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In this study, we propose an eco-friendly method for synthesizing cerium tungstate nanoparticles using hydrothermal techniques. We used scanning, transmission electron microscopy, and X-ray diffraction to analyze the morphology of the synthesized nanoparticles. The results showed that the synthesized nanoparticles were uniform and highly crystalline, with a particle size of about 50 nm. The electrocatalytic properties of the nanoparticles were then investigated using cyclic voltammetry and electrochemical impedance spectroscopy. We further used the synthesized nanoparticles to develop an electrochemical sensor based on a carbon paste electrode that can detect hydroquinone. By optimizing the differential pulse voltammetric method, a wide linearity range of 0.4 to 45 µM and a low detection limit of 0.06 µM were obtained. The developed sensor also expressed excellent repeatability (RSD up to 3.8%) and reproducibility (RSD below 5%). Interferences had an insignificant impact on the determination of analytes, making it possible to use this method for monitoring hydroquinone concentrations in tap water. This study introduces a new approach to the chemistry of materials and the environment and demonstrates that a careful selection of components can lead to new horizons in analytical chemistry.

A kinetic model derived from a simplified reaction sequence is proposed for the photo-Fenton degradation of Paracetamol (PCT), employing an annular photoreactor. The kinetic model explicitly included the effects of radiation absorption on pollutant degradation kinetics through the evaluation of the Local Volumetric Rate of Photon Absorption (LVRPA). Irradiated experiments achieved an average PCT conversion of 99.3% at 5 min of reaction, and a maximum of 69% of mineralization. Conversely, non-irradiated experiments reached an average PCT conversion of 86.6% at 5 min of reaction, and a maximum of 35% of mineralization. Kinetic parameters (, ,M-1s-1) were estimated employing a nonlinear, multi-parameter regression method, and the validated kinetic model was used to predict temporal variations of the concentrations of HP, PCT, and the main reaction intermediates: hydroquinone (HQ) and 1,4-benzoquinone (BQ). The root mean square error (RMSE) values obtained for HP, PCT, HP, HQ and BQ were 1.16¿×¿10-2, 7.13¿×¿10-1, 3.53¿×¿10-3, 3.05¿×¿10-3 mM, respectively, showing a good agreement between experimental and predicted data. Moreover, the kinetic model was validated with a new set of experimental tests, confirming its predictive capacity. Beyond the degree of mineralization attained, additional cytotoxicity tests proved that the photo-Fenton process is effective in generating a non-toxic effluent under the operating variables investigated., Peer Reviewed, Postprint (published version)

Hydroquinone, Mercury (Hg), and Arsenic (As) are hazardous to health upon long-term exposure. Hydroquinone, Hg, and As were analysed in skin-lightening cosmetics randomly purchased from different cosmetic outlets within the Ilorin metropolis, Nigeria. The amount of hydroquinone in the samples was determined using a UV-spectrophotometry method at 290 nm. Hg and As were quantified using atomic absorption spectrophotometry (AAS). UV-spectrophotometry method validation showed excellent linearity (r2 = 0.9993), with limits of detection (0.75 g/mL), limits of quantification (2.28 g/mL), relative standard deviation (0.01–0.35%), and recovery (95.85–103.56%) in the concentration range of 5–50 g/mL. Similarly, r2, LOD, and LOQ for Hg and As were 0.9983 and 0.9991, (0.5 and 1.0 g/L) and 1.65 and 3.3 g/L) respectively. All the samples contained hydroquinone, Hg and As in varying amounts. The amounts of hydroquinone, Hg and As present were in the ranges of 1.9–3.3%, 0.08–2.52 g/g and 0.07–5.30 g/g respectively. Only three of the analysed samples contained hydroquinone within the permissible limit of 2.0% w/w in cosmetic products. All the samples analysed contained mercury and arsenic in varying amounts. The need to periodically monitor the levels of hydroquinone, mercury, and arsenic in skin-lightening cosmetics marketed in Nigeria is recommended.

Background: Melasma is a hyperpigmentation disorder that affects the quality of life, especially in women. Hydroquinone has remained the mainstay of melasma treatment. However, its safety for long-term usage became a great concern. Combination therapy, such as niacinamide and kojic acid, can be used as an alternative melasma treatment due to different mechanisms of action and synergism. Purpose: The aim of this study was to compare the efficacy and safety of a combination of 4% niacinamide and 4% kojic acid (N-K) vs. 4% hydroquinone (HQ) in epidermal melasma. Methods: This was a randomized, double blind, clinical study on 13 female epidermal melasma patients at the Cosmetic Dermatology Outpatient Clinic of Dr. Hasan Sadikin Hospital, Bandung. Patients received two creams, a combination of N-K and HQ, for split-face therapy, regardless of the sides of the face. All patients were followed up at 4 and 8 weeks. The clinical efficacy was assessed for skin lightening effects using a spectrophotometer (L* value) and the melasma area severity index (MASI). Adverse effects were assessed in all patients. Result: Both the N-K and HQ groups showed significant improvement in skin lightening and MASI scores on week 8 (p <0.05). There was no statistically significant difference in efficacy between the N-K and HQ groups (p >0.05). None of the patients in the N-K group complained of any adverse effects. Whereas in the HQ group, 23.07% presented with pruritus and mild erythema.

