Bridge Formation Research Articles

Development of Static Fluid Demonstrators: Hydraulic Bridge to Improve Laboratory Skills

Abstract This research aims to develop a hydraulic bridge as a static fluid material prop. The development of these teaching aids focuses on improving students’ laboratory skills. This research is based on the need for students to have practical experience in the laboratory. This developed hydraulic bridge prop is expected to strengthen mastery of concepts in static fluid materials and improve students’ laboratory skills. The research method used is research and development with the resulting product in the form of hydraulic bridge props. Quantitative analysis techniques are used to measure the feasibility and effectiveness of teaching aids that have been developed, as well as to improve students’ laboratory skills. The results showed that the hydraulic bridge trainers that have been developed have excellent feasibility and effectiveness. The results showed a positive relationship between using hydraulic bridge props and improving student laboratory capabilities. The interactive nature of the developed teaching aids enhances technical abilities and fosters students’ critical thinking, problem-solving, and teamwork skills. This study concluded that the teaching aids in the form of hydraulic bridges that had been developed proved feasible and effective and were able to improve students’ laboratory skills. The implications of this research extend to curriculum improvement and advocating for the integration of practical teaching aids, such as hydraulic bridges, to optimize student learning outcomes. Future directions include improving the implementation of hydraulic bridges across engineering disciplines and conducting longitudinal studies to assess its long-term impact on student’s academic and professional development.

Incorporating Microbial Stimuli for Osteogenesis in a Rabbit Posterolateral Spinal Fusion Model.

Autologous bone grafts are commonly used to repair defects in skeletal tissue, however, due to their limited supply there is a clinical need for alternatives. Synthetic ceramics present a promising option but currently lack biological activity to stimulate bone regeneration. One potential approach to address this limitation is the incorporation of immunomodulatory agents. In this study, we investigate the application of microbial stimuli to stimulate bone formation. Three different microbial stimuli were incorporated in a biphasic calcium phosphate (BCP) ceramic: Bacille Calmette-Guérin (BCG), gamma-irradiated Staphylococcus aureus (γi-S. aureus), or Candida albicans (γi-C. Albicans). The constructs were then implanted in both a rabbit posterolateral spinal fusion (PLF) and an intramuscular implant model for 10 weeks and compared to a non-stimulated control construct. For the PLF model, the formation of a bony bridge was evaluated by manual palpation, micro-CT, and histology. While complete fusion was not observed, the BCG condition was most promising with higher manual stiffness and almost twice as much bone volume in the central fusion mass compared to the control (9±4.4% bone area vs 4.6±2.3%, respectively). Conversely, the γi-S. aureus or γi-C. albicans appeared to inhibit bone formation (1.4±1.4% and 1.2±0.6% bone area). Bone induction was not observed in any of the intramuscular implants. This study indicates that incorporating immunomodulatory agents in ceramic bone substitutes can affect bone formation, which can be positive when selected carefully. The readily available and clinically approved BCG showed promising results, which warrants further research for clinical translation.

Capturing Autoinhibited PDK1 Reveals the Linker's Regulatory Role, Informing Innovative Inhibitor Design.

PDK1 is crucial for PI3K/AKT/mTOR and Ras/MAPK cancer signaling. It phosphorylates AKT in a PIP3-dependent but S6K, SGK, and RSK kinases in a PIP3-independent manner. Unlike its substrates, its autoinhibited monomeric state has been unclear, likely due to its low population time, and phosphorylation in the absence of PIP3 has been puzzling too. Here, guided by experimental data, we constructed models and performed all-atom molecular dynamics simulations. In the autoinhibited PDK1 conformation that resembles autoinhibited AKT, binding of the linker between the kinase and PH domains to the PIF-binding pocket promotes the formation of the Glu130-Lys111 salt bridge and weakens the association of the kinase domain with the PH domain, shifting the population from the autoinhibited state to states accessible to the membrane and its kinase substrates. The interaction of the substrates' hydrophobic motif and the PDK1 PIF-binding pocket facilitates the release of the autoinhibition even in the absence of PIP3. Phosphorylation of the serine-rich motif within the linker further attenuates the association of the PH domain with the kinase domain. These suggest that while the monomeric autoinhibited state is relatively stable, it can readily shift to its active, catalysis-prone state to phosphorylate its diverse substrates. Our findings reveal the PDK1 activation mechanism and discover the regulatory role of PDK1's linker, which lead to two innovative linker-based inhibitor strategies: (i) locking the autoinhibited PDK1 through optimization of the interactions of AKT inhibitors with the PH domain of PDK1 and (ii) analogs (small molecules or peptidomimetics) that mimic the linker interactions with the PIF-binding pocket.

