Molybdenum-Oxysulfide-Functionalized MgAl-Layered Double Hydroxides─A Sorbent for Selenium Oxoanions.

Effective removal of chemically toxic selenium oxoanions at high-capacity and trace levels from contaminated water remains a challenge in current scientific pursuits. Here, we report the functionalization of the MgAl layered double hydroxide with molybdenum-oxysulfide (MoO2S2) anion, referred to as LDH-MoO2S2, and its potential to sequester SeVIO42- and SeIVO32- from aqueous solution. LDH-MoO2S2 nanosheets were synthesized by an ion exchange method in solution. Synchrotron X-ray pair distribution function (PDF) and extended X-ray absorption fine structure (EXAFS) revealed an unexpected transformation of the MoO2S22- to Mo2O2S62- like species during the intercalation process. LDH-MoO2S2 is remarkably efficient in removing SeO42- and SeO32- ions from the ppm to trace level (≤10 ppb), with distribution constant (Kd) ranging from 104 to 105 mL/g. This material showed exceptionally high sorption capacities of 237 and 358 mg/g for SeO42- and SeO32-, respectively. Furthermore, LDH-MoO2S2 demonstrates substantial affinity and efficiency to remove SeO32-/SeO42- even in the presence of competitive ions from contaminated water. Hence, the removal of selenium (VI/IV) oxoanions collectively occurs through reductive precipitation and ion exchange mechanisms. This work provides significant insights into the chemical structure of the MoO2S2 anion into LDH and emphasizes its exceptional potential for high-capacity selenium removal and positioning it as a premier sorbent for selenium oxoanions.

Amorphous K-Co-Mo-Sx Chalcogel: A Synergy of Surface Sorption and Ion-Exchange.

Chalcogel represents a unique class of meso- to macroporous nanomaterials that offer applications in energy and environmental pursuits. Here, the synthesis of an ion-exchangeable amorphous chalcogel using a nominal composition of K2 CoMo2 S10 (KCMS) at room temperature is reported. Synchrotron X-ray pair distribution function (PDF), X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) reveal a plausible local structure of KCMS gel consisting of Mo5+ 2 and Mo4+ 3 clusters in the vicinity of di/polysulfides which are covalently linked by Co2+ ions. The ionically bound K+ ions remain in the percolating pores of the Co-Mo-S covalent network. XANES of Co K-edge shows multiple electronic transitions, including quadrupole (1s→3d), shakedown (1s→4p + MLCT), and dipole allowed 1s→4p transitions. Remarkably, despite a lack of regular channels as in some crystalline solids, the amorphous KCMS gel shows ion-exchange properties with UO2 2+ ions. Additionally, it also presents surface sorption via [S∙∙∙∙UO2 2+ ] covalent interactions. Overall, this study underscores the synthesis of quaternary chalcogels incorporating alkali metals and their potential to advance separation science for cations and oxo-cationic species by integrating a synergy of surface sorption and ion-exchange.

Effect of miniscrew placement height on the distribution of biological forces produced by clear aligner for mandibular molar distalization / 口腔疾病防治

Objective@#To explore the effect of different miniscrew placement heights on the distribution of biological forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization, to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.@*Methods@#Mimics, GeomagicStudio 2017, SolidWorks 2016, and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the following six working conditions: working condition 1 was the control group without miniscrews; working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm, 7 mm, 4 mm, and 1 mm from the top of the alveolar crest, respectively; working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.@*Results@#On the sagittal axis, miniscrew anchorage caused distal displacement of all teeth. Compared to the control group, in the miniscrew group, the displacement of the anterior molars exceeded that of the second molars. On the vertical axis, the result in the control group was similar to backward bending; the results in the miniscrew groups resembled the effect of a lever, lowering the lateral incisors and canines and raising the central incisors and first premolars. On the coronal axis, the second premolars and the first molars showed lingual displacement in the control group, and only the premolars and first molars showed lingual displacementin the miniscrew groups. The canines were the teeth that were most strongly affected by the change in miniscrew placement height.@*Conclusion@#The higher the miniscrew position is, the stronger the protective effect on the anterior anchorage. According to the miniscrew placement height, the mandibular arch should be properly narrowed, the central incisors and first premolars should be lowered, and the lateral incisors and canines should be raised when designing clinical treatments.

