Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography

The chloride ion, Cl⁻, is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn₄Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl⁻ with a bromide ion (Br⁻) or an iodide ion (I⁻) in PSII and analyzed the crystal structures of PSII with Br⁻ and I⁻ substitutions. Substitution of Cl⁻ with Br⁻ did not inhibit oxygen evolution, whereas substitution of Cl⁻ with I⁻ completely inhibited oxygen evolution, indicating the efficient replacement of Cl⁻ by I⁻. PSII with Br⁻ and I⁻ substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn₄Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn₄Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl⁻ anions are required to maintain the coordination structure of the Mn₄Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active.     

Construction of TiO2-Eggshell for Efficient Degradation of Tetracycline Hydrochloride: Sunlight Induced In-Situ Formation of Carbonate Radical

Photocatalytic degradation of an antibiotic by utilizing inexhaustible solar energy represents an ideal solution for tackling global environment issues. The target generation of active oxidative species is highly desirable for the photocatalytic pollutants degradation. Herein, aiming at the molecular structure of tetracycline hydrochloride (TC), we construct sunlight-activated high-efficient catalysts of TiO₂-eggshell (TE). The composite ingeniously utilizes the photoactive function of TiO₂ and the composition of eggshell, which can produce oxidative ·CO₃⁻ species that are especially active for the degradation of aromatic compounds containing phenol or aniline structures. Through the synergistic oxidation of the··CO₃⁻ with the traditional holes (h⁺), superoxide radicals (·O²⁻) and hydroxyl radicals (·OH) involved in the photocatalytic process, the optimal TE photocatalyst degrades 92.0% TC in 30 min under solar light, which is higher than TiO₂ and eggshell. The photocatalytic degradation pathway of TC over TE has been proposed. The response surface methodology is processed by varying four independent parameters (TC concentration, pH, catalyst dosage and reaction time) on a Box–Behnken design (BBD) to optimize the experimental conditions. It is anticipated that the present work can facilitate the development of novel photocatalysts for selective oxidation based on ·CO₃⁻.     

An Improved Speciation Method Combining IC with ICPOES and Its Application to Iodide and Iodate Diffusion Behavior in Compacted Bentonite Clay

An accurate and effective method combining ion chromatography (IC) and inductively coupled plasma optical emission spectrometry (ICP-OES) was applied in this work to qualitatively and quantitatively analyze individual and co-existing iodide (I⁻) and iodate (IO₃⁻) at various concentrations. More specifically, a very strong linear relationship for the peak area for the co-existing I⁻ and IO₃⁻ ions was reached, and a high resolution value between two peaks was observed, which proves the effectiveness of our combined IC-ICP-OES method at analyzing iodine species. We observed lower accessible porosity for the diffusion of both I⁻ and IO₃⁻ in samples of bentonite clay using IC-ICP-OES detection methods, where the effective diffusion coefficient varied based on the anion exclusion effect and the size of the diffusing molecules. In fact, the distribution coefficients (K_d) of both I⁻ and IO₃⁻ were close to 0, which indicates that there was no adsorption on bentonite clay. This finding can be explained by the fact that no change in speciation took place during the diffusion of I⁻ and IO₃⁻ ions in bentonite clay. Our IC-ICP-OES method can be used to estimate the diffusion coefficients of various iodine species in natural environments.     

Laser Desorption/Ionization Mass Spectrometry as a Potential Tool for Evaluation of Hydroxylation Degree of Various Types of Titanium Dioxide Materials

For many applications, TiO₂ must have a unique surface structure responsible for its desirable physicochemical properties. Therefore the fast and easy methods of TiO₂ surface characterization are of great interest. Heated TiO₂ samples and dye-modified TiO₂ samples were analyzed by laser desorption/ionization mass spectrometry. In the negative ion mode, two types of ions were detected, namely (TiO₂)_n⁻ and (TiO₂)_nOH⁻. It has been established that the samples can be differentiated based on the relative ion abundances, especially with respect to the free hydroxyl group population. It indicates that laser desorption ionization mass spectrometry has the potential for the investigation of the surface properties of various TiO₂ materials.     

