Molar Surface Research Articles

The Optimal Parameter for Coating ZnO Nanoparticle on Orthodontic Molar Tube by Electrophoretic Deposition Method (An Invitro Study)

The fixed orthodontic appliance may enhance devious pathogens and increase biofilm accumulation around the orthodontic molar tube (OMT) surface, which may cause demineralization of the tooth surface. However, the stainless-steel OMT coated with ZnO nanoparticles may enhance antimicrobial efficacy and reduce biofilm accretion. The study aimed to identify the optimal parameter for coating orthodontic molar tubes with antimicrobial ZnO nanoparticles by the electrophoretic deposition (EPD)cell. 36 orthodontic molar tubes were included in this study. The coating process was carried out using an EPD cell. Various concentrations (7.5, 10, 20, 33) g/L of ZnO nanoparticles suspension were conducted in this study, in addition to multiple times and voltages. After the coating process, the samples were left to dry for 24 hours at room temperature. To confirm the coating and adhesion a qualitative tape test and the Scanning Electron microscope were used to study the morphological, topographical, and surface characteristics and the size of nanoparticles on the surface of the coated OMT. The innovative ZnO nanoparticles exhibit promising antibacterial properties against oral pathogens, leading to a decrease in plaque buildup, which may decrease tooth cavities and gingival irritation through orthodontic treatment. There was an increase in nanoparticle surface adhesion on the orthodontic molar tube surface at 2 mins deposition time while reduced surface adhesion as increased deposing time. The coating process was verified at a currency voltage of 30V, reducing nanoparticle agglomeration. A concentration of 10g/L of ZnO suspension shows the most stable and homogenous suspension.

An experimental-computational study on thermodynamic properties and intermolecular interactions of binary mixtures composed of quaternary ammonium salts-based deep eutectic solvents and [ETN] or [ACN]

To deep understand the thermodynamic properties and intermolecular interactions of quaternary ammonium salts-based deep eutectic solvents (DESs), two novel DESs systems ([TPAB]:[MA] and [TBAB]:[MA]) were synthesized using tetrapropylammonium bromide ([TPAB]) or tetrabutylammonium bromide ([TBAB]) as hydrogen bond acceptor (HBA) and malonic acid ([MA]) as hydrogen bond donor (HBD). Then, the ethanol (ETN) and acetonitrile (ACN) were used to prepare four DESs + solvent mixtures. Based on experimental data of density and surface tension of these four binary mixtures, the thermodynamic parameters such as apparent molar volume (Vϕ), excess molar volume (VE), limiting apparent molar expansibility (E0ϕ), molar surface entropy (s), molar surface Gibbs energy (gs), and molar surface enthalpy (h) were calculated. At the same temperature, the calculated VE values of binary mixtures were arranged in the following sequence: [TBAB]:[MA] + [ETN] > [TPAB]:[MA] + [ETN] > [TPAB]:[MA] + [ACN] > [TBAB]:[MA] + [ACN]. Based on the radial distribution functions (RDFs) theory, this observed phenomenon was attributed to the enhanced interaction between HBA and [ETN] in the DESs + [ETN] as compared to the interaction between HBA and [ACN] in the DESs + [ACN]. The predicted surface tension values (γ(pre)) of the four binary mixtures were calculated and highly correlated with the experimental surface tension values (γ(exp)). Moreover, the Br1 atom in [TPAB], the Br2 atom in [TBAB], and the H9 atom in [MA] were selected as reference sites. The interaction strength sequence between HBD and HBA was investigated using RDFs as follows: [TBAB]:[MA] + [ACN] > [TPAB]:[MA] + [ACN] > [TBAB]:[MA] + [ETN] > [TPAB]:[MA] + [ETN]. This study can provide an important theoretical support for further utilization of quaternary ammonium salts-based DESs.