Meta-analysis of the efficacy of invisible orthodontic appliances for maxillary molar distalization in adult patients / 口腔疾病防治

Objective@#To evaluate the clinical efficacy of invisible orthodontic appliances without brackets for the distal movement of maxillary molars to improve the ability of orthodontists to predict treatment outcomes.@*Methods@#Web of Science, Cochrane Library, Embase, PubMed, Wanfang Database, CNKI Database, and VIP Database were searched for studies investigating the efficacy of invisible orthodontic appliances for distal movement of maxillary molars in adult patients and published from database inception to August 1, 2023. A total of three researchers screened the studies and evaluated their quality and conducted a meta-analysis of those that met quality standards.@*Results@#This study included 13 pre- and postcontrol trials with a total sample size of 281 patients. The meta-analysis revealed no significant differences in the sagittal or vertical parameters of the jawbone after treatment when compared with those before treatment (P>0.05). The displacement of the first molar was MD=-2.34, 95% CI (-2.83, -1.85); the displacement was MD=-0.95, 95% CI (-1.34, -0.56); and the inclination was MD=-2.51, 95% CI (-3.56, -1.46). There was a statistically significant difference in the change in sagittal, vertical, and axial tilt of the first molar before and after treatment. After treatment, the average adduction distance of the incisors was MD=-0.82, 95% CI (-1.54, -0.09), and the decrease in lip inclination was MD=-1.61, 95% CI (-2.86, -0.36); these values were significantly different from those before treatment (P<0.05).@*Conclusion@#Invisible orthodontic appliances can effectively move the upper molars in a distal direction and control the vertical position of the molars. When the molars move further away, there is some degree of compression and distal tilt movement, which is beneficial for patients with high angles. The sagittal movement of incisors is beneficial for improving the patient's profile.

The displacement of teeth and stress distribution on periodontal ligament under different upper incisors proclination with clear aligner in cases of extraction: a finite element study.

OBJECTIVES: To investigate the displacement of dentition and stress distribution on periodontal ligament (PDL) during retraction and intrusion of anterior teeth under different proclination of incisors using clear aligner (CA) in cases involving extraction of the first premolars. METHODS: Models were constructed, consisting of the maxilla, PDLs, CA and maxillary dentition without first premolars. These models were then imported to finite element analysis (FEA) software. The incisor proclination determined the division of the models into three groups: Small torque (ST) with U1-SN = 100°, Middle torque (MT) with U1-SN = 110°, and High torque (HT) with U1-SN = 120°. Following space closure, a 200 g intrusion force was applied at angles of 60°, 70°, 80°, and 90° to the occlusal plane, respectively. RESULTS: CA therapy caused lingual tipping and extrusion of incisors, mesial tipping and intrusion of canines, and mesial tipping of posterior teeth in each group. As the proclination of incisors increased, the incisors presented more extrusion and minor retraction, and the teeth from the canine to the second molar displayed an increased tendency of intrusion. The peak Von Mises equivalent stress (VMES) value successively decreased from the central incisor to the canine and from the second premolar to the second molar, and the VMES of the second molar was the lowest among the three groups. When the angle between the intrusion force and occlusal plane got larger, the incisors exhibited greater intrusion but minor retraction. CONCLUSIONS: The "roller coaster effect" usually occurred in cases involving premolar extraction with CA, especially in patients with protruded incisors. The force closer to the vertical direction were more effective in achieving incisor intrusion. The stress on PDLs mainly concentrated on the cervix and apex of incisors during the retraction process, indicating a possibility of root resorption.

Three-dimensional finite element study of mandibular first molar distalization with clear aligner.

