Recent Developments in Noninvasive Techniques for Fresh Fruit and Vegetable Internal Quality Analysis

ABSTRACT: This review covers developments in the field of noninvasive techniques for quality analysis of fresh fruit and vegetables over the past decade up to the year 2005. A chapter on the concept of quality is followed by a discussion of various methods and applications including optical, spectroscopic, and mechanical techniques but also the application of X-rays and some noninvasive methods of minor dispersal. An extra section on research needs reflects on possible future developments. It is concluded that during the last year, much progress has been made in developing nondestructive techniques for the assessment or inspection of quality parameters of fruits including internal disorders but also taste, sugar content, and so forth. As sensors often measure only a single constituent or quality property, combined techniques have to be optimized to measure overall quality. Commercial application of these techniques will be beneficial for the consumer as well as the producer and for trades in which merchants will be able to comply with consumer demands for uniform high-quality products.     

THERMODYNAMIC FUNCTIONS OF THE SOLID-LIQUID TRANSITION OF HYDROCARBON MIXTURES

ABSTRACT

The dependences of the melting temperature and the enthalpy of fusion on the composition are the essential factors for modelling precipitation and solubility of solid hydrocarbons in crude oils and crude oil products. Long-chain iso-alkanes and cyclic alkanes must be considered besides of n-alkanes. Therefore a degree of isomerization and cyclization was defined using the refractive index and the carbon number. The melting temperatures and the enthalpies of fusion of different n-alkanes and fractions of crude oil were determined by differential scanning calorimetry. Both parameters can be correlated with the degree of isomerization and cyclization by a quadratic fuction.     

Microstructure of Nanocrystalline Yttria-Doped Zirconia Thin Films Obtained by Sol–Gel Processing

Nano- and microcrystalline yttria-stabilized zirconia (YSZ) thin films with a dopant concentration of 8.3±0.3 mol% Y₂O₃ were prepared with a variation in grain size by two orders of magnitude. A sol–gel-based method with consecutive rapid thermal annealing was applied to fabricate YSZ films, resulting in about 400 nm YSZ on sapphire substrates. The average grain sizes were varied between 5 nm and 0.5 μm by heat treatment in the temperature range of 650°–1350°C for 24 h. High-resolution (HRTEM) and conventional transmission electron microscopy analyses confirmed specimens—irrespective of the thermal treatment—consisting of cubic ( c -)ZrO₂ grains with nanoscaled tetragonal precipitates coherently embedded in the cubic matrix. Energy-dispersive X-ray spectroscopy and HRTEM on a large number of specimens yielded a homogeneous yttria concentration within the grains and at the grain boundaries with the absence of impurities, i.e. silica at the grain boundaries.     

Observation of intrinsic magnetic domains in C60 polymer

A C₆₀ polymer has been characterized for the first time with respect to impurity content and ferromagnetic properties by laterally resolved particle induced X-ray emission (PIXE), superconducting quantum interference device (SQUID) and magnetic force microscopy (MFM) in order to detect intrinsic ferromagnetic domains. In parts of the pure regions (concentration of magnetic impurities <1 μg/g), we found stripe-domain magnetic images with different orientations of domain magnetization. The size of the regions where magnetic domains were observed is ∼30% of the pure region. All these results reveal that the polymerized C₆₀ sample is a mixture of magnetic and non-magnetic parts and only a fraction of the sample contributes to the ferromagnetism.     

