Camera self-calibration method suitable for variant camera constraints

This paper presents a self-calibration algorithm that seeks the camera intrinsic parameters to minimize the sum of squared distances between the measured and reprojected image points. By exploiting the constraints provided by the fundamental matrices, the function to be minimized can be directly reduced to a function of the camera intrinsic parameters; thus variant camera constraints such as fixed or varying focal lengths can be easily imposed by controlling the parameters of the resulting function. We employed the simplex method to minimize the resulting function and tested the proposed algorithm on some simulated and real data. The experimental results demonstrate that our algorithm performs well for variant camera constraints and for two-view and multiple-view cases.     

X-ray photoelectron spectroscopy study of thin TiO2 films cosputtered with Al

In this study, titanium dioxide (TiO(2)) films were fabricated by cosputtering of a titanium (Ti) target and an aluminum (Al) slice in a smaller area by an ion-beam sputtering deposition method. The sputtered films were postannealed at 450 degrees C. The x-ray photoelectron spectroscopy spectra were categorized by their oxygen bonding variations, which include high-binding-energy oxygen, (HBO), bridging oxygen, low-binding-energy oxygen, and shifts of the binding energies (BEs) of oxygen (O) and Ti signals. The enhancement of HBO and higher BE shifts of the O 1s spectra as a function of cosputtered Al in the film imply the formation of an Al-O-Ti linkage. Corresponding changes in the Ti 2p spectra further confirm the modification of properties of the cosputtered film that results from the variation of the chemical bonding environment. An observed correlation between the chemical structure and optical absorption of the Al cosputtered films can be used to modify the optical properties of the film.     

Fates of seeded Escherichia coli O157:H7 and Salmonella on selected fresh culinary herbs during refrigerated storage

The fates of seeded Escherichia coli O157:H7 and Salmonella on selected fresh culinary herbs were evaluated at a refrigerated temperature (4 degrees C). Fresh herbs, including cilantro, oregano, basil, chive, parsley, and rosemary, were inoculated with six-strain mixtures of E. coli O157:H7 and Salmonella, and the microbial populations were monitored at 1, 5, 11, 16, 19, and 24 days. For both pathogens, a significant decrease in the population (P < 0.0001) occurred within the first 5 days of storage (< 0.8 log). Both pathogens remained the highest on cilantro and the lowest on rosemary (P < 0.0001). Storage time had a significant effect on the survival of E. coli O157:H7; populations declined as storage time progressed. Although storage of cilantro, basil, and chive was terminated after 19 days because of deteriorated quality, significant numbers of both pathogens were recovered from the remaining fresh herbs after 24 days of storage. The results showed that both bacteria were extremely persistent on all test herbs under the test conditions. The results also reinforce the concept that, once contaminated, bacterial pathogens can persist on fresh herbs throughout a normal distribution time.     

Unusually strong positive cooperativity in binding of peptides to latent membrane protein-1 DNA fragments of the Epstein-Barr viral gene

The DNA-binding preferences of two oligopeptide amides, (His-Pro-Arg-Lys)(3)NH(2) (HR-12) and (Ser-Pro-Arg-Lys)(3)NH(2) (SP-12), have been examined by quantitative DNase I footprinting studies. Two different DNA fragments were investigated: a pair of 5'-(32)P-labeled duplexes from pBR322 with one or other of the complementary strands labeled and a corresponding pair of 5'-(32)P-labeled duplexes representing fragments of the latent membrane protein (LMP-1) gene from a pathogenic Epstein-Barr virus variant derived from nasopharyngeal carcinoma. The major objective was to examine molecular recognition and cooperative features associated with sequence-selective binding of synthetic peptides to the LMP-1 fragments. At various binding sites on the pBR322 fragments, Hill coefficients (n(H)) ranging from 1.9-2.2 were observed; these results indicate modest positive cooperativity between binding sites for both peptides. By contrast, unusually high values of n(H), ranging from 4.0-9.3, were observed at various binding sites on the LMP-1 fragments. Allosteric models can be constructed to interpret the observed cooperative interactions between different DNA recognition sites in the LMP-1 gene upon binding of the peptide ligands. It is noteworthy that these models feature a novel network of cooperativity interconnecting multiple DNA allosteric sites. The evidence of sequence selectivity and strong cooperativity discovered in this work may prove to be a general feature of peptide interactions with some nucleic acids.     

