Unidentified Products Research Articles

LC–MS/MS and in silico analysis of pharmaceutical impurities in a combination drug for hypertension

AbstractThis study intends to develop an essential simultaneous analysis method for the stability study of the combination drugs hydrochlorothiazide, (S)‐amlodipine besylate, and olmesartan medoxomil and identify degradation products. A stress test of the combination drug was performed under thermal/humidity conditions to identify decomposition products expected to be generated under long‐term storage conditions. Six unidentified degradation products were generated from (S)‐amlodipine besylate and olmesartan medoxomil, except for those identified. Unspecified degradation products were identified by degradation prediction software with LC–MS/MS, and genotoxicity was predicted by toxicity prediction software. In silico toxicity, six degradation products were expected to be nonmutagenic. This study describes the development of an analytical method to predict degradation products and determine whether the degradation products are genotoxic. This process will be helpful in further forced degradation studies to predict the toxicity of potential impurities.

Calculation of the relative basicity of three α,ω‐diphenylpolyenes with trifluoroacetic acid

AbstractLinear polyenes are an important class of compounds containing two or more alternating carbon‐carbon double and single bonds that are soluble primarily in organic non‐polar solvents. However, determining the relative basicity of unsubstituted polyenes experimentally has proven to be challenging in practice because such studies require mixing non‐polar polyene‐organic solvent mixtures with high concentrations of moderately polar organic acids. In this study, we used both computational and experimental approaches to calculate potential sites of protonation of trans‐1,4‐diphenyl‐1,3‐butadiene (DPB), all trans‐1,6‐diphenyl‐1,3,5‐hexatriene (DPH), and all trans‐1,8‐diphenyl‐1,3,5,7‐octatetraene (DPO) with trifluoroacetic acid (TFAH) in both n‐hexane or benzene solvents. Density functional theory (DFT) calculations with a 6‐311 + G (d,p) basis set and the B3LYP exchange correlation functional predict that the carbon atoms α to either phenyl ring are the most likely sites of protonation. Our calculations indicate that the basicities of the DPPs increase with increasing length of the polyene moiety (DPO > DPH >> DPB) in the gas phase and in both benzene and n‐heptane solvents. Consistent with these computational predictions, the experimental rates of protonation of DPB, DPH, and DPO in benzene and hexane were consistent with the calculated basicity trends. Dynamic light scattering data confirmed that these reactions were phase separated resulting in emulsions between TFAH and both solvents; these phase separations complicated specification of the actual reaction rates. Finally, GC‐MS and NMR data confirm that the crude products from the protonation of DPB and DPH were mixtures of DPB and DPH dimers. In significant contrast, DPO did not form dimers but rather an unidentified monomeric trifluoroacetate addition product.

Biochemistry of the Endocrine Heart.

Simple SummaryBesides being a muscle and an electrochemically active organ, the heart is a true endocrine organ. As endocrine cells, cardiac myocytes possess all the needed chemical necessities for translation, post-translational modifications, and complex peptide proteolysis. In addition, intracellular granules in the cells contain not only peptides destined for secretion but also important granin molecules involved in maintaining a regulated secretory pathway. In this review, we highlight the biochemical phenotype of the endocrine heart, recapitulating that the cardiac myocytes are truly and fully capable endocrine cells.Production and release of natriuretic peptides and other vasoactive peptides are tightly regulated in mammalian physiology and involved in cardiovascular homeostasis. As endocrine cells, the cardiac myocytes seem to possess almost all known chemical necessities for translation, post-translational modifications, and complex peptide proteolysis. In several ways, intracellular granules in the cells contain not only peptides destined for secretion but also important granin molecules involved in maintaining a regulated secretory pathway. In this review, we will highlight the biochemical phenotype of the endocrine heart recapitulating that the cardiac myocytes are capable endocrine cells. Understanding the basal biochemistry of the endocrine heart in producing and secreting peptides to circulation could lead to new discoveries concerning known peptide products as well as hitherto unidentified cardiac peptide products. In perspective, studies on natriuretic peptides in the heart have shown that the post-translational phase of gene expression is not only relevant for human physiology but may prove implicated also in the development and, perhaps one day, cure of human cardiovascular disease.

