In vitro investigation of electrophoretically deposited bioactive hydroxyapatite/chitosan coatings reinforced by graphene

&#x110,o&#x161,i&#x107,, Marija,Erakovi&#x107,, Sanja,Jankovi&#x107,, Ana,Vuka&#x161,inovi&#x107,-Sekuli&#x107,, Maja,Mati&#x107,, Ivana Z.,Stojanovi&#x107,, Jovica,Rhee, Kyong Yop,Mi&#x161,kovi&#x107 Elsevier 2017 Journal of industrial and engineering chemistry Vol.47 No.-

<P><B>Abstract</B></P> <P>Graphene (Gr) and natural polymer chitosan (CS) were introduced to hydroxyapatite (HAP) to produce a three-component composite coating, which was fabricated by cathodic electrophoretic deposition on Ti substrates in an ethanol suspension. These HAP/CS/Gr coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements and found that the graphene into HAP/CS composites significantly improves their morphology, thermal stability, and bioactivity. Both HAP/CS and HAP/CS/Gr composite coatings are classified as non-cytotoxic when tested against healthy peripheral blood mononuclear cells (PBMC), while antibacterial activity against <I>Staphylococcus aureus</I> and <I>Escherichia coli</I> could not be verified.</P>

A combinatorial constraint satisfaction problem dichotomy classification conjecture

Ne&#x161,et&#x159,il, Jaroslav,Siggers, Mark H.,Zá,dori, Lá,szló Elsevier 2010 European journal of combinatorics : Journal europ& Vol.31 No.1

<P><B>Abstract</B></P><P>We further generalise a construction–the <I>fibre construction</I>–that was developed in an earlier paper of the first two authors. The extension in this paper gives a polynomial-time reduction of CSP(H) for any relational system H to CSP(P) for any relational system P that meets a certain technical partition condition, that of being <SUB>K3</SUB>-<I>partitionable</I>.</P><P>Moreover, we define an equivalent condition on P, that of being <I>block projective</I>, and using this show that our construction proves NP-completeness for exactly those CSPs that are conjectured to be NP-complete by the CSP dichotomy classification conjecture made by Bulatov, Jeavons and Krohkin, and by Larose and Zádori. We thus provide two new combinatorial versions of the CSP dichotomy classification conjecture.</P><P>As with our previous version of the fibre construction, we are able to address restricted versions of the dichotomy conjecture. In particular, we reduce the Feder–Hell–Huang conjecture to the CSP dichotomy classification conjecture, and we prove the Kostochka–Nešetřil–Smolíková conjecture. Although these results were proved independently by Jonsson et al. and Kun respectively, we give different, shorter, proofs.</P>

Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells

Nam, Dong Heon,Zhang, Jenny Z.,Andrei, Virgil,Kornienko, Nikolay,Heidary, Nina,Wagner, Andreas,Nakanishi, Kenichi,Sokol, Katarzyna P.,Slater, Barnaby,Zebger, Ingo,Hofmann, Stephan,Fontecilla&#x2010,Ca John Wiley and Sons Inc. 2018 Angewandte Chemie Vol.57 No.33

<P><B>Abstract</B></P><P>Hydrogenases (H<SUB>2</SUB>ases) are benchmark electrocatalysts for H<SUB>2</SUB> production, both in biology and (photo)catalysis in vitro. We report the tailoring of a p‐type Si photocathode for optimal loading and wiring of H<SUB>2</SUB>ase through the introduction of a hierarchical inverse opal (IO) TiO<SUB>2</SUB> interlayer. This proton‐reducing Si|IO‐TiO<SUB>2</SUB>|H<SUB>2</SUB>ase photocathode is capable of driving overall water splitting in combination with a photoanode. We demonstrate unassisted (bias‐free) water splitting by wiring Si|IO‐TiO<SUB>2</SUB>|H<SUB>2</SUB>ase to a modified BiVO<SUB>4</SUB> photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation. Connecting the Si|IO‐TiO<SUB>2</SUB>|H<SUB>2</SUB>ase to a photosystem II (PSII) photoanode provides proof of concept for an engineered Z‐scheme that replaces the non‐complementary, natural light absorber photosystem I with a complementary abiotic silicon photocathode.</P>

