Hydrogen Production in the Cyanobacterium Synechocystis sp. PCC 6803 with Engineered Subunit of the Bidirectional H2-ase

Hydrogenase (H2-ase) enzyme holds great promise as a bio-generator for bio-solar hydrogen (H2) production. Consequently, an oxygen-tolerant H2-ase is needed in a photosynthetic organism.  In this work, a mutant strain of Synechocystis sp. PCC 6803 with modified H2-ase analyzed under various physiological conditions. The growth rate was higher than that of wt strain and cellular capacity to fix carbon was increased, as shown by higher glycogen accumulation. Oxygen evolution by mutant strain in chemostats was higher than by wt cells over a range of pH levels. The mutant displayed significantly higher hydrogen (H2) production than wt cells, especially at high pH. Examinations of electron flow pathways in the presence of various inhibitors indicated that the genetically modified H2-ase apparently behaves similarly to the wt with respect to its electron source. Remarkably, it was consistently observed H2 production under continuous light conditions, in the presence of oxygen (O2), under many circumstances in both chemostat and batch tests. H2 production in the light was improved under alkaline pH in mutant strain than wt. The data suggest that the genetically modified hydrogenase (H2ase) is a functionally active. Several lines of evidence suggest that O2 may be important in draining electrons from the donor side of photosystem I (PSI) in turn increases the linear electron flow and thereby helping to feed the H2ase activity. In conclusion, the bidirectional H2ase in Synechocystis may play a critical role in cell physiology not only under anoxic conditions but also under O2-evolving activity. Keywords: Cyanobacteria, Hydrogen, Hydrogenase, Protein engineering

Application of Topology Optimisation to Steel Node-Connections and Additive Manufacturing

Structural Topology Optimisation (STO) is a prevalent optimisation technique used nowadays to reach desired weight-to-stiffness ratios via highly complex and efficient designs unable to achieve otherwise. Additive manufacturing (AM) is widely known in the manufacturing industry and provides designers with a higher degree of freedom in realising highly optimised designs through a layer-based fabrication process. This paper focuses on reticulated structures and proposes using STO and AM to design and fabricate alternative connection designs with outstanding bespoke performance and drastically reduced weight. It studies the optimisation of a conventional node-connection found in reticulated timber structures under four loading cases, to producing state-of-the-art optimised connection designs, each capable of withstanding one of the four selected loading cases. The results are compared with the conventional node-connection, and the optimised configurations achieved up to 46.9% weight reduction. A selection of the highly bespoke scaled-down designs was additively manufactured in two different materials (metallic and polymer) as a proof of concept for the capacity of the technologies available for future testing

Covariant gauge-invariant perturbations in multifluid f(R) gravity

We study the evolution of scalar cosmological perturbations in the (1+3)- covariant gauge-invariant formalism for generic $f(R)$ theories of gravity. Extending previous works, we give a complete set of equations describing the evolution of matter and curvature fluctuations for a multi-fluid cosmological medium. We then specialize to a radiation-dust fluid described by barotropic equations of state and solve the perturbation equations around a background solution of $R^{n}$ gravity. In particular we study exact solutions for scales much smaller and much larger than the Hubble radius and show that $n>2/3$ in order to have a growth rate compatible with the M\'esz\'aros effect.Comment: 32 pages, 3 figures, published versio

EnHMM: On the Use of Ensemble HMMs and Stack Traces to Predict the Reassignment of Bug Report Fields

Bug reports (BR) contain vital information that can help triaging teams prioritize and assign bugs to developers who will provide the fixes. However, studies have shown that BR fields often contain incorrect information that need to be reassigned, which delays the bug fixing process. There exist approaches for predicting whether a BR field should be reassigned or not. These studies use mainly BR descriptions and traditional machine learning algorithms (SVM, KNN, etc.). As such, they do not fully benefit from the sequential order of information in BR data, such as function call sequences in BR stack traces, which may be valuable for improving the prediction accuracy. In this paper, we propose a novel approach, called EnHMM, for predicting the reassignment of BR fields using ensemble Hidden Markov Models (HMMs), trained on stack traces. EnHMM leverages the natural ability of HMMs to represent sequential data to model the temporal order of function calls in BR stack traces. When applied to Eclipse and Gnome BR repositories, EnHMM achieves an average precision, recall, and F-measure of 54%, 76%, and 60% on Eclipse dataset and 41%, 69%, and 51% on Gnome dataset. We also found that EnHMM improves over the best single HMM by 36% for Eclipse and 76% for Gnome. Finally, when comparing EnHMM to Im.ML.KNN, a recent approach in the field, we found that the average F-measure score of EnHMM improves the average F-measure of Im.ML.KNN by 6.80% and improves the average recall of Im.ML.KNN by 36.09%. However, the average precision of EnHMM is lower than that of Im.ML.KNN (53.93% as opposed to 56.71%).Comment: Published in Proceedings of the 28th IEEE International Conference on Software Analysis, Evolution and Reengineering (SANER 2021), 11 pages, 7 figure

Effects of Acute or Chronic Ethanol Exposure during Adolescence on Behavioral Inhibition and Efficiency in a Modified Water Maze Task

