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Smart response hydrogel has a broad application prospect in human health real-time monitoring due to its responses to a variety of stimuli. In this study, we developed a novel smart hydrogel dressing based on conductive MXene nanosheets and a temperature-sensitive PNIPAm polymer. γ-Methacryloxypropyltrimethoxysilane (KH570) was selected to functionalize the surface of MXene further to improve the interface compatibility between MXene and PNIPAm. Our prepared K-M/PNIPAm hydrogel was found to have a strain-sensitive property, as well as a respond to NIR phase change and volume change. When applied as a strain flexible sensor, this K-M/PNIPAm hydrogel exhibited a high strain sensitivity with a gauge factor (GF) of 4.491, a broad working strain range of ≈250%, a fast response of ∼160 ms, and good cycle stability (i.e., 3000 s at 20% strain). Besides, this K-M/PNIPAm hydrogel can be used as an efficient NIR light-controlled drug release carrier to achieve on-demand drug release. This work paved the way for the application of smart response hydrogel in human health real-time monitoring and NIR-controlled drug release functions.

The implementation of light-sensitive Pickering emulsions with spatio-temporal responsiveness in advanced applications like drug-delivery, colloidal or reaction engineering would open new avenues. However, curiously, light-sensitive Pickering emulsions are barely studied in the literature and their biocompatibility and/or degradability scarcely addressed. Thus, their development remains a major challenge. As an original strategy, we synthesized light-sensitive nanoparticles based on biocompatible Poly(NitroBenzylAcrylate) grafted dextran (Dex-g-PNBA) to stabilize O/W Pickering emulsions. The produced emulsions were stable in time and could undergo time and space-controlled destabilization under light stimulus. Irradiation time and alkaline pH-control of the aqueous phase were proved to be the actual key drivers of destabilization. As the nanoparticles themselves were photolyzed under light stimulus, possible harmful effects linked to accumulation of nanomaterials should be avoided. In addition to UV light (365 nm), visible light (405 nm) was successfully used for the spatio-temporal destabilization of the emulsions, offering perspectives for life science applications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The 3D printing of fluorescent materials could help develop, validate, and translate imaging technologies, including systems for fluorescence-guided surgery. Despite advances in 3D printing techniques for optical targets, no comprehensive method has been demonstrated for the simultaneous incorporation of fluorophores and fine-tuning of absorption and scattering properties. Here, we introduce a photopolymer-based 3D printing method for manufacturing fluorescent material with tunable optical properties. The results demonstrate the ability to 3D print various individual fluorophores at reasonably high fluorescence yields, including IR-125, quantum dots, methylene blue, and rhodamine 590. Furthermore, tuning of the absorption and reduced scattering coefficients is demonstrated within the relevant mamalian soft tissue coefficient ranges of 0.005-0.05 mm -1 and 0.2-1.5 mm -1 , respectively. Fabrication of fluorophore-doped biomimicking and complex geometric structures validated the ability to print feature sizes less than 200 μm. The presented methods and optical characterization techniques provide the foundation for the manufacturing of solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging., (© 2021. The Author(s).)

Hydrogels often have poor mechanical properties which limit their application in load-bearing tissues such as muscle and cartilage. In this work, a near-infrared light-triggered stretchable thermal-sensitive hydrogel with ultra-high drug loading was developed by a combination of natural polymeric nanocrystals, a network of synthetic thermo-responsive polymer, and magnetic Fe 3 O 4 nanoparticles. The hydrogels comprise cellulose nanocrystals (CNCs) decorated with Fe 3 O 4 nanoparticles (Fe 3 O 4 /CNCs) dispersed homogeneously in poly(N-isopropylacrylamide) (PNIPAm) networks. The composite hydrogels exhibit an extensibility of 2200%. Drug loading of vancomycin (VCM) reached a high value of 10.18 g g -1 due to the dispersion of Fe 3 O 4 /CNCs and the interactions between the CNCs and the PNIPAm network. Importantly, the hydrogels demonstrated a thermo-response triggered by NIR, with the temperature increasing from 26 to 41 °C within 60 s. The hydrogels have high biocompatibility evidenced by cell proliferation tests, illustrating that these hydrogels are promising as dressings for wound closure, and wound healing., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Cell sheet engineering represents a new era of precise and efficient regenerative medicine, but its efficacy is limited by the elaborative preparation and the weak mechanics. Herein, a near-infrared (NIR)-triggered dynamic wrinkling biointerface was designed for rapid acquisition of practical cell sheets. The biocompatible NIR can initiate the photothermal-mechanical linkage cascade to efficiently dissolve the collagen supporting layer and release the high-quality cell sheets. The interfacial shear force generates with the dynamic wrinkling, playing an active role in accelerating the cell sheet release. High-quality and self-supporting cell sheets can be harvested within a few minutes, demonstrating a new paradigm of photothermal-mechanical manipulation. The transplantable cell sheets with outstanding physiological and mechanical performances were proven to promote wound healing in skin regeneration. This method may open a completely new front in thermal and mechanical responsive cascade to harvest cell sheets, facilitating their wide applications in regenerative medicine.

Understanding the spatiotemporal effects of surface topographies and modulated stiffness and anisotropic stresses of hydrogels on cell growth remains a biophysical challenge. Here we introduce the photolithographic patterning or two-photon laser scanning confocal microscopy patterning of a series of o-nitrobenzylphosphate ester nucleic acid-based polyacrylamide hydrogel films generating periodically-spaced circular patterned domains surrounded by continuous hydrogel matrices. The patterning processes lead to guided modulated stiffness differences between the patterned domains and the surrounding hydrogel matrices, and to the selective functionalization of sub-regions of the films with nucleic acid anchoring tethers. HeLa cells are deposited on the circularly-shaped domains functionalized with the MUC-1 aptamers. Initiation of the hybridization chain reaction by nucleic acid tethers associated with the continuous hydrogel matrix results in stress-induced ordered orthogonal shape-changes on the patterned domains, leading to ordered shapes of cell aggregates bound to the patterns.

