Formation of persisters in <Emphasis Type="Italic">Streptococcus mutans</Emphasis> biofilms induced by antibacterial dental monomer

Antibacterial monomers can combat oral biofilm acids and caries; however, little is known on whether quaternary ammonium monomers (QAMs) would induce drug persistence in oral bacteria. The objectives of this study were to investigate the interactions of Streptococcus mutans (S. mutans) with dimethylaminohexadecyl methacrylate (DMAHDM), and determine for the first time whether DMAHDM could induce persisters in S. mutans. DMAHDM was synthesized using a modified Menschutkin reaction. Dose-dependent killing curves and time-dependent killing curves of planktonic S. mutans and biofilms were determined to evaluate drug persistence, using chlorhexidine (CHX) as control. The inheritability assay, minimum inhibitory concentration (MIC) and live/dead biofilm assay were determined to investigate persister characteristics. DMAHDM matched the killing potency of the gold standard CHX against S. mutans biofilms. DMAHDM and CHX induced drug persistence in S. mutans biofilms but not in planktonic bacteria. S. mutans biofilm persistence was not inheritable in that the tolerance to DMAHDM or CHX of the surviving persisters in the initial population was not transferred to subsequent generations, as displayed by the inheritability assay. The MIC of S. mutans parental strain and induced persisters remained the same. The induced persisters in S. mutans biofilms could be eliminated via higher doses of 300?μg/mL of DMAHDM and CHX. In conclusion, this study showed for the first time that (1) DMAHDM induced persisters only in biofilms, but not in planktonic bacteria; and (2) both DMAHDM-induced and CHX-induced S. mutans persister biofilms could be completely eradicated by even higher concentrations of DMAHDM and CHX. More studies are needed on the induction of persisters in oral biofilms for the development and use of a new generation of antibacterial dental monomers and resins.     

Novel nanohybrid biocatalyst: application in the kinetic resolution of secondary alcohols

In this work, a nanohybrid material was developed and used for the first time to the kinetic resolution of secondary alcohols as rac-indanol, rac-1-phenylethanol (rac-1), rac-1-(3-bromophenyl)-1-ethanol (rac-2) and rac-1-(3-methylphenyl)-1-ethanol (rac-3). Chiral indanol is used as a precursor intermediate for the synthesis of enantiomeric drugs, such as (+)-Indatraline, Irindalone, Indinavir, (+)-Sertraline and Rasagiline mesylate. Chiral 1-phenylethanol is used as an ophthalmic preservative, a solvatochromic dye and an inhibitor of cholesterol absorption and as a mild floral fragrance. For this purpose, the ultrasound irradiation was used to couple APTES on the superparamagnetic nanoparticles surface. Then, the system was activated with glutaraldehyde and used as a support for immobilization of lipase from Pseudomonas fluorescens. Thermal stability analysis was performed in buffer and hexane, showing an excellent stability in buffer solution at 60 °C, holding 72% of the initial activity, even after 7 h. In hexane (40 °C), the immobilized enzyme retained 100% of activity with 693 min of half-life time at 50 °C. The high thermal stability is mainly related to the covalent bonding between enzymes and support. Immobilized lipase on magnetic support proved to be a robust biocatalyst in the kinetic resolution, leading to (S)-indanol with high selectivity (e.e.?>?99%, E?>?200) in 1.75 h at 50 °C, being reused five times without significant loss of the activity and selectivity. The kinetic resolution of rac-1, via acetylation reaction, catalyzed by lipase from Pseudomonas fluorescens immobilized on magnetic support, led to (R)-acetate with enantiomeric excess?>?99% and to the remaining (S)-alcohol with enantiomeric excess of 94%, conversion of 49% and E?>?200, after 48 h of reaction at 40 °C. Under the same reactions conditions, rac-2 and rac-3 were slightly less reactive, since the corresponding (R)-acetates were obtained with conversion values of 44%, but with high enantioselectivity (enantiomeric excesses?>?99% and E values?>?200). These results correspond to an important step in heterogeneous catalysis due to the ability to obtain important precursors for the synthesis of enantiomerically pure chiral drugs and other bioactive substances.     