Viral Infections and Their Ability to Modulate Endoplasmic Reticulum Stress Response Pathways.

In eukaryotic cells, the endoplasmic reticulum is particularly important in post-translational modification of proteins before they are released extracellularly or sent to another endomembrane system. The correct three-dimensional folding of most proteins occurs in the ER lumen, which has an oxidative environment that is essential for the formation of disulfide bridges, which are important in maintaining protein structure. The ER is a versatile organelle that ensures the correct structure of proteins and is essential in the synthesis of lipids and sterols, in addition to offering support in the maintenance of intracellular calcium. Consequently, the cells needed to respond to demands caused by physiological conditions and pathological disturbances in the organelle homeostasis, leading to proper functioning of the cell or even programmed cell death. Disturbances to the ER function trigger a response to the accumulation of unfolded or misfolded proteins, known as the unfolded protein response. Such disturbances include abiotic stress, pharmacological agents, and intracellular pathogens, such as viruses. When misfolded proteins accumulate in the ER, they can undergo ubiquitination and proteasomal degradation through components of the ER-associated degradation system. Once a prolonged activity of the UPR pathway occurs, indicating that homeostasis cannot be reestablished, components of this pathway induce cell death by apoptosis. Here, we discuss how viruses have evolved ways to counteract UPR responses to maximize replication. This evolutionary viral ability is important to understand cell pathology and should be taken into account when designing therapeutic interventions and vaccines.

Microscale insights into deep bed membrane filtration: Influence of internal surface roughness

Deep bed filtration is widely applied in bioprocessing, virus filtration, and water purification to remove small impurities, such as particles or virus fragments. However, more needs to be understood about the parameters that influence particle capture and deposition. Detailed simulations and microfluidic filtration experiments with straight pores have been widely investigated, yet realistic membrane porosity features such as pore gradients and roughness have not been addressed in detail. The internal membrane morphology is assumed to have a strong effect on filtration performance. Therefore, this study introduces a new microfluidic membrane mimicking device (MMD) and methodology that analyzes spatio-temporal particle collections in a deep bed filtration MMD with gradually decreasing pore size toward the retentate side. The design allows us to systematically tailor an internal filter surface roughness to investigate its influence on differently sized soft particles and the consequences for filtration performance, in particular, particle capture. Optical investigation and quantitative evaluation show enhanced particle–pillar interactions for increased roughness. This results in a reduced penetration depth and reduced particle breakthrough. The modes of capture or filtration phenomena, such as pore blocking, bridging, or dendrite formation, differ significantly between smooth and rough membrane filter structures. In the case of rough inner filter surfaces, those phenomena lead to a less distinct decrease in volumetric flow, allowing a longer filtration process. The microfluidic study offers a detailed investigation of how microscale phenomena influence the filtration process. The results provide a fundamental understanding of microscale filtration effects based on roughness and, hence, motivate a tailoring of the internal membrane filter surface according to the filtration problem at hand.