Circulating Noncoding RNAs in Pituitary Neuroendocrine Tumors—Two Sides of the Same Coin

Pituitary neuroendocrine tumors (PitNET) are common intracranial neoplasms. While in case of hormone secreting tumors pituitary hormone measurements can be used for monitoring the disease, in non-functional tumors there is a need to discover non-invasive biomarkers. Non-coding RNAs (ncRNAs) are popular biomarker candidates due to their stability and tissue specificity. Among ncRNAs, miRNAs, lncRNAs and circRNAs have been investigated the most in pituitary tumor tissues and in circulation. However, it is still not known whether ncRNAs are originated from the pituitary, or whether they are casually involved in the pathophysiology. Additionally, there is strong diversity among different studies reporting ncRNAs in PitNET. Therefore, to provide an overview of the discrepancies between published studies and to uncover the reasons why despite encouraging experimental data application of ncRNAs in clinical routine has not yet taken hold, in this review available data are summarized on circulating ncRNAs in PitNET. The data on circulating miRNAs, lncRNAs and circRNAs are organized according to different PitNET subtypes. Biological (physiological and pathophysiological) factors behind intra- and interindividual variability and technical aspects of detecting these markers, including preanalytical and analytical parameters, sample acquisition (venipuncture) and type, storage, nucleic acid extraction, quantification and normalization, which reveal the two sides of the same coin are discussed.     

Assessment of Novel Long‐Lasting Ceria‐Stabilized Zirconia‐Based Ceramics with Different Surface Topographies as Implant Materials

The development of long‐lasting zirconia‐based ceramics for implants, which are not prone to hydrothermal aging, is not satisfactorily solved. Therefore, this study is conceived as an overall evaluation screening of novel ceria‐stabilized zirconia–alumina–aluminate composite ceramics (ZA₈Sr₈‐Ce11) with different surface topographies for use in clinical applications. Ceria‐stabilized zirconia is chosen as the matrix for the composite material, due to its lower susceptibility to aging than yttria‐stabilized zirconia (3Y‐TZP). This assessment is carried out on three preclinical investigation levels, indicating an overall biocompatibility of ceria‐stabilized zirconia‐based ceramics, both in vitro and in vivo. Long‐term attachment and mineralized extracellular matrix (ECM) deposition of primary osteoblasts are the most distinct on porous ZA₈Sr₈‐Ce11_p surfaces, while ECM attachment on 3Y‐TZP and ZA₈Sr₈‐Ce11 with compact surface texture is poor. In this regard, the animal study confirms the porous ZA₈Sr₈‐Ce11_p to be the most favorable material, showing the highest bone‐to‐implant contact values and implant stability post implantation in comparison with control groups. Moreover, the microbiological evaluation reveals no favoritism of biofilm formation on the porous ZA₈Sr₈‐Ce11_p when compared to a smooth control surface. Hence, together with the in vitro in vivo assessment analogy, the promising clinical potential of this novel ZA₈Sr₈‐Ce11 as an implant material is demonstrated.     

Proton beam writing of microstructures in Agar gel for patterned cell growth

A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 μm allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.     

Biomedical research at LIPSION - Present state and future developments

Since its commissioning in 1998 the high energy ion nanoprobe LIPSION has been developed into a versatile tool for a variety of applications in biomedical research. It includes quantitative trace element analysis with sub-micron spatial resolution and 3D-element imaging, as well as 2D- and 3D-microscopy of density distributions. The analytical methods base on particle induced X-ray emission spectrometry (PIXE) and PIXE-tomography, Rutherford backscattering spectrometry (RBS), as well as scanning transmission ion microscopy (STIM) and STIM-tomography.The continuous developments led to improved capabilities for trace element analysis. For sub-micron analysis the spatial resolution could be improved to 0.3 μm for high resolution work and to 0.5 μm for routine analysis. On the other hand, LIPSION was optimized for high sample throughput in quantitative element imaging maintaining a lateral resolution of 1-2 μm. Recently the methods of PIXE- and STIM-tomography of biological specimens have been extended to limited angle tomography to avoid the complicated preparation of free-standing samples.Besides its analytical applications, the nanoprobe is also used for targeted irradiation of living cells with counted single ions for radiobiological research. It is capable of irradiating up to 20,000 cells per hour. Furthermore, we have developed a technique to achieve confined cell growth based on the proton beam writing technique (PBW) and agar. The paper presents an overview of the current biomedical research fields at LIPSION and gives an outlook on prospective developments.