Polished surface roughness of optoelectronic components made of monocrystalline materials

A study of the mechanism of formation of monocrystal planes of different crystallographic orientations has revealed that in polishing of sapphire the surface roughness parameters Ra, Rq, Rmax decrease in the series c > r > m > a with decreasing dielectric permittivity and thermal conductivity coefficient of the workpiece material, debris particle height, and Lifshitz constant that represents the energy of interaction between the polishing powder grains and the workpiece surface. The minimum allowable values of surface roughness parameters for atomically smooth surfaces have been defined, which linearly depend on interplanar spacings and decrease in the series r > a > c > m.     

Structural Formation and Improved Performances of Chemically Synthesized Composition-Controlled Micron-Sized Fe100−x Co x Particles

Micron-sized composition-controlled Fe_100?x Co _x (20 < x < 75) alloy particles with high purity have been prepared by an optimized reduction reaction. The influence of Co content on the alloying process, structures, and magnetic properties of the products has been studied. The as-synthesized Fe_{100 ?x} Co _x with x < 65 exhibit a single bcc crystal structure. A bcc-FeCo/fcc-Co composite structure can be formed in the Fe_100?x Co _x products with x > 65. Very slight surface oxidation is observed in all the products. The high purity and single bcc-FeCo phase for the well-alloyed Fe_{100 ?x} Co _x particles with x < 65 lead to their high saturation magnetization of 182–220 A m² kg^?1. All the well-alloyed Fe_{100 ?x} Co _x show nearly spherical morphologies with an average particle size of 2–8 μm, which results in their good compactibility with a high compacted density of about 7.4–7.6 g cm^?3. The simple preparation and improved performances for these chemically synthesized composition-controlled FeCo particles show their great potential for applications in near-net-shaped and complex-shaped FeCo-based soft magnetic composite devices.     

Heavy metal removal from simulated wastewater using electrochemical technology: optimization of copper electrodeposition in a membraneless fluidized bed electrode

Heavy metal removal from industrial wastewaters has been intensively studied, since it is well known that they can cause severe problems to human health and aquatic life, even at very low concentrations. In this work, it was demonstrated that electrodeposition in fluidized bed electrode (FBE) can be efficiently employed to remove metal ions from solution, avoid contamination, and recover the metal. Copper electrodeposition from diluted solutions was efficiently performed using a membraneless FBE. The average current efficiency (ACE), average energy consumption (AEC), and space–time yield (AY) was optimized taking into account the operational and process variables. It was noted that for all response variables studied, the raise of supporting electrolyte concentration (C _s) contributed to improvements in the process. The operational conditions current (I) and bed expansion (E) determined the values of CE, Y, and EC under activated control, but the initial copper concentration (C ₀) determined how long the electrodeposition process will work under activated or mass transfer control, thus affecting the average values of CE, Y, and EC. Considering C ₀ of 500 mg L^?1, copper can be optimally recovered with ACE >60 %, AY >38 kg h^?1 m^?3, and AEC <4.0 kWh kg^?1 by applying the lowest I and the highest levels of E and C _s. It was concluded that the electrochemical technology using a membraneless FBE reactor is economically competitive and be applied for the treatment of wastewaters contaminated with copper or other metals.     

A new niobate-based CaO–2CuO–Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> microwave dielectric ceramic composite for LTCC applications

A novel CaO–2CuO–Nb₂O₅ (CCN) ceramic composite was prepared by the solid-state reaction method in the temperature range of 810–890 °C. Typically, the CCN sintered at 870 °C exhibited the excellent microwave properties of ε _r ?=?15.7, Q?×?f?=?28,700 GHz, τ _f = ? 38.4 ppm/°C. The τ _f of CCN was turned to be near zero by adding TiO₂, while the ε _r increased slightly and the Q?×?f decreased. The 0.91CCN–0.09TiO₂ ceramic sintered at 920 °C showed modified properties of ε _r ?=?16.9, Q?×?f?=?21,500 GHz, τ _f = ? 1.6 ppm/°C, which shows potential in LTCC applications.     