Asymptotics for self-normalized random products of sums of i.i.d. random variables

Pang, T.X.,Lin, Z.Y.,Hwang, K.S. Academic Press 2007 Journal of mathematical analysis and applications Vol.334 No.2

Let {X,X<SUB>i</SUB>;i>=1} be a sequence of independent and identically distributed positive random variables, which is in the domain of attraction of the normal law, and t<SUB>n</SUB> be a positive, integer random variable. Denote S<SUB>n</SUB>=@?<SUB>i=1</SUB><SUP>n</SUP>X<SUB>i</SUB>, V<SUB>n</SUB><SUP>2</SUP>=@?<SUB>i=1</SUB><SUP>n</SUP>(X<SUB>i</SUB>-X@?)<SUP>2</SUP>, where X@? denotes the sample mean. Then we show that the self-normalized random product of the partial sums, (@?<SUB>k=1</SUB><SUP>t<SUB>n</SUB></SUP>S<SUB>k</SUB>kμ)<SUP>&</SUP>mu;<SUP>V''<SUB>t'n</SUB></SUP>, is still asymptotically lognormal under a suitable condition about t<SUB>n</SUB>.

Effect of alendronate on healing of extraction sockets and healing around implants

Kim, J&#x2010,H,Park, Y&#x2010,B,Li, Z,Shim, J&#x2010,S,Moon, H&#x2010,S,Jung, H&#x2010,S,Chung, M&#x2010,K Blackwell Publishing Ltd 2011 Oral diseases Vol.17 No.7

<P><I>Oral Diseases</I> (2011) <B>17</B>, 705–711</P><P><B>Objectives: </B> The purpose of this study was to evaluate the effect of alendronates on healing of extraction sockets and healing around implants in the maxilla of rats.</P><P><B>Materials and Methods: </B> Twenty‐four Sprague–Dawley rats were used. The rats in bisphosphonate group were subcutaneously injected with alendronate (5.0 mg kg<SUP>‐‐1</SUP>) three times a week for 4 weeks. Both sides of the maxillary first molars were extracted, and customized titanium implants (Ø1.5 × 2.0 mm) were placed immediately into one side. Rats were killed at 3, 7, 14, or 28 days following surgery.</P><P><B>Results: </B> New bone formation in extraction sockets, bone area around the implant site, and bone–implant contact were not delayed in the bisphosphonate group. The tartrate‐resistant acid phosphatase positive cell count did not differ between bisphosphonate and control groups; however, empty lacunae were observed significantly more in bisphosphonate group. The differences in empty lacunae were shown at different time points between the implant sites and extraction sites: at 7 days after extraction, and at 14 and 28 days after implantation.</P><P><B>Conclusions: </B> Alendronates seemed to decrease bone resorption but not to decrease bone formation. Empty lacunae were observed significantly more at later time points in implant sites compared to extraction sockets.</P>

Grazing Incidence X - ray Diffraction (GIXRD) Studies of the Structure of Si₁_xGex / Si Surface Alloy

Y. Shi,R. Zhao,C. Z. Jiang,X. J. Fan 한국진공학회(ASCT) 2002 Journal of Korean Vacuum Science & Technology Vol.6 No.2

The Si_(1-x)Ge_x/Si surface alloy (x = 0.3, 0.4 and 0.5), which are prepared by solid source MBE and have the SiGe epilayer thickness of 50Å, are annealed with different parameters. The surface structure analyses of the heterostructure samples are made on a triple-axis X-ray diffractometer in grazing incidence X-ray diffraction (GIXRD) geometry. It has been found that with different annealing time (1.5h, 18h, 64h) and annealing temperature (550℃, 750℃), the SiGe epilayer experienced different strain relaxation process, which was deduced from the GIXRD measurements of the in-plane (220) diffraction peak of Si(001) substrate and the relevant (220) surface diffraction of SiGe epilayer. The results show that the stress relieving and the lateral strain relaxation in the SiGe/Si heterostructure can be promoted by correct annealing, which is very helpful for the preparation of SiGe/Si strained superlattice with fine strain crystallization.