Here a CdS embedded poly acrylic acid (PAA)/graphene oxide (GO) polymeric composite was prepared for the efficient degradation of chlortetracycline (CTC) driven by visible light irradiation. The structure-activity relationship of GO/PAA-CdS was confirmed through the photocatalytic evaluation of a series of samples prepared by varying GO concentration, molar ratio of Cd:S and the amount of crosslinking agent. Through the composition, morphology, photoelectrochemical characterizations and degradation kinetic studies, it could be confirmed that the enhanced photocatalytic activity is attributed to the controlled growth of CdS nanoparticles by polymer net structure and effective electron transfer along GO nanosheets. The photodegradation of CTC was confirmed to be mainly governed by O 2 - and OH radicals generated from GO/PAA-CdS. The degradation intermediates of CTC were confirmed by LC-MS, and possible degradation pathways were proposed based on the prediction of radical attacking sites according to Fukui function values obtained through Density Functional Theory (DFT). Moreover, it was found that the catalytic activity of the photocatalyst was maintained after several cycles confirming the enhanced anti-photocorrosion of GO/PAA-CdS. This research provided an efficient approach by a novel photocatalyst for the removal of CTC from wastewater., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In order to improve the flame retardancy of polyacrylonitrile (PAN) fabrics, glycidyl methacrylate (GMA) was first grafted onto the surface of PAN fabric (PAN-g-GMA) by means of UV-induced photo grafting polymerization process. Then, PAN-g-GMA was chemically grafted with chitosan to obtain a bigrafted PAN fabric (PAN-g-GMA-g-CS). Finally, the flame-retardant PAN fabric (FR-PAN) was prepared by phosphorylation. The structure and elemental analysis of the samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal degradation properties and combustion characteristics of the fabrics were accessed by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and cone calorimeter (CC). The results show that the onset thermal decomposition temperature of FR-PAN fabric is lower than that of the control sample due to the degradation of the grafting groups. The combustion test indicates that the FR-PAN fabric has an excellent flame-retardant property and the combustion rate is significantly reduced. In addition, the char residue of the burned FR-PAN fabric is over 97%, indicating excellent char-forming ability., Competing Interests: The authors declare no conflict of interest.

A recent study has shown that the addition of ceramide to adhesive materials of medical sheets or tapes improves or maintains skin barrier functions despite the irritation and damage caused by the repeated removal of the sheet or tape. This fact may imply that ceramide molecules are released from the adhesive material and penetrate the skin. In this study, we investigated whether ceramide molecules are released from a UV-curable acrylic adhesive resin (acResin ® ) sheet containing ceramide molecules attached to a cultured skin sample by estimating the local ceramide concentration from the data obtained by synchrotron Fourier transform infrared micro-spectroscopy analysis. Since section samples of uniform thickness could not be prepared, the intensity data of the amide I peak originating from ceramide were normalized by using the intensity data of the ester peak originating from the resin matrix. This analysis enabled the quantification of the change in local ceramide concentrations in the sheet samples. This result indicates that ceramide molecules were released from the acResin ® sheet attached to the cultured skin sheet.

Developing high-performance oxygen barrier films using biomass-based materials is crucial for the development of green and sustainable society. Herein, we develop a strategy to synthesize polyacrylic acid-grafted-acryloyl/hemicellulose composites (PAA-g-AH) as film materials with excellent oxygen barrier property. The as-synthesized films were extensively characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), gel permeation chromatography (GPC), 1 H nuclear magnetic resonance ( 1 H NMR), mechanical test, light transmittance and oxygen transmission rate (OTR) measurement. All these testing results showed that the optimum film exhibit great oxygen barrier property with a low OTR value of 0.25 ± 0.01 cm 3 * μm/(m 2 *d*kPa), which was much lower than that of pure PAA film. Moreover, the hybrid films possess well mechanical strength, light transmittance and recycle usage properties. Experimental results indicated that the as-synthesized films have great potential applications in several fields as packaging materials, such as drug, food and electronic products., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The current challenge for polymeric nanoreactors is to precisely control the membrane permeability between permeable, impermeable, and semipermeable at defined pH. Additionally, the synthetic methods are obstructed by tedious purification processes, especially when polymer multiblocks are required in the membrane of capsules to achieve different responsiveness and functions. Here, we report a rapid one-pot synthesis of ABA-type triblock copolymer brushes on silica template via surface-initiated single electron transfer living radical polymerization (SI-SET-LRP). It is worth noting that there is no purification between the successive block formation steps, since each step is taken to full translation within 20 min. After removing the template, hollow capsules with cross-linked membrane are obtained and have been used as multiresponsive nanoreactors for enzymatic reactions. Their membrane permeability is triggered primarily by temperature and secondarily by pH to allow controlled enzymatic reactions to be reversibly addressable between "permeable", "semipermeable", and "impermeable" valve-like membrane status. These valve-like features highlight the significant potential of hollow capsules, for example, in the fields of synthetic biology and enzyme-deficient disease therapeutic applications.

Retrospective dosimetry is the method of using materials on or near a person who is exposed to ionizing radiation to determine the amount of radiation received by the person. A possible candidate material for retrospective dosimetry is Ivoclar Vivadent IPS e.max® CAD ceramic dental restoration material, which exhibits radiation-induced thermoluminescence when exposed to gamma- and x-ray radiation from a Cs source. The purpose of this paper is to characterize the material and study the behavior of the thermoluminescence signal with radiation dose and with delay time between radiation exposure and thermoluminescence measurement. The first glow peak is well-modeled by a first-order glow curve deconvolution formula. The height of the first glow peak is approximately linear with dose. The fading of the signal with time is approximately described by a power law curve with cutoff. The material appears to be suitable for retrospective radiation dosimetry.

Superabsorbent hydrogels based on polyacrylamide (PAAm) and Na-alginate (Alg) or chitosan (CS) were synthesized by γ-rays. The effect of dose and copolymer composition on gel content and water absorbency of PAAm/Alg, PAAm/CS and PAAm/Alg/CS hydrogels were studied. The gel content and water absorbency follows the order PAAm/Alg>PAAm/Alg/CS>PAAm/CS. The effect of different cations, fertilizers, buffers on water absorbency of the hydrogels was investigated. Water retention capability of swollen hydrogels as a function of time was studied. PAAm/Alg hydrogel has a high water retention capability. An application of the prepared hydrogels in agricultural fields was performed using maize plants. The results showed that the presence of hydrogels had growth promotion effect on quality and quantity of maize plants. The plants treated by PAAm/Alg hydrogels showed 50% increase in the grain yield suggesting their possible use as a soil conditioner and a water reservoir for plant-soil system., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Mechanical forces in the cell's natural environment have a crucial impact on growth, differentiation and behaviour. Few areas of biology can be understood without taking into account how both individual cells and cell networks sense and transduce physical stresses. However, the field is currently held back by the limitations of the available methods to apply physiologically relevant stress profiles on cells, particularly with sub-cellular resolution, in controlled in vitro experiments. Here we report a new type of active cell culture material that allows highly localized, directional and reversible deformation of the cell growth substrate, with control at scales ranging from the entire surface to the subcellular, and response times on the order of seconds. These capabilities are not matched by any other method, and this versatile material has the potential to bridge the performance gap between the existing single cell micro-manipulation and 2D cell sheet mechanical stimulation techniques.

