Minor Bands Research Articles

Photoexcitation Dynamics of Cyanate‐ligated Ferric Heme Proteins Probed by Femtosecond Vibrational Spectroscopy#

The photoexcitation dynamics of cyanate‐ligated ferric myoglobin (MbNCO) and hemoglobin (HbNCO) in D2O at 293 K after excitation with a visible pulse was investigated by probing the anti‐symmetric stretching (ν1) mode of the NCO − ion bound to Mb or Hb using femtosecond vibrational spectroscopy. The ν1 mode of NCO in MbNCO or HbNCO in D2O shows one absorption feature near 2158 cm−1, which is similar to that of the free anion in D2O (2160 cm−1). The absorption feature of MbNCO was described by two absorption bands, i.e., one major band (90%) peaked at 2157 cm−1 with a full width at half maximum (FWHM) of 11 cm−1 and a minor band (10%) at 2143 cm−1 with an FWHM of 12 cm−1. In HbNCO, the major (82%) and minor (18%) bands are at 2159 (FWHM of 14 cm−1) and 2145 cm−1 (FWHM of 14 cm−1), respectively. The major and minor bands were attributed to the high‐ and low‐spin heme complexes, respectively. The photoexcited MbNCO and HbNCO undergo a rapid electronic relaxation with a time constant smaller than 0.4 ps, followed by thermal relaxation with a time constant of 8 ± 1 ps. No measurable absorption band for the photodeligated NCO − was detected, indicating that the photodeligation quantum yield of NCO −‐bound ferric heme proteins is negligible. The characteristics of the thermal and electronic relaxations are independent of both the excitation wavelengths used (575 and 400 nm) and heme proteins probed (Mb and Hb). Although the interaction between the cyanate and Fe3+ of the heme in Mb and Hb may be weak as suggested by the negligible shift in the band position of the cyanate upon ligand binding, the photodissociation of NCO − by a visible pulse is not significant. This finding is consistent with the negligible photodeligation observed for most of the other anion‐ligated ferric heme proteins.

Purification and identification of an antibacterial protein from the symbiotic bacteria associated with novel entomopathogenic nematode, Rhabditis (Oscheius) sp.

Entomopathogenic nematodes (EPN) belonging to the families steinernematidae and heterorhabditidae and their symbiotic bacteria Xenorhabdus and Photorhabdus are well-known as biological control agents and are found to produce a wide range of bioactive secondary metabolites. Studies carried out at the Central Tuber Crops Research Institute (CTCRI) on entomopathogenic nematodes resulted in the identification of novel EPN belonging to the family Rhabditidae. This study reports the purification of a high molecular weight antibacterial protein from culture filtrates of a bacterium (Bacillus cereus) symbiotically associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species, maintained at CTCRI laboratory. Fermentation conditions were standardized and optimum antibacterial activity was observed in tryptic soy broth after 48h incubation at 30°C. The aqueous extracts yielded antibacterial proteins which were purified by ammonium sulfate precipitation followed by ion exchange chromatography and size exclusion chromatography. Native gel electrophoresis indicated an active protein of molecular mass 220KDa which resolved into a major band of 90kDa and a minor band of about 40kDa on SDS-PAGE. The 90kDa protein showed antibacterial activity and was further analysed by MALDI TOF-MS/MS. The protein was identified as a TQXA (Threonine-glutamine dipeptide) domain containing protein from Bacillus cereus. The protein was found to be active against Bacillus subtilis MTCC2756, Staphylococus aureus MTCC902 and Escherichia coli MTCC 2622 and was thermally stable.

Transient band structures in the ultrafast demagnetization of ferromagnetic gadolinium and terbium

We compare the laser-driven demagnetization dynamics of the rare earths gadolinium and terbium by mapping their transient valance band structures with time- and angle-resolved photoelectron spectroscopy. In both metals, the minority and majority spin valence bands evolve independently with different time constants after optical excitation. The ultrafast shift of the partially unoccupied minority spin bulk band to higher binding energy and of the majority spin surface state to lower binding energy suggests spin transport between surface and bulk. The slower response of the fully occupied majority spin band follows the lattice temperature and is attributed to Elliott-Yafet type spin-flip scattering. Terbium shows a stronger and faster decay of the exchange splitting, pointing to ultrafast magnon emission via $4f$ spin-to-lattice coupling.

