Biomimetic piezoelectric nanomaterial-modified oral microrobots for targeted catalytic and immunotherapy of colorectal cancer

Lactic acid (LA) accumulation in the tumor microenvironment poses notable challenges to effective tumor immunotherapy. Here, an intelligent tumor treatment microrobot based on the unique physiological structure and metabolic characteristics of Veillonella atypica (VA) is proposed by loading Staphylococcus aureus cell membrane-coating BaTiO3 nanocubes (SAM@BTO) on the surface of VA cells (VA-SAM@BTO) via click chemical reaction. Following oral administration, VA-SAM@BTO accurately targeted orthotopic colorectal cancer through inflammatory targeting of SAM and hypoxic targeting of VA. Under in vitro ultrasonic stimulation, BTO catalyzed two reduction reactions (O2 → •O2- and CO2 → CO) and three oxidation reactions (H2O → •OH, GSH → GSSG, and LA → PA) simultaneously, effectively inducing immunogenic death of tumor cells. BTO catalyzed the oxidative coupling of VA cells metabolized LA, effectively disrupting the immunosuppressive microenvironment, improving dendritic cell maturation and macrophage M1 polarization, and increasing effector T cell proportions while decreasing regulatory T cell numbers, which facilitates synergetic catalysis and immunotherapy.

[Effect of asiaticoside on systolic blood pressure and relaxation of isolated thoracic aorta of rats]

OBJECTIVE

To investigate the effect of asiaticoside on blood pressure and relaxation of thoracic aorta in rats and explore the underlying mechanism.

METHODS

SD rats treated with 50 and 100 mg/kg asiaticoside by daily gavage for 2 weeks were monitored for systolic blood pressure changes, and histological changes of the thoracic aorta were evaluated using HE staining. In isolated rat endothelium-intact and endothelium-denuded thoracic aorta rings, the effects of asiaticoside on relaxation of the aortic rings were tested at baseline and following norepinephrine (NE)- and KCl-induced constriction. The vascular relaxation effect of asiaticoside was further observed in NE-stimulated endothelium-intact rat aortic rings pretreated with L-nitroarginine methyl ester, indomethacin, zinc protoporphyrin Ⅸ, tetraethyl ammonium chloride, glibenclamide, barium chloride, Iberiotoxin, 4-aminopyridine, or TASK-1-IN-1. The aortic rings were treated with KCl and NE followed by increasing concentrations of CaCl2 to investigate the effect of asiaticoside on vasoconstriction induced by external calcium influx and internal calcium release.

RESULTS

Asiaticoside at 50 and 100 mg/kg significantly lowered systolic blood pressure in rats without affecting the thoracic aorta histomorphology. While not obviously affecting resting aortic rings with intact endothelium, asiaticoside at 100 mg/kg induced significant relaxation of the rings constricted by KCl and NE, but its effects differed between endothelium-intact and endothelium-denuded rings. In endothelium-intact aortic rings pretreated with indomethacin, ZnPP Ⅸ, barium chloride, glyburide, TASK-1-IN-1 and 4-aminopyridine, asiaticoside did not produce significant effect on NE-induced vasoconstriction, and tetraethylammonium, Iberiotoxin and L-nitroarginine methyl ester all inhibited the relaxation effect of asiaticoside. In KCland NE-treated rings, asiaticoside obviously inhibited CaCl2-induced vascular contraction.

CONCLUSION

Asiaticoside induces thoracic aorta relaxation by mediating high-conductance calcium-activated potassium channel opening, promoting nitric oxide release from endothelial cells and regulating Ca2+ influx and outflow, thereby reducing systolic blood pressure in rats.

Development of a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop detection of microplastics in environmental and biological samples

Current techniques for microplastics (MPs) analysis are diverse. However, most techniques have individual limitations like the detection limit of spatial resolution, susceptibility, high cost, and time-consuming detection. In this study, we proposed a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop MPs detection, in which barium fluoride was used as the substrate alternative to the filter membrane. Compared with commonly used filter membranes (alumina, silver, PTFE and nylon membranes), the barium fluoride substrate showed better spectroscopic detection performance on microscopic observation, broader transmittable wavenumber range for μ-FTIR (750-4000 cm-1) and μ-Raman (250-4000 cm-1) detection, thus suitable for the multi-spectroscopy analysis of spiked samples. Further, the real environmental and biological samples (indoor air, bottled water and human exhaled breath) were collected and detected to verify the applicability of the developed multi-spectroscopy method. The results indicated that the average content of detected MPs could be increased by 30.4 ± 29.9 % for indoor air, 17.1 ± 13.2 % for bottled water and 38.4 ± 16.0 % for human exhaled breath, respectively in comparison with widely used μ-Raman detection, which suggested that MPs exposure might be underestimated using single spectroscopy detection. Moreover, the majority of underestimated MPs were colored and smaller sized (<50 μm) MPs, which could pose higher risks to human body. In addition, the proposed method consumed lower sample pre-treatment costs and was environmental-friendly since the barium fluoride substrate could be used repeatedly after being cleaned by organic solvent with reliable results (n = 10, CV = 10 %, ICC = 0.961), which reduced the cost of MPs detection by at least 2.49 times compared with traditional methods using silver membrane.

Composition-driven morphological evolution of BaTiO3 nanowires for efficient piezocatalytic hydrogen production

Hydrogen production from water by piezocatalysis is very attractive owing to its high energy efficiency and novelty. BaTiO3, a highly piezoelectric material, is particularly suitable for this application due to its high piezoelectric potential, non-toxic nature, and physicochemical stability. Owing to the critical role of morphology on properties, one-dimensional (1D) materials are expected to exhibit superior water-splitting performance and thus there is a need to optimise the processing conditions to develop outstanding piezocatalysts. In the present work, piezoelectric BaTiO3 nanowires (NWs) were hydrothermally synthesised with precursor Ba:Ti molar ratios of 1:1, 2:1, and 4:1. The morphology, defect chemistry, and hydrogen evolution reaction (HER) efficiency of the as-synthesised BaTiO3 NWs were systematically investigated. The results showed that the morphological features, aspect ratio, structural stability and defect contents of the 1D morphologies collectively have a significant impact on the HER efficiency. The morphological evolution mechanism of the 1D structures were described in terms of ion exchange and dissolution-growth processes of template-grown BaTiO3 NWs for different Ba:Ti molar ratios. Notably, the BaTiO3 NWs synthesised with Ba:Ti molar ratio of 2:1 displayed high crystallinity, good defect concentrations, and good structural integrity under ultrasonication, resulting in an outstanding HER efficiency of 149.24 μmol h-1g-1 which is the highest obtained for nanowire morphologies. These results highlight the importance of synthesis conditions for BaTiO3 NWs for generating excellent piezocatalytic water splitting performance. Additionally, post-ultrasonication tested BaTiO3 NWs demonstrated unexpected photocatalytic activity, with the BTO-1 sample (1:1 Ba:Ti) exhibiting 56% photodegradation of RhB in 2 h of UV irradiation.

Tunable Artificial Relaxor Behavior in [BaTiO_{3}]_{m}/[BaZrO_{3}]_{n} Superlattices

[BaTiO_{3}]_{m}/[BaZrO_{3}]_{n} (m, n=4-12) superlattices are used to demonstrate the fabrication and deterministic control of an artificial relaxor. X-ray diffraction and atomic-resolution imaging studies confirm the production of high-quality heterostructures. With decreasing BaTiO_{3} layer thickness, dielectric measurements reveal systematically lower dielectric-maximum temperatures, while hysteresis loops and third-harmonic nonlinearity studies suggest a transition from ferroelectriclike to relaxorlike behavior driven by tuning the random-field strength. This system provides a novel platform for studying the size effect and interaction length scale of the nanoscale-polar structures in relaxors.

