Determination of Microhardness of Remineralized Bleached Surface Subjected to Erosion-An In Vitro Study.

Objectives: The aim of this study is to evaluate the microhardness of remineralized bleached surface subjected to erosion. Materials and methods: Fifteen samples were divided into three groups and subjected to bleaching and erosion treatment. Group I-treated with 30% hydrogen peroxide then treated with 1% citric acid solution; group II-treated with 30% hydrogen peroxide and a remineralizing agent followed by 1% citric acid solution; group III-without bleaching with 1% citric acid solution. Five samples per group, GI, GII, and GIII were subjected to the Vickers microhardness analysis. Loss of surface hardness loss (% SHL) was analyzed followed by one-way ANOVA test, post hoc multiple comparison test, Bonferroni test to compare the various group. Result: Group II showed the lowest % SHL after the erosive phase when compared with group I. Conclusion: Erosion which usually occurs as a consequence of bleaching can be minimized by the application of remineralizing agents after bleaching. How to cite this article: Chandrashekhar S, Mithare SS, Bharath M, et al. Determination of Microhardness of Remineralized Bleached Surface Subjected to Erosion-An In Vitro Study. Int J Clin Pediatr Dent 2023;16(1):97-100.

Defensive Mechanisms in Cucurbits against Melon Fly (Bactrocera cucurbitae) Infestation through Excessive Production of Defensive Enzymes and Antioxidants.

Melon fly (Bactrocera cucurbitae) is the most common pest of cucurbits, and it directly causes damage to cucurbit fruits in the early developmental stage. The infection of fruit tissues induces oxidative damage through increased generation of cellular reactive oxygen species. The effects of melon fly infestation on the production of defensive enzymes and antioxidant capabilities in five cucurbit species, namely, bottle gourd, chayote, cucumber, snake gourd, and bitter gourd, were investigated in this study. The total phenolic and flavonoid content was considerably higher in melon fly infestation tissues compared to healthy and apparently healthy tissues. The chayote and bottle gourd tissues expressed almost 1.5- to 2-fold higher phenolic and flavonoid contents compared to the tissues of bitter gourd, snake gourd, and cucumber upon infestation. Defensive enzymes, such as peroxidase (POD), superoxide dismutase (SOD), polyphenol oxidase (PPO), and catalase (CAT), were high in healthy and infected tissues of chayote and bottle gourd compared to bitter gourd, snake gourd, and cucumber. The activity of POD (60-80%), SOD (30-35%), PPO (70-75%), and CAT (40-50%) were high in infected chayote and bottle gourd tissue, representing resistance against infestation, while bitter gourd, snake gourd, and cucumber exhibited comparatively lower activity suggesting susceptibility to melon fly infection. The antioxidant properties were also high in the resistant cucurbits compared to the susceptible cucurbits. The current research has enlightened the importance of redox-regulatory pathways involving ROS neutralization through infection-induced antioxidative enzymes in host cucurbit resistance. The melon fly infestation depicts the possible induction of pathways that upregulate the production of defensive enzymes and antioxidants as a defensive strategy against melon fly infestation in resistant cucurbits.

Precursor to Gas Sensor: A Detailed Study of the Suitability of Copper Complexes as an MOCVD Precursor and their Application in Gas Sensing.

There are very few p-type semiconductors available compared to n-type semiconductors for positive sensing response for oxidizing gases and other important electronic applications. Cupric oxide (CuO) is one of the few oxides that show p-type conductivity, useful for sensing oxidizing gases. Many researchers obtained CuO using the chemical and solid-state routes, but uniformity and large-area deposition have been the main issues. Chemical vapor deposition is one such technique that provides control on several deposition parameters, which allow obtaining thin films having crystallinity and uniformity over a large area for the desired application. However, CuO-chemical vapor deposition (CVD) is still unfathomed due to the lack of suitability of copper precursors based on vapor pressure, contamination, and toxicity. Here, to address these issues, we have taken four Cu complexes (copper(II) acetylacetonate, copper(II) bis(2,2,6,6-tetramethyl-3,5-heptanedionato), copper(II) ethylacetoacetate, and copper(II) tert-butylacetoacetate), which are evaluated using thermogravimetry for suitability as a CVD precursor. The decomposition behavior of the complexes was also experimentally confirmed by depositing CuO thin films via CVD. Phase purity, decomposition, volatility, growth rate, and morphological characteristics of the films are investigated in detail. Analysis suggests that copper(II) tert-butylacetoacetate has the highest vapor pressure and growth rate at a low temperature, making it the most suitable precursor for high-throughput CVD. Further, to investigate the role of these precursors, films deposited using Cu complexes were subjected to gas sensing. The CuO gas sensor fabricated on glass shows pronounced NO2 sensing. The sensing results of CuO films have been explained from the standpoint of roughness, morphology, and unpassivated bonds present on the surface of films and vapor pressure of precursors. The higher density of surface state and the lower resistivity of the Cu(tbaoac)2 film lead to a sensor with higher responsivity and sensitivity (down to 1 ppm). These precursors can probably be utilized to improve the performance of other metal oxide gas sensors, especially Cu2O and Cu-III-O2.

