Strained Silicon on Silicon by Wafer Bonding and Layer Transfer from Relaxed SiGe Buffer

We report the creation of strained silicon on silicon (SSOS) substrate technology. The method uses a relaxed SiGe buffer as a template for inducing tensile strain in a Si layer, which is then bonded to another Si handle wafer. The original Si wafer and the relaxed SiGe buffer are subsequently removed, thereby transferring a strained-Si layer directly to Si substrate without intermediate SiGe or oxide layers. Complete removal of Ge from the structure was confirmed by cross-sectional transmission electron microscopy as well as secondary ion mass spectrometry. A plan-view transmission electron microscopy study of the strained-Si/Si interface reveals that the lattice-mismatch between the layers is accommodated by an orthogonal array of edge dislocations. This misfit dislocation array, which forms upon bonding, is geometrically necessary and has an average spacing of approximately 40nm, in excellent agreement with established dislocation theory. To our knowledge, this is the first study of a chemically homogeneous, yet lattice-mismatched, interface.Singapore-MIT Alliance (SMA

Augmented reality for dental implantology: a pilot clinical report of two cases

Background: Despite the limited number of articles dedicated to its use, augmented reality (AR) is an emerging technology that has shown to have increasing applications in multiple different medical sectors. These include, but are not limited to, the Maxillo-facial and Dentistry disciplines of medicine. In these medical specialties, the focus of AR technology is to achieve a more visible surgical field during an operation. Currently, this goal is brought about by an accurate display of either static or dynamic diagnostic images via the use of a visor or specific glasses. The objective of this study is to evaluate the feasibility of using a virtual display for dynamic navigation via AR. The secondary outcome is to evaluate if the use of this technology could affect the accuracy of dynamic navigation. Case presentation: Two patients, both needing implant rehabilitation in the upper premolar area, were treated with flapless surgery. Prior to the procedure itself, the position of the implant was virtually planned and placed for each of the patients using their previous scans. This placement preparation contributed to a dynamic navigation system that was displayed on AR glasses. This, in turn, allowed for the use of a computer-aided/image-guided procedure to occur. Dedicated software for surface superimposition was then used to match the planned position of the implant and the real one obtained from the postoperative scan. Accuracies, using this procedure were evaluated by way of measuring the deviation between real and planned positions of the implants. For both surgeries it was possible to proceed using the AR technology as planned. The deviations for the first implant were 0.53\u2009mm at the entry point and 0.50\u2009mm at the apical point and for the second implant were 0.46\u2009mm at the entry point and 0.48\u2009mm at the apical point. The angular deviations were respectively 3.05\ub0 and 2.19\ub0. Conclusions: From the results of this pilot study, it seems that AR can be useful in dental implantology for displaying dynamic navigation systems. While this technology did not seem to noticeably affect the accuracy of the procedure, specific software applications should further optimize the results

P-030 ACE2 receptor and its isoform short-ACE2 are expressed on human spermatozoa

