Automated property verification for large scale B models with ProB

In this paper we describe the successful application of the ProB tool for data validation in several industrial applications. The initial case study centred on the San Juan metro system installed by Siemens. The control software was developed and formally proven with B. However, the development contains certain assumptions about the actual rail network topology which have to be validated separately in order to ensure safe operation. For this task, Siemens has developed custom proof rules for Atelier B. Atelier B, however, was unable to deal with about 80 properties of the deployment (running out of memory). These properties thus had to be validated by hand at great expense, and they need to be revalidated whenever the rail network infrastructure changes. In this paper we show how we were able to use ProB to validate all of the about 300 properties of the San Juan deployment, detecting exactly the same faults automatically in a few minutes that were manually uncovered in about one man-month. We have repeated this task for three ongoing projects at Siemens, notably the ongoing automatisation of the line 1 of the Paris Métro. Here again, about a man month of effort has been replaced by a few minutes of computation. This achievement required the extension of the ProB kernel for large sets as well as an improved constraint propagation algorithm. We also outline some of the effort and features that were required in moving from a tool capable of dealing with medium-sized examples towards a tool able to deal with actual industrial specifications. We also describe the issue of validating ProB, so that it can be integrated into the SIL4 development chain at Siemens.     

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

The short and medium range structure of glassy MoO₃–ZnO–B₂O₃ has been studied by neutron diffraction and reverse Monte Carlo simulation. The partial atomic pair correlation functions and coordination numbers are presented that are not yet reported for this system. We have established that the first neighbor distances do not depend on concentration within limit of error, the actual values are r_B‐O = 1.38 Å, r_Mo‐O = 1.72 Å, and r_Zn‐O = 1.97 Å. It is found that ZnO takes part in the glassy structure as network former, as ZnO₄ tetrahedral are linked both to MoO₄ and to BO₃ and BO₄ groups. It is revealed that BO₄/BO₃ increases with increasing B₂O₃ content. We have found that only small amount of boroxol ring is present, BO₃ and BO₄ groups are organized into superstructure units, and a small part is in isolated BO₃ triangles. The BO₃ and BO₄ units are linked to MoO₄ or ZnO₄ forming mixed ^[4]Mo‐O‐^[3]B, ^[4]Mo‐O‐^[4]B, ^[4]Mo‐O‐^[4]Zn, ^[3]B‐O‐^[4]Zn, ^[4]B‐O‐^[4]Zn bond linkages.     

Modulation of silica layer properties by varying the granulometric state of tetraethyl orthosilicate precursor aerosols during combustion chemical vapor deposition (CCVD)

Abstract

For the purpose of silica surface layer modulation, a pneumatic-controlled two-substance atomizer with inertia-based coarse droplet separation was operated at different system pressures for tetraethyl orthosilicate precursor aerosol supply during combustion chemical vapor deposition. A comprehensive testing study was performed to characterize the atomizer’s performance characteristics, initial precursor aerosols at the atomizer’s outlet, transformed aerosols before combustion, combustion aerosols and formed layers. Laser diffraction spectrometry, differential electrical mobility analyses and condensation particle counting were used for aerosol characterization with regard to particle size and particle production quantities. Layers were characterized by scanning electron microscopy, atomic force microscopy, spectral ellipsometry, water contact angle measurements and light transmission concerning geometric properties (thickness, surface structure and roughness) and physical behaviors (i.e., optical behaviors, hydrophobicity). Results show a quasi-linear relationship of the ejection mass flow of the pneumatic-controlled atomizer and geometric layer properties which again show a direct relationship to the physical properties. No correlation was found between the aerosols before combustion and the combustion aerosols since the majority of combustion aerosol particles are synthesized solely from the gas phase based on evaporated precursor material.

Copyright © 2020 American Association for Aerosol Research     

BSA Hydrogel Beads Functionalized with a Specific Aptamer Library for Capturing Pseudomonas aeruginosa in Serum and Blood

Systemic blood stream infections are a major threat to human health and are dramatically increasing worldwide. Pseudomonas aeruginosa is a WHO-alerted multi-resistant pathogen of extreme importance as a cause of sepsis. Septicemia patients have significantly increased survival chances if sepsis is diagnosed in the early stages. Affinity materials can not only represent attractive tools for specific diagnostics of pathogens in the blood but can prospectively also serve as the technical foundation of therapeutic filtration devices. Based on the recently developed aptamers directed against P. aeruginosa, we here present aptamer-functionalized beads for specific binding of this pathogen in blood samples. These aptamer capture beads (ACBs) are manufactured by crosslinking bovine serum albumin (BSA) in an emulsion and subsequent functionalization with the amino-modified aptamers on the bead surface using the thiol- and amino-reactive bispecific crosslinker PEG₄-SPDP. Specific and quantitative binding of P. aeruginosa as the dedicated target of the ACBs was demonstrated in serum and blood. These initial but promising results may open new routes for the development of ACBs as a platform technology for fast and reliable diagnosis of bloodstream infections and, in the long term, blood filtration techniques in the fight against sepsis.     