Assessment of Digital PCR as a Primary Reference Measurement Procedure to Support Advances in Precision Medicine

Whale, Alexandra S.,Jones, Gerwyn M.,Pav&#x161,i&#x10d,, Jernej,Dreo, Tanja,Redshaw, Nicholas,Akyü,rek, Sema,Akgö,z, Mü,slü,m,Divieto, Carla,Sassi, Maria Paola,He, Hua-Jun,Cole, Kennet American Association for Clinical Chemistry, Inc. 2018 Clinical chemistry Vol.64 No.9

<P><B>BACKGROUND:</B></P><P>Genetic testing of tumor tissue and circulating cell-free DNA for somatic variants guides patient treatment of many cancers. Such measurements will be fundamental in the future support of precision medicine. However, there are currently no primary reference measurement procedures available for nucleic acid quantification that would support translation of tests for circulating tumor DNA into routine use.</P><P><B>METHODS:</B></P><P>We assessed the accuracy of digital PCR (dPCR) for copy number quantification of a frequently occurring single-nucleotide variant in colorectal cancer (<I>KRAS</I> c.35G>A, p.Gly12Asp, from hereon termed G12D) by evaluating potential sources of uncertainty that influence dPCR measurement.</P><P><B>RESULTS:</B></P><P>Concentration values for samples of <I>KRAS</I> G12D and wild-type plasmid templates varied by <1.2-fold when measured using 5 different assays with varying detection chemistry (hydrolysis, scorpion probes, and intercalating dyes) and <1.3-fold with 4 commercial dPCR platforms. Measurement trueness of a selected dPCR assay and platform was validated by comparison with an orthogonal method (inductively coupled plasma mass spectrometry). The candidate dPCR reference measurement procedure showed linear quantification over a wide range of copies per reaction and high repeatability and interlaboratory reproducibility (CV, 2%–8% and 5%–10%, respectively).</P><P><B>CONCLUSIONS:</B></P><P>This work validates dPCR as an SI-traceable reference measurement procedure based on enumeration and demonstrates how it can be applied for assignment of copy number concentration and fractional abundance values to DNA reference materials in an aqueous solution. High-accuracy measurements using dPCR will support the implementation and traceable standardization of molecular diagnostic procedures needed for advancements in precision medicine.</P>

A Maximum-Likelihood Approach to Force-Field Calibration

Zaborowski, Bartłomiej,Jagieła, Dawid,Czaplewski, Cezary,Hałabis, Anna,Lewandowska, Agnieszka,Z&#x307,mudzin&#x301,ska, Wioletta,Ołdziej, Stanisław,Karczyn&#x301,ska, Agnieszka,Omieczynski, Christian American Chemical Society 2015 JOURNAL OF CHEMICAL INFORMATION AND MODELING Vol.55 No.9

