Biofilm reactors in anaerobic wastewater treatment

Attached biofilm reactors provide the means for implementing energy-efficient anaerobic wastewater treatment at full scale. Progress has been made in the development of fixed, expanded and fluidized bed anaerobic processes by addressing fundamental reactor design issues. Several new biofilm reactor concepts have evolved from recent studies.     

Fixed bed porous glass sphere (porosphere) bioreactors for animal cells

Process intensity of fixed bed glass sphere culture systems is increased considerably by replacing solid glass spheres with open pore glass spheres. This technique demonstrates the possibility of having a system capable of both volumetric and cell density scale up and being suitable for substrate attached and suspension cells. The yields achieved for a number of attached cell lines (approximately 10⁷/ml) demonstrate an increase approaching one order of magnitude over solid glass spheres (approximately 10⁶/ml). Also suspension cells were successfully entrapped in the open pore structure with similar yields.     

A periodicity result for a nonlinear functional integral equation

In this paper, we study the effect of introducing a delay in a model of cell proliferation considered originally by O. Arino and M. Kimmel (J. Math. Biol. 27, 341–354 (1989)). We prove that slow oscillations take place and periodic oscillations appear for appropriate values of a parameter.     

The membrane dialysis bioreactor with integrated radial-flow fixed bed —a new approach for continuous cultivation of animal cells

A hybridoma cell was cultivated continuously in a membrane dialysis bioreactor with an integrated radial-flow fixed bed consisting of porous Siran^® carriers over a period of 6 weeks. Antibodies accumulated to an average of 100 mg l^?1, approx. 10 times more than in fixed bed cultures without dialysis membrane. Serum costs could be reduced about 85% due to an appropriate feeding strategy. Siran^® carriers with 3–5 mm diameter showed an advantage compared to those with 1–2 mm diameter. For the 3–5 mm carrier the specific glucose uptake rate and the MAb production rate were constant, if the velocity was between 0.09 mm s^?1 and 0.75 mm s^?1. At higher velocities cells are washed out of the bed. Furthermore antibody consistency and cell stability were verified in long-term cultivations over a period of 96 days. From an estimation of the antibody concentration reachable with the reactor concept under optimal conditions a concentration 45 times higher compared to axial-flow fixed bed reactors and 11 times higher compared to stirred tank reactors can be expected.     

A Simple Numerical Procedure for Estimating the Prior Probability in the Biomathematical Proof of Paternity

This note gives a simple procedure for finding the maximum likelihood estimate of the prior probabilities in paternity cases. The procedure is based on a fixed point principle.     

Improvement of Nonradioactive DNA in Situ Hybridization

With the introduction of microwave pretreatment, the quality of nonradioactive in situ hybridization (NISH) using DNA probes on formalin fixed tissue has significantly improved. Even after microwave treatment, however, there are cases where NISH results remain unsatisfactory. Therefore, we tried to improve NISH by testing other buffer systems as alternatives to the citrate buffer that is routinely applied during microwave pretreatment. By using buffer systems originally designed for immunohistochemistry, we significantly improved our NISH results. Difficult tissue samples were more accessible to NISH using these alternative buffer systems and made the quantitative evaluation easier. These results may also be of interest for combined applications of NISH and immunohistochemistry.     

Over‐Expression of RNA Processing,Heat Shock,and DNA Repair Proteins in Breast Tumor Compared to Normal Tissue

This study identifies the main changes in protein expression in human breast tumors compared to normal breast tissue. Malignant tumors (32) and normal breast tissue samples (23), from formaldehyde‐fixed, paraffin‐embedded specimens are subjected to discovery proteomics using liquid chromatography/tandem mass spectrometry, with spectral counts for quantitation. The dataset contains 1406 proteins. Differential expression is measured using a method that takes advantage of estimates of the percentage of tumor on a slide. This analysis shows that the major classes of proteins over‐expressed by tumors are RNA‐binding, heat shock and DNA repair proteins. RNA‐binding proteins, including heterogeneous nuclear ribonucleoproteins (HNRNPs), SR splice factors (SRSF) and elongation factors form the largest group. Comparison with results from another study demonstrates that the RNA‐binding proteins are associated specifically with malignant transformation, rather than with cell proliferation. HNRNP and SRSF proteins help define splice sites in normal cells. Their over‐expression may dysregulate splicing, which in turn has the potential to promote malignant transformation.     

宁夏东部风沙区固定沙丘土壤性质小尺度空间变异特征

随着流动沙丘的不断固定,不同地形部位的土壤机械组成、有机碳(SOC)和全氮(TN)含量的变化存在差异。为了探明固定沙丘的土壤机械组成与土壤养分空间变异特征,本研究以宁夏黄沙古渡固定沙丘为对象,分析了固定沙丘不同部位、不同土层的风沙土机械组成、SOC和TN特征。结果表明: 各土层土壤机械组成均以中沙和细沙为主。SOC和TN有明显的表聚作用,SOC和TN含量最大值分别为5.781和0.412 g·kg^-1,分布在丘间地,脊线和背风坡含量最少。随着土层深度的增加,背风坡和迎风坡的SOC含量逐渐减少,丘间地的SOC含量先减少后增加。SOC和TN在小尺度上均表现出明显的空间异质性;SOC和TN与粉沙和极细沙含量呈显著正相关,与中沙和粗沙含量呈显著负相关。土壤机械组成对SOC和TN含量有明显影响,而且SOC和TN含量随着细颗粒含量的增加而增加,表明土壤细颗粒对有机质的吸附和积累起着重要作用。