Thermal behaviour of siliceous faujasite: further structural interpretation of negative thermal expansion

The high-temperature behaviour of siliceous faujasite (Si-Y) was investigated by in situ synchrotron Xray powder diffraction from room temperature up to 1123 K. This porous phase is remarkably stable when heated, and no phase transitions or changes in symmetry are observed. A marked negative thermal expansion (NTE), already reported in literature for a heating range from 25 to 573 K, was confirmed up to about 923 K. Above this temperature a positive thermal expansion was observed. Si-Y’s thermal behaviour was interpreted on the basis of the transverse thermal vibrations of the oxygen atoms involved in the T–O–T linkages and a series of other structural features characterizing the faujasite structure, namely the T–T distances between adjacent tetrahedral sites, the thickness of the double 6-membered rings, and the ditrigonal index of the 6-membered rings. Moreover, the thermal behaviour of several other anhydrous porous materials with NTE behaviour is discussed and compared to that of Si-Y

The cryogenic RWELL: a stable charge multiplier for dual-phase liquid-argon detectors

The operation of a cryogenic Resistive WELL (RWELL) in liquid argon vapor is reported for the first time. It comprises a Thick Gas Electron Multiplier (THGEM) structure coupled to a resistive Diamond-Like Carbon (DLC) anode deposited on an insulating substrate. The multiplier was operated at cryogenic temperature (90~K, 1.2~bar) in saturated argon vapor and characterized in terms of charge gain and electrical stability. A comparative study with standard, non-resistive THGEM (a.k.a LEM) and WELL multipliers, confirmed the RWELL advantages in terms of discharge quenching - thus superior gain and stability

Gut microbiome in pediatric acute leukemia: From predisposition to cure

The gut microbiome (GM) has emerged as a key factor in the genesis and progression of many diseases. The intestinal bacterial composition also influences treatment-related side effects and even the efficacy of oncological therapies. Acute leukemia (AL) is the most common cancer among children and the most frequent cause of cancer-related death during childhood. Outcomes have improved considerably over the past 4 decades, with the current long-term survival for acute lymphoblastic leukemia being ∼90%. However, several acute toxicities and long-term sequelae are associated with the multimodal therapy protocols applied in these patients. Specific GM configurations could contribute to the multistep developmental hypothesis for leukemogenesis. Moreover, GM alterations occur during the AL therapeutic course and are associated with treatment-related complications, especially during hematopoietic stem cell transplantation. The GM perturbation could last even after the removal of microbiome-modifying factors, like antibiotics, chemotherapeutic drugs, or alloimmune reactions, contributing to several health-related issues in AL survivors. The purpose of this article is to provide a comprehensive review of the chronological changes of GM in children with AL, from predisposition to cure. The underpinning biological processes and the potential interventions to modulate the GM toward a potentially health-promoting configuration are also highlighted

The Glasgow-Maastricht foot model, evaluation of a 26 segment kinematic model of the foot

BACKGROUND: Accurately measuring of intrinsic foot kinematics using skin mounted markers is difficult, limited in part by the physical dimensions of the foot. Existing kinematic foot models solve this problem by combining multiple bones into idealized rigid segments. This study presents a novel foot model that allows the motion of the 26 bones to be individually estimated via a combination of partial joint constraints and coupling the motion of separate joints using kinematic rhythms. METHODS: Segmented CT data from one healthy subject was used to create a template Glasgow-Maastricht foot model (GM-model). Following this, the template was scaled to produce subject-specific models for five additional healthy participants using a surface scan of the foot and ankle. Forty-three skin mounted markers, mainly positioned around the foot and ankle, were used to capture the stance phase of the right foot of the six healthy participants during walking. The GM-model was then applied to calculate the intrinsic foot kinematics. RESULTS: Distinct motion patterns where found for all joints. The variability in outcome depended on the location of the joint, with reasonable results for sagittal plane motions and poor results for transverse plane motions. CONCLUSIONS: The results of the GM-model were comparable with existing literature, including bone pin studies, with respect to the range of motion, motion pattern and timing of the motion in the studied joints. This novel model is the most complete kinematic model to date. Further evaluation of the model is warranted

Novel resistive charge-multipliers for dual-phase LAr-TPCs: towards stable operation at higher gains

Cryogenic versions of Resistive WELL (RWELL) and Resistive Plate WELL (RPWELL) detectors have been developed, aimed at stable avalanche multiplication of ionization electrons in dual-phase TPCs. In the RWELL, a thin resistive layer deposited on top of an insulator is inserted in between the electron multiplier (THGEM) and the readout anode; in the RPWELL, a resistive plate is directly coupled to the THGEM. Radiation-induced ionization electrons in the liquid are extracted into the gaseous phase. They drift into the THGEM's holes where they undergo charge multiplication. Embedding resistive materials into the multiplier proved to enhance operation stability due to the mitigation of electrical discharges - thus allowing operation at higher charge gain compared to standard THGEM (a.k.a. LEM) multipliers. We present the detector concepts and report on the main preliminary results

Comparison of Bone Segmentation Software over Different Anatomical Parts

Three-dimensional bone shape reconstruction is a fundamental step for any subject-specific musculo-skeletal model. Typically, medical images are processed to reconstruct bone surfaces via slice-by-slice contour identification. Freeware software packages are available, but commercial ones must be used for the necessary certification in clinics. The commercial software packages also imply expensive hardware and demanding training, but offer valuable tools. The aim of the present work is to report the performance of five commercial software packages (Mimics®, Amira™, D2P™, Simpleware™, and Segment 3D Print™), particularly the time to import and to create the model, the number of triangles of the mesh, and the STL file size. DICOM files of three different computed tomography scans from five different human anatomical areas were utilized for bone shape reconstruction by using each of these packages. The same operator and the same hosting hardware were used for these analyses. The computational time was found to be different between the packages analyzed, probably because of the pre-processing implied in this operation. The longer “time-to-import” observed in one software is likely due to the volume rendering during uploading. A similar number of triangles per megabyte (approximately 20 thousand) was observed for the five commercial packages. The present work showed the good performance of these software packages, with the main features being better than those analyzed previously in freeware packages

Are Induced Pluripotent Stem Cells a Step towards Modeling Pediatric Leukemias?

Despite enormous improvements in pre-clinical and clinical research, acute leukemia still represents an open challenge for pediatric hematologists; both for a significant relapse rate and for long term therapy-related sequelae. In this context, the use of an innovative technology, such as induced pluripotent stem cells (iPSCs), allows to finely reproduce the primary features of the malignancy and can be exploited as a model to study the onset and development of leukemia in vitro. The aim of this review is to explore the recent literature describing iPSCs as a key tool to study different types of hematological malignancies, comprising acute myeloid leukemia, non-down syndrome acute megakaryoblastic leukemia, B cell acute lymphoblastic leukemia, and juvenile myelomonocytic leukemia. This model demonstrates a positive impact on pediatric hematological diseases, especially in those affecting infants whose onsets is found in fetal hematopoiesis. This evidence highlights the importance of achieving an in vitro representation of the human embryonic hematopoietic development and timing-specific modifications, either genetic or epigenetic. Moreover, further insights into clonal evolution studies shed light in the way of a new precision medicine era, where patient-oriented decisions and therapies could further improve the outcome of pediatric cases. Nonetheless, we will also discuss here the difficulties and limitations of this model