Membrane reactor based synthesis of biodiesel from Toona ciliata seed oil using barium oxide nano catalyst

Membrane technology has been embraced as a feasible and promising substitute to the traditional technologies employed for biodiesel synthesis which are energy and time consuming. It needs less energy, has high stability, is environmentally friendly, and is simple to operate and control. Therefore, in our current study membrane technology was employed to synthesize biodiesel from Toona ciliate novel and non-edible seed oil. Since Toona ciliata has affluent oil content (33.8%) and is effortlessly and extensively available. In fact, we intended to scrutinize the effects of green synthesized barium oxide nanoparticles for one step transesterification of biodiesel production using membrane technology followed by characterization of prepared catalyst via innovative techniques. Optimal yield of biodiesel attained was 94% at 90 °C for 150 min with methanol to oil molar ratio of 9:1 and amount of about 0.39 wt %. Quantitative analysis of synthesized Toona ciliata oil biodiesel was carried out by advance techniques of Gas chromatography mass spectrometry (GC-MS), Fourier-transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) which authorize the synthesis of fatty acid methyl ester compounds using oil from Toona ciliata seeds. Values of Toona ciliata fuel properties for instance flash point (70°C), density (0.89 kg/m³), viscosity (5.25 mm²/s), cloud point (-8°C) and pour point (-11°C) met the specifications of international standards i. e American (ASTM D-6751), European (EN-14214) and China (GB/T 20,828). Subsequently, it is concluded that membrane technology is environmentally friendly and efficient technique for mass-production of sustainable biodiesel using green nano catalyst of barium oxide.

Metabolism of barium in the human body after suicidal ingestion: A CARE-compliant case report

RATIONALE

Thus far, barium poisoning has been seldom reported and the metabolism of barium in human body has not been explored.

PATIENT CONCERNS

A 21-year-old young man was taken to the local hospital by "120 emergency medical services" after a suicidal attempt. About 100 mL of barium chloride solution with a concentration of 100 g/L was ingested, while the actual amount of ingested barium chloride solution was unclear because of immediate vomiting after the ingestion.

DIAGNOSES

About 2 hours after the suicidal ingestion, the patient was presented with somnolence, the pulse rate was 67 beats per minute, the blood pressure was 158/92 mm Hg, but he exhibited no nausea or vomiting. About 3 hours after the ingestion, the blood concentration of potassium was 1.5 mmol/L.

INTERVENTIONS

The patient received gastric lavage by magnesium sulfate solution, intravenous sodium thiosulfate, and potassium supplementation. Other symptomatic treatments were applied simultaneously. To investigate the metabolism of barium in the human body, we measured the concentration of barium in 9 groups of paired serum and urine samples sequentially collected from the patient.

OUTCOMES

The patient was rescued successfully.

LESSONS

The serum concentration of barium decreased rapidly in the first 24 hours. In this period, prompt and massive potassium supplementation and other symptomatic treatments are effective and recommended.

The impact of ionic contribution to dielectric permittivity in 11CB liquid crystal and its colloids with BaTiO3 nanoparticles

The report shows the temperature behavior of the real part of dielectric permittivity in the static (dielectric constant) and low-frequency (LF) domains in bulk samples of 11CB and its BaTiO₃-based nanocolloids. The study covers the isotropic liquid (I), nematic (N), smectic A (SmA), and solid crystal (Cr) phases. For each phase, the dominance of pretransitional fluctuations, significantly moderated by nanoparticles, is shown. The authors consider separate focuses on the dielectric constant [Formula: see text] evolution in the static domain, yielding mainly response from permanent dipole moment and its arrangement, and in the low-frequency (LF) domain [Formula: see text] (where [Formula: see text] is for the real part of dielectric permittivity in the LF domain), which is associated solely with ionic-related polarization mechanisms. All of these led to new experimental evidence concerning I-N, N-SmA, and SmA-solid transitions, focusing on the strength and extent of pretransitional effects, critical exponents, and phase transitions discontinuities. The strong evidence for pretransitional effects near the SmA-Cr transition is notable, particularly regarding [Formula: see text]. Studies are supplemented by the discussion of DC electric conductivity-a parameter also related to the LF domain. Finally, the validity of the relation [Formula: see text] (where f stands for frequency, and A is a constant parameter), often used for discussing dielectric spectra in LC compound and its nanocolloids in the LF domain, is examined.

Biocompatibility and colorectal anti-cancer activity study of nanosized BaTiO3 coated spinel ferrites

In the present work, different nanoparticles spinel ferrite series (MFe2O4, Co0.5M0.5Fe2O4; M = Co, Mn, Ni, Mg, Cu, or Zn) have been obtained via sonochemical approach. Then, sol-gel method was employed to design core-shell magnetoelectric nanocomposites by coating these nanoparticles with BaTiO3 (BTO). The structure and morphology of the prepared samples were examined by X-ray powder diffraction (XRD), scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscope (HR-TEM), and zeta potential. XRD analysis showed the presence of spinel ferrite and BTO phases without any trace of a secondary phase. Both phases crystallized in the cubic structure. SEM micrographs illustrated an agglomeration of spherical grains with nonuniformly diphase orientation and different degrees of agglomeration. Moreover, HR-TEM revealed interplanar d-spacing planes that are in good agreement with those of the spinel ferrite phase and BTO phase. These techniques along with EDX analyses confirmed the successful formation of the desired nanocomposites. Zeta potential was also investigated. The biological influence of (MFe2O4, CoMFe) MNPs and core-shell (MFe2O4@BTO, CoMFe@BTO) magnetoelectric nanocomposites were examined by MTT and DAPI assays. Post 48 h of treatments, the anticancer activity of MNPs and MENCs was investigated on human colorectal carcinoma cells (HCT-116) against the cytocompatibility of normal non-cancerous cells (HEK-293). It was established that MNPs possess anti-colon cancer capability while MENCs exhibited a recovery effect due to the presence of a protective biocompatible BTO layer. RBCs hemolytic effect of NPs has ranged from non- to low-hemolytic effect. This effect that could be attributed to the surface charge from zeta potential, also the CoMnFe possesses the stable and lowest zeta potential in comparison with CoFe2O4 and MnFe2O4 also to the protective effect of shell. These findings open up wide prospects for biomedical applications of MNPs as anticancer and MENCs as promising drug nanocarriers.

Collaborative Filler Network for Enhancing the Performance of BaTiO3/PDMS Flexible Piezoelectric Polymer Composite Nanogenerators

Wearable sensors are gaining attention in human health monitoring applications, even if their usability is limited due to battery need. Flexible nanogenerators (NGs) converting biomechanical energy into electrical energy offer an interesting solution, as they can supply the sensors or extend the battery lifetime. Herein, flexible generators based on lead-free barium titanate (BaTiO₃) and a polydimethylsiloxane (PDMS) polymer have been developed. A comparative study was performed to investigate the impact of multiwalled carbon nanotubes (MWCNTs) via structural, morphological, electrical, and electromechanical measurements. This study demonstrated that MWCNTs boosts the performance of the NG at the percolation threshold. This enhancement is attributed to the enhanced conductivity that promotes charge transfer and enhanced mechanical property and piezoceramics particles distribution. The nanogenerator delivers a maximum open-circuit voltage (V_OC) up to 1.5 V and output power of 40 nW, which is two times higher than NG without MWCNTs. Additionally, the performance can be tuned by controlling the composite thickness and the applied frequency. Thicker NG shows a better performance, which enlarges their potential use for harvesting biomechanical energy efficiently up to 11.22 V under palm striking. The voltage output dependency on temperature was also investigated. The results show that the output voltage changes enormously with the temperature.