Studies on interactions of L-glutamic acid with L-arabinose/D-xylose in aqueous medium: Ultrasonic velocity and acoustic parameter studies supported by FTIR spectroscopic investigation

Glutamic acid is a non-essential amino acid, meaning that the body can synthesize it on its own, and it doesn’t necessarily need to be obtained from the diet. Using an ultrasonic interferometer, the ultrasonic velocity at 293.15 K and 298.15 K and at experimental pressure P = 101 kPa were determined in order to evaluate and comprehend the synergy between non-essential amino acid and saccharides (L-arabinose/D-xylose) in an aqueous system. There is a direct correlation between the weak and strong molecular interactions that occur between the solution’s constituents and the propagation of ultrasonic sound waves through the experimental solutions. Using the ultrasonic velocity data, isentropic compressibility (Ks) apparent molar isentropic compressibility (Ks,ϕ) and isothermal compressibility (KT) were calculated. In addition to these characteristics, acoustic impedance (Z), internal pressure (πi), relative association (RA), molar free volume (Vf), molar free length (Lf) and surface tension (γ) were deduced and analysed to advocates potent ion- solvent interactions. In order to gain understanding of Glu-Glu and Glu- L-arabinose/D-xylose interactions in aqueous medium, these parameters were interpreted. Ion-solvent interactions are stronger than ion-ion interactions due to the greater and positive values of Ks0. Strong contacts occur between the polar segments of L-arabinose/D-xylose and the zwitterionic groups of Glu, and these interactions become stronger as the concentration of L-arabinose/D-xylose increases, as indicated by positive values of Ks,ϕ,tr0. The water structure is reformed during the solvation and ion association processes of Glu. Furthermore, the spectroscopic investigation has been conducted using the FTIR technique in order to verify the results obtained from acoustic studies. Predominant ion-hydrophilic/hydrophobic interactions prevail in the studied system is validated by FTIR study. Absorption band widening indicates that intermolecular hydrogen bonding predominates over intramolecular hydrogen bonding.

Designing Robust CdS Nanostructures for Superior Photostability and Enhanced Photocatalytic Degradation of Organic Pollutants

AbstractTill date it is a great challenge to synthesize CdS photocatalyst with a high stability. In this study, a stable CdS photocatalyst was successfully synthesized by a simple, cost‐effective hydrothermal route via cadmium acetate and thiourea as Cd and S precursors, respectively. The effect of different processing times (8 h and 24 h) and molar ratios on the photocatalytic activity and stability were mainly investigated. The samples were characterized in detail by XRD, FT‐IR, XPS, UV‐vis DRS, Photolummiscence spectroscopy and Surface photovoltage. The photocatalytic activity of the as‐obtained nanostructures was examined for methylene blue (MB) dye degradation under visible light irradiation (λ≥420 nm). After 70 min of irradiation, nearly 82 % of MB was degraded by CdS nanostructures, display an improved photocatalytic activity for MB degradation with an apparent rate constant (k) of 0.019 min−1. Additionally, CdS nanostructures sustained a good photostability after five consecutive cycles. The higher photocatalytic activity of CdS nanostructure is attributed to an efficient separation of photogenerated electron‐hole pairs stimulated by its optimal molar ratio, optimal temperature and surface morphology. Our synthesized stable nanostructures have potential for dye contaminated waste‐water treatment.

Thermodynamic properties, electrochemical properties, and interaction behaviors of quaternary ammonium salts-based deep eutectic solvents

