Effect of bioactive dental adhesive on periodontal and endodontic pathogens

The objectives of this study were to: (1) develop a new bioactive dental bonding agent with nanoparticles of amorphous calcium phosphate and dimethylaminohexadecyl methacrylate for tooth root caries restorations and endodontic applications, and (2) investigate biofilm inhibition by the bioactive bonding agent against eight species of periodontal and endodontic pathogens for the first time. Bonding agent was formulated with 5?% of dimethylaminohexadecyl methacrylate. Nanoparticles of amorphous calcium phosphate at 30?wt% was mixed into adhesive. Eight species of biofilms were grown on resins: Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Parvimonas micra, Enterococcus faecalis, Enterococcus faecium. Colony-forming units, live/dead assay, biomass, metabolic activity and polysaccharide of biofilms were determined. The results showed that adding dimethylaminohexadecyl methacrylate and nanoparticles of amorphous calcium phosphate into bonding agent did not decrease dentin bond strength (P?>?0.1). Adding dimethylaminohexadecyl methacrylate reduced the colony-forming units of all eight species of biofilms by nearly three orders of magnitude. The killing efficacy of dimethylaminohexadecyl methacrylate resin was: P. gingivalis?>?A. actinomycetemcomitans?>?P. intermedia?>?P. nigrescens?>?F. nucleatum?>?P. micra?>?E. faecalis?>?E. faecium. Dimethylaminohexadecyl methacrylate resin had much less biomass, metabolic activity and polysaccharide of biofilms than those without dimethylaminohexadecyl methacrylate (P?<?0.05). In conclusion, a novel dental adhesive was developed for root caries and endodontic applications, showing potent inhibition of biofilms of eight species of periodontal and endodontic pathogens, and reducing colony-forming units by three orders of magnitude. The bioactive adhesive is promising for tooth root restorations to provide subgingival margins with anti-periodontal pathogen capabilities, and for endodontic sealer applications to combat endodontic biofilms.     

Synthesis and Superconductivity of Layered Compounds with Orthogonal [Zr<Subscript>2</Subscript>N<Subscript>2</Subscript>] Network

Layered α-form ZrNX (X: Cl and Br) compounds with high quality were prepared by chemical vapor transport. The intercalation of alkali metal A (A: Li, Na, K, Rb) was carried out to realize electron doping into the orthogonal [Zr₂N₂] layers. The Rietveld refinement analysis reveals that the [Zr₂N₂] crystalline layers in the intercalation compounds shift mutually in the ab plane when compared with the hosts. Magnetic measurements show that the intercalation compounds A _x ZrNX are changed into superconductors with transition temperature T _c of up to 12 K. Upon the cointercalation of solvent molecules such as THF, T _c decreases to as low as 6.1 K with increasing the interlayer spacing d up to 14 Å, which is similar to the d dependence of T _c recently found in electron-doped α-form TiNX series. We also succeeded in synthesizing another new polymorph of α-Zr₂N₂S by the topochemical reaction between α-form ZrNX and Na₂S. α-Zr₂N₂S (space group: Immm, a = 4.1375(1) Å, b = 3.5422(1) Å, and c = 11.5204(3) Å) has the same α-[Zr₂N₂] layers, whereas the interlayer spacing between two adjacent [Zr₂N₂] layers is effectively decreased by 1/3 when compared with the parent compounds of ZrNX.     

Phenomenological Model of Magnetocaloric Effect in La<Subscript>0.7</Subscript>Ca<Subscript>0.2</Subscript>Ba<Subscript>0.1</Subscript>MnO<Subscript>3</Subscript> Manganite Around Room Temperature

In this work, we studied in detail the magnetic and magnetocaloric properties of the La_0.7Ca_0.2Ba_0.1MnO₃ compound according to the phenomenological model. Based on this model, the magnetocaloric parameters such as the maximum of the magnetic entropy change ΔS _M and the relative cooling power (RCP) have been determined from the magnetization data as a function of temperature at several magnetic fields. The theoretical predictions are found to closely agree with the experimental measurements, which make our sample a suitable candidate for refrigeration near room temperature. In addition, field dependences of \({{\Delta } S}_{\mathrm {M}}^{\max }\) and RCP can be expressed by the power laws \({\Delta S}_{\mathrm {M}}^{\max }\approx a\)(μ ₀ H) ⁿ and RCP ≈b(μ ₀ H) ^m , where a and b are coefficients and n and m are the field exponents, respectively. Moreover, phenomenological universal curves of entropy change confirm the second-order phase transition.     

