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A ratiometric fluorescent chemosensor, Phos-1, was constructed with 4,5-diaminonaphthalimide as a fluorophore for selective and visual detection of phosgene. The sensing mechanism was demonstrated to be the phosgene molecule acylating both amine groups of Phos-1. A test paper with Phos-1 was fabricated for facile, selective and visual detection of phosgene gas.

Both collinear and noncollinear magnetic structures of FeMn with L1 0 atomic ordering were determined from total-energy full-potential linearized augmented plane-wave calculations incorporating noncollinear magnetism with no shape approximation for the magnetization density. Different spin-density orientations for the different band states are observed on a smaller length scale inside an atom. The presence of the intra-atomic noncollinear magnetism enhances the stability of the 3Q noncollinear magnetic structure, in which the magnetic moments align toward the center of the cell of four atoms, thus becoming the lowest-energy state of the structures considered.Antiferromagnetic ͑AFM͒ materials have attracted great attention in technological applications since the discovery of the exchange bias 1 associated with the interface between ferromagnetic ͑FM͒ and AFM materials. Among these, fcc FeMn is one of the useful candidates as an exchange bias AFM material. 2,3 Despite its importance, its magnetism is not well understood quantitatively since the experimental determinations of the magnetic properties are difficult due to the absence of a net magnetization in an AFM material.So far three models of magnetic structures in disordered FeMn have been proposed from experiments: 4 -7 a collinear AFM (1Q) structure and two noncollinear magnetic (2Q and 3Q) structures, as shown in Fig. 1. The magnetic Mn and Fe moments in the 1Q structure are in a collinear state while those in the 2Q structure align perpendicular to each other. For the 3Q structure, the magnetic moments align toward the center of the cell of four atoms, i.e., along different ͗111͘ directions. Originally, Kouvel and Kasper 4 first detected long-range AFM ordering by neutron-diffraction measurements, and found that either the 1Q or the 3Q structure could explain the data. Later, by means of Mössbauer and neutron diffraction, Endoh and Ishikawa 5 determined a magnetic phase diagram in a whole composition range of Fe x Mn 1Ϫx and expected the 3Q structure at the equiatomic composition. More recently, however, Kennedy and Hick 6 suggested the 2Q structure from Mössbauer transmission spectra and Bianti et al. 7 proposed the 1Q structure based on inelastic neutron experiments. Thus, the experiments still have an ambiguity in the determination of the magnetic ground state.From the theoretical point of view, using first-principles total-energy calculations Kübler et al. 8 and several other researchers 9,10 reported that the 2Q structure is energetically more stable than the other two structures when restricted to an L1 0 ordered state. Furthermore, their calculations were based on the atomic sphere approximation for the magnetization density, i.e., they assumed only one local spinquantization axis in each atomic sphere and the corresponding magnetization density was spherically averaged. Although these calculations have revealed the physical nature of the magnetism of FeMn, their energy differences are quite small and so quantitative highly precise predictions are nec...

To achieve an electronic level understanding of intergranular embrittlement and its control in steel, the first principles full potential linearized augmented plane wave method and the atomic force approach are used to investigate the effect of Mn additions and P impurities on the energetics and underlying electronic properties of both the Fe grain boundary ͑GB͒ and the corresponding intergranular fracture surface ͑FS͒. The calculated binding-energy difference is ϩ0.17 eV/adatom for P in the P/Fe binary system, in agreement with its observed embrittlement potency. The Mn is also found to contribute a direct embrittling effect of ϩ0.20 eV/adatom, associated with stronger Mn-Fe chemical bonding in the FS environment. The computed binding-energy difference for P in the ͑PϩMn͒/Fe ternary system is increased to ϩ0.40 eV/adatom, consistent with experimental evidence that Mn facilitates P embrittlement in the grain boundary. The origin of the Mn enhanced P embrittlement is attributed to the strengthened in-plane P-Mn interaction, which makes the P impurity interact more isotropically with the surrounding Mn and Fe atoms in the GB and FS.

An optical probe based on colorimetric and ratiometric as well as chemiluminometric signal outputs is developed for the specific detection of hydrazine. On the basis of a Gabriel-type reaction, hydrazinolysis of a simple probe CF (4-phtalamide-N-(4'-methylcoumarin) naphthalimide) produces both the fluorescence of 7-amino-4-methylcoumarin with the max emission wavelength changed from 480 to 420 nm (along with a color change from yellow to transparent) and the luminol chemiluminescence activated by H2O2 with a max emission wavelength at 450 nm. The experimental detection limit of hydrazine is 3.2 ppb (0.1 μM). Selectivity experiments proved CF has excellent selectivity to hydrazine over other interfering substances. Probe CF was also successfully applied in the vapor hydrazine detection over other interfering volatile analytes. Furthermore, the probe CF loaded thin-layer chromatography (TLC) plate for vapor hydrazine detection limit is 5.4 mg/m(3) which is well below the half lethal dose of hydrazine gas for mice (LC50(mice), 330 mg/m(3)) and National Institute of Occupational Safety and Health's immediately dangerous to life or health limit (NIOSHIDLH, 66 mg/m(3)). With H2O2, only hydrazinolysis product luminol can be lighted at 450 nm, other species have no signal. Probe CF can also be used for the detection of hydrazine in HeLa cells.