Structural relaxation and electrical conductivity of molybdovanadate glass

⁵⁷Fe Mössbauer spectrum of conductive barium iron vanadate glass with a composition of 20BaO·10Fe₂O₃·70V₂O₅ (in mol%) showed paramagnetic doublet peak due to distorted Fe^IIIO₄ tetrahedra with isomer shift (δ) value of 0.37 (±?0.01) mm s^?1. Mössbauer spectra of 20BaO·10Fe₂O₃·xMoO₃·(70???x)V₂O₅ glasses (x?=?20–50) showed paramagnetic doublet peaks due to distorted Fe^IIIO₆ octahedra with δ’s of 0.40–0.41 (±?0.01) mm s^?1. These results evidently show a composition-dependent change of the 3D-skeleton structure from “vanadate glass” phase, composed of distorted VO₄ tetrahedra and VO₅ pyramids, to “molybdate glass” composed of distorted MoO₆ octahedra. After isothermal annealing at 500 °C for 60 min, Mössbauer spectra also showed a marked decrease in the quadrupole splitting (Δ) of Fe^III from 0.70 to 0.77 to 0.58–0.62 (±?0.02) mm s^?1, which proved “structural relaxation” of distorted VO₄ tetrahedra which were randomly connected to FeO₄, VO₅, MoO₆, FeO₆ and MoO₄ units by sharing corner oxygen atoms or edges. DC-conductivity (σ) of barium iron vanadate glass (x?=?0) measured at room temperature was 3.2?×?10^?6 S cm^?1, which increased to 3.4?×?10^?1 S cm^?1 after the annealing at 500 °C for 60 min. The σ’s of as-cast molybdovanadate glasses with x’s of 20–50 were ca. 1.1?×?10^?7 or 1.2?×?10^?7S cm^?1, which increased to 2.1?×?10^?2 (x?=?20), 6.7?×?10^?3 (x?=?35) and 1.9?×?10^?4 S cm^?1 (x?=?50) after the annealing at 500 °C for 60 min. It was concluded that the structural relaxation of distorted VO₄ tetrahedra was directly related to the marked increase in the σ, as generally observed in several vanadate glasses.     

On VLSI interconnect optimization and linear ordering problem

Some well-known VLSI interconnect optimizations problems for timing, power and cross-coupling noise immunity share a property that enables mapping them into a specialized Linear Ordering Problem (LOP). Unlike the general LOP problem which is NP-complete, this paper proves that the specialized one has a closed-form solution. Let f(x,y):?²→? be symmetric, non-negative, defined for x≥0 and y≥0, and let f(x,y) be twice differentiable, satisfying ? ² f(x,y)/?x?y<0. Let π be a permutation of {1,…,n}. The specialized LOP comprises n objects, each associated with a real value parameter r _i , 1≤i≤n, and a cost f(r _i ,r _j ) associated to any two objects if |π(i)?π(j)|=1,1≤i,j≤n, and f(r _i ,r _j )=0 otherwise. We show that the permutation π which minimizes \(\sum_{i= 1}^{n - 1} f( r_{\pi^{ - 1}( i )},r_{\pi^{ - 1}( i + 1 )} )\), called “symmetric hill”, is determined upfront by the relations between the parameter values r _i .     

Sintering behavior,phase structure and electric properties of KNNTS-BKNZ ceramics with excessive alkali metals

We investigated the effect of excessive alkali metals on sintering character, phase structure, dielectric, piezoelectric and ferroelectric properties in KNN-based ceramics thoroughly. The 0.96(K_0.48Na_0.52)_1+xNb_0.93Sb_0.02Ta_0.05O₃–0.04Bi_0.5(K_0.12Na_0.88)_0.5ZrO₃ [(KN) _x NTS-BKNZ] lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. The sintering temperature of (KN) _x NTS-BKNZ ceramics increases gradually while the sintering temperature zone becomes narrow with the increasing x value. For the composition of x?>?0.03, the grains could not grow in all sintering temperature. The coexistence system of rhombohedral and tetragonal phases has been found in (KN) _x NTS-BKNZ ceramics and the T_R?T, T_C, d₃₃, and ε_r show a upward tendency with the increasing x when 0?≤?x?≤?0.03. The maximal piezoelectric coefficient d₃₃ of 415 pC/N was obtained at x?=?0.03. In addition, these ceramics presented good temperature stability. This study exhibits that excessive alkali metals influence sintering character and electrical properties on KNN ceramics deeply. It was believed that this work would be helpful for further understanding the effect of excessive alkali metals on sintering behavior and electric properties in KNN-based ceramics.     

In vitro evaluation of a multispecies oral biofilm over antibacterial coated titanium surfaces

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p?<?0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p?>?0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties.