An ambiguity of laser‐induced degradation in LiFePO4 and advantages of single‐particle approach to Raman spectroscopy

AbstractLaser‐induced degradation is a common issue for the Raman spectroscopy study of lithium battery materials. In this work, the combination of single‐particle Raman measurements with scanning electron microscope imaging helped us reveal the variation of the decomposition pathways and products. For the first time, we observed possible laser‐induced melting of the LiFePO4 particles and an unidentified decomposition product, an alternative to previously reported α‐Fe2O3 and γ‐Li3Fe2(PO4)3. These results and analysis of the time series of Raman measurements raise doubts about laser‐induced heating. We suppose non‐thermal amorphization and melting processes due to electronic system excitation by intraband transitions with the following covalent bond destabilization. The role of defects in laser‐induced decomposition is discussed. We hope that this article could help develop a non‐destructive tool for quality control and the study of the electrochemical or thermal degradation of LiFePO4.

The Synthesis of (2R)-Aziridine-2-carboxylic Acid Containing Dipeptides.

Optimized conditions for the synthesis of fully deprotected (2R)-aziridine containing dipeptides are described. Preparation of fully protected N- and C- terminal aziridine containing dipeptides was found to be straightforward and high yielding for the majority of compounds, whereas their full deprotection was possible only for C-terminal analogs. Deprotection of N-terminal derivatives using standard procedures of peptide chemistry was found difficult providing only mixtures of unidentifiable products. The described molecules have potential as building blocks in synthetic chemistry, in the chemical biology arena, as covalent modifiers, and as biomarkers.

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Access to a Labile Monomeric Magnesium Radical by Ball‐Milling

AbstractIn order to isolate a monometallic Mg radical, the precursor (Am)MgI⋅(CAAC) (1) was prepared (Am=tBuC(N‐DIPP)2, DIPP=2,6‐diisopropylphenyl, CAAC=cyclic (alkyl)(amino)carbene). Reduction of a solution of 1 in toluene with the reducing agent K/KI led to formation of a deep purple complex that rapidly decomposed. Ball‐milling of 1 with K/KI gave the low‐valent MgI complex (Am)Mg⋅(CAAC) (2) which after rapid extraction with pentane and crystallization was isolated in 15 % yield. Although a benzene solution of 2 decomposes rapidly to give Mg(Am)2 (3) and unidentified products, the radical is stable in the solid state. Its crystal structure shows planar trigonal coordination at Mg. The extremely short Mg−C distance of 2.056(2) Å indicates strong Mg−CAAC bonding. Calculations and EPR measurements show that most of the spin density is in a π* orbital located at the C−N bond in CAAC, leading to significant C−N bond elongation. This is supported by calculated NPA charges in 2: Mg +1.73, CAAC −0.82. Similar metal‐to‐CAAC charge transfer was calculated for M0(CAAC)2 and [MI(CAAC)2+] (M=Be, Mg, Ca) complexes in which the metal charges range from +1.50 to +1.70. Although the spin density of the radical is mainly located at the CAAC ligand, complex 2 reacts as a low‐valent MgI complex: reaction with a I2 solution in toluene gave (Am)MgI⋅(CAAC) (1) as the major product.

Access to a Labile Monomeric Magnesium Radical by Ball-Milling.

In order to isolate a monometallic Mg radical, the precursor (Am)MgI⋅(CAAC) (1) was prepared (Am=tBuC(N‐DIPP)2, DIPP=2,6‐diisopropylphenyl, CAAC=cyclic (alkyl)(amino)carbene). Reduction of a solution of 1 in toluene with the reducing agent K/KI led to formation of a deep purple complex that rapidly decomposed. Ball‐milling of 1 with K/KI gave the low‐valent MgI complex (Am)Mg⋅(CAAC) (2) which after rapid extraction with pentane and crystallization was isolated in 15 % yield. Although a benzene solution of 2 decomposes rapidly to give Mg(Am)2 (3) and unidentified products, the radical is stable in the solid state. Its crystal structure shows planar trigonal coordination at Mg. The extremely short Mg−C distance of 2.056(2) Å indicates strong Mg−CAAC bonding. Calculations and EPR measurements show that most of the spin density is in a π* orbital located at the C−N bond in CAAC, leading to significant C−N bond elongation. This is supported by calculated NPA charges in 2: Mg +1.73, CAAC −0.82. Similar metal‐to‐CAAC charge transfer was calculated for M0(CAAC)2 and [MI(CAAC)2 +] (M=Be, Mg, Ca) complexes in which the metal charges range from +1.50 to +1.70. Although the spin density of the radical is mainly located at the CAAC ligand, complex 2 reacts as a low‐valent MgI complex: reaction with a I2 solution in toluene gave (Am)MgI⋅(CAAC) (1) as the major product.

