Application of Weak-Beam Dark-Field STEM for Dislocation Loop Analysis †.

Nanoscale dislocation loops formed by irradiation can significantly contribute to both irradiation hardening and embrittlement of materials when subjected to extreme nuclear reactor environments. This study explores the application of weak-beam dark-field (WBDF) scanning transmission electron microscopy (STEM) methods for quantitative irradiation-induced defect analysis in crystalline materials, with a specific focus on dislocation loop imaging and analysis. A high-purity Fe-5 wt% Cr model alloy was irradiated with 8 MeV Fe2+ ions at 450°C to a fluence of 8.8 × 1019 m-2, inducing dislocation loops for analysis. While transmission electron microscopy (TEM) has traditionally been the primary tool for dislocation imaging, recent advancements in STEM technology have reignited interest in using STEM for defect imaging. This study introduces and compares three WBDF STEM methods, demonstrating their effectiveness in suppressing background contrasts, isolating defect information for dislocation loop type classification, providing finer dislocation line images for small loop analysis, and presenting inside-outside contrast for identifying loop nature. Experimental findings indicate that WBDF STEM methods surpass traditional TEM approaches, yielding clearer and more detailed images of dislocation loops. The study concludes by discussing the potential applications of WBDF STEM techniques in defect analysis, emphasizing their adaptability across various material systems beyond nuclear materials.

Stimulation phosphatidylinositol 3-kinase/protein kinase B signaling by Porphyromonas gingivalis lipopolysacch aride mediates interleukin-6 and interleukin-8 mRNA/protein expression in pulpal inflammation.

BACKGROUND/PURPOSE: The signaling mechanisms for Porphyromonas gingivalis lipopolysaccharide (PgLPS)-induced inflammation in human dental pulp cells are not fully clarified. This in vitro study aimed to evaluate the involvement of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in PgLPS-induced pulpal inflammation. METHODS: Human dental pulp cells (HDPCs) were challenged with PgLPS with or without pretreatment and coincubation with a PI3K/Akt inhibitor (LY294002). The gene or protein levels of PI3K, Akt, interleukin (IL)-6, IL-8, alkaline phosphatase (ALP), osteocalcin and osteonectin were analyzed by reverse transcription polymerase chain reaction (PCR), real-time PCR, western blotting, and immunofluorescent staining. In addition, an enzyme-linked immunosorbent assay was used to analyze IL-6 and IL-8 levels in culture medium. RESULTS: In response to 5 µg/ml PgLPS, IL-6, IL-8, and PI3K, but not Akt mRNA expression of HDPCs, was upregulated. IL-6, IL-8, PI3K, and p-Akt protein levels were stimulated by 10-50 µg/ml of PgLPS in HDPCs. PgLPS also induced IL-6 and IL-8 secretion at concentrations higher than 5 µg/ml. Pretreatment and co-incubation by LY294002 attenuated PgLPS-induced IL-6 and IL-8 mRNA expression in HDPCs. The mRNA expression of ALP, but not osteocalcin and osteonectin, was inhibited by higher concentrations of PgLPS in HDPCs. CONCLUSION: P. gingivalis contributes to pulpal inflammation in HDPCs by dysregulating PI3K/Akt signaling pathway to stimulate IL-6 and IL-8 mRNA/protein expression and secretion. These results are useful for understanding the pulpal inflammation and possible biomarkers of inflamed pulp diagnosis and treatment.

Factors associated with positive aspects of caregiving experiences among family caregivers of persons living with dementia in Taiwan: A cross-sectional study.

This study examined the associated factors of positive aspects of caregiving experience among family caregivers of persons living with dementia in Taiwan. This cross-sectional correlational study recruited dyads of primary family caregivers of persons living with dementia by convenience sampling from dementia care centers in northern Taiwan from September 9, 2020, to June 20, 2021. A total of 100 dyads who met inclusions criteria agreed to participate in the study. Significant predictors of positive aspects of caregiving experience were scores of dementia behavior disturbance (t=-3.63, p =<.001), a spousal caregiver (t=2.83, p =.006), and the subscale score for satisfaction on the functional social support (t=2.62, p =.01). Our findings suggest prevention and treatment of dementia behavior disturbance for persons living with dementia, improving satisfaction with functional social support, and focusing on non-spousal caregivers could enhance experiences of positive caregiving for family caregivers.