OBJECTIVES: This study aimed to construct the finite element model of the mandibular first molar with the invisible appliance and explore the dentition movement characteristics of the mandibular first molar when using micro-implant anchorage and different initial positions of the first molar. METHODS: Models of the mandible, tooth, periodontal membrane, and invisible appliance were constructed using cone beam computed tomography (CBCT) data. The two groups were divided into the non-anchorage group and the micro-implant group (between the roots of the first molar and the second molar) based on whether the elastic traction of the micro-implant was assisted or not. The two groups were divided into the following conditions based on the starting position of the first molar: Working condition 1: the distance between the first molar and the second premolar was 0 mm; working condition 2: the distance between the first molar and the second premolar was 1 mm; working condition 3: the distance between the first molar and the second premolar was 2 mm; working condition 4: the distance between the first molar and the second premolar was 3 mm. The data characte-ristics of total displacement and displacement in each direction of dentition were analyzed. RESULTS: In the non-ancho-rage group, all the other teeth showed reverse movement except for the first molar which was moved distally. Meanwhile, in the micro-implant group, except for a small amount of mesial movement of the second molar in wor-king condition 1, the whole dentition in other working conditions presented distal movement and anterior teeth showed lingual movement, among which the distal displacement of the first molar in working condition 4 was the largest. With the change of the initial position of the first molar to the distal, the movement of the first molar to the distal, the premolar to the mesial, and the anterior to the lip increased, while the movement of the second molar to the mesial decreased. CONCLUSIONS: The micro-implant can effectively protect the anterior anchorage, increase the expression rate of molar distancing, and avoid the round-trip movement of the second molar. The initial position of the first molar movement is related to the amount of distancing and the remaining tooth movement.

Mandibular advancement with clear aligners and functional appliances in the treatment of skeletal Classâ ¡malocclusion: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group. METHODS: PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis. RESULTS: Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group. CONCLUSIONS: The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.

Removal of CrO42-, a Nonradioactive Surrogate of 99TcO4-, Using LDH-Mo3S13 Nanosheets.

Removal of chromate (CrO42-) and pertechnetate (TcO4-) from the Hanford Low Activity Waste (LAW) is beneficial as it impacts the cost, life cycle, operational complexity of the Waste Treatment and Immobilization Plant (WTP), and integrity of vitrified glass for nuclear waste disposal. Here, we report the application of [MoIV3S13]2- intercalated layer double hydroxides (LDH-Mo3S13) for the removal of CrO42- as a surrogate for TcO4-, from ppm to ppb levels from water and a simulated LAW off-gas condensate of Hanford's WTP. LDH-Mo3S13 removes CrO42- from the LAW condensate stream, having a pH of 7.5, from ppm (∼9.086 × 104 ppb of Cr6+) to below 1 ppb levels with distribution constant (Kd) values of up to ∼107 mL/g. Analysis of postadsorbed solids indicates that CrO42- removal mainly proceeds by reduction of Cr6+ to Cr3+. This study sets the first example of a metal sulfide intercalated LDH for the removal of CrO42-, as relevant to TcO4-, from the simulated off-gas condensate streams of Hanford's LAW melter which contains highly concentrated competitive anions, namely F-, Cl-, CO32-, NO3-, BO33-, NO2-, SO42-, and B4O72-. LDH-Mo3S13's remarkable removal efficiency makes it a promising sorbent to remediate CrO42-/TcO4- from surface water and an off-gas condensate of nuclear waste.

Universal Surface Passivation of Organic-Inorganic Halide Perovskite Films by Tetraoctylammonium Chloride for High-Performance and Stable Perovskite Solar Cells.