Laccase-mediated modification of isorhamnetin improves antioxidant and antibacterial activities

The enzymatic modification of phenolic molecules to higher molecular weight compounds is a promising approach for improving biological activity. In the current study, the Trametes pubescens laccase was used to modify isorhamnetin (m/z 315) as a way of improving its antioxidant and antibacterial activities. Using a monophasic system with ethanol as co-solvent, laccase-catalysed oxidation of isorhamnetin produced a dimer, IP1 (m/z 629, yield 28.8 %) and an unidentified product, IP2 (m/z 457, yield 21.8 %). The dimer showed twice the antioxidant capacity of isorhamnetin, while the unidentified product IP2 was less active than isorhamnetin. Listeria monocytogenes and methicillin-resistant Staphylococcus aureus showed susceptibility to IP1 (minimum inhibitory concentration two times lower compared to isorhamnetin), while Pseudomonas aeruginosa was susceptible to IP2 (minimum inhibitory concentration two times lower compared to isorhamnetin). Both oxidation products showed a bactericidal mode of action; membrane destruction was evidenced by loss of cell constituents in cell integrity assays, and by cell pores and fragmentations observed in scanning electron microscopy images. The dimer had improved antioxidant and antibacterial activities and may be exploited for nutraceutical purposes and in other relevant industries. The product IP2 may also be useful in the treatment of Gram-negative infections associated with P. aeruginosa.

Development and Validation of a Stability-Indicating HPLC Method for the Simultaneous Determination of trans-Resveratrol and cis-Resveratrol in an Injectable Solution.

trans-Resveratrol, a phytochemical compound with antioxidant power and various therapeutic effects, such as cardioprotective, chemopreventive, and neuroprotective, among others, has disadvantages of poor solubility and limited stability, creating difficulties for the development of new strategies for its quantification. This study developed and validated an analytical stability method for trans-resveratrol by high-pressure liquid chromatography with photodiode-array detection (HPLC-PDA), which allowed its quantification in the presence of its degradation products. The quantification of trans-resveratrol occurred at a retention time of 2.6 min, with ammonium formate (10 mM, pH = 4)/acetonitrile, 70/30 v/v, as mobile phase. The validation met the ICH Q2 criteria of specificity, method linearity (2.8–4.2 μg/ml), precision and accuracy, robustness, quantification limit (0.176 μg/ml), and detection (0.058 μg/ml). As degradation products, cis-resveratrol was observed at 3.9 min, which could be resveratrone in 3.2 min and five unidentified products in 0.7, 1.0, 1.4, 1.8, and 5 min. Some solutions subjected to temperature stress of 40 and 60°C, UV light, and acidic and basic hydrolysis exhibited colour changes. An analytical method was obtained by HPLC-PDA, which allowed quantifying the stability of trans-resveratrol in a fast and specific manner in the presence of its degradation products.

Amphorae of Roman Time from Excavations at Settlement on Berezan Island (in Collection of Odesa Archaeological Museum of NAS of Ukraine)

