ライフサイエンスコーパス: humic

1 DOM (more humic) to a low-colored DOM (less humic).

2 and electron shuttling reactions mediated by humics.

3 The experimental chamber contained water, humic acid (1-10 mg L(-1)) as a proxy for dissolved orga

4 udies and differing from sorption to Aldrich-humic acid (AHA) utilized as reference sorbent.

5 r natural organic matter (SRNOM) and Aldrich humic acid (ALHA), in the dark ambient condition, while

6 eonardite humic acid (LAHA) and Florida peat humic acid (FPHA), at concentrations above 5 mg C/L, sho

7 Insight in the molecular structure of humic acid (HA) and fulvic acid (FA) can contribute to i

8 ar level of understanding on the dynamics of humic acid (HA) and its interaction with uranyl in the p

9 mpure samples using the common PCR inhibitor humic acid (HA) as a model.

10 tions of variable NaNO(3), Ca(NO(3))(2), and humic acid (HA) concentrations were used to differentiat

11 The presence of humic acid (HA) did not hinder DCF removal by the compos

12 Humic acid (HA) is thought to promote NO2 conversion to

13 ferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite w

14 We examined the impact of Suwannee River humic acid (HA) on the toxicity of TiO2NPs to developing

15 cies (ROS) by C60 under UV irradiation, when humic acid (HA) or fulvic acid (FA) is present.

16 liott soil, Pahokee peat, and Suwannee river humic acid (HA) samples before and after sorption to pol

17 uspensions and Ag(+) in solution when adding humic acid (HA) to bacterial suspensions.

18 The addition of humic acid (HA) to the exposure media significantly decr

19 untreated and electrochemically reduced soil humic acid (HA) under oxic and anoxic conditions.

20 A lignite humic acid (HA) was separated from inorganic and non-HA

21 bsorbing brown carbon surrogate derived from humic acid (HA) were measured across the visible to near

22 The presence of humic acid (HA), as an analog of soil organic matter, do

23 on with reduced and nonreduced Sigma-Aldrich humic acid (HA), at pH 6 under anoxic conditions.

24 Humic acid (HA), further increased their size and polydi

25 45 mV) increased the adsorption of EfOM and humic acid (HA), moderately and sharply, respectively, s

26 igated iodine and carbon speciation in three humic acid (HA)-I systems using I K-edge XANES and EXAFS

27 erface, association of fullerene to pure and humic acid (HA7) coated gammaFe2O3 NPs led to the format

28 A de-ashed humic acid (i.e., metals being removed) scavenged more P

29 The two terrestrial HAs, namely Leonardite humic acid (LAHA) and Florida peat humic acid (FPHA), at

30 s at mineral surfaces coated with Leonardite humic acid (LHA).

31 tained by photosensitization by Pahokee Peat Humic Acid (PPHA) and Suwannee River Fulvic Acid (SRFA),

32 investigated as a function of Suwannee River Humic Acid (SRHA) and background electrolyte concentrati

33 ) water at pH 5.6 +/- 0.2 and Suwannee River humic acid (SRHA) at pH 5.1 +/- 0.2 using low doses of c

34 c lake fulvic acid, NLFA) and Suwannee River humic acid (SRHA) followed the order NLFA > SRHA > PPFA

35 Suwanee River Humic Acid (SRHA) was also used to determine the effect

36 Suwannee River humic acid (SRHA) was used to study the effects of natur

37 n the presence and absence of Suwannee River humic acid (SRHA).

38 We developed a new humic acid adsorption method for determining the relativ

39 For humic acid aerosols, uptake coefficients in the range of

40 ring the initial stage of Hg(0) oxidation by humic acid and attributed to the kinetic isotope effect

41 tion, suggesting a "blocking effect" between humic acid and bacterial cells.

42 In addition, both humic acid and FBS protein effectively lowered the amoun

43 Humic acid and FBS significantly changed the characteris

44 This research examined the effects of humic acid and fetal bovine serum (FBS), which are ubiqu

45 esence of the two model NOMs (Suwannee river humic acid and fulvic acid).