Antifouling BaTiO3/PVDF piezoelectric membrane for ultrafiltration of oily bilge water

Barium titanate/polyvinylidene fluoride (BaTiO₃/PVDF) piezoelectric membrane was successfully prepared and generated in-situ vibrations to reduce membrane fouling by applying alternating current (AC) signal for oily bilge water ultrafiltration. The effect of in-situ vibration on membrane fouling was investigated through changing in the excitation alternating voltage and its frequency, pH, crossflow rate. The results indicated that the piezoelectric membrane by applying AC signal remarkably alleviated the membrane fouling for bilge water ultrafiltration. The membrane fouling decreased with increasing the AC signal voltage. The final steady-state permeate flux from the piezoelectric membrane for bilge water ultrafiltration increased with the AC signal voltage, raising it by up to 63.4% at AC signal voltage of 20 V compared to that of the membrane without applying AC voltage. The high permeate flux was obtained at the resonant frequency of 220 kHz. During the 50-h ultrafiltration of bilge water with the piezoelectric membrane excited at 220 kHz and 15 V, the permeate flux from the membrane was stable. The oil concentration in outflow from the piezoelectric membrane was below 14 ppm, which met the discharged level required by IMO convention. The total organic carbon removal rate in bilge water was over 94%.

Ferroelectric-semiconductor BaTiO3-Ag2O nanohybrid as an efficient piezo-photocatalytic material

Piezo-photocatalysis is a new concept of utilizing nanohybrids comprising piezoelectric and photocatalytic materials for enhancement in advanced oxidation process under the presence of light and mechanical energy. In this study, we explored the effectiveness of piezo-photocatalysis via examining their catalytic activity towards the degradation of azo dye (Rhodamine-B) and standard pollutant (Phenol) catalyzed by ferroelectric-semiconductor (BaTiO₃-Ag₂O) nanohybrids. Further, the enhancement in piezo-photocatalysis has been achieved via persulfate activation and the role of free radicals was examined by quenchers. A plausible mechanism for the improved piezo-photocatalysis of BaTiO₃-Ag₂O nanohybrid using persulfate activation has been discussed in detail. The removal mechanism of Rhodamine-B has been investigated using analytical techniques such as HPLC and EPR. Our experimental study demonstrated that the combination of piezo-photocatalysis with persulfate activation will provide higher reaction rate which will be beneficial towards the degradation of complex molecular pollutants derived from industrial sectors.

Electrical waveform dependent osteogenesis on PVDF/BaTiO3 composite using a customized and programmable cell stimulator

Directing cellular functionalities using biomaterial-based bioelectronic stimulation remains a significant constraint in translating research outcomes to address specific clinical challenges. Electrical stimulation is now being clinically used as a therapeutic treatment option to promote bone tissue regeneration and to improve neuromuscular functionalities. However, the nature of the electrical waveforms during the stimulation and underlying biophysical rationale are still not scientifically well explored. Furthermore, bone-mimicking implant-based bioelectrical regulation of osteoinductivity has not been translated to clinics. The present study demonstrates the role of the waveform in electrical signal to direct differentiation of stem cells on an electroactive polymeric substrate, using monophasic DC, square wave, and biphasic wave. In this regard, an in-house electrical stimulation device has been fabricated for the uninterrupted delivery of programmed electrical signals to stem cells in culture. To provide a functional platform for stem cells to differentiate, barium titanate (BaTiO₃ , BT) reinforced PVDF has been developed with mechanical properties similar to bone. The electrical stimulation of human mesenchymal stem cells (hMSCs) on PVDF/BT composite inhibited proliferation rate at day 7, indicating early commitment for differentiation. The phenotypical characteristics of DC stimulated hMSCs provided signatures of differentiation towards osteogenic lineage, which was subsequently confirmed using ALP assay, collagen deposition, matrix mineralization, and genetic expression. Our findings suggest that DC stimulation induced early osteogenesis in hMSCs with a higher level of intracellular reactive oxygen species (ROS), whereas the stimulation with square wave directed late osteogenesis with a lower ROS regeneration. In summary, the present study critically analyzes the role of electrical stimulation and its waveforms in regulating osteogenesis, without external biochemical differentiation inducers, on a bone-mimicking functional substrate. Such a strategy can potentially be adopted to develop orthopedic implant-based bioelectronic medicine for bone regeneration. This article is protected by copyright. All rights reserved.

Myeloid mineralocorticoid receptors contribute to skeletal muscle repair in muscular dystrophy and acute muscle injury

Suppressing mineralocorticoid receptor (MR) activity with MR antagonists is therapeutic for chronic skeletal muscle pathology in Duchenne muscular dystrophy (DMD) mouse models. Although mechanisms underlying clinical MR antagonist efficacy for DMD cardiomyopathy and other cardiac diseases are defined, mechanisms in skeletal muscles are not fully elucidated. Myofiber MR knockout improves skeletal muscle force and a subset of dystrophic pathology. However, MR signaling in myeloid cells is known to be a major contributor to cardiac efficacy. To define contributions of myeloid MR in skeletal muscle function and disease, we performed parallel assessments of muscle pathology, cytokine levels, and myeloid cell populations resulting from myeloid MR genetic knockout in muscular dystrophy and acute muscle injury. Myeloid MR knockout led to lower levels of C-C motif chemokine receptor 2 (CCR2)-expressing macrophages, resulting in sustained myofiber damage after acute injury of normal muscle. In acute injury, myeloid MR knockout also led to increased local muscle levels of the enzyme that produces the endogenous MR agonist aldosterone, further supporting important contributions of MR signaling in normal muscle repair. In muscular dystrophy, myeloid MR knockout altered cytokine levels differentially between quadriceps and diaphragm muscles, which contain different myeloid populations. Myeloid MR knockout led to higher levels of fibrosis in dystrophic diaphragm. These results support important contributions of myeloid MR signaling to skeletal muscle repair in acute and chronic injuries and highlight the useful information gained from cell-specific genetic knockouts to delineate mechanisms of pharmacological efficacy.

Silane-treated BaTiO3 ceramic powders for multilayer ceramic capacitor with enhanced dielectric properties

Silane/ceramic combination provides the composites with several advantages from the advancements of new ceramic composite materials with good thermal conductivity, high mechanical and dielectric properties have wide significant applications in electrical and electronic industries. In this study, to enhance the dispersibility of dielectric barium titanate (BaTiO₃) ceramic powder and additives for the fabrication of multilayer ceramic capacitors (MLCCs), surface treatment of the precursor of ceramic powder was performed using silane coupling agents. Dielectric ceramic sheets fabricated from ceramic powders that had been surface-treated with different amounts of N-[3-(trimethoxysilyl)propyl]aniline (TMSPA) which increased the surface gloss. In particular, the dielectric properties of the multilayer ceramic sheet fabricated by stacking sheets from the TMSPA-treated ceramic powder sintering at 1200 °C, it was confirmed that the dielectric constant increased from 881 to 2382 and the dielectric loss dropped from 1.96 to 1.34% with utilization of the TMSPA treatment. The physical and dielectric properties of the TMSPA-treated multilayer ceramic sheet were also determined by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, glossmetry, and electrochemical impedance analysis. The results revealed that the TMSPA-modified BaTiO₃ surfaces considerably increased the dielectric property of the fabricated nanocomposite.

Effects of particle size and polymorph type of TiO2 on the properties of BaTiO3 nanopowder prepared by solid-state reaction

Barium titanate (BaTiO₃) has attracted considerable attention as a perovskite ferroelectric ceramic material for electronic multilayer ceramic capacitors (MLCCs). Fine BaTiO₃ nanopowders with a considerably high tetragonality directly influence the typical properties of nanopowders; however, their synthesis has remained challenging. In this study, we analyzed the effect of two different TiO₂ powders with anatase and rutile phases in a solid-state reaction with barium carbonate (BaCO₃). The effect of the particle size ratio (TiO₂/BaCO₃) of the raw materials on the tetragonality and particle size of the as-synthesized BaTiO₃ powders was also determined through extensive characterization of the powders by X-ray diffraction, field-emission scanning electron microscopy, and Raman spectroscopy. The present investigation reveals that the design BaTiO₃ structure is expected to advance the development of efficient catalytic and sensor materials for sustainable environmental applications.