The author presents the finds of amphorae of the Roman time, which were found on the island of Berezan. Materials that are introduced into scientific circulation are stored in the depositaries of the Odesa Archaeological Museum of the National Academy of Sciences of Ukraine. They are mainly represented by fragments of amphorae, which were found as a result of the work of archaeological expeditions headed by M.F. Boltenko (1927, 1928, 1930, 1931, 1946) and V.V. Lapin (1960, 1961) at Berezan settlement. Some of the finds also came from the island of Berezan, but the year and place of their finding are unknown.
 A comprehensive study of amphorae fragments gives the opportunity to reconstruct the trade relations of the settlement, which was located on the island of Berezan in the first centuries AD. Products in transport amphorae appeared on the island in the early Roman time. Thus, in amphorae of type Vnukov S І, dating no later than the first third of the 2nd century AD, Heraclean wine, made according to Coan recipe, was imported. Subsequently, the products of Heraclea Pontica sporadically came in amphorae of variant Vnukov S IVC.
 The peak of trade activity of the settlement was attained in the end of the 2nd – the middle of the 3rd century AD. The range of products imported in transport wares during that period was rather wide. Heraclean wine was imported in large quantities (in amphorae of variant Vnukov S IVD) as opposed to much lesser quantities of the Aegean wine (in vessels of type Kapitän II) and Cilicia wine (in amphora of type Agora G 199). Probably, there was wine in amphora of type Zeest 72 or Zeest 73, which came to the island from an unidentified production site.
 Bosporus ‘salsamentum’, which had been very popular among the inhabitants of Berezan settlement since the end of the 2nd century AD was transported in amphorae of type Zeest 75 (variants A, C, D), and from the beginning of the 3rd century AD, also in a rather rare container of type Krapivina 27 (variants ‘a’ and ‘b’). Salted fish was also imported from the non-localized center in vessels of variant Zeest 75B. In addition, a small amount of purchased olive oil was imported in amphorae of type Zeest 80 from several production sites located in the Aegean and the Black Sea regions. Single items represent variants of amphorae that cannot be correlated with already known types.
 In Berezan collection of the Odesa Archaeological Museum of the National Academy of Sciences of Ukraine, no ceramic containers were found, which could be dated only later than 264. However, vessels of types Zeest 72 and Kapitän II could come to Berezan in the 4th century AD.

Clostridium chrysemydis sp. nov., isolated from the faecal material of a painted turtle.

A strict anaerobic, Gram-stain-positive rod-shaped bacterium, designated PTT, was isolated from the faecal material of a painted turtle (Chrysemys picta). Based on a comparative 16S rRNA gene sequence analysis, the isolate was assigned to Clostridium sensu stricto with the highest sequence similarities to Clostridium moniliforme (97.4 %), Clostridium sardiniense (97.2 %) and the misclassified organism Eubacterium multiforme (97.1 %). The predominant cellular fatty acids of strain PTT were C14 : 0, C16 : 0 and an unidentified product with an equivalent chain length of 14.969. The G+C content determined from the genome was 28.8 mol%. The fermentation end products from glucose were acetate and butyrate with no alcohols detected and trace amounts of CO2 and H2 also detected; no respiratory quinones were detected. Based on biochemical, phylogenetic, genotypic and chemotaxonomic criteria, the isolate represents a novel species of the genus Clostridium for which the name Clostridium chrysemydis sp. nov. is proposed. The type strain is strain PTT (=CCUG 74180T=ATCC TSD-219T).

THE VALUE OF THE NON-USER: DEVELOPING (NON-)USER PROFILES FOR THE DEVELOPMENT OF A ROBOT VACUUM WITH THE USE OF THE (NON-)PERSONA

AbstractThis contribution explores non-user integration in a product development context of the development of a vacuum robot in order to analyse users as well as non-users of a product. While user profiles like the persona have been part of product development and product design for years, the non-user has not been widely explored.Within this contribution the known concept of the persona is extended and further developed to the non-persona, a profile that describes non-users and why they do not use a certain product, in this case the vacuum robot. Including the non-user in product development offers the chance of addressing yet unidentified product requirements and therefore opening the product up to a bigger audience. This template works for both users and non-users and can be used to include both sides in a development project.

Nitrogen and oxygen isotopomeric constraints on the sources of nitrous oxide and the role of submarine groundwater discharge in a temperate eutrophic salt‐wedge estuary

AbstractEstuaries have been identified as sources of nitrous oxide (N2O) emissions to the atmosphere but questions remain as to which production pathway(s) govern the oversaturation of N2O observed in most estuaries worldwide. Here, we use a suite of nitrate and N2O isotopes, as well as the 15N site preference signatures of N2O to assess (1) the relative importance of different N2O production pathways in a eutrophic groundwater‐impacted salt‐wedge estuary and the aquifers underlying the estuary and (2) the influence of groundwater input on the overall N2O saturation in the estuary. This is one of the few studies to examine the effect of groundwater–surface water interaction on N2O cycling using N2O isotopes. The site preference values of N2O in the deep aquifer below the estuary were distinctive (83‰ ± 25‰) and were much higher than in either surface water (21‰ ± 6‰) or shallow groundwater (44‰ ± 8‰), suggesting the influence of multiple biotic and/or abiotic processes which proceed through multiple cycles, and/or the occurrence of a yet unidentified N2O production pathway. Isotope endmember considerations revealed that nitrifier‐denitrification was the major N2O production pathway within the shallow aquifer whereas within the estuarine water column, N2O saturation was governed by chemodenitrification and discharge of N2O‐laden submarine groundwater. Our study not only emphasizes the substantial, yet often underappreciated role of submarine groundwater discharge in estuarine N2O budgets, but also highlights the need to reevaluate the importance of the noncanonical denitrification pathways (i.e., chemodenitrification and nitrifier‐denitrification) in controlling the overall N2O production from estuarine and groundwater environments.