46 A water soluble humic acid and melanin-like polymer complex (OMWW-ASP) w

47 Humic acid and tryptophan featured larger increases in t

48 h both low and high proton-affinity sites of humic acid and zwitterion interaction with high proton-a

49 Elevated lead in the presence of humic acid appeared to be driven by complexation, with (

50 a photochemical chamber, with aerosol-phase humic acid as the photosensitizer and limonene as the VO

51 1000 +/- 3000 ppb) ions were measured in the humic acid atomizer solutions compared to the other orga

52 We observed that humic acid caused a similar level of inhibition in both

53 Easily separable humic acid coated magnetite (HA-Fe3O4) nanoparticles are

54 c carbon and water (KOC) and between Aldrich humic acid dissolved organic carbon and water (KDOC) for

55 Sulfide and humic acid each individually caused immediate increases

56 lead as insoluble hydroxypyromorphite, while humic acid enhanced lead mobility.

57 through the reduction of Ag(+) by fulvic and humic acid fractions of natural organic matter in the en

58 y related to the conformational structure of humic acid in solution and its interaction with the cell

59 larithromycin and tetracycline) to dissolved humic acid in the absence and presence of Ca(2+) and eva

60 t to clarithromycin, tetracycline binding to humic acid increased in the presence of Ca(2+), especial

61 In the presence of 20 ppm of humic acid of an organic-rich soil, plutonium diffusion

62 The effects of humic acid on lipid accumulation of fullerene depended o

63 a suggest that all of these actions of model humic acid on root functionality, which are linked to it

64 ively charged tetracycline-Ca complexes with humic acid rather than due to the formation of ternary c

65 an OM-poor clay soil, a hydrophilic Aldrich humic acid salt, and water-insoluble leonardite.

66 various concentrations (1, 2, and 5 mM) from humic acid samples (1 g HA/L) of different redox states.

67 ate and reliable determination of the EAC of humic acid samples.

68 r nanoparticles and nanoparticle spiked into humic acid solution (50 mg/L) at an environmentally rele

69 The presence of humic acid stabilized the system against heteroaggregati

70 background electrolyte) in Milli-Q water and humic acid suspensions.

71 in competition, it was the influence of the humic acid that dominated that of the sulfide.

72 The mechanism requires particle-phase humic acid to absorb solar radiation and become photoexc

73 t HULIS is equally or less reactive than the humic acid used in these experiments, the results sugges

74 polyacrylamide (PAM) gel in the presence of humic acid using a diffusion cell (D = 1.70 +/- 0.25 x 1

75 Clarithromycin interaction with dissolved humic acid was well described by the model including the

76 Two aquatic fulvic acids and one soil humic acid were irradiated to examine the resulting chan

77 caused by a structurally well-characterized humic acid with sedimentary origin is functionally assoc

78 aracteristics of Cd on montmorillonite(Mont)-humic acid(HA)-bacteria composites.

79 The addition of electron acceptors (e.g., humic acid) also led to substantially increased Hg(0)aq

80 n model dissolved organic matter (DOM; Fluka humic acid) can react via thermal substitution with TBA

81 temperature, alkalinity, ionic strength, and humic acid) inhibited overall neonicotinoid sorption, su

82 particle surface chemistry (PVP, citrate, or humic acid) on alpha, and found a strong dependence on b

83 sulfide and natural organic matter (NOM, as humic acid), while under suboxic conditions.

84 performance of the polymer is unaffected by humic acid, a component of natural organic matter that f

85 ce of Suwannee River natural organic matter, humic acid, and fulvic acid (SRNOM, SRHA, and SRFA), alg

86 otential of the photosensitizer chemistry of humic acid, as a proxy for humic-like substances in atmo

87 bited in the presence of radical scavengers (humic acid, carbonate), in complex aquatic matrices (Iow

88 he least to most inhibitive was Pahokee Peat humic acid, Elliot Soil humic acid, Suwannee River humic

89 monomethyl amine sulfate, and two sources of humic acid, for an initial HO2 concentration of 1 x 10(9

90 salicylic acid (SA), natural organic matter (humic acid, HA), and dissolved silicates.

91 ternary complex formation or, in the case of humic acid, incorporation into HA aggregates.