The Application of an Omentum Graft or Flap in Spinal Cord Injury.

BACKGROUND: Spinal cord injury (SCI) causes a primary injury at the lesion site and triggers a secondary injury and prolonged inflammation. There has been no definitive treatment till now. Promoting angiogenesis is one of the most important strategies for functional recovery after SCI. The omentum, abundant in blood and lymph vessels, possesses the potent ability of tissue regeneration. METHODS: The present work examines the efficacy of autologous omentum, either as a flap (with vascular connection intact) or graft (severed vascular connection), on spinal nerve regeneration. After contusive SCI in rats, a thin sheath of omentum was grafted to the injured spinal cord. RESULTS: Omental graft improved behavior scores significantly from the 3rd to 6th week after injury (6th week, 5.5 ± 0.5 vs. 8.6 ± 1.3, p < 0.05). Furthermore, the reduction in cavity and the preservation of class III ß-tubulin-positive nerve fibers in the injury area was noted. Next, the free omental flap was transposed to a completely transected SCI in rats through a pre-implanted tunnel. The flap remained vascularized and survived well several weeks after the operation. At 16 weeks post-treatment, SCI rats with omentum flap treatment displayed the preservation of significantly more nerve fibers (p < 0.05) and a reduced injured cavity, though locomotor scores were similar. CONCLUSIONS: Taken together, the findings of this study indicate that treatment with an omental graft or transposition of an omental flap on an injured spinal cord has a positive effect on nerve protection and tissue preservation in SCI rats. The current data highlight the importance of omentum in clinical applications.

Improving the regenerative potential of olfactory ensheathing cells by overexpressing prostacyclin synthetase and its application in spinal cord repair.

BACKGROUND: Olfactory ensheathing cells (OEC), specialized glia that ensheathe bundles of olfactory nerves, have been reported as a favorable substrate for axonal regeneration. Grafting OEC to injured spinal cord appears to facilitate axonal regeneration although the functional recovery is limited. In an attempt to improve the growth-promoting properties of OEC, we transduced prostacyclin synthase (PGIS) to OEC via adenoviral (Ad) gene transfer and examined the effect of OEC with enhanced prostacyclin synthesis in co-culture and in vivo. Prostacyclin is a vasodilator, platelet anti-aggregatory and cytoprotective agent. RESULTS: Cultured OEC expressed high level of cyclooxygneases, but not PGIS. Infection of AdPGIS to OEC could selectively augument prostacyclin synthesis. When cocultured with either OEC or AdPGIS-OEC, neuronal cells were resistant to OGD-induced damage. The resulted OEC were further transplanted to the transected cavity of thoracic spinal cord injured (SCI) rats. By 6 weeks post-surgery, significant functional recovery in hind limbs occurred in OEC or AdPGIS-OEC transplanted SCI rats compared with nontreated SCI rats. At 10-12 weeks postgraft, AdPGIS-OEC transplanted SCI rats showed significantly better motor restoration than OEC transplanted SCI rats. Futhermore, regenerating fiber tracts in the distal spinal cord stump were found in 40-60% of AdPGIS-OEC transplanted SCI rats. CONCLUSIONS: Enhanced synthesis of prostacyclin in grafted OEC improved fiber tract regeneration and functional restoration in spinal cord injured rats. These results suggest an important potential of prostacyclin in stimulating OEC therapeutic properties that are relevant for neural transplant therapies.

[Ag20 {S2 P(OR)2 }12 ]: A Superatom Complex with a Chiral Metallic Core and High Potential for Isomerism.