Facile Synthesis of g-C3N4/TiO2/Hectorite Z-Scheme Composite and Its Visible Photocatalytic Degradation of Rhodamine B

A novel g-C₃N₄/TiO₂/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti³⁺ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C₃N₄/TiO₂/hectorite was 0.01705 min⁻¹, which is approximately 5.38 and 4.88 times that of P25 and g-C₃N₄, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e⁻) and holes(h⁺). The F element from Hectorite causes the formation of Vo and Ti³⁺ in TiO₂, making it responsive to visible light. The effective separation of e⁻ and h⁺ mainly results from Z-scheme transfer of photo-produced electrons in g-C₃N₄/TiO₂ interface. The composites can be easily recycled and the degradation rate of the RhB still reached 84% after five cycles, indicating its good reusability.     

Electric Field Assisted Femtosecond Laser Preparation of Au@TiO2 Composites with Controlled Morphology and Crystallinity for Photocatalytic Degradation

TiO₂ is popular in photocatalytic degradation dye pollutants due to its abundance and its stability under photochemical conditions. Au loaded TiO₂ can achieve efficient absorption of visible light and deal with the problem of low conversion efficiency for solar energy of TiO₂. This work presents a new strategy to prepare Au nanoparticles-loaded TiO₂ composites through electric−field−assisted temporally−shaped femtosecond laser liquid-phase ablation of Au³⁺ and amorphous TiO₂. By adjusting the laser pulse delay and electric field parameters, gold nanoparticles with different structures can be obtained, such as nanospheres, nanoclusters, and nanostars (AuNSs). AuNSs can promote the local crystallization of amorphous TiO₂ in the preparation process and higher free electron density can also be excited to work together with the mixed crystalline phase, hindering the recombination between carriers and holes to achieve efficient photocatalytic degradation. The methylene blue can be effectively degraded by 86% within 30 min, and much higher than the 10% of Au nanoparticles loaded amorphous TiO₂. Moreover, the present study reveals the crystallization process and control methods for preparing nanoparticles by laser liquid ablation, providing a green and effective new method for the preparation of high-efficiency photocatalytic materials.     

Safety and Efficacy of the Moderate Sedation During Flexible Bronchoscopic Procedure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Moderate sedatives have been increasingly used to improve patient comfort during flexible bronchoscopy (FB). However, routine use of moderate sedation during FB is controversial because its efficacy and safety are not well established.This study aims to evaluate the efficacy and safety of moderate sedation during FB.A search was made of Medline, EMBASE, and the Cochrane Library to May 2014.Randomized controlled trials (RCTs) and quasi-RCTs were included.The main analysis was designed to examine the efficacy of moderate sedation during FB in sedation than no-sedation.The willingness to repeat FB was significantly more in sedation than no-sedation (odds ratio [OR] 2.30; 95% confidence interval [CI] 1.11–4.73; P = 0.02; I² = 22.5). The duration of FB was shorter in sedation group than no-sedation group (standardized mean difference [SMD] −0.21; 95% CI −0.38 to −0.03; P = 0.02; I² = 78.3%). Event of hypoxia was not significantly different between sedation and no-sedation groups (OR 0.86; 95% CI 0.42–1.73; P = 0.67; I² = 0%). The SpO₂ during procedure was not different between sedation and no-sedation groups (SMD −0.14; 95% CI −0.37 to 0.08; P = 0.21; I² = 49.9%). However, in subgroup analysis without supplemental oxygen, the SpO₂ was significantly lower in sedation than no-sedation group (SMD −0.45; 95% CI −0.78 to −0.11; P = 0.01; I² = 0.0%).According to this meta-analysis, moderate sedation in FB would be useful in patients who will require repeated bronchoscopies as well as safe in respiratory depression. To our knowledge, although the various sedative drugs are already used in the real field, this analysis was the first attempt to quantify objective results. We anticipate more definite and studies designed to elucidate standardized outcomes for moderate sedation in FB.     

