Ph Dependent
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2021 ◽  
Tobias Binninger ◽  
Adrian Heinritz ◽  
Rhiyaad Mohamed

The ideal gas reference for association and dissociation reactions, developed in the first part of this series, is applied to electrochemical reactions. We obtain an ideal Nernst equation that quantifies the unspecific voltage contribution arising from an imbalance between the reactant and product concentrations of an electrochemical reaction for the given conditions. Subtracting this concentration bias from the equilibrium voltage/potential, we define the "kinetic reference voltage/potential" where the reactant and product states are "aligned" within the potential energy landscape of the system. The kinetic reference voltage/potential is a fundamental descriptor for a given electrochemical reaction, providing an intrinsic reference point which is most relevant in cases where the (standard) equilibrium voltage/potential is biased by large concentration differences between the reactant and product side. This is most dramatic for the case of water electrolysis, where the gaseous H<sub>2</sub> and O<sub>2</sub> product concentrations are several orders of magnitude smaller than the liquid water reactant concentration. The respective equilibrium voltage is strongly biased by the low H<sub>2</sub> and O<sub>2</sub> concentrations, although the latter do not directly influence the forward water splitting rate. The unbiased kinetic reference voltage agrees remarkably well with the experimentally observed onset of macroscopic water splitting rates. We further extend our analysis to the kinetic reference potentials of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and lattice oxygen evolution reaction (LOER), providing an unconventional perspective on pH-dependent overpotentials, anticipated electrocatalysis improvements, and kinetic stabilization of electrocatalyst materials.

Radhini Veerappan ◽  
Aliscia Daniels ◽  
Moganavelli Singh

Nanotechnology is a favorable avenue for improving therapeutic strategies, especially in cancer therapy. The harmful side effects of traditional cancer therapy impact dramatically on the patient’s quality of life. Cisplatin, a commonly used anticancer drug, is implicated in side effects such as neurotoxicity, nephrotoxicity and reduced blood cell count. Silver nanoparticles (AgNPs) have been investigated for their antibacterial effects and their anticancer activities to a lesser extent. Their capability as drug delivery vehicles has not been fully exploited, primarily due to their inconclusive cytotoxicity observed in healthy tissues. This study aimed to synthesize and characterize nanoparticles (NPs), consisting of Ag, chitosan (Cs) and folic acid (FA) (CsAg and FACsAg), loading them with cisplatin (C) (C-CsAg and C-FACsAg) and comparing their anticancer activities in the human embryonic kidney (HEK293), breast adenocarcinoma (MCF-7) and cervical carcinoma (HeLa) cells. All NPs and drug nanocomplexes were morphologically and physicochemically characterized, revealing NPs and nanocomplexes of favorable sizes ([Formula: see text][Formula: see text]nm), polydispersity and stability. The drug encapsulation efficiencies for C-CsAg and C-FACsAg were 50% and 72%, respectively, while drug release studies indicated that cisplatin release was pH dependent. The C-FACsAg nanocomplexes produced greater anticancer activity than C-CsAg. Folate receptor-mediated uptake was confirmed for the C-FACsAg nanocomplexes in the receptor-rich HeLa cells boding well for future in vivo research.

BioChem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 148-158
Naoki Wada ◽  
Seiichi Matsugo

α-Lipoic acid (LA) has the specific absorption band at 330 nm and is quite vulnerable to UV irradiation, affording a variety of compounds including polymeric materials and hydrogen sulfide. A better understanding of the photochemical reaction of LA has already been carried out focusing mainly on the reaction product analysis derived from LA. We re-investigated the photochemical reaction of LA focusing our attention on the fate of hydrogen sulfide (H2S) produced in the photochemical reaction procedure. The photoirradiation of LA in the presence of oxidized glutathione (GSSG) formed glutathione trisulfide (GSSSG) and a reduced form of glutathione (GSH). Similar results were obtained in the co-presence of cystine and dimethyl disulfide. The concentration of H2S was reaching the maximum concentration, which was gradually decreasing within 10 min after photoirradiation, while the concentration of GSSSG was increasing with the decrease of H2S concentration. The structural confirmation of GSSSG and the plausible mechanism for the formation of GSSSG are proposed based on the time-dependent and pH-dependent profile of the photoirradiation.

Zhengheng Yang ◽  
Jinxing Ma ◽  
Fang Liu ◽  
Hailong Zhang ◽  
Xiaoming Ma ◽  

2021 ◽  
Vol 7 (4) ◽  
pp. 69
Georgios Asimakopoulos ◽  
Angeliki Karakassides ◽  
Maria Baikousi ◽  
Christina Gioti ◽  
Dimitrios Moschovas ◽  

Sodium polyacrylate is the superabsorbent waterlock polymer used in disposable diapers, which are the third largest single consumer item in landfills. As diapers are difficult to recycle, their use produces an incredible amount of environmental waste. In the present article, we present a reliable and facile approach to transform sodium polyacrylate, the main constitute in the used diapers, in a carbon-based magnetic sorbent material, capable for use in environmental applications. A nanoporous carbon magnetic hybrid material was prepared by reacting NaPA with iron acetate species under chemical activation conditions. Analysis of the characterization results revealed, the creation of a nanoporous structure, with high specific surface area value (SgBET = 611 m2/g), along with the formation of nanosized zero valent iron nanoparticles and iron carbide (Fe3C), inside the carbon pore system. 57Fe Mössbauer spectroscopy verified also the existence of these two main iron-bearing phases, as well as additional minor magnetic phases, such as Fe3O4 and γ-Fe2O3. Vibrating sample magnetometry (VSM) measurements of the obtained hybrid confirmed its ferromagnetic/ferrimagnetic behavior. The hybrid material demonstrated a rapid sorption of Cr(VI) ions (adsorption capacity: 90 mg/g, 24 h pH = 3). The results showed highly pH-dependent sorption efficiency of the hybrids, whereas a pseudo-second-order kinetic model described their kinetics.

2021 ◽  
Vol 9 ◽  
Bo Peng ◽  
Liu-Xi Zheng ◽  
Pan-Yue Wang ◽  
Jia-Feng Zhou ◽  
Meng Ding ◽  

On the origin of photoluminescence of noble metal NCs, there are always hot debates: metal-centered quantum-size confinement effect VS ligand-centered surface state mechanism. Herein, we provided solid evidence that structural water molecules (SWs) confined in the nanocavity formed by surface-protective-ligand packing on the metal NCs are the real luminescent emitters of Au-Ag bimetal NCs. The Ag cation mediated Au-Ag bimetal NCs exhibit the unique pH-dependent dual-emission characteristic with larger Stokes shift up to 200 nm, which could be used as potential ratiometric nanosensors for pH detection. Our results provide a completely new insight on the understanding of the origin of photoluminescence of metal NCs, which elucidates the abnormal PL emission phenomena, including solvent effect, pH-dependent behavior, surface ligand effect, multiple emitter centers, and large-Stoke’s shift.

2021 ◽  
pp. 2101618
Ning Zhao ◽  
Fei‐Er Yang ◽  
Cong‐Ying Zhao ◽  
Shi‐Wen Lv ◽  
Jin Wang ◽  

Xiaoxiao Hu ◽  
Qiang Zhang ◽  
Xiaomei Dai ◽  
Junyong Sun ◽  
Feng Gao

Langmuir ◽  
2021 ◽  
Tsung-Lin Hsieh ◽  
Stephen Law ◽  
Stephen Garoff ◽  
Robert D. Tilton

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