Polyacrylic acid-grafted-carboxylic graphene/titanium nanotube (PAA-g-CGR/TNT) composite was synthesized. It was effectively used as adsorbent as well as photocatalyst. The composite was characterized by FTIR, XRD, SEM, TEM, Surface Area Analyzer, XPS and DRS. The photocatalytic activity of PAA-g-CGR/TNT composite was evaluated on the basis of the degradation of pollutants by using sunlight. The band gap of the prepared photocatalyst was found to be 2.6eV. The removal of the antibiotic enrofloxacin (ENR) was achieved by two step mechanism based on adsorption and photodegradation. The maximum adsorption was observed at pH 5.0. The best fitted kinetic model was found to be pseudo-second-order. The maximum adsorption was observed at 30°C. The maximum adsorption capacity was found to be 13.40mg/g. The kinetics of photodegradation of ENR onto PAA-g-CGR/TNT composite follow first-order kinetics and optimum pH was found to be 5.0. The regeneration and reuse of the adsorbent-cum-photocatalyst were also examined upto five cycles., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Burn wound management is a complex process because the damage may extend as far as the dermis which has an acknowledged slow rate of regeneration. This study investigates the feasibility of using hydrogel microparticles composed of bacterial cellulose and polyacrylamide as a dressing material for coverage of partial-thickness burn wounds. The microparticulate carrier structure and surface morphology were investigated by Fourier transform infrared, X-ray diffraction, elemental analysis, and scanning electron microscopy. The cytotoxicity profile of the microparticles showed cytocompatibility with L929 cells. Dermal irritation test demonstrated that the hydrogel was non-irritant to the skin and had a significant effect on wound contraction compared to the untreated group. Moreover, histological examination of in vivo burn healing samples revealed that the hydrogel treatment enhanced epithelialization and accelerated fibroblast proliferation with wound repair and intact skin achieved by the end of the study. Both the in vitro and in vivo results proved the biocompatibility and efficacy of hydrogel microparticles as a wound dressing material.

In vivo dosimetry is a greatly underutilized tool for patient safety in clinical external beam radiotherapy treatments, despite being recommended by several national and international organizations (AAPM, ICRU, IAEA, NACP). The reasons for this underutilization mostly relate to the feasibility and cost of in vivo dosimetry methods. Due to the increase in the number of beam angles and dose per fraction in modern treatments, there is a compelling need for a novel dosimeter that is robust and affordable while able to operate properly in these complex conditions. This work presents a gel patch dosimeter as a novel method of in vivo dosimetry. DEFGEL, a 6% T normoxic polyacrylamide gel, was injected into 1 cm thick acrylic molds to create 1 cm thick small cylindrical patch dosimeters. To evaluate the change in optical density due to radiation induced polymerization, dosimeters were scanned before and after irradiation using an in-house developed laser densitometer. The dose-responses of three separate batches of gel were evaluated and compared to check for linearity and repeatability. The response development time was evaluated to ensure that the patch dosimeter could be high throughput. Additionally, the potential of this system to be used as an in vivo dosimeter was tested with a clinically relevant end-to-end in vivo phantom test. All irradiations were performed with a Varian Clinac 21EX at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The dose-response of all three batches of gel was found to be linear within the range of 2-20 Gy. At doses below 0.5 Gy the statistical uncertainties were prohibitively large to make quantitative assessments of the results. The three batches demonstrated good repeatability in the range of 2 Gy to up to 10 Gy, with only slight variations in response at higher doses. For low doses the dosimeter fully developed within an hour while at higher doses they fully developed within four hours. During the in vivo phantom test the predicted patch absorbed dose was 4.23 Gy while the readout dose was evaluated to be 4.37 Gy, which corresponds to a 3.2% discrepancy. The dosimeter and densitometer pairing shows promise as an in vivo dosimetry system, especially for hypofractionated or MRI-guided radiotherapy treatments where higher doses are prescribed.

Background: The aims of this study were to compare the intensities of fluorescence emitted by different resin composites as detected using quantitative light-induced fluorescence (QLF) technology, and to compare the fluorescence intensity contrast with the color contrast between a restored composite and the adjacent region of the tooth., Methods: Six brands of light-cured resin composites (shade A2) were investigated. The composites were used to prepare composite discs, and fill holes that had been prepared in extracted human teeth. White-light and fluorescence images of all specimens were obtained using a fluorescence camera based on QLF technology (QLF-D) and converted into 8-bit grayscale images. The fluorescence intensity of the discs as well as the fluorescence intensity contrast and the color contrast between the composite restoration and adjacent tooth region were calculated as grayscale levels., Results: The grayscale levels for the composite discs differed significantly with the brand (p<0.001): DenFil (10.84±0.35, mean±SD), Filtek Z350 (58.28±1.37), Premisa (156.94±1.58), Grandio (177.20±0.81), Charisma (207.05±0.77), and Gradia direct posterior (211.52±1.66). The difference in grayscale levels between a resin restoration and the adjacent tooth was significantly greater in fluorescence images for each brand than in white-light images, except for the Filtek Z350 (p<0.05). However, the Filtek Z350 restoration was distinguishable from the adjacent tooth in a fluorescence image., Conclusions: The intensities of fluorescence detected from the resin composites varied. The differences between the composite and adjacent tooth were greater for the fluorescence intensity contrast than for the colors observed in the white-light images., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objective: To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco)., Methods: The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition., Results: As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA p<0.05). Although the KHN of SureFil SDR Flow was only marginally significantly different between the 2 and 6-mm thickness, the bottom at 6-mm was only 59% of the hardness measured at the top., Clinical Significance: This study highlights that clinicians need to consider how the depth of cure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objectives . To measure the temperature increase induced during thermocure lamp setting reaction of glass carbomer and to compare it with those induced by visible light curing of a resin-modified glass ionomer and a polyacid-modified composite resin in primary and permanent teeth. Materials and Methods . Nonretentive class I cavities were prepared in extracted primary and permanent molars. Glass carbomer (GC) was placed in the cavity and set at 60°C for 60 sn using a special thermocure lamp. Resin-modified glass ionomer (RMGIC) and polyacid-modified composite resin (PMCR) were placed in the cavities and polymerized with an LED curing unit. Temperature increases during setting reactions were measured with a J-type thermocouple wire connected to a data logger. Data were examined using two-way analysis of variance and Tukey's honestly significant difference tests. Results . The use of GC resulted in temperature changes of 5.17 ± 0.92°C and 5.32 ± 0.90°C in primary and permanent teeth, respectively ( p > 0.05). Temperature increases were greatest in the GC group, differing significantly from those in the PMCR group ( p < 0.05). Conclusion . Temperature increases during polymerization and setting reactions of the materials were below the critical value in all groups. No difference was observed between primary and permanent teeth, regardless of the material used., Competing Interests: The authors declare that they have no competing interests.

Objectives. The aim of this in vitro study was to assess thermal changes on tooth tissues during light exposure using two different LED curing units. The hypothesis was that no temperature increase could be detected within the dental pulp during polymerization irrespective of the use of a composite resin or a light-curing unit. Methods. Caries-free human first molars were selected, pulp residues were removed after root resection, and four calibrated type-J thermocouples were positioned. Two LED lamps were tested; temperature measurements were made on intact teeth and on the same tooth during curing of composite restorations. The data was analyzed by one-way analysis of variance (ANOVA), Wilcoxon test, Kruskal-Wallis test, and Pearson's χ (2). After ANOVA, the Bonferroni multiple comparison test was performed. Results. Polymerization data analysis showed that in the pulp chamber temperature increase was higher than that without resin. Starlight PRO, in the same condition of Valo lamp, showed a lower temperature increase in pre- and intrapolymerization. A control group (without composite resin) was evaluated. Significance. Temperature increase during resin curing is a function of the rate of polymerization, due to the exothermic polymerization reaction, the energy from the light unit, and time of exposure.

