Phenothiazinium photosensitisers,Part VI: Photobactericidal asymmetric derivatives

The synthesis of derivatives of Methylene Blue (C.I. Basic Blue 9) has generally employed symmetrical and non-symmetrical dialkylamine functionality in the auxochromic C-3 and C-7 positions of the chromophore. In the present work asymmetric derivatives were synthesised having dialkylamino groups at position 3 and either arylamino or aralkylamino groups at position 7, of the phenothiazinium ring. Physicochemical testing of the derivatives showed that the λ_max and ?_max values of the asymmetrical derivatives having arylamine substitution were very close to those of the symmetrical bis(dialkylamino) analogues but that the singlet oxygen yields were minimal, in line with previously published work concerning symmetrical bis(arylamino) derivatives. Synthesised asymmetric analogues having benzylamino or cyclohexylamino, rather than arylamino-substitution exhibited restored singlet oxygen generation. As expected, in screening tests against Gram-positive and Gram-negative bacteria, the aralkylamino and cyclohexylamino derivatives were highly active on illumination, presumably via singlet oxygen damage. However, the asymmetric arylamino derivatives were similarly photobactericidal, possibly due to molecular rigidification of these derivatives in the cellular milieu. Considerably increased activity was observed in each class relative to that of the standard methylene blue. In addition, the more lipophilic derivatives exhibited greater activity against Escherichia coli. This may be due to increased interaction with the lipid-rich outer membrane of this Gram-negative organism.     

Modeling of continuous self‐classifying spiral jet mills part 1: Model structure and validation using mill experiments

The objective of this work is to develop a milling model for a continuous self‐classifying spiral air jet mill. Its foundation is a population balance model with selection and breakage distribution functions that have been related to a minimal number of mill‐dependent and powder‐dependent parameters. Initially, experimentation is required to determine the mill‐dependent parameters for a specific mill, by milling a “base” powder at multiple operating conditions. Powder‐dependent parameters can be determined from either mill experiments or from material characterization measurements that require small amounts of powder (presented in Part 2). Ultimately, the milling model presented successfully predicts the product particle size using as inputs the feed particle‐size distribution and mill operating conditions. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the proposed milling model. © 2014 American Institute of Chemical Engineers AIChE J 60: 4086–4095, 2014     

Quenched solid density functional theory method for characterization of mesoporous carbons by nitrogen adsorption

Quenched solid density functional theory (QSDFT) model for characterization of mesoporous carbons using nitrogen adsorption is extended to cylindrical and spherical pore geometries. The kernels of theoretical isotherms in the range from 0.4 to 50 nm are constructed accounting for different possible variations of the pore shapes in micropore and mesopore regions. The results of QSDFT method are illustrated with experimental data on adsorption on novel CMK-3 and 3DOm carbons. The proposed method is recommended for pore size distribution calculations for micro–mesoporous carbons obtained through various templating mechanisms.     

A homoserine lactone autoinducer regulates virulence of an insect-pathogenic bacterium, Xenorhabdus nematophilus (Enterobacteriaceae)

N-beta-Hydroxybutanoyl homoserine lactone (HBHL), the autoinducer of the luminescent system of Vibrio harveyi, has been identified as the first small compound to restore virulence to avirulent mutants of Xenorhabdus nematophilus. HBHL stimulated the level of lipase activity excreted by avirulent X. nematophilus and lowered the phenoloxidase activity in the hemolymph of insects infected with X. nematophilus, parameters that are both associated with insect pathogenesis. Moreover, mortality of the insects infected with avirulent X. nematophilus was restored upon injection with HBHL. Chloroform extraction of medium conditioned with wild-type but not avirulent X. nematophilus led to the isolation of a compound with the same chromatographic mobility as HBHL as well as the ability to stimulate the luminescence of a dim autoinducer-dependent mutant of V. harveyi. Transfer of the V. harveyi lux operon into avirulent and wild-type X. nematophilus generated dim and bright luminescent strains, respectively, which responded to HBHL and an agonist and antagonist in a manner analogous to their effects on the luminescence of dim autoinducer-deficient and bright wild-type strains of V. harveyi, indicating that similar HBHL-dependent regulatory systems exist in these two bacterial species.     

Efficient Flight Control via Mechanical Impedance Manipulation: Energy Analyses for Hummingbird-Inspired MAVs

Within the growing family of unmanned aerial vehicles (UAV), flapping-wing micro aerial vehicles (MAV) are a relatively new field of research. Inspired by small size and agile flight of insects and birds, these systems offer a great potential for applications such as reconnaissance, surveillance, search and rescue, mapping, etc. Nevertheless, practicality of these vehicles depends on how we address various challenges ranging from control methodology to morphological construction and power supply design. A reasonable approach to resolving such problems is to acquire further inspiration from solutions in nature. Through modeling synchronous muscles in insects, we have shown that manipulation of mechanical impedance properties at wing joints can be a very efficient method for controlling lift and thrust production in flapping-wing MAVs. In the present work, we describe how this approach can be used to decouple lift/thrust regulation, thus reducing the complexity of flight controller. Although of simple design, this controller is still capable of demonstrating a high degree of precision and maneuverability throughout various simulated flight experiments with different types of trajectories. Furthermore, we use these flight simulations to investigate the power requirements of our control approach. The results indicate that these characteristics are considerably lower compared to when conventional control strategies—methods that often rely on manipulating stroke properties such as frequency or magnitude of the flapping motion—are employed. With less power demands, we believe our proposed control strategy is able to significantly improve flight time in future flapping-wing MAVs.     