To gain a deeper understanding of the formation mechanism for quaternary ammonium salts-based deep eutectic solvents (DESs), it is of great significance to investigate the interaction between hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), as well as their physicochemical properties. In this study, tetrapropylammonium bromide (TPAB) or tetrabutylammonium bromide (TBAB) as HBA and malonic acid (MA) as HBD with a molar ratio of 1:1 or 1:1.5 were to synthesize four DESs of [TPAB]:[MA]-1, [TPAB]:[MA]-1.5, [TBAB]:[MA]-1 and [TBAB]:[MA]-1.5. The thermodynamic properties, electrochemical properties, and interaction behaviors of these DESs were investigated. The thermodynamic parameters of the standard entropy, lattice energy, molar refraction, molar polarization, and molar electrical conductivity for all DESs were calculated in terms of the Glasser’s classical theory, the molar surface Gibbs energy definition, the molar electrical conductivity definition, and Lorentz-Lorenz equation. Through linear scanning curve tests based on the three-electrode method, electrochemical potential windows (EPW) of all DESs were significantly higher than 2 V. Furthermore, according to DFT calculation and COSMO-RS theoretical model, the sequence of interaction strength for quaternary ammonium salts-based DESs was arranged as follows: [TBAB]:[MA]-1 > [TPAB]:[MA]-1 > [TBAB]:[MA]-1.5 > [TPAB]:[MA]-1.5. These fundamental theoretical studies help to provide significant theoretical reference value for the design of DESs with special properties, and promote the application range of DESs.

Recovery of Lithium from Industrial Li-Containing Wastewater Using Fluidized-Bed Homogeneous Granulation Technology

In this study, a novel fluidized-bed homogeneous granulation (FBHo-G) process was developed to recover lithium (Li) from industrial Li-impacted wastewater. Five important operational variables (i.e., temperatures, pH, [P]0/[Li]0 molar ratios, surface loadings, and up-flow velocities (Umf)) were selected to optimize the Li recovery (TR%) and granulation ratio (GR%) efficiencies of the process. The optimal operational conditions were determined as the following: a temperature of 75 °C, pH of 11.5, [P]0/[Li]0 of 0.5, surface loading of 2.5 kg/m2·h, and Umf of 35.7 m/h). The TR% and GR% at optimal condition could be as much as 90%. The material characterization of the recovery pellet products showed that they were highly crystallized Li3PO4 (purity ~88.2%). The pellets had a round shape and smooth surface with an average size of 0.65 mm, so could easily be stored and transported. The high purity enables them to be further directly reused as raw materials for a wide range of industrial applications (e.g., in the synthesis of cathode materials). Our calculation shows that the FBHo-G process could recover up to 0.1845 kg of lithium per cubic meter of Li-containing wastewater, at a recovery rate of ~90%. A brief technoeconomic analysis shows that FBHG process had economic viability, with an estimate production cost of USD 26/kg Li removed, while the potential gained profit for selling lithium phosphate pellets could be up to USD 48 per the same volume of wastewater and the net profit up to USD 22/m3 Li treated. In all, fluidized-bed homogeneous granulation, a seedless one-step recovery process, opens a promising pathway toward a green and sustainable recycling industry for the recovery and application of the resource-limited lithium element from nonconventional water sources.

A Review on the Recent Progress of Layered Double Hydroxides (LDHs)-based Catalysts for Heterocyclic Synthesis

Abstract: Over the past decade, heterocyclic compounds and their derivatives have emerged as promising substances with potential pharmacological applications due to their interesting biological properties. The significance of heterocyclic compounds in drug discovery and development is evident from the fact that a majority of drugs in the pharmaceutical market incorporate heterocyclic compounds as active substances or ingredients. Various synthetic methods and advancements have been devised to prepare these heterocyclic compounds using diverse catalysts under mild conditions. Layered double hydroxides (LDHs)-based materials have gained considerable attention across different fields, and their usability can be significantly enhanced via the selection of metal cations, their molar ratios, surface complexation, and intercalation modifications. The synthesis and application of LDH-based materials as catalysts have garnered increasing interest due to their exceptional properties. Moreover, LDH-based materials have found extensive use as heterogeneous catalysts in the synthesis of numerous heterocyclic compounds. This review presents the latest developments in the catalytic application of LDH-based materials as solid heterogeneous catalysts in the synthesis of heterocyclic compounds, covering literature published from 2018 to 2023.