The power conversion efficiency (PCE) of perovskite solar cells has been showing rapid improvement in the last decade. However, still, there is an unarguable performance deficit compared with the Schockley-Queisser (SQ) limit. One of the major causes for such performance discrepancy is surface and grain boundary defects. They are a source of nonradiative recombination in the devices that not only causes performance loss but also instability of the solar cells. In this study, we employed a direct postsurface passivation strategy at mild temperatures to modify perovskite layer defects using tetraoctylammonium chloride (TOAC). The passivated perovskite layers have demonstrated extraordinary improvement in photoluminescence and charge carrier lifetimes compared to their control counterparts in both Cs0.05(FAPbI3)0.83(MAPbBr3)0.17 and MAPbI3-type perovskite layers. The investigation on electron-only and hole-only devices after TOAC treatment revealed suppressed electron and hole trap density of states. The electrochemical study demonstrated that TOAC treatment improved the charge recombination resistance of the perovskite layers and reduced the charge accumulation on the surface of perovskite films. As a result, perovskite solar cells prepared by TOAC treatment showed a champion PCE of 21.24% for the Cs0.05(FAPbI3)0.83(MAPbBr3)0.17-based device compared to 19.58% without passivation. Likewise, the PCE of MAPbI3 improved from 18.09 to 19.27% with TOAC treatment. The long-term stability of TOAC-passivated perovskite Cs0.05(FAPbI3)0.83(MAPbBr3)0.17 devices has retained over 97% of its initial performance after 720 h in air.

A Pilot Study on High Wavenumber Raman Analysis of Human Dental Tissues.

Water plays a critical role in dental tissues including enamel and dentin. The characterization of water structure analysis was primarily conducted by nuclear magnetic resonance. Raman spectroscopy is a powerful analytic technology with capability for structure analysis in materials. However, acquiring high wavenumber Raman signals from dental tissues was challenging due to either the fluorescence interference under laser illumination or reduced sensitivity of CCD detectors. In this study, we demonstrate a pilot research on high wavenumber Raman analysis in dental tissues using a customized Raman spectrometer based on an InGaAs detector. A signal located at 3570 cm-1 is found dominating the O-H region Raman spectra of enamel but is barely detectable from dentin. The profiles of the high wavenumber region Raman spectra changes with the locations in enamel, as well as the polarization of the excitation laser beam. The results suggest that the size or crystallinity differences of hydroxyapatite crystals are the main cause of the spectral variation from dentin to enamel, and could be partially responsible for the variation among different locations in enamel.

Laboratory simulation of uranium metal corrosion in different soil moisture regimes.

A novel laboratory simulation system has been developed for the study of the corrosion of uranium metal in soils. Corrosion and transportation of depleted uranium (DU) as the metal undergoes weathering as a buried material within the soil environment. The corrosion of uranium metal in soil was not well understood due to the gas-liquid-solid phase of the soil. This study presents a novel method to investigate the change of uranium species during the process of process of oxidation of metallic uranium in these environments. Compared with other techniques used for the study of environmental corrosion of metals in soils, this method has the advantage of low secondary uranium pollution, no energy consumption, and ease of operation. The simulation system has been used for the following studies: •Simultaneously simulate the corrosion of uranium metal in different soil moisture regimes•Study the influence of biogeochemical factors on the corrosion of uranium metal•Investigate the change of uranium species during oxidation.

Schisandrin A and B enhance the dentate gyrus neurogenesis in mouse hippocampus.

Schisandrin A and B (Sch A and B) are the main effective components of Schisandra chinensis (S. chinensis), which is traditionally used to enhance mental and intellectual functions in eastern Asia. Previously, we reported Sch A and B remarkably affect adult neurogenesis in the subventricular zone of mouse lateral ventricle. Since the neurogenesis in the hippocampal dentate gyrus (DG) is more important to learning, memory and cognition, here we further examined their effects on the adult DG neurogenesis. Phosphohistone H3 (PHH3) immunostaining showed that Sch B significantly enhanced the cell proliferation in the DG. Glial fibrillary acidic protein (GFAP, mostly labels astrocytes and some stem cells) staining was used to further identify the proliferating cell type. Dramatically, increases of GFAP+ cells in both Sch A and B treated groups were observed. What's more, the total numbers of the mature neurons labeled by neuron-specific nuclear protein (NeuN) were also increased in both Sch A and B treated groups compared with the controls. Together, Sch A and B enhance the adult DG neurogenesis by increasing astrocytes/stem cells and improving the survival and maturation of DG neurons. Our study shed a new light on the neuropharmacological functions of the herbal medicine S. chinensis.

