Submicrosecond surface-induced dissociation of peptide ions in a MALDI TOF MS

Surface-induced dissociation (SID) has been implemented in a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI TOF MS), allowing production of tandem mass spectrometric information for peptide ions (MALDI TOF SID TOF). The instrument retains the standard operational modes such as the reflectron monitoring of the MALDI-generated intact ions and postsource decay. We show through ion trajectory simulations and experimental results that implementing SID in a commercial MALDI TOF spectrometer is feasible and that the SID products in this instrument fall in an observation time frame that allows the specific detection of fast-fragmentation channels. The instrument design, pulse timing sequence, and high-voltage electronics together with SID spectra of MALDI-generated peptide ions are presented. Standard peptides such as YGGFLR, angiotensin III, fibrinopeptide A, and des-Arg1-bradykinin were dissociated by means of hyperthermal collisions with a gold surface coated with a self-assembled monolayer of 2-(perfluorodecyl)ethanethiol. With the extraction fields and the short observation times used, the spectra obtained show intense low-mass ion signals such as immonium, b2, b3, and y2 ions. TOF data analysis involved matching simulated and experimental flight times and indicates that the observed fragments are produced at approximately 250 ns after the precursor ion collides with the surface. This submicrosecond gas-phase fragmentation time frame is complementary to the observation time frame of existing SID spectrometers, which are on the order of 10 micros for tandem quadrupoles and are larger than a few milliseconds for SID implemented in Fourier transform ion cyclotron resonance spectrometers.     

Pilot-scale evaluation of ozone and biological activated carbon for trace organic contaminant mitigation and disinfection

In an effort to validate the use of ozone for contaminant oxidation and disinfection in water reclamation, extensive pilot testing was performed with ozone/H₂O₂ and biological activated carbon (BAC) at the Reno-Stead Water Reclamation Facility in Reno, Nevada. Three sets of samples were collected over a five-month period of continuous operation, and these samples were analyzed for a suite of trace organic contaminants (TOrCs), total estrogenicity, and several microbial surrogates, including the bacteriophage MS2, total and fecal coliforms, and Bacillus spores. Based on the high degree of microbial inactivation and contaminant destruction, this treatment train appears to be a viable alternative to the standard indirect potable reuse (IPR) configuration (i.e., membrane filtration, reverse osmosis, UV/H₂O₂, and aquifer injection), particularly for inland applications where brine disposal is an issue. Several issues, including regrowth of coliform bacteria in the BAC process, must be addressed prior to full-scale implementation.     

Extraction of rules from natural objects for automated mechanicalprocessing

In process applications, fast and accurate extraction of complex information from an object for the purpose of mechanical processing of that object, is often required. In this paper, a general rule-based approach is developed using a database of measurable geometric “features” and associated complex information. The rules relate the features to the complex processing information. During the on-line processing, the object features are measured and passed into the rule base. The output from the rule base is the complex information that is needed to process the object. A methodology is developed to generate probabilistic rules for the rule base using multivariate probability densities. A knowledge integration scheme is also developed which combines statistical knowledge with expert knowledge in order to improve the reliability and efficiency of information extraction. The rule generation methodology is implemented in a knowledge-based vision system for process information recognition. As an illustrative example, the problem of efficient head removal in an automated salmon processing plant is considered     

Luminomagnetic Nd3+ doped fluorapatite coated Fe3O4 nanostructures for biomedical applications

Luminomagnetic nanostructured Nd³⁺ doped fluorapatite (FAP) coated Fe₃O₄ nanoparticles were produced by hydrothermal method. X-ray diffraction analysis indicates that the prepared nanoparticles contain both FAP and Fe₃O₄ phases. Electron microscope analysis shows the formation of nanoparticles of Fe₃O₄ encased in rod shaped FAP nanoparticles of average length 40 nm. Magnetic measurements confirm the room temperature superparamagnetic nature of the nanoparticles with saturation magnetization value up to 7.8 emu/g. The prepared nanoparticles display strong near infrared (NIR) emission at 1060 nm under 800 nm excitation. Cell viability studies for 72 hour demonstrate the survival rate of over 84% with 500 μg/mL concentration indicating the good cytocompatibility of the prepared materials. The present Nd³⁺ doped FAP coated Fe₃O₄ nanostructure provides an excellent multifunctional platform for diagnostics and therapeutic applications.     