Uterine FK506-binding protein 52 (FKBP52)–peroxiredoxin-6 (PRDX6) signaling protects pregnancy from overt oxidative stress

Immunophilin FK506-binding protein 52 (FKBP52) is a cochaperone that binds to the progesterone receptor (PR) to optimize progesterone (P₄)-PR signaling. We recently showed that Fkbp52-deficient (Fkbp52^−/−) mice have reduced uterine PR responsiveness and implantation failure which is rescued by excess P₄ supplementation in a genetic background-dependent manner. This finding led us to hypothesize that FKBP52 has functions in addition to optimizing PR activity. Using proteomics analysis, we found that uterine levels of peroxiredoxin-6 (PRDX6), a unique antioxidant, are significantly lower in Fkbp52^−/− mice than in WT and PR-null (Pgr^−/−) mice. We also found that Fkbp52^−/− mice with reduced uterine PRDX6 levels are susceptible to paraquat-induced oxidative stress (OS), leading to implantation failure even with P₄ supplementation. The same dose of paraquat did not interfere with implantation in WT mice. Moreover, treatment with antioxidants α-tocopherol and N-acetylcysteine (NAC) attenuated paraquat-induced implantation failure in P₄-treated Fkbp52^−/− mice. Functional analyses using mouse embryonic fibroblasts show that Fkbp52 deficiency associated with reduced PRDX6 levels promotes H₂O₂-induced cell death, which is reversed by the addition of NAC or by forced expression of PRDX6, suggesting that Fkbp52 deficiency diminishes the threshold against OS by reducing PRDX6 levels. These findings provide evidence that heightened uterine OS in Fkbp52^−/− females with reduced PRDX6 levels induces implantation failure even in the presence of excess P₄. This study shows that FKBP52–PRDX6 signaling protects pregnancy from overt OS.     

Dendritic Iron(III) Carbazole Complexes: Structural,Optical, and Magnetic Characteristics

This paper focuses on the synthesis, structural characterization, and study of the optical, magnetic, and thermal properties of novel architectures combining metal ions as magnetoactive centers and photoactive blocks formed by carbazole units. For this purpose, a series of azomethine complexes of the composition [Fe(L)₂]X (L = 3,6-bis[(3′,6′-di-tert-butyl-9-carbazol)-9-carbazol]benzoyloxy-4-salicylidene-N′-ethyl-N-ethylenediamine, X = NO₃⁻, Cl⁻, PF₆⁻) were synthesized by the reaction of metal salts with Schiff bases in a mixture of solvents. The UV–Vis absorption properties were studied in dichloromethane and rationalized via time-dependent density functional theory (DFT) calculations. Upon excitation at 350 nm, the compounds exhibited an intense dual fluorescence with two emission bands centered at ~445 and ~485 nm, which were assigned to π_carb–π* intraligand and π_carb–d_Fe ligand-to-metal charge-transfer excited states. EPR spectroscopy and SQUID magnetometry revealed solid-state partial spin crossover in some compounds, and antiferromagnetic interactions between the neighboring Fe(III) ions.     