In-situ thermal phase transition and structural investigation of ferroelectric tetragonal barium titanate nanopowders with pseudo-cubic phase

Optimization and miniaturization of existing electronic devices require the development of advanced nanostructured materials with high phase and structural purity. Over the past decade, barium titanate (BaTiO₃) has attracted considerable attention due to its outstanding ferroelectric and dielectric properties. The present study involved the investigation of the phase transition and structural stability of tetragonal BaTiO₃ nanopowders with pseudo-cubic phase using an in-situ high resolution and high temperature X-ray diffraction method. Under ambient conditions, the coexistence the tetragonal and cubic phases with weight fractions of 75.7% and 24.3%, respectively, was determined in BaTiO₃. In the temperature range of 25 °C-300 °C, phase boundaries of BaTiO₃ (180 nm in size) exhibiting several phases were detected. The phase transformation behavior, relative crystal phase content, lattice parameters, crystallite size, and tetragonality of the BaTiO₃ nanopowders were established by the Rietveld refinement method at the onset temperature from 25 °C to 300 °C. Up to 150 °C, the nanopowders exhibited a complete transition of the cubic phase. Additionally, a complete tetragonal to cubic transformation was accomplished by a decrease of tetragonality at 125 °C and an increase in the crystallite size at 300 °C.

A critical review on strategies for improving efficiency of BaTiO3-based photocatalysts for wastewater treatment

Barium titanate (BaTiO₃) photocatalysts with perovskite structures are promising candidates for the effective removal of hazardous organic pollutants from water/wastewater owing to several advantages, including low cost, non-toxicity, high stability, environmental friendliness, favorable band positions, high oxygen vacancies, multiple crystal phases, rapid migration of charge carriers at the surface, band bending, spontaneous polarization, and easy tailoring of the sizes and morphologies. However, this high dielectric/ferroelectric material is only active in UV light (band gap: 3.2 eV), which reduces the photocatalytic degradation performance. To make barium titanate more suitable for photocatalysis, the surfaces of the powders can be modified to broaden the absorption band. In this paper, various strategies for improving photocatalysis of barium titanate for removing organic pollutants (mostly dyes and drugs) from water/wastewater are critically reviewed. They include modifying the sizes and morphologies of the particles by varying the reaction times and synthesis temperatures, doping with metals/non-metals, loading with noble metal NPs (Ag and Au), and fabrication of heterojunction photocatalysts (conventional type II and Z-scheme). The current challenges and possible future directions of BaTiO₃-based materials are also discussed. This comprehensive review is expected to advance the design of highly efficient BaTiO₃-based materials for photocatalytic applications in water/wastewater treatment.

Multiple rapid swallows and rapid drink challenge in patients with esophagogastric junction outflow obstruction on high-resolution manometry

BACKGROUND

Esophagogastric junction outflow obstruction (EGJOO) as defined by Chicago Classification of esophageal motility disorders (CCv3.0) encompasses a broad range of diagnoses, thus posing clinical challenges. Our aims were to evaluate multiple rapid swallow (MRS) and rapid drink challenge (RDC) during high-resolution manometry (HRM) to aid identifying clinically relevant EGJOO.

METHODS

Patients with a HRM diagnosis of EGJOO based on CCv3.0 that also completed MRS and RDC during HRM and barium esophagram were retrospectively identified. Radiographic EGJOO (RAD-EGJOO) was defined by either liquid barium retention or delayed passage of a barium tablet on barium esophagram. Thirty healthy asymptomatic controls that completed HRM were also included. MRS involved drinking 2 mL for 5 successive swallows. RDC involved rapid drinking of 200 mL liquid. Integrated relaxation pressure (IRP) and presence of panesophageal pressurization (PEP) during MRS and RDC were assessed.

KEY RESULTS

One hundred one patients, mean (SD) age 56 (16) years, were included; 32% had RAD-EGJOO, 68% did not. RAD-EGJOO patients more frequently had elevated (>12 mmHg) upright IRP (100%), MRS-IRP (56%), RDC-IRP (53%), and PEP during RDC (66%) than both controls [17%; 0%; 7%; 3%] and patients without RAD-EGJOO [83%; 35%; 39%; 41%] Having IRP >12 mmHg during both MRS and RDC was twice as likely to be associated with RAD-EGJOO (19%) than those without RAD-EGJOO (9%) among patients with upright IRP >12 mmHg.

CONCLUSIONS AND INFERENCES

Adjunctive HRM maneuvers MRS and RDC appear to help identify clinically significant EGJOO. While future outcome studies are needed, comprehensive multimodal evaluation helps clarify relevance of EGJOO on HRM.

Field-controlled magnetoelectric core-shell CoFe2O4@BaTiO3 nanoparticles as effective drug carriers and drug release in vitro

The targeted drug release at tumor cells while sparing normal cells is a huge challenge. Core-shell magnetoelectric (ME) nanoparticles have addressed this problem using shape-dependent magneto-electric attributes. The colloidally stable, core-shell cobalt ferrite@barium titanate (CFO@BTO) ME nanoparticles (NPs) used for in vitro study were synthesized using sonochemical method. The structural characteristics and core-shell morphology were analyzed by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) respectively. Further magnetic and exchange coupling between two phases of ME nanostructures were studied at room temperature. Colloidal stability was studied in different suspension solutions (Water, SBB, PBS, and DMEM) using dynamic light scattering. Subsequently, the synthesized nanoparticles were functionalized with anticancer drugs including doxorubicin and methotrexate up to 80% via (EDC) chemistry. In vitro cytotoxicity studies carried out on human hepatocellular carcinoma (HepG2) and human malignant melanoma (HT144), cells validated the magneto-electric property of CFO@BTO nano-carriers in the presence of external magnetic field (5 mT), with significantly enhanced cytotoxicity when compared to free drugs and without field replicates. The resulted IC₅₀ values ranging from 5.3-7.3 μg/ml compared to 30.1-43.1 μg/ml in the absence of a magnetic field also confirmed the involved physical attributes of magnetoelectric nanostructures. The fluorescent microscopy results also indicated the increased apoptosis in magnetic field-assisted samples. Finally, hemolysis assay indicated the suitability of CFO@BTO nano-carriers for intravenous applications at IC₅₀ concentration.

Metasurface Resonator for 1.5 T MRI Based on BaTiO3 Host Material

Magnetic resonance imaging (MRI) is a widely used clinical tool for medical diagnosis and therapy. Several research studies focus on passively improving MRI sensitivity using high dielectric constant (HDC) materials and metamaterials. In this work, we investigate a new metasurface resonator which can enhance local transmit and receive efficiency in 1.5T MRI. The metasurface has been realized with an array of non-magnetic rods embedded in two blocks of a BaTiO₃ aqueous mixture. BaTiO₃ when mixed with water exhibits high dielectric permittivity values in the 40-200 MHz range, allowing the design of a compact and safe device for practical use in an MRI scanner. Simulation results show 50% enhancement of the magnetic field in the region-of-interest. The resonance frequency of the metasurface is also validated experimentally with a small loop antenna and a vector network analyzer (VNA) in a laboratory-controlled environment.

A novel nanobiosorbent of functionalized graphene quantum dots from rice husk with barium hydroxide for microwave enhanced removal of lead (II) and lanthanum (III)

In this study, rice husk was used as a sustainable source to synthesize graphene quantum dots (GQDOs) with 2D morphology. Chemical modification of GQDOs with Ba(OH)₂ was followed to form a novel GQDOs-Ba nanobiosorbent with an increased number of surface hydroxyl groups. The physicochemical properties of GQDOs and GQDOs-Ba were investigated by FT-IR, SEM, TEM, TGA, and XRD. The adsorption parameters of Pb(II) and La(III) onto GQDOs-Ba were optimized using microwave sorption approach. The maximum capacity reached 3400 µmol g^-1 (pH 7), and 1500 µmol g^-1 (pH 5) at 15 s for Pb(II) and La(III), respectively. The adsorption isotherm models by GQDOs-Ba fitted well with Langmuir. The pseudo-second order was agreed by Pb(II) and La(III) ions. The thermodynamic studies elucidated that Pb(II) and La(III) adsorption onto GQDOs-Ba followed a spontaneous model. The GQDOs-Ba nanobiosorbent accomplished excellent removal percentages from different water samples containing lead (98.5%-99.8%) and lanthanum (94.6%-96.2%).

