Molecular weight characteristics of humic substances from different environments as determined by size exclusion chromatography and their statistical evaluation

Recorded molecular weights (MWs) for humic substances (HS) range from a few hundred to millions of daltons. For purposes of defining HS as a specific class of chemical compounds, it is of particular importance to ascertain if this broad range of MWs can be attributed to actual variability in molecular properties or is simply an artifact of the analytical techniques used to characterize HS. The main objectives of this study were (1)to establish if a preferential range of MWs exists for HS and (2) to determine any consistent MW properties of HS. To reach the goal, we have undertaken an approach to measure under standardized conditions the MW characteristics of a large set of HS from different natural environments. Seventy-seven humic materials were isolated from freshwater, soil, peat, and coal, such that each possessed a different fractional composition: humic acid (HA), fulvic acid (FA), and a nonfractionated mixture of HA and FA (HF). Size exclusion chromatography (SEC) was used as the analytical technique to determine molecular weight characteristics. The MW distributions were characterized by number (Mn) and weight (Mw) average MW, and by polydispersity. The complete range of Mw values varied within 4.7-30.4 kDa. The maximum Mw values were observed for peat HF and soil HA, whereas the smallest weights were measured for river water HF. Maximum values of polydispersity (3.5-4.4) were seen for peat HF and soil HA, while much lower values (1.6-3.1) were found for all preparations isolated with XAD-resins. Statistical evaluation showed consistent Mw and Mn variations with the HS source, while polydispersity was mostly a function of the isolation procedure used. A conclusion was made that HS have a preferential range of MW values that could characterize them as a specific class of chemical compounds.     

Pick-by-vision: there is something to pick at the end of the augmented tunnel

We report on the long process of exploring, evaluating and refining augmented reality-based methods to support the order picking process of logistics applications. Order picking means that workers have to pick items out of numbered boxes in a warehouse, according to a work order. To support those workers, we have evaluated different HMD-based visualizations in six user studies, starting in a laboratory setup and continuing later in an industrial environment. This was a challenging task, as we had to conquer different kinds of navigation problems from very coarse to very fine granularity and accuracy. The resulting setup consists of a combined and adaptive visualization to precisely and efficiently guide the user even if the actual picking target is not always in the field of view of the HMD.     

Quality Changes of Shrimp (Pandalus borealis) Stored under Different Cooling Conditions

The influence of different cooling techniques and storage temperatures (‐1.5 °C or 1.5 °C) to prolong the shelf life of shrimp was evaluated by sensory analysis, physical methods, chemical analysis, and microbial analysis. Storage in liquid ice was more effective than flake ice or brine mixed with flake ice in delaying spoilage of the shrimp by slowing down microbial growth and formation of total volatile basic nitrogen (TVB‐N) and trimethylamine (TMA). Total viable counts (TVC) showed that bacteria grew most quickly in shrimp stored in flake ice and in brine mixed with flake ice, followed by those in liquid ice at 1.5 °C and ‐1.5 °C, respectively. Lowest counts were observed in shrimp stored in liquid ice at ‐1.5 °C where the lag phase of growth was apparently extended at the beginning of storage. Principal component analysis (PCA) showed a good correlation between quality indicators related to microbial growth, TVC, pH, TVB‐N, TMA, responses of an electronic nose and sensory evaluation.     

Combination of warm water and hydrogen peroxide to reduce the numbers of Salmonella Typhimurium and Listeria innocua on field salad (Valerianella locusta)