Enhanced Photodegradation of p-Nitrobenzoic Acid by Binary Mixtures with Ba2+/TiO2 and MCM-41

A novel Ba(II)/TiO₂–MCM-41 composite was synthesized using binary mixtures with Ba²⁺/TiO₂ and MCM-41, and Ba²⁺ as a doping ion of TiO₂. The specific surface area and pore structure characterizations confirm that a mesoporous structure with a surface area of 341.2 m²/g and a narrow pore size distribution ranging from 2 to 4 nm was achieved using Ba(II)/TiO₂–MCM-41. Ba(II)/TiO₂ particles were synthesized into 10–15 nm particles and were well dispersed onto MCM-41. The diffraction peaks in the XRD patterns of TiO₂–MCM-41 and Ba(II)/TiO₂–MCM-41 were all attributed to anatase TiO₂. By taking advantage of MCM-41 and Ba²⁺, the photocatalytic performance of Ba(II)/TiO₂–MCM-41 was remarkably enhanced by suppressing its rutile phase, by lowering the band gap energy, and by facilitating the dispersion of TiO₂. Therefore, the photodegradation efficiencies of p-nitrobenzoic acid (4 × 10⁻⁴ mol/L) by various photocatalysts (60 min) under UV light irradiation are arranged in the following order: Ba(II)/TiO₂–MCM-41 (91.7%) > P25 (86.3%) > TiO₂–MCM-41 (80.6%) > Ba(II)/TiO₂ (55.7%) > TiO₂ (53.9%). The Ba(II)/TiO₂–MCM-41 composite was reused for five cycles and maintained a high catalytic activity (73%).     

High-Performance UV-Vis Light Induces Radical Photopolymerization Using Novel 2-Aminobenzothiazole-Based Photosensitizers

The popularity of using the photopolymerization reactions in various areas of science and technique is constantly gaining importance. Light-induced photopolymerization is the basic process for the production of various polymeric materials. The key role in the polymerization reaction is the photoinitiator. The huge demand for radical and cationic initiators results from the dynamic development of the medical sector, and the optoelectronic, paints, coatings, varnishes and adhesives industries. For this reason, we dealt with the subject of designing new, highly-efficient radical photoinitiators. This paper describes novel photoinitiating systems operating in UV-Vis light for radical polymerization of acrylates. The proposed photoinitiators are composed of squaraine (SQ) as a light absorber and various diphenyliodonium (Iod) salts as co-initiators. The kinetic parameters of radical polymerization of trimethylolpropane triacrylate (TMPTA), such as the degree of double bonds conversion (C_%), the rate of photopolymerization (R_p), as well as the photoinitiation index (I_p) were calculated. It was found that 2-aminobenzothiazole derivatives in the presence of iodonium salts effectively initiated the polymerization of TMPTA. The rates of polymerization were at about 2 × 10⁻² s⁻¹ and the degree of conversion of acrylate groups from 10% to 36% were observed. The values of the photoinitiating indexes for the most optimal initiator concentration, i.e., 5 × 10⁻³ M were in the range from 1 × 10⁻³ s⁻² even to above 9 × 10⁻³ s⁻². The photoinitiating efficiency of new radical initiators depends on the concentration and chemical structure of used photoinitiator. The role of squaraine-based photoinitiating systems as effective dyeing photoinitiators for radical polymerization is highlighted in this article.     

Ce Filling Limit and Its Influence on Thermoelectric Performance of Fe3CoSb12-Based Skutterudite Grown by a Temperature Gradient Zone Melting Method

CoSb₃-based skutterudite is a promising mid-temperature thermoelectric material. However, the high lattice thermal conductivity limits its further application. Filling is one of the most effective methods to reduce the lattice thermal conductivity. In this study, we investigate the Ce filling limit and its influence on thermoelectric properties of p-type Fe₃CoSb₁₂-based skutterudites grown by a temperature gradient zone melting (TGZM) method. Crystal structure and composition characterization suggests that a maximum filling fraction of Ce reaches 0.73 in a composition of Ce_0.73Fe_2.73Co_1.18Sb₁₂ prepared by the TGZM method. The Ce filling reduces the carrier concentration to 1.03 × 10²⁰ cm⁻³ in the Ce_1.25Fe₃CoSb₁₂, leading to an increased Seebeck coefficient. Density functional theory (DFT) calculation indicates that the Ce-filling introduces an impurity level near the Fermi level. Moreover, the rattling effect of the Ce fillers strengthens the short-wavelength phonon scattering and reduces the lattice thermal conductivity to 0.91 W m⁻¹ K⁻¹. These effects induce a maximum Seebeck coefficient of 168 μV K⁻¹ and a lowest κ of 1.52 W m⁻¹ K⁻¹ at 693 K in the Ce_1.25Fe₃CoSb₁₂, leading to a peak zT value of 0.65, which is 9 times higher than that of the unfilled Fe₃CoSb₁₂.     