Characterization of camphor: thymol or dl-menthol eutectic mixtures; Structure, thermophysical properties, and lidocaine solubility

The low solubility of drugs in aqueous media is a major problem for the pharmaceutical industry. Among the solutions proposed, the use of eutectic mixtures can be highlighted. In them, the components used can also increase the therapeutic advantages of the active principle. In this work, we analyzed the solubility of lidocaine in mixtures of camphor + thymol or dl-menthol. These binary eutectic solvents were also characterized. For all this, several NMR techniques were used and different thermophysical properties (density, speed of sound, refraction index, isobaric molar heat capacity, surface tension, and kinematic viscosity) were measured. The results indicated that the interaction of camphor with thymol was stronger than with dl-menthol, providing a more compact fluid. On the contrary, the steric hindrance was greater in the mixture with dl-menthol, giving rise to a more viscous liquid. Furthermore, the lidocaine was significantly more soluble (up to 540 times) in these mixtures than in water. The lidocaine showed the strongest interactions with thymol molecules, somewhat weaker with dl-menthol, and the weakest were with camphor ones.

Effect of Tween and CTAB surfactants on aqueous solubility of the silibinin anticancer drug studied by using physicochemical properties at 310.15 K

The silibinin (SB) is an anticancer drug exhibits partial solubility in aqueous medium due to its slightly hydrophobic nature. In this context, the aqueous solubility of SB with Tween 40 (Tw 40), Tween 60 (Tw 60), Tween 80 (Tw 80) and Cetyltrimethylammonium bromide (CTAB) surfactants at 310.15 K are reported. The physicochemical properties (PCPs) such as density (ρ, g cm−3), Apparent Molar Volume (Vϕ, cm3·mol−1), viscosity (η, mPa.s), surface tension (γ, mNm−1), friccohesity (σ, s.m−1), activation energy (Δµ2*, kJ/mol), and molecular radii (r, nm) of SB with aqueous solution of Tw 40, Tw 60, Tw 80 and CTAB surfactants separately. The PCPs reflects the state of intermolecular forces (IMF) developed between SB and aqueous solutions of Tween (40, 60, 80) and CTAB surfactants with concentration varied from 25 to 150 µM (µM). This study focused on intermolecular interacting mechanism determined by using PCPs to evaluate self-aggregation potential of SB in aqueous surfactants solution. The PCPs data furnished interaction and structure breaking behavior of SB with surfactant molecules. The development of hydrogen bond (HB), hydrophilic, hydrophobic and electrostatic interactions of SB with surfactants which revealed that the structure dependent interacting activities enhances with increasing concentration of SB in aqueous surfactants.

Synergized enzyme-ultrasound-assisted aqueous two-phase extraction and antioxidant activity validation of polysaccharides from tobacco waste

A powerful and innovative technique was developed to efficiently extract and refine polysaccharides from tobacco waste. This was achieved through a combination of enzyme and ultrasound-assisted extraction assisted aqueous two-phase extraction (EUAATPE). The formation of an aqueous two-phase system (ATPS) using various salts and ethanol was investigated. ATPS of 18.0 % (NH4)2SO4 (w/w) and 25.0 % ethanol (w/w) was chosen due to its favorable selection extraction ability and high recovery of 93.68 ± 0.40 %. By utilizing both single-factor experiments and response surface method (RSM), the key factors involved in the EUAATPE process were optimized. The optimal conditions were as follows: ultrasonic power 180 W, ultrasonic time 9 min, cellulase concentration 2.0 %, pectinase concentration 1.0 %, extraction temperature 50 °C, extraction time 1.5 h, and liquid-to-solid ratio 30:1 (g/g). Under the optimal conditions, the extraction yield of polysaccharides was 6.72 ± 0.11 (mg/g), and the purity of the polysaccharides from the bottom phase was 78.73 ± 3.17 %. EUAATPE resulted in a significant enhancement in the extraction yield and purity of polysaccharides from tobacco waste compared to traditional methods such as hot water extraction (HWE), ultrasound-assisted extraction (UAE) and enzyme-assisted extraction (EAE). Polysaccharides of tobacco waste obtained from various methods had analogous monosaccharide compositions, different molar ratio compositions and surface structure characteristics. Moreover, all polysaccharides exhibited a certain extent antioxidant activities and polysaccharides from the bottom phase (PBP) extracted by EUAATPE showed superior antioxidant activity. Hence, EUAATPE, being an innovative and eco-friendly extraction technique, presents a productive substitute for extracting and refining polysaccharides from discarded tobacco resources.