Artificial Asymmetric Cilia Array of Dielectric Elastomer for Cargo Transportation

Inspired by natural ciliary movement, artificial cilia systems have recently been developed to transport microparticles and target biomolecules by the external stimuli-induced bend and twist. However, the directional transportation of cargo meets a major challenge. Here, we present an artificial asymmetric cilia array of dielectric elastomer and realize the cargo directional transportation under alternating-current (ac) electric field. Such a dielectric elastomer is composed of elastomer matrix and dielectric barium titanate (BaTiO₃) nanoparticles, which can be polarized under an ac electric field and results in the swinging of artificial elastomer cilia. The asymmetry of the cilia endows themselves with the capability of asymmetric recovery stroke, which is essential for directional transportation of cargo. Transporting performance is also optimized by adjusting the applied frequencies and voltages. This study may provide a new clue to construct functional "smart" devices in electromechanical systems and biomedicine.

Removal of high concentration of sulfate from pigment industry effluent by chemical precipitation using barium chloride: RSM and ANN modeling approach

Sulfate ions pose a major threat and challenge in the treatment of industrial effluents. The sample of wastewater obtained from a pigment industry contained large quantities of sulfate in the form of sodium sulfate which resulted in high TDS. As the removal of sulfate from pigment industry effluent was not reported previously, this work was focused on removing the sulfate ions from the effluent by chemical precipitation using barium chloride. The efficiency of sulfate removal was nearly 100% at an excess dosage of barium chloride, which precipitates the dissolved sulfate ions in the form of barium sulfate. Optimization of the parameters was done using Response Surface Methodology (RSM). This work is the first attempt for modeling the removal of sulfate from pigment industry effluent using RSM and Artificial Neural Network (ANN). Prediction by both the models was evaluated and both of them exhibited good performance (R² value > 0.99). It was observed that the prediction by RSM (R² value 0.9986) was closer to the experimental results than ANN prediction (R² value 0.9955). The influence on the pH and conductivity of the solution by dosage of precipitant was also studied. The formation of barium sulfate was confirmed by characterization of the precipitate. Therefore, the sulfate removed from the effluent was converted into a commercially valuable precipitate.

Potential of Osteoblastic Cells Derived from Bone Marrow and Adipose Tissue Associated with a Polymer/Ceramic Composite to Repair Bone Tissue

One of the tissue engineering strategies to promote bone regeneration is the association of cells and biomaterials. In this context, the aim of this study was to evaluate if cell source, either from bone marrow or adipose tissue, affects bone repair induced by osteoblastic cells associated with a membrane of poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT). Mesenchymal stem cells (MSC) were isolated from rat bone marrow and adipose tissue and characterized by detection of several surface markers. Also, both cell populations were cultured under osteogenic conditions and it was observed that MSC from bone marrow were more osteogenic than MSC from adipose tissue. The bone repair was evaluated in rat calvarial defects implanted with PVDF-TrFE/BT membrane and locally injected with (1) osteoblastic cells differentiated from MSC from bone marrow, (2) osteoblastic cells differentiated from MSC from adipose tissue or (3) phosphate-buffered saline. Luciferase-expressing osteoblastic cells derived from bone marrow and adipose tissue were detected in bone defects after cell injection during 25 days without difference in luciferin signal between cells from both sources. Corroborating the in vitro findings, osteoblastic cells from bone marrow combined with the PVDF-TrFE/BT membrane increased the bone formation, whereas osteoblastic cells from adipose tissue did not enhance the bone repair induced by the membrane itself. Based on these findings, it is possible to conclude that, by combining a membrane with cells in this rat model, cell source matters and that bone marrow could be a more suitable source of cells for therapies to engineer bone.

[Effects of saliva contamination on bond strength of resin-resin interfaces]

OBJECTIVE

To estimate the bond strength between different resin composite interfaces, and to evaluate the effect of saliva contamination and management with the contamination on the bond strength.

METHODS

Two commercial resin composites containing different types of fillers (AP-X: barium-glass; P60: quartz) were tested in this study. The basic composite blocks were made of AP-X. After wet-ground flatted, the experimental groups were divided into three groups according to the surface treatment: (1)Direct bonding group: the bonding surface was rinsed with distilled water for 20 s, then dried with oil-free air for 20 s; (2)Saliva contamination group: the bonding surface was bathed in saliva for 30 min, then distilled water was rinsed for 20 s and dried with oil-free air for 20 s; (3)Saliva contamination and 75% ethanol wiping group: bonding surface bathed in saliva for 30 min, then wipe the surface with 75% ethanol, distilled water rinse for 20 s and dry with oil-free air for 20 s; The control group was made of the basic composite bulks of AP-X directly bonding with composite P60. Cut each resin block into 1 mm×1 mm×14 mm sticks, observing the micro-structures and detecting the micro-tensile strength of the resin composite interfaces. The bonding strength was measured using micro-tensile tester, then calculated and statistically analyzed by one-way ANOVA.

RESULTS

Scanning electronic microscope observation revealed that the control group as well as the direct bonding subgroups, two different resin tags were in good contact with each other. The saliva contamination subgroups had lots of gaps or craters, indicating saliva might have been trapped in the composite buildup and wiping the surface with 75% ethanol had no effect. The micro-tensile bond strength of the control group was (84.07±1.57) MPa and significantly higher than all the other 3 experimental subgroups(P<0.001). In experimental groups, the micro-tensile strength of 3 subgroups was (76.08±2.42) MPa, (70.98±2.33) MPa and (71.08±2.33) MPa, respectively. The saliva contamination subgroup was significant lower than the direct bonding subgroup(P<0.001), but no statistical significance with the ethanol wiping subgroup(P=0.893).

CONCLUSION

The bond strength of inner polymerization of resin-resin was greater, but decreased after resin composites interfacial bonding. Saliva contamination reduced the tensile bond strength between resin composites surface, wiping the surface with 75% ethanol had no effect.

Non-invasive Pregnancy Diagnosis from Urine by the Cuboni Reaction and the Barium Chloride Test in Donkeys (Equus asinus) and Alpacas (Vicugna pacos)

The aim of the research was to evaluate two chemical tests for non-invasive pregnancy diagnosis from urine, the Cuboni reaction and the barium chloride test, in donkeys (Equus asinus) and alpacas (Vicugna pacos). The research was carried out from April 2013 to September 2014. Urine samples were collected on five private Czech farms from 18 jennies and 12 alpaca females. Urine was collected non-invasively into plastic cups fastened on a telescopic rod, at 6-9 week intervals. In total, 60 and 54 urine samples from alpacas and jennies, respectively, were collected. The Cuboni reaction was performed by the State Veterinary Institute Prague. The barium chloride test was done with 5 ml of urine mixed together with 5 ml of 1% barium chloride solution. Results of the Cuboni reaction were strongly influenced by the reproductive status of jennies; the test was 100% successful throughout the second half of pregnancy. However, no relationship was found between the real reproductive status of alpaca females and results of the Cuboni reaction. It was concluded that the barium chloride test is not suitable for pregnancy diagnosis either in donkeys, due to significant influence of season on the results, or in alpacas, because no relationship between results of the test and the reproductive status of alpaca females was found. In conclusion, the Cuboni reaction has potential to become a standard pregnancy diagnostic method in donkeys.