Cryopreservation of calf testicular tissues with knockout serum replacement.

To enrich bovine gonocytes from cryopreserved testicular tissues, the cryoprotection effects of the freezing media containing knockout serum replacement (KSR) were examined. Using Minimum essential medium (MEM) + 10% dimethyl sulfoxide (Me2SO) as the basic medium, calf testicular tissues were cryopreserved in media containing 0, 5, 10, 20, 40, 90% KSR and 5% fetal bovine serum (FBS) respectively. Morphologically, the seminiferous cords and interstitium were well preserved in all groups. The gonocytes were all glial cell line-derived neurotrophic factor (GDNF) family receptor α-1 (GFRα-1) positive. The recovery rates in all KSR groups were higher than that of the 10% Me2SO group, while comparable to the 5% FBS group. The enriched gonocytes expressed gonocyte marker GFRα-1 typically. Collectively, supplementation of 5-10% KSR can achieve comparable cryoprotective effects with using 5% FBS, which is useful in future study due to its defined formulation that is more consistent in quality and stable in supply.

Inhibiting transforming growth factor-ß signaling regulates in vitro maintenance and differentiation of bovine bone marrow mesenchymal stem cells.

Bovine bone marrow mesenchymal stem cells (bBMSC) are potential stem cell source which can be used for multipurpose. However, their application is limited because the in vitro maintenance of these cells is usually accompanied by aging and multipotency losing. Considering transforming growth factor-ß (TGF-ß) pathway inhibitor Repsox is beneficial for cell reprogramming, here we investigated its impacts on the maintenance and differentiation of bBMSC. The bBMSC were enriched and characterized by morphology, immunofluorescent staining, flow cytometry, and multilineage differentiation. The impacts of Repsox on their proliferation, apoptosis, cell cycle, multipotency, and differentiation were examined by Cell Counting Kit-8 (CCK-8), real-time polymerase chain reaction, induced differentiation and specific staining. The results showed that highly purified cluster of diffrentiation 73+ (CD73 + )/CD90 + /CD105 + /CD34 - /CD45 - bBMSC with adipogenic, osteogenic, and chondrogenic differentiation capacities were enriched. Repsox treatments (5 µM, 48 hr) enhanced the messenger RNA mRNA levels of the proliferation gene (telomerase reverse transcriptase [ TERT]; basic fibroblast growth factor [ bFGF]), apoptosis-related gene ( bax and Bcl2), antiapoptosis ratio ( Bcl2/bax), and pluripotency marker gene ( Oct4, Sox2, and Nanog), instead of changing the cell cycle, in bBMSC. Repsox treatments also enhanced the osteogenic differentiation but attenuated the chondrogenic differentiation of bBMSC, concomitant with decreased Smad2 and increased Smad3/4 expressions in TGF-ß pathway. Collectively, inhibiting TGF-ß/Smad signaling by Repsox regulates the in vitro maintenance and differentiation of bBMSC.

Three-dimensional finite element analysis of maxillary protraction with labiolingual arches and implants.