Enhanced stability of recombinant keratinocyte growth factor by mutagenesis

Native sequence keratinocyte growth factor (KGF) is fairly unstable, as manifested by the loss of the monomeric native protein accompanied by the accumulation of aggregated species during storage at moderate temperatures. Several different types of analogs were generated and the storage stability of the protein assessed. In the first type of analog one or more of the five cysteinyl residues in KGF were replaced; in the second class the N-terminal residues that included the first disulfide bond were deleted. Both of these types of analogs involved removal of the disulfide bond between cysteines 1 and 15. The third group involved mutating one of the basic amino acids located in a cluster of positive charges (involved in heparin binding) around Arg144 to a neutral or acidic amino acyl residue. Among the cysteine replacement analogs, the double mutation of Cys1 and 15 to Ser resulted in significantly increased stability without compromising the mitogenic activity, while Cys to Ser mutations at other positions were either destabilizing or had no effect. Deletion of the 15, 23 or 27 N-terminal amino acyl residues also increased the stability of the protein. The activity of the analogs was not affected by the deletion of 15 or 23 amino acids, but it was significantly decreased upon removal of the 27 N-terminal amino acyl residues. Much greater stability was achieved by mutation of the basic amino acids, especially Arg144, to Glu or Gln, but this increase in stability was accompanied by large decrease in activity. The analog with the 23 N-terminal amino acyl residues deleted represents one of the best compromises between increased stability and retention of activity.     

Synthesis of carbon nanofibres from a liquid solution containing both catalyst and polyethylene glycol

Carbon nanofibres (CNFs) exhibiting bamboo-like, hollow fibril morphology were prepared from a mixture of polyethylene glycol (PEG) and iron-based compounds such as Fe(2)(SO(4))(3)·nH(2)O, Fe(NO(3))·9H(2)O or FeO(OH) by a thermal process. These materials were well mixed in distilled water prior to thermal treatment in an air/nitrogen atmosphere. With increasing temperature, the mixture underwent solvent removal, dehydrogenation, thermal decomposition, carbonization and catalytic graphitization to form CNFs. Results show that CNFs can be formed with different PEG/catalyst ratios (100/1-1000/1 by weight) at 750?°C. The catalyst effect is discussed for the formation of bamboo-like CNFs. The diameter of the CNFs was about 30-50?nm while the length was a few micrometres.     

Preparation of non-precious metal catalysts for PEMFC cathode from pyrolyzed vitamin B12

In this study, the effect of non-precious metal catalysts in the form of pyrolyzed Vitamin B12 that is supported by carbon black on oxygen reduction reaction (ORR) is examined. Pyrolysis was carried out at temperatures of 300 °C (py-B12/C-300), 500 °C (py-B12/C-500), 700 °C (py-B12/C-700) and 900 °C (py-B12/C-900) in an N₂-atmosphere. The ring-rotating disk electrode technique revealed that the electron-transfer numbers of py-B12/C-300, py-B12/C-500, py-B12/C-700 and py-B12/C-900 are 3.02, 3.42, 3.90 and 3.57, respectively: py-B12/C-700 exhibits near four-electron transfer. The X-ray absorption spectra demonstrate that during the pyrolysis, as the Co oxidation state of py-B12-700 is changed from Co(III) to Co(II), the Co coordination number changes from 6 to 4, suggesting that the structure is a square-planar Co–N₄ chelate. However, the Co–N₄ chelate is decomposed as the pyrolysis temperature increases to 900 °C, resulting in a loss of ORR activity. The H₂–O₂ PEMFC that uses py-B12/C-700 provides excellent performance, substantially outperforming py-CoTMPP/C.     

Optimization of probe-laser focal offsets for single-particle tracking

In optical tweezers applications, tracking a trapped particle is essential for force measurement. One of the most popular techniques for single-particle tracking is achieved by analyzing the forward and backward light pattern, scattered by the target particle trapped by a trap laser beam, of an additional probe-laser beam with different wavelength whose focus is slightly apart from the trapping center. However, the optimized focal offset has never been discussed. In this paper, we investigate the tracking range and sensitivity as a function of the focal offset between the trapping and the probe-laser beams. As a result, the optimized focal offsets are a 3.3-fold radius ahead and a 2.0-fold radius behind the trapping laser focus in the forward tracking and the backward tracking, respectively. The experimental result agrees well with a theoretical prediction using the Mie scattering theory.