92 contaminated water sources such as chloride, humic acid, perfluorooctanoic acid (PFOA), and perfluoro

93 ive was Pahokee Peat humic acid, Elliot Soil humic acid, Suwannee River humic acid, Suwannee River NO

94 acid, Elliot Soil humic acid, Suwannee River humic acid, Suwannee River NOM, Suwannee River fulvic ac

95 In the case of chloride and humic acid, the calculated K(A) values of 9.05 x 10(7) a

96 uilibrated models of the standard Leonardite humic acid, together with corresponding force-field para

97 was also observed for four model precursors (humic acid, tryptophan, tyrosine, and phenol).

98 e humidity was also observed for uptake onto humic acid, with larger uptake coefficients seen at high

99 of site masking in the ternary clay mineral-humic acid-bacteria composite.

100 in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic c

101 ological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discuss

102 onic species to low proton-affinity sites in humic acid.

103 e shoot growth-promoting action of the model humic acid.

104 rt from the aerosols from the two sources of humic acid.

105 t hydraulic conductivity caused by the model humic acid.

106 by coating silica particles with commercial humic acid.

107 edia of quartz sand, even in the presence of humic acid.

108 the presence of thiol compounds and natural humic acid.

109 f the photosensitizers nitrate, nitrite, and humic acid.

110 of a real HS sample, the standard Leonardite humic acid.

111 Stability study of AgNPs, formed in Ag(+)-humic acid/fulvic acids-Fe(3+) mixtures over a period of

112 samples was compared to dissolved commercial humic acids (DOM).

113 Humic acids (HA) compete with TCs for Fe(II), but the ef

114 Sunflower root exudates, humic acids (HA), and the synthetic oleophilic fertilize

115 hodes were exposed to high concentrations of humic acids (HA).

116 indicated that an increase in the amount of humic acids (HAs) increasingly inhibited Al adsorption b

117 We report how adsorption of three different humic acids (HAs) to redox-inert sorbents (polar Al(2)O(

118 of TBBPA bound-residue formation to two soil humic acids (HAs), Elliott soil HA and Steinkreuz soil H

119 er considerably in their reaction rates with humic acids (k (sulfate radical + humic acids) = 6.8 x 1

120 fer from reduced and nonreduced Pahokee Peat humic acids (PPHA) and fresh soil organic matter (SOM) e

121 borohydride-reduced Suwanee River fulvic and humic acids (SRFA and SRHA, respectively).

122 including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isol

123 isporus serine proteinase SPR1 is induced by humic acids and is highly expressed during growth on com

124 s similar to the behavior observed for model humic acids and several surface waters, suggesting that

125 e in pH enhanced the formation of AgNPs, and humic acids as ligands showed higher formation of AgNPs

126 The value of logK (ratio of absorbance of humic acids at 400 and 600 nm) was cedar > transition zo

127 with Elliott humic and fulvic acids and with humic acids extracted from natural carbonaceous material

128 It was further observed that humic acids generally react faster than fulvic acids.

129 The binding of Pb(II) to humic acids is studied through an approach combining equ

130 FeOx associated with humic acids or citrate were less toxic than OM-free FeOx

131 (13)C-CP/MAS NMR measurements of humic acids revealed an increasing incorporation of phen

132 The high reactivity of humic acids toward HO(*) is in line with the antioxidant

133 -1) (mgC = mg carbon); k (hydroxyl radical + humic acids) = 1.4 x 10(4) L mgC(-1) s(-1)).

134 rates with humic acids (k (sulfate radical + humic acids) = 6.8 x 10(3) L mgC(-1) s(-1) (mgC = mg car

135 tles (confirmed by replacing the sludge with humic acids), and (iii) Geobacter sulfurreducens to prod

136 Thus, in the presence of humic acids, atrazine is degraded more efficiently by su

137 t environmental particles such as fulvic and humic acids, practical strategies are delineated for det

138 ot able to exchange electrons with dissolved humic acids, the procedure allows an accurate and reliab

139 eshwater and coastal seawater are fulvic and humic acids.

140 Zn in solution is mainly bound to dissolved humic acids.

141 terial than with Nordic NOM and Pahokee peat humic acids.

142 binding sites on larger, less bioaccessible humic acids.

143 l radical, as well as indigenous radicals of humic acids.

144 The presence of the humic adlayers on solid supports was shown to significan

145 atively small in comparison to large mass of humics adsorbed.

