Fröhlich's model of bose condensation in biological systems

Fröhlich's model of Bose-Einstein condensation in biological systems is analyzed using finite temperature Green's function techniques. The thermal average of the rate of change of vibrational mode quanta in the biological system is calculated and compared with Fröhlich's postulated rate equations. The appropriate phonon lifetime is also calculated and represents the minimum time needed to produce the condensed phase. The possible importance of this lifetime and its relation to recent microwave absorption experiments is discussed.     

Multifrequency Microwave Imaging for Brain Stroke Detection

CT and MRI are often used in the diagnosis and monitoring of stroke. However, they are expensive, time-consuming, produce ionizing radiation (CT), and not suitable for continuous monitoring stroke. Microwave imaging (MI) has been extensively investigated for identifying several types of human organs, including breast, brain, lung, liver, and gastric. The authors recently developed a holographic microwave imaging (HMI) algorithm for biological object detection. However, this method has difficulty in providing accurate information on embedded small inclusions. This paper describes the feasibility of the use of a multifrequency HMI algorithm for brain stroke detection. A numerical system, including HMI data collection model and a realistic head model, was developed to demonstrate the proposed method for imaging of brain tissues. Various experiments were carried out to evaluate the performance of the proposed method. Results of experiments carried out using multifrequency HMI have been compared with the results obtained from single frequency HMI. Results showed that multifrequency HMI could detect strokes and provide more accurate results of size and location than the single frequency HMI algorithm.     

利用微波-热效应进行限制性内切核酸酶反应的可行性验证

限制性内切酶催化的酶解反应是分子生物学实验中的常用技术.鉴于酶切反应时间长,有人提出采用微波释放的热效应催化限制性内切酶解反应,以期缩短酶解时间.但微波是否能代替传统酶切反应还需验证.本研究设计了一系列的酶切 试验,验证微波酶切是否有效.结果表明：短时间（2 min）微波炉高火处理未导致DNA降解及内切酶失活.对于质粒的单酶切和部分双酶切,短时间（2 min）微波炉处理可替代水浴加热完成酶解反应.对于部分双酶切体系,微波炉处理酶切不完全,不能替代温水浴.使用微波酶解需严格控制时间,切勿时间过长.     

Gravitational effects on biological systems

The possible effects of the earth's gravitational field on biological systems have been studied from a quantitative point of view, focusing the attention to a very simple system, a solution containing proteins, which biochemists might use in experiments. Gravity has been compared with other forces which are known to influence protein activity, including thermic agitation, weak electrostatic interactions, Van der Waals forces and viscous dissipation. Comparisons have been described in terms of the energy of the interaction per mole, referring to some physically simple cases and substances of biological interest. From this study it is evident that the earth's gravitational energy should be taken into account when considering the chemical behaviour of solutions containing substances that have high molecular weight, such as a typical protein, since its value is comparable to other weak interactions. Moreover, since solutions represent the basis of much more complex biological processes taking place inside cells, the influence of gravity should extend also to cellular biochemical behaviour, especially in presence of altered gravity, both in microgravity (such as on satellites orbiting around the earth), and in macrogravity (such as in a centrifugating biological system).     

Microwave imaging of tissue blood content changes

Active microwave imaging gives information on the dielectric properties of the body, allowing the collection of data that are distinct from, but complementary to, those available from other imaging methods based on different radiations. Two types of microwave imaging systems have been developed. The first is a planar system that irradiates the object with a plane wave and collects scattered phase and amplitude data at 1024 points on a parallel plane. The data can be reconstructed using a back propagation technique to give an image of the object. The second type of system is a tomographic scanner, consisting of a multiplexed 64-element circular array of waveguides. The waveguides are electronically scanned, alternately as sources and receivers, to give a complete scan of the object with no mechanical movement. A tomographic ‘slice’ of the object is reconstructed using spectral domain interpolation. Both systems work at 2.45 GHz with an incident power < 1 mW cm⁻² at the object and require a coupling medium (usually water) between the object and the source/receiver. Imaging parameters are appropriate for clinical use: a spatial resolution of 1 cm, measurement time of a few seconds and contrast resolution of around 1%. The effects of changes in perfusion on images of isolated animal organs are presented. Images have also been obtained, with both systems, of the internal dielectric structure of the forearm and of variations in dielectric properties due to changes of tissue blood content effected by application and release of tourniquets to the upper arm. Results s how that these changes are well demonstrated by microwave imaging, and possible clinical applications are discussed.     