Electronic and Ferromagnetic Properties of 3<Emphasis Type="Italic">d</Emphasis>(V)-Doped (BaS) Barium Sulfide

The objective of this study is to investigate the electronic structure and ferromagnetic properties of barium sulfide (BaS) doped with vanadium (V) impurity. The calculations were performed by using the first-principle calculations of density functional theory. The lattice constant of Ba_1?x V _x S decreases with increasing concentration (x) of the V atom. We have found that the Ba_0.75 V _0.25S and Ba_0.5 V _0.5S compounds are half-metallic ferromagnets with total magnetic moments of 3 μ _B per V atom, while for high concentration x = 0.75, the Ba_0.25 V _0.75S becomes nearly half metallic due to broadening of 3d (V) states in the gap. The exchange coupling between the 3d (V) levels and conduction bands is ferromagnetic, confirming the magnetic nature of Ba_1?x V _x S compounds.     

A new rabbit model of implant-related biofilm infection: development and evaluation

This study is to establish a rabbit model for human prosthetic joint infection and biofilm formation. Thirty-two healthy adult rabbits were randomly divided into four groups and implanted with stainless steel screws and ultra-high molecular weight polyethylene (UHMWPE) washers in the non-articular surface of the femoral lateral condyle of the right hind knees. The rabbit knee joints were inoculated with 1 mL saline containing 0, 10², 10³, 10⁴ CFU of Staphylococcus epidermidis (S. epidermidis) isolated from the patient with total knee arthroplasty (TKA) infection, respectively. On the 14th postoperative day, the UHMWPE washers from the optimal 10³ CFU group were further examined. The SEM examination showed a typical biofilm construction that circular S. epidermidis were embedded in a mucous-like matrix. In addition, the LCSM examination showed that the biofilm consisted of the polysaccharide stained bright green fluorescence and S. epidermidis radiating red fluorescence. Thus, we successfully create a rabbit model for prosthetic joint infection and biofilm formation, which should be valuable for biofilm studies.     

The H-T and P-T Phase Diagram of the Superconducting Phase in Pd:Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript>

We study the magnetic field vs. temperature (H – T) and pressure vs. temperature (P – T) phase diagrams of the T _c ≈ 5.5 K superconducting phase in Pd _x Bi₂Te₃ (x ≈ 1) using electrical resistivity versus temperature measurements at various applied magnetic fields (H) and magnetic susceptibility versus temperature measurements at various applied magnetic fields (H) and pressure (P). The H – T phase diagram has an initial upward curvature as observed in some unconventional superconductors. The critical field extrapolated to T = 0 K is H _c (0) ≈ 6–10 kOe. The T _c is suppressed approximately linearly with pressure at a rate d T _c /d P ≈ ?0.28 K/GPa.     

Critical Behavior of La<Subscript>0.67</Subscript>Ba<Subscript>0.33</Subscript>Mn<Subscript>0.95</Subscript>Fe<Subscript>0.05</Subscript>O<Subscript>3</Subscript> Manganite

The critical behavior of perovskite manganite La_0.67Ba_0.33Mn_0.95Fe_0.05O₃ at the ferromagnetic–paramagnetic has been analyzed. The results show that the sample exhibited the second-order magnetic phase transition. The estimated critical exponents derived from the magnetic data using various such as modified d’Arrott plot Kouvel–Fisher method and critical magnetization M(T _C, H). The critical exponents values for the La_0.67Ba_0.33Mn_0.95Fe_0.05O₃ are close to those expected from the mean field model β = 0.504 ± 0.01 with T _C = 275661 ± 0.447 (from the temperature dependence of the spontaneous magnetization below T _C ), γ = 1.013 ± 0.017 with T _C = 276132 ± 0.452 (from the temperature dependence of the inverse initial susceptibility above T _C ), and δ = 3.0403 ± 0.0003. Moreover, the critical exponents also obey the single scaling equation of M(H, ε) = |ε| ^β f _±(H/|ε| ^β+γ ).     

