Electron Micrography of Human Chromosomes

Research on human cytogenetics began with the work of Arnold (1879) and Fleming (1882) who for the first time examined human mitotic chromosomes. The detailed study of human chromosome morphology began 1956 after Tijo and Levan improved the technique of squash preparation using hypotonic shock and added colchicine to arrest cells in metaphase in order to increase the number of countable cells (Vogel and Motulsky, 1986). In their now classic article they reported that the human chromosome number was 46 and not 48 as was believed from earlier reports. Their work was confirmed in the same year by Ford and Hamerton (1956). The two articles stimulated a renewed interest in human cytogenetics and soon several laboratories were engaged in the study of human chromosomes and a variety of classification and nomenclature systems were proposed. This resulted in confusion in the literature and a need to establish a common system of nomenclature that would improve communication between workers in the field (Harnden, 1985). 1960 “A proposed standard system of nomenclature of human mitotic chromosomes“ was reported by a study-group which convened in Denver, Colorado. This report, more usually known as the Denver Conference (1960), has formed the basis for all subsequent nomenclature reports. The present human chromosome nomenclature (ISCN 1995) is based on the results of the following international conferences: Denver 1960, London 1963, Chicago 1966, Paris 1971, Paris 1975, Stockholm 1977, Paris 1981, Memphis 1994.

In 1956 the biomedical world was surprised to hear a report that human cells each contained forty six chromosomes, rather than the forty eight count that had been documented since the 1920s. Application of available techniques to culture human cells in vitro, halt their division at metaphase, and disperse chromosomes in an optical plane permitted perception of visual images not seen before. Researchers continued to obtain the preconceived forty eight counts until reeducation with these novel epistemic ‘chromosomes’ convinced them that they could confidently report forty six chromosomes per cell. Within only a few years, and virtually without dissent, the social community of human cytogeneticists agreed upon a shared visual culture of human chromosome count and morphology. The initial forty six count proved not to be an anomaly. A new comparison of historical and ethnomethodological studies has suggested a better understanding of how applied technologies coupled with altered human perceptions established a new science. Human cytogenetics then collaborated with medical genetics to correlate changes in the new human karyotype with disorders of clinical significance.

Before 1956 two “facts” were known about human cytogenetics. The human chromosome number was believed to be 48, and the XX-XY mechanism of sex determination was assumed to work in the same way as it does in Drosophila. Studies of the fruit fly had shown that the ratio of the number of X chromosomes to the number of sets of autosomes determines the sex of the organism. Both these fundamental notions about human chromosomes were eventually proved wrong.

Distinct cell-cycle-dependent changes in the conformation of centromeric chromatin in a specific human chromosome containing alpha-satellite DNA have been demonstrated by fluorescence in situ hybridization (FISH). This method, based upon specific FISH signal morphology, allows simultaneous analysis of chromosomal aneuploidy and detection of specific cell-cycle stage(s) of human tumor and/or normal cell populations in a single preparation of interphase cells. This interphase cytogenetic procedure might prove useful for both basic and clinical research involving human cells.

Development of technology can allow access to new regimes in science and creation of new fields of research. The development of ultra-high finesse mirror technology enabled the development of the field of cavity quantum electrodynamics, and an abundance of wonderful physics experiments soon followed. The sophistication of the field of nano-fabrication and nano-photonics would allow unprecedented capability to mold the shape and flow of light, and provide a novel platform for efficient and hopefully integrable quantum systems. In this project, we hope to interface cold atoms, perhaps the most quintessential of quantum systems, to the engineering power of nano-photonics. We believe this field of study will not only lead to the demonstration of new physics in the quantum regime, but work toward building a network with quantum capabilities mediated by optical channels. In this project, we develop a nano-fabricated platform capable of interfacing nano-photonic devices with cold Cesium atoms in free-space. Nano-photonic waveguide devices are fabricated in a Silicon Nitride device layer on Silicon substrate. The fabrication is compatible with conventional semiconductor fabrication processes, and the chip design has been adapted to allow incorporation with free-space optics to support cold Cesium atom cloud around the waveguides. An ultra-high vacuum system that is compatible to the chip and its supporting structures was constructed to perform experiments. With our system, we were able to fabricate and characterize nano-photonic structures, including 1D photonic crystal waveguides, cavities, and 2D photonic crystal slabs. For the 1D photonic crystal waveguide devices, enhanced atom-light coupling between localized Cesium atoms in the vicinity of the devices, and also atom-atom interaction between Cesium atoms mediated by the guided mode of the photonic crystal waveguide, has been observed. The 2D photonic devices allow us many capabilities beyond that of the 1D waveguide. Demonstration of exotic optical properties including natural decay rate suppression and circular polarization engineering, should be within reach in the near future.