Background: Melasma is a hyperpigmentation disorder that affects the quality of life, especially in women. Hydroquinone has remained the mainstay of melasma treatment. However, its safety for long-term usage became a great concern. Combination therapy, such as niacinamide and kojic acid, can be used as an alternative melasma treatment due to different mechanisms of action and synergism. Purpose: The aim of this study was to compare the efficacy and safety of a combination of 4% niacinamide and 4% kojic acid (N-K) vs. 4% hydroquinone (HQ) in epidermal melasma. Methods: This was a randomized, double blind, clinical study on 13 female epidermal melasma patients at the Cosmetic Dermatology Outpatient Clinic of Dr. Hasan Sadikin Hospital, Bandung. Patients received two creams, a combination of N-K and HQ, for split-face therapy, regardless of the sides of the face. All patients were followed up at 4 and 8 weeks. The clinical efficacy was assessed for skin lightening effects using a spectrophotometer (L* value) and the melasma area severity index (MASI). Adverse effects were assessed in all patients. Result: Both the N-K and HQ groups showed significant improvement in skin lightening and MASI scores on week 8 (p <0.05). There was no statistically significant difference in efficacy between the N-K and HQ groups (p >0.05). None of the patients in the N-K group complained of any adverse effects. Whereas in the HQ group, 23.07% presented with pruritus and mild erythema.

A facile strategy to modify the surface of K2SiF6:Mn4+ (KSFM) with commercially available hydrophilic hydroquinone (HQ) has been developed and waterproof stability (moisture resistance) of the KSFM has been significantly improved. It has been demonstrated that there are strong interactions between KSFM and HQ on the interface due to the hydrogen bonds of fluorine in KSFM with hydrogen in HQ. The relative luminous intensity of HQ-modified KSFM (denoted as KSFM-HQ) remained 99.7% of its initial value after immersion in water for 336 h, remarkable higher than that of KSFM which remained only 38.0%. It is proposed that the high water resistance of KSFM-HQ is achieved via two possible mechanisms: in situ decomposition of dark brown manganese (owing to the hydrolysis of [MnF6]2−) on the KSFM crystal surface and consequently the formation of a more protective Mn4+-free layer. The process effectively combines the advantages of transparent organic materials (herein HQ) before immersion in water and durable moisture resistance of inorganic materials (herein K2SiF6) on surface after immersion in water. The importance of HQ loading on moisture-sensitive fluoride phosphors has been further confirmed by using HQ-treated K2GeF6:Mn4+ (KGFM) as an additional example. This strategy provides a one-of-a-kind way to the development of water-resistant Mn4+-doped fluoride phosphors with high luminous stability for potential applications in water-borne fluorescent anti-counterfeiting ink and even warm WLEDs operating in high humidity. © 2023

Hydroquinone clathrates have been proposed as potential gas separation and storage media. Experimental results have demonstrated enhanced preferential adsorption for certain guest molecules, and also stability over temperature and pressure ranges that make them promising candidates to be employed in applications as hydrogen storage. Despite this, the characterization of these inclusion solids from thermodynamic and kinetic perspectives is still poor. In this work, we have tried to estimate the hydrogen storage ability of these clathrates using molecular simulations. The process of diffusion of hydrogen guest molecules from an external reservoir has been simulated using molecular dynamics, and the thermodynamic occupancy limit at different (T,p) conditions has been computed using hydrid Grand-Canonical Monte Carlo/Molecular Dynamics. The results show that hydrogen diffusion from an external reservoir is limited by interfacial phenomena in the clathrate surface, and also that multiple guest occupancy and its distribution can be computed using the described approach

We have used for the first time a conjugated redox polymer with hydroquinone (HQ) pendant groups covalently attached to the poly(3,4-ethylenedioxythiophene) (PEDOT) backbone as the solid contact (SC) in plasticized poly(vinyl chloride) (PVC) based K+-selective electrodes (K-SCISE). Redox couples are one of the simplest ways to precisely adjust the standard potential (E°) of the SCISEs, but usually the initially high E° reproducibility is lost quite quickly due to leaching out of non-covalently bound redox molecules from the SCISE. In PEDOT-HQ, the covalently attached HQ groups prevent the leaching and simultaneously allow additional charge storage in PEDOT-HQ that is ca. 25–30 times higher than for unsubstituted PEDOT. Before the ion-selective membrane (ISM) deposition, we controlled the potential of the SC with high reproducibility (±0.4 mV, n = 5) by pre-polarization in a mixture of acetonitrile containing potassium tetrakis(pentafluorophenyl)borate and perchloric acid as proton source. Pre-polarization of the SC close to the formal potential where the redox buffer capacity is highest gave the best potential reproducibility. However, after the ISM deposition, the K-SCISEs showed in the best case an E° reproducibility of ±2.8 mV (n = 5). Chronopotentiometric measurements reveal that only a minor fraction of the very high redox capacitance of PEDOT-HQ can be utilized for the ion-to-electron transduction beneath the ISM. The influence of this shortcoming on the E° reproducibility of the SCISEs has been underestimated for most SC materials. Modification of the commonly used PVC-ISM formulations to allow faster ion transfer at the SC/ISM interface could be one way of overcoming the disadvantage.