Enzymatic Digestion and Mass Spectroscopies of N-Linked Glycans in Lacquer Stellacyanin fromRhus vernicifera

Lacquer stellacyanin was isolated and purified from lacquer acetone powder by continuous Sephadex column chromatographies using Sephadex C-50, DEAE A-50, and C-50 gels. The purified lacquer stellacyanin had a blue color with one major and three minor bands around 26 k Dain SDS PAGE. Trypsin- and chymotrypsin-treated lacquer stellacyanins were examined by LC/MS/MS to determine three N-glycosylation sites (N28, N60, and N102) and were further analyzed by MALDI TOF MS, indicating that the N-linked glycans were attached to the three asparagine (Asn) sites, respectively. In addition, after trypsin digestion and PNGase A and PNGase F treatments to cleave N-linked glycans from the Asn sites, it was found that lacquer stellacyanin had a xylose containing a biantennary N-linked glycan with core fucosylation consisting of 13 sugar residues (a complex type N-linked glycan) by MALDI TOF MS analysis. This is the first report on the structure of an N-linked glycan in lacquer stellacyanin.

Viperatoxin-II: A novel viper venom protein as an effective bactericidal agent

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have become a rising threat to public health. There is an urgent need for development of promising new therapeutic agents against drug resistant bacteria like S. aureus. This report discusses purification and characterization of proteins from Indian Russell’s viper snake venom. Novel 15-kDa proteins called “Viperatoxin” (VipTx-I and VipTx-II) were extracted from the whole venom and evaluated using in vitro antimicrobial experiments. The N-terminal amino acid sequence of “Viperatoxin” showed high sequence homology to daboiatoxin isolated from the same venom and also matched phospholipase A2 (PLA2) enzymes isolated from other snake venoms. In an in vitro plate assay, VipTx-II but not VipTx-I showed strong antimicrobial effects against S. aureus and Burkholderia pseudomallei (KHW & TES), Proteus vulgaris and P. mirabilis. The VipTx-II was further tested by a broth-dilution assay at 100–3.125μg/ml concentrations. The most potent bactericidal effect was found at the lowest dilutions (MICs of 6.25μg/ml) against B. pseudomallei, S. aureus and P. vulgaris (MICs of 12.25μg/ml). Electron microscopic investigation revealed that the protein-induced bactericidal potency was closely associated with pore formation and membrane damage, even at the lowest concentrations (<20μg/ml). The toxin caused a low level of cytotoxic effects as observed in human (THP-1) cells at higher concentrations. Molecular weight determinations of VipTx-II by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed one major, along with a few minor bands. The results indicate that VipTx-II plays a significant role in bactericidal and membrane damaging effects in vitro. Non-cytotoxic properties on human cells highlight it as a promising candidate for further evaluation of antimicrobial potential in vivo.

Polyacrylamide gel electrophoresis of soybean seed proteins

Four major and 14 minor protein bands were detected when total salt soluble proteins of soybean (Glycine max cultivar Warszawska) seed were subjected to polyacrylamide gel electrophoresis under nondissociating conditions, and 16 protein bands were detected under dissociating conditions. Molecular weights of three major protein fractions in PAGE SDS were determined for around 18 500, 36 000 and 80 000 daltons.

Switching of the photophysical properties of Bodipy-derived trans bis(tributylphosphine) Pt(II) bisacetylide complexes with rhodamine as the acid-activatable unit.