We depend upon the olfactory abilities of dogs for critical tasks such as detecting bombs, landmines, other hazardous chemicals and illicit substances. Hence, a mechanistic understanding of the olfactory system in dogs is of great scientific interest. Previous studies explored this aspect at the cellular and behavior levels; however, the cognitive-level neural substrates linking them have never been explored. This is critical given the fact that behavior is driven by filtered sensory representations in higher order cognitive areas rather than the raw odor maps of the olfactory bulb. Since sedated dogs cannot sniff, we investigated this using functional magnetic resonance imaging of conscious dogs. We addressed the technical challenges of head motion using a two pronged strategy of behavioral training to keep dogs' head as still as possible and a single camera optical head motion tracking system to account for residual jerky movements. We built a custom computer-controlled odorant delivery system which was synchronized with image acquisition, allowing the investigation of brain regions activated by odors. The olfactory bulb and piriform lobes were commonly activated in both awake and anesthetized dogs, while the frontal cortex was activated mainly in conscious dogs. Comparison of responses to low and high odor intensity showed differences in either the strength or spatial extent of activation in the olfactory bulb, piriform lobes, cerebellum, and frontal cortex. Our results demonstrate the viability of the proposed method for functional imaging of the olfactory system in conscious dogs. This could potentially open up a new field of research in detector dog technology.

Nanotechnology could be a very important field of recent research dealing with medical, industrial, environment. Silver nanoparticles are the topics of researchers because of their distinctive properties (size, shape depending optical, antimicrobial, and electrical properties). The synthesis of safe nanoparticles by biological organisms is recommended due to the environmental friendliness and low costs compared to physical and chemical methods. Recently, researchers tend to use a biological synthesis of nanoparticles by biological methods such as plants. This research aimed to study on the rainfall level on the biosynthesis of silver nanoparticles by Lamiaceae family plants in different regions of Iran. T-test student was used to examining the relationship between the size of nanoparticles and rainfall, using spss version 22 software. The study shows phenol concentration in low rainfall areas is more than high rainfall area, which is the main factor for the synthesis of nanoparticles. The result of the study demonstrated that the highest size of synthesized nanoparticle is 50 nm and the lowest size 10 nm, which are related to high rainfall and low rainfall regions respectively. The results showed the relationship between synthetic nanoparticles sizes and rainfall are significant p-value

Spontaneous retinal venous pulsations(SVPs) appears in 90％ of normal persons.It is seen as a rhythmic subtle narrow and expansion of one or more retinal veins on the optic disc.Many researches have demonstrated that SVPs could be applied to the intracranial pressure(ICP) monitoring as well as diagnoses and fellow up of glaucoma.But there is no corresponding domestic research in this field up to now.Although the physiological mechanism of the venous pulsations has been the point of much debate,its potential clinical value attract our attention.The present paper reviewed the progress in current understanding of the mechanism behind the SVPs,the examination method and application of SVPs in clinical study. Key words: Spontaneous retinal venous pulsation; Intracranial pressure; Glaucoma

Oftentimes cells are removed from the body for disease diagnosis or cellular research. This typically requires fluorescent labeling followed by sorting with a flow cytometer; however, possible disruption of cellular function or even cell death due to the presence of the label can occur. This may be acceptable for <i>ex vivo</i> applications, but as cells are more frequently moving from the lab to the body, label-free methods of cell sorting are needed to eliminate these issues. This is especially true of the growing field of stem cell research where specialized cells are needed for treatments. Because differentiation processes are not completely efficient, cells must be sorted to eliminate any unwanted cells (<i>i.e</i>. un-differentiated or differentiated into an unwanted cell type). In order to perform label-free measurements, non-linear optics (NLO) have been increasingly utilized for single cell analysis because of their ability to not disrupt cellular function. An optical system was developed for the measurement of NLO in a microfluidic channel similar to a flow cytometer. In order to improve the excitation efficiency of NLO, a scanned Bessel beam was utilized to create a light-sheet across the channel. The system was tested by monitoring twophoton fluorescence from polystyrene microbeads of different sizes. Fluorescence intensity obtained from light-sheet measurements were significantly greater than measurements made using a static Gaussian beam. In addition, the increase in intensity from larger sized beads was more evident for the light-sheet system.