Development of low oil emulsion gels by solidification of oil droplets and determination of their rheological properties

This study aims to develop low-fat emulsion gels by physically solidifying oil droplets using a combination of pectin, soy protein, and bovine gelatin, and to investigate the rheological properties of these emulsion gels. The emulsion gels were formulated with different combinations of these biopolymers [PSG30 (pectin + soy protein + gelatin + 30% oil), PS30 (pectin + soy protein + 30% oil), P30 (pectin + 30% oil), G30 (gelatin + 30% oil)] and compared with commercially available low-fat mayonnaise (DYM40, 40% oil), mayonnaise (TM80, 80% oil), and spreadable fat (SY59, 59% oil) samples. The consistency index (K, Pa.sn) of the emulsion gels ranged from 1.903 to 150.739 Pa.sn, with PSG30 and PS30 formulations exhibiting higher K values than the commercial samples. The highest structural recovery percentage was observed in the SY59 sample at 114.91%. Thermal stability tests demonstrated that PSG30 and PS30 maintained their viscosity and storage modulus (G') values over a wide temperature range. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed significant hydrogen bonding and cross-linking interactions between pectin, soy protein, and gelatin. Microstructural imaging showed that PSG30 had the most homogeneous structure, consistent with its superior rheological performance. Molecular docking analysis determined the binding energy between gelatin and pectin to be -6.40 kcal/mol. Interaction between pectin (Arg-522 residue) and soy protein (11S globulin TGT) was facilitated by salt bridge formation. The developed formulations of pectin, soy protein, and gelatin demonstrate potential for producing low-fat emulsion gels with acceptable texture and stability properties for various food applications.

Calcium phosphate complex of recombinant human thrombomodulin promote bone formation in interbody fusion.

Interbody fusion is an orthopedic surgical procedure to connect two adjacent vertebrae in patients suffering from spinal disc disease. The combination of synthetic bone grafts with protein-based drugs is an intriguing approach to stimulate interbody bone growth, specifically in patients exhibiting restricted bone progression. Recombinant human thrombomodulin (rhTM), a novel protein drug characterized by its superior stability and potency, shows promise in enhancing bone formation. A composite bone graft, termed CaP-rhTM, has been synthesized, combining calcium phosphate (CaP) microparticles as a delivery vehicle for rhTM to facilitate interbody fusion. In vitro studies have demonstrated that rhTM significantly promotes the proliferation and maturation of preosteoblasts at nanogram dosage, while exerting minimal impact on osteosarcoma cell growth. The expression levels of mature osteoblast markers, including osteocalcin, osteopontin, alkaline phosphatase, and calcium deposition were also enhanced by rhTM. In rat caudal disc model of interbody fusion, CaP-rhTM with 800 ng of drug doaeage was implanted along with a polylactic acid (PLA) cage, to ensure structural stability within the intervertebral space. Microcomputed tomography analyses revealed that from 8 to 24 weeks, CaP-rhTM substantially improves both bone volume and trabecular architecture, in addition to the textural integrity of bony endplate surfaces. Histological examination confirmed the formation of a continuous bone bridge connecting adjacent vertebrae. Furthermore, biomechanical assessment via three-point bending tests indicated an improved bone quality of the fused disc. This study has demostrated that rhTM exhibits considerable potential in promoting osteogenesis. The use of CaP-rhTM has also shown significant improvements in promoting interbody fusion.

During Postnatal Ontogenesis, the Development of a Microvascular Bed in an Intestinal Villus Depends on Intussusceptive Angiogenesis.

The mechanisms responsible for the growth and development of vascular beds in intestinal villi during postnatal ontogenesis remain enigmatic. For instance, according to the current consensus, in the sprouting type of angiogenesis, there is no blood flow in the rising capillary sprout. However, it is known that biomechanical forces resulting from blood flow play a key role in these processes. Here, we present evidence for the existence of the intussusception type of angiogenesis during the postnatal development of micro-vessel patterns in the intestinal villi of rats. This process is based on the high-level flattening of blood capillaries on the flat surfaces of intestinal villi, contacts among the opposite apical plasma membrane of endothelial cells in the area of inter-endothelial contacts, or the formation of bridges composed of blood leucocytes or local microthrombi. We identified factors that, in our opinion, ensure the splitting of the capillary lumen and the formation of two parallel vessels. These phenomena are in agreement with previously described features of intussusception angiogenesis.