A rhodamine moiety was used for the preparation of trans bis(tributylphosphine) Pt(II) bisacetylide complexes (RH-BDPY-Pt-1 and RH-BDPY-Pt-2, with two different Bodipy acetylide ligands), which show acid/base-switchable photophysical properties. The rhodamine moiety undergoes reversible spirolactam ↔ opened amide structure transformation in the presence of an acid/base. Bodipy ligands are responsible for strong visible light-harvesting. The photophysical properties of the Pt(II) complexes were studied with steady state UV-Vis absorption, luminescence spectra, nanosecond transient absorption spectroscopy, electrochemical characterization and DFT/TDDFT computations. In the absence of an acid, the complexes show the absorption of Bodipy ligands at 580 nm and 500 nm, respectively. Both complexes show fluorescence. A minor phosphorescence band was observed for RH-BDPY-Pt-1. In the presence of trifluoroacetic acid (TFA), the spirolactam → opened amide transformation occurred and the absorption of the rhodamine moiety at 570 nm appeared; colour changes were observed for the solutions of the complexes. Moreover, the fluorescence of the complexes was switched on. Long-lived triplet excited states were observed for the two complexes (35 μs and 423 μs, respectively, in dichloromethane). Upon the addition of TFA, the triplet state lifetime of RH-BDPY-Pt-1 was substantially prolonged to 80 μs from 35 μs (the triplet state of RH-BDPY-Pt-1 is localized on the Bodipy moiety); for RH-BDPY-Pt-2, however, the triplet state is switched from the Bodipy-confined triplet state to a triplet state delocalized on the Bodipy and rhodamine moiety. Thus both the singlet excited state and the triplet state of the Pt(II) complexes were switched upon the addition of an acid. The photophysical properties were rationalized with DFT/TDDFT calculations. These results on tuning of the photophysical properties of Pt(II) complexes with a rhodamine moiety may be useful for designing external stimuli-activatable transition metal complexes.

Absorption and Emission Sensitivity of 2-(2'-Hydroxyphenyl)benzoxazole to Solvents and Impurities.

2-(2'-Hydroxyphenyl)benzoxazole (HBO) is known for undergoing intramolecular proton transfer in the excited state to result in the emission of its tautomer. A minor long-wavelength absorption band in the range 370-420 nm has been reported in highly polar solvents such as dimethylsulfoxide (DMSO). However, the nature of this species has not been entirely clarified. In this work, we provide evidence that this long-wavelength absorption band might have been caused by base or metal salt impurities that are introduced into the spectral sample during solvent transport using glass Pasteur pipettes. The contamination by base or metal salt could be avoided by using borosilicate glass syringes or nonglass pipettes in sample handling. Quantum chemical calculations conclude that solvent-mediated deprotonation is too energetically costly to occur without the aid of a base of an adequate strength. In the presence of such a base, the deprotonation of HBO and its effect on emission are investigated in dichloromethane and DMSO, the latter of which facilitates deprotonation much more readily than the former. Finally, the absorption and emission spectra of HBO in 13 solvents are reported, from which it is concluded that ESIPT is hindered in polar solvents that are also strong hydrogen bond acceptors.

Simultaneous detection and discrimination of Pratylenchus and Meloidogyne species in Japanese fields using group-specific primers and denaturing gradient gel electrophoresis

We developed a simultaneous detection and discrimination method for the main Pratylenchus and Meloidogyne species of nematodes inhabiting Japanese fields. The method consists of a single polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) process using group-specific primers (SNem 1–4) constructed from the 18S rDNA region with high specificity toward these nematodes. Optimal electrophoresis conditions to differentiate PCR products of each species were 60 °C at a constant voltage of 70 V for 17 h using DGGE gel, with a 6 % acrylamide concentration and a denaturant gradient ranging from 25 to 41 %. Differentiation of most species was achieved according to their main band positions. Only bands derived from the Pratylenchus and Meloidogyne species were present in the DGGE profiles of many nematode communities from various locations in Japan, so we concluded that these primers were sufficiently specific to the targeted nematodes. Detection sensitivity was so high that we could detect one second-stage juvenile of Pratylenchus species among 1,000 free-living nematodes using a single PCR step (35 cycles). Even when two or more target species coexisted in a community, we could usually detect and distinguish them accurately. Most target species formed some minor bands in addition to the primary band. Any interference of the minor bands with the main bands of other target species was overcome using optimal denaturing gradient conditions for the electrophoresis.

Density functional study of half-metallic property on B2 disordered Co2FeSi

First principle calculations on the magnetic properties and spin polarization of the B2 disordered Co2FeSi full Heusler alloy have been carried out along with that of ordered L21 structure. The linear augmented plane wave method, within the LDA+U approximation, gives the magnetic moment value as predicted by Slater-Pauling rule. A small band gap in the minority band structure around the vicinity of the Fermi level results in half-metallicity or 100 % spin polarization in L21 ordered structure. The calculations also showed that the half-metallicity vanishes at moderate percentages of B2 disorders due to creation of new states around the Fermi level in the minority DOS but at low and high levels of disorder, the half-metallicity was retained. The variation in the magnetic moments of Co2FeSi with change in the % disorder was attributed to the changes in the local magnetic moments of Co, Fe, and Si atoms which vary with change in % disorder.