Monodispersed Renewable Particles by Cascade and Density Gradient Size Fractionation to Advance Lignin Nanotechnologies.

Control over particle size and shape heterogeneity is highly relevant to the design of photonic coatings and supracolloidal assemblies. Most developments in the area have relied on mineral and petroleum-derived polymers that achieve well-defined chemical and dimensional characteristics. Unfortunately, it is challenging to attain such control when considering renewable nanoparticles. Herein, a pathway toward selectable biobased particle size and physicochemical profiles is proposed. Specifically, lignin is fractionated, a widely available heterogeneous polymer that can be dissolved in aqueous solution, to obtain a variety of monodispersed particle fractions. A two-stage cascade and density gradient centrifugation that relieves the need for solvent pre-extraction or other pretreatments but achieves particle bins of uniform size (~60 to 860nm and polydispersity, PDI<0.06, dynamic light scattering) along with characteristic surface chemical features is introduced. It is found that the properties and associated colloidal behavior of the particles are suitably classified in distinctive size populations, namely, i) nanoscale (50-100nm), ii) photonic (100-300nm) and iii) near-micron (300-1000nm). The strong correlation that exists between size and physicochemical characteristics (molar mass, surface charge, bonding and functional groups, among others) is introduced as a powerful pathway to identify nanotechnological uses that benefit from the functionality and cost-effectiveness of biogenic particles.

Masticatory habits of the adult Neanderthal individual BD 1 from La Chaise-de-Vouthon (France).

The analysis of dental wear provides a useful approach for dietary and cultural habit reconstructions of past human populations. The analysis of macrowear patterns can also be used to better understand the individual chewing behavior and to investigate the biomechanical responses during different biting scenarios. The aim of this study is to evaluate the diet and chewing performance of the adult Neanderthal Bourgeois-Delaunay 1 (BD 1) and to investigate the relationship between wear and cementum deposition under mechanical demands. The macrowear pattern of BD 1 was analyzed using the occlusal fingerprint analysis method. We propose a new method for the bilateral measurement of the cementum volume along both buccal and lingual sides of the molar root. BD 1's anterior dentition is more affected by wear compared to the posterior one. The macrowear pattern suggest a normal chewing behavior and a mixed-diet coming from temperate environments. The teeth on the left side of the mandible display greater levels of wear, as well as the buccal side of the molar crowns. The cementum analysis shows higher buccal volume along the molar roots. BD1 could have been preferably chewing on the left side of the mandible. The exploitation of various food resources suggested by the macrowear analysis is compatible with the environmental reconstructions. Finally, the greater wear on the buccal side of the molar occlusal surface and the greater volume of cementum in that side of the molar roots offers a preliminary understanding about the potential correlation between dental wear and cementum deposition.