Crystal structure of a Clostridioides difficile multiple antibiotic resistance regulator (MarR) CD0473 suggests a potential redox-regulated function

Clostridioides difficile may constitute a small part of normal gut microbiota in humans without causing any symptoms, but an uncontrolled growth common to hospitalized patients can cause Clostridioides difficile infection (CDI) leading to severe colonic symptoms. As the bacteria are attaining resistance to various antibiotics worldwide, CDI is becoming a serious public health problem. Although a family of transcription factors called MarR (Multiple antibiotic resistance Regulator) plays a key role in the bacterial response to various environmental stresses including antibiotics, most of the 14 MarRs predicted to exist in the C. difficile genome lack structural or functional studies. In this respect, X-ray crystal structure of a C. difficile MarR CD0473 with a yet unknown function has been determined using a Hg-soaked crystal. In the structure, two closely located flexible conformations of Hg-bound cysteines suggested a possibility of intra-subunit disulfide bridge formation. By searching the neighboring intergenic regions of CD0473, two pseudo-palindromic DNA sites were found and shown to bind the protein. MarR CD0473 binding stronger to the DNA in an oxidizing condition supported further that it may function as a redox regulated switch likely via its oxidized disulfide formation.

Bottlebrush Midblocks Promote Colloidal Bridging of Telechelic Polymers.

Telechelic polymers are effective rheological modifiers that bridge between associative constituents to form elastic networks. The performance of linear telechelic chains, however, is controlled by entropic forces and thus suffers from an upper limit on bridge formation. This work overcomes this limitation by utilizing telechelic triblock copolymers containing bottlebrush midblocks. By comparing the rheological properties of emulsions linked by telechelic bottlebrush polymers to those containing linear chains, we determined that telechelic polymers with bottlebrush midblocks form elastic networks more efficiently. These enhanced rheological properties arise from the high stiffness of the bottlebrush midblocks, which offsets the entropic stretching penalty for bridge formation, enabling them to more readily form networks. This molecular-level control over polymer conformation in complex fluids opens avenues for designing highly elastic networks with minimal polymeric additives.

Preoperative Factors on Loss of Range of Motion after Posterior Cervical Foraminotomy.

Background and Objectives: Posterior cervical foraminotomy (PCF) aims to resolve cervical radiculopathy while preserving range of motion (ROM). However, its effectiveness in maintaining ROM is uncertain. This study investigates the changes in ROM after PCF and identifies preoperative factors that influence ROM reduction post surgery. Materials and Methods: This retrospective cohort study included patients treated at our hospital from August 2016 to September 2021. Clinical outcomes were assessed using the visual analog scale (VAS) for neck and arm pain and the neck disability index (NDI). Radiological outcomes included the segmental angle (SA), cervical angle (CA), C2-C7 SVA, Pfirrmann grade, extent of facetectomy, foraminal stenosis, and ROM. Patients were categorized into two groups based on segmental ROM changes: decreased (Group D) and maintained (Group M). Radiological and clinical outcomes were compared between the groups. Univariate and multivariate regression analyses were performed to identify risk factors for ROM loss after PCF. Results: 76 patients were included: 34 in Group D and 42 in Group M, with no demographic differences. Preoperatively, Group D had significantly larger flexion segmental and cervical angles than Group M (segmental, p < 0.001; cervical, p = 0.001). Group D also had a higher Pfirrmann grade (p = 0.014) and more bony bridge formations (p = 0.004). While no significant differences were observed in arm pain VAS and NDI scores, Group D exhibited worse neck pain VAS at the last follow-up (p = 0.03). Univariate linear regression indicated that preoperative segmental ROM (p < 0.001, B = 0.82) and bony bridge formation (p = 0.046, B = 5.33) were significant predictors of ROM loss post PCF. Conclusions: Patients with higher preoperative flexion angles and Pfirrmann grades at the operative level are at an increased risk for ROM loss and neck pain and often exhibit bony bridge formation. Accounting for these factors can improve surgical planning and patient outcomes.