Quantification of fluorite mass-content in powdered ores using a Laser-Induced Breakdown Spectroscopy method based on the detection of minor elements and CaF molecular bands

Laser Induced Breakdown Spectroscopy (LIBS) is investigated as a fast and robust method to determine the fluorite (CaF2) mass-content of powdered ore samples. Calibrating samples covering a wide CaF2 concentration range (from 2.3 to 97.6%) are employed. LIBS operating conditions are optimized for the analysis of elemental emission lines and molecular bands, respectively. In particular, LIBS emission intensities from different CaF molecular bands are evaluated to calibrate the fluorite concentration as an alternative to the use of atomic fluorine F I emission lines. Furthermore, the determination of LIBS emission signals from minor elements (e.g. Si I and Mg I) is studied to further improve the accuracy and precision of pure fluorite sample analyses (e.g. [CaF2]>75%). The proposed LIBS method avoids the tedious dissolution processes that are required by other analytical methods employed in mining industry for the quantitative analysis of fluorite.

Pollution, habitat loss, fishing, and climate change as critical threats to penguins.

Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large-scale conservation zones are not always practical or politically feasible and other ecosystem-based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales.

MONITORING OF SALT TOLERANCE RESPONSES OF DIFFERENT MAIZE INBRED LINES USING PROTEIN PROFILE AND PROTEIN SPECTROFLUORESCENCE

Seedlings of Six maize inbred lines CML 511, CML 448, CML 444, CML 395, CML 254 and CML 216 were used to analyze salt stress of (150 mM NaCl). The analyses of RAPD results showed 84.6% of polymorphic fragments. Accessions of CML 511 and CML 448 were included in one main cluster with genetic similarity of 0.65. The genetic similarity between CML 444 and CML 395 was 0.72, the other accessions of CML 254 and CML 216 had genetic similarities of 0.67 and 0.62, respectively. Leaf proteins were studied by one-dimensional SDS-PAGE. Under non stress conditions, the minor band of 45 kDa was not expressed in varieties of CML 254 and CML 216 while band of 23 kDa were expressed in all accessions except of CML 216 accession. Under stress conditions high molecular weight bands were disappeared and the major protein bands were located at the medium molecular weight range. Protein spectrofluorescence of leaf protein samples show main emission peak at about 320 nm in both conditions of salt stress and control. However, the emission intensities showed some variations among different maize lines in alternative conditions of control and salt stress. This might be referred to change in protein interactions. Inbred lines of CML 511 and CML 448 exhibit closely related fluorescence pattern, this is in context of their genetic similarities as has deduced by RAPD results.

Contact Metamorphism of Precambrian Gneiss by the Skaergaard Intrusion

The Tertiary Skaergaard intrusion, East Greenland, intruded at the shallow crustal unconformity between Precambrian amphibolite-facies gneisses and overlying Tertiary Plateau Basalts. Maximum contact metamorphic temperatures in quartzo-feldspathic gneisses were determined in two sample traverses across the aureole on the western contact of the intrusion using a combination of microstructural observations (both optical and cathodoluminescence) and the titanium-in-quartz (TitaniQ) thermometer. The onset of recrystallization of the quartz in the gneisses occurred between 390 and 340 m from the contact whereas H2O-fluxed melting occurred in gneisses closer than 130 m from the contact (where T > ∼ 675°C). The maximum temperature recorded by quartz at the contact is ∼865 ± 70°C. Melt fractions reach 50–60 vol. % in some samples although the melt is heterogeneously distributed on all scales. Minor bands of amphibolite-facies mafic gneiss are extensively reacted to an anhydrous pyroxene-bearing hornfels close to the contact, whereas those further than ∼130 m are overprinted by a greenschist-facies assemblage. Discrepancies between the expected temperature for the amphibolite- to greenschist-facies reaction and temperatures obtained from adjacent quartzo-feldspathic gneisses are consistent with the formation of the anhydrous pyroxene hornfels directly from the mafic gneiss, with the lower-grade greenschist-facies assemblage forming on the retrograde path after the establishment of limited hydrothermal activity. It is unlikely that devolatilization reactions in the gneiss produced sufficient H2O to account for the pegmatitic features formed in the Marginal Border Series in the intrusion. A simple one-dimensional thermal model, neglecting any advection of heat by hydrothermal circulation, was fitted to the profile of maximum temperature through the aureole. The generally lower temperatures seen in the gneiss compared with those previously reported for the contact metamorphosed basalts higher up the walls of the intrusion are consistent with a heterogeneous release of latent heat of crystallization.