Identification of Novel Short BaTiO3-Binding/Nucleating Peptides for Phage-Templated in Situ Synthesis of BaTiO3 Polycrystalline Nanowires at Room Temperature

Ferroelectric materials, such as tetragonal barium titanate (BaTiO3), have been widely used in a variety of areas including bioimaging, biosensing, and high power switching devices. However, conventional methods for the synthesis of tetragonal phase BaTiO3 usually require toxic organic reagents and high temperature treatments, and are thus not environment-friendly and energy-efficient. Here, we took advantage of the phage display technique to develop a novel strategy for the synthesis of BaTiO3 nanowires. We identified a short BaTiO3-binding/nucleating peptide, CRGATPMSC (named RS), from a phage-displayed random peptide library by biopanning technique and then genetically fused the peptide to the major coat protein (pVIII) of filamentous M13 phages to form the pVIII-RS phages. We found that the resultant phages could not only bind with the presynthesized BaTiO3 crystals but also induce the nucleation of uniform tetragonal BaTiO3 nanocrystals at room temperature and without the use of toxic reagents to form one-dimensional polycrystalline BaTiO3 nanowires. This approach enables the green synthesis of BaTiO3 polycrystalline nanowires with potential applications in bioimaging and biosensing fields.

Single-cell screening and quantification of transcripts in cancer tissues by second-harmonic generation microscopy

Fluorescence-based single molecule techniques to interrogate gene expression in tissues present a very low signal-to-noise ratio due to the strong autofluorescence and other background signals from tissue sections. This report presents a background-free method using second-harmonic generation (SHG) nanocrystals as probes to quantify the messenger RNA (mRNA) of human epidermal growth receptor 2 (Her2) at single molecule resolution in specific phenotypes at single-cell resolution directly in tissues. Coherent SHG emission from individual barium titanium oxide (BTO) nanoprobes was demonstrated, allowing for a stable signal beyond the autofluorescence window. Her2 surface marker and Her2 mRNA were specifically labeled with BTO probes, and Her2 mRNA was quantified at single copy sensitivity in Her2 expressing phenotypes directly in cancer tissues. Our approach provides the first proof of concept of a cross-platform strategy to probe tissues at single-cell resolution in situ.

A novel method to decrease electric field and SAR using an external high dielectric sleeve at 3 T head MRI: numerical and experimental results

Materials with high dielectric constant (HDC) have been used in high field MRI to decrease specific absorption rate (SAR), increase magnetic field intensity, and increase signal-to-noise ratio. In previous studies, the HDC materials were placed inside the RF coil decreasing the space available. This study describes an alternative approach that considers an HDC-based sleeve placed outside the RF coil. The effects of an HDC on the electromagnetic (EM) field were studied using numerical simulations with a coil unloaded and loaded with a human head model. In addition, experimental EM measurements at 128 MHz were performed inside a custom-made head coil, fitted with a distilled water sleeve. The numerical simulations showed up to 40% decrease in maximum 10 g-avg. SAR on the surface of the head model with an HDC material of barium titanate. Experimental measurements also showed up to 20% decrease of maximum electric field using an HDC material of distilled water. The proposed method can be incorporated in the design of high field transmit RF coils.

Surface roughness of etched composite resin in light of composite repair

OBJECTIVES

In search for clinically effective composite repair protocols, the effect of various etching protocols on the surface roughness of composite resins with different filler composition were investigated.

METHODS

Of two composite resins (hybrid-filled Clearfil AP-X; nano-filled Filtek Supreme XT) specimens of 3mm thick with a diameter of 7 mm were prepared (n=24). The top surface was polished with 4000-grit SiC-abrasive paper and subjected to one of eight surface treatments: (n=3): negative control (NC), 37% phosphoric acid for 20s (37PA-20s), 3% hydrofluoric acid for 20s (3HF-20s), for 120 s (3HF-120 s), 9.6% hydrofluoric acid for 20s (9.6HF-20s), for 120 s (9.6%HF-120 s), 37PA-20s followed by 9.6%HF for 120 s (37PA-20s/9.6HF-120 s) and 9.6%HF for 120 s followed by 37PA-20s (9.6HF-120s/37PA-20s). Roughness (S(a)) was measured using a 3D noncontact optical interferometer (WYKO) and surface topography imaged by SEM. Multilevel models were used to estimate the variances within a sample and between samples in each group. Using the resulting overall variances and the means for each group, the eight groups were compared consecutively using t-tests (p<0.05).

RESULTS

The hybrid-filled composite resin demonstrated a significantly rougher surface than the nano-filled (p<0.05). For both composites 9.6%HF-120 s, 37PA-20s/9.6HF-120 s and 9.6%HF-120 s/37PA-20s resulted in a large increase in roughness compared to the other groups (p<0.05). For the hybrid-filled, the succeeding groups (37PA-20s, 3HF-20s, 3HF-120 s and 9.6HF-20s) resulted in a statistically significant increase in surface roughness (p<0.02). For the nano-filled only a statistically significant increase in roughness was found between 3HF-20s and 3HF-120 s (p<0.001) and between 9.6HF-20s and 9.6HF-120 s (p<0.001). SEM surface characterization revealed that the hybrid-filled composite resin was much more affected by etching than the nano-filled.

SIGNIFICANCE

Composite resins should not be seen as a group of materials having identical properties when it comes to repair. The effect of etching will depend on the composition of the filler particles.

Load-bearing capacity of handmade and computer-aided design--computer-aided manufacturing-fabricated three-unit fixed dental prostheses of particulate filler composite

OBJECTIVE

To compare handmade and computer-aided design-computer-aided manufacturing (CAD-CAM)-fabricated fixed dental prostheses (FDPs) composed of a particulate filler composite.

MATERIAL AND METHODS

Handmade FDPs were made of restorative composite (Z 100) and CAD-CAM-fabricated FDPs were made of commercial CAD-CAM blocks (VITA Temp) and two experimental CAD-CAM blocks of particulate filler composite. Experimental CAD composite A was prepared by mixing 31.2 wt.% of dimethacrylate resin with 68.7 wt.% of filler particles of barium oxide silicate (BaSiO(2)). Experimental CAD composite B was prepared by mixing 25.6 wt.% of dimethacrylate resin with 74.3 wt.% of filler particles of BaSiO(2). Six groups were fabricated (n = 6 in each); FDPs were statically loaded until final fracture.

RESULTS

Experimental CAD composites A and B revealed the highest load-bearing capacity of the FDPs, while Z 100 showed the lowest.

CONCLUSION

FDPs made of experimental CAD composite blocks showed higher load-bearing capacities than handmade commercial composites and commercial blocks.

Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L)

This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters.

A comparison of panoramic image quality between a digital radiography storage phosphor system and a film-based system

AIM

To compare digital panoramic images acquired for the presurgical assessment of third molars captured with a storage phosphor-based system with conventional film panoramic radiographs.

METHODS AND MATERIALS

A total of 51 pairs of digital and conventional panoramic images, made simultaneously, were included in this study. The images were evaluated for diagnostic quality prior to third molar surgery by two experienced oral surgeons and rated with a four-point grading scale.

RESULTS

Despite the fact that conventional panoramic images were rated higher than the digital images, the difference was not statistically significant.

CONCLUSIONS

Conventional and digital panoramic images were found to be of comparable image quality with regard to their diagnostic contribution to third molar surgery.

CLINICAL SIGNIFICANCE

This study is contributory to understanding differences in image quality between digital and conventional panoramic radiography for certain diagnostic tasks. The lack of significant differences in image quality may be an endorsement for digital panoramic radiography.