Background: Melasma is an acquired cutaneous disorder characterised by prominent hyperpigmentation which presents with brown macules or patches on photo-exposed areas. Current first-line treatments for melasma include non-pharmacological measures as photoprotection, cosmetic camouflage and topical therapies such as hydroquinone. 1 Although hydroquinone remains as the gold standard treatment for melasma, its actions are limited by side effects and potential relapses.1 More recently cysteamine cream has been trialled as an alternative therapy for melasma and an early trial has shown benefits compared to placebo.2 There have been no direct comparisons between cysteamine cream and hydroquinone cream. Objective(s): Our study aims to determine the efficacy of cysteamine cream compared to hydroquinone cream in the treatment of melasma. Method(s): Female patients, 18 years and older, with at least three months history of moderate to severe melasma and satisfied the exclusion criteria were included in the study. Patients were randomised to the two study arms; the control was advised to apply hydroquinone daily for 16 weeks and the treatment group was advised to apply cysteamine cream daily for 16 weeks. Both groups were advised on regular sunscreen application. The primary endpoint measurement was the modified Melasma Area and Severity Index (mMASI) score. Result(s): 20 patients have satisfied the inclusion/exclusion criteria and are enrolled in the study. Results to be updated prior to the conference. Conclusion(s): This randomised control study will evaluate the efficacy of cysteamine cream for the treatment of melasma and whether it may be superior compared to the current gold standard treatment hydroquinone.

We propose a simple method of improving the hole injection in the quantum rod light-emitting diode (QRLED) device by doping hydroquinone (HQ) into the PEDOT:PSS HIL. The turn-on voltage and the EQE of QRLEDs improved from 2.8 to 2.3 V and from 6.5 to 9.5%. © 2021 IEEE.

Background: Melasma is an acquired cutaneous disorder characterised by prominent hyperpigmentation which presents with brown macules or patches on photo-exposed areas. Current first-line treatments for melasma include non-pharmacological measures as photoprotection, cosmetic camouflage and topical therapies such as hydroquinone. 1 Although hydroquinone remains as the gold standard treatment for melasma, its actions are limited by side effects and potential relapses.1 More recently cysteamine cream has been trialled as an alternative therapy for melasma and an early trial has shown benefits compared to placebo.2 There have been no direct comparisons between cysteamine cream and hydroquinone cream. Objective(s): Our study aims to determine the efficacy of cysteamine cream compared to hydroquinone cream in the treatment of melasma. Method(s): Female patients, 18 years and older, with at least three months history of moderate to severe melasma and satisfied the exclusion criteria were included in the study. Patients were randomised to the two study arms; the control was advised to apply hydroquinone daily for 16 weeks and the treatment group was advised to apply cysteamine cream daily for 16 weeks. Both groups were advised on regular sunscreen application. The primary endpoint measurement was the modified Melasma Area and Severity Index (mMASI) score. Result(s): 20 patients have satisfied the inclusion/exclusion criteria and are enrolled in the study. Results to be updated prior to the conference. Conclusion(s): This randomised control study will evaluate the efficacy of cysteamine cream for the treatment of melasma and whether it may be superior compared to the current gold standard treatment hydroquinone.

Background: Melasma is an acquired cutaneous disorder characterised by hyperpigmentation which presents with brown macules or patches on photo-exposed areas. Current first-line treatments for melasma include non-pharmacological measures such as photoprotection, cosmetic camouflage and topical therapies including hydroquinone. Although hydroquinone remains the gold standard treatment for melasma, its actions are sometimes limited by side effects and potential relapses. Recently 5% cysteamine cream has been trialled as an alternative therapy for melasma and an early trial has shown benefits compared to placebo. There have been no direct comparisons between cysteamine cream and hydroquinone cream to date. Objective(s): Our study aims to determine the efficacy of cysteamine cream compared to hydroquinone cream in the treatment of melasma. Method(s): Female patients, 18 years and older, with at least three months history of moderate to severe melasma and satisfied the exclusion criteria were included in the study. Patients were randomised to the two study arms; the control was applied 4% hydroquinone cream daily for 16 weeks and the treatment group applied 5% cysteamine cream daily for 16 weeks. Both groups were advised to apply sunscreen daily with re-application during the day. The primary endpoint measurement was the modified Melasma Area and Severity Index (mMASI) score. Result(s): 20 patients satisfied the inclusion/exclusion criteria and are enrolled in the study. Results to be updated prior to the conference. Conclusion(s): This randomised control study will evaluate the efficacy of cysteamine cream for the treatment of melasma and whether it may be superior compared to the current gold standard treatment hydroquinone.

Severe drawbacks associated with the topical use of depigmenting agents in treatments of skin hyperigmentations impose a great demand for novel, effective, and safe melanogenesis inhibitors. Edible and medicinal mushrooms, known for numerous health-promoting properties, represent a rich reservoir of anti-melanogenic compounds, with the potential to be applied in preventing excessive skin pigmentation. Herein, using zebrafish (Danio rerio) as a preclinical animal model, we have demonstrated that ethanol extract of Laetiporus sulphureus (LSE) and Agaricus silvaticus (ASE) are not toxic at high doses up to 400-500 mu g/mL while effectively inhibit melanogenesis in a dose-dependent manner. At depigmenting doses, the explored extracts showed no adverse effects on zebrafish embryos melanocytes. Even more, they did not provoke inflammation or neutropenia when applied at the highest dose ensuring almost complete the cells depigmentation. Since LSE and ASE have demonstrated significantly higher the therapeutic potential than kojic acid and hydroquinone, two well-known depigmenting agents, overall results of this study strongly suggest that the explored mushrooms extracts could be used as efficient and safe topical agents in treatments of skin hyperpigmentation disorders.