Thermal shock behavior of andalusite‐based refractories: Microstructural investigation of crack bridging and grain‐matrix interactions

AbstractAndalusite‐based refractories are characterized by superior thermal shock resistance. Although the demand for alternative raw materials is increasing, it is proving difficult to replicate the thermal shock behavior of andalusite with alternative materials. The physico‐mechanical properties of andalusite refractories are well‐studied. However, comprehensive chemical and microstructural analysis is still needed to fully understand factors influencing the thermal shock resistance. This investigation highlights the use of complementary microstructural techniques (3D digital microscopy, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, and micro‐X‐ray fluorescence) to analyze crack propagation as well as glass bridge formation and composition in aluminosilicate‐based refractory castables. Andalusite‐based refractories are compared with chamotte 45 and chamotte 60, before and after a thermal shock, as well as after an additional firing. Factors influencing the thermal shock resistance of aluminosilicate refractory castables include (1) crack shape, size, occurrence, and propagation (2) glass bridge formation, size, occurrence, and composition, and (3) aggregate‐matrix interactions.

Post-Translational Modifications to Cysteine Residues in Plant Proteins and Their Impact on the Regulation of Metabolism and Signal Transduction.

Cys is one of the least abundant amino acids in proteins. However, it is often highly conserved and is usually found in important structural and functional regions of proteins. Its unique chemical properties allow it to undergo several post-translational modifications, many of which are mediated by reactive oxygen, nitrogen, sulfur, or carbonyl species. Thus, in addition to their role in catalysis, protein stability, and metal binding, Cys residues are crucial for the redox regulation of metabolism and signal transduction. In this review, we discuss Cys post-translational modifications (PTMs) and their role in plant metabolism and signal transduction. These modifications include the oxidation of the thiol group (S-sulfenylation, S-sulfinylation and S-sulfonylation), the formation of disulfide bridges, S-glutathionylation, persulfidation, S-cyanylation S-nitrosation, S-carbonylation, S-acylation, prenylation, CoAlation, and the formation of thiohemiacetal. For each of these PTMs, we discuss the origin of the modifier, the mechanisms involved in PTM, and their reversibility. Examples of the involvement of Cys PTMs in the modulation of protein structure, function, stability, and localization are presented to highlight their importance in the regulation of plant metabolic and signaling pathways.

Mussel-Inspired Multifunctional Polyethylene Glycol Nanoparticle Interfaces.

Nanoparticles (NPs) are receiving increasing interest in biomedical applications. However, due to their large surface area, in physiological environments, they tend to interact with plasma proteins, inducing their agglomeration and ultimately resulting in a substantial efficiency decrease in diagnostic and therapeutic applications. To overcome such problems, NPs are typically coated with a layer of hydrophilic and biocompatible polymers, such as PEG chains. However, few examples exist in which this property could be systematically fine-tuned and combined with added properties, such as emission. Herein, we report a novel mussel-inspired catechol-based strategy to obtain biocompatible and multifunctional coatings, using a previously developed polymerization methodology based on the formation of disulfide bridges under mild oxidative conditions. Two families of NPs were selected as the proof of concept: mesoporous silica NPs (MSNPs), due to their stability and known applications, and magnetite NPs (Fe3O4 NPs), due to their small size (<10 nm) and magnetic properties. The PEG coating confers biocompatibility on the NPs and can be further functionalized with bioactive molecules, such as glucose units, through the end carboxylic acid moieties. Once we demonstrated the feasibility of our approach to obtaining PEG-based coatings on different families of NPs, we also obtained multifunctional coatings by incorporating fluorescein functionalities. The resulting coatings not only confer biocompatibility and excellent cell internalization, but also allow for the imaging and tracking of NPs within cells.

Fusion Dynamics and Size-Dependence of Droplet Microstructure in ssDNA-Mediated Protein Phase Separation.