Although organic petrology and organic geochemistry differ greatly in age, it is during the last 25 years that there has been an almost exponential expansion of research and literature in both fields. Much of the support for the developments that have taken place has come from industrial sources. The steel industry underpinned applied coal petrology in the 1960s to improve carbonization practice related to the production of metallurgical cokes. The petroleum industry has generally supported both organic petrology and organic geochemistry, with a principal aim of improving methods to assess rank (level of maturity) and type (source input) of both coals and kerogens. As precise a determination as possible of both these parameters is as essential in hydrocarbon-prospect appraisal as it is in the raising of coke quality. In organic petrology the construction of fully automated microscope fluorometric systems has been a major advance that has helped to define more precisely the low maturity levels that exist prior to and through most of the ‘oil window’. The same optical systems have not been so successful in producing an acceptable single petrographic typing method for kerogens. Used in conjunction with chemical methods, however, microscope fluorometry has certainly contributed substantially towards more precise kerogen typing, allowing more satisfactory discrimination of the liptinite macerals, several of which are known ‘oil formers’. Another group of potentially economic rocks, the oil shales, has also been successfully classified, principally through fluorescence methods. Within organic geochemistry, the growth and application of analytical pyrolysis methods have been of relevance and importance. While not capable of high chemical resolution, bulkflow pyrolysis systems ( cf. ‘Rock-Eval’) are now widely used to gain a preliminary estimation of maturity level, source input and generating potential of source rocks by the screening of large numbers of samples. The most important single advance in the pyrolysis field, however, has probably been the evolution of a typing method, which, although it utilizes information from both petrography and bulk-flow pyrolysis has, as its essential core, quantitative high-resolution pyrolysis data. Kerogens can now be subdivided into eight different end-members and referred to specific depositional environments. When these fluorometric and pyrolysis data are combined with information from biological-marker studies, which have expanded rapidly as a result of the advances in computerized gas chromatography-mass spectrometry over the past decade, it is not surprising that hydrocarbon exploration efforts are better rewarded. There is now less doubt that terrestrial sources have generated economic accumulations of oil. The principal areas where oil has been generated from land-plant material are the Australian and the Canadian Frontier sedimentary basins, and the Chinese intermonbane basins, but other similar environments have been identified and no doubt other basins with terrigenous, oil-forming source rocks will be discovered in the future. For further rapid advances in microscopic fluorometry in organic petrology a thorough understanding of the underlying chemistry will be important. Although pyrolysis-gc systems will continue to contribute to kerogen typing, surely the principal competitor (and further stimulus) to petrographic typing methods will be pyrolysis-ms. Close collaboration between investigators in the two fields is essential. A serious reexamination of the prospects for laser-micropyrolysis systems in kerogen typing, first mooted more than 20 years ago, but then unsatisfactory because the ‘state of the art’ in both microscope optics and in laser and mass spectrometer technology was insufficiently refined, should be considered. Continuing sophistication and success in the detection, identification and application of biomarkers will result from the use of a variety of techniques, for example, tandem mass spectrometry, high performance liquid chromatography-mass spectrometry and gas chromatography-isotope mass spectrometry. Selected metastable ion monitoring and high-resolution gc-ms seems an inevitable core procedure for the specific identification of biomarkers in the future, probably replacing current conventional gc-ms systems.

Due to their merits of low areal density, in-orbit deploying and low manufacturing cost properties, membrane-like deformable mirrors meet the ultra-lightweight and large aperture demand of space optical mirror systems well. Membrane-like mirrors has therefore become a hot spot in the field of space science research now. Surface of these in-orbit membrane-like structures are susceptible to external environment variation on account of their low stiffness and high flexibility properties. Once excited by external excitations, the membrane vibration endures and this would not only degrade its performance, but also lead to system or structural failures. So dynamic vibration control of the membrane-like mirror is indispensable. When the orbiting mirror passes from Earth’s shadow into sunlight, the surface temperature of the mirror changes and this will render membrane thermal distortion. Hence, quasi-static surface error adjustment of the mirror is also requisite. In this paper, a 0.2m diameter scaled-down Kapton membrane-like mirror is taken as the experiment subject. Polyvinylidene Fluoride (PVDF) patches are laminated on the non-reflective side of the mirror as in-plane actuators. High precision laser displacement sensors are used to measure the surface deviation of the mirror. A modal vibration control system based on the positive position feedback (PPF) algorithm and a quasi-static surface control system based on the proportional error feedback algorithm are established respectively. Several mirror control experiments are performed and the results indicate that the methods proposed could suppress the membrane vibration and alleviate the membrane thermal deformation effectively.