Chemical vapor deposition of MoS2 layers from Mo-S-C-O-H system: thermodynamic modeling and validation.

A detailed thermodynamic analysis of the solid and gas phases of the Mo-S-C-O-H system used for large area chemical vapor deposition (CVD) of MoS2 is presented and compared with experimental results. Given the multivariable nature of the problem, excellent agreement is observed. Deviations, observed from thermodynamic predictions, mainly at low temperatures and high flow rates have been highlighted and discussed. CVD phase diagrams which predict parameter windows in which pure MoS2 can be synthesized have been provided for important gas phase chemistries. Pure H2 as a carrier gas is shown to facilitate the largest contamination free process window. CO presence is shown to significantly reduce the nucleation rate and enable large island sizes but at the cost of carbon contamination. Oxygen leaks are shown to result in sulphur contamination. The absence of H2S during cooling is shown to yield Mo due to the reduction of MoS2 by hydrogen. Oxidation of Mo causes oxide contamination.

A predictive approach to CVD of crystalline layers of TMDs: the case of MoS2.

Layered transition metal dichalcogenides (TMDs), such as MoS2, are candidate materials for next generation 2-D electronic and optoelectronic devices. The ability to grow uniform, crystalline, atomic layers over large areas is the key to developing such technology. We report a chemical vapor deposition (CVD) technique which yields n-layered MoS2 on a variety of substrates. A generic approach suitable to all TMDs, involving thermodynamic modeling to identify the appropriate CVD process window, and quantitative control of the vapor phase supersaturation, is demonstrated. All reactant sources in our method are outside the growth chamber, a significant improvement over vapor-based methods for atomic layers reported to date. The as-deposited layers are p-type, due to Mo deficiency, with field effect and Hall hole mobilities of up to 2.4 cm(2) V(-1) s(-1) and 44 cm(2) V(-1) s(-1) respectively. These are among the best reported yet for CVD MoS2.

Rapid, microwave-assisted synthesis of Gd2O3 and Eu:Gd2O3 nanocrystals: characterization, magnetic, optical and biological studies.

Ultra-small crystals of undoped and Eu-doped gadolinium oxide (Gd2O3) were synthesised by a simple, rapid microwave-assisted route, using benzyl alcohol as the reaction solvent. XRD, XPS and TEM analysis reveal that the as-prepared powder material consists of nearly monodisperse Gd2O3 nanocrystals with an average diameter of 5.2 nm. The nanocrystals show good magnetic behaviour and exhibit a larger reduction in relaxation time of water protons than the standard Gd-DTPA complex currently used in MRI imaging. Cytotoxicity studies (both concentration- and time-dependent) of the Gd2O3 nanocrystals show no adverse effect on cell viability, evidencing their high biological compatibility. Finally, Eu:Gd2O3 nanocrystals were prepared by a similar route and the red luminescence of Eu3+ activator ions was used to study the cell permeability of the nanocrystals. Red fluorescence from Eu3+ ions observed by fluorescence microscopy shows that the nanocrystals (Gd2O3 and Eu:Gd2O3) can permeate not only the cell membrane but can also enter the cell nucleus, rendering them candidate materials not only for MRI imaging but also for drug delivery when tagged or functionalized with specific drug molecules.

Tardive dyskinesia and deficit schizophrenia.