STUDY QUESTION: Do human spermatozoa express angiotensin-converting enzyme 2 (ACE2) receptor? What would be its localization? SUMMARY ANSWER: Human spermatozoa express uniformly ACE2 on the sperm head and the flagellum. Moreover, the short-ACE2 isoform is concentrated on the post-acrosomal region and midpiece. WHAT IS KNOWN ALREADY: The Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) infection is generating important concerns regarding not only the possible consequences on the respiratory system, but also on other organs, including the reproductive system. ACE2 is considered the main point of entry for the SARS-CoV-2 within the cells through the binding with the spike protein on the virus surface. Furthermore, ACE2 is expressed in human testes cells including Leydig cells, Sertoli cells and spermatogonia. However, to date, the expression and location of ACE2 in mature human spermatozoa has not been investigated yet. STUDY DESIGN, SIZE, DURATION: This was an in vitro study for the evaluation of the expression and immune-localization of full-length ACE2 and its isoform, short-ACE2, in human spermatozoa. Thirthyfour non-immunized healthy normozoospermic volunteers were enrolled in the study. The study was conducted from May to December 2021. PARTICIPANTS/MATERIALS, SETTING, METHODS: Semen samples were collected by masturbation from non-immunized healthy normozoospermic voluntaries. Motile sperm suspensions were obtained by swim-up procedure. The expression of ACE2 was assessed by Western-blot analysis, while the immune-localization of ACE2 was evaluated by immune-cytochemical analysis under confocal microscopy. Flow-cytometry experiments were also performed to assess the surface protein expression on a large number of cells. MAIN RESULTS AND THE ROLE OF CHANCE: The Western-blot analysis of sperm extracts demonstrated two specific bands, one of approximately 120 KDa, corresponding to the glycosylated full-length ACE2, and a second one of approximately 52 KDa, the molecular weight of the protein recently termed short-ACE2. The immune-cytochemical analysis showed a uniformly localization of full-length ACE2 along both the sperm head and the flagellum, whereas the short isoform was preferentially located in the post-acrosomal region of the sperm head and the midpiece. At the flow cytometer, semen samples displayed a wide between-subject variability both in the percentage of ACE2-positive spermatozoa and the density of protein surface expression. LIMITATIONS, REASONS FOR CAUTION: Further studies are needed to determine whether short-ACE2 is a cleavage product from the full-length protein or if it is originated during spermatogenesis. Moreover, the role and the interaction of ACE2 with SARS-CoV-2 in human spermatozoa should be clarified to evaluate the possible impact of the virus on sperm biology. WIDER IMPLICATIONS OF THE FINDINGS: Since mature spermatozoa are transcriptionally silent and SARS-CoV-2 is an RNA virus, it is unlikely that the virus could affect sperm biology by replicating itself. Nevertheless, the potential effects related to modifications of the sperm membrane or interaction with other receptors or specific proteins cannot be ruled out. TRIAL REGISTRATION NUMBER: not applicabl

ACE2 Receptor and Its Isoform Short-ACE2 Are Expressed on Human Spermatozoa

Angiotensin-converting enzyme 2 (ACE2) is a protein widely expressed in numerous cell types, with different biological roles mainly related to the renin-angiotensin system. Recently, ACE2 has been in the spotlight due to its involvement in the SARS-CoV-2 entry into cells. There are no data available regarding the expression of ACE2 and its short-ACE2 isoform at the protein level on human spermatozoa. Here, protein expression was demonstrated by western blot and the percentage of sperm displaying surface ACE2 was assessed by flow cytometry. Immunocytochemistry assays showed that full-length ACE2 was mainly expressed in sperm midpiece, while short ACE2 was preferentially distributed on the equatorial and post-acrosomal region of the sperm head. To our knowledge, this is the first study demonstrating the expression of protein ACE2 on spermatozoa. Further studies are warranted to determine the role of ACE2 isoforms in male reproduction

26S PROTEASOME AND PKA MODULATE MAMMALIAN SPERM CAPACITATION BY CREATING AN INTEGRATED DIALOGUE: A COMPUTATIONAL ANALYSIS

Recent experimental evidence suggests the involvement of the 26S proteasome, the main protease active in eukaryotic cells, in the process that leads mammalian sperm to become fully fertile, so-called capacitation. Unfortunately, its role in male gametes signaling is still far from being completely understood. For this reason, here, we realized a computational model as an attempt to rebuild and explore 26S proteasome signaling cascade, aggregating all the molecular data available to date and realizing the Proteasome Interactome Network (PIN). Once obtained the network (i.e., a graph to represent the molecules as nodes and the interactions among them as links), we assessed its topology to infer important biological information. PIN is composed of 157 nodes, 248 links and it is characterized by a scale-free topology, following the Barabasi Albert model. In other words, it possesses a large amount of scarcely linked nodes and a small set of highly linked nodes, the hubs, which act as system controllers. This peculiar topology confers to the network relevant biological features: it is robust against random attacks, easily navigable and controllable and it is possible to infer new information from it. Indeed, the analysis of PIN showed that PKA and 26S proteasome were strongly interconnected and both were active in sperm signaling by influencing the protein phosphorylation pattern and then controlling several key events in sperm capacitation, such as membrane and cytoskeleton remodeling. In conclusion, the network model could explain many biological aspects of sperm physiology that are out of focus looking at the single molecular determinant, overcoming the reductionist approach which did not consider the complexity of molecules and their interactions. This could be helpful to identify potential diagnostic markers and therapeutic strategies concurring in explaining and approaching male infertility