Utilization of mango wastes as a potential feedstock for the production of HMF

Agro-industrial wastes could become a source of revenue through their valorization while reducing their management and disposal issues. In this work, residues from the mango industry have been investigated as a source of sugars for the synthesis of 5-hydroxymethylfurfural (HMF), a high value platform chemical. Mangoes, which were past the last stage of ripening, were used as feedstock for microwave-assisted synthesis of HMF under hydrothermal conditions. The product was quantified through HPLC-DAD. The experimental conditions permitted a maximal HMF yield of 21.2 mol% in a 20-min reaction time at 150 °C with a 1:19 dilution ratio. The advantages of the synthesis pathway include the use of microwave heating and water as solvent media, which renders the reaction pathway eco-friendly. High temperatures and prolonged reaction times seem to lead to unidentified side products which lead to a reduction in HMF yield. The results presented in this work highlight mango fruit waste as a potential biomass for HMF production. This would give value to a current agro-industrial waste while attending to current problems linked to its disposal.

Gas-Phase Optical Detection of 3-Ethynylcyclopentenyl: A Resonance-Stabilized C7H7 Radical with an Embedded 1-Vinylpropargyl Chromophore.

The 3-ethynylcyclopentenyl radical (3ecpr) has been identified as the carrier of an electronic spectrum with origin at 21792 cm-1 using resonant ionization and laser-induced fluorescence spectroscopies. The radical was first detected in a toluene discharge and is most efficiently produced from 1,6-heptadiyne. Overwhelming spectroscopic and chemical evidence support our diagnosis: (1) the observed (6.93 eV) and calculated (CCSD(T)/pVQZ) adiabatic ionization energies are the same; (2) the origin band rotational contour can be well simulated with calculated rotational constants; (3) convincing vibrational assignments can be made using computed frequencies; and (4) the same spectrum was observed in a discharge of 1-ethynylcyclopentanol, which contains the 3ecpr carbon framework. The π-chromophore is essentially that of trans-1-vinylpropargyl, a highly resonance-stabilized C5H5 radical that persists in conditions relevant to both combustion and circumstellar atmospheres. We suggest that 3ecpr may be a similarly important radical warranting inclusion in models of C7H7 chemistry. It is the second C7H7 isomer with a five-membered ring yet to be detected, the other being vinylcyclopentadienyl, a species crucially involved in a recently proposed mechanism of soot formation (Science, 2018, 361, 6406, 997-1000). We argue that 3ecpr should be a significant product of H addition to ethynylcyclopentadiene (C7H6), a known product of benzyl decomposition. Further, it is plausible that 3ecpr is the unidentified C7H7 product of sequential addition of acetylene to propargyl (J. Phys. Chem. Lett., 2015, 6, 20, 4153-4158) in which 1-vinylpropargyl is an intermediate. As such, the nC2H2 + C3H3 cascade could represent a facile synthesis of a substituted five-membered ring in flames and stellar outflows.

Genus specific PCR-RFLP and multiplex PCR for diagnosis of avian mycoplasmosis

Diagnosis of avian mycoplasmosis remains a serious problem, due to unusual nature of etiological agent. Although, many protocols for PCR are set with the published primers; they do not always yield vis-à-vis results under different existing conditions of laboratories. Therefore, the present research was aimed towards the optimization and evaluation of genus specific and multiplex PCR for molecular diagnosis of avian mycoplasmosis. The research was carried out systematically where in first DNA extraction protocol was standardized followed by optimization of PCR. Using optimized protocols, screening of 165 clinical specimens from mycoplasmosis suspected birds was carried out employing genus specific PCR-RFLP, followed by the confirmation of positive samples by multiplex PCR assay and sequencing of unidentified PCR products. Phenol chloroform isoamyl method was found superior to rapid heat freeze method for extraction of better quality and quantity of DNA. Genus specific 16S rRNA based PCR-RFLP was found sensitive and convenient method for screening large number of clinical specimens for detection of mycoplasma infection.

