PCa cells, suggesting a specific effect of these proteins. In addition, TAD potentiates the antiproliferative activity of BCT, opening a new clinical scenario in the treatment of PCa

A Simple Blass Matrix Design Strategy for Multibeam Arbitrary Linear Antenna Arrays

Multibeam antenna arrays are currently recognized as one of the enabling technologies for the next-generation communication standards. One of the key components of these systems is the beamforming network (BFN) that implements the array element excitations. This article addresses this issue by presenting a novel strategy to realize an analog feeding network, which allows an arbitrary linear array (LA) to radiate multiple arbitrary beams. In particular, an iterative procedure is conceived to design a Blass matrix using an identical directional coupler for all nodes, resulting in a very simple structure suitable for large-scale production. Two applications with arbitrary directions are illustrated as proofs-of-concept for the developed architecture: a dual-beam configuration with a null involving an aperiodic LA, and a four-beam configuration involving a periodic LA. For this second application, the effectiveness of the proposed solution is further verified by full-wave simulations and experimental measurements carried out on a fabricated prototype