Surface chemistry of phosphorus-containing carbons of lignocellulosic origin

Activated carbon adsorbents were prepared by phosphoric acid activation of fruit stones in an argon atmosphere at various temperatures in the 400-1000 °C range and at different acid/precursor impregnation ratios (0.63-1.02). The surface chemistry of the carbons was investigated by elemental analysis, cation exchange capacity (CEC, measured by neutralization of NaOH with acidic surface groups), infrared spectroscopy and potentiometric titration. Porous structure was derived from adsorption isotherms (N₂ at −196 °C and CO₂ at 0 °C). It was demonstrated that all carbons show considerable cation exchange capacity, the maximum (CEC = 2.2 mmol g⁻¹) being attained at 800 °C, which coincides with the maximum contents of phosphorus and oxygen. The cation exchange properties of phosphoric acid activated carbons from fruit stones are chemically stable in very acidic and basic solutions. Proton affinity distributions of all carbons show the presence of three types of surface groups with pK at 2.0-3.3, 4.6-5.9 and 7.6-9.1. These pK ranges were ascribed primarily to: (a) phosphorus-containing and carboxylic groups; (b) lactonic groups, and (c) phenolic groups, respectively. Phosphoric acid activated carbons are microporous with a relatively small contribution of mesopores. A maximum BET surface area of 1740 m² g⁻¹ was attained at 400 °C.     

Disziplinäre Nichtkonsolidierung

Disciplinary Non-Consolidation. On the Origins of Medieval Archaeology in the 1920s and the 1930s. This article investigates the roots of the sub-discipline medieval archaeology that emerged in German-speaking universities in the 1950s and 1960s. In the 1930s, research practices crucial for the formation of medieval archaeology, such as the investigation of medieval castles and peasant houses, became more prominent in the humanities, especially in the context of völkisch research. After the Nazis took power in Germany, they encouraged such research because it built a scientific basis for their nationalist policy. This politically motivated funding did not result in a new discipline, in contrast to research fields such as prehistory and folklore studies. In this article, I propose two explanations for why medieval archaeology did not emerge as an interdisciplinary research field in the 1930s and 1940s, even though the course was set for its development. First, for archaeologists, art historians, and regional medieval historians, research objects such as medieval castles were semantically too indeterminate. Archaeologists would investigate a castle as a building completely destroyed and buried under rubble, while art historians would be interested in its building technique, and regional medieval historians in its written record. Second, disciplines that were important for the creation of medieval archaeology, such as prehistoric archaeology, art history, and regional medieval history, structurally did not allow for the emergence of an interdisciplinary research field in the 1930s. In particular, prehistoric archaeology, which was crucial for the development of medieval archaeology, itself was not fully institutionalized at universities in the 1930s. This institutionalization process prevented the emergence and development of an interdisciplinary research field such as medieval archaeology. To demonstrate this argument, I draw on two examples of investigations of castles, one in Nazi Germany and the other in the German-speaking part of Switzerland.     

Modelling HIV-1 2-LTR dynamics following raltegravir intensification

A model of reservoir activation and viral replication is introduced accounting for the production of 2-LTR HIV-1 DNA circles following antiviral intensification with the HIV integrase inhibitor raltegravir, considering contributions of de novo infection events and exogenous sources of infected cells, including quiescent infected cell activation. The model shows that a monotonic increase in measured 2-LTR concentration post intensification is consistent with limited de novo infection primarily maintained by sources of infected cells unaffected by raltegravir, such as quiescent cell activation, while a transient increase in measured 2-LTR concentration is consistent with significant levels of efficient (R₀ > 1) de novo infection. The model is validated against patient data from the INTEGRAL study and is shown to have a statistically significant fit relative to the null hypothesis of random measurement variation about a mean. We obtain estimates and confidence intervals for the model parameters, including 2-LTR half-life. Seven of the 13 patients with detectable 2-LTR concentrations from the INTEGRAL study have measured 2-LTR dynamics consistent with significant levels of efficient replication of the virus prior to treatment intensification.     

Wann sind Lieferaufträge profitabel?

The paper aims to optimize the final part of a firm’s value chain with regard to attended last-mile deliveries. It is assumed that to be profitable, e-commerce businesses need to maximize the overall value of fulfilled orders (rather than their number), while also limiting costs of delivery. To do so, it is essential to decide which delivery requests to accept and which time windows to offer to which consumers. This is especially relevant for attended deliveries, as delivery fees usually cannot fully compensate costs of delivery given tight delivery time windows. The literature review shows that existing order acceptance techniques often ignore either the order value or the expected costs of delivery. The paper presents an iterative solution approach: after calculating an approximate transport capacity based on forecasted are accepted or rejected expected delivery requests and a cost-minimizing routing, actual delivery requests aiming to maximize the overall value of orders given the computed transport capacity. With the final set of accepted requests, the routing solution is updated to minimize costs of delivery. The presented solution approach combines well-known methods from revenue management and time-dependent vehicle routing. In a computational study for a German metropolitan area, the potential and the limits of value-based demand fulfillment as well as its sensitivity regarding forecast accuracy and demand composition are investigated.