Layered silver nanoparticles embedded in a BaF(2) matrix: optical characterization

Multilayer stacks of silver and BaF(2) alternate layers have been deposited by thermal evaporation on a silica substrate with the aim to obtain Ag clusters dispersed in a BaF(2) insulator matrix. The Ag layer thickness was approximately 1.2 nm; the thickness of the BaF(2) layer was approximately 25 nm. The samples were thermally treated for a 1 h thermal annealing process at 500 degrees C. These kinds of multilayer device also have several applications in the field of optics for the realization of antireflection coatings. However, optical characterization of dielectric matrices that contain layered metallic nanoparticles still remains an unsolved problem in the field of nanostructured optical coatings. Therefore, the surface plasmon resonance peak that appears in the optical absorption spectra because of the formation of Ag nanoclusters inside the BaF(2) insulator matrix has been monitored and fitted by numerical codes. In particular, a previously published theoretical model, based on the Maxwell-Garnett effective medium theory, modified to take into account the effects that are due to the particle shapes and the spatial arrangement of the clusters, has been employed to fit the optical absorption spectra.

[Effect of Ning Wei Kang Recipe extract on gastrointestinal motor function]

OBJECTIVE

To study the effect of Ning Wei Kang Recipe extract on gastrointestinal motor function.

METHODS

The effects of Ning Wei Kang Recipe extract on gastrointestinal motor function were studied in mice, rabbits, and isolated mesenterial intestines of guinea pig according to its effect on acetylcholine or barium chloride-induced contraction.

RESULTS

Ning Wei Kang Recipe extract could significantly decrease the propellent movement of medicine charcoal in the mesenterial intestine of mice (P < 0.01), inhibit the range and speed of mesenterial intestine of rabbits (P < 0.05, or P < 0.01), relax the contration of isolated mesenterial intestines of guinea pig induced by BaCl2 (P < 0.05). But it could not decrease the contration of isolated mesenterial intestines of guinea pig induced by acetylcholine (P< 0.05).

CONCLUSIONS

Ning Wei Kang Recipe extract can significantly inhibit the gastrointestinal motor function. It may be related to blocking positive ion-Ba2+ into gastrointestinal smooth muscle cell.

New insights into the structural characteristics of the arabinogalactan-protein (AGP) fraction of gum arabic

The structural characteristics of the gum exudate of Acacia senegal (gum arabic) have been investigated by monitoring the composition and physicochemical properties before and after treatment with proteolytic enzyme and various alkaline systems. Molecular mass ( M w) and radius of gyration ( R g) measurements were performed using gel permeation chromatography (GPC) coupled to refractive index, UV absorbance, and multiangle light scattering detectors and indicated that the macromolecules present have a compact structure. It was found that treatment with proteolytic enzyme caused the arabinogalactan-protein component (AGP) with average molecular mass approximately 2 x 10 (6) Da to degrade, yielding material of molecular mass approximately 4 x 10 (5) Da, whereas the bulk of the material corresponding to the protein-deficient arabinogalactan component (AG) with molecular mass 4 x 10 (5) remained unaffected. Barium hydroxide was found to hydrolyze the polysaccharide component (AG) itself in addition to the proteinaceous component as demonstrated in control experiments using dextran. However, sodium borohydride/sodium hydroxide treatments were unable to hydrolyze dextran and were assumed to hydrolyze only the proteinaceous component of gum arabic. The AGP component was completely degraded, yielding material of molecular mass approximately 4.5 x 10 (4) Da. It has been concluded, therefore, that the enzyme did not fully hydrolyze all of the protein present and that the AGP component of gum arabic consists of carbohydrate blocks of approximately 4.5 x 10 (4) Da linked to a polypeptide chain consistent with the wattle blossom structure. Because the AGP was degraded to differing extents using a mild and more severe sodium borohydride/sodium hydroxide treatment, it was concluded that the polysaccharide moieties were linked through both O-serine and O-hydroxyproline residues. The gum arabic sample was deglycosylated by treatment with anhydrous hydrogen fluoride and revealed the presence of two putative core proteins of approximately 3 x 10 (4) and approximately 5 x 10 (3) Da, respectively, which correspond to proteins of approximately 250 and 45 amino acids in length. A new model for the structure of the AGP component has been proposed.

[Research of changes in the mechanical properties and curability of composite core materials modified with ultrafine diamond]

OBJECTIVE

As a new kind of reinforcing filler, ultrafine diamond (UFD) is added into photocurable composite core materials. The properties of the materials are then measured to see if there is any improvement.

METHODS

Different content of barium glass and UFD were added into resin matrix to fabricate six groups of photocurable composite core materials. For each group of the materials, the flexural strength, Vicker's micro-hardness and depth of cure were measured. Data of the flexural strength and Vicker's micro-hardness was then collected and analyzed by One-Way ANOVA.

RESULTS

For the two kinds of composites with barium glass of 60% and 70%, only a small quantity of modified UFD with 0.2% weight percentage could improve the flexural strength of the composites by 34% and 21% respectively, the microhardness was improved by 23% and 30% respectively. The depth of cure of the composite core materials were more than 2 mm, which had reached the demand of the corresponding ISO criteria. The addition of UFD could make the composite core materials darker and grayer.

CONCLUSION

Micro-quantity of UFD can improve the mechanical properties of composite resins notably, and it will not affect the curability of the materials, but the defect in the color need to be reformed.

Current and future clinical strategies in colon cancer prevention and the emerging role of chemoprevention

In the third millennium preventive medicine is becoming a corner stone in our concept of health. Colorectal cancer (CRC) fits the criteria of a disease suitable for prevention interventions. It is a prevalent disease that is associated with considerable mortality and morbidity rates, with more than 1,000,000 new cases and 500,000 deaths annually. CRC has a natural history of transition from precursor to malignant lesion that spans, on average, 10-15 years, providing a window of opportunity for effective interventions and prevention. Indeed, CRC is preventable in up to 90% of the cases. Simple life style modifications (balanced diet avoidance of smoking and alcohol, and moderate physical activity) can prevent up to 50% of the cases of colorectal cancer. Compliance with current screening methods is a major barrier to the achievement of optimal results, a large part of the average risk population has not been screened by any method. Several newly developed screening modalities, such as the virtual colonoscopy and stool genetic testing may improve compliance. In addition, chemoprevention, a new science that has emerged during the last decade, presents an alternative approach to reducing mortality from colorectal cancer as well as other cancers. Chemoprevention involves the long-term use of a variety of oral agents that can delay, prevent or even reverse the development of adenomas in the large bowel. In light of the recent evidence of the efficacy of chemoprevention in persons at high risk for CRC cancer, it seems only appropriate to consider similar strategies for the general population.

Congenital bronchoesophageal fistula in an adult: A case report

Bronchoesophageal fistulas are usually diagnosed in the neonatal period. As such, the condition is rare in adults. We present a case of a congenital bronchoesophageal fistula in a 62-year-old man with the complaint of severe bouts of cough and choking after swallowing liquid. His workup included a barium esophagogram that revealed a fistula between the esophagus and a right lower lobe bronchus. The diagnosis should be considered in certain individuals with suggestive symptomatology and unexplained respiratory pathology. The fistula was divided and resected, The patient had an uneventful recovery.

Local Replenishment of Coral Reef Fish Populations in a Marine Reserve

The scale of larval dispersal of marine organisms is important for the design of networks of marine protected areas. We examined the fate of coral reef fish larvae produced at a small island reserve, using a mass-marking method based on maternal transmission of stable isotopes to offspring. Approximately 60% of settled juveniles were spawned at the island, for species with both short (<2 weeks) and long (>1 month) pelagic larval durations. If natal homing of larvae is a common life-history strategy, the appropriate spatial scales for the management and conservation of coral reefs are likely to be much smaller than previously assumed.

Large Hiatal Hernia with Floppy Fundus: Clinical and Radiographic Findings

OBJECTIVE

The purpose of this study was to compare the clinical and barium radiographic findings for 17 patients with large hiatal hernias and a floppy fundus with those for 61 patients with large hiatal hernias but no floppy fundus.