Harnessing a natural power source such as the human body temperature or sunlight should realize ultimate low-power devices. In particular, macroscale and flexible actuators that do not require an artificial power source have tremendous potential. Here we propose and demonstrate electrically powerless polymer-based actuators operated at ambient conditions using a packaging technique in which the stimulating power source is produced by heat from the human body or sunlight. The actuating angle, force, and reliability are discussed as functions of temperature and exposure to sunlight. Furthermore, a wearable device platform and a smart curtain actuated by the temperature of human skin and sunlight, respectively, are demonstrated as the first proof-of-concepts. These nature-powered actuators should realize a new class of ultimate low-power devices.

Purpose: The aim of this study was to investigate the effect of accelerated light aging on bond strength of a silicone elastomer to three types of denture resin., Materials and Methods: A total of 60 single lap joint specimens were fabricated with auto-, heat-, and photopolymerized (n = 20) resins. An addition-type silicone elastomer (Episil-E) was bonded to resins treated with the same primer (A330-G). Thirty specimens served as controls and were tested after 24 hours, and the remaining were aged under accelerated exposure to daylight for 546 hours (irradiance 765 W/m(2) ). Lap shear joint tests were performed to evaluate bond strength at 50 mm/min crosshead speed. Two-way ANOVA and Tukey's test were carried out to detect statistical significance (p < 0.05)., Results: ANOVA showed that the main effect of light aging was the most important factor determining the shear bond strength. The mean bond strength values ranged from 0.096 to 0.136 MPa. The highest values were recorded for auto- (0.131 MPa) and photopolymerized (0.136 MPa) resins after aging., Conclusions: Accelerated light aging for 546 hours affects the bond strength of an addition-type silicone elastomer to three different denture resins. The bond strength significantly increased after aging for photo- and autopolymerized resins. All the bonds failed adhesively., (© 2014 by the American College of Prosthodontists.)

Hydrogels such as poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) can be photopatterned to create a wide range of actuatable and self-folding microstructures. Mechanical motion is derived from the large and reversible swelling response of this cross-linked hydrogel in varying thermal or pH environments. This action is facilitated by their network structure and capacity for large strain. However, due to the low modulus of such hydrogels, they have limited gripping ability of relevance to surgical excision or robotic tasks such as pick-and-place. Using experiments and modeling, we design, fabricate, and characterize photopatterned, self-folding functional microgrippers that combine a swellable, photo-cross-linked pNIPAM-AAc soft-hydrogel with a nonswellable and stiff segmented polymer (polypropylene fumarate, PPF). We also show that we can embed iron oxide (Fe2O3) nanoparticles into the porous hydrogel layer, allowing the microgrippers to be responsive and remotely guided using magnetic fields. Using finite element models, we investigate the influence of the thickness and the modulus of both the hydrogel and stiff polymer layers on the self-folding characteristics of the microgrippers. Finally, we illustrate operation and functionality of these polymeric microgrippers for soft robotic and surgical applications.

The potential function of combining magnetic field (MF) pretreatment with cationic polyacrylamide (CPAM) additive on enhancing the dewaterability of waste-activated sludge was investigated in the present work. Two reactors were involved in a specially designed experimental apparatus, one of which was built with MF accessories. Several parameters were conducted, including CPAM dosages, MF strengths and processing times, respectively. Capillary suction time (CST) and specific resistance to filtration (SRF) were used to evaluate sludge dewaterability. Extracellular polymeric substances (EPS) concentration was also determined in an attempt to identify the observed changes in dewaterability. It was indicated by the results that both CPAM conditioning and MF pretreatment on sludge can lower CST and SRF values. However, subjecting to a combination of MF pretreatment and CPAM conditioning, sludge dewaterability was significantly enhanced beyond the level observed of CPAM addition alone. The lowest CST and SRF values of 36.5 s and 0.75×10(12) m kg(-1), respectively, were obtained when sludge was co-conditioned by CPAM (at a dosage of 40 mg L(-1)) and MF (at an induction of 40 mT) for 30 min, suggesting the optimal condition for enhancing sludge dewaterability. It is also shown from the significant correlations between EPS, protein, polysaccharide and CST/SRF that the increment of EPS concentration in sludge supernatant may be the major reason for the enhancement of dewaterability.

Purpose: To determine the dimensional stability of a poly(methyl methacrylate) (PMMA) acrylic resin when subjected to multiple sessions of repeated microwave irradiation at power settings of 700 and 420 W., Materials and Methods: Twenty standardized denture bases were fabricated using a PMMA resin. Points of measurement were marked on each denture base with a standardized template, and the distances between points were recorded using a digital microscope. The denture bases were randomly placed into two experimental groups of 10 bases each. Individual denture bases were placed into a glass beaker containing 200 ml of room temperature deionized water and then exposed to either 700 or 420 W of microwave radiation for 3 minutes. The denture bases were allowed to cool to room temperature, and measurements between points were recorded. This process was carried out for two microwave periods with measurements being completed after each period. The data were then analyzed for any significant changes in distances between points using a Student's t-test., Results: All denture bases experienced 1.0 to 2.0 mm or approximately 3% linear dimensional change after each period of microwaving. Results were significant with all t-tests having values of p < 0.05., Conclusion: This report showed that the denture bases deformed significantly under experimental conditions at either 700 W for 3 minutes in 200 ml of water or 420 W for 3 minutes in 200 ml of water., (© 2014 by the American College of Prosthodontists.)

The effect of polymerization cycles on flexural properties of conventional (Vipi Cril(®)-VC) or microwave-processed (Vipi Wave(®)-VW) denture base acrylic resins was evaluated. Specimens (n=10) were submitted to the cycles: WB=65ºC for 1 h+1 h boiling water (VC cycle); M630/25=10 min at 270 W+5 min at 0 W+10 min at 360 W (VW cycle); M650/5=5 min at 650 W; M700/4=4 min at 700 W; and M550/3=3 min at 550 W. Specimens were submitted to a three-point bending test at 5 mm/min until fracture. Flexural strength (MPa) and elastic modulus (GPa) data were analyzed by 2-way ANOVA/Tukey HSD (α=0.05). Overall, VC showed higher values than VW. The results obtained with microwave polymerization did not differ from those obtained with water-bath for both acrylic resins. The results observed when polymerization cycles using medium power and shorter time were used did not differ from those when manufacturer's recommended microwave cycle was applied. Conventional VC might be microwave-processed without compromising its flexural properties.