Interaction between pancreatic β cell and electromagnetic fields: A systematic study toward finding the natural frequency spectrum of β cell system

Interaction between biological systems and environmental electric or magnetic fields has gained attention during the past few decades. Although there are a lot of studies that have been conducted for investigating such interaction, the reported results are considerably inconsistent. Besides the complexity of biological systems, the important reason for such inconsistent results may arise due to different excitation protocols that have been applied in different experiments. In order to investigate carefully the way that external electric or magnetic fields interact with a biological system, the parameters of excitation, such as intensity or frequency, should be selected purposefully due to the influence of these parameters on the system response. In this study, pancreatic β cell, the main player of blood glucose regulating system, is considered and the study is focused on finding the natural frequency spectrum of the system using modeling approach. Natural frequencies of a system are important characteristics of the system when external excitation is applied. The result of this study can help researchers to select proper frequency parameter for electrical excitation of β cell system. The results show that there are two distinct frequency ranges for natural frequency of β cell system, which consist of extremely low (or near zero) and 100–750 kHz frequency ranges. There are experimental works on β cell exposure to electromagnetic fields that support such finding.     

生物土壤结皮对准噶尔盆地5种荒漠植物幼苗生长与元素吸收的影响

生物土壤结皮广泛分布于许多干旱和半干旱地区, 它影响土壤物理过程、水文、侵蚀和养分循环过程, 从而影响植物种子萌发与生长发育。该文以新疆准噶尔盆地腹地的古尔班通古特沙漠的生物土壤结皮为研究对象, 分析了生物土壤结皮对准噶尔盆地5种荒漠植物(白梭梭(Haloxylon persicum)、蛇麻黄(Ephedra distachya)、角果藜(Ceratocarpus arenaarius)、涩芥(Malcolmia africana)和狭果鹤虱(Lappula semiglabra))的生长及其对元素吸收的影响。结果表明: 1)相对于裸沙而言, 生物土壤结皮显著促进了荒漠植物的生长速率, 并增加了草本植物地上和地下的生物量, 但对灌木的生物量无显著影响; 2)生物土壤结皮使部分一年生草本植物的开花和结实期提前, 这可能有利于荒漠植物在有限的环境资源下快速完成生活史, 并繁衍后代; 3)生物土壤结皮能够影响荒漠植物对土壤中营养元素的吸收, 具体表现在生物土壤结皮显著促进了5种植物对N的吸收, 增加了荒漠植物在N贫乏的荒漠生态系统的适应能力, 而对P和K的吸收均没有影响。生物土壤结皮对荒漠植物对元素吸收的影响因种而异, 对不同的植物有不同的影响。荒漠植物对Mg、Mn和Cu的吸收受生物土壤结皮的影响最小。     

Tuning,coupling and matching of a resonant cavity in microwave exposure system for biological objects

A new microwave exposure system for biological experiments with well-defined exposure conditions and improved control of the exposure parameters consisting of variable frequency power source, coaxial to waveguide transition, matching network and single-mode resonant cavity with movable shorting plunger was fabricated and characterized. The introduction of a biological sample into a resonant cavity has a large impact on its field configuration and port impedance. As such, the properties, geometry and position of the biological sample become a part of the electrical properties of the microwave circuit. With that change, the electrical properties of the resonant cavity, such as impedance, quality factor and resonant frequency, also change. In this study, an appropriate coupling system with effective power transfer and an algorithm to tuning and coupling of resonant cavity in resonance before and after the introduction of biological sample have been proposed. This procedure will lead to a known dose distribution within the biological sample and allow a better comparison with other studies. Coupling of the electromagnetic energy into a resonant cavity was experimentally investigated. Graphical representation of cavity impedance in case of undercoupled, critically coupled and overcoupled cavity has been presented. Critical coupling of an empty resonant cavity has been accomplished at voltage standing wave ratio (VSWR) 1.01, at resonance frequencies 900 and 947.5 MHz. Critical coupling with the introduction of a biological sample has been accomplished at VSWR ≤ 1.07 for frequency bandwidth 1 MHz and VSWR ≤ 1.5 for frequency bandwidth up to 5 MHz with central frequency 947.5 MHz.     