We propose a simple method of improving the hole injection in the quantum rod light-emitting diode (QRLED) device by doping hydroquinone (HQ) into the PEDOT:PSS HIL. The turn-on voltage and the EQE of QRLEDs improved from 2.8 to 2.3 V and from 6.5 to 9.5%. © 2021 IEEE.

High-glass transition thermoplastic polymers have dawned much attention in recent years due to their typical stiffness, enhanced thermal properties, and more importantly the emerging need to replace commercial fossil-based products by more sustainable alternatives, derived from renewable resources. In this regard we engineer here for the first time the design of wholly (hetero-)aromatic polyesters based on a key-platform chemical-2,5-furandicarboxylic acid (FDCA) and commercially-available catechol, or hydroquinone, whose structures were characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR). Both polymers had a high glass transition (Tg up to 167 °C) detected by differential scanning calorimetry (DSC) and has excellent thermal stability according to thermogravimetric analysis (TGA). The para- and ortho- substitution in hydroquinone and catechol, respectively, affected crystallinity, which was typically higher for poly(1,4-phenylene-2,5-furandicarboxylate) (PHQF) favouring a stiffer and close packing structure. Also, the thermal properties were higher for PHQF.

[EN] Sustainable reduced graphene oxide (rGO) carbocatalysts for molecular oxygen activation have been developed based on the concept that chemical reduction of graphene oxide to rGO introduces functional groups that can become active sites. Thus, a series of rGOs prepared using hydroquinone (HQ), hydrazine (HZ) and ascorbic acid (ASC) as reducing agents have been tested as catalysts in the aerobic oxidations of thiophenol and indane. In both oxidation reactions, rGO reduced by HQ (rGO-HQ) exhibited the highest catalytic activity and stability. A high selectivity of of/one (90 %) at around 30 % indane conversion in the absence of transition metals was achieved. Reusability test showed that the activity of rGO-HQ is mostly retained in three consecutive runs. Quenching experiments indicated that the reaction proceeds with the generation of hydroxyl and carbon centered radicals. The higher activity of rGO-HQ was attributed to the covalent anchoring of some HQ molecules on rGO during the chemical reduction. This knowledge has been used to develop a HQ-functionalized Merrifield resin that in spite of its very different textural properties compared to rGO also exhibits catalytic activity for O-2 activation. The present work illustrates the potential to develop rGO carbocatalysts with an increased density of active sites by selecting an appropriate reducing agent during the chemical reduction of graphene oxide.

[EN] Sustainable reduced graphene oxide (rGO) carbocatalysts for molecular oxygen activation have been developed based on the concept that chemical reduction of graphene oxide to rGO introduces functional groups that can become active sites. Thus, a series of rGOs prepared using hydroquinone (HQ), hydrazine (HZ) and ascorbic acid (ASC) as reducing agents have been tested as catalysts in the aerobic oxidations of thiophenol and indane. In both oxidation reactions, rGO reduced by HQ (rGO-HQ) exhibited the highest catalytic activity and stability. A high selectivity of of/one (90 %) at around 30 % indane conversion in the absence of transition metals was achieved. Reusability test showed that the activity of rGO-HQ is mostly retained in three consecutive runs. Quenching experiments indicated that the reaction proceeds with the generation of hydroxyl and carbon centered radicals. The higher activity of rGO-HQ was attributed to the covalent anchoring of some HQ molecules on rGO during the chemical reduction. This knowledge has been used to develop a HQ-functionalized Merrifield resin that in spite of its very different textural properties compared to rGO also exhibits catalytic activity for O-2 activation. The present work illustrates the potential to develop rGO carbocatalysts with an increased density of active sites by selecting an appropriate reducing agent during the chemical reduction of graphene oxide.

Hydroquinone (HQ) is an anti-hyperpigmentation agent with poor physicochemical stability. HQ formulations are currently elaborated by compounding in local pharmacies. Variability in the characteristics of HQ topical formulations can lead to remarkable di_erences in terms of their stability, e_cacy, and toxicity. Four di_erent semisolid O/Wformulations with 5% HQ were prepared using: (i) Beeler´s base plus antioxidants (F1), (ii) Beeler´s base and dimethyl isosorbide (DMI) as solubiliser (F2), (iii) olive oil and DMI (F3), and (iv) Nourivan®, a skin-moisturising and antioxidant base, along with DMI (F4). Amongst the four formulations, F3 showed the greatest physicochemical stability with less tendency to coalescence but with marked chromatic aberrations. An inverse correlation was established by multivariate analysis between the mean droplet size in volume and the steady-state flux, which explains why F3, with the smallest droplet size and the most hydrophobic excipients, exhibited the highest permeation across both types of membranes with enhancement ratios of 2.26 and 5.67-fold across Strat-M® and mouse skin, respectively, compared to F1. It is crucial to understand how the HQ is formulated, bearing in mind that the use of di_erent excipients can tune the transdermal delivery of HQ significantly., Depto. de Farmacia Galénica y Tecnología Alimentaria, Fac. de Farmacia, TRUE, pub