The synthesis and structural determination of a silver nanocluster [Ag20 {S2 P(OiPr)2 }12 ] (2), which contains an intrinsic chiral metallic core, is produced by reduction of one silver ion from the eight-electron superatom complex [Ag21 {S2 P(OiPr)2 }12 ](PF6 ) (1) by borohydrides. Single-crystal X-ray analysis displays an Ag20 core of pseudo C3 symmetry comprising a silver-centered Ag13 icosahedron capped by seven silver atoms. Its n-propyl derivative, [Ag20 {S2 P(OnPr)2 }12 ] (3), can also be prepared by the treatment of silver(I) salts and dithiophosphates in a stoichiometric ratio in the presence of excess amount of [BH4 ](-) . Crystal structure analyses reveal that the capping silver-atom positions relative to their icosahedral core are distinctly different in 2 and 3 and generate isomeric, chiral Ag20 cores. Both Ag20 clusters display an emission maximum in the near IR region. DFT calculations are consistent with a description within the superatom model of an 8-electron [Ag13 ](5+) core protected by a [Ag7 {S2 P(OR)2 }12 ](5-) external shell. Two additional structural variations are predicted by DFT, showing the potential for isomerism in such [Ag20 {S2 P(OR)2 }12 ] species.

Ferrocene-Functionalized Cu(I)/Ag(I) Dithiocarbamate Clusters.

A series of compounds, namely, [Cu8(µ4-H){S2CNMeCH2Fc}6](PF6) (1), [Cu7(µ4-H) {S2CN(i)PrCH2Fc}6] (2), [Cu3{S2CN(Bz) (CH2Fc)}2(dppf)2](PF6) (3), and [Ag2{S2CNMe(CH2Fc)}2(PPh3)2] (4) (dppf = 1,1'-bis(diphenylphosphino)ferrocene), supported by multiferrocene assemblies, were synthesized. All the compounds were characterized by (1)H NMR, Fourier transform infrared, elemental analysis, and electrospray ionization mass spectrometry techniques. Single-crystal X-ray structural analysis revealed that 1 is a monocationic octanuclear Cu(I) cluster and that 2 is a neutral heptanuclear Cu(I) cluster with tetracapped tetrahedral (1) and tricapped tetrahedral (2) geometries entrapped with an interstitial hydride, anchored by six ferrocene units at the periphery of the core. Compounds 3 and 4 comprise trimetallic Cu(I) and dimetallic Ag(I) cores enfolded by four and two ferrocene moieties. Interestingly both chelating and bridging modes of binding are observed for dppf ligand in 3. Further the formation and isolation of polyhydrido copper clusters [Cu28H15{S2CN(i)PrCH2Fc}12](PF6) (5) and [Cu28H15{S2CN(n)Bu2}12](PF6) (7), stabilized by bulky ferrocenyl and n-butyl dithiocarbamate ligands, was demonstrated. They are readily identified by (2)H NMR studies on their deuterium analogues, [Cu28D15{S2CN(i)PrCH2Fc}12](PF6) (6) and [Cu28D15{S2CN(n)Bu2}12](PF6) (8). Though the structure details as well as spectroscopic characterizations of 5 are yet to be investigated, the compound 7 is fully characterized by variety of spectroscopy including single-crystal X-ray diffraction. The cyclic voltammetry studies for compounds 1, 2, and 4 display irreversible redox peaks for Fe(2+)/Fe(3+) couple wherein the reduction peaks are not well-resolved due to some adsorption of the complex onto the electrode surface.

Au-Au chemical bonding induced by UV irradiation of dinuclear gold(I) complexes: a computational study with experimental evidence.

Two luminescent dinuclear gold(I) species, namely diselenophosphinate [Au2{µ-Se2P((CH2)2Ph)2}2] and dithiophosphinate [Au2{µ-S2P((CH2)2Ph)2}2], exhibiting interesting structural, absorption and emission properties have been studied. In the solid state, both complexes exist in a dinuclear monomeric form, exhibiting no aurophilic interaction, and display similar photophysical properties. It is shown, using DFT computations, that Au-Au chemical bonding appears in the first excited state of these complexes, whereas such bonding does not exist in their ground state; Raman spectroscopy experiments, which bring to light the stretching of this new bond, confirm the theoretical results. Moreover, TDDFT computations permitted us to assign the observed absorption bands of the UV-visible spectra of the two species to LMCT transitions and to describe the emission.