Controlled Microwave Processing Applied to the Pharmaceutical Formulation of Ibuprofen

The first successful development of controlled microwave processing for pharmaceutical formulations is presented and illustrated with a model drug (ibuprofen) and two excipients (stearic acid and polyvinylpyrrolidone). The necessary fine temperature control for formulation with microwave energy has been achieved using a uniquely modified microwave oven with direct temperature measurement and pulse-width modulation power control. In addition to comparing microwave and conventional heating, the effect of the presence of liquid (water) in aiding the mixing of the drug and excipient during formulation was also investigated. Analysis of the prepared formulations using differential scanning calorimetry and dissolution studies suggest that microwave and conventional heating produce similar products when applied to mixtures of ibuprofen and stearic acid. However, the differences were observed for the ibuprofen and polyvinylpyrrolidone formulation in terms of the dissolution kinetics. In all cases, the presence of water did not appear to influence the formulation to any appreciable degree. The application of controllable microwave heating is noteworthy as fine temperature control opens up opportunities for thermally sensitive materials for which microwave methods have not been feasible prior to this work.     

Biological invasions of Southern Ocean islands: the Collembola of Marion Island as a test of generalities

It has been suggested previously that the presence and abundance of indigenous species have a marked influence on the likelihood of invasion of a community. It has also been suggested that such biotic resistance has a negligible influence on the outcome of an invasion, but that the abiotic characteristics of the environment being invaded are more important. The latter has been claimed to be especially important on the islands of the Southern Ocean. In order to test these competing hypotheses we examined the distribution and abundance of indigenous and introduced springtails across 13 habitats, which differ considerably in the properties of their soils, and soil temperature, on the eastern quarter of sub‐Antarctic Marion Island. There was no evidence of negative abundance covariation or species associations within habitats, nor were there significant relationships between species richness or abundance of the indigenous as opposed to the introduced collembolans across habitats. Interspecific interactions thus seem to have played no readily identifiable role in the outcome of invasions by Collembola on Marion island. In contrast, the indigenous and introduced species responded very differently to abiotic variables. The indigenous Collembola prefer drier, more mineral soils with a low organic carbon content, and species richness tends to be highest in cold, fellfield areas. On the other hand, the introduced springtails prefer moist, warm sites, with organically enriched soils, introduced species richness was negligible in cold, fellfield areas. Disturbance also appeared to influence positively the species richness and abundance of introduced species at a site. These results provide independent support for the idea that abiotic factors, especially temperature, significantly influence the likelihood of biological invasions on Southern Ocean islands. They also suggest that predicting the outcome of climate change on community structure in this region is likely to be problematic, especially in the case of the Collembola.     

Extracellular calcium and microwave enhancement of membrane conductance in snail neurons

Summary Microwave irradiation has been shown to decrease the input resistance of snail neurons. In this study, we examined the role of extracellular calcium in triggering the microwave-induced enhancement of membrane conductance. Two sets of experiments were conducted. In the first set, nerve cells were superfused using Ringer solution with added Cd²⁺ (0.9 mM) which is a known blocker of calcium channels. In the second set, cells were superfused with low Ca²⁺ (0.7 mM) Ringer solution. Microwave irradiation was conducted at 2,450 MHz for 30 min with a specific absorption rate of 13 mW/g. It was found that 7 mM to 0.7 mM lowering of Ca²⁺ in bathing solution as well as blocking of calcium channels in neuronal membrane by means of Cd²⁺ did not influence the fall in membrane resistance induced by microwave radiation. In fact, the observed changed in membrane resistance in these experiments were nearly equal to those observed for neurons superfused by normal Ringer's. Thus, these results rule out the possible contribution of external Ca²⁺ in the observed microwave effect. Experiments with high Ca²⁺ solution also support this conclusion.     

