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Topic Review
Thermal Load and Heat Transfer in Dental Implants
Heat is a kinetic process whereby energy flows from between two systems, hot-to-cold objects. In oro-dental implantology, conductive heat transfer/(or thermal stress) is a complex physical phenomenon to analyze and consider in treatment planning. Hence, ample research has attempted to measure heat-production to avoid over-heating during bone-cutting and drilling for titanium (Ti) implant-site preparation and insertion, thereby preventing/minimizing early (as well as delayed) implant-related complications and failure. The goal is two-fold: (A) the standard heat equation is proposed to be solved, modifying the imposed boundary conditions without any additional source term, and on the other hand, (B) a gap is filled in the literature via obtaining an exact analytical solution of a somewhat simplified problem, which nevertheless, encapsulates the physics and reproduces the results already found in previous works via numerical analyses. In addition, for the first time, the intrinsic time is introduced and involved herein, a “proper” time that characterizes the geometry of the dental implant fixture and overall system, and how the interplay between that time and the exposure time influences temperature changes, and subsequent implant survival, are shown. Thus, this work aims to complement the overall clinical diagnostic and treatment plan for enhanced biological one–implant interface and mechanical implant stability and success rates, whether for immediate or delayed implant loading strategies.
  • 1.2K
  • 11 Mar 2022
Topic Review
Theoretical Evaluations for Designing/Engineering Metalloproteins
Almost half of all known proteins contain metal co-factors. Crucial for the flawless performance of a metalloprotein is the selection with high fidelity of the cognate metal cation from the surrounding biological fluids. Therefore, elucidating the factors controlling the metal binding and selectivity in metalloproteins is of particular significance. The knowledge thus acquired not only contributes to better understanding of the intimate mechanism of these events but, also, significantly enriches the researcher’s toolbox that could be used in designing/engineering novel metalloprotein structures with pre-programmed properties. A powerful tool in aid of deciphering the physical principles behind the processes of metal recognition and selectivity is theoretical modeling of metal-containing biological structures.
  • 202
  • 08 Mar 2023
Topic Review
The Physics of DNA Folding
Within cell nuclei, several biophysical processes occur in order to allow the correct activities of the genome such as transcription and gene regulation. To quantitatively investigate such processes, polymer physics models have been developed to unveil the molecular mechanisms underlying genome functions. Among these, phase-separation plays a key role since it controls gene activity and shapes chromatin spatial structure. By considering more complex polymer models, it is possible to reproduce the folding of real genomic regions, having specific, intricate contact patterns as seen, e.g., in Hi-C or GAM experiments. To this aim, it is necessary to specialize the polymer model, i.e., the attractive interaction between the polymer and binding molecules, by introducing different types of the polymer sites, each interacting with their specific cognate binders.
  • 299
  • 25 May 2022
Topic Review
The Magnetoencephalogram
In 1968, biomagnetism pioneer David Cohen performed the first measurement of the magnetic field of the brain: the magnetoencephalogram (MEG). He detected the brain’s largest signal: the alpha rhythm. This nearly sinusoidal oscillation at a frequency of about 10 Hz is turned on or off by closing or opening your eyes.
  • 430
  • 04 May 2023
Topic Review
The Gene Family of Voltage-Gated ChLoride Channels
Endosomes and lysosomes are intracellular vesicular organelles with important roles in cell functions such as protein homeostasis, clearance of extracellular material, and autophagy. Endolysosomes are characterized by an acidic luminal pH that is critical for proper function. Five members of the gene family of voltage-gated ChLoride Channels (CLC proteins) are localized to endolysosomal membranes, carrying out anion/proton exchange activity and thereby regulating pH and chloride concentration. Mutations in these vesicular CLCs cause global developmental delay, intellectual disability, various psychiatric conditions, lysosomal storage diseases, and neurodegeneration, resulting in severe pathologies or even death. 
  • 207
  • 14 Jun 2023
Topic Review
The DNA Alkyltransferase Family of DNA Repair Proteins
DNA alkyltransferase and alkyltransferase-like family proteins are responsible for the repair of highly mutagenic and cytotoxic O6-alkylguanine and O4-alkylthymine bases in DNA. Their mechanism involves binding to the damaged DNA and flipping the base out of the DNA helix into the active site pocket in the protein. Alkyltransferases then directly and irreversibly transfer the alkyl group from the base to the active site cysteine residue. In contrast, alkyltransferase-like proteins recruit nucleotide excision repair components for O6-alkylguanine elimination. One or more of these proteins are found in all kingdoms of life, and where this has been determined, their overall DNA repair mechanism is strictly conserved between organisms.