Hybrid (organic shell-inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range as a contrast enhancement mechanism for imaging the organic shells of such particles. We also study electron-beam-induced crystallization and amorphization of the shells and the formation of graphitic-like layers that contain both C and N. The resistance of the samples to irradiation by high-energy electrons, which is relevant for optical tuning and for understanding the degree to which such hybrid nanostructures are stable in the presence of biomedical radiation, is also discussed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Poly(acrylic acid) (PAA)-patterned polystyrene (PS) substrates were prepared by ion beam lithography to control cell behaviors of mouse fibroblasts and human embryonic kidney cells. Thin PAA films spin-coated on non-biological PS substrates were selectively irradiated with energetic proton ions through a pattern mask. The irradiated substrates were developed with deionized water to generate negative-type PAA patterns. The surface characteristics of the resulting PAA-patterned PS surface, such as surface morphology, chemical structure and composition and wettability, were investigated. Well-defined 100 μm PAA patterns were effectively formed on relatively hydrophobic PS substrates by ion beam lithography at higher fluences than 5 × 10(14) ions/cm(2). Moreover, based on the in vitro cell culture test, cells were adhered and proliferated favorably onto hydrophilic PAA regions separated by hydrophobic PS regions on the PAA-patterned PS substrates, and thereby leading to the formation of well-defined cell patterns.

Objectives: The study was aimed at evaluating, in vitro, cytotoxicity of four resin-based orthodontic cements (RBOC) as a function of degree of conversion (DC) and the light curing unit (LCU) employed on mouse fibroblast (L929)., Materials and Methods: Nine samples were manufactured for each group of cements using plasma-emulating light-emitting diode (LED) and conventional LED. Toxicity was assessed by immersing four specimens to culture medium (24 h/37°C) for extracting residual monomer or cytotoxic substance. Cell mitochondrial activity of L929 cell was evaluated using methyl tetrazolium (MTT) test. DC was evaluated by Fourier transform infrared spectroscopy for five samples., Results: Cements, LCUs, and interaction between cements and LCUs were found to play a statistically significant role in cytotoxicity (p < 0.0001). Opal band cement (OPAL) plasma LED was found noncytotoxic (90-100% cell viability). The other RBOC-LCU combinations were slightly cytotoxic (60-90% cell viability). Cements (p < 0.01) and LCUs (p < 0.05) had a statistically significant effect on DC. Conversely, interaction between cement and LCU had no statistically significant role on DC (p > 0.05). OPAL plasma LED displayed the highest levels of DC. The correlations between cell viability and DC were positive for three RBOCs., Conclusion: Therefore, high-intensity LCUs can be said to efficiently affect polymerization, so higher DC rates may achieve higher cell viability rates., Clinical Relevance: Cements and LCUs must be matched to each another to result in higher DC and maximal biocompatibility. Dual cure systems presented relatively high cell survival and higher DC, thus expressing superior to single-cure systems with plasma LED., (© The Author(s) 2014.)

Background: The aim of this study is to compare the microleakage of Class II dental composite resin restorations which have been cured by three different LED (light emitting diode) light curing modes compared to control samples cured by QTH (quartz tungsten halogen) light curing units (LCUs), to determine the most effective light curing unit and mode of curing., Results: In this experimental study, class II cavities were prepared on 100 sound human premolars which have been extracted for orthodontic treatment. The teeth were randomly divided into four groups; three experimental and one control group of 25 teeth each. Experimental groups were cured by either conventional, pulse-delay, or ramped curing modes of LED. The control group was cured for 20 seconds by QTH. The restorations were thermocycled (1000 times, between 5 and 55°C, for 5 seconds dwell time), dyed, sectioned mesio-distally and viewed under stereo-microscope (40×) magnification. Teeth were then scored on a 0 to 4 scale based on the amount of microleakage. The data were analyzed by Chi-square test.No significant difference was demonstrated between the different LCUs (light curing units), or modes of curing, at the enamel side (p > 0.05). At the dentin side, all modes of LED curing could significantly reduce microleakage (p < 0.05). The results suggest that slow start curing improves marginal integrity and seal. High intense curing endangers those aims., Conclusions: Comparison between the three LED mode cured composite resin restorations and QTH curing showed LED curing in all modes is more effective than QTH for reducing microleakage. Both LED and QTH almost completely eliminate the microleakage on the enamel side, however none of them absolutely eliminated microleakage on the dentin side.

Aim: This study investigated the effect of simulated microwave disinfection (SMD) on the linear dimensional changes, hardness and impact strength of acrylic resins under different polymerization cycles., Methdos: Metal dies with referential points were embedded in flasks with dental stone. Samples of Classico and Vipi acrylic resins were made following the manufacturers' recommendations. The assessed polymerization cycles were: A) water bath at 74 ºC for 9 h; B) water bath at 74 ºC for 8 h and temperature increased to 100 ºC for 1 h; C) water bath at 74 ºC for 2 h and temperature increased to 100 ºC for 1 h; and D) water bath at 120 ºC and pressure of 60 pounds. Linear dimensional distances in length and width were measured after SMD and water storage at 37 ºC for 7 and 30 days using an optical microscope. SMD was carried out with the samples immersed in 150 mL of water in an oven (650 W for 3 min). A load of 25 gf for 10 s was used in the hardness test. Charpy impact test was performed with 40 kpcm. Data were submitted to ANOVA and Tukey's test (5%)., Results: The Classico resin was dimensionally steady in length in the A and D cycles for all periods, while the Vipi resin was steady in the A, B and C cycles for all periods. The Classico resin was dimensionally steady in width in the C and D cycles for all periods, and the Vipi resin was steady in all cycles and periods. The hardness values for Classico resin were steady in all cycles and periods, while the Vipi resin was steady only in the C cycle for all periods. Impact strength values for Classico resin were steady in the A, C and D cycles for all periods, while Vipi resin was steady in all cycles and periods., Conclusion: SMD promoted different effects on the linear dimensional changes, hardness and impact strength of acrylic resins submitted to different polymerization cycles when after SMD and water storage were considered.

Failure of the bond between acrylic teeth and the denture base resin interface is one of the major concern in prosthodontics. The new generation of denture bases that utilize alternate polymerization methods are being introduced in the market. The aim of the study is to evaluate the influence of polymerization methods on bonding quality between the denture base and artificial teeth. Sixty test specimens were prepared (20 in each group) and were polymerized using heat, microwave and visible light curing. The tensile strength was recorded for each of the samples, and the results were analyzed statistically. The light-activated Eclipse™ System showed the highest tensile strength, followed by heat curing. The microwave-cured samples exhibited the least bonding to the acrylic teeth. Within the limitations of this study, it can be concluded that the new generation of light-cured denture bases showed significantly better bonding to acrylic teeth and can be used as an alternative to the conventional heat-polymerized denture base.