INTRODUCTION: In this study, we aimed to evaluate the effects of maxillary protraction using traditional labiolingual arches and implant-type protraction devices before orthopedic treatment of patients with skeletal Class III malocclusion. METHODS: A 3-dimensional finite element model of the maxillofacial bones with high biologic similarity and including the sutures was constructed. Through stress and displacement calculations, a biomechanical study was performed for the maxillofacial bones, mandible, and sutures. RESULTS: We quantified detailed changes in the sutures with 2 protraction methods to analyze their effects on the growth of the maxillofacial bones. CONCLUSIONS: (1) The labiolingual arch is suitable for skeletal Class III patients with crossbite and deep overbite. The frontomaxillary and zygomaticomaxillary sutures played major roles in the forward displacement and counterclockwise rotation of the maxilla. The temporozygomatic and pterygopalatine sutures did not change significantly. (2) The implant type of protraction device is suitable for skeletal Class III patients with crossbite and open bite. Both the frontomaxillary and zygomaticomaxillary sutures played decisive roles in the forward displacement and clockwise rotation of maxilla. The temporozygomatic and pterygopalatine sutures showed small changes. (3) The labiolingual arch caused less stimulatory growth on the maxilla, whereas the implant caused greater stimulatory growth on the maxilla. Protraction with the labiolingual arch is more suitable for early skeletal Class III patients at a younger age; protraction with an implant is applicable to skeletal Class III patients in the late mixed dentition or early permanent dentition.

[Three-dimensional finite-element analysis of maxillary protraction based on labiolingual appliance].

OBJECTIVE: This study aims to analyze the biomechanical effects of four sutures that are related to maxillary growth during a maxillary protraction treatment cycle based on labiolingual appliance. METHODS: A three-dimensional simulation of labiolingual appliance was performed based on a three-dimensional finite-element maxillofacial model combined with solid-modeled sutures. RESULTS: The displacement and stress distributions were calculated. The labiolingual appliance was suitable for patients with underbites or deep overbites. Sutura frontomaxillaris and sutura zygomaticomaxillaris were vital to the forward displacement and counterclockwise rotation of the maxillary. The changes in sutura zygomaticotemporalis and sutura palatine were not significant. CONCLUSION: The influences of the labiolingual appliance on the sutures during the treatment cycle of maxillary protraction can be effectively simulated by the three-dimensional finite-element maxillofacial model.

[Influence of different surface treatments on porcelain surface topography].

OBJECTIVE: To evaluate the influence of different surface treatments on porcelain surface topography. METHODS: Metal ceramic prostheses in 6 groups were treated according to the different surface treatment methods, and the surface topography was observed through scanning electron microscope (SEM). Group A was the control one (untreated), group B was etched by 9.6% hydrofluoric acid(HF), group C was deglazed by grinding and then etched by 9.6% HF, group D was treated with Nd: YAG laser irradiation(0.75 W) and HF etching, group E was treated with Nd: YAG laser irradiation (1.05 W) and HF etching, and group F was treated with laser irradiation (1.45 W) and HF etching. RESULTS: Surface topography was different in different groups. A lot of inerratic cracks with the shapes of rhombuses and grid, and crater with a shape of circle were observed on the ceramic surface after treatment with energy parameters of 1.05 W Nd: YAG laser irradiation and 9.6% HF etching (group E). Surface topography showed a lot of concaves on the inner wall of the cracks, and the concaves with diameter of 1-5 microm could be observed on the inner wall of the holes, which had a diameter of 20 microm under SEM. CONCLUSION: The use of Nd: YAG laser irradiation with the energy parameters of 1.05 W and the HF with a concentration of 9.6% can evenly coarsen the porcelain surface, that is an effective surface treatment method.

Metal-binding properties and structural characterization of a self-assembled coiled coil: formation of a polynuclear Cd-thiolate cluster.

