In this paper, the electronic structures of NbO2 and Nb2O5 are theoretically and experimentally analyzed. The oxides in the samples are mainly consisted of NbO2 and NbO, whereas the outmost layer of the samples is NbO2. After exposure to air, the outermost layer on all niobium samples is Nb2O5. The photoelectrons from the first 2–4 Å contribute to the spectra, so the valence band structure of NbO2 and Nb2O5 can be confirmed from ultraviolet photoelectron spectroscopy (UPS). By comparing the UPS with density of state results, the electronic structure of NbO2 and Nb2O5 can be distinguished from each other, and then the electronic structure was deconvoluted into several electronic states. The agreement between experimental result and theory is, in the best case, satisfactory. Copyright © 2013 John Wiley & Sons, Ltd.

SUMMARYIn previous research, it was found that melamine-formaldehyde resin can be used as a binder for a hydroxy-functional organophosphorus flame retarding agent (FR) on cotton. The role that trimethylol melamine (TMM) plays in this flame retarding system was studied. When TMM is applied to cotton, it forms crosslinks between cellulose molecules. When TMM is applied to cotton in the presence of FR, it reacts with FR to form a crosslinked polymeric network in addition to reacting with cotton. The formation of the crosslinked network improves the laundering durability of FR and also increases the fabric stiffness. The number of crosslinks among cotton cellulose formed by TMM decreases as the FR concentration in the system is increased. TMM also functions as a nitrogen provider to enhance the flame retarding performance of FR due to phosphorus-nitrogen synergism. Therefore, the amount of TMM used in a FR/ TMM formula plays the most critical role in determining the effectiveness of this flame retarding system. The finish bath pH also plays a significant role in influencing the performance of the flame retarding system on cotton. The optimum pH was found to be around 4.

Ultrabroadband photodetection has been a hot topic with the rapid development of materials science and the application requirements for communication, imaging, and sensing. Photodetectors based on bandgap-independent bolometry are promising candidates for detection of light from the ultraviolet to the terahertz range. Here we report a photothermoelectric detector made of an alloy of EuBiSe3 single crystal. The device shows room-temperature self-powered photoresponse from ultraviolet (375 nm) to terahertz (163 μm) with nearly uniform sensitivity against wavelength and fast response speed. Thanks to the large thermoelectric power (Seebeck coefficient) of EuBiSe3, the photovoltage responsivity derived from the incident (not absorbed) power reaches as high as 1.69 V/W at 405 nm without any bias voltage and exceeds 0.59 V/W even at terahertz frequencies, with noise-equivalent power below 1 nW/ , which is 1–2 orders of magnitude lower than reported photothermoelectric detectors. The response time is around 200 ms, nearly 2 orders of magnitude faster than silicon-based heterojunction ultrabroadband photodetectors and on the same order as the millimetric-scale graphene- and carbon nanotube-based bolometric photodetectors. In addition, the as-grown EuBiSe3 crystal possesses a unique needle-like shape, intrinsically facilitating integration of the detector. Our work demonstrates that improved thermoelectric materials hold great promise for room-temperature, high-performance, broadband photodetection.

It is necessary to use a crosslinking agent to bond a flameretarding hydroxy-functional organophosphorus oligomer (FR) to cotton so that the flame resistance of the treated cotton fabric can be durable to multiple homelaundering. Both dimethyloldihydroxyethyleneurea (DMDHEU) and melamine– formaldehyde (M-F) have been used as the binding agents between FR and cotton. The vertical flammability, limiting oxygen index (LOI) and phosphorus content after different numbers of laundering cycles as well as the wrinkle resistance and tensile strength of the cotton fabric treated with FR/DMDHEU and FR/M-F was investigated and compared in this research. We found that DMDHEU is more effective for crosslinking cotton cellulose and for crosslinking between FR and cotton than M-F. We also found that the bonding formed by DMDHEU between cotton and FR is more durable to multiple laundering cycles than that formed by M-F. M-F is a more effective nitrogen provider than DMDHEU to enhance the flame retarding performance of the treated cotton fabric through phosphorus–nitrogen synergism, therefore the presence of M-F in the flame retardant finishing system significantly increases the flame resistance of the treated fabric. DMDHEU, as an effective crosslinking agent for cotton, causes more fabric strength loss than M-F.

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Ultra-broadband photodetection is crucial for various applications like imaging and sensing and has become a hot research topic in recent years. However, most of the reported ultra-broadband photodetectors can only cover the range from ultraviolet to infrared, which is insufficient. Herein, a photothermoelectric (PTE) detector made of NbS3 is reported. The device shows a considerable performance from ultraviolet to terahertz. For all examined wavelengths, the photoresponsivities are all larger than 1 V W–1 while the response time is less than 10 ms, much shorter than the reported ultra-broadband photodetectors made of millimetric scale graphene, ternary chalcogenide single crystal, and other materials. The extraordinary performance is fully discussed and can be attributed to the thermal localization enhanced PTE effect. Because of the short thermal decay length and low thermal loss, the heat generated by the illumination is localized in only a micrometer scale along the channel, and thus a strong PTE response is produced. In addition, the fabricated device also demonstrates robust flexibility and stability. Thanks to the quasi-one-dimensional (quasi-1D) structure, the NbS3 crystal is easy to be scaled down and thus intrinsically facilitate the integration of detectors. With these favorable merits, the quasi-1D NbS3 crystal holds a promising potential in high-performance, ultra-broadband photodetectors.

It is important to conduct error analysis of assemblies in order to ensure that the manufactured parts satisfy the design specifications. Traditionally, mechanical tolerances and clearances are modeled as random variables and the analysis is conducted using probabilistic methods. In this work, a new approach, based on interval analysis, is presented for the modeling and analysis of tolerances and clearances. The basic procedure of interval analysis involving solution of simultaneous nonlinear equations is described. The application of the approach in the fuzzy error analysis of planar and spatial mechanisms is also outlined. The treatment of the tolerances and clearances of the mechanism as interval numbers leads to a better and a more realistic estimation of the analysis results. Numerical examples are presented to illustrate the computational procedures. The results of the interval analysis, although philosophically different, are compared with those given by the probabilistic method for comparable input data; the differences found in the two sets of results are explained in terms of the basic characteristics of the two methods. This work denotes the first application of interval methods for the modeling of tolerances and clearances and the fuzzy error analysis of mechanisms.