Transferring the implant position from the mouth to the definitive cast is one of the most critical steps in implant prosthodontics. To achieve a passive fit of the prosthesis, an accurate implant impression is crucial because discrepancies can induce both biologic and technical complications. Analysis of available research data suggests that a direct (pick-up) impression technique with splinted copings is the technique of choice, particularly for multiple implants. However, the traditional method of splinting the copings with autopolymerizing acrylic resin is a technique-sensitive and time- consuming procedure. This report describes a straightforward method of splinting impression copings with light-polymerizing acrylic resin, with minimal amount of autopolymerizing acrylic resin. The method also can be used to verify splinting accuracy., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Purpose: Debonding of acrylic teeth from the denture base remains a major problem in prosthodontics. The objective of this study was to evaluate the effect of various surface treatments on the shear bond strength of the two chemically different denture base resins-polymethyl methacrylate (PMMA) and urethane dimethacrylate (UDMA)., Materials and Methods: Two denture base resins, heat-cured PMMA (Meliodent) and light-activated UDMA (Eclipse), were used in this study. A total of 60 molar acrylic denture teeth were randomly separated into four groups (n = 15), according to surface treatment: acrylic untreated (group AC), Eclipse untreated (group EC), treated with eclipse bonding agent (group EB), and Er:YAG laser-irradiated eclipse (group EL). Shear bond strength test specimens were prepared according to the manufacturers' instructions. Specimens were subjected to shear bond strength test by a universal testing machine with a 1 mm/min crosshead speed. The data were analyzed with one-way ANOVA and post hoc Tukey-Kramer multiple comparison tests (α = 0.05)., Results: The highest mean bond strength was observed in specimens of group EB, and the lowest was observed in group EC specimens. A statistically significant difference in shear bond strength was found among all groups (p < 0.001), except between groups EC and EL (p = 0.61)., Conclusion: The two chemically different denture base polymers showed different shear bond strength values to acrylic denture teeth. Laser-irradiation of the adhesive surface was found to be ineffective on improving bond strength of acrylic denture teeth to denture base resin. Eclipse bonding agent should be used as a part of denture fabrication with the Eclipse Resin System., (© 2013 by the American College of Prosthodontists.)

The aim of this study is to assess the effect of additional curing procedures on the flexural strength and modulus of elasticity of indirect and direct composite materials. Twenty-four rectangular prism-shaped 2 mm x 2 mm x 25 mm samples of Belleglass, Premisa (Kerr), Adoro and Heliomolar (Ivoclar Vivadent) were prepared. Each composite was packed in an ad-hoc stainless steel device with a TeflonR instrument. A mylar strip and a glass slab were placed on top to obtain a flat surface. Polymerization was activated for 20 seconds with a halogen unit (Astralis 10, Ivoclar - Vivadent) with soft start regime and an output with a 350 to 1200 mw/cm2 range at four different points according to the diameter of the end of the guide. The specimens obtained were then randomly divided into two different groups: with and without additional treatment. In the group with additional treatment, the samples adorro were submitted to 25 minutes in Lumamat 100 (Ivoclar Vivadent) and the rest to 20 minutes in BelleGlass HP (Kerr). After the curing procedures, all samples were treated with sandpapers of decreasing grain size under water flow, and stored in distilled water for 24 h. Flexural strength was measured according to the ISO 404920 recommendations and elastic modulus was determined following the procedures of ANSI/ADA standard No. 27. Statistical differences were found among the different materials and curing procedures employed (P<0.01). The elastic modulus was significantly higher after the additional curing treatment for all materials except Premisa. Further work is needed to determine the association between the actual monomers present in the matrix and the effect of additional curing processes on the mechanical properties of both direct and indirect composites, and its clinical relevance.

Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations., Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-hardness (SMH) of dental resin composite., Design: Laboratory based, cross-sectional analytical study., Setting: Public and private dental clinics in Nairobi, Kenya., Subjects: Eighty three LCUs which were in use in private and public dental health facilities in Nairobi, Kenya and resin composite specimens., Results: Of the 83 LCUs studied, 43 (51.8%) were Light Emitting Diodes (LEDs) and 39(47.0%) were Quartz-Tungsten-Halogen (QTH) and 1 (1.2%) was Plasma Arc Curing (PAC) light. Mean light intensity for QTH and LED lights was 526.59 mW/cm2 and 493.67 mW/cm2 respectively (p=0.574), while the mean DOC for QTH lights was 1.71 mm and LED was 1.67 mm (p=0.690). Mean Vickers Hardness Number (VHN) for LED was 57.44 and for QTH was 44.14 (p=0.713). Mean light intensity for LCUs < or = 5 years was 596.03 mW/cm2 and 363.17 mW/cm2 for units > 5 years old (p=0.024). The mean DOC for the two age groups was 1.74 mm and 1.57 mm respectively (p=0.073). For SMH, the < or = 5 years and >5 years age groups gave a mean VHN of 58.81 and 51.46 respectively (p=0.1). On maintenance history, the frequency of routine inspection, duration since the last repair/replacement of a part or other maintenance activity and the nature of the last maintenance activity were determined and were not found to have influenced the light intensity, DOC and SMH., Conclusion: The LCU age has a statistically significant influence on its light intensity (p=0.024) while the type and maintenance history have no significant influence on its light intensity and composite DOC and SMH (p=0.574, p=0.690, p=0.713 respectively).

Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2) value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

The amidoximated polyacrylonitrile (PAN) fiber Fe complexes were prepared and used as the heterogeneous Fenton catalysts for the degradation of 28 anionic water soluble azo dyes in water under visible irradiation. The multiple linear regression (MLR) method was employed to develop the quantitative structure property relationship (QSPR) model equations for the decoloration and mineralization of azo dyes. Moreover, the predictive ability of the QSPR model equations was assessed using Leave-one-out (LOO) and cross-validation (CV) methods. Additionally, the effect of Fe content of catalyst and the sodium chloride in water on QSPR model equations were also investigated. The results indicated that the heterogeneous photo-Fenton degradation of the azo dyes with different structures was conducted in the presence of the amidoximated PAN fiber Fe complex. The QSPR model equations for the dye decoloration and mineralization were successfully developed using MLR technique. MW/S (molecular weight divided by the number of sulphonate groups) and NN=N (the number of azo linkage) are considered as the most important determining factor for the dye degradation and mineralization, and there is a significant negative correlation between MW/S or NN=N and degradation percentage or total organic carbon (TOC) removal. Moreover, LOO and CV analysis suggested that the obtained QSPR model equations have the better prediction ability. The variation in Fe content of catalyst and the addition of sodium chloride did not alter the nature of the QSPR model equations.

Purpose: The purpose of this study was to evaluate the effect of simulated disinfections (2% glutaraldehyde, 1% sodium hypochlorite, and microwave energy) on the surface hardness of Trilux, Biocler, Biotone, New Ace, and Magister commercial artificial teeth., Materials and Methods: Specimens (n = 10) were made with the teeth included individually in circular blocks of acrylic resin, leaving the labial surface exposed. Cycles of simulated chemical disinfection were accomplished with the specimens immersed in the solutions at room temperature for 10 minutes, followed by tap water washing for 30 seconds and storage in distilled water at room temperature for 7 days until the next disinfection. Simulated disinfection by microwave energy was carried out in a domestic oven with 1300 W at a potency of 50% for 3 minutes with the specimens individually immersed in 150 ml of distilled water. Control (no disinfection) and the experimental groups (first and third disinfection cycles) were submitted to Knoop hardness measurements with indentations at the center of the labial tooth surface. Data were submitted to repeated measure two-way ANOVA and Tukey's test (α = 0.05)., Results: Biocler, Magister, and Trilux showed lower surface microhardness when submitted to microwave. Lower microhardness for Biotone was promoted by hypochlorite, while no significant difference was shown for New Ace. The third disinfection cycle significantly decreased the tooth surface hardness only for microwave., Conclusions: Different disinfection methods promoted different effects on the microhardness of different types of artificial teeth. Surface microhardness of the teeth was less affected by the simulated chemical disinfections when compared to microwaved specimens., (© 2013 by the American College of Prosthodontists.)