Molecular Interaction Activities of Phenylephrine Hydrochloride with Aqueous System by using Physicochemical Properties at 298.15, 303.15, 308.15 and 313.15 K

Abstract: The solubilizing tendency of the phenylephrine hydrochloride (PHC) with water was supported by the intermolecular interaction (IMI). The effect of PHC concentration with water molecules on the interaction by using physicochemical properties (PCP) was investigated at 298.15, 303.15, 308.15 and 313.15 K. The PCP such as density (ρ, g cm -3 ), Apparent Molar Volume (Vϕ,cm 3 ·mol−1 ), viscosity (η, mPa.s), and surface tension (γ,mNm-1 ) of PHC in aqueous solution have been determined at 298.15, 303.15, 308.15 and 313.15 K. The PCP determine the state of intermolecular forces (IMF) between PHC and water (W). The concentration of PHC ranged from 0.02- 0.10 millimolar (mM) as a binary system in water. This study shows molecular interaction mechanism moderated through PCPs to assess state of IMF produced on PHC-Water interaction at 298.15, 303.15, 308.15 and 313.15 K which revealed that structural potential of PHC with water responsible for develop interaction. The PCP data confirms structural behavior of PHC with water for intermolecular interaction and increases with increasing concentration of PHC. The temperature dependent solubility determined at 298.15, 303.15, 308.15 and 313.15 K which indicates that on increasing temperature the significant change found in PCP. This is due to structure breaking effects of PHC with water furnished disruption of hydrogen bond (HB) in water and electrostatic interactions (EI).

Aβ Amyloid Fibers Drastically Alter the Topography and Mechanical Properties of Lipid Membranes.

Alzheimer's disease (AD) is related to the fibrillation of the Aβ peptides at neuronal membranes, a process that depends on the lipid composition and may impart different physical states to the membrane. In the present work, we study the properties of the Aβ peptide when mixed with a zwitterionic lipid (DMPC), using the Langmuir monolayer technique as an approach to control membrane physical conditions. First, we build on previous characterizations of pure Aβ monolayers and observe that, in addition to high shear, these films present a pronounced compressional hysteresis. When Aβ is assembled with DMPC in a binary film, the resulting membranes become heterogeneous, with a peptide-enriched phase distributed in a network-like pattern, and they exhibit a lateral transition that depends on the Aβ content. At lower peptide proportions, the films segregate into two well-defined phases: one consisting of lipids and another enriched with peptides. The reflectivity of these phases differs from that obtained for pure Aβ films. Thus, the formed fibers effectively cover most of the interface area and remain stable at higher pressures (from 20 to 30 mN m-1 depending on Aβ content) compared to pure peptide films (17 mN m-1). Furthermore, such structures induce a compressional hysteresis in the film, similar to that of pure peptide films (which is nonexistent in the pure lipid monolayer), even at low peptide proportions. We claim that the mechanical properties at the interface are governed by the size of the fibril-like structures. Based on the low molar fractions and surface packing at which these phenomena were observed, we postulate that as a consequence of peptide intermolecular interactions, Aβ may have drastic effects on the molecular arrangement and mechanical properties of a lipid membrane.

Chewing, dentition and tooth wear in Hippopotamidae (Hippopotamus amphibius and Choeropsis liberiensis).

Among mammals, hippopotamids ('hippos') have been described as the species with the lowest chewing efficacy despite elaborate enamel folds on the occlusal surface or their cheek teeth, which was hypothesized to result from the lack of a grinding chewing motion. We investigated the chewing and dentition of the two extant hippo species, the common hippo (Hippopotamus amphibius) and the pygmy hippo (Choeropsis liberiensis), making (video) observations of live animals and gathering data on museum specimens (n = 86 H. amphibius and 26 C. liberiensis skulls). Hippos have a low degree of anisodonty (differences in width between maxillary and mandibular cheek teeth) and anisognathy (difference in width between the upper and the lower jaw), corresponding to a mainly orthal (up-and-down) chewing motion. The two hippo species differ slightly, but distinctively, in their anterior dental morphology and chewing mode. In both species, the canines do not completely prevent a lateral jaw movement but would, in theory, permit this movement until the mandibular canines get into contact with the maxillary protruding snout. This movement is only realized, to a small extent, in pygmy hippos, leaving distinct wear traces on their incisors and creating relatively wider wear facets on the maxillary canines. In common hippos, the interlocking upper and lower incisors prevent lateral jaw movement. Corresponding contact wear facets are evident on the medial aspect of the upper, and on the lateral aspect of the lower incisors-unless museal reconstructions mispositioned these teeth. If these facets are interpreted as an indication for a relic of a lateral jaw movement that was probably more prominent in hippo ancestors, i.e. if we assume that hippos evolved orthal chewing secondarily, several other characteristics of hippos can be explained, such as a low degree of hypsodonty (in the absence of distinct attrition due to a grinding chewing movement), a secondary loss of complexity in their enamel schmelzmuster, a secondary evolution of a wide mouth gape, a reduction in anisodonty compared to their ancestors, and the evolution of a bilaterally symmetrical ('trifoliate') enamel folding pattern on the molar occlusal surface from an ancestral bunoselenodont condition. As an underlying driving force, selection for intraspecific combat with canines and incisors, necessitating a wide gape and a rigid jaw, has been suggested.