Exogenous ochronosis (EO) is an entity that manifests as black-bluish or grayish-brown cutaneous hyperpigmentation, which is a consequence of the deposition of ochronotic pigment with characteristic banana-like morphology between the collagen fibers of the dermis. Both the clinical presentation and histopathology appearance are superimposable with endogenous ochronosis or alcaptonuria, a hereditary disease in which ochronotic pigment deposition occurs at a multisystemic level. The most frequent cause of EO is the use of facial depigmenting creams containing hydroquinone, a common practice among women with high phototypes. We present a woman who developed EO on the face, upper chest, and back after prolonged use of a depigmenting cream containing hydroquinone.

The electrochemistry of catecholamine neurotransmitters and their precursor l-dopa has been widely studied due to their relevance as biologically important compounds. The detection of these compounds from aqueous solution is hindered by the coexistence of quinone or hydroquinone. However, it was suggested that quinones adsorbed on the electrode surface can enhance catechol detection. In order to estimate the degree of interaction between quinones and l-dopa, cyclic voltammetry and UV-Vis spectroscopic study was performed. A sesquiterpenoid hydroquinone, isolated from the marine sponge Dysidea avara (avarol), has been used in this study. The change of apparent heterogeneous rate constant with different avarol/l-dopa ratio indicated that charge transfer could be enhanced at some extent. In addition to this, the obtained results for avarol and hydroquinone (its structural element) were compared. UV-Vis spectroscopic analysis confirmed interaction between l-dopa and avarol or hydroquinone. Taken all together, the interaction of l-dopa was stronger with hydroquinone than with avarol, presumably reflecting the conformational restrains of avarol caused by its terpenoid moiety.

Exogenous ochronosis (EO) is an entity that manifests as black-bluish or grayish-brown cutaneous hyperpigmentation, which is a consequence of the deposition of ochronotic pigment with characteristic banana-like morphology between the collagen fibers of the dermis. Both the clinical presentation and histopathology appearance are superimposable with endogenous ochronosis or alcaptonuria, a hereditary disease in which ochronotic pigment deposition occurs at a multisystemic level. The most frequent cause of EO is the use of facial depigmenting creams containing hydroquinone, a common practice among women with high phototypes. We present a woman who developed EO on the face, upper chest, and back after prolonged use of a depigmenting cream containing hydroquinone.

This dissertation describes a general synthetic platform for segmented polymers that have main-chain reversible linkages based on cyclopentadiene-maleimide Diels-Alder chemistry. Research in the area of thermally reversible (self-healing) polymers has been an ever-expanding area of interest in the current scientific literature. However most of the emphasis has been on systems containing furan-maleimide linkages. While inexpensive and synthetically accessible, furan chemistry is mostly limited to crosslinked and hyperbranched architectures due to its relatively weak binding with maleimides at suitable propagation temperatures. Following a general review of the literature in this area (Chapter 1) the first stage of our research (Chapter 2) entails the synthesis of 2-substituted hydroquinones, which are needed as monomers in the later stages. The novelty of our hydroquinone synthesis stems from the use of allylic and other alkenyl ethers as the source of the ring substituent, and from the utilization of catalytic hydroboration to improve atom-efficiency. We showed that hydroquinones with widely varying functionality can be prepared efficiently by our method; these findings were published in the journal Tetrahedron in 2018. The second stage (Chapter 3) involves the use of the new hydroquinones in step-growth syntheses of hydroquinone-terminated telechelic and chain-extension of these telomers via Diels-Alder chemistry to form segmented polymers having thermally reversible linkages. The novelty of our approach rests with the use of cyclopentadiene-maleimide chemistry for the linkages, while the overall physical properties such as the glass transition temperature were established by using well-defined aromatic polymers — poly(ether ether ketones) or PEEK and poly(aryl ether sulfones) or PAES — as segments. This approach represents an important departure from earlier work in our group in which reversible linkages were present in every repeat unit of a step-growth Diels-Ald

The electrochemistry of catecholamine neurotransmitters and their precursor l-dopa has been widely studied due to their relevance as biologically important compounds. The detection of these compounds from aqueous solution is hindered by the coexistence of quinone or hydroquinone. However, it was suggested that quinones adsorbed on the electrode surface can enhance catechol detection. In order to estimate the degree of interaction between quinones and l-dopa, cyclic voltammetry and UV-Vis spectroscopic study was performed. A sesquiterpenoid hydroquinone, isolated from the marine sponge Dysidea avara (avarol), has been used in this study. The change of apparent heterogeneous rate constant with different avarol/l-dopa ratio indicated that charge transfer could be enhanced at some extent. In addition to this, the obtained results for avarol and hydroquinone (its structural element) were compared. UV-Vis spectroscopic analysis confirmed interaction between l-dopa and avarol or hydroquinone. Taken all together, the interaction of l-dopa was stronger with hydroquinone than with avarol, presumably reflecting the conformational restrains of avarol caused by its terpenoid moiety.