CONCLUSIONS

Patients with large hiatal hernias can develop a floppy fundus, which has a characteristic appearance on barium studies because it droops below the most superior portion of the herniated gastric body. Distortion of the gastric anatomy in patients with this type of hernia can cause mechanical symptoms that usually resolve after surgical repair of the hernia. Radiologists should be aware of the barium radiographic findings associated with a floppy fundus and of the potential role of surgery in the treatment of patients with symptoms.

Characterization of fine grain Ba0.995Y0.005TiO3 ceramics obtained from gel-precursor nanopowder

Using an acetate-alkoxide sol-gel route in which the precursors are barium acetate, yttrium isopropoxide and titanium diisopropoxide bis-acetylacetonate, we prepared a ferroelectric material with the formula: Ba1-xYxTiO3, x = 0.005. SEM analysis showed a polymeric microstructure of the gel due to the chelated titanium alkoxide precursor used as starting materials. The evolution of the structure and microstructure of the precursor gel heated at temperatures up to 1000 degrees C was studied by various techniques. The powder obtained by heating the gel at 1100 degrees C presented a homogeneous structure consisting of submicronic particles (approximately 200 nm). XRD and SAED analyses revealed that Ba0.995Y0.005TiO3 nanocrystals of about 5-10 nm appeared at 600 degrees C, together with BaCO3. The presence of barium carbonate was identified also by IR spectroscopy and thermal analyses. The ceramics obtained from the as-prepared powder presented good dielectric properties (capacitance = 840 pF/dielectric constant = 3860 and dielectric loss (tandelta) = 0.078 at Curie temperatures of 120-121 degrees C).

Effect of Filler Properties in Composite Resins on Light Transmittance Characteristics and Color

The purpose of this investigation was to examine the effect of filler particle size and shape as well as filler content on light transmittance characteristics and color of experimental composite resins. A mixture of 30 mol% Bis-GMA and 70 mol% TEGDMA was prepared as a base monomer and to which a photoinitiator (camphorquinone) and a co-initiator (N,N-dimethylaminoethyl methacrylate) were added. Four different irregular- and spherical-shaped filler types with an average particle size of 1.9-11.1 microm were added to the mixture in three different filler contents of 20, 30, and 40 vol%. Light transmittance characteristics including light diffusion characteristics of the materials were evaluated. Color values and color differences among filler contents of the materials were also determined. Materials containing smaller and irregular-shaped fillers showed higher light transmittance and diffusion angle distribution with a sharper peak, as compared with those containing larger and spherical-shape fillers. It was also found that there was a significant correlation between the specific surface area of fillers and the color difference of the materials containing the fillers. Our results indicated that the shape of filler particles, as well as particle size and filler content, significantly affected the light transmittance characteristics--including light diffusion characteristics--and color of composite resins.

The effect of nanofiller on the opacity of experimental composites

The purpose of this study was to evaluate the effect of the nanofiller in experimental composites on opacity (contrast ratio). Thirteen experimental composites were prepared with three different sizes of fillers: barium glass minifiller (1 microm; 69-76 wt %), silica microfiller (0.04 microm; 0-6 wt %), and silica nanofiller (7 nm; 0-7 wt %). After disk-type specimens were irradiated with a halogen light curing unit at 500 mW/cm(2) for 30 s, the specimens were aged for 6 h at room conditions and were stored in deionized water for 1, 7, 14, 21, 28, 56, and 84 days. The contrast ratios of the specimens were measured as a function of aging period using a spectrophotometer. The distribution morphology of the filler particles in the resin matrix was also examined using energy-filtering transmission electron microscopy. The experimental composites that contained more than 3% nanofiller had significantly lower contrast ratios (p < 0.05). The composites that contained 6 wt % nanofiller had contrast ratios 34-65% lower than the composite that did not contain nanofiller. The values of the contrast ratio from the composites that excluded microfiller were lower than the values from the composites that included microfiller. From the comparison with the 3 different sizes of filler, the contrast ratio of the composite that contained 70 wt % minifiller and 6 wt % microfiller was the highest, the contrast ratio of the composite that contained only 76 wt % minifiller was the median value, and the contrast ratio of the composite that contained 70 wt % minifiller and 6 wt % nanofiller was the lowest. When the microfiller content was decreased from 6 wt % to 0 wt %, the contrast ratio decreased 6-9%. Energy-filtering transmission electron microscopy images indicated that the contrast ratio of experimental composites is related to the distribution morphology of the filler particles in the resin matrix.

Determination of phosphorylated and O-glycosylated sites by chemical targeting (CTID) at ambient temperature

In the analytical approach called chemically targeted identification (CTID), peptides containing phosphorylated or glycosylated serine and threonine underwent beta-elimination to produce an unsaturated double bond. Nucleophilic addition of 2-aminoethanethiol to this bond occurred, yielding aminoethylcysteine. Thus, sites containing posttranslational modifications were made susceptible to lysine endopeptidase. Structural information could then be obtained by mass analysis of the proteolytic products. The method was demonstrated by the analysis of beta-casein tryptic digest peptides and an O-glycosylated peptide. Contrary to an earlier report, the glycopeptide was found to react with essentially the same kinetics as phosphopeptides. Conversion of all five phosphoserines in residues 15, 17, 18, 19, and 35 in N-terminal tryptic phosphopeptides from bovine beta-casein were followed by monitoring the time course of the addition reaction. The chemistry proceeded rapidly at room temperature with a half-reaction time of 15 min. No side reaction products were observed. However, care had to be taken to minimize all counterions, which either precipitate barium or neutralize the base. In the case of 2-aminoethanethiol, excess Ba(OH)2 was needed to offset the effect of the hydrochloride. Alternatively, pre-incubation with base followed by nucleophilic addition was found to work satisfactorily. The use of water-soluble thiol allowed the procedure to be carried out in the solid phase, with a micro pipet greatly facilitating sample cleanup.

Effect of Ca2+, Ba2+, and Sr2+ on alginate microbeads

Microcapsules of alginate cross-linked with divalent ions are the most common system for cell immobilization. In this study, we wanted to characterize the effect of different alginates and cross-linking ions on important microcapsule properties. The dimensional stability and gel strength increased for high-G alginate gels when exchanging the traditional Ca2+ ions with Ba2+. The use of Ba2+ decreased the size of alginate beads and reduced the permeability to immunoglobulin G. Strontium gave gels with characteristics lying between calcium and barium. Interestingly, high-M alginate showed an opposite behavior in combination with barium and strontium as these beads were larger than beads of calcium-alginate and tended to swell more, also resulting in increased permeability. Binding studies revealed that different block structures in the alginate bind the ions to a different extent. More specifically, Ca2+ was found to bind to G- and MG-blocks, Ba2+ to G- and M-blocks, and Sr2+ to G-blocks solely.

Initial experience with magnetic resonance fluoroscopy in the evaluation of oesophageal motility disorders. Comparison with manometry and barium fluoroscopy

The aim of this paper was to assess the diagnostic value of magnetic resonance (MR) fluoroscopy in the study of oesophageal motility disorders and to compare MR fluoroscopy results with those of manometry and barium contrast radiography. Twenty-five subjects referred for dysphagia and three patients in follow-up after pneumatic dilatation of the lower oesophageal sphincter to treat severe achalasia underwent esophageal manometry, barium contrast radiography and MR fluoroscopy. Examinations were performed on a 1.5 T scanner. Dynamic turbo- fast low angle shot (turbo-FLASH) sequences acquired during oral contrast agent administration were used to perform MR fluoroscopy. MR fluoroscopy correctly diagnosed achalasia in nine patients, uncoordination of esophageal body motility in ten and scleroderma oesophagus in one. Diagnostic performance was satisfactory, with a sensitivity of 87.5% and a specificity of 100% in the general depiction of motility alterations. Our work demonstrates that MR fluoroscopic examination in subject affected by oesophageal motility disorders is feasible and can properly depict motility and morphology alterations, achieving correct diagnosis in the majority of cases. Studies on larger populations are necessary to obtain statistically significant results.