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Study Ab Initio of the Effect of A-Site Substitution on the Fe1.12Te System

In the present work, our aim is to verify the structural, electronic and magnetic properties of both systems Fe1.12Te and <RTX> (R = Fe, X = Te and T = Ni, Co) in the P4/nmm structure. For this task, we use the density functional theory (DFT) as a theoretical tool integrated into wien2k code (Blaha 2001). The solid Fe1 ? x Mx Te (M = Ni, Co) have been synthesised by Kazakov et al. (Chem. Met. Alloys 3, 155–160 2010). They have observed a systematic shift of the lattice parameters for both systems for M = Ni and Co till x = 0.1, then a secondary phase with the NiAs-type structure appeared when x passes 0.15. Fe1 ? x Nix Te retains its structure in a concentration between x = 0.1 and 0.15, and Fe1 ? x CoxTe retains its structure when x is between 0.05 and 0.1 (Blaha 2001).     

Microwave dielectric properties of Sr<Subscript>0.7</Subscript>Ce<Subscript>0.2</Subscript>TiO<Subscript>3</Subscript>–Sr(Mg<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3</Subscript> ceramics

xSr_0.7Ce_0.2TiO₃–(1???x)Sr(Mg_1/3Nb_2/3)O₃ ceramics, referred to xSCT–(1???x)SMN, were successfully produced by conventional solid-state sintered technology. The compounds, belonging to perovskites with a secondary phase of CeO₂, can be detected even with x down to 0.1 of SCT composition. The overall trend for grain growth illustrates the increase with increasing SCT doping level. The Raman peak at 825 cm^?1 splits into two peaks and causes red shift phenomenon. XPS spectra indicate that Ti and Nb ions exist respectively in tetravalence and pentavalence, and Ce ions exist in trivalence and tetravalence. Dielectrics constant (ε _r ) of SCT–SMN ceramics gradually increases with increasing theoretical dielectric polarizabilities. A wider width of the 825 cm^?1 for FWHM of A_1g mode Raman peaks suggests to a lower Q?×?f value. The increasing tolerance factor in agreement with temperature coefficient of resonant frequency (τ _f ), denotes that the rise of perovskite symmetry. The 0.1SCT–0.9SMN ceramic sintered at 1450?°C for 4 h illustrates excellent microwave dielectric properties with ε _r ?~?35.4, Q?×?f?~?11282 GHz and τ _f ?~?1.7 ppm/°C. Activation energies of 0.1SCT–0.9SMN ceramic at 100, 300 and 500 V, are ~0.436, 0.427 and 0.331 eV, respectively, indicative of a decreased trend with external electric field.     

Barrier properties of crystalline rocks in radionuclide migration

The parameters of the diffusion–sorption interaction of rocks with Sr, Cs, U, Np, Pu, and Am isotopes dissolved in simulated groundwater were determined by in- and through-diffusion methods for monolithic rock samples (gneisses, dolerites, lamprophyres) from the Yeniseisky site of the Nizhnekansy massif. Despite heterogeneous mineral composition and structure of the rocks, these parameters mainly depend on the physicochemical properties of the element and on the open porosity of the rock. The effective diffusion coefficients D _e vary in the order Sr = Cs ? U > Np > Am ≥ Pu, dividing these elements into two groups, the difference between which is 1.5–2 orders of magnitude. With respect to the apparent diffusion coefficient D _a, the elements are also subdivided into two groups, Sr = Cs > Np ≥ U ? Am > Pu, differing by 5 orders of magnitude because of different sorbability of the elements: Pu > Am ? Cs = Sr > U > Np. The end members of this series differ in the sorption capacity coefficient of the rocks, α = D _e/D _a, by 4.5 orders of magnitude.     

Visible-light-induced hydrogen evolution reaction with WS<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>

WS₂ is a promising catalyst for the hydrogen evolution reaction. We have explored photocatalytic properties of ternary sulphoselenides of tungsten (WS _x Se _2?x ) by the dye-sensitized hydrogen evolution. WS _x Se _2?x solid solutions are found to exhibit high activity reaching 2339 μmol h^?1 g^?1 for WSSe, which is three times higher than that of WS₂ alone (866 μmol h^?1 g^?1 ). The turnover frequency is also high (0.7 h^?1 ). Such synergistic effect of selenium substitution in WS₂ is noteworthy.     

