Advantages of the recursive operability analysis in updating the risk assessment

With the introduction of new regulations and sustainable technologies, revamping and upgrading already existing chemical plants is nowadays an important element in the framework of process engineering. Such important modifications must come along in parallel improvement of process safety. In this sense, risk assessment is a tool that should be versatile and easy to update by definition. However, even the most common methods currently used for accidental scenarios identification and risk assessment estimation (such as HazOp) may prove to be very time-consuming when discussing about safety from process modifications. The availability of a reliable and easy-to-update tool for safety engineering is crucial for process industries. In this work, we compare a risk analysis on a chemical plant subject of modifications performed with two different tools: HazOp and FTA vs Recursive Operability Analysis (ROA) and FTA. Both techniques have been applied to a tank dedicated to dust mixing that was subject of process modifications. Both methods come to the same conclusions, highlighting new failures and process criticalities, associated with the introduction of flow alarms and interlocks in case of excessive depressurizing. It is shown that the Recursive Operability Analysis, with its cause-consequence structure tied with process variable interactions, is much more effective in a risk assessment update

A novel ubiquitin mark at the N-terminal tail of histone H2As targeted by RNF168 ubiquitin ligase

Ubiquitination of histones plays a critical role in the regulation of several processes within the nucleus, including maintenance of genome stability and transcriptional regulation. The only known ubiquitination site on histones is represented by a conserved Lys residue located at the C terminus of the protein. Here, we describe a novel ubiquitin mark at the N-terminal tail of histone H2As consisting of two Lys residues at positions 13 and 15 (K13/K15). This "bidentate" site is a target of the DNA damage response (DDR) ubiquitin ligases RNF8 and RNF168. Histone mutants lacking the K13/K15 site impair RNF168- and DNA damage-dependent ubiquitination. Conversely, inactivation of the canonical C-terminal site prevents the constitutive monoubiquitination of histone H2As but does not abolish the ubiquitination induced by RNF168. A ubiquitination-defective mutant is obtained by inactivating both the N- and the C-terminal sites, suggesting that these are unique, non-redundant acceptors of ubiquitination on histone H2As. This unprecedented result implies that RNF168 generates a qualitatively different Ub mark on chromatin

Ribosome formation from subunits studied by stopped-flow and Rayleigh light scattering

Light scattering and standard stopped-flow techniques were used to monitor rapid association of ribosomal subunits during initiation of eubacterial protein synthesis. The effects of the initiation factors IF1, IF2, IF3 and buffer conditions on subunit association were studied along with the role of GTP in this process. The part of light scattering theory that is essential for kinetic measurements is high-lighted in the main text and a more general treatment of Rayleigh scattering from macromolecules is given in an appendix

Controlling R&D Projects: Framing a Process

The purpose of the following paper is to increase the control reliability for R&D projects developed in Tecnimont S.p.A.. The control process should provide accurate results to allow the realistic description of project progress, and it is more complex when dealing with R&D projects: the uncertainty for some activities complicates the process of assigning variances and, consequently, the schedule becomes less robust. The proposal of a control process came after a careful study of previous literature about project control. A strong emphasis was given to the planning phase: as the schedule serves as a reference for control, Goldratt’s Theory of Constraints – contaminated with elements from flexible methods and frameworks – is adopted to guarantee the baseline a stronger adherence to reality. The schedule higher adherence to reality was validated coupling the interview and the what-if methodology; these provided, respectively, a qualitative and quantitative proof of the effectiveness of the proposed control process. This control process appears to be reliant on a schedule that is more adherent to the events that can occur in reality. The higher accuracy of the schedule allows knowing more accurately which is the level of completeness of the project. By this means, it is sufficient to adopt a simple metric for project control instead of more complex algorithms (which are not always used in the industrial reality). Differently from some approaches such as stochastic and fuzzy logic, the control process is presented as a simple and pragmatic solution that can be adopted for R&D projects aimed at the development of industrial technology, including the construction of a pilot plant and the execution of experimental campaigns

A deep geoelectrical survey in the Southern Central Alps

A deep geoelectrical survey was carried out on the Southern Central AIps, to the north of Bergamo, by means of the continuous polar dipole-dipole electrode array. Among the 6 profiles executed, 4 revealed the existence of a substratum with very high resistivity values (15 000-40 000 ohm.m) and a flat not very deep upper boundary; its thickness exceeds the maximum expIoration depths of the soundings (1 to 6 km). On the grounds of general considerations and resistivity field data set, it is possible to infer that the high values should be ascribed to endogenous rather than to sedimentary rocks. A problem arises since these geophysical results are not in agreement with some geological models

Purification procedure for bacterial translational initiation factors IF2 and IF3.

In bacteria the initiation of protein synthesis is a complex phenomenon in which specific proteins, termed initiation factors (IFs) IF1, IF2, and IF3, are involved. Notwithstanding the progress made in understanding their functions, the precise molecular mechanisms of action of these factors remain somewhat obscure. One reason for this lack of knowledge is the difficulty involved in purifying sufficient quantities of these proteins. We have developed a new procedure for purification of IFs from recombinant Escherichia coli strains producing high levels of E. coli IF3 and Bacillus stearothermophilus IF2. This new procedure is quicker than previous methods, easily scaled up to large volumes, and can be used, with only minor modifications, for different IFs. This new purification method consists essentially of one chromatographic (FPLC) separation on an ion-exchange resin (S-Sepharose fast-flow or Mono-S HR). Using this procedure we have been able to obtain chromatographically pure and biologically active preparations of both IF2 and IF3

A deep geoelectrical survey in the Southern Central Alps

A deep geoelectrical survey was carried out on the Southern Central AIps, to the north of Bergamo, by means of the “continuous polar dipole-dipole” electrode array. Among the 6 profiles executed, 4 revealed the existence of a substratum with very high resistivity values (15 000-40 000 ohm.m) and a flat not very deep upper boundary; its thickness exceeds the maximum expIoration depths of the soundings (1 to 6 km). On the grounds of general considerations and resistivity field data set, it is possible to infer that the high values should be ascribed to endogenous rather than to sedimentary rocks. A problem arises since these geophysical results are not in agreement with some geological models