A comparative study of lignocellulosic ethanol productivities by <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis> and <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The yeast Saccharomyces cerevisiae is commonly employed in industrial ethanol production, regardless of the capability of Kluyveromyces marxianus strains to produce ethanol at similar or higher levels and on inhibitory conditions. Therefore, in this work strains of S. cerevisiae (ethanol RED and AR5) and K. marxianus (SLP1 and OFF1) were compared for ethanol production from sugarcane bagasse (SCB) and wheat straw (WS) hydrolysates. As it is known, during the lignocellulosic hydrolysis not only free sugars were obtained (SCB, g L^?1: glucose 7.64, xylose 8.38, arabinose 2.43; and WS, g L^?1: glucose 6.07, xylose 6.36, arabinose 2.09) but also growth inhibitors of yeast such as hydroxymethylfurfural and furfural that could modify the fermentation capability. The volumetric ethanol productivity (Q _p) was evaluated, and it was observed that the K. marxianus SLP1 was the most efficient for ethanol production reaching a Q _p of 0.292 and 0.250 g L^?1 h^?1 on SCB and WS hydrolysates, respectively. In contrast, S. cerevisiae AR5 and ethanol RED exhibited a reduced Q _p on SCB, but similar values of Q _p to K. marxianus OFF1 on WS. The results obtained show that it is possible to select K. marxianus yeast strains for ethanol production using SCB and WS hydrolysates obtaining higher Q _p than S. cerevisiae yeast strains. Considering the efficiency of ethanol production and the tolerance to inhibitors, K. marxianus strain SLP1 possesses a great potential as an industrial yeast for lignocellulosic ethanol production.     

Investigation of Magnetic,Magnetocaloric, and Critical Properties of La<Subscript>0.5</Subscript>Ba<Subscript>0.5</Subscript>MnO<Subscript>3</Subscript> Manganite

We present an extensive study of the magnetic properties of a novel La_0.5Ba_0.5MnO₃ perovskite material prepared by the hydrothermal method. The explored sample was structurally studied by the x-ray diffraction (XRD) method which confirms the formation of a pure cubic phase of a perovskite structure with Pm3m space group. The magnetic properties were probed by employing temperature M (T) and external magnetic field M (μ_oH) dependence of magnetization measurements. A magnetic phase transition from ferromagnetic to paramagnetic phase occurs at 339 K in this sample. The maximum magnetic entropy change (\(\left | {{\Delta } S}_{M}^{\max } \right |\)) took a value of 1.4 J kg^??1 K^??1 at the applied magnetic field of 4.0 T for the explored sample and has also been found to occur at Curie temperature (T_C). This large entropy change might be instigated from the abrupt reduction of magnetization at T_C. The magnetocaloric effect (MCE) is maximum at T_C as represented by M (μ_oH) isotherms. The relative cooling power (RCP) is 243.2 J kg^??1 at μ_oH =?4.0 T. Moreover, the critical properties near T_C have been probed from magnetic data. The critical exponents δ, β, and γ with values 3.82, 0.42, and 1.2 are close to the values predicted by the 3D Ising model. Additionally, the authenticity of the critical exponents has been confirmed by the scaling equation of state and all data fall on two separate branches, one for T < T_C and the other for T > T_C, signifying that the critical exponents obtained in this work are accurate.     

Synthesis and high-temperature heat capacity of Gd<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript>

Gd₂Sn₂O₇ gadolinium stannate with the pyrochlore structure has been prepared by solid-state reaction and its high-temperature heat capacity has been determined by differential scanning calorimetry in the temperature range 350–1020 K. The C_p(T) data are shown to be well represented by the classic Maier–Kelley equation. The experimental C_p(T) data have been used to evaluate the thermodynamic functions of gadolinium stannate: enthalpy increment H°(T)–H°(339 K), entropy change S°(T)–S°(339 K), and reduced Gibbs energy Ф°(Т).     

Effect of Nuclear Field on Magnetotransport Quantum Oscillations in InSb<Superscript>1</Superscript>

In combining magneto-transport investigations with NMR (nuclear magnetic resonance) we measured the effect of the nuclear hyperfine field B _H F on quantum oscillations in the transverse magneto-resistivity ρ _xx and in the Hall resistivity ρ _xy of metallically doped n-InSb. Quantitative analysis of the B _H F-induced change in ρ _xx demonstrates that this experiment allows to separate spin splitting phenomena in magneto-transport from effects due to the external magnetic field B. This is used to show that an oscillatory structure in R _H =ρ _xy /B is directly related to a redistribution in the occupation of the two spin states in the lowest Landau level.     