First-Principles Study on Peierls Instability in Infinite Single-Row Al Wires

We present the relation between the atomic and spin-electronic structures of infinite single-row atomic wires made of Al atoms during their elongation using first-principles molecular-dynamics simulations. Our study reveals that the Peierls transition indeed occurs in the wire with magnetic ordering: it ruptures to form a trimerized structure with antiferromagnetic ordering and changes from a conductor to an insulator just before forming a linear wire of equally-spaced atoms. The formation of the trimerized wire is discussed in terms of the behavior of the $\sigma$-symmetry bands of the Al wire.Comment: 10 pages, 4 figure

Fullerene-based molecular nanobridges: A first-principles study

Building upon traditional quantum chemistry calculations, we have implemented an {\em ab-initio} method to study the electrical transport in nanocontacts. We illustrate our technique calculating the conductance of C$_{60}$ molecules connected in various ways to Al electrodes characterized at the atomic level. Central to a correct estimate of the electrical current is a precise knowledge of the local charge transfer between molecule and metal which, in turn, guarantees the correct positioning of the Fermi level with respect to the molecular orbitals. Contrary to our expectations, ballistic transport seems to occur in this system.Comment: 4 pages in two-column forma

Conspicuity and muscle-invasiveness assessment for bladder cancer using VI-RADS: a multi-reader, contrast-free MRI study to determine optimal b-values for diffusion-weighted imaging

To (1) compare bladder cancer (BC) muscle invasiveness among three b-values using a contrast-free approach based on Vesical Imaging-Reporting and Data System (VI-RADS), to (2) determine if muscle-invasiveness assessment is affected by the reader experience, and to (3) compare BC conspicuity among three b-values, qualitatively and quantitatively

Fractal analysis of microCT images of the oviduct during the estrous cycle

It is well known that the oviduct plays a key role in several events deeply related with reproduction, such as sperm storage and capacitation, gametes interactions, fertilization and early embryo development, among others. To better understand some of the interactions and process occurring withing this organ, the study of its morphological modifications is of primordial importance. To that, we adopted a microtomografy (MicroTC) modelling system and the fractal analysis that allow to explore the 3D oviductal functional anatomy, by using eight swine oviducts at different stages of the estrous cycle. MicroCT datasets were acquired by using the high-resolution 3D-imaging system Skyscan 1172G (Bruker, Kontich – Belgium). CT images were analyzed using plugin on ImageJ software (NIH, Bethesda, MD), a box-counting method was applied to calculate the Fractal dimension of the oviduct. Focusing our attention on the utero-tubal junction (involved in sperm selection) and the isthmo-ampullar junction (the fertilization site). We found that by using PCA analysis it was possible to clearly differentiate the oviduct at different cycle stage on the basis of their values for: Db for grid, lacunarity for grid, R2 for Db, Media Db, lacunarity, σ for D for Db, Max for D, Min for D. Lacunarity, Media and Max for Db have a greater influence on the analysis. The results showed that 2 principal components were associated whit the morphological changes. This information, is obtained by a fast nondestructive method, and could be very useful because this innovative approach enables the achievement a 3D model and suggest that using fractal analysis techniques can aid to better understand the modifications of oviduct anatomy that depends on the neuroendocrine axis. This innovative approach could be a start point to design 3D cell culture systems, that could be applied in human and animal assisted reproductive techniques, improving the IVF outcomes