  • 233
  • 19 Jan 2024
Topic Review
The Coupling in Biological Membranes
Cell membrane structure is proposed as a lipid matrix with embedded proteins, and thus, their emerging mechanical and electrostatic properties are commanded by lipid behavior and their interconnection with the included and absorbed proteins, cytoskeleton, extracellular matrix and ionic media. Structures formed by lipids are soft, dynamic and viscoelastic, and their properties depend on the lipid composition and on the general conditions, such as temperature, pH, ionic strength and electrostatic potentials. The dielectric constant of the apolar region of the lipid bilayer contrasts with that of the polar region, which also differs from the aqueous milieu, and these changes happen in the nanometer scale. Besides, an important percentage of the lipids are anionic, and the rest are dipoles or higher multipoles, and the polar regions are highly hydrated, with these water molecules forming an active part of the membrane. Therefore, electric fields (both, internal and external) affects membrane thickness, density, tension and curvature, and conversely, mechanical deformations modify membrane electrostatics. As a consequence, interfacial electrostatics appears as a highly important parameter, affecting the membrane properties in general and mechanical features in particular.
  • 626
  • 12 Jul 2021
Topic Review
The Cell Nucleus as a Multiscale Porous Medium
Chromatin regulatory processes physically take place in the environment of the cell nucleus, which is filled with the chromosomes and a plethora of smaller biomolecules. The nucleus contains macromolecular assemblies of different sizes, from nanometer-sized protein complexes to micrometer-sized biomolecular condensates, chromosome territories, and nuclear bodies. This multiscale organization impacts the transport processes within the nuclear interior, the global mechanical properties of the nucleus, and the way the nucleus senses and reacts to mechanical stimuli. 
  • 246
  • 10 Aug 2023
Topic Review
The BIANCA Biophysical Model
Cancer ion therapy is constantly growing, thanks to its increased precision and, for heavy ions, its increased biological effectiveness (RBE) with respect to conventional photon therapy. The complex dependence of RBE on many factors demands for biophysical modelling. Up to now only the Local Effect Model (LEM), the Microdosimetric Kinetic Model (MKM) and the “mixed-beam” model are used in clinics. In this work the BIANCA biophysical model, after extensive benchmarking in vitro, was applied to develop a database predicting cell survival for different ions, energies and doses. Following interface with the FLUKA Monte Carlo transport code, for the first time BIANCA was benchmarked against in vivo data obtained by C-ion or proton irradiation of the rat spinal cord. The latter is a well-established model for CNS (Central Nervous System) late effects, which in turn are the main dose-limiting factor for head-and-neck tumors. Furthermore, these data have been considered to validate the LEM version applied in clinics. Although further benchmarking is desirable, the agreement between simulations and data suggests that BIANCA can predict RBE for C-ion or proton treatment of head-and-neck tumors. In particular, the agreement with proton data may be relevant if the current assumption of a constant proton RBE of 1.1 is revised. This work provides the bases for future benchmarking against patient data, as well as the development of other databases for specific tumor types and/or normal tissues.
  • 715
  • 02 Nov 2020
Topic Review Peer Reviewed
The Applications of Microphysiological Systems in Biomedicine: Impact on Urologic and Orthopaedic Research
Microphysiological systems (MPSs) are in vitro models that can incorporate dynamic stimuli such as flow, pressure and contraction in cell culture, enabling the formation of cellular architectures and retrieving physiological function often absent in conventional 2D-cell culture. MPS applications saw a substantial growth in recent years, drawing attention from industry as a strategy to optimize pre-clinical drug-development purposes, as well as from biomedical research, to fill a gap between in vivo and in vitro models. Several MPS platforms are now available and are employed in the development of bone and kidney complex systems for urologic and orthopaedic research. These advances have enabled, for example, the in vitro modelling of bone regeneration and renal drug secretion, and have dramatic potential to improve research into both orthopaedic and urology cancers. 
  • 1.1K
  • 16 Jun 2022
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