The weathering of acrylic films and acrylic-coated lime wood (Tillia cordata Mill.) were examined using Fourier transform infrared (FT-IR) and two-dimensional infrared correlation spectroscopy. The obtained results showed chemical changes induced by exposure to weathering conditions, in both films and coated wood. The observed spectral changes of the acrylic films refer to the absorption band assigned to the C-O stretching, which progressively decreases with increasing exposure time. In the spectra of treated wood samples the main signal indicating the advance of oxidation during the photodegradation exposure is the gradual increase and broadening of the band in the carbonyl region. This is due to the formation of the non-hydrogen bonded aliphatic carboxylic acids and γ-lactone structures in the acrylic resin and of the nonconjugated ketones, carboxyl groups, and lactones in wood. As a consequence, the increase of the 1734 cm(-1) band is due to the degradation of lignin from wood surface. These observations are also supported by the decreased intensities of the bands at 1598 and 1505 cm(-1), assigned to C=C of aromatic skeletal (lignin). The relative intensity of the characteristic aromatic lignin band at 1505 cm(-1) decreases up to 25% of its original value after weathering, being less than half of the value obtained for uncoated wood. Two-dimensional infrared (2D IR) correlation spectroscopy was used to identify the sequence of the modifications of the different stretching vibrations bands under the weathering conditions, the method allowing the prediction of the order of degradation reactions. The acrylic resin degradation starts with the formation of radicals by abstraction of the tertiary hydrogen atoms of the methyl acrylate units and the α-CH3 groups from the ethyl methacrylate units. The subsequent decomposition and oxidation led to the formation of alcohol groups, hydroperoxides, ketones, and/or carboxylic acid groups. The 2D IR correlation spectra of weathered impregnated wood also revealed the elimination of low molecular weight compounds following the degradation of lignin and carbohydrates components from wood.

The purpose of this study was to validate the newly designed acrylic phantom for routine dosimetric purpose in radiotherapy. The phantom can be used to evaluate and compare the calculated dose and measured dose using film and gel dosimetric methods. In this study, a doughnut-shaped planning target volume (8.54 cm3) and inner organ at risk (0.353 cm3) were delineated for an IMRT test plan using the X-ray CT image of the phantom. The phantom consists of acrylic slabs which are integrated to form a human head with a hole in the middle where several dosimetric inserts can be positioned for measurement. An inverse planning with nine coplanar intensity-modulated fields was created using Pinnacle TPS. For the film analysis, EBT2 film, flatbed scanner, in-house developed MATLAB codes and ImageJ software were used. The 3D dose distribution recorded in the MAGAT gel dosimeter was read using a 1.5 T MRI scanner. Scanning parameters were CPMG pulse sequence with 8 equidistant echoes, TR = 5600, echo step = 22 ms, pixel size = 0.5 × 0.5, slice thickness = 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), R2 images were converted to dose images. The dose comparison was accomplished using in-house MATLAB-based graphical user interface named "IMRT3DCMP". For gel measurement dose grid from the TPS was extracted and compared with the measured dose grid of the gel. Gamma index analysis of film measurement for the tolerance criteria of 2%/2mm, 1%/1 mm showed more than 90% voxels pass rate. Gamma index analysis of 3D gel measurement data showed more than 90% voxels pass rate for different tolerance criteria of 2%/2 mm and 1%/1 mm. Overall both 2D and 3D measurement were in close agreement with the Pinnacle TPS calculated dose. The phantom designed is cost-effective and the results are promising, but further investigation is required to validate the phantom with other 3D conformal techniques for dosimetric purpose.

Background: The microwave energy is an efficient disinfection method; however, it can generate high temperatures that can result in distortion of the dentures., Objectives: To evaluate whether the addition of an enzymatic cleanser to microwave disinfection regimen would disinfect dentures with shorter irradiation time., Materials and Methods: Seven resin discs colonized with Candida albicans biofilm were placed on the palatal surface of sterile dentures to be randomly assigned to the following treatments: immersion in distilled water for 3 min with 0 (DW), 1 (DW + M1), 2 (DW + M2), or 3 min (DW + M3) of microwave irradiation; or immersion in denture cleanser for 3 min with 0 (DC), 1 (DC + M1), 2 (DC + M2) or 3 min (DC + M3) of irradiation. After the treatments, the viable cells were counted by a blinded examiner. The temperature was measured immediately after irradiation. The data were analyzed by ANOVA and Tukey post hoc tests (α = 0.05)., Results: No viable cells were found after DC + M2, DC + M3, and DW + M3 treatments, of which DC + M2 achieved the lowest temperature. No significant difference was found between the effectiveness of DW, DW + M1 and DC treatments (p > 0.05)., Conclusion: Within the limits of this study, the association of a denture cleanser and microwave energy is efficient to disinfect dentures in lower irradiation time and temperature., (© 2012 The Gerodontology Society and John Wiley & Sons A/S.)

Objective: This study evaluated the surface roughness (Ra) and color stability of acrylic resin colors (Lucitone 550, QC-20 and Vipi-Wave) used for fabricating bases for complete, removable dentures, overdentures and prosthetic protocol after immersion in chemical disinfectants (1% sodium hypochlorite and 2% peracetic acid) for 30 and 60 minutes., Material and Methods: Sixty specimens were made of each commercial brand of resin composite, and divided into 2 groups according to the chemical disinfectants. Specimens had undergone the finishing and polishing procedures, the initial color and roughness measurements were taken (t=0), and after this, ten test specimens of each commercial brand of resin composite were immersed in sodium hypochlorite and ten in peracetic acid, for 30 and 60 minutes, with measurements being taken after each immersion period. These data were submitted to statistical analysis., Results: There was evidence of an increase in Ra after 30 minutes immersion in the disinfectants in all the resins, with QC-20 presenting the highest Ra values, and Vipi-Wave the lowest. After 60 minutes immersion in the disinfectants all the resins presented statistically significant color alteration., Conclusions: Disinfection with 1% sodium hypochlorite and peracetic acid altered the properties of roughness and color of the resins., (© 2012 The Gerodontology Society and John Wiley & Sons A/S.)