Compounds WAl<Subscript>4</Subscript>, WAl<Subscript>3</Subscript>, W<Subscript>3</Subscript>Al<Subscript>7</Subscript>, and WAl<Subscript>2</Subscript> and Al-W-N combustion products

X-ray diffraction data are presented for combustion products in the Al-W-N system. New, nonequilibrium intermetallic compounds have been identified, their diffraction patterns have been indexed, and their unit-cell parameters have been determined. The phases α-and β-WAl₄ are shown to exist in three isomorphous forms, differing in unit-cell centering. The phases α′-, α″-, and α?-WAl₄ are monoclinic, with a ₀ = 5.272 Å, b ₀ = 17.770 Å, c ₀ = 5.218 Å, β = 100.10°; point groups C12/c1, A12/n1, I12/a1, respectively. The phases β′-, β″-, and β?-WAl₄ are monoclinic, with a ₀ = 5.465 Å, b ₀ = 12.814 Å, c ₀ = 5.428 Å, β = 105.92°; point groups A112/m, B112/m, I112/m, respectively. The compounds WAl₂ and W₃Al₇, identified each in two isomorphous forms, differ in cell metrics (doubling) but possess the same point group: P222. WAl ₂ ^′ : orthorhombic, a ₀ = 5.793 Å, b ₀ = 3.740 Å, c ₀ = 6.852 Å. WAl ₂ ^″ : orthorhombic, a ₀ = 11.586 Å, b ₀ = 3.740 Å, c ₀ = 6.852 Å. W₃Al ₇ ^′ : orthorhombic, Pmm2, a ₀ = 6.225 Å, b ₀ = 4.806 Å, c ₀ = 4.437 Å. W₃Al ₇ ^″ : orthorhombic, Pmm2, a ₀ = 12.500 Å, b ₀ = 4.806 Å, c ₀ = 8.874 Å. The new phase WAl₃: triclinic, P1, a ₀ = 8.642 Å, b ₀ = 10.872 Å, c ₀ = 5.478 Å, α = 104.02°, β = 64.90°, γ = 107.15°.     

High-temperature heat capacity and thermodynamic properties of Tb<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript>

Tb₂Sn₂O₇ has been prepared by solid-state reaction in air at 1473 K over a period of 200 h and its isobaric heat capacity has been studied experimentally in the range 350–1073 K. The C _p(T) data for this compound have no extrema and are well represented by the classic Maier–Kelley equation. The experimental C _p(T) data have been used to evaluate the thermodynamic properties of terbium stannate (pyrochlore structure): enthalpy increment H°(T)–H°(350 K), entropy change S°(T)–S°(350 K), and reduced Gibbs energy Ф°(Т).     

Magnetic Entropy Change by Mean-Field Theory for the Second-Order Phase Transition Manganite Nd<Subscript>0.6</Subscript>Sr<Subscript>0.3</Subscript>Ca<Subscript>0.1</Subscript>Mn<Subscript>0.975</Subscript>Fe<Subscript>0.025</Subscript>O<Subscript>3</Subscript>

In this work, we are going to show the method based on mean-field scaling for the Nd_0.6Sr_0.3Ca_0.1Mn_0.975Fe_0.025 O₃ sample, where from scaling of experimental magnetization data, the mean-field exchange parameter λ and the f function of the equation of state \(M(T,H)=B_{S} [\frac {\left ({H+H_{\text {ex}}} \right )}{T}]\) are directly determined. The scaling approach allows finding the dependence of H _ex on T or higher powers of M, which determine the order of the phase transition. Quantum spin number has been determined. In this study, we use \(\left | {\Delta S_{M} (T)} \right |\) obtained from isothermal magnetization measurements; we compare this result to mean-field theory fittings from a novel scaling method through the use of theoretical results S, g, and λ. The obtained results by mean-field theory are suitable and in good agreement with the classical Maxwell relation.     

Specific Heat Jump at T<Emphasis Type="Italic">c</Emphasis> of High T<Emphasis Type="Italic">c</Emphasis> Superconductors: Effect of Van Hove Singularity

In the BCS framework, exact expressions for the ratio between the jump in the specific heat at T _c and the normal phase specific heat are derived within the Van Hove singularity scenario. Analytical results are obtained for an isotropic s-wave and anisotropic d-wave pairing symmetries. Graphical solutions of the ratio as functions of ω _D /T _c and E _F /T _c , where ω _D is the cutoff energy and E _F is the Fermi energy, show significant deviations from the BCS value of 1.43.     