Exploring the Charge-Transport and Optical Characteristics of Organic Doublet Radicals: A Theoretical and Experimental Study with Photovoltaic Applications.

Herein, we present a series of stable radicals containing a trityl carbon-centered radical moiety exhibiting interesting properties. The radicals demonstrate the most blue-shifted anti-Kasha doublet emission reported so far with high color purity (full width at half-maximum of 46 nm) and relatively high photoluminescence quantum yields of deoxygenated toluene solutions reaching 31%. The stable radicals demonstrate equilibrated bipolar charge transport with charge mobility values reaching 10-4 cm2/V·s at high electric fields. The experimental results in combination with the results of TD-DFT calculations confirm that the blue emission of radicals violates the Kasha rule and originates from higher excited states, whereas the bipolar charge transport properties are found to stem from the particularity of radicals to involve the same molecular orbital(s) in electron and hole transport. The radicals act as the efficient materials for interlayers, passivating interfacial defects and enhancing charge extraction in PSCs. Consequently, this leads to outstanding performance of PSC, with power conversion efficiency surpassing 21%, accompanied by a remarkable increase in open-circuit voltage and exceptional stability.

A nanospheric polyhydrido copper cluster of elongated triangular orthobicupola array: liberation of H2 from solar energy.

An unprecedented air-stable, nanospheric polyhydrido copper cluster, [Cu20H11(S2P(O(i)Pr)2)9] (1H), which is the first example of an elongated triangular orthobicupola array of Cu atoms having C3h symmetry, was synthesized and characterized. Its composition was primarily determined by electrospray ionization mass spectrometry, and it was fully characterized by (1)H, (2)H, and (31)P NMR spectroscopy and single-crystal X-ray diffraction (XRD). The structure of complex 1H can be expressed in terms of a trigonal-bipyramidal [Cu2H5](3-) unit anchored within an elongated triangular orthobicupola containing 18 Cu atoms, which is further stabilized by 18 S atoms from nine dithiophosphate ligands and six capping hydrides. The positions of the 11 hydrides revealed by low temperature XRD were supported by a density functional theory investigation on the simplified model [Cu20H11(S2PH2)9] with C3h symmetry. 1H is capable of releasing H2 gas upon irradiation with sunlight, under mild thermal conditions (65 °C), or in the presence of acids at room temperature.

[Ag7(H){E2P(OR)2}6] (E = Se, S): precursors for the fabrication of silver nanoparticles.

Reactions of Ag(I) salt, NH(4)(E(2)P(OR)(2)) (R = (i)Pr, Et; E = Se, S), and NaBH(4) in a 7:6:1 ratio in CH(2)Cl(2) at room temperature, led to the formation of hydride-centered heptanuclear silver clusters, [Ag(7)(H){E(2)P(OR)(2)}(6)] (R = (i)Pr, E = Se (3): R = Et; E = S(4). The reaction of [Ag(10)(E){E(2)P(OR)(2)}(8)] with NaBH(4) in CH(2)Cl(2) produced [Ag(8)(H){E(2)P(OR)(2)}(6)](PF(6)) (R = (i)Pr, E = Se (1): R = Et; E = S(2)), which can be converted to clusters 3 and 4, respectively, via the addition of 1 equiv of borohydride. Intriguingly clusters 1 and 2 can be regenerated via adding 1 equiv of Ag(CH(3)CN)(4)PF(6) to the solution of compounds 3 and 4, respectively. All complexes have been fully characterized by NMR ((1)H, (77)Se, (109)Ag) spectroscopy, UV-vis, electrospray ionization mass spectrometry (ESI-MS), FT-IR, thermogravimetric analysis (TGA), and elemental analysis, and molecular structures of 3(H) and 4(H) were clearly established by single crystal X-ray diffraction. Both 3(H) and 4(H) exhibit a tricapped tetrahedral Ag(7) skeleton, which is inscribed within an E(12) icosahedron constituted by six dialkyl dichalcogenophosphate ligands in a tetrametallic-tetraconnective (µ(2), µ(2)) bonding mode. Density functional theory (DFT) calculations on the models [Ag(7)(H)(E(2)PH(2))(6)] (E = Se: 3'; E = S: 4') yielded to a tricapped, slightly elongated tetrahedral silver skeleton, and time-dependent DFT (TDDFT) calculations reproduce satisfyingly the UV-vis spectrum with computed transitions at 452 and 423 nm for 3' and 378 nm for 4'. Intriguingly further reactions of [Ag(7)(H){E(2)P(OR)(2)}(6)] with 8-fold excess amounts of NaBH(4) produced monodisperse silver nanoparticles with an averaged particle size of 30 nm, which are characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and UV-vis absorption spectrum.