Biomolecular condensation involving proteins and nucleic acids has been recognized to play crucial roles in genome organization and transcriptional regulation. However, the biophysical mechanisms underlying the droplet fusion dynamics and microstructure evolution during the early stage of liquid-liquid phase separation (LLPS) remain elusive. In this work, we study the phase separation of linker histone H1, which is among the most abundant chromatin proteins, in the presence of single-stranded DNA (ssDNA) capable of forming a G-quadruplex by using molecular simulations and experimental characterization. We found that droplet fusion is a rather stochastic and kinetically controlled process. Productive fusion events are triggered by the formation of ssDNA-mediated electrostatic bridges within the droplet contacting zone. The droplet microstructure is size-dependent and evolves driven by maximizing the number of electrostatic contacts. We also showed that the folding of ssDNA to the G-quadruplex promotes LLPS by increasing the multivalency and strength of protein-DNA interactions. These findings provide deep mechanistic insights into the growth dynamics of biomolecular droplets and highlight the key role of kinetic control during the early stage of ssDNA-protein condensation.

The Central Paratethys Sea – Part of the tropical eastern Atlantic rather than gate into the Indian Ocean

The Miocene Paratethys Sea is frequently depicted as junction between the Proto-Mediterranean Sea and the Indian Ocean. Herein, we elucidate the biogeographic character of this large epicontinental Miocene sea based on its speciose gastropod fauna. We debunk the persistent myth that there was a connection between these marine realms during Langhian times via the Tethys Seaway. Throughout most of the Early and Middle Miocene the connectivity of the Central Paratethys was via the Rhône Strait and the Slovenian Strait as supported by up to ~22 % of species shared with the Proto-Mediterranean Sea. The faunistic similarity decreased successively at higher latitudes towards the northeastern Atlantic and dropped to low values towards the North Sea. Therefore, a connection with the North Sea can be excluded throughout the Early and Middle Miocene. Faunistic relations of the Central Paratethys Sea with the Eastern Paratethys Sea were surprisingly low until the late Middle Miocene, when endemic species from the Eastern Paratethys ‘flooded’ the Central Paratethys. Therefore, the effectiveness in species transfer or presence of the Carasu and Barlad straits, hypothetically connecting both seas, must be questioned for most of the Middle Miocene.The present-day gastropod faunas of the tropical eastern Atlantic (TEA) and the Indo-West Pacific Region (IWP) can be distinguished clearly by their differing faunal structure (different relative abundance of certain families). The faunas of the Paratethyan and the Proto-Mediterranean Sea follow more closely the type nowadays represented in the tropical eastern Atlantic, suggesting a common origin. The faunistic connectivity with the Indian Ocean, via the Tethys Seaway ceased very early during the Early Miocene, predating the formation of the Gomphotherium land bridge by several million years. Consequently, we reject a re-activation of the Tethys Seaway during the Langhian as providing an effective oceanographic gateway. This is an important observation for climate models, linking the closure of the Tethys Seaway to Miocene climate change.

A new neoceratopsian (Ornithischia, Ceratopsia) from the Lower Cretaceous Ohyamashimo Formation (Albian), southwestern Japan

AbstractThe herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early‐branching neoceratopsians extending their geographical range to North America sometime during the Barremian to Albian. However, the specific timing and mode of their dispersal from Asia to North America remains unknown. Here we describe a new, early‐branching neoceratopsian, Sasayamagnomus saegusai gen. et sp. nov., from the Albian Ohyamashimo Formation in southwestern Japan, representing the easternmost fossil record of ceratopsians in Asia. Sasayamagnomus exhibits three diagnostic features in the jugal, squamosal and coracoid, respectively, and also has a unique combination of characters in the lacrimal. Our phylogenetic analysis indicates that Sasayamagnomus forms a clade with Aquilops americanus, one of the earliest neoceratopsians from North America, followed by the sister taxon Auroraceratops rugosus from China. The present time‐calibrated phylogenetic tree indicates that the immigration of neoceratopsians from Asia to North America occurred during the latest Aptian or early Albian, refining the previously suggested timeframe. This aligns with fragmentary neoceratopsian fossil records from the Lower Cretaceous of North America and the initial formation of the Bering land bridge. Furthermore, the simultaneous occurrence of global warming (which enabled the development of extensive forests in the Arctic region) and the emergence of the Bering land bridge during the Aptian–Albian, probably played a crucial role in facilitating the immigration of neoceratopsians from Asia to North America.