Electron-Phonon Interaction in the Presence of Strong Coulomb Repulsion

We consider the Hubbard-Holstein model on a 2D tilted eight-site square lattice at quarter fillings having on-site (λ ₁) and inter-site (λ ₂) electron-phonon (EP) interactions and inter-site Coulomb repulsion (V ). Mobility of electrons decreases, and hence, localization of electrons is favored by λ ₁ as well as inter-site Coulomb repulsion in the non-interacting limit (U/t = 0.0). In the interacting case (U/t = 8.0), an initial delocalization effect observed due to the competition between on-site Coulomb repulsion and EP interaction λ ₁ though V favors localization. For smaller λ ₁, the competition between λ ₂ and V increases the delocalization effect. As λ ₂ increases further, localization occurs. In the interacting case, localization occurs at much higher values of λ ₂ due to the additional delocalization effect of U. On-site (S0) and/or large bipolarons are formed with λ ₁ in the presence of V, and inter-site Coulomb repulsion effectively increases λ ₁. Thus, V favors the formation of S0 bipolarons. However, the formation of S1 bipolarons is suppressed by inter-site Coulomb repulsion. An existence of critical λ ₂ = λ _2c is observed for the formation of on-site (S0) and neighboring-site (S1) bipolarons.     

The calorimetry and thermodynamic functions of Nd Mg<Stack><Subscript>3</Subscript><Superscript>I</Superscript></Stack>Mn<Subscript>4</Subscript>O<Subscript>12</Subscript> (Me<Superscript>I</Superscript>-Li,Na, K) manganites in the range from 298.15 to 673 K

The ceramic technology is employed for synthesizing manganites of composition Nd Mg ₃ ^I Mg₃Mn₄O₁₂(Me^I-Li, Na, K). The X-ray technique is used to find that the compounds crystallize in tetragonal syngony. The parameters of their crystal lattices are determined. Their heat capacities are experimentally determined in the range from 298.15 to 673 K, which enables one to reveal second-order phase transitions. In view of these transitions, equations describing the C _p ^° ～ f(T) dependence are derived, and the thermodynamic functions C _p ^° (T), H°(T)-H°(298.15), S°(T), and Φ ^xx (T) are calculated.     

Effects of Iron Contents on the Vortex State in Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>0.5</Subscript>Te<Subscript>0.5</Subscript>

We investigate the effects of iron content on the upper critical field (H _c2) and the activation energy U(T) in thermally activated flux flow in Fe _x Se_0.5Te_0.5 near the superconducting transition temperature T _c . The variations in H _c2(T) with temperature are analyzed using Ginzburg-Landau (GL), Werthamer-Helfand-Hohenberg (WHH) models along with the empirical relation (ER). The obtained values of H _c2(0) depend strongly on the model and the criteria used to determine the transition temperature. However, the general trend is that that H _c2(0) increases with the increasing Fe content. The activation energy U(T) is maximum for x =? 1 and rapidly suppressed by excess or deficiency of iron. The low values of U(T) (～10 meV) reflect the low vortex-pinning nature (due to defects, vacancies, etc.) in the Fe _x Se_0.5Te_0.5 superconductor.     

Crystal structures of Ln<Subscript>2</Subscript>TiO<Subscript>5</Subscript> (Ln = Gd,Dy) polymorphs

Single crystals of four Ln₂TiO₅ polymorphs have been grown, and their structures have been determined: orthorhombic (Gd₂TiO₅, a = 10.460(5), b = 11.317(6), c = 3.750(3) Å, Pnam, Z = 4), hexagonal (Gd_1.8Lu_0.2TiO₅, a = 3.663(3), c = 11.98(1) Å, P6₃/mmc, Z = 1.2), cubic (Dy₂TiO₅, a = 10.28(1) Å, Fd3m, Z = 10.4), and monoclinic (Dy₂TiO₅, a = 10.33(1), b = 3.653(5), c = 7.306(6) Å, β = 90.00(7)°, B2/m, Z = 2.4). The last polymorph has been identified for the first time.