OBJECTIVE: Despite comparable antipsychotic exposure, some patients experience involuntary movements yet others do not. Negative symptoms have been associated with tardive dyskinesia (TD), but it is not certain whether this is an association with primary negative symptoms or the effects of medications. The aim of the present study was to determine whether patients with deficit schizophrenia (who have primary negative symptoms) are more likely to experience TD than those with non-deficit schizophrenia. METHOD: In 2006, all the people with a clinical diagnosis of schizophrenia in Nithsdale, Southwest Scotland, were identified using the 'key informant' method. These patients were categorized into those with and without the deficit syndrome and assessed for the presence of TD. Patients were also assessed for akathisia and extrapyramidal side effects. RESULTS: Of the 131 people assessed, 31 were categorized as having deficit schizophrenia (23.7%) and 100 people (76.3%) as non-deficit. There was no difference between the two groups with regard to age, antipsychotic exposure, and duration of illness. There was a significant association between deficit features and TD with an odds ratio = 2.97 [95% CI 1.128-6.88, P = 0.009]. CONCLUSION: Our findings support the proposal that the pathological process underlying deficit schizophrenia can predispose to the development of TD.

Bis(acetyl-acetonato-κO,O')(pyridine-κN)zinc(II).

In the title compound, [Zn(C(5)H(7)O(2))(2)(C(5)H(5)N)], the metal atom has square-pyramidal coordination geometry with the basal plane defined by the four O atoms of the chelating acetyl-acetonate ligands and with the axial position occupied by the pyridine N atom. The crystal packing is characterized by a C-H⋯O hydrogen-bonded ribbon structure approximately parallel to [10[Formula: see text]].

Multi-view methods for protein structure comparison using latent dirichlet allocation.

MOTIVATION: With rapidly expanding protein structure databases, efficiently retrieving structures similar to a given protein is an important problem. It involves two major issues: (i) effective protein structure representation that captures inherent relationship between fragments and facilitates efficient comparison between the structures and (ii) effective framework to address different retrieval requirements. Recently, researchers proposed vector space model of proteins using bag of fragments representation (FragBag), which corresponds to the basic information retrieval model. RESULTS: In this article, we propose an improved representation of protein structures using latent dirichlet allocation topic model. Another important requirement is to retrieve proteins, whether they are either close or remote homologs. In order to meet diverse objectives, we propose multi-viewpoint based framework that combines multiple representations and retrieval techniques. We compare the proposed representation and retrieval framework on the benchmark dataset developed by Kolodny and co-workers. The results indicate that the proposed techniques outperform state-of-the-art methods. AVAILABILITY: http://www.cse.iitm.ac.in/~ashishvt/research/protein-lda/. CONTACT: ashishvt@cse.iitm.ac.in.

Polygalacturonase inhibitor protein from fruits of anthracnose resistant and susceptible varieties of Chilli (Capsicum annuum L).

Chilli fruit is highly susceptible to anthracnose infection at the stage of harvest maturity, due to which the fruit yield in the leading commercial variety Byadgi is severely affected. Field studies on screening of several varieties for resistance to anthracnose have shown that a variety of chilli AR-4/99K is resistant to anthracnose infection. In many crops, resistance to fungal attack has been correlated with PGIP activity in developing fruits based on which transgenic varieties have been developed with resistance to fungi. The present study was carried out to determine whether anthracnose resistance in AR-4/99K was due to the increased levels of PGIP alone and/ or due to differences, if any, in the properties of PGIP. Hence, a comparative study of the properties of polygalacturonase inhibitor protein (PGIP) isolated from fruits of anthracnose resistant chilli var AR-4/99K and a susceptible variety Byadgi was conducted with the objective of utilizing the information in genetic transformation studies. Both the PGIPs from anthracnose resistant and susceptible varieties of chilli exhibited similarities in the elution pattern on Sephadex gel, DEAE cellulose, PAGE and SDS-PAGE. The two PGIPs were active over a wide range of pH and temperature. Both PGIPs showed differential inhibitory activity against polygalacturonase (PG) secreted by Colletotrichum gleosporoides, C. capsici, C. lindemuthianum, Fusarium moniliforme and Sclerotium rolfsii. The inhibitory activity of PGIP from both resistant and susceptible varieties was the highest (82% and 76%, respectively) against the PG from Colletotrichum capsici, a pathogen causing anthracnose rot of chilli, while the activity was lower (1.27 to 12.3%) on the other fungal PGs. Although PGIP activity decreased with fruit maturation in both the varieties, the resistant variety maintained a higher activity at 45 days after flowering (DAF) as compared to the susceptible variety which helped it to overcome the infection by anthracnose as against the susceptible variety (Byadgi) in which PGIP activity was drastically reduced at maturity. The molecular mass of PGIP as determined by SDS-PAGE was found to be 37 kDa. N-terminal sequence analysis of the PGIP showed the first six amino acid residues from N-terminal end were Asp-Thr-His-Lys-Ser-Glu (DTHKSE), respectively. The similarities in properties of the two PGIPs support the earlier findings that resistance of AR-4/99K to anthracnose fungus is a result of its higher PGIP activity at maturity.