The electrochemistry of catecholamine neurotransmitters and their precursor l-dopa has been widely studied due to their relevance as biologically important compounds. The detection of these compounds from aqueous solution is hindered by the coexistence of quinone or hydroquinone. However, it was suggested that quinones adsorbed on the electrode surface can enhance catechol detection. In order to estimate the degree of interaction between quinones and l-dopa, cyclic voltammetry and UV-Vis spectroscopic study was performed. A sesquiterpenoid hydroquinone, isolated from the marine sponge Dysidea avara (avarol), has been used in this study. The change of apparent heterogeneous rate constant with different avarol/l-dopa ratio indicated that charge transfer could be enhanced at some extent. In addition to this, the obtained results for avarol and hydroquinone (its structural element) were compared. UV-Vis spectroscopic analysis confirmed interaction between l-dopa and avarol or hydroquinone. Taken all together, the interaction of l-dopa was stronger with hydroquinone than with avarol, presumably reflecting the conformational restrains of avarol caused by its terpenoid moiety.

Producción Científica, Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)

Producción Científica, Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)

Substituted derivatives of hydroquinone/benzoquinone were studied as organic redox mediators in the electrolyte for dye-sensitized solar cells (DSSCs). Thus, di-tert-butylhydroquinone (DTHQ), thymohydroquinone (ThymHQ) and phenylhydroquinone (PhHQ), were combined with their oxidized counterparts to form the pairs DTHQ/DTBQ, ThymHQ/ThymBQ, and PhHQ/PhBQ. In general, the characteristic parameters of the DSSCs with the substituted derivatives surpassed those of the DSSC with the unsubstituted hydroquinone/benzoquinone electrolyte. The short-circuit current (J(sc)) of the devices using DTHQ/DTBQ and ThymHQ/ThymBQ (13.61 mA cm(-2) and 12.56 mA cm(-2), respectively) are comparable to the J(sc) obtained for cobalt(II/III) tris (bipyridine) as a reference electrolyte (14.54 mA cm(-2)). However, parameters such as open-circuit voltage (V-oc) and fill factor (FF) (547 mV and 0.48, respectively) are far from competitive. The best photovoltaic performance was obtained for the pair ThymHQ/ThymBQ using a triphenylamine (TPA)-based organic dye (LEG4) as sensitizer and a hybrid counter electrode with poly(3,4-ethylenedioxythiophene) (PEDOT) and graphene. These experimental conditions give under 1 sun (98%) the highest efficiency (eta = 3.19%); low-light intensities of 12.3% and 51.8% suns lead to efficiencies of 3.34% and 3.29%, respectively. Electrochemical impedance spectroscopy (EIS) revealed that the main cause for loss in photocurrent is the low recombination resistance compared to Co(II/III) as reference electrolyte. Based on the EIS analysis, a down-shift of the conduction band of TiO2 was found for all assembled devices containing the organic redox mediators, which explains the low V-oc values for these derivatives.

Producción Científica, Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)

The system KSCN-H2O2-CuSO4-NaOH, also known as the OrbA n-Epstein oscillatory reaction, is exposed to external perturbations by several phenolic compounds: catechol, resorcinol, hydroquinone, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, and ferulic acid. As a result of the performed perturbation in most examined cases, oscillations have been inhibited for some characteristic time, and resumed afterwards. The evaluated inhibition time is typical for each substance and strongly dependent on its concentration. The chemical mechanism of the interaction between the OrbA n-Epstein system and phenolic compounds is briefly discussed. Numerical simulations are performed using the original OrbA n-Epstein model with 30 reactions, extended by three reactions describing the interaction with inhibitory substances. The rate constants of three added reactions are adjusted to fit experimental inhibition times, and compared among used compounds. The observed effects are discussed further in relation with the bond dissociation enthalpy theory. Unlike other tested compounds, 2,5-dihydroxybenzoic acid remains off from predicted order of activity.

The system KSCN-H2O2-CuSO4-NaOH, also known as the OrbA n-Epstein oscillatory reaction, is exposed to external perturbations by several phenolic compounds: catechol, resorcinol, hydroquinone, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, and ferulic acid. As a result of the performed perturbation in most examined cases, oscillations have been inhibited for some characteristic time, and resumed afterwards. The evaluated inhibition time is typical for each substance and strongly dependent on its concentration. The chemical mechanism of the interaction between the OrbA n-Epstein system and phenolic compounds is briefly discussed. Numerical simulations are performed using the original OrbA n-Epstein model with 30 reactions, extended by three reactions describing the interaction with inhibitory substances. The rate constants of three added reactions are adjusted to fit experimental inhibition times, and compared among used compounds. The observed effects are discussed further in relation with the bond dissociation enthalpy theory. Unlike other tested compounds, 2,5-dihydroxybenzoic acid remains off from predicted order of activity.

Producción Científica, Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)

Producción Científica, Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R), Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)

The system KSCN-H2O2-CuSO4-NaOH, also known as the OrbA n-Epstein oscillatory reaction, is exposed to external perturbations by several phenolic compounds: catechol, resorcinol, hydroquinone, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, and ferulic acid. As a result of the performed perturbation in most examined cases, oscillations have been inhibited for some characteristic time, and resumed afterwards. The evaluated inhibition time is typical for each substance and strongly dependent on its concentration. The chemical mechanism of the interaction between the OrbA n-Epstein system and phenolic compounds is briefly discussed. Numerical simulations are performed using the original OrbA n-Epstein model with 30 reactions, extended by three reactions describing the interaction with inhibitory substances. The rate constants of three added reactions are adjusted to fit experimental inhibition times, and compared among used compounds. The observed effects are discussed further in relation with the bond dissociation enthalpy theory. Unlike other tested compounds, 2,5-dihydroxybenzoic acid remains off from predicted order of activity.