Polyethylene is often used as the outer protective layer of optical cables due to its excellent dielectric, corrosion resistance, and mechanical properties. However, when facing high-voltage optical cable lines, its insulation ability is slightly insufficient. Therefore, a new type of optical cable sheath has been studied and prepared. This sheath is suitable for optical cable systems with voltage levels of 10 kV and below, and can meet the insulation and protection requirements in power communication scenarios. Firstly, different forms of magnesium oxide were prepared by hydrothermal and redox methods, and added to a polyethylene solution. The magnesium oxide/polyethylene composite film was prepared by a solution casting process with thermal crosslinking at 180°C for 15 min. To further improve the performance of composite films, a new type of optical cable sheath material, magnesium oxide/polyethylene composite film, was prepared by combining high thermal conductivity alumina with fibrous magnesium oxide/polyethylene. The results showed that when the amount of fibrous magnesium oxide in different forms of magnesium oxide/polyethylene composite films was 1.5 phr, the breakdown strength could reach 468 kV/mm, which was 26.49% higher than that of pure polyethylene, and the dielectric capacity increased by 5%. The direct current breakdown strength of the alumina/magnesium oxide/polyethylene composite film was 518 kV/mm, which was 14.11% higher than that of the magnesium oxide/polyethylene composite film. The above data indicated that the insulation performance of the modified optical cable sheath was greatly improved, which can adapt to higher voltage optical cable protection. The research provides important references for the design and optimization of new optical cable sheath materials, as well as new ideas and methods for material research in related application fields.

Small nucleolar RNAs in plasma extracellular vesicles and their discriminatory power as diagnostic biomarkers of Alzheimer's disease

The development of innovative materials for sensitive and selective gas sensing is a very relevant field for the current nanotechnology research. A strong effort is dedicated to the fabrication of low-cost and efficient nanoscale devices capable of a fast detection. Resistive electrical devices are the most adopted solutions for in-situ and real-time detection, but their main drawbacks are the low selectivity, response drift, electromagnetic noise dependence and need of contact measurements. Optical gas sensors allow to overcome such limits, and could moreover exhibit thermal and mechanical stability, operate at room temperature, and be integrated on-chip. Within this framework, plasmon-based optical devices are knowing an increasing development and diffusion. Herein plasmonic sensors for aromatic hydrocarbon detection are presented. These systems are based on aryl-bridged polysilsesquioxanes (aryl-PSQs), obtained either \(\textcircled{1}\) coupling such hybrid films with Au nanoparticles (NPs), aiming to the excitation of localized surface plasmon resonances (LSPRs), or \(\textcircled{2}\) depositing them onto metallic waveguiding layers, to form gratings supporting the propagation of surface plasmon polaritons (SPPs). Aryl-PSQs are sol-gel materials characterized by a native controlled porosity and other functionalities (Loy and Shea, Chem Rev 95:1431–1442, 1995; Dabrowski et al., Appl Surf Sci 253:5747–5751, 2007; Brigo et al., Nanotechnology 23:325302, 2012). Temperature programmed desorption investigations of xylene on phenyl-bridged (ph-PSQ) and diphenyl-bridged (diph-PSQ) PSQ films indicate a specific π −π interaction between the organic component of the films and xylene molecules: the interaction energy is quantified in 38 ± 14 kJ/mol and 115 ± 13 kJ/mol, respectively (Brigo et al., J Mater Chem C 1:4252, 2013). For type \(\textcircled{1}\) sensors, a thin film of aryl-PSQ was deposited on a submonolayer of Au NPs coating a fused silica substrate. These sensors were tested monitoring the variation of the LSPRs under cycles of exposure to N2 and to 30 ppm xylene in N2.

Emerging all-optical methods provide unique possibilities for noninvasive studies of physiological processes at the cellular and subcellular scale. On the one hand, superresolution microscopy enables observation of living samples with nanometer resolution. On the other hand, light can be used to stimulate cells due to the advent of optogenetics and photolyzable neurotransmitters. To exploit the full potential of optical stimulation, light must be delivered to specific cells or even parts of cells such as dendritic spines. This can be achieved with computer generated holography (CGH), which shapes light to arbitrary patterns by phase-only modulation. We demonstrate here in detail how CGH can be incorporated into a stimulated emission depletion (STED) microscope for photostimulation of neurons and monitoring of nanoscale morphological changes. We implement an original optical system to allow simultaneous holographic photostimulation and superresolution STED imaging. We present how synapses can be clearly visualized in live cells using membrane stains either with lipophilic organic dyes or with fluorescent proteins. We demonstrate the capabilities of this microscope to precisely monitor morphological changes of dendritic spines after stimulation. These all-optical methods for cell stimulation and monitoring are expected to spread to various fields of biological research in neuroscience and beyond.