A real-time vision system for defect inspection in cast extrusion manufacturing process

The cast extrusion manufacturing process is the initial step which enables the creation of the raw materials, such as clear polypropylene film, needed for the flexible packaging printing process. The current methodology of controlling extrusion-related defect occurrences is attempted by a combination of statistical sampling and human inspection. However, due to the fact that the defects are small in size and hard to visualise in a clear thin film 2 m in width moving at a speed of 50 m/min. This results in poor product quality and high return ratio from customers. To the best of our knowledge, there is no system available that can accurately detect such defects. This research investigates possible defect detection methodologies and has subsequently proposed a system that is capable of real-time monitoring of defects on the cast extrusion manufacturing process. The proposed system utilises the refraction of a collimated light source, which is referred to as Mie light scattering. A vision analysis system is subsequently used to perform a blob analysis to detect the contrasting dark regions of the defects. Two test rigs were constructed to test the feasibility of the system. The first test rig was created to test the theoretical Mie scattering principles and the performance of the image analysis software in practice. The second test rig was created to test the practicability of integrating the Mie scattering theory on the physical cast extrusion line. The results obtained from the tests indicated a success rate of 90% in identifying gels and a 100% success rate in correctly identifying all the die lines presented in the tested samples. It is also deduced that the software has a capability to detect gel granules with a diameter greater than 480 μm and die lines with a thickness greater than 320 μm amid complete repeatability, ensuring that the proposed system fully conforms to the standard industrial requirements.     

A new route to control texture of materials: Nanostructured ZnFe2O4 photoelectrodes

Studies were conducted to investigate the influence of deposition solution composition (methanol ≤ the deposition solvent ≤ ethanol) on their physical and chemical properties that matters in the aerosol formation and subsequent decomposition during the aerosol assisted chemical vapour deposition (AACVD) of ZnFe₂O₄ electrodes. The FEGSEM studies found that the change of composition of deposition solution produced a dramatic change in the ZnFe₂O₄ electrode texture. The ZnFe₂O₄ electrodes deposited from methanol as well as predominately methanolic solvents had a relatively compact morphology. In contrast, the electrodes deposited from ethanol as well as predominately ethanolic solvents showed highly textured rod-like structure at nanoscale. The change in electrode texture is explained in terms of changes occurred in precursor decomposition pathways from heterogeneous and homogeneous when the composition of deposition solution is systematically varied. The photoelectrochemical (PEC) properties of all ZnFe₂O₄ electrodes were studied by recording J–V characteristics under AM1.5 illumination and the photocurrent spectra. The textured electrodes exhibited a significantly higher photocurrent compared to their compact counterparts. This is attributed to the improved photogenerated minority carrier collection at the ZnFe₂O₄/electrolyte interface as the average feature size gradually decreased. The photocurrent density (at 0.25 V vs. Ag/AgCl/3M KCl) increases rapidly when the electrode is deposited from the solvent containing 60% ethanol and above, which is in close agreement with the textural changes taken place in ZnFe₂O₄ electrodes.     

In vitro accessibility of β‐carotene from cooked Sri Lankan green leafy vegetables and their estimated contribution to vitamin A requirement

Vitamin A deficiency is an important issue for public health in Sri Lanka, where pro‐vitamin A carotenoids from green leafy vegetables provide most of the dietary vitamin A. The objective of this study was to analyse the β‐carotene content of seven types of green leafy vegetables and calculate the contribution of one traditionally cooked portion to the recommended daily allowance (RDA) of retinol. The total amount and in vitro accessibility of β‐carotene were determined using HPLC. The in vitro method simulates the conditions in the human intestinal tract. The all‐trans‐β‐carotene content in the fresh blanched vegetables ranged from 149 µg g^?1 dry weight (DW) in leaves of Alternanthera sessilis (mukunuwanna) to 565 µg g^?1 DW in Amaranthus caudatus (thampala). One portion (100 g) of green leaves cooked without fat (coconut) only contributed from 140 to 180 µg mg^?1 of the recommended daily allowance. A. sessilis, Centella asiatica (gotukola), Spinacea oleracea (nivithi) and A. caudatus, cooked with coconut fat contributed 140–680 µg mg^?1. However, stir‐fried or ‘malluma’ preparations (with coconut products) of Sesbania grandiflora (kathurumurunga) and Manihot esculenta (manioc) may provide more than 1.59–4.37 times the RDA of retinol. These results show that not only the choice of green leaves used but also the addition of fat while cooking is of great importance. Copyright © 2005 Society of Chemical Industry     

A study of the effects of postcure treatments on polyester–melamine coating matrices

The effect of postcure high energy (γ), ultraviolet (UV) and thermal treatment on the properties of polyester–melamine clearcoats of a range of compositions has been investigated. Two initial cure conditions were used, of which one was “optimally” cured and the other under‐cured. It was found that postcure treatments, particularly γ and UV, led to coatings of similar mechanical and thermal properties irrespective of initial cure, although the change in properties on postcure treatment was greater for the under‐cured samples. The results were interpreted in terms of the effect of the treatments on the structure of the crosslinked matrices. The study suggests the possibility of the development of a dual‐cure process for polyester–melamines, whereby cure optimization and property improvement can be achieved. This could also be used to “correct” for small variations in thermal cure levels brought about by adventitious on‐line fluctuations in cure oven conditions. POLYM. ENG. SCI. 46:532–539, 2006. © 2006 Society of Plastics Engineers