Shape modulation of octanuclear Cu(I) or Ag(I) dichalcogeno template clusters with respect to the nature of their encapsulated anions: a combined theoretical and experimental investigation.

M8L6 clusters (M = Cu(I), Ag(I); L = dichalcogeno ligand) are known for their ability to encapsulate various kinds of saturated atomic anions. Calculations on the models [M8(E2PH2)6](2+) (M = Cu(I), Ag(I); E = S, Se) and the ionic or neutral [M8(X)(E2PH2)6](q) (X = H, F, Cl, Br, O, S, Se, N, P, C) indicate that the cubic M8L6 cage adapts its shape for maximizing the host-guest bonding interaction. The interplay between size, covalent and ionic bonding favors either a cubic, tetracapped tetrahedral, or bicapped octahedral structure of the metal framework. Whereas the large third- and fourth-row main group anions maintain the cubic shape, a distortion toward a tetracapped tetrahedral arrangement of the metals occurs in the case of hydride, fluoride, and oxide. The distortion is strong in the case of hydride, weak in the case of fluoride, and intermediate in the case of oxide. Density functional theory (DFT) calculations predict a bicapped octahedral architecture in the case of nitride and carbide. These computational results are supported by X-ray structures, including those of new fluorine- and oxygen-containing compounds. It is suggested that other oxygen-containing as well as so far unknown nitride-containing clusters should be feasible. For the first time, the dynamical behavior of the encapsulated hydride has been investigated by metadynamics simulations. Our results clearly demonstrate that the interconversion mechanism between two identical tetracapped tetrahedral configurations occurs through a succession of M-H bonds breaking and forming which present very low activation energies and which involve a rather large number of intermediate structures. This mechanism is full in accordance with (109)Ag and (1)H state NMR measurements.

Anion encapsulation and geometric changes in hepta- and hexanuclear copper(I) dichalcogeno clusters: a theoretical and experimental investigation.

Whereas stable octanuclear clusters of the type M(I)8(E(∩)E)6 (M = Cu, Ag; E(∩)E = dithio or diseleno ligand) are known for being able to encapsulate a hydride or main-group anion under some circumstances, only the related hydride-containing heptanuclear [M(I)]7(H)(E(∩)E)6 and empty hexanuclear [M(I)]6(E(∩)E)6 species have been characterized so far. In this paper we investigate by the means of theoretical calculations and experiments the viability of empty and anion-centered clusters of the type [Cu(I)]7(X)(E(∩)E)6 and [Cu(I)]6(X)(E(∩)E)6 (X = vacancy, H or a main-group atom). The theoretical prediction for the existence of anion-containing heptanuclear species, the shape of which is modulated by the anion nature and size, have been fully confirmed by the synthesis and characterization of [Cu7(X){S2P(O(i)Pr)2}6] (X = H, Br). This consistency between experiment and theory allows us to predict the stability and shape-modulated structure of a whole series of [Cu(I)]7(X)(E(∩)E)6 (X = vacancy, H, O, S, halogen) and [Cu(I)]6(X)(E(∩)E)6 (X = H, halogen) clusters.

Highly Efficient Ternary Near-Infrared Organic Photodetectors for Biometric Monitoring.