146 sess the average molecular weight of various humic and fulvic acid isolates as model DOM, using liter

147 xhibiting trends also observed for reference humic and fulvic acid isolates.

148 these fractions are not retained in typical humic and fulvic acid isolation procedures that use XAD

149 n cysteine solutions but not in DI water, or humic and fulvic acid solutions.

150 al organic matter (NOM, i.e., Suwannee River Humic and Fulvic Acid Standards and Pony Lake Fulvic Aci

151 nt types of NOM were studied: Suwannee River humic and fulvic acids (SRHA and SRFA) and alginate.

152 (from 0 to 40 mg C L(-1)) for Suwannee River humic and fulvic acids and Pony Lake fulvic acid.

153 This process is more important with Elliott humic and fulvic acids and with humic acids extracted fr

154 and HOBr increased the sorption tendency of humic and fulvic acids to the hydrophobic surface with m

155 proteins, polysaccharides, fatty acids, and humic and fulvic acids with a model hydrophobic surface

156 er samples was similar to that observed with humic and fulvic acids, pointing to the importance of th

157 s of dissolved organic matter (DOM), such as humic and fulvic acids, proteins, polysaccharides, and l

158 adlayers formed from a diverse set of eight humic and fulvic acids, used as DOM models, on surfaces

159 The samples were dominated with humic and lignin-like components, and enriched with amin

160 hile a smaller fraction originated from soil humics and appears to be photochemically or microbially

161 ionated by both hydrophobicity (bulk and non-humic) and apparent molecular weight (AMW).

162 lecular properties for each of the classical humic- and protein-like FDOM components are presented.

163 artition coefficients (Kd) between water and humics-coated silica gels after 10 days exposure reached

164 the sequestered Pu was remobilized from the humics-coated silica gels by treatment with dissolved hu

165 of water-borne plutonium (up to 73%) on the humics-coated silica gels.

166 Within the catchment, humic colloids lost up to 50% of their copper-binding ca

167 at different depths in a column of strongly humic-colored [i.e., solar ultraviolet (UV)-attenuating]

168 mechanisms likely affect stepwise elution of humic components from XAD-8 resin with pyrophosphate buf

169 ecules enables structure characterization of humic compounds.

170 his relationship is globally representative, humics could impose a concentration threshold that buffe

171 This study highlights the dearth of humic data, and the immediate need to measure electroact

172 formed in situ using self-adhesive silanized humic derivatives.

173 tory spiders and scorpions, parasitic ticks, humic detritivores, and marine sea spiders (pycnogonids)

174 the immediate need to measure electroactive humics, dissolved iron and iron-binding ligands simultan

175 To evaluate such humic DOM influences, we characterized the optical prope

176 ent with three independent components in the humic fluorescence response, which are assigned to moiet

177 the leachates identified a distinctive soil humic fluorophore observed in all samples and fluorescen

178 ed by fractionation in operationally defined humic, fulvic, and hydrophilic acid pools under various

179 leaf litter-extracted DOM and Suwannee River Humic/Fulvic Acid (SRHA/SRFA) and have sorptive preferen

180 s modeled using three approaches: binding to humic/fulvic acids, binding to thiol-groups, or a combin

181 open ocean sites, with the ratio of iron to humics increasing with depth.

182 Addition of a humic isolate increased lead release due to uniform corr

183 Humic lakes and pools are the primary receptacles for te

184 t and anoxic hypolimnion water layer of five humic lakes in WI, USA.

185 e and community structure of algae in upland humic lakes of Ireland and Northern Ireland, despite lon

186 om May to August in 2003 and 2008 from three humic lakes using terminal restriction fragment length p

187 Three humic lakes were sampled weekly May-August and correlati

188 Our results agree with humic ligands composing a large fraction of the iron-bin

189 by the concentration and binding capacity of humic ligands, and provide a summary of the key processe

190 analysis supported a two-component model of humic-like and nonhumic-like dissolved organic matter (D

191 concentration of 1.09 mug/L, identified two humic-like and two previously reported oil-like componen

192 O2 advanced oxidation, transformation of the humic-like components was slower than that of the trypto

193 Significantly, the quenched fluorescence of humic-like DOM (static and/or dynamic quenching) by nonh

194 associated with decreased amounts of natural humic-like DOM and enriched amounts of anthropogenic ful

195 and was related to decreasing proportions of humic-like DOM and increasing proportions of protein-lik

196 organic matter at tryptophan-like (TLF) and humic-like fluorescence (HLF) peaks is associated with t

197 Humic-like fluorescence (peaks A and C) was selectively

198 snow (R(2) = 0.31) and a decrease in percent humic-like fluorescence (R(2) = 0.36), indicating an ove

199 c carbon concentrations were correlated with humic-like fluorescence indexes.