Influence of Oxygen on the Tribomechanical Properties of Single Crystals of YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−<Emphasis Type="Italic">δ</Emphasis></Subscript>

This paper reports a study on the mechanical and tribological properties of ab- and a (b) c?planes of YBa₂Cu₃O_7?δ single crystals. The single crystals were grown using a CuO-BaO self-flux method. The oxygenation effect on the mechanical and tribological properties of ab- and a (b) c?planes is reported. For the ab- plane, the hardness and elastic modulus were around 6 and 50 GPa, respectively. In this case, significant differences were not observed among the hardness and elastic modulus at different oxygenation states. However, the hardness and elastic modulus for as-grown and oxygenated YBa₂Cu₃O_7?δ single crystals were different from that of the a (b) c?plane, and were observed to be slightly higher for the as-grown than for the oxygenated samples. For as-grown and oxygenated samples, we observed hardness values around 4.7 and 2.0 GPa, respectively. Regarding the elastic modulus, the values were 75 and 40 GPa, respectively. The indentation fracture toughness values on the ab- plane for the as-grown and oxygenated YBa₂Cu₃O_7?δ single crystal were 3.7 ± 1.2 and 2.9 ± 1.2 MPa m^1/2, respectively. For the ab- plane, the scratch resistance of the as-grown sample was higher than that of the oxygenated sample and the scratches under load were deeper for the oxygenated sample. As regards the a (b) c?plane, the scar features were seemingly constant through all the scratch lengths and the scratches under load were deeper and larger for the oxygenated than that for the as-grown sample.     

Inducement of Itinerant Electron Transport in Charge-Ordered Pr<Subscript>0.6</Subscript>Ca<Subscript>0.4</Subscript>MnO<Subscript>3</Subscript> by Ba Doping

The effects of Ba ²⁺ doping on the electrical and magnetic properties of charge-ordered Pr_0.6Ca_0.4MnO₃ were investigated through electrical resistivity and AC susceptibility measurements. X-ray diffraction data analysis showed an increase in unit cell volume with increasing Ba ²⁺ content indicating the possibility of substituting Ba ²⁺ for the Ca-site. Electrical resistivity measurements showed insulating behavior and a resistivity anomaly at around 220 K. This anomaly is attributed to the existence of charge ordering transition temperature, \(T^{\mathrm {R}}_{\text {CO}}\) for the x = 0 sample. The Ba-substituted samples exhibited metallic to insulator transition (MI) behavior, with transition temperature, T _MI, increasing from ～98 K (x = 0.1) to ～122 K (x = 0.3). AC susceptibility measurements showed ferromagnetic to paramagnetic (FM-PM) transition for Ba-substituted samples with FM-PM transition temperature, T _c, increasing from ～121 K (x = 0.1) to ～170 K (x = 0.3), while for x = 0, an antiferromagnetic to paramagnetic transition behavior with transition temperature, T _N, ～170 K was observed. In addition, inverse susceptibility versus T plot showed a deviation from the Curie–Weiss behavior above T _c, indicating the existence of the Griffiths phase with deviation temperature, T _G, increasing from 160 K (x = 0.1) to 206 K (x = 0.3). Magnetoresistance, MR, behavior indicates intrinsic MR mechanism for x = 0.1 which changed to extrinsic MR for x > 0.2 as a result of Ba substitution. The weakening of charge ordering and inducement of ferromagnetic metallic (FMM) state as well as increase in both T _c and T _MI are suggested to be related to the increase of tolerance factor, τ, and increase of e _g ?electron bandwidth as average ionic radius at A-site, <r _A> increased with Ba substitution. The substitution may have reduced MnO₆ octahedral distortion and changed the Mn–O–Mn angle which, in turn, promotes itinerancy of charge carrier and enhanced double exchange mechanism. On the other hand, increase in A-site disorder, which is indicated by the increase in σ ² is suggested to be responsible for the widening of the difference between T _c and T _MI.     