Near-infrared (NIR) small-molecule acceptors that absorb at wavelengths of up to 1000 nm are attractive for applications in organic photodetectors (OPDs) and biometrics. In this study, we incorporated IEICO-4F as the third component for PffBT4T-2OD:PC71BM-based OPDs to provide an efficient NIR response while greatly suppressing the leakage current at reverse bias. By varying the blend ratio and thickness (250-600 nm), we obtained an NIR OPD displaying an ultralow dark-current density (JD = 2.62 nA cm-2), ultrahigh detectivity [D* = 7.2 × 1012 Jones (850 nm)], high sensitivity, and photoresponsivity covering the region from the ultraviolet to the NIR. We used tapping-mode atomic force microscopy, optical microscopy, grazing-incidence wide-angle X-ray scattering, and contact angle measurements to investigate the effect of IEICO-4F on the performance of the ternary OPDs. The low compatibility of PffBT4T-2OD and IEICO-4F, originating from weak intermolecular interactions, allowed us to manipulate the degree of phase separation between the donor and acceptor in the ternary blends, leading to an optimized blend morphology featuring efficient charge separation, transport, and collection. To demonstrate its applicability, we integrated our OPD with two light-emitting diodes and used the system for precisely calculated transmissive pulse oximetry.

A High-Accuracy Detection System: Based on Transfer Learning for Apical Lesions on Periapical Radiograph.

Apical Lesions, one of the most common oral diseases, can be effectively detected in daily dental examinations by a periapical radiograph (PA). In the current popular endodontic treatment, most dentists spend a lot of time manually marking the lesion area. In order to reduce the burden on dentists, this paper proposes a convolutional neural network (CNN)-based regional analysis model for spical lesions for periapical radiographs. In this study, the database was provided by dentists with more than three years of practical experience, meeting the criteria for clinical practical application. The contributions of this work are (1) an advanced adaptive threshold preprocessing technique for image segmentation, which can achieve an accuracy rate of more than 96%; (2) a better and more intuitive apical lesions symptom enhancement technique; and (3) a model for apical lesions detection with an accuracy as high as 96.21%. Compared with existing state-of-the-art technology, the proposed model has improved the accuracy by more than 5%. The proposed model has successfully improved the automatic diagnosis of apical lesions. With the help of automation, dentists can focus more on technical and medical diagnoses, such as treatment, tooth cleaning, or medical communication. This proposal has been certified by the Institutional Review Board (IRB) with the certification number 202002030B0.

[6-(4-Bromo-phen-yl)-2,2'-bipyridine-κN,N']bis-(triphenyl-phosphane-κP)copper(I) tetra-fluoridoborate.

The title compound, [Cu(C(16)H(11)BrN(2))(C(18)H(15)P)(2)]BF(4), is composed of one Cu(I) atom, one 6-(4-bromo-phen-yl)-2,2'-bipyridine (L) ligand, two triphenyl-phosphane mol-ecules and one tetra-fluoridoborate anion. The Cu(I) ion is four-coordinated in a distorted tetra-hedral configuration by two N atoms from L and two P atoms from triphenyl-phosphane ligands. In the L ligand, the two pyridine rings are not coplanar; the mean planes making a dihedral angle of 15.3 (5)°. In the crystal, the ions are linked by weak C-H⋯F inter-actions.

Toxic mechanisms of Roth801, Canals, microparticles and nanoparticles of ZnO on MG-63 osteoblasts.