Design an Epoxy Coating with TiO2/GO/PANI Nanocomposites for Enhancing Corrosion Resistance of Q235 Carbon Steel

In this work, a ternary TiO₂/Graphene oxide/Polyaniline (TiO₂/GO/PANI) nanocomposite was synthesized by in situ oxidation and use as a filler on epoxy resin (TiO₂/GO/PANI/EP), a bifunctional in situ protective coating has been developed and reinforced the Q235 carbon steel protection against corrosion. The structure and optical properties of the obtained composites are characterized by XRD, FTIR, and UV–vis. Compared to bare TiO₂ and bare Q235, the TiO₂/GO/PANI/EP coating exhibited prominent photoelectrochemical properties, such as the photocurrent density increased 0.06 A/cm² and the corrosion potential shifted from −651 mV to −851 mV, respectively. The results show that the TiO₂/GO/PANI nanocomposite has an extended light absorption range and the effective separation of electron-hole pairs improves the photoelectrochemical performance, and also provides cathodic protection to Q235 steel under dark conditions. The TiO₂/GO/PANI/EP coating can isolate the Q235 steel from the external corrosive environment, and may generally be regarded a useful protective barrier coating to metallic materials. When the TiO₂/GO/PANI composite is dispersed in the EP, the compactness of the coating is improved and the protective barrier effect is enhanced.     

Ablation of triadin causes loss of cardiac Ca2+ release units,impaired excitation–contraction coupling,and cardiac arrhythmias

Heart muscle excitation–contraction (E-C) coupling is governed by Ca²⁺ release units (CRUs) whereby Ca²⁺ influx via L-type Ca²⁺ channels (Cav1.2) triggers Ca²⁺ release from juxtaposed Ca²⁺ release channels (RyR2) located in junctional sarcoplasmic reticulum (jSR). Although studies suggest that the jSR protein triadin anchors cardiac calsequestrin (Casq2) to RyR2, its contribution to E-C coupling remains unclear. Here, we identify the role of triadin using mice with ablation of the Trdn gene (Trdn^−/−). The structure and protein composition of the cardiac CRU is significantly altered in Trdn^−/− hearts. jSR proteins (RyR2, Casq2, junctin, and junctophilin 1 and 2) are significantly reduced in Trdn^−/− hearts, whereas Cav1.2 and SERCA2a remain unchanged. Electron microscopy shows fragmentation and an overall 50% reduction in the contacts between jSR and T-tubules. Immunolabeling experiments show reduced colocalization of Cav1.2 with RyR2 and substantial Casq2 labeling outside of the jSR in Trdn^−/− myocytes. CRU function is impaired in Trdn^−/− myocytes, with reduced SR Ca²⁺ release and impaired negative feedback of SR Ca²⁺ release on Cav1.2 Ca²⁺ currents (I_Ca). Uninhibited Ca²⁺ influx via I_Ca likely contributes to Ca²⁺ overload and results in spontaneous SR Ca²⁺ releases upon β-adrenergic receptor stimulation with isoproterenol in Trdn^−/− myocytes, and ventricular arrhythmias in Trdn^−/− mice. We conclude that triadin is critically important for maintaining the structural and functional integrity of the cardiac CRU; triadin loss and the resulting alterations in CRU structure and protein composition impairs E-C coupling and renders hearts susceptible to ventricular arrhythmias.     

