This paper proposes a novel method for integrating CMOS microelectronics with microwire-based electrodes for next generation implantable brain machine interfaces. There is strong evidence to suggest ...that microwire-based electrodes outperform micromachined and polymer-based electrodes in terms of signal integrity and chronic viability. Furthermore, it has been shown that the recording of Local Field Potentials (LFPs) is more robust to tissue damage and scar tissue growth when compared to action potentials. This work therefore investigates the suitability of microwire electrodes for LFP recording by studying the electrical properties of key materials. We identify Niobium (Nb) as a candidate material with highly desirable properties. There is however also an inherent incompatibility when it comes to connection of microwire-based electrodes to silicon chips. Here we present a new process flow utilising a recessed glass substrate for mechanical support, silicon interposer for interconnection, and electroplating for contact adhesion. Furthermore, the proposed structure lends itself to hermetic encapsulation towards gas cavity based micropackages.
This work presents a comprehensive study on single crystalline LaPt2Si2, in which superconductivity and a charge density wave (CDW) coexist. The usage of density functional theory (DFT) modeling and ...Inelastic Neutron Scattering has been the primary form of investigation, in order to determine all the characteristic features of the sample taken under consideration. From the results one can observe that the Fermi surface nesting is the primary contributor for the CDW wavevector ~qCDW = (1/3, 0, 0). In addition, the phonon density of states present two typical energy levels, with soft modes in the Pt3-Pt4 layer coherent with the presence of a CDW. The superconducting temperature has been estimated at Tc = 1.6 K. The experimental data from the inelastic instrument High Resolution Chopper Spectrometer (HRC) at the J-PARC neutron source are in good agreement with the theoretical simulations, showing the same energy levels for the polarization phonon modes (from 4 to 18 meV and from 32 to 42 meV).
Denna rapport presenterar en omfattande studie av enkristalls LaPt2Si2 i vilken supraledning och en laddningsdensitetsvåg (CDW) samexisterar. Användandet av DFT-modellering och neutronspridning har varit de huvudsakliga undersökningsmetoderna, för att bestämma alla karakteristiska drag hos det undersökta provet. Från resultaten kan observeras att den inneslutna Fermiytan är den huvudsakliga bidragaren till CDW-vågvektorn~qCDW = (1/3, 0, 0). Vidare visar den närvarande fonontillståndsdensiteten två typiska energinivåer, med mjuka lägen i Pt3-Pt4-skiktet, som stämmer överens med närvaron av en CDW. Den supraledande temperaturen har uppskattats till Tc = 1.6 K. Experimentella data från det inelastiska instrumentet HRC vid J-PARCs neutronkälla stämmer väl överens med teoretiska simuleringar, som visar samma energinivåer för polarisationsfononlägena (från 4 till 18 meV och från 32 till 42 meV).
Additive manufacturing is gaining popularity at a rapid rate and has been a resourceful production process to reduce material usage, wastage (scrap) and manufacturing costs for various applications. ...The project conducted, emphasizes on Thermoplastic Elastomer (TPE SE6300C-65A) material, which is a highly versatile compound, and has the ability to exhibit properties of both rubber (Elastomers) in terms of flexibility and plastic (Polymers) in terms of recyclability. Cost reduction without compromising quality is one of the important factors for industries. The project involves the use of TPE pellets to extrude filaments that could be used for 3D Printing. Filament extrusion involves process variables like Nozzle Temperature, De-humidification of pellets, Diameter of the nozzle, Distance of collection, Cooling and Angle of inclination of the extruder. These process variables are optimized to accomplish the desired quality of filament. The filament produced through extrusion is further used to make products using Fused Deposition Modeling (FDM). FDM also involves numerous process variables like Layer Thickness, Build Orientation, Print Infill, Print Speed etc. In this study, different test specimens, in terms of geometrical shapes are printed from the material, TPE SE6300C-65A and tested in order to understand how the surface features as well as the dimensional accuracy change with different process variables. It is observed that the surface topography produced throughout FDM process is majorly affected by the angle of orientation of the printed part. The main goal of this thesis is to give the reader a better understanding on which process variable, such as layer thickness, temperature and print speed affect the surface roughness of the models and also a comparison between these three variables, highlighting which is more or less affecting. It is also observed the dimensional accuracy of the real specimen deviate from the value input into the CAD software. The results obtained in this study clearly suggest that there is a lot of opportunities for future improvements especially regarding the dimensional accuracy, it is imperative to achieve the highest precision possible in order to have commercial values for the FDM 3D printing.
The mixed valence Cr compound NaCr\(_2\)O\(_4\), synthesized using a high-pressure technique, offers a unique playground for investigating unconventional physical properties in condensed matter. In ...the present study, muon spin rotation/relaxation (\(\mu^+\)SR) and high-resolution neutron powder diffraction (NPD) measurements were carried out to clarify the true magnetic ground state of this interesting compound. Our detailed study brings new insight, allowing us to confirm the existence of a commensurate antiferromagnetic order (C-AFM) and to extract its ordered Cr moment \(\mu^{\rm C}_{\rm Cr}=(4.30\pm0.01)\mu_B\). Such a value of the ordered moment is in fact compatible with the existence of high-spin Cr sites. Further, the value of the canting angle of the Cr spin axial vector is refined as \(\theta_{\rm c}=(8.8\pm0.5)^{\circ}\). Employing high-quality samples in combination with time-of-flight NPD, a novel magnetic supercell was also revealed. Such supercell display an incommensurate (IC)-AFM propagation vector (0~0~\({\textstyle \frac{1}{2}-}\delta\)), having an ordered moment \(\mu^{\rm IC}_{\rm Cr}=(2.20\pm0.03)\mu_B\). It is suggested that the C-AFM and IC-AFM modulations are due to itinerant and localized contributions to the magnetic moment, respectively. Finally, the direct measurement of the magnetic order parameter provided a value of the critical exponent \(\beta = 0.245 \approx \frac{1}{4}\), suggesting a non conventional critical behavior for the magnetic phase transition in NaCr\(_2\)O\(_4\).