200 ound in wastewater effluent, indicating that humic-like fluorescence is associated with different com

201 scence indexes that correspond to a group of humic-like fluorescing species were determined to be hig

202 Fluorescence intensity of a humic-like fluorophore (i.e., I345/425) correlated stron

203 ike fluorophore and preferentially removed a humic-like group irrespective of the coagulant.

204 amples with the predominant components being humic-like in river water, but protein-like in a highly

205 reference streams is exported in the form of humic-like material with high molecular weight, which in

206 etween diesel-like material and more complex humic-like material.

207 ll U colloids; a 1-3 kDa fraction containing humic-like organic compounds, dispersed Fe, and, to a sm

208 ously considered of terrestrially-derived or humic-like origin published in the OpenFluor database.

209 ent through increased levels of a microbial, humic-like parallel factor analysis component (C6).

210 polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the

211 mass burning, model comparisons suggest that humic-like substances (HULIS) contribute to ROS formatio

212 (water-soluble organic carbon, WSOC) and the humic-like substances (HULIS) fraction of WSOC.

213 Humic-like substances (HULIS) in particulate matter such

214 es, and potentially explaining one source of humic-like substances (HULIS) ubiquitously present in at

215 Humic-like substances (HULIS), a complex mixture of amph

216 Humic-like substances (HULIS), extracted from atmospheri

217 re abundant photosensitizer species, such as humic-like substances (HULIS), may contribute more signi

218 he OA components contributing to WS_DTT were humic-like substances (HULIS), which are abundantly emit

219 y unresolved compounds, often referred to as humic-like substances (HULIS), which influence particle

220 pically identified in the complex mixture of humic-like substances (HULIS).

221 th absorptions and oxidation consistent with humic-like substances (HULIS).

222 Recently, it has been determined that humic-like substances and unknown organic chromophores a

223 Ligands within humic-like substances have long been considered importan

224 izer chemistry of humic acid, as a proxy for humic-like substances in atmospheric aerosols, to contri

225 Humic-like substances were the dominant organic fraction

226 captured by common classifications such as "humic-like" fluorescence.

227 show that (1) EEM-PARAFAC fitted terrestrial humic-like, anthropogenic humic-like, tryptophan-like, a

228 fitted terrestrial humic-like, anthropogenic humic-like, tryptophan-like, and tyrosine-like component

229 Consequently, silanized humic materialas can be seen as both molecular probes an

230 ated silica gels by treatment with dissolved humic materials at environmentally relevant pH of 7.5.

231 ium partitioning between immobile and mobile humic materials at the water-solid interfaces.

232 Immobilization of the humic materials on solid supports was performed in situ

233 id birnessite) interactions with and without humic matter (HM) via batch experiments.

234 ute of Cr(VI) formation which is tempered by humic matter.

235 characterized by a high fraction of aquatic humic matter.

236 n chromium-NOM complexation in the Stockholm Humic Model (SHM): a monomeric complex dominated at pH <

237 Two humic moieties and a protein-like group were identified

238 ncluding binding between groups of different humic molecules, promoting aggregation; further metal io

239 stem-offers exciting insight into studies of humic/nonhumic interactions with important implications

240 ng season in two contrasting boreal lakes, a humic oligotrophic lake and a clear-water productive lak

241 enzyme in the adaptation of Agaricus to the humic-rich ecological niche formed during biomass degrad

242 aptation, persistence and growth of fungi in humic-rich environments such as soils of temperate woodl

243 compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present

244 l lower absolute lignin phenol yields in the humic-rich lake water samples upon C18 extraction.