Fe–Doped TiO2–Carbonized Medium–Density Fiberboard for Photodegradation of Methylene Blue under Visible Light

Fe–doped titanium dioxide–carbonized medium–density fiberboard (Fe/TiO₂–cMDF) was evaluated for the photodegradation of methylene blue (MB) under a Blue (450 nm) light emitting diode (LED) module (6 W) and commercial LED (450 nm + 570 nm) bulbs (8 W, 12 W). Adsorption under daylight/dark conditions (three cycles each) and photodegradation (five cycles) were separately conducted. Photodegradation under Blue LED followed pseudo-second-order kinetics while photodegradation under commercial LED bulbs followed pseudo-first-order kinetics. Photodegradation rate constants were corrected by subtracting the adsorption rate constant except on the Blue LED experiment due to their difference in kinetics. For 8 W LED, the rate constants remained consistent at ~11.0 × 10⁻³/h. For 12 W LED, the rate constant for the first cycle was found to have the fastest photodegradation performance at 41.4 × 10⁻³/h. After the first cycle, the rate constants for the second to fifth cycle remained consistent at ~28.5 × 10⁻³/h. The energy supplied by Blue LED or commercial LEDs was sufficient for the bandgap energy requirement of Fe/TiO₂–cMDF at 2.60 eV. Consequently, Fe/TiO₂–cMDF was considered as a potential wood-based composite for the continuous treatment of dye wastewater under visible light.     

Photocatalytic Membrane Reactor for the Removal of C.I. Disperse Red 73

After the dyeing process, part of the dyes used to color textile materials are not fixed into the substrate and are discharged into wastewater as residual dyes. In this study, a heterogeneous photocatalytic process combined with microfiltration has been investigated for the removal of C.I. Disperse Red 73 from synthetic textile effluents. The titanium dioxide (TiO₂) Aeroxide P25 was selected as photocatalyst. The photocatalytic treatment achieved between 60% and 90% of dye degradation and up to 98% chemical oxygen demand (COD) removal. The influence of different parameters on photocatalytic degradation was studied: pH, initial photocatalyst loading, and dye concentration. The best conditions for dye degradation were pH 4, an initial dye concentration of 50 mg·L⁻¹, and a TiO₂ loading of 2 g·L⁻¹. The photocatalytic membrane treatment provided a high quality permeate, which can be reused.     

Counterion Effect and Isostructurality in a Series of Ag(I) Complexes Containing a Flexible,Imidazole Based Dipodal Ligand

The crystal structures of a series of Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene (L) and the counterions BF₄⁻ (1), PF₆⁻ (2), ClO₄⁻ (3), and CF₃SO₃⁻ (4) were analysed to determine the effect of the latter on their formation. All resulting compounds crystallise in the non-centrosymmetric space group Cc of a monoclinic system and show the formation of cationic, polymeric 1D Ag(I) complexes. SCXRD analyses revealed that compounds 1–3 are isostructural, though 1 shows opposite handedness compared to 2 and 3, resulting in an inversed packing arrangement. The presence of the larger, elongated triflate counterion in 4 leads to a different ligand conformation, as well as different arrangements of the ligand in the cationic chain, and simultaneously results in a packing that exhibits fewer similarities with the remaining three compounds.     

Influence of 3d Transition Metal Doping on Lithium Stabilized Na-β″-Alumina Solid Electrolytes

Na-β″-alumina is the commercially most successful solid electrolyte due to its application in ZEBRA and NAS^® batteries. In this work, Li-stabilized Na-β″-alumina electrolytes were doped with 3d transition metal oxides, namely TiO₂, Mn₃O₄, and NiO, in order to improve their ionic conductivity and fracture strength. Due to XRD and EDX measurements, it was concluded that Mn- and Ni-ions are incorporated into the crystal lattice of Na-β″-alumina. In contrast, TiO₂ doping results in the formation of secondary phases that enable liquid-assisted sintering at temperatures as low as 1500 °C. All dopants increased the characteristic fracture strength of the electrolytes; 1.5 wt% of NiO doping proved to be most efficient and led to a maximal characteristic fracture strength of 296 MPa. Regarding the ionic conductivity, TiO₂ doping showed the uppermost value of up to 0.30 S cm⁻¹ at 300 °C. In contrast to the other dopants, TiO₂ doping lowered the sintering temperature needed to obtain a dense, stable, and highly conductive Na-β″-alumina electrolyte suitable for applications in Na based batteries.     

