Cationic liposomes in mixed didodecyldimethylammonium bromide and dioctadecyldimethylammonium bromide aqueous dispersions studied by differential scanning calorimetry, Nile Red fluorescence, and turbidity

The thermotropic phase behavior of cationic liposomes in mixtures of two of the most investigated liposome-forming double-chain lipids, dioctadecyldimethylammonium bromide (DODAB) and didodecyldimethylammonium bromide (DDAB), was investigated by differential scanning calorimetry (DSC), turbidity, and Nile Red fluorescence. The dispersions were investigated at 1.0 mM total surfactant concentration and varying DODAB and DDAB concentrations. The gel to liquid-crystalline phase transition temperatures (Tm) of neat DDAB and DODAB in aqueous dispersions are around 16 and 43 degrees C, respectively, and we aim to investigate the Tm behavior for mixtures of these cationic lipids. Overall, DDAB reduces the Tm of DODAB, the transition temperature depending on the DDAB content, but the Tm of DDAB is roughly independent of the DODAB concentration. Both DSC and fluorescence measurements show that, within the mixture, at room temperature (ca. 22 degrees C), the DDAB-rich liposomes are in the liquid-crystalline state, whereas the DODAB-rich liposomes are in the gel state. DSC results point to a higher affinity of DDAB for DODAB liposomes than the reverse, resulting in two populations of mixed DDAB/DODAB liposomes with distinctive phase behavior. Fluorescence measurements also show that the presence of a small amount of DODAB in DDAB-rich liposomes causes a pronounced effect in Nile Red emission, due to the increase in liposome size, as inferred from turbidity results.     

Behavioral measures of frequency selectivity in the chinchilla.

A simultaneous masking procedure was used to derive four measures of frequency selectivity in the chinchilla. The first experiment measured critical masking ratios (CRs) at various signal frequencies. Estimates of the chinchillas' critical bandwidths derived from the CRs were much broader than comparable human estimates, indicating that the chinchilla may have inferior frequency selectivity. The second experiment measured critical bandwidths at 1, 2, and 4 kHz in a band-narrowing experiment. This technique yielded narrower estimates of critical bandwidth; however, chinchillas continued to exhibit poor frequency selectivity compared to man. The third experiment measured auditory-filter shape at 0.5, 1, and 2 kHz via rippled noise masking. Results of the rippled noise masking experiment indicate that auditory filters of humans and chinchillas are similar in terms of shape and bandwidth with chinchillas showing only slightly poorer frequency selectivity. The final experiment measured auditory filter shape at 0.5, 1, 2, and 4 kHz using notched noise masking. This experiment yielded auditory filter shapes and bandwidths similar to those derived from man. The discrepancy between the indirect estimates of frequency selectivity derived from CR and band-narrowing techniques and the direct estimates derived from rippled noise and notched noise masking are explained by taking into account the processing efficiency of the subjects.     

Optimal allocation of drug control efforts: A differential game analysis

The present paper considers a dynamic nonzero-sum game between drug dealers and the authorities. Although the game is neither linear-quadratic nor degenerate, in the sense that the closed-loop equilibria coincide with the open-loop equilibria, we are able to calculate explicitly a stationary feedback Nash equilibrium of that game. In a numerical example, we determine the optimal allocation of governmental efforts between treatment and law enforcement minimizing the total discounted cost stream in the equilibrium. Moreover, we provide sensitivity analyses with respect to the efficiency parameters of both competitors. Our results show that a farsighted authority should attack the drug problem from the demand side and put much effort in treatment measures and the improvement of the efficiency of the treatment.This research was supported by the Austrian Science Foundation under Contract P9112-SOZ. We would like to thank A. Luhmer and E. J. Dockner for helpful comments.     

Über den oxydativen Abbau vonmyo-Inosit durch einige Sproßpilzarten

Zusammenfassung Unter 36 untersuchten Sproßpilzarten erwiesen sich drei, nämlichSchwanniomyces occidentalis, Cryptococcus neoformans undCandida krusei, dazu befähigt, auf einem Nährboden, dermyo-Inosit als einzige Kohlenstoffquelle enthält, zu wachsen und auch Inost oxydativ abzubauen.Die Untersuchung anSchwanniomyces occidentalis ergab, daß das für die Oxydation vonmyo-Inosit verantwortliche Enzymsystem nicht konstitutiv ist, sondern durch Inosit induziert wird. Beim oxydativen Abbau von Inosit werden pro Mol Inosit drei Mole Sauerstoff aufgenommen bzw. drei Mole Kohlendioxyd gebildet.Mit 2 Abbildungen     

Relative reactivities of carbonyl and thiocarbonyl groups toward dimethoxycarbene: two new dimethoxythiiranes