This paper describes the design, characterization, and metal-binding properties of a 32-residue polypeptide called AQ-C16C19. The sequence of this peptide is composed of four repeats of the seven residue sequence Ile-Ala-Ala-Leu-Glu-Gln-Lys but with a Cys-X-X-Cys metal-binding motif substituted at positions 16-19. Size exclusion chromatography with multiangle light scattering detection (SEC-MALS) and circular dichroism (CD) spectroscopy studies showed that the apo peptide exhibits a pH-dependent oligomerization state in which a three-stranded α-helical coiled coil is dominant between pH5.4 and 8.5. The Cd(2+)-binding properties of the AQ-C16C19 peptide were studied by ultraviolet-visible spectroscopy (UV-vis), electrospray ionization mass spectrometry (ESI MS), and (113)Cd NMR techniques. The holoprotein was found to contain a polynuclear cadmium-thiolate center formed within the hydrophobic core of the triple-stranded α-helical coiled-coil structure. The X-ray crystal structure of the Cd-loaded peptide, resolved at 1.85Å resolution, revealed an adamantane-like configuration of the polynuclear metal center consisting of four cadmium ions, six thiolate sulfur ligands from cysteine residues and four oxygen-donor ligands. Three of these are from glutamic acid residues and one is from an exogenous water molecule. Thus, each cadmium ion is coordinated in a distorted tetrahedral S(3)O geometry. The metal cluster was found to form cooperatively at pH5.4 but in a stepwise fashion at pH>7. The results demonstrate that synthetic coiled-coils can be designed to incorporate multinuclear metal clusters, a proof-of-concept for their potential use in developing synthetic metalloenzymes and multi-electron redox agents.

Enhanced Photodynamic Selectivity of Nano-Silica-Attached Porphyrins Against Breast Cancer Cells.

The synthesis and characterization of bare silica (4 nm in diameter) nanoparticle-attached meso-tetra(N-methyl-4-pyridyl)porphine (SiO(2)-TMPyP, 6 nm in diameter) are described for pH-controllable photosensitization. Distinguished from organosilanes, SiO(2) nanoparticles were functionalized as a potential quencher of triplet TMPyP and/or singlet oxygen ((1)O(2)) at alkaline pH, thereby turning off sensitizer photoactivity. In weak acidic solutions, TMPyP was released from SiO(2) surface for efficient production of (1)O(2). By monitoring (1)O(2) luminescence at 1270 nm, quantum yields of (1)O(2) production were found to be pH-dependent, dropping from ~ 0.45 in a pH range of 3-6 to 0.08 at pH 8-9, which is consistent with pH-dependent adsorption behavior of TMPyP on SiO(2) surface. These features make bare SiO(2)-attached cationic porphyrin a promising candidate for use in PDT for cancer treatment in which efficient (1)O(2) production at acidic pH and sensitizer deactivation at physiological pH are desirable. The enhanced therapeutic selectivity was confirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests and trypan blue exclusion tests of cell viability in breast cancer cell lines. Bimolecular quenching rate constants of (1)O(2) by free TMPyP, SiO(2) and SiO(2)-TMPyP nanoparticles were also determined.

[Three dimensional finite element analysis of tooth movement tendency in maxilla using mini-screw cooperated with upper accentuated-curve to close tooth space].

OBJECTIVE: In order to find out the cause of molar intrusion and how to avoid molar intrusion, we analyze the movement tendency of tooth by changing the angles of upper accentuated-curve and the height of free traction hook. METHODS: Spiral CT scanning and Mimics 10.0 software were employed in this study to construct the three dimensional finite element model of maxillary teeth, periodontal ligaments and alveolar bone as well as the inch stainless steel upper accentuated-curve archwires with different angles (5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees) and the free traction hook with different height (2.1, 4.0, 5.5 mm). By exerting 1.5 N backward force to analysis the displacement trend of maxillary tooth. RESULTS: Upper accentuated-curve archwires made the incisors labially tip, intruse, distally upright and mesilabially torsion; made the canines labially tip, prolong, mesial-tipped and mesi-labially torsion; made the second premolars and the first molars buccal tip, intruse, distal upright and mesi-labially torsion. With the angle of upper accentuated-curve archwires increased, all tooth movement tendency increased; while with the height of free traction hook increased, all tooth movement tendency decreased. CONCLUSION: When the angle of upper accentuated-curve archwires increased, the extent of molar intrusion increased, but when the height of free traction hook increased, the degree of molar intrusion decreased. The degree of molar intrusion was minimum using 5 degrees upper accentuated-curve archwires cooperated with 5.5 mm free traction hook.