Novel Triarylamine-Based Hole Transport Materials: Synthesis,Characterization and Computational Investigation

Three novel triarylamine-based electron-rich chromophores were synthesized and fully characterized. Compounds 1 and 2 were designed with electron-rich triphenylamine skeleton bearing two and four decyloxy groups namely, 3,4-bis(decyloxy)-N,N-diphenylaniline and N-(3,4-bis(decyloxy)phenyl)-3,4-bis(decyloxy)-N-phenylaniline, respectively. The well-known electron-rich phenothiazine was introduced to diphenylamine moiety through a thiazole ring to form N,N-bis(3,4-bis(decyloxy)phenyl)-5-(10H-phenothiazin-2-yl)thiazol-2-amine (Compound 3). These three novel compounds were fully characterized and their UV–vis absorption indicated their transparency as a favorable property for hole transport materials (HTMs) suitable for perovskite solar cells. Cyclic voltammetry measurements revealed that the HOMO energy levels were in the range 5.00–5.16 eV for all compounds, indicating their suitability with the HOMO energy level of the perovskite photosensitizer. Density functional theory (DFT) and time-dependent DFT (TD-DFT) have been used to investigate the possibility of the synthesized compounds to be utilized as HTMs for perovskite solar cells (PSCs). The computational investigation revealed that the hole mobility of Compound 1 was 1.08 × 10⁻² cm² V⁻¹ s⁻¹, and the substitution with two additional dialkoxy groups on the second phenyl ring as represented by Compound 2 significantly boosted the hole mobility to reach the value 4.21 × 10⁻² cm² V⁻¹ s⁻¹. On the other hand, Compound 3, in which the third phenyl group was replaced by a thiazole-based phenothiazine, the value of hole mobility decreased to reach 5.93 × 10⁻⁵ cm² V⁻¹ s⁻¹. The overall results indicate that these three novel compounds could be promising HTMs for perovskite solar cells.     

A transient outward-rectifying K+ channel current down-regulated by cytosolic Ca2+ in Arabidopsis thaliana guard cells

Sustained (noninactivating) outward-rectifying K⁺ channel currents have been identified in a variety of plant cell types and species. Here, in Arabidopsis thaliana guard cells, in addition to these sustained K⁺ currents, an inactivating outward-rectifying K⁺ current was characterized (plant A-type current: I_AP). I_AP activated rapidly with a time constant of 165 ms and inactivated slowly with a time constant of 7.2 sec at +40 mV. I_AP was enhanced by increasing the duration (from 0 to 20 sec) and degree (from +20 to −100 mV) of prepulse hyperpolarization. Ionic substitution and relaxation (tail) current recordings showed that outward I_AP was mainly carried by K⁺ ions. In contrast to the sustained outward-rectifying K⁺ currents, cytosolic alkaline pH was found to inhibit I_AP and extracellular K⁺ was required for I_AP activity. Furthermore, increasing cytosolic free Ca²⁺ in the physiological range strongly inhibited I_AP activity with a half inhibitory concentration of ≈ 94 nM. We present a detailed characterization of an inactivating K⁺ current in a higher plant cell. Regulation of I_AP by diverse factors including membrane potential, cytosolic Ca²⁺ and pH, and extracellular K⁺ and Ca²⁺ implies that the inactivating I_AP described here may have important functions during transient depolarizations found in guard cells, and in integrated signal transduction processes during stomatal movements.