Effect of CdTe Addition on the Electrical Properties and AC Susceptibility of YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−<Emphasis Type="Italic">δ</Emphasis></Subscript> Superconductor

The effect of CdTe addition on YBa₂Cu₃O_7?δ (CdTe) _x (x = 0–0.10) has been studied. XRD patterns showed the presence of impurities including CdTe for x ≥ 0.05 wt%. The resistance versus temperature curves showed metallic behavior for all samples. The onset temperature T _{c onset} for all samples is between 90 and 92 K. The superconducting transition width, ΔT _c = 4 K for all samples except for x = 0.1 wt% where ΔT _c = 6 K. The superconducting transition determined by AC susceptibility measurement also showed little change in \(T_{\mathrm {c}\chi ^{\prime }}\) (between 89 and 92 K). However, the peak temperature T _p of the imaginary part of the susceptibility χ″, showed a drastic decrease for samples with x > 0.05 wt%. This indicated that the superconducting grains were strongly decoupled for x > 0.05 wt% due to the impurities as observed in the XRD pattern. The intergrain critical current density, J _c at T _p for the x = 0 sample is J _c (82 K) = 17 A cm^?2. These results can be useful in the fabrication of semiconductor/YBCO superconductor hybrid systems.     

Synthesis,Structure, and Superconductivity of (La1.5Pb0.5−<Emphasis Type="Italic">x</Emphasis>Sr<Emphasis Type="Italic">x</Emphasis>)CuO<Emphasis Type="Italic">z</Emphasis>

The substitution of strontium for lead in the material (La_1.5Pb_0.5?xSr _x )CuO _z , x = 0–0.15 has been carried out. A stable and reproducible single phased superconducting materials can be obtained inside an evacuated quartz tube. The X-ray diffraction pattern shows that the superconducting phase can be indexed on the basis of an orthorhombic symmetry (F_mmm) for x = 0 and on the basis of tetragonal symmetry (I_4/mmm) for x > 0. The transition temperature T _c increases as the strontium substitution parameter x increases. We observed the maximal T _c around x = 0.15 with 38 K with fairly large Meissner volume fraction of 38% (FC).     

Comparative study on the role of gelatin,chitosan and their combination as tissue engineered scaffolds on healing and regeneration of critical sized bone defects: an in vivo study

Gelatin and chitosan are natural polymers that have extensively been used in tissue engineering applications. The present study aimed to evaluate the effectiveness of chitosan and gelatin or combination of the two biopolymers (chitosan–gelatin) as bone scaffold on bone regeneration process in an experimentally induced critical sized radial bone defect model in rats. Fifty radial bone defects were bilaterally created in 25 Wistar rats. The defects were randomly filled with chitosan, gelatin and chitosan–gelatin and autograft or left empty without any treatment (n?=?10 in each group). The animals were examined by radiology and clinical evaluation before euthanasia. After 8?weeks, the rats were euthanized and their harvested healing bone samples were evaluated by radiology, CT-scan, biomechanical testing, gross pathology, histopathology, histomorphometry and scanning electron microscopy. Gelatin was biocompatible and biodegradable in vivo and showed superior biodegradation and biocompatibility when compared with chitosan and chitosan–gelatin scaffolds. Implantation of both the gelatin and chitosan–gelatin scaffolds in bone defects significantly increased new bone formation and mechanical properties compared with the untreated defects (P?<?0.05). Combination of the gelatin and chitosan considerably increased structural and functional properties of the healing bones when compared to chitosan scaffold (P?<?0.05). However, no significant differences were observed between the gelatin and gelatin–chitosan groups in these regards (P?>?0.05). In conclusion, application of the gelatin alone or its combination with chitosan had beneficial effects on bone regeneration and could be considered as good options for bone tissue engineering strategies. However, chitosan alone was not able to promote considerable new bone formation in the experimentally induced critical-size radial bone defects.     

Quantification of the Interaction Field in Arrays of Magnetic Nanowires from the Remanence Curves

A method is presented that allows quantifying the average value of the interaction field in arrays of magnetic nanowires from the field difference between the isothermal remanence (IRM) and the DC demagnetizing (DCD) remanence curves when the normalized magnetization is equal to one third. Arrays of magnetic nanowires of different diameters and packing fractions are used to experimentally test the method. The results have been compared with those obtained using the method based on the difference between the remanence coercivity fields and with a mean-field expression for the interaction field, providing a very good agreement and thus validating the method. Additionally, it is shown that both the position (m₀) and the shift along the magnetization axis of the intersection between the remanence curves with respect to the value of one third (δm = m₀ ??1/3) provide qualitative information about the interaction field. The former indicates the type of interaction depending if the intersection is above (m₀ >?1/3) or below (m₀ <?1/3), which corresponds to a ferro or anti-ferro magnetic interaction, respectively. While for the latter, it is shown that the maximum deviation of the Delta-M plot from zero (ΔM_max) corresponds to three times the shift (ΔM_max =?3δm).