ZnO eugenol-based materials are widely used for restoration of caries cavity, apical retrograde filling and root canal sealer. Their effects on apical bone healing await investigation. The toxic mechanisms of ZnO particles and nanoparticles to MG-63 osteoblastic cells were studied. We found the different morphology and size of various particles as observed by scanning electron microscope. Particles of Canals and Roth801 were larger than ZnO-205532 microparticles and ZnO-677450 nanoparticles. Four ZnO particles showed cytotoxicity (>25 µg/ml) as analyzed by MTT. Transmission electron microscope found intracellular vacuoles with particle content. Exposure to ZnO particles induced ROS production and cell cycle arrest as studied by DCF and propidium iodide flow cytometry. ZnO particles activated ATM, ATR, Chk1, Chk2, γ-H2AX, ERK and p38 phosphorylation as detected by immunofluorescent staining and western blotting. The protein expression of cdc2, cyclin B1 and cdc25C were decreased, whereas GADD45α and hemeoxygenase-1 (HO-1) were stimulated. ZnO particles' cytotoxicity to MG63 cells was prevented by N-acetylcysteine (NAC), but not CGK733, AZD7762, U0126 and SB203580. ZnO showed little effect on IL-8 and sICAM-1 secretion. These results indicated that ZnO particles are toxic to osteoblasts. ZnO particles' toxicity were related to ROS, and DNA damage responses, checkpoint kinases, cell cycle arrest, ERK and p38 signaling, but not IL-8 and ICAM-1. These results were useful for materials' development and promote apical healing. Dentists should avoid of extruding ZnO-based sealers excessively over root apex and prevent residual ZnO-based retrograde filling materials in apical area during endodontic practice.

Sulfur-doped g-C3N4 nanosheets for photocatalysis: Z-scheme water splitting and decreased biofouling.

In this study, an S-doped g-C3N4 nanosheet was prepared as a photocatalyst for effective oxygen evolution reaction. Sulfur plays a crucial role in S-doped g-C3N4 not only in increasing the charge density but also in reducing the energy band gap of S-doped g-C3N4 via substitution of nitrogen sites. S-doped g-C3N4 can serve as an oxygen-evolved photocatalyst, when combined with Ru/SrTiO3:Rh in the presence of [Co(bpy)3]3+/2+ as an electron mediator, enables photocatalytic overall water splitting under visible light irradiation with hydrogen and oxygen production rates of 24.6 and 14.5 µmol-h-1, respectively. Moreover, the photocatalytic overall water splitting to produce H2 and O2 using this Z-scheme system could use for five runs to at least 94.5 h under visible light irradiation. On the other hand, S-doped g-C3N4 can reduce biofouling by bacteria such as Escherichia coli by more than 70%, by simply incubating the S-doped g-C3N4 sample with bacterial solution under light irradiation. Our results suggest that S-doped g-C3N4 is a potentially effective, green, and promising material for a variety of photocatalytic applications.

Recent Developments in Graphitic Carbon Nitride Based Hydrogels as Photocatalysts.

Solar-driven photocatalysis with graphitic carbon nitride (g-C3 N4 ) is considered to be the most promising approach for the generation of H2 from water, the degradation of organic pollutants, and the reduction of CO2 . However, bulk g-C3 N4 exhibits several drawbacks, such as a low specific surface area, high defect density, and fast charge recombination, which result in low photocatalytic performance. The construction of 3D porous hydrogels for g-C3 N4 through nanostructural engineering is a rapid, feasible, and cost-effective technique to improve the adsorption capability, stability, and separability of the hydrogel composite; to increase the number of active sites; and to create an internal conductive path for facile charge transfer and high photocatalytic activity. This minireview summarizes recent progress in photocatalytic water splitting and dye degradation by using g-C3 N4 -based hydrogels, with respect to state-of-the-art methods for synthesis, preparation, modification, and multicomponent coupling. Furthermore, comprehensive outlooks, future challenges, and concluding remarks regarding the use of g-C3 N4 -based hydrogels as highly efficient photocatalysts are presented.

Photocatalytic Dye and Cr(VI) Degradation Using a Metal-Free Polymeric g-C3N4 Synthesized from Solvent-Treated Urea.

The development of visible-light-driven polymeric g-C3N4 is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C3N4 from urea treated with various solvents such as methanol, ethanol, and ethylene glycol. The samples were characterized and the Williamson⁻Hall method was applied to investigate the lattice strain of the samples. The activity of the samples was evaluated by observing the degradation of methyl orange and K2Cr2O7 solution under light irradiation. Photocatalytic reaction kinetics were determined as pseudo-first-order and zero-order for the degradation of methyl orange and reduction of hexavalent chromium, respectively. Due to the inhibited charge separation resulting from the small lattice strain, reduced crystal imperfection, and sheet-like structure, g-C3N4 obtained from ethanol-treated urea exhibited the highest activity among the evaluated samples.