In this work we present systematic set of measurements carried out by muon spin rotation/relaxation (\(\mu^+\)SR) and neutron powder diffraction (NPD) on the solid solution Na\(_{\rm x}\)Ca\(_{1- \rm ...x}\)Cr\(_2\)O\(_4\). This study investigates Na-ion dynamics in the quasi-1D (Q1D) diffusion channels created by the honeycomb-like arrangement of CrO\(_6\) octahedra, in the presence of defects introduced by Ca doping. With increasing Ca content, the size of the diffusion channels is enlarged, however, this effect does not enhance the Na ion mobility. Instead the overall diffusivity is hampered by the local defects and the Na hopping probability is lowered. The diffusion mechanism in Na\(_{\rm x}\)Ca\(_{1- \rm x}\)Cr\(_2\)O\(_4\) was found to be interstitial and the activation energy as well as diffusion coefficient were determined for all the members of the solid solution.
The molecular mechanisms responsible for the high immunosuppressive capacity of CD4+ Tregs in tumors are not well known. High-dimensional single-cell profiling of T cells from chemotherapy-naive ...individuals with non-small-cell lung cancer identified the transcription factor IRF4 as specifically expressed by a subset of intratumoral CD4+ effector Tregs with superior suppressive activity. In contrast to the IRF4- counterparts, IRF4+ Tregs expressed a vast array of suppressive molecules, and their presence correlated with multiple exhausted subpopulations of T cells. Integration of transcriptomic and epigenomic data revealed that IRF4, either alone or in combination with its partner BATF, directly controlled a molecular program responsible for immunosuppression in tumors. Accordingly, deletion of Irf4 exclusively in Tregs resulted in delayed tumor growth in mice while the abundance of IRF4+ Tregs correlated with poor prognosis in patients with multiple human cancers. Thus, a common mechanism underlies immunosuppression in the tumor microenvironment irrespective of the tumor type.
CD8
T cells infiltrating tumors are largely dysfunctional, but whether a subset maintains superior functionality remains ill defined. By high-dimensional single cell analysis of millions of CD8
T ...cells from 53 individuals with lung cancer, we defined those subsets that are enriched in tumors compared with cancer-free tissues and blood. Besides exhausted and activated cells, we identified CXCR5
TIM-3
CD8
T cells with a partial exhausted phenotype, while retaining gene networks responsible for stem-like plasticity and cytotoxicity, as revealed by single cell sequencing of the whole transcriptome. Ex vivo, CXCR5
TIM-3
CD8
T cells displayed enhanced self-renewal and multipotency compared with more differentiated subsets and were largely polyfunctional. Analysis of inhibitory and costimulatory receptors revealed PD-1, TIGIT, and CD27 as possible targets of immunotherapy. We thus demonstrate a hierarchy of differentiation in the context of T cell exhaustion in human cancer similar to that of chronically infected mice, which is further shown to disappear with disease progression.
T cell memory relies on the generation of antigen-specific progenitors with stem-like properties. However, the identity of these progenitors has remained unclear, precluding a full understanding of ...the differentiation trajectories that underpin the heterogeneity of antigen-experienced T cells. We used a systematic approach guided by single-cell RNA-sequencing data to map the organizational structure of the human CD8
memory T cell pool under physiological conditions. We identified two previously unrecognized subsets of clonally, epigenetically, functionally, phenotypically and transcriptionally distinct stem-like CD8
memory T cells. Progenitors lacking the inhibitory receptors programmed death-1 (PD-1) and T cell immunoreceptor with Ig and ITIM domains (TIGIT) were committed to a functional lineage, whereas progenitors expressing PD-1 and TIGIT were committed to a dysfunctional, exhausted-like lineage. Collectively, these data reveal the existence of parallel differentiation programs in the human CD8
memory T cell pool, with potentially broad implications for the development of immunotherapies and vaccines.
COVID-19 survivors are at increased risk of persistent psychopathology after the infection. Despite long-term sequelae are an increasing concern, long-term neuropsychiatric consequences remain ...largely unclear. This cohort study aimed at investigating the psychopathological impact of COVID-19 in Italy one year after infection, outlining the trajectory of symptomatology at one, six-, and twelve-months follow-up.
We evaluated 402, 216, and 192 COVID-19 survivors respectively at one, six, and 12 months. A subgroup of 95 patients was evaluated longitudinally both at one, six, and 12 months. Validated self-report questionnaires were administered to assess depression, fatigue, anxiety, and post-traumatic distress. Socio-demographics and setting of care information were gathered for each participant.
At six and twelve months, respectively 94 (44%) and 86 (45%) patients self-rated in the clinical range in at least one psychopathological dimension. Pathological fatigue at twelve months was detected in 63 patients (33%). Considering the longitudinal cohort an interaction effect of sex and time was observed for depression (F = 8.63, p < 0.001) and anxiety (F = 5.42, p = 0.005) with males showing a significant increasing trend of symptoms, whereas an opposite course was observed in females.
High prevalence of psychiatric sequelae six and 12 months after COVID-19 was reported for the first time. These findings confirm the need to provide integrated multidisciplinary services to properly address long-lasting mental health sequelae of COVID-19 and to treat them with the aim of reducing the disease burden and related years of life lived with disability.
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