Long term stability of silicon roughness standards

In 1986 the roughness reference standards made of silicon were produced at the Laboratory for Precise Measurements of Length (LFSB), which is now a part of Croatian Metrology Institute (HMI) designated as HMI/FSB-LPMD. At that time, roughness standards were commonly made either from steel or glass.After 3 decades of use it was decided to conduct a research of metrological features on two silicon roughness standards which were continuously used as primary standards for roughness in Croatia.The analysis is based on measurement results of roughness parameters (Ra, Rz and RSm) from calibration certificates provided by several national metrology institutes.Statistical consistency is checked with Birge ratio test, and En values are calculated in order to check if significant change of roughness parameters over the years can be determined.     

Sectioning of Epon blocks in the 20 m to 60 micromicron range for histological studies.

Thick sections of tissue, (20 micron--60 micron), are useful in studying the relationship between individual large cells and cell layers in organized neural structures. The ability of the Nomarski Differential Interference-Contrast Microscope to bring a single thin layer into sharp focus makes the examination of such sections feasible. Although celloidin is the classical embedding medium for large, thick sections of neural tissue, the time necessary for this preparation is most inconvenient. Epon is an excellent embedding medium; however, it is extremely hard and brittle. By heating the Epon block face, thick sections can be cut. To avoid the cumbersome, often detrimental use of heat, a modification of this technique was found. Epon blocks, trimmed to a 1 millimeter square face, may be sectioned at room temperature on the sliding microtome at 20 micron to 60 micron with ease. The simple method of preparing such sections is described.     

考虑长远利益的机械零件可靠性优化设计

以零件的失效损失期望作为长远利益指标,建立了既考虑当前利益（制造成本）又考虑长远利益（损失期望）的机械零件可靠性优化设计模型,并给出了求解方法。     

Long term plumb-line alignment of precise measuring instruments: an adaptive digital controller designed for an autoleveling platform

Plumb-line alignment can affect the sensors of precise scientific instruments. When its effect is one of the main contributors to the measurement uncertainty, the deviation from the true vertical must be continuously monitored or compensated. This paper describes a digital control system designed and tested for an autoleveling platform. Best performances are obtained with an adaptive digital compensator based on a convolution of the error signal. Although accuracy and resolution of the leveling transducer limit the ultimate sensitivity, laboratory tests showed that the controller kept for several hours the base-plate top within ±1?μrad. These performances are suitable for maintaining the alignment of relative spring gravimeters used by volcanologists in long-term gravity measurements.     

Long term immunological perturbations post DAA therapy in chronic HCV/HIV co-infected patients

Direct-acting antiviral (DAA) therapies are efficacious for the achievement of sustained virologic response (SVR) in almost all treated hepatitis C virus (HCV)-infected patients. However, the impacts of HCV eradication on immune function and chronic immune activation in the long-term remain controversial and limited, especially in patients co-infected with human immunodeficiency virus (HIV). Indeed, although restoration of many immune responses clearly can be observed, several features of immune perturbations persist over time after HCV clearance. Understanding the degree and reasons of the partial recovery of the immune system in chronic HCV/HIV co-infection after HCV elimination is pivotal to avoid disease progression and possible long-term clinical outcomes in cured patients, as well as contributing to the development of immunotherapy drug design.     

A simple apparatus for controlled pressure perfusion fixation.

An apparatus is described for vascular perfusion of small animals with fixative solutions which while simple and inexpensive allows quantitative and reproducible pressure control. Direct measurement of outflow pressure demonstrated that a sphygmomanometer used to supply external pressure to a plastic blood transfer pack achieved these features. Reproducibility of pressure was maintained by filling the bag with air between perfusions, or when smaller volumes of fixative solution were needed. Rodent brains from fetal to adult ages, and other animals of similar size, have been reliably well fixed by this method.     

Digital stain separation for histological images

It is often desirable to perform digital image analyses on sections prepared for human interpretation, e.g. nuclear chromatin texture analysis or three-dimensional reconstructions using sections requiring human delineation of structures of interest. Unfortunately such analyses are often more effective using stains with less complex contrast. Here an automated selective 'de-staining' method for digital images is presented. The method separates an image into its red, green and blue and hue, saturation and intensity components. A mask of stained tissue is prepared by automatic percentile thresholding. A single weighted inverted colour channel is then added to each of the three primary colour channels separately by an iterative algorithm that adjusts the weights to give minimum variance within the mask. The modified red, green and blue channels are then recombined. This method is automatic requiring no pre-definition of stain colours or special hardware. The method is demonstrated to 'de-stain' nuclei in haematoxylin and eosin (H&E) sections (and a separate haematoxylin image can be derived from this). An image of isolated brown reaction product is produced with immunoperoxidase preparations counterstained with haematoxylin. Furthermore trichrome (haematoxylin van Gieson, picrosirius red) and other common stains may be separated into their components with modifications of the same algorithm. Although other methods for colour separation do exist (e.g. spectral pathology and colour deconvolution) these require special apparatus or precise calibration and foreknowledge of pure dye colour spectra. The present method of digital stain separation is fully automatic with no such prerequisites.     

The avian erythrocyte: a study of fixation for electron microscopy.

The quality of ultrastructural preservation of the avian erythrocyte achieved using various fixation techniques is evaluated. Different combinations of initial fixatives, buffers and post-fixation procedures were tested as well as variations in fixative osmolarity, pH and temperature. Of the commonly used initial fixatives (glutaraldehyde, acrolein and formaldehyde), 2% glutaraldehyde, alone in a slightly hypertonic buffer containing divalent ions, produced optimum erythrocyte preservation. The osmolarity was balanced using a non-electrolyte such as a sucrose. The addition of 12% hexylene glycol to the buffer solutions also improves erythrocyte preservation, as evidenced by the increased stability of the marginal microtubules, microfilaments and proteinaceous material. The use of Spurr low-viscosity epoxy resin enables the cells to be collected using low gravitational centrifugation.     

细长轴的加工

针对细长轴的加工，设计了加工工艺、切削刀具和切削参数，试验结果表明，优化切削工艺、切削参数，可以减少细长轴加工中的变形，提高细长轴加工质量。     

Long term diazotrophic cultivation induces phycobiliprotein production in <i>Anabaena variabilis</i> IMU8

Cyanobacteria are considered as a sustainable feedstock for the production of biochemically activecompounds such as phycobiliproteins (PBPs). In this study, the impact of nitrogen (N) and phosphorus (P) availabilityon PBP production of “N-free acclimated” Anabaena variabilis IMU8 was analyzed. Upon isolation and identification,the cyanobacterium has been maintained in N-free BG-11 medium for more than 20 months. For experimentation, thestrain was incubated in N-replete, N-depleted, N-P-depleted BG-11 medium. Long-term diazotrophic cultivation of A.variabilis IMU8 resulted in elevated PBP productivity with a limited impact on growth. When compared to N-depletedones, N supply stimulated a slight induction of growth and total saccharide production, but total protein content didnot change while PBP production decreased. On the other hand, N-P-depletion resulted in decreased growth rate alongwith reduced total protein and PBP production while rapid induction of total saccharide production was recorded.Fourier transform infrared spectroscopy results refer that membrane-bound oligosaccharides may have regulatory rolesfor PBP production in A. variabilis IMU8 during long term diazotrophic cultivation.