Modeling Synchronous Muscle Function in Insect Flight: a Bio-Inspired Approach to Force Control in Flapping-Wing MAVs

Micro-aerial vehicles (MAV) and their promising applications—such as undetected surveillance or exploration of environments with little space for land-based maneuvers—are a well-known topic in the field of aerial robotics. Inspired by high maneuverability and agile flight of insects, over the past two decades a significant amount of effort has been dedicated to research on flapping-wing MAVs, most of which aim to address unique challenges in morphological construction, force production, and control strategy. Although remarkable solutions have been found for sufficient lift generation, effective methods for motion control still remain an open problem. The focus of this paper is to investigate general flight control mechanisms that are potentially used by real insects, thereby providing inspirations for flapping-wing MAV control. Through modeling the insect flight muscles, we show that stiffness and set point of the wing’s joint can be respectively tuned to regulate the wing’s lift and thrust forces. Therefore, employing a suitable controller with variable impedance actuators at each wing joint is a prospective approach to agile flight control of insect-inspired MAVs. The results of simulated flight experiments with one such controller are provided and support our claim.     

Myt1: a membrane-associated inhibitory kinase that phosphorylates Cdc2 on both threonine-14 and tyrosine-15

Cdc2 is the cyclin-dependent kinase that controls entry of cells into mitosis. Phosphorylation of Cdc2 on threonine-14 and tyrosine-15 inhibits the activity of the enzyme and prevents premature initiation of mitosis. Although Wee1 has been identified as the kinase that phosphorylates tyrosine-15 in various organisms, the threonine-14-specific kinase has not been isolated. A complementary DNA was cloned from Xenopus that encodes Myt1, a member of the Wee1 family that was discovered to phosphorylate Cdc2 efficiently on both threonine-14 and tyrosine-15. Myt1 is a membrane-associated protein that contains a putative transmembrane segment. Immunodepletion studies suggested that Myt1 is the predominant threonine-14-specific kinase in Xenopus egg extracts. Myt1 activity is highly regulated during the cell cycle, suggesting that this relative of Wee1 plays a role in mitotic control.     

Thermoforming triangular troughs

This analysis for thermoforming triangular troughs focuses on the manufacturing process speed and follows the method of Kershner and Giacomin for thermoforming cones. We distinguish between what happens before and after (free versus constrained forming) the melt touches the prismatic mold. Neither free nor constrained forming yields analytical solutions for the required forming time. Our analysis is restricted to the fabrication of triangular troughs from nearly Newtonian melts, the second simplest relevant problem in commercial thermoforming. The simplest relevant problem, thermoforming cones, yielded analytical solutions for the forming time. Whenever we thermoform straight edges into rigid packaging, the problem of a melt stretching into a triangular trough arises. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Development of a confined water sensitive urban design (WSUD) system using engineered soils.

Innovative Water Sensitive Urban Design (WSUD) systems are being investigated at three locations to the north and south of Sydney, Australia. These systems contain porous concrete pipes that are designed so that stormwater exfiltrates through the permeable walls of the pipes into the surrounding substrate media material. The porous pipes and media material treat the passing stormwater. The primary aim of the overall project is to develop a model to describe the treatment effectiveness of confined WSUD systems. This paper focuses on the system located at the Weathertex Industrial Site, Heatherbrae. Due to wood processing operations that occur at this site, it is recognised that the surface runoff will carry a heavy organics loading. Granulated Activated Carbon (GAC) is recognised for its ability to reduce the concentration of dissolved organics present in both wastewater and stormwater. GAC was therefore chosen as a filtration medium to be investigated at this site. To maximise the effectiveness of the GAC, extensive laboratory batch studies were undertaken prior to the field system being constructed to determine the optimum GAC/sand ratio. The purpose of the experimental work was to assess the dissolved organic removal potential through sorption of various concentrations of GAC. The aim of this paper is to describe these laboratory experiments and discuss how they related to the field system. Through these experiments it was determined that a sand/GAC ratio of 25:1 was ideal for the media material at the Heatherbrae site.     

Rail passenger perceptions of risk and safety and priorities for improvement

Recommendation 60 of the Ladbroke Grove rail inquiry stated that “comprehensive market research in regard to safety related measures should be carried out in order to take account of the views of informed passengers” (Cullen 2001, p. 235). In response, the Rail Safety and Standards Board Limited (RSSB) commissioned a survey of railway passengers nationwide, to investigate passenger perceptions of risk and safety at stations, on platforms and on trains, and to research passenger preferences for implementing safety interventions. Following qualitative interviews conducted with rail travellers, two separate questionnaires were designed and piloted. Each survey was administered face-to-face at 15 hub railway stations nationwide, according to a quota sample, and respondents were asked to return completed questionnaires by post. The overall response rate was approximately one-third. The results of the safety and risk survey provide a valuable indicator of passenger perceptions of risk, especially when compared to quantitative assessments of actual risk. The findings suggest that the relationship between perceived and actual risk is not particularly strong. The data from the passenger preferences questionnaire were analysed using conjoint techniques, and the results provide information on passenger preferences and priorities for improvement. The results are likely to be of value to the railway industry in allowing passenger preferences to be taken into account when implementing safety interventions.