Висвітлено вплив різних концентрації гідрохінону (2 ГДК, 5 ГДК, 10 ГДК) на вміст молочної кислоти в органах мантійного комплексу Unio conus за різної тривалості перебування молюсків (1, 7, 14 діб) у токсичному середовищі., Освещенно влияние различных концентраций гидрохинона (2 ГДК, 5 ГДК, 10 ГДК) на содержание молочной кислоты в органах мантийного комплекса Unio conus при разной продолжительности пребывания моллюсков (1, 7, 14 сут) в токсической среде., The effect of the water environment hydroquinone (2 LPC, 5 LPC, 10 LPC concentration) on the lactic acid content in the organs of the mantle complex under the different duration period of molluska exposition in the toxic environment (1, 7, 14 days) has been investigated.

Висвітлено вплив гідрохінону у концентраціях 2 ГДК, 5 ГДК, 10 ГДК на вміст піровиноградної кислоти в мантії і зябрах U. conus за різної тривалості експозиції молюсків у токсичному середовищі (1, 7, 14 діб)., Освещено влияние гидрохинона в концентрациях 2 ГДК, 5 ГДК, 10 ГДК на содержание пировиноградной кислоты в мантии и жабрах U. conus при разной продолжительности экспозиции моллюсков в токсической среде (1, 7, 14 сут)., The paper deals with the influence of hydroquinone in the concentration of 2 LPC, 5 LPC and 10 LPC on the content of pyruvic acid in the U. conus mantle and gills under different duration of mollusks exposure in the toxic medium (1, 7, 14 cm).

Висвітлено вплив гідрохінону у концентраціях 2 ГДК, 5 ГДК, 10 ГДК на вміст піровиноградної кислоти в мантії і зябрах U. conus за різної тривалості експозиції молюсків у токсичному середовищі (1, 7, 14 діб)., Освещено влияние гидрохинона в концентрациях 2 ГДК, 5 ГДК, 10 ГДК на содержание пировиноградной кислоты в мантии и жабрах U. conus при разной продолжительности экспозиции моллюсков в токсической среде (1, 7, 14 сут)., The paper deals with the influence of hydroquinone in the concentration of 2 LPC, 5 LPC and 10 LPC on the content of pyruvic acid in the U. conus mantle and gills under different duration of mollusks exposure in the toxic medium (1, 7, 14 cm).

Висвітлено вплив різних концентрації гідрохінону (2 ГДК, 5 ГДК, 10 ГДК) на вміст молочної кислоти в органах мантійного комплексу Unio conus за різної тривалості перебування молюсків (1, 7, 14 діб) у токсичному середовищі., Освещенно влияние различных концентраций гидрохинона (2 ГДК, 5 ГДК, 10 ГДК) на содержание молочной кислоты в органах мантийного комплекса Unio conus при разной продолжительности пребывания моллюсков (1, 7, 14 сут) в токсической среде., The effect of the water environment hydroquinone (2 LPC, 5 LPC, 10 LPC concentration) on the lactic acid content in the organs of the mantle complex under the different duration period of molluska exposition in the toxic environment (1, 7, 14 days) has been investigated.

Висвітлено вплив гідрохінону у концентраціях 2 ГДК, 5 ГДК, 10 ГДК на вміст піровиноградної кислоти в мантії і зябрах U. conus за різної тривалості експозиції молюсків у токсичному середовищі (1, 7, 14 діб)., Освещено влияние гидрохинона в концентрациях 2 ГДК, 5 ГДК, 10 ГДК на содержание пировиноградной кислоты в мантии и жабрах U. conus при разной продолжительности экспозиции моллюсков в токсической среде (1, 7, 14 сут)., The paper deals with the influence of hydroquinone in the concentration of 2 LPC, 5 LPC and 10 LPC on the content of pyruvic acid in the U. conus mantle and gills under different duration of mollusks exposure in the toxic medium (1, 7, 14 cm).

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

A series of pyrroles functionalized in the 3-position with p-dimethoxybenzene via various linkers (CH2, CH2CH2, CH=CH, C≡C) has been synthesized. Their electronic properties have been deduced from 1H NMR, 13C NMR, and UV–vis spectra to detect possible interactions between the two aromatic subunits. The extent of conjugation between the subunits is largely controlled by the nature of the linker, with the largest conjugation found with the trans-ethene linker and the weakest with the aliphatic linkers. DFT calculations revealed substantial changes in the HOMO–LUMO gap that correlated with the extent of conjugation found experimentally. The results of this work are expected to open up for use of the investigated compounds as components of redox-active materials in sustainable, organic electrical energy storage devices.