Conversion of Glucose to 5-Hydroxymethylfurfural (5-HMF) Over Sulfated Zinc Oxide Catalyst

Zinc oxide and sulfated zinc oxide catalysts prepared by precipitation and wetness impregnation methods, respectively, and characterized by various sophisticated techniques like XRD, FE-SEM, EDX, TGA, NH3-TPD and N2 adsorption-desorption. These catalysts tested for glucose dehydration to 5-hydroxymethylfurfural (5-HMF) formation and the influence of several reaction constraints as reaction temperature, reaction time, catalyst amount, and sulfation loading on ZnO were evaluated in terms of glucose conversion and 5-HMF Yield. Catalytic activity results demonstrated a maximum of 15.8 % 5-HMF yield with complete conversion of glucose over 2.5M SO42-/ZnO catalyst at 220°C after a reaction time of 6 h in the presence of dimethyl sulfoxide (DMSO) reaction solvent. The formation of other unidentified side reaction products restricted the higher yield of HMF. Reaction parameter study suggested that higher reaction temperature (> 220oC), higher substrate to catalyst ratio (> 0.5) was not beneficial for higher yield of HMF. Longer reaction time has not affected the yield of HMF. The results obtained also suggested that the acidic nature of catalyst was responsible for the high conversion of glucose.

Cycloaddition of Alkenes and Alkynes to the P‐centered Singlet Biradical [P(μ‐NTer)]2

The reaction of biradical [P(μ‐NTer)]2 (1, Ter = 2,6‐bis(2,4,6‐trimethylphenyl)phenyl) towards different alkenes (R = 2,3‐dimethyl–butadiene, 2,5‐dimethyl‐2,4‐hexadiene, 1,7‐octadiene, 1,4‐cyclohexadiene) and alkynes (R = 1,4‐diphenyl‐1,3‐butadiyne) was studied experimentally. Although these olefins can react in different ways, only [2+2] cycloaddition products (1R) were observed. The reaction with 2,3‐dimethylbutadiene also led to the [2+2] product (1dmb). Thermal treatment of 1dmb above 140 °C resulted in the recovery of biradical 1 upon homolytic bond cleavage of the two P–C bonds and the release of 2,3‐dimethylbutadiene. In contrast to this reaction, all other [2+2] additions products (1R, R = 1,7‐octadiene, 1,4‐cyclohexadiene, 1,4‐diphenyl‐1,3‐butadiyne) began to decompose at temperatures between 200 °C and 300 °C. Only unidentified products were obtained but no temperature‐controlled equilibrium reactions were observed. Computations were carried out to shed light into the formal [2+2] as well as the possible [4+2] addition reaction.

Nitric oxide (NO) in the Bohai Sea and the Yellow Sea

Abstract. Nitric oxide (NO) is a short-lived compound of the marine nitrogen cycle; however, our knowledge about its oceanic distribution and turnover is rudimentary. Here we present the measurements of dissolved NO in the surface and bottom layers at 75 stations in the Bohai Sea (BS) and the Yellow Sea (YS) in June 2011. Moreover, NO photoproduction rates were determined at 27 stations in both seas. The NO concentrations in the surface and bottom layers were highly variable and ranged from below the limit of detection (i.e., 32 pmol L−1) to 616 pmol L−1 in the surface layer and 482 pmol L−1 in the bottom layer. There was no significant difference (p>0.05) between the mean NO concentrations in the surface (186±108 pmol L−1) and bottom (174±123 pmol L−1) layers. A decreasing trend of NO in bottom-layer concentrations with salinity indicates a NO input by submarine groundwater discharge. NO in the surface layer was supersaturated at all stations during both day and night and therefore the BS and YS were a persistent source of NO to the atmosphere at the time of our measurements. The average flux was about 4.5×10-16 mol cm−2 s−1 and the flux showed significant positive relationship with the wind speed. The accumulation of NO during daytime was a result of photochemical production, and photoproduction rates were correlated to illuminance. The persistent nighttime NO supersaturation pointed to an unidentified NO dark production. NO sea-to-air flux densities were much lower than the NO photoproduction rates. Therefore, we conclude that the bulk of the NO produced in the mixed layer was rapidly consumed before its release to the atmosphere.