Influence of Reduction with NaBH4 and HCl in Obtaining Amino Derivatives of Cashew Gum and Cytotoxic Profile

Tree-exuded gums are natural polymers that represent an abundant raw material in the food and pharmaceutical industries. The cashew gum can be obtained by exudation of trees of the genus Anacardium, a native species of the Brazilian northeast; its polymer consists of monosaccharide units propitious to the action of chemical reactions that tend to improve their intrinsic characteristics among them, as the degree of hydro-solubility. The objective of this work was to modify the exudate gum of Anacardium occidentale (cashew gum (CG)) through an amine reaction. The modification was confirmed by Nuclear Magnetic Resonance (1H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), zeta potential, and thermogravimetric analysis (TG). In addition, the chemical modification altered the molar mass and surface charge of the CG, and the amino group binding to the CG polymers was confirmed by FTIR spectra. In addition, cytotoxicity tests were performed where cell viability was estimated by an MTT assay on RAW 264.7 macrophages. Through these tests, it was found that the amine caused an increase in the thermal stability of the amino compounds and did not present cytotoxic potential at concentrations below 50.0 mg/L.

Influence of diameter in the stress distribution of extra-short dental implants under axial and oblique load

Aim: This study evaluated the influence of a wide diameter on extra-short dental implant stress distribution as a retainer for single implant-supported crowns in the atrophic mandible posterior region under axial and oblique load. Methods: Four 3D digital casts of an atrophic mandible, with a single implant-retained crown with a 3:1 crown-to-implant ratio, were created for finite element analysis. The implant diameter used was either 4 mm (regular) or 6 mm (wide), both with 5 mm length. A 200 N axial or 30º oblique load was applied to the mandibular right first molar occlusal surface. The equivalent von Mises stress was recorded for the abutment and implant, minimum principal stress, and maximum shear stress for cortical and cancellous bone. Results: Oblique load increased the stress in all components when compared to axial load. Wide diameter implants showed a decrease of von Mises stress around 40% in both load directions at the implant, and an increase of at least 3.6% at the abutment. Wide diameter implants exhibited better results for cancellous bone in both angulations. However, in the cortical bone, the minimum principal stress was at least 66% greater for wide than regular diameter implants, and the maximum shear stress was more than 100% greater. Conclusion: Extra-short dental implants with wide diameter result in better biomechanical behavior for the implant, but the implications of a potential risk of overloading the cortical bone and bone loss over time, mainly under oblique load, should be investigated.