The role of Co atoms in spin dependent electronic properties of graphite-like ZnO structures

A first principles study is employed to reveal the electronic properties of graphite-like Co doped ZnO structures composed of atomic layers when spin property of electrons is involved. The influence of Co atoms, which are substituting the Zn atoms, was addressed through distinct atomic arrangements formed by specific atomic configurations and various Co concentrations. We obtained that the spin dependent behavior is largely determined by the atomic arrangement which can crucially impact the electronic structure for a certain spin orientation. It was observed that atomic configuration is an essential factor which may reduce or enhance the minority-spin energy gap relative to majority one. It was shown that the emerging spin polarization can be manipulated by the atomic arrangement of the layered structures. Both the spin polarization and the magnetic moment were found to be contributed by both Co and O atoms. The stability of a system via formation energy, the role of Co dopants positioned at different Zn sites, the number of both Co atoms and layers in a supercell, and the mechanisms governing the spin dependent behavior of these structures are discussed. • Co dopants at distinct locations yield crucial changes in spin dependent behavior. • Spin dependent behavior is determined by atomic arrangement in Co doped ZnO systems. • Atomic configuration and Co concentration play a crucial role on minority band gap. • The magnetic moment is mostly contributed by Co-3d and O-2p orbitals.

Spin-polarized transport properties of GdN nanocontacts

Gadolinium nitride (GdN) nanocontacts were recently experimentally shown to be efficient spin filters. Our study is aimed at identifying and analyzing the physical processes responsible for the high spin polarization of the tunneling current in GdN nanostructures. By the example of planar contacts and atomic chains attached to Cu electrodes we assert, using first principle techniques, that a 100% spin-filtering effect can be indeed achieved in GdN nanocontacts. Our analysis shows that the spin filtering is due to the predominant role of nitrogen majority $p$ states in the electron transport, while minority conductance decays exponentially with contact size due to the presence of a minority band gap at the Fermi level. Additionally, GdN zigzag infinite chains are found to be as efficient spin filters as their planar contact counterparts, also exhibiting a 100% spin-filtering effect, which is robust against chain geometry changes.

Anticoagulation activity of salivary gland extract of oriental blackfly Simulium indicum

To study the morphology of the salivary gland of the female blackfly of the species Simulium indicum (S. indicum) along with protein profile and anticoagulant activity of the salivary gland extract. Sodium dodecyl sulphate polyacrylamide gel electrophoresis was used to analyze the protein profile of the salivary gland extract (SGE) and anticoagulant activities against thrombin, and the extrinsic and intrinsic coagulation pathways were found in S. indicum SGE in the TT, PT and APTT assays, respectively. Results revealed that each gland consisted of a cylindrical U-shaped secretory lobe and a more or less spherical reservoir. The protein contents of whole salivary glands were also quantified and the amount of salivary gland proteins in the adult female S. indicum was found out to be approximately 1.12±0.13 µg/female. At least 16 major and several minor protein bands were detected in the female salivary glands. The molecular masses of these major protein bands were estimated at 69, 65, 61, 58, 44, 42, 39, 33, 30, 28, 27, 26, 23, 21, 18 and 16 kDa, consecutively. Anticoagulant activities were found in S. indicum SGE in all the assays. It was found that SGE prolonged human plasma clotting time in a dose-dependent manner. Factor Xa inhibition was shown by the SGE of S. indicum. Percent inhibition value was 93.8. A positive correlation (r=0.89) was observed between total protein and percent inhibition of factor Xa. The present study demonstrated that the mode of action of the anticoagulant(s) is mainly on the inhibition of thrombin and factor Xa along with other target factors of the coagulation cascade.