Additively manufactured Nb-Ti-Si based alloy: As-built and heat-treated conditions

This work aims to fully characterise the Nb-Ti-Si based alloy (Nb-26Ti-16Si-2.2Al-2Cr), processed by the electron-beam powder-bed-fusion in both as-built and heat-treated conditions, to elucidate the microstructure-property relationships. The as-built condition has [001]-oriented columnar grains of the Nb3Si phase with the Nbss phase dispersed throughout the microstructure. The microhardness is 645.2 ± 6.7 HV0.5, and the indentation fracture toughness shows distinct directionality: 7.7 MPa·m1/2 in the horizontal direction compared to 5.3 MPa·m1/2 in the vertical direction. Both properties are comparable to the cast version. The directionality is attributed to the underlying mechanisms such as crack bridging, arrest, and micro-crack formation. By contrast, in the heat-treated condition, the alloy exhibits a dual-phase microstructure (Nbss and Nb5Si3 phases) with near-equiaxed grain shape due to the Nb3Si phase decomposition. The fracture toughness increases to 12.1 MPa·m1/2, at the expense of a reduced microhardness of 564.4 ± 15.0 HV0.5.

Microtomographic and histological evaluation of two bioceramics as pulp capping agents in vivo.

Maintaining pulp vitality and function is a priority of the medicaments employed in pulp therapy to preserve tooth integrity. Aim: This study evaluated inflammatory response and reparative dentin bridge formation after direct pulp capping with two different bioceramics. Materials and Method: This was an in vivo controlled experimental study on 12 male Wistar rats. Pulpotomies were performed and the exposed pulps were capped with Biodentine or Neo MTA. After 15, 45 and 90 days, maxillary segments were obtained and prepared for histologic analysis and Micro-CT. Hounsfield Units (HU) were quantified. Results: Micro-CT analysis showed greater mineralization at 90 days with Neo MTA than with Biodentine. HU did not differ significantly (p >0.05) between molars treated with Biodentine and Neo MTA at 15 and 45 days, but at 90 days, there was statistically significant difference (p <0.05) between them. Reparative dentin was observed near the pulp exposure and canal orifice with both bioceramics. At 45 and 90 days, molars treated with Neo MTA showed mineralized tissue filling the canal orifice. Molars treated with Biodentine showed mineralized tissue and dentin bridge at the site of exposure at 45 days, and total pulp exposure coverage and mineralized entin matrix at 90 days. Conclusions: Biodentine and Neo MTA induce the formation of reparative dentin bridge after 45 days with inflammatory cell infiltrate.

Effect of ash-bridge deposition in asymmetric diesel particulate filter channels on the pressure drop and particulate matter trapping characteristics

A diesel particulate filter (DPF) is commonly used to trap particulate matter (PM). The collapse and sintering of carbon and ash deposits during exhaust gas flow and DPF regeneration frequently result in the formation of ash bridges, which are buildups of ash and PM that clog the filter channels. To investigate the impact of an ash bridge formed by accumulated ash on the pressure drop and PM trapping characteristics of asymmetric DPFs, an asymmetric DPF channel with an ash bridge was constructed. The analysis employed computational fluid dynamics to examine how the ash bridge affects the pressure drop and PM trapping characteristics in an asymmetric DPF. This study reveals that the asymmetric DPF design effectively enhances the ash-holding capacity, thereby mitigating the risk of channel blockage. The presence of ash bridges in DPF channels has a more substantial impact on the pressure drop through radial congestion than through axial congestion. The application of asymmetric thin-wall DPFs can counteract the increase in exhaust backpressure caused by ash bridges. An ash bridge located in the middle of a DPF channel intensifies the uneven deposition of PM. However, implementing an asymmetric DPF structure enhances the uniformity of PM deposition.