Reaction of dimethoxycarbene (DMC), generated by thermolysis of a 2,5-dihydro-1,3,4-oxadiazole, with 2,2,4,4-tetramethyl-3-thioxocyclobutanone afforded primarily 2,2-dimethoxy-3,3,5,5-tetramethyl-4-thioxocyclopentanone from ring expansion by overall insertion into the C-CO bond. 4,4-Dimethoxy-2,2,5,5-tetramethyl-3-thioxocyclopentanone, from overall insertion into a C-CS bond, was a minor product. Thus the carbene had reacted preferentially at the carbonyl group, rather than the thiocarbonyl group of the four-membered ring. However, the minor product reacted with DMC at the thiocarbonyl group to afford a dimethoxythiirane. A product from a corresponding reaction at the carbonyl group could not be found. A rationale for the apparent reversal of relative reactivities of the carbonyl and thiocarbonyl groups is offered, with supporting evidence.     

The first 2,2-dialkoxythiirane

[reaction: see text] Thermolysis of 1 at 110 degrees C in benzene containing adamantanethione leads to thiirane 2 in 92% yield, as an isolable, stable solid. Compound 2 is the first example of the hitherto unknown 2,2-dialkoxythiiranes. It shows some reactions characteristic of thiiranes.     

Multivariable Heuristic Approach to Intrusion Detection in Network Environments

The Internet is an inseparable part of our contemporary lives. This means that protection against threats and attacks is crucial for major companies and for individual users. There is a demand for the ongoing development of methods for ensuring security in cyberspace. A crucial cybersecurity solution is intrusion detection systems, which detect attacks in network environments and responds appropriately. This article presents a new multivariable heuristic intrusion detection algorithm based on different types of flags and values of entropy. The data is shared by organisations to help increase the effectiveness of intrusion detection. The authors also propose default values for parameters of a heuristic algorithm and values regarding detection thresholds. This solution has been implemented in a well-known, open-source system and verified with a series of tests. Additionally, the authors investigated how updating the variables affects the intrusion detection process. The results confirmed the effectiveness of the proposed approach and heuristic algorithm.     

Determination of heat transfer correlations for plate-fin-and-tube heat exchangers

This paper presents a numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined using a non-linear regression method. Correlation coefficients were determined from the condition that the sum of squared fluid temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The outlet temperature of the fluid leaving the heat exchanger was calculated using the mathematical model describing the heat transfer in the heat exchanger. Since the conditions at the liquid-side and those at the air-side are identified simultaneously, the derived correlations are valid in a wide range of flow rate changes of the air and liquid. This is especially important for partial loads of the exchanger, when the heat transfer rate is lower than the nominal load. The correlation for the average heat transfer coefficient on the air-side based on the experimental data was compared with the correlation obtained from numerical simulation of 3D fluid and heat flow, performed by means of the commercially available CFD code. The numerical predictions are in good agreement with the experimental data.     

Low-Molecular-Weight Secondary Metabolites from Fungi: Cerrena unicolor as a New Proposal of an Effective Preparation against Rhabditis Nematodes

Plants and fungi are known as a valuable source of natural medicines used in the treatment of various diseases. Many of them are used to treat human and animal gastrointestinal diseases caused by parasites. The aim of this study was to investigate for the first time the antinematode properties of extracellular low-molecular subfractions (ex-LMS) obtained from the liquid growth medium of idiophasic Cerrena unicolor cultures. The fungal fractions were isolated according to a procedure previously described by Jaszek et al. The in vitro tests were performed using nematodes of the Rhabditis genus. As demonstrated by the results, the total fraction with a molecular weight < 10 kDa (CU-A) and the 0.02–1.5 kDa fraction (CU-B) had nematicidal activity. It was found that the analyzed substances induced movement disturbances caused by the paralysis of the back part of the nematode’s body. The degree of body paralysis was proportional to the increase in the concentration of the tested fractions. Summarizing the obtained results in the context of the available literature data, it seems that C. unicolor may be a good new candidate for research on nematode infections.     

19F MRI Probes for Multimodal Imaging**

Magnetic resonance imaging (MRI) is one of the most powerful imaging tools today, capable of displaying superior soft-tissue contrast. This review discusses developments in the field of ¹⁹F MRI multimodal probes in combination with optical fluorescence imaging (OFI), ¹H MRI, chemical exchange saturation transfer (CEST) MRI, ultrasonography (USG), X-ray computed tomography (CT), single photon emission tomography (SPECT), positron emission tomography (PET), and photoacoustic imaging (PAI). In each case, multimodal ¹⁹F MRI probes compensate for the deficiency of individual techniques and offer improved sensitivity or accuracy of detection over unimodal counterparts. Strategies for designing ¹⁹F MRI multimodal probes are described with respect to their structure, physicochemical properties, biocompatibility, and the quality of images.