Procedure for Evaluating the Effects of 2,450- Megahertz Microwaves upon Streptococcus faecalis and Saccharomyces cerevisiae

Modifications of a commercial 2,450-megahertz microwave oven were made so that 6 ml of microbial suspension could be exposed to the microwave field for various periods of time. The microorganisms were contained in the central tube of a modified Liebig condenser positioned in the approximate geometric center of the oven cavity. Kerosene at -25 C was circulated through the jacket of the condenser during microwave exposure permitting microwaves to reach the microbial suspension. Flow rates of the kerosene were varied to permit the temperature of the suspension to range from 25 to 55 C during microwave exposure. Conductive heating experiments using similar temperatures were also conducted. A thermocouple-relay system was employed to measure the suspension temperature immediately after the magnetron shutoff. Continuous application of microwaves to suspensions of 10(8) to 10(9)Streptococcus faecalis or Saccharomyces cerevisiae per ml appeared to produce no lethal effects other than those produced by heat. Respiration rates of microwave-exposed Scerevisiae were directly related to decreases in viable count produced by increased microwave exposure times.     

Light-Sheet Confined Super-Resolution Using Two-Photon Photoactivation

Light-sheet microscopy is a useful tool for performing biological investigations of thick samples and it has recently been demonstrated that it can also act as a suitable architecture for super-resolution imaging of thick biological samples by means of individual molecule localization. However, imaging in depth is still limited since it suffers from a reduction in image quality caused by scattering effects. This paper sets out to investigate the advantages of non-linear photoactivation implemented in a selective plane illumination configuration when imaging scattering samples. In particular, two-photon excitation is proven to improve imaging capabilities in terms of imaging depth and is expected to reduce light-sample interactions and sample photo-damage. Here, two-photon photoactivation is coupled to individual molecule localization methods based on light-sheet illumination (IML-SPIM), allowing super-resolution imaging of nuclear pH2AX in NB4 cells.     

The influence of the energy absorbed from microwave pretreatment on biogas production from secondary wastewater sludge

In this study, microwave treatment is analyzed as a way to accelerate the hydrolysis in anaerobic digestion of municipal wastewater sludge. The influence of the absorbed energy, power and athermal microwave effect on organic matter solubilization and biogas production has been studied. In addition, a novel method that considers the absorbed energy in the microwave system is proposed, in order to obtain comparable experimental results. The absorbed energy is calculated from an energy balance.The highest solubilization was achieved using 0.54 kJ/ml at 1000 W, where an increment of 7.1% was observed in methane production, compared to the untreated sample. Using a higher energy value (0.83 kJ/ml), methane production further increased (to 15.4%), but solubilization decreased. No power influence was found when 0.54 kJ/ml was applied at 1000, 600 and 440 W. Microwave heating was compared to conventional heating in two different experimental setups, providing similar methane yields in all cases.     

Computational analysis of the influence of the microenvironment on carcinogenesis

The tumour microenvironment is known to play an important role in determining the sequence of acquired phenotypic traits that characterise cancer evolution. A more precise understanding of this role could have a major influence in the understanding of cancer growth and development, and potentially in the optimisation of innovative anti-cancer treatments delivery. However, to lead such an analysis in the basis of traditional biological experiments and observations is almost utopian given the complexity of the underlying biological processes and the typical time scales involved. In this context, computer models constitute a complementary exploratory tool.In this paper we introduce a two-dimensional cellular automaton that models key cancer cell capabilities. The model has been especially designed to mimic the behaviour of a cancer colony growing in vitro and to analyse the effect of different environmental conditions on the sequence of acquisition of phenotypic traits. Our results indicate that microenvironmental factors such as the local concentration of oxygen or nutrients and cell overcrowding may determine the expansion of the tumour colony. The results also show that tumour cells evolve and that their phenotypes adapt to the microenvironment so that environmental stress determines the dominance of particular phenotypical traits.     