Interaction of iron phthalocyanine with the graphene/Ni(111) system.

Graphene grown on crystalline metal surfaces is a good candidate to act as a buffer layer between the metal and organic molecules that are deposited on top, because it offers the possibility to control the interaction between the substrate and the molecules. High-resolution angular-resolved ultraviolet photo electron spectroscopy (ARPES) is used to determine the interaction states of iron phthalocyanine molecules that are adsorbed onto graphene on Ni(111). The iron phthalocyanine deposition induces a quenching of the Ni d surface minority band and the appearance of an interface state on graphene/Ni(111). The results have been compared to the deposition of iron phthalocyanine on graphene/Ir(111), for which a higher decoupling of the organic molecule from the underlying metal is exerted by the graphene buffer layer.

Understanding the Zero-Strain Lithium Insertion Scheme of Li[Li1/3Ti5/3]O4: Structural Changes at Atomic Scale Clarified by Raman Spectroscopy

Lithium titanium oxide Li[Li1/3Ti5/3]O4 (LTO) is regarded as an ideal electrode material for lithium-ion batteries because of its “zero-strain” characteristic, high thermal stability, and structural stability. Here, the zero-strain means that the change in cubic lattice parameter is negligibly small during charge and discharge reactions. We performed ex situ Raman spectroscopy on Li1+x[Li1/3Ti5/3]O4 samples with 0 ≤ x ≤ 0.94 to gain information about the relationship between a zero-strain reaction scheme and structural change at the atomic scale. The x = 0 (initial) sample exhibits three major Raman bands at 671, 426, and 231 cm–1 and six minor Raman bands at 751, 510, 400, 344, 264, and 146 cm–1. According to Raman spectroscopy results on other lithium titanium oxides such as Li2TiO3 and TiO2, the Raman bands at 510, 400, and 146 cm–1 are attributed to TiO2 anatase, which is used as a starting material. As x increases from 0 to 0.94, the two major Raman bands at 426 and 231 cm–1 show a blue shift, while the major Raman band at 671 cm–1 maintains frequency. The three major Raman bands at 671, 423, and 231 cm–1 are assigned to the A1g mode of symmetric stretching vibration νsym(Ti–O), the Eg mode of asymmetric stretching vibration νasym(Li–O), and the F2g mode of bending vibration δ(Ti–O), respectively. Thus, the change in the Raman spectrum with x indicates that the bond length between the Ti and O atoms in the TiO6 octahedron is independent of x, while that between the Li and O atoms in the LiO6 octahedron and the bond angle between the Ti and O atoms in the TiO6 octahedron change with x. Raman studies with decreasing x from 0.94 to 0.10 clarified that such local structural changes are reversible, as in the case for the electrochemical reaction. The zero-strain insertion scheme is discussed from the perspective of Raman spectroscopy.

Configuration-dependent electronic and magnetic properties of graphene monolayers and nanoribbons functionalized with aryl groups.

Graphene monolayers functionalized with aryl groups exhibit configuration-dependent electronic and magnetic properties. The aryl groups were adsorbed in pairs of neighboring atoms in the same sublattice A (different sublattices) of graphene monolayers, denoted as the M2 (AA) (M2 (AB)) configuration. The M2 (AA) configuration behaved as a ferromagnetic semiconductor. The band gaps for the majority and minority bands were 1.1 eV and 1.2 eV, respectively. The M2 (AB) configuration behaved as a nonmagnetic semiconductor with a band gap of 0.8 eV. Each aryl group could induce 1 Bohr magneton (μB) into the molecule-graphene system. Armchair graphene nanoribbons (GNRs) exhibited the same configuration-dependent magnetic properties as the graphene monolayers. The net spin of the functionalized zigzag GNRs was mainly localized on the edges demonstrating an adsorption site-dependent magnetism. For the zigzag GNRs, both the M2 (AA) and M2 (AB) configurations possibly had a magnetic moment. Each aryl group could induce 1.5-3.5 μB into the molecule-graphene system. There was a metal-to-insulator transition after adsorption of the aryl groups for the zigzag GNRs.