Tris(methyl 3-oxobutanoato-κO,O')aluminium(III).

In the title compound, [Al(C(5)H(7)O(3))(3)], three acac-type ligands (methyl 3-oxobutanoate anions) chelate to the aluminium(III) cation in a slightly distorted AlO(6) octa-hedral coordination geometry. Electron delocalization occurs within the chelating rings.

Adducts of bis(acetylacetonato)zinc(II) with 1,10-phenanthroline and 2,2'-bipyridine.

In each of the zinc(II) complexes bis(acetylacetonato-kappa(2)O,O')(1,10-phenanthroline-kappa(2)N,N')zinc(II), [Zn(C(5)H(7)O(2))(2)(C(12)H(8)N(2))], (I), and bis(acetylacetonato-kappa(2)O,O')(2,2'-bipyridine-kappa(2)N,N')zinc(II), [Zn(C(5)H(7)O(2))(2)(C(10)H(8)N(2))], (II), the metal center has a distorted octahedral coordination geometry. Compound (I) has crystallographically imposed twofold symmetry, with Z' = 0.5. The presence of a rigid phenanthroline group precludes intramolecular hydrogen bonding, whereas the rather flexible bipyridyl ligand is twisted to form an intramolecular C-H...O interaction [the chelated bipyridyl ligand is nonplanar, with the pyridyl rings inclined at an angle of 13.4 (1) degrees]. The two metal complexes are linked by dissimilar C-H...O interactions into one-dimensional chains. The present study demonstrates the distinct effects of two commonly used ligands, viz. 1,10-phenanthroline and 2,2'-bipyridine, on the structures of metal complexes and their assembly.

Precursor chemistry for TiO2: titanium complexes with a mixed nitrogen/oxygen ligand sphere.

Novel mixed amido-malonato complexes of titanium are reported. The complexes were synthesized by partially replacing the amido groups from the complexes [Ti(NMe2)4] and [Ti(NEt2)4] via Brønstedt acid/base reactions, using the malonate-ligands di-isopropylmalonate (Hdpml) and di-tert-butylmalonate (Hdbml). Four representative complexes were synthesized and fully characterised by 1H NMR, 13C NMR, CHN analysis and mass spectrometry. The crystal structures of the six-coordinated complexes [Ti(NMe2)2(dbml)2] (3) and [Ti(NEt2)2(dbml)2] (4) are presented and discussed. The complexes are solids and the chemical and thermal characteristics of the complexes strongly depend on the substitution at the malonate ligand. While dpml containing complexes show a promising behaviour for classical MOCVD, dbml containing complexes seem to be more suitable for liquid injection-metal-organic chemical vapour deposition (LI-MOCVD). Based on its thermal characteristics, the most promising complex for thermal CVD, [Ti(NEt2)2(dpml)2] (2) was selected for preliminary MOCVD experiments, which indicate a good suitability for the deposition of TiO2 thin films.

Vascular cell attachment and procoagulant activity on metal alloys.

The attachment and growth of vascular smooth muscle cells on biomaterials used as components of devices implanted in the vascular space may influence the biocompatibility of such materials. The nature of the materials may affect the attachment and/or the activation of these cells' procoagulant responses. Therefore, the main objective of this study was to measure the strength of adhesion of these vascular cells to potential biomaterials (titanium, zirconium alloys, and stainless steel) by exposing them to a range of shear stresses (50-300 dyn cm(-2)) in a parallel plate flow chamber. The procoagulant responses of the cells were evaluated by measuring the tissue factor (TF) activity promoted by the different materials under flow conditions. The materials supported distinctly different levels of initial cell adhesion in static culture. However, the fraction of adherent cells did not decline significantly with incrementally increasing shear stress within the range tested. TF expression, as measured by factor Xa (FXa) production. was material-dependent. For example, cells cultured on Ti1313 exhibited more FXa production (13.2 nM 10(-5) cells) than Ti1313(DH) (8.5 nM 10(-5) cells) or stainless steel (2 nM 10(-5) cells). Thus, our studies indicate that the level of adhesion, strength of attachment and the expression of procoagulant activity of adherent vascular cells depend strongly on the nature of the underlying biomaterial.