245 water samples, a fresh leaf leachate and two humic-rich lake waters, were analyzed by the direct meth

246 rient-poor, low-sediment, high-transparency, humic-stained, acidic blackwaters; (2) nutrient-poor, lo

247 Microbial humic substance (HS) reduction and subsequent abiotic el

248 red HDA quenching rate constants for various humic substance isolates and whole waters with singlet o

249 solates such as those from the International Humic Substance Society (IHSS), wide-ranging values exis

250 fulvic acids purchased by the International Humic Substance Society.

251 Humic substances (HS) acting as photosensitizers can gen

252 Humic substances (HS) are abundant in the environment an

253 es of phenol electron donors to solutions of humic substances (HS) enhanced substantially the initial

254 Humic substances (HS) found in the SR dominated the comp

255 Natural organic matter and humic substances (HS) in soils and sediments participate

256 yses have shown that the chlorination of the humic substances (HS) in the presence of high H3O(+) and

257 mophoric dissolved organic matter (CDOM) and humic substances (HS) remains poorly understood and yet

258 influence of different fractions of aquatic humic substances (HS) was evaluated.

259 he redox and photochemical properties of the humic substances (HS), the relationship between these ch

260 ification of the fraction of Fe complexed to humic substances (HS).

261 ating the high stability of peatland-derived humic substances (HS).

262 Humic substances (HSs) are important electron acceptors

263 ioxamine B (DFOB) on Fe removal from aquatic humic substances (XAD-8-isolated) and other organic matt

264 ion on the optical properties of a series of humic substances and a lignin model were examined to pro

265 Fe bound to humic substances and other more "transphilic" organic co

266 ed in surface peat explained by variation in humic substances and phenolics.

267 istic source of the natural organobromine in humic substances and the soil organic horizon.

268 e with pollutants based on properties of the humic substances are possible.

269 e we show iron co-varying with electroactive humic substances at multiple open ocean sites, with the

270 oethite nanoparticles with and without added humic substances demonstrates that, in all cases, humic

271 d phosphorus (P) is increasingly adsorbed to humic substances in this enrichment zone.

272 or dual fluorescing peaks in amino acids and humic substances is postulated.

273 OM isolates purchased from the International Humic Substances Society ranged from 16 to 34 kJ mol(-1)

274 Using International Humic Substances Society standards, Suwannee River fulvi

275 Similar behavior with humic substances suggests that they and BrC share a comm

276 substances demonstrates that, in all cases, humic substances suppressed Fe(II)-goethite reactivity.

277 While humic substances tend to decrease aggregation and deposi

278 ion in the presence and absence of different humic substances that significantly enhance the chloroth

279 carbon specific iron-binding capacity of the humic substances which was [L]/[Corg] = (0.80 +/- 0.20)

280 e redox properties of traditionally defined "humic substances".

281 tion of large-molecular-size and persistent 'humic substances' in soils.

282 Soil components (e.g., clays, bacteria and humic substances) are known to produce mineral-organic c

283 lity include complexation of As by dissolved humic substances, and competitive sorption and electron

284 Humic substances, polysaccharides, and proteins present

285 Humic substances, the main component of soil organic mat

286 oxybenzoic acid, as models for structures in humic substances, we found significantly higher formatio

287 nteract with natural organic matter (NOM) or humic substances, which will change their fate and trans

288 minescence evolution of Eu(III) complexed by humic substances--that is, the increase of the asymmetry

289 s been surprisingly little-employed to study humic substances.

290 tified in the presence of well-characterized humic substances.

291 mainly driven by the quantity and quality of humic substances.

292 soil fulvic acid, an operational fraction of humic substances.

293 ototransformation and the photoreactivity of humic substances.

294 own to react by energy transfer from excited humic substances.

295 upramolecular assemblies thought to exist in humic substances.

296 four components were identified as microbial humic-, terrestrial humic-, tyrosine-, and tryptophan-li

297 tion and to energy transfer from the triplet humic to ground state chlorothalonil.

298 ifferent DOMs, from a high-colored DOM (more humic) to a low-colored DOM (less humic).

299 identified as microbial humic-, terrestrial humic-, tyrosine-, and tryptophan-like fluorescent signa

300 ation of colloids in boreal Fe- and DOM-rich humic waters (a stream and a fen).