<P>A new approach to the calibration of the force fields is proposed, in which the force-field parameters are obtained by maximum-likelihood fitting of the calculated conformational ensembles to the experimental ensembles of training system(s). The maximum-likelihood function is composed of logarithms of the Boltzmann probabilities of the experimental conformations, calculated with the current energy function. Because the theoretical distribution is given in the form of the simulated conformations only, the contributions from all of the simulated conformations, with Gaussian weights in the distances from a given experimental conformation, are added to give the contribution to the target function from this conformation. In contrast to earlier methods for force-field calibration, the approach does not suffer from the arbitrariness of dividing the decoy set into native-like and non-native structures; however, if such a division is made instead of using Gaussian weights, application of the maximum-likelihood method results in the well-known energy-gap maximization. The computational procedure consists of cycles of decoy generation and maximum-likelihood-function optimization, which are iterated until convergence is reached. The method was tested with Gaussian distributions and then applied to the physics-based coarse-grained UNRES force field for proteins. The NMR structures of the tryptophan cage, a small α-helical protein, determined at three temperatures (<I>T</I> = 280, 305, and 313 K) by Hałabis et al. (J. Phys. Chem. B<x> </x>2012<x>, </x>116<x>, </x>6898−<lpage>6907</lpage>), were used. Multiplexed replica-exchange molecular dynamics was used to generate the decoys. The iterative procedure exhibited steady convergence. Three variants of optimization were tried: optimization of the energy-term weights alone and use of the experimental ensemble of the folded protein only at <I>T</I> = 280 K (run 1); optimization of the energy-term weights and use of experimental ensembles at all three temperatures (run 2); and optimization of the energy-term weights and the coefficients of the torsional and multibody energy terms and use of experimental ensembles at all three temperatures (run 3). The force fields were subsequently tested with a set of 14 α-helical and two α + β proteins. Optimization run 1 resulted in better agreement with the experimental ensemble at <I>T</I> = 280 K compared with optimization run 2 and in comparable performance on the test set but poorer agreement of the calculated folding temperature with the experimental folding temperature. Optimization run 3 resulted in the best fit of the calculated ensembles to the experimental ones for the tryptophan cage but in much poorer performance on the training set, suggesting that use of a small α-helical protein for extensive force-field calibration resulted in overfitting of the data for this protein at the expense of transferability. The optimized force field resulting from run 2 was found to fold 13 of the 14 tested α-helical proteins and one small α + β protein with the correct topologies; the average structures of 10 of them were predicted with accuracies of about 5 Å C<SUP>α</SUP> root-mean-square deviation or better. Test simulations with an additional set of 12 α-helical proteins demonstrated that this force field performed better on α-helical proteins than the previous parametrizations of UNRES. The proposed approach is applicable to any problem of maximum-likelihood parameter estimation when the contributions to the maximum-likelihood function cannot be evaluated at the experimental points and the dimension of the configurational space is too high to construct histograms of the experimental distributions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jcisd8/2015/jcisd8.2015.55.issue-9/acs.jcim.5b00395/production/images/me

Molecular Descriptor Subset Selection in Theoretical Peptide Quantitative Structure–Retention Relationship Model Development Using Nature-Inspired Optimization Algorithms

Z&#x30c,uvela, Petar,Liu, J. Jay,Macur, Katarzyna,Ba&#x328,czek, Tomasz American Chemical Society 2015 ANALYTICAL CHEMISTRY - Vol.87 No.19

<P>In this work, performance of five nature-inspired optimization algorithms, genetic algorithm (GA), particle swarm optimization (PSO), artificial bee colony (ABC), firefly algorithm (FA), and flower pollination algorithm (EPA), was compared in molecular descriptor selection for development of quantitative structure retention relationship (QSRR) models for 83 peptides that originate from eight model proteins. The matrix with 423 descriptors was used as input, and QSRR models based on selected descriptors were built using partial least squares (PLS), whereas root mean square error of prediction (RMSEP) was used as a fitness function for their selection. Three performance criteria, prediction accuracy, computational cost, and the number of selected descriptors, were used to evaluate the developed QSRR models. The results show that all five variable selection methods outperform interval PLS (iPLS), sparse PLS (sPLS), and the full PLS model, whereas GA is superior because of its lowest computational cost and higher accuracy (RMSEP of 5.534%) with a smaller number of variables (nine descriptors). The GA-QSRR model was validated initially through Y-randomization. In addition, it was successfully validated with an external testing set out of 102 peptides originating from Bacillus subtilis proteomes (RMSEP of 22.030%). Its applicability domain was defined, from which it was evident that the developed GA-QSRR exhibited strong robustness. All the sources of the model's error were identified, thus allowing for further application of the developed methodology in proteomics.</P>

Densification, microstructure and hardness of Sm2Zr2O7/SmAlO3 ceramic composites

Z.-G. Liu,R.-X. Zhu,J.H. Ouyang,Y. Zhou 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.4

The densification behaviour of Sm2Zr2O7/SmAlO3 ceramic composites was studied by pressureless sintering at temperatures of 1500-1700 ℃ for 10 h in air. The microstructure and hardness of Sm2Zr2O7/SmAlO3 ceramic composites were investigated by the X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Vickers hardness tester. The Sm2Zr2O7/SmAlO3 ceramic composites are composed of pyrochlore-type Sm2Zr2O7 and perovskite-like SmAlO3 structure. The relative density of Sm2Zr2O7/SmAlO3 ceramic composites increases with increasing sintering temperature. Vickers hardness of Sm2Zr2O7/SmAlO3 ceramic composites slightly increases with increasing SmAlO3 content.