A series of pyrroles functionalized in the 3-position with p-dimethoxybenzene via various linkers (CH2, CH2CH2, CH=CH, C≡C) has been synthesized. Their electronic properties have been deduced from 1H NMR, 13C NMR, and UV–vis spectra to detect possible interactions between the two aromatic subunits. The extent of conjugation between the subunits is largely controlled by the nature of the linker, with the largest conjugation found with the trans-ethene linker and the weakest with the aliphatic linkers. DFT calculations revealed substantial changes in the HOMO–LUMO gap that correlated with the extent of conjugation found experimentally. The results of this work are expected to open up for use of the investigated compounds as components of redox-active materials in sustainable, organic electrical energy storage devices.

A series of pyrroles functionalized in the 3-position with p-dimethoxybenzene via various linkers (CH2, CH2CH2, CH=CH, C≡C) has been synthesized. Their electronic properties have been deduced from 1H NMR, 13C NMR, and UV–vis spectra to detect possible interactions between the two aromatic subunits. The extent of conjugation between the subunits is largely controlled by the nature of the linker, with the largest conjugation found with the trans-ethene linker and the weakest with the aliphatic linkers. DFT calculations revealed substantial changes in the HOMO–LUMO gap that correlated with the extent of conjugation found experimentally. The results of this work are expected to open up for use of the investigated compounds as components of redox-active materials in sustainable, organic electrical energy storage devices.

INTRODUCTION: Nevoid hyperkeratosis of the nipple and/or areola (NHNA) is a benign lesion with a female predominance and an aesthetically disturbing appearance. Spontaneous remission is not reported and medical treatments proposed so far have shown variable results. PRESENTATION OF CASE: We describe a rare case of an extensive variant of NHNA covering almost the entire breasts' surface. At present, only three other reports are present in the literature. Medical treatment proved not completely effective and the patient was also affected by a significant breast asymmetry hypertrophy. Therefore, NHNA was managed surgically with excision of the areolar affected portions while performing breast reduction-lift. The result was satisfactory and without recurrence of lesions at 5-year follow-up. DISCUSSION: This case reported favorable outcomes of surgery for NHNA. Reports of success with these procedures are still limited, but the promising results in terms of radicality and aesthetic outcome suggest it should be offered to patients as a viable therapeutic option. CONCLUSION: Indications for surgical treatment of NHNA can be: unsatisfying response to topical agents; young patients who want to restore the aesthetic appearance of the breast; and patients with concomitant indication for corrective surgery of the breast. Advantages are: predictable time of healing; predictable final result; radical excision of the affected tissue; and possibility of histologic analysis of the whole areola. In rare cases of lesions extending to the breast, preliminary treatment with topical agents can limit the extent of excision. Management and treatment should always be tailor-made for each individual case.

INTRODUCTION: Nevoid hyperkeratosis of the nipple and/or areola (NHNA) is a benign lesion with a female predominance and an aesthetically disturbing appearance. Spontaneous remission is not reported and medical treatments proposed so far have shown variable results. PRESENTATION OF CASE: We describe a rare case of an extensive variant of NHNA covering almost the entire breasts' surface. At present, only three other reports are present in the literature. Medical treatment proved not completely effective and the patient was also affected by a significant breast asymmetry hypertrophy. Therefore, NHNA was managed surgically with excision of the areolar affected portions while performing breast reduction-lift. The result was satisfactory and without recurrence of lesions at 5-year follow-up. DISCUSSION: This case reported favorable outcomes of surgery for NHNA. Reports of success with these procedures are still limited, but the promising results in terms of radicality and aesthetic outcome suggest it should be offered to patients as a viable therapeutic option. CONCLUSION: Indications for surgical treatment of NHNA can be: unsatisfying response to topical agents; young patients who want to restore the aesthetic appearance of the breast; and patients with concomitant indication for corrective surgery of the breast. Advantages are: predictable time of healing; predictable final result; radical excision of the affected tissue; and possibility of histologic analysis of the whole areola. In rare cases of lesions extending to the breast, preliminary treatment with topical agents can limit the extent of excision. Management and treatment should always be tailor-made for each individual case.

INTRODUCTION: Nevoid hyperkeratosis of the nipple and/or areola (NHNA) is a benign lesion with a female predominance and an aesthetically disturbing appearance. Spontaneous remission is not reported and medical treatments proposed so far have shown variable results. PRESENTATION OF CASE: We describe a rare case of an extensive variant of NHNA covering almost the entire breasts' surface. At present, only three other reports are present in the literature. Medical treatment proved not completely effective and the patient was also affected by a significant breast asymmetry hypertrophy. Therefore, NHNA was managed surgically with excision of the areolar affected portions while performing breast reduction-lift. The result was satisfactory and without recurrence of lesions at 5-year follow-up. DISCUSSION: This case reported favorable outcomes of surgery for NHNA. Reports of success with these procedures are still limited, but the promising results in terms of radicality and aesthetic outcome suggest it should be offered to patients as a viable therapeutic option. CONCLUSION: Indications for surgical treatment of NHNA can be: unsatisfying response to topical agents; young patients who want to restore the aesthetic appearance of the breast; and patients with concomitant indication for corrective surgery of the breast. Advantages are: predictable time of healing; predictable final result; radical excision of the affected tissue; and possibility of histologic analysis of the whole areola. In rare cases of lesions extending to the breast, preliminary treatment with topical agents can limit the extent of excision. Management and treatment should always be tailor-made for each individual case.