Relationship between alertness,performance, and body temperature in humans

Body temperature has been reported to influence human performance. Performance is reported to be better when body temperature is high/near its circadian peak and worse when body temperature is low/near its circadian minimum. We assessed whether this relationship between performance and body temperature reflects the regulation of both the internal biological timekeeping system and/or the influence of body temperature on performance independent of circadian phase. Fourteen subjects participated in a forced desynchrony protocol allowing assessment of the relationship between body temperature and performance while controlling for circadian phase and hours awake. Most neurobehavioral measures varied as a function of internal biological time and duration of wakefulness. A number of performance measures were better when body temperature was elevated, including working memory, subjective alertness, visual attention, and the slowest 10% of reaction times. These findings demonstrate that an increased body temperature, associated with and independent of internal biological time, is correlated with improved performance and alertness. These results support the hypothesis that body temperature modulates neurobehavioral function in humans.     

Interactions between learning and evolution: the outstanding strategy generated by the Baldwin effect

The Baldwin effect is known as an possible interaction between learning and evolution, where individual lifetime learning can influence the course of evolution without using any Lamarckian mechanism. Our concern is to consider the Baldwin effect in dynamic environments, especially when there is no explicit optimal solution through generations and this solution depends only on interactions among agents. We adopted the iterated Prisoner's Dilemma as a dynamic environment, introduced phenotypic plasticity into its strategies, and conducted computational experiments, in which phenotypic plasticity is allowed to evolve. The Baldwin effect was observed in the experiments as follows: First, strategies with enough plasticity spread, which caused a shift from defect-oriented populations to cooperative populations. Second, these strategies were replaced by a strategy with a modest amount of plasticity generated by interactions between learning and evolution. By making three kinds of analysis, we have shown that this strategy provides outstanding performance in comparison with other deterministic strategies. Further experiments towards open-ended evolution have also been conducted so as to generalize our results.     

Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving imaging system, such as an airborne platform or satellite. The resolution improvement is obtained in a two-step process. First, three low resolution differently defocused images are being captured and the optical phase is retrieved using an improved iterative Gerchberg-Saxton based algorithm. The phase retrieval allows to numerically back propagate the field to the aperture plane. Second, the imaging system is shifted and the first step is repeated. The obtained optical fields at the aperture plane are combined and a synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution. The method resembles a well-known approach from the microwave regime called the Synthetic Aperture Radar (SAR) in which the antenna size is synthetically increased along the platform propagation direction. The proposed method is demonstrated through laboratory experiment.     

Chlamydomonas: Fast tracking from genomics

Elucidating biological processes has relied on the establishment of model organisms, many of which offer advantageous features such as rapid axenic growth, extensive knowledge of their physiological features and gene content, and the ease with which they can be genetically manipulated. The unicellular green alga Chlamydomonas reinhardtii has been an exemplary model that has enabled many scientific breakthroughs over the decades, especially in the fields of photosynthesis, cilia function and biogenesis, and the acclimation of photosynthetic organisms to their environment. Here, we discuss recent molecular/technological advances that have been applied to C. reinhardtii and how they have further fostered its development as a “flagship” algal system. We also explore the future promise of this alga in leveraging advances in the fields of genomics, proteomics, imaging, and synthetic biology for addressing critical future biological issues.     

On the solution of the non-linear bio-heat equation

With reference to microwave localized hyperthermia, a non-linear model of the thermal behavior of living tissues, where local thermoregulating convective and conducting effects due to blood flow are taken into account, has been assumed. The non-linear operator equation for the space and time temperature distribution, which describes local energy balance (bio-heat equation), has been linearized and solved by using a variant of the Newton iterative method. Numerical calculations for plane stratified structures simulating living bodies, irradiated by plane electromagnetic waves, have been carried out.