The optimal conditions of decontamination of field salad by treatment with warm water containing hydrogen peroxide were determined with the aid of a central composite design. It was the aim to improve the hygienic status while keeping the sensory quality at the highest level possible. Two series of experiments were performed to study the effects of the following parameters: temperature (45–50 °C), H₂O₂ (1–4%) and treatment time (60–210 s). In series 1 the effect on sensory properties and reduction of total aerobic counts was investigated. To determine sensory quality, treated samples stored at 4 °C for 7 days were subjected to evaluation by 15 panelists. Overall visual quality (OVQ), color, texture and odor correlated well with product acceptability (R²=0.934, 0.946, 0.945 and 0.956, respectively), and OVQ was the most sensitive criterion. An acceptability of 75% in OVQ was chosen as the limit and an acceptance area was defined to deduce permitted conditions for decontamination. Within that area a reduction of total counts by 2.64–3.22 and 1.9–3.48 log₁₀ cfu/g was achieved after treatment and storage at 4 °C for 7 days, respectively. In series 2 field salad was inoculated with Listeria innocua and Salmonella Typhimurium and it was observed that within the area of acceptability a reduction of the numbers of the challenge organisms by 1.27–3.26 and 0.79–3.05 log₁₀ cfu/g, respectively, was achieved immediately after treatment, and by 1.64–3.09 (L. innocua) and 1.1–2.63 log₁₀ cfu/g (S. Typhimurium) after storage. The initial decontaminating effect on L. innocua and S. Typhimurium was sustained or even increased after storage, when the salad was treated below 48.9 °C for more than 68 s. Three independent experiments confirmed the reliability of the models of the count reduction of L. innocua and S. Typhimurium.     

Implementation of a virtual correlative light and transmission electron microscope

In the long run, the widespread use of slide scanners by pathologists requires an adaptation of teaching methods in histology and cytology in order to target these new possibilities of image processing and presentation via the internet. Accordingly, we were looking for a tool with the possibility to teach microscopic anatomy, histology, and cytology of tissue samples which would be able to combine image data from light and electron microscopes independently of microscope suppliers. With the example of a section through the villus of jejunum, we describe here how to process image data from light and electron microscopes in order to get one image‐stack which allows a correlation of structures from the microscopic anatomic to the cytological level. With commercially available image‐presentation software that we adapted to our needs, we present here a platform which allows for the presentation of this new but also of older material independently of microscope suppliers. Microsc. Res. Tech. 76:679–686, 2013. © 2013 Wiley Periodicals, Inc.     

Mechanical damage to Gram-negative bacteria by surface plating with the Drigalski-spatula technique

Colony counting by spreading bacterial suspensions on plating media by various techniques is of general concern. Comparative studies between hand plating (Drigalski-spatula technique) for different time intervals and spiral plating resulted in significant differences in colony counts. Lower counts of Gram-negative bacteria were obtained by using hand plating for more than 10 s, compared with short time hand plating (5 s) or spiral plating. Colony counting of Gram-positive bacteria showed no differences between both techniques. Further characterisation of Escherichia coli cells spread with the Drigalski-spatula technique by electron microscopy revealed a large number of damaged cells compared to control samples. The data clearly shows that the mechanical forces during hand plating are sufficient to damage E. coli cells.     

Heme-dependent and heme-independent nitrite reduction by lactic acid bacteria results in different N-containing products

Seventy strains of lactic acid bacteria were investigated for nitrite reductase activity. Two types of this activity were detected. Type I was found in Lactobacillus plantarum, L. pentosus and Pediococcus pentosaceus. This activity is heme-dependent with ammonia as the sole product. Type II mechanism is heme-independent and reduces nitrite to NO and N₂O.     

Immune Aging and Immunotherapy in Cancer

Immune functions decline as we age, while the incidence of cancer rises. The advent of immune checkpoint blockade (ICB) has not only revolutionized cancer therapy, but also spawned great interest in identifying predictive biomarkers, since only one third of patients show treatment response. The aging process extensively affects the adaptive immune system and thus T cells, which are the main target of ICB. In this review, we address age-related changes regarding the adaptive immune system with a focus on T cells and their implication on carcinogenesis and ICB. Differences between senescence, exhaustion, and anergy are defined and current knowledge, treatment strategies, and studies exploring T cell aging as a biomarker for ICB are discussed. Finally, novel approaches to improve immunotherapies and to identify biomarkers of response to ICB are presented and their potential is assessed in a comparative analysis.