Ethanol is well known to adversely affect frontal executive functioning, which continues to develop throughout adolescence and into young adulthood. This is also a developmental window in which ethanol is misused by a significant number of adolescents. We examined the effects of acute and chronic ethanol exposure during adolescence on behavioral inhibition and efficiency using a modified water maze task. During acquisition, rats were trained to find a stable visible platform onto which they could escape. During the test phase, the stable platform was converted to a visible floating platform (providing no escape) and a new hidden platform was added in the opposite quadrant. The hidden platform was the only means of escape during the test phase. In experiment 1, adolescent animals received ethanol (1.0g/kg) 30min before each session during the test phase. In experiment 2, adolescent animals received chronic intermittent ethanol (5.0g/kg) for 16 days (PND30 To PND46) prior to any training in the maze. At PND72, training was initiated in the same modified water maze task. Results from experiment 1 indicated that acute ethanol promoted behavioral disinhibition and inefficiency. Experiment 2 showed that chronic intermittent ethanol during adolescence appeared to have no lasting effect on behavioral disinhibition or new spatial learning during adulthood. However, chronic ethanol did promote behavioral inefficiency. In summary, results indicate that ethanol-induced promotion of perseverative behavior may contribute to the many adverse behavioral sequelae of alcohol intoxication in adolescents and young adults. Moreover, the long-term effect of adolescent chronic ethanol exposure on behavioral efficiency is similar to that observed after chronic exposure in humans

Protein kinase Cζ regulates phospholipase D activity in rat-1 fibroblasts expressing the α(1A )adrenergic receptor

BACKGROUND: Phenylephrine (PHE), an α(1 )adrenergic receptor agonist, increases phospholipase D (PLD) activity, independent of classical and novel protein kinase C (PKC) isoforms, in rat-1 fibroblasts expressing α(1A )adrenergic receptors. The aim of this study was to determine the contribution of atypical PKCζ to PLD activation in response to PHE in these cells. RESULTS: PHE stimulated a PLD activity as demonstrated by phosphatidylethanol production. PHE increased PKCζ translocation to the particulate cell fraction in parallel with a time-dependent decrease in its activity. PKCζ activity was reduced at 2 and 5 min and returned to a sub-basal level within 10–15 min. Ectopic expression of kinase-dead PKCζ, but not constitutively active PKCζ, potentiated PLD activation elicited by PHE. A cell-permeable pseudosubstrate inhibitor of PKCζ reduced basal PKCζ activity and abolished PHE-induced PLD activation. CONCLUSION: α(1A )adrenergic receptor stimulation promotes the activation of a PLD activity by a mechanism dependent on PKCζ; Our data also suggest that catalytic activation of PKCζ is not required for PLD stimulation

РОЛЬ EZH2 И ARID1A В ДИАГНОСТИКЕ ПЛОСКИХ УРОТЕЛИАЛЬНЫХ ОПУХОЛЕЙ С АТИПИЕЙ

Background. Diagnosis of urothelial carcinoma in situ is of great importance because it has prognostic and therapeutic value.We aim to determine the utility of EZH2 and ARID1A as a new tool in the diagnosis of carcinoma in situ.Material and Methods. This retrospective cross-sectional study included Twenty-four specimens of flat urothelial lesions, twenty specimens of CIS, and 10 of normal adjacent urothelium that was taken by cystoscopic resection biopsy procedure. immunohistochemical expression of EZH2 and ARID1A. were evaluated in all studied cases.Results. All normal urothelium specimens showed high nuclear staining for ARID1A and negative nuclear staining for EZH2. High EZH2 expression was observed in 80 % of CIS specimens compared to 20 % of flat urothelial lesions with atypia (p=0.001 ), while high ARID1A expression was observed in 70.8 % of flat urothelial lesions with atypia compared to 25 % of CIS specimens (p=0.001). EZH2 was more accurate and specific in the diagnosis of carcinoma in situ.Conclusion. EZH2 and ARID1A are promising diagnostic markers for urothelial CIS. EZH2 is more accurate and specific than ARID1A in the diagnosis of carcinoma in situ versus other flat urothelial lesions. Актуальность. Диагностика уротелиальной карциномы in situ имеет большое значение, поскольку обладает прогностической и терапевтической ценностью.Целью исследования было определить роль EZH2 и ARID1A в диагностике карциномы in situ.Материал и методы. Ретроспективное перекрестное исследование включало 24 образца плоских уротелиальных опухолей, 20 образцов CIS и 10 образцов нормального прилегающего уротелия, взятых при цистоскопической биопсии. Во всех случаях была оценена иммуногистохимическая экспрессия EZH2 и ARID1A.Результаты. Все образцы нормального уротелия показали высокое ядерное окрашивание на ARID1A и отрицательное ядерное окрашивание на EZH2. Высокая экспрессия EZH2 наблюдалась в 80 % образцов CIS по сравнению с 20 % плоских уротелиальных опухолей с атипией (p=0,001), в то время как высокая экспрессия ARID1A наблюдалась в 70,8 % плоских уротелиальных опухолей с атипией по сравнению с 25 % образцов CIS (р=0,001). EZH2 был более точным и специфичным при диагностике карциномы in situ.Заключение. EZH2 и ARID1A являются перспективными диагностическими маркерами уротелиальной карциномы in situ. EZH2 более точен и специфичен, чем ARID1A, в диагностике карциномы in situ по сравнению с другими плоскими уротелиальными опухолями.

Cosmological dynamics of fourth order gravity: A compact view

We construct a compact phase space for flat FLRW spacetimes with standard matter described by a perfect fluid with a barotropic equation of state for general f(R) theories of gravity, subject to certain conditions on the function f. We then use this framework to study the behaviour of the phase space of Universes with a non-negative Ricci scalar in R + {\alpha}R^n gravity. We find a number of interesting cosmological evolutions which include the possibility of an initial unstable power-law inflationary point, followed by a curvature fluid dominated phase mimicking standard radiation, then passing through a standard matter (CDM) era and ultimately evolving asymptotically towards a de-Sitter-like late-time accelerated phase.Comment: 8 pages, 3 figures, revtex4-