Objective: To use ultrasonic measurements to monitor the effects of adhesive application and power density on the polymerization behavior of dual-cured core build-up resins., Methods: Ultrasonic measurements were carried out using a pulser-receiver, transducers and an oscilloscope. The core build-up resins were mixed, inserted into a transparent mold and then placed onto a sample stage with or without self-etch adhesive. Power densities of 0 (no light irradiation), 200 and 600 mW/cm(2) were used for curing. The transit time through the core build-up resin disk was divided by the specimen thickness to obtain the longitudinal sound velocity (V)., Results: Light irradiation of the core build-up resins at a power density of 600 mW/cm(2) caused V values to rise to an initial plateau of 1550-1650 m/s, then to rise rapidly to a second plateau of 2800-3200 m/s. The rate of V increase was slower when the resin cements were light-irradiated and became faster when irradiated at a higher power density. There were no significant differences between the groups with or without adhesive., Conclusions: The polymerization behavior of the core build-up resins was affected by the power density of the curing unit. The influence of adhesive application differed among the core build-up resins tested.

Aim: This study evaluated the effect of microwave irradiation as an alternative method for disinfection of different types of denture base acrylic resins., Methods: Twenty-four samples for each conventional, microwaved and characterized heat-cured acrylic resin were made and subjected to sterilization with ethylene oxide for the groups: 1) irradiated samples; 2) non-irradiated samples; and 3) samples without yeast. Each group was subdivided according to inoculation with C. albicans, C. dubliniensis and C. tropicalis. The samples were inoculated with 100 µL of inoculum of each species of Candida and later placed in an incubator at 37 °C for 1 hr to perform the first adhesion. After this time, each well was supplemented with sterile media and the plate was once again taken to a stove for incubation at 37 °C for 6 hr. The samples were immersed in 100 mL of sterile water and irradiated with microwave at 650 W for 3 min. Control samples were considered as the non-irradiated group. After incubation for 48 hr, irradiated and non-irradiated samples were subjected to a digital colony counter., Results: Control group (non-irradiated) showed microbial growth for resins and the means of ufc/mL were without statistically significant differences. Microwave irradiated samples (experimental group) promoted no viable colonies for all Candida species and types of acrylic resins. The means of ufc/mL were without statistically significant differences., Conclusion: Microwave irradiation was an effective method for disinfection of the acrylic resins inoculated with C. albicans, C. dubliniensis and C. tropicalis.

Objective: To prepare, characterize, and analyze the release behavior of bleomycin-loaded magnetite nanoparticles (BLM-MNPs) coated with polyacrylic acid (PAA) as a new drug delivery system that can be specifically distributed in the tumor site., Methods: BLM-MNPs coated with PAA were prepared using a solvothermal approach. The particles were characterized using scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The loading and release behaviors of BLM-MNPs were examined by a mathematical formula and in vitro release profile at pH 7.5., Results: The sphere Fe3O4 nanoparticles with the size of approximately 30 nm exhibit a saturation magnetization of 87 emu/g. The noncoordinated carboxylate groups of PAA confer on the good dispersibility in the aqueous solution and lead to a good loading efficiency of BLM reaching 50% or higher. Approximately 98% of immobilized BLM could be released within 24 h, of which 22.4% was released in the first hour and then the remaining was released slowly and quantitatively in the next 23 hours., Conclusion: BLM-MNPs were prepared and characterized successfully. The particles show high saturation magnetization, high drug loading capacity, and favorable release property, which could contribute to the specific delivery and controllable release of BLM, and the BLM-MNPs could be a potential candidate for the development of treating solid tumors.

Polyacrylonitrile(PAN)/manganese acetate(Mn(CH(3)COO)(2)) composite nanofibers have been fabricated by electrospinning, a simple and effective technology. The obtained composite nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR). The composite nanofibers are amorphous in structure, continuous, even and smooth. At the same time, the reduction performance of Cr(VI) by oxalic acid in the presence of the composite nanofibers is also investigated. The results indicate that the composite nanofibers have exhibited excellent catalysis performance for Cr(VI) reduction from a Cr(2)O(7)(2-)-containing solution by oxalic acid. And the critical parameters, such as the catalyst dosage, oxalic acid content, chromium concentration, the pH value of the reaction solution and light have important impact on the reduction process. Under the simulated solar light irradiation, after only 60 min, 1.2mM initial Cr(VI) solution was reduced absolutely in the presence of PAN/Mn(CH(3)COO)(2) composite nanofibers containing 17.5 wt.% Mn(CH(3)COO)(2) by 0.3 mL 0.5M oxalic acid. In light, the reduction of Cr(VI) by oxalic acid is markedly accelerated., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The bond strength of resin composite to Er,Cr:YSGG laser-irradiated enamel and dentin has been evaluated in only a few studies. Therefore, we measured and compared the micro-shear bond strength of composite restorations to enamel and dentin using two different cavity-preparation tools and conditioning methods. One hundred and seventy-five caries-free human third molars were sectioned longitudinally into two different thicknesses and randomly assigned to seven subgroups (n = 25). Enamel groups included laser-cut without etching (LO), laser-cut and laser-etched (LL), laser-cut and acid-etched (LA), bur-cut and laser-etched (BL1), and bur-cut and acid-etched (BA1-comparison group). Dentinal groups included bur-cut and laser-etched (BL2) and bur-cut and acid-etched (BA2-comparison group). The specimens were bonded by Single Bond and Tygon tubes and were restored with Z100 composite. Failure patterns were evaluated using a stereomicroscope, and a shear bond test was performed at 0.5 mm/min. The mean shear bond strength values (MPa) for the LO, LL, LA, BL1 and BA1 enamel groups were 23.14, 23.77, 23.51, 19.30, and 28.99, respectively, whereas for the BL and BA dentinal groups, these values were 22.44 and 26.15, respectively. In enamel specimens, BA1 and LL groups presented the highest shear bond strength values, and the bur-cut and laser-etched (BL1) group showed the lowest values. In the laser-etched groups, bond strength values for bur-cut surfaces were significantly higher than those for laser-cut surfaces. Moreover, there was a significant difference between the BL2 and BA2 dentinal groups. The results of this study indicate that re-etching with acid phosphoric would be recommended if an Er,Cr:YSGG laser is used for tooth preparation or surface treatment.

The aim of this work is to evaluate the effect of surface treatment with Er:YAG and Nd:YAG lasers on resin composite bond strength to recently bleached enamel. In this study, 120 bovine incisors were distributed into two groups: group C: without bleaching treatment; group B: bleached with 35% hydrogen peroxide. Each group was divided into three subgroups: subgroup N: without laser treatment; subgroup Nd: irradiation with Nd:YAG laser; subgroup Er: irradiation with Er:YAG laser. The adhesive system (Adper Single Bond 2) was then applied and composite buildups were constructed with Filtek Supreme composite. The teeth were sectioned to obtain enamel-resin sticks (1 × 1 mm) and submitted to microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. The bond strength values in the bleached control group (5.57 MPa) presented a significant difference in comparison to the group bleached and irradiated with Er:YAG laser (13.18 MPa) or Nd:YAG (25.67 MPa). The non-bleached control group presented mean values of 30.92 MPa, with statistical difference of all the others groups. The use of Nd:YAG and Er:YAG lasers on bleached specimens was able to improve the bond strengths of them.