Effect of xenon, an apolar general anaesthetic on the properties of the DPPC bilayer

The effect of xenon, a general anaesthetic, on the properties of the fully hydrated dipalmitoylphosphatidylcholine (DPPC) bilayer is investigated by molecular dynamics simulations with two different force fields. Considering the well-known pressure reversal of the anaesthetic effect, we are looking for such changes that are reverted by the increase of the pressure, and hence can be relevant in explaining the molecular mechanism of general anesthesia. The results show that, besides its main preference for staying in the middle of the membrane, xenon also has a secondary preference for positions at the outer boundary of the hydrocarbon region, close to the crowded domain of the polar headgroups. This outer preference is a result of the interplay of the increasing attraction the xenon atoms experience and the decreasing free volume available for them upon going away from the middle of the membrane. It also turns out that any change that might be relevant in explaining the anaesthetic effect is related to xenon atoms staying in this outer preferred position. Since the model we employed does not account for the polarizability of the xenon atoms, and hence misses a part of the thermodynamic driving force of the preference for this outer position, all results should be considered as a lower bound estimate of the real effect. It is found that the xenon atoms induce a lateral swelling of the membrane by pushing the DPPC molecules farther away from each other, which, due to the insensitivity of the membrane thickness to the presence of xenon, naturally results in an increase of also the membrane volume. On the other hand, pressure increases the membrane thickness by increasing the order of the lipid tails, while it also causes a lateral shrinking of the bilayer. The net effect of these two opposite contributions is still a decrease of the membrane volume. In the light of these results, we propose to refine the 70 years old ‘critical volume hypothesis’ to a ‘critical surface area hypothesis’, claiming that general anesthesia occurs if the molar surface area of the membrane exceeds a critical value. Finally, the xenon-induced lateral swelling results in an increase of the empty space in the hydrocarbon region, allowing the DPPC molecules to move more freely, and hence increasing their lateral diffusion coefficient. All these changes are clearly reverted by pressure, and thus may well be relevant in respect of the molecular mechanism of general anesthesia.

Effects of Four Extraction Methods on Structure and In Vitro Fermentation Characteristics of Soluble Dietary Fiber from Rape Bee Pollen.

In this study, soluble dietary fibers (SDFs) were extracted from rape bee pollen using four methods including acid extraction (AC), alkali extraction (AL), cellulase extraction (CL) and complex enzyme extraction (CE). The effects of different extraction methods on the structure of SDFs and in vitro fermentation characteristics were further investigated. The results showed that the four extraction methods significantly affected the monosaccharide composition molar ratio, molecular weight, surface microstructure and phenolic compounds content, but showed little effect on the typical functional groups and crystal structure. In addition, all SDFs decreased the Firmicutes/Bacteroidota ratio, promoted the growth of beneficial bacteria such as Bacteroides, Parabacteroides and Phascolarctobacterium, inhibited the growth of pathogenic bacteria such as Escherichia-Shigella, and increased the total short-chain fatty acids (SCFAs) concentrations by 1.63-2.45 times, suggesting that the bee pollen SDFs had a positive regulation on gut microbiota. Notably, the SDF obtained by CE exhibited the largest molecular weight, a relatively loose structure, higher extraction yield and phenolic compounds content and the highest SCFA concentration. Overall, our results indicated that CE was an appropriate extraction method of high-quality bee pollen SDF.

Assessment of OXIS contacts-a comparison of three methods.

To compare OXIS contacts by means of Replication using Sectional die Models (RSM) and Photographs of the Models (PM) with Direct Clinical Examination (DCE) in a sample of preschool children aged 3-4years. A retrospective cross-sectional study was performed using existing records of sectional die models and their photographs among 4257 contacts of 1104 caries-free pre-school children. Two calibrated examiners scored the contacts between the distal surface of the primary first molar and mesial surface of the primary second molar using OXIS criteria from the occlusal view using the RSM & PM methods. These were compared to the OXIS scores from DCE method which was available from previous records. Kappa agreement was used to compare results obtained RSM and PM methods with DCE. The kappa agreement between the RSM and DCE methods was 98.48%; and between the PM and DCE methods was 99.42%, both of which indicated perfect agreement. The RSM and PM methods were found to have an excellent agreement in scoring OXIS contacts when compared to the DCE method. PM was found to be slightly more accurate than the RSM method for scoring OXIS contacts.