Effects of Initial Surface Evaporation on the Performance of Fly Ash-Based Geopolymer Paste at Elevated Temperatures

Geopolymer concrete is a valuable and alternative type of concrete that is free of traditional cement. Generally, geopolymer concretes require a source material, which is rich in silicon and aluminum. Furthermore, fly ash-based geopolymer concretes have been proven to have superior fire resistance, primarily due to their ceramic properties, and are inherently environmentally-friendly given their zero-cement content. This paper presents the effects on initial evaporation on the performance of fly ash-based geopolymer pastes after exposure to elevated temperatures of 400 °C and 800 °C. The fly ash (FA) samples used in the present study included: Gladstone and Gladstone/Callide. The results for sealed samples placed in the oven during curing were much more consistent than the samples that were not kept covered. In addition, Gladstone fly ash-based geopolymer samples that were sealed recorded an initial maximum compressive strength reading of ca. 75 MPa, while sealed Gladstone/Callide fly ash-based geopolymer samples, of the same mix design, only recorded an initial maximum compressive strength reading of ca. 50 MPa (both subjected to oven curing at 60 °C for 24 h). However, Gladstone/Callide fly ash-based geopolymer samples exhibited a significant strength gain, ca. 90 MPa, even after being subjected to 400 °C.

Gas-stabilizing nanoparticles for ultrasound imaging and therapy of cancer

The use of ultrasound in the clinic has been long established for cancer detection and image-guided tissue biopsies. In addition, ultrasound-based methods have been widely explored to develop more effective cancer therapies such as localized drug delivery, sonodynamic therapy, and focused ultrasound surgery. Stabilized fluorocarbon microbubbles have been in use as contrast agents for ultrasound imaging in the clinic for several decades. It is also known that microbubble cavitation could generate thermal, mechanical, and chemical effects in the tissue to improve ultrasound-based therapies. However, the large size, poor stability, and short-term cavitation activity of microbubbles limit their applications in cancer imaging and therapy. This review will focus on an alternative type of ultrasound responsive material; gas-stabilizing nanoparticles, which can address the limitations of microbubbles with their nanoscale size, robustness, and high cavitation activity. This review will be of interest to researchers who wish to explore new agents to develop improved methods for molecular ultrasound imaging and therapy of cancer.

Cycloalkane-modified amphiphilic polymers provide direct extraction of membrane proteins for CryoEM analysis

Membrane proteins are essential for cellular growth, signalling and homeostasis, making up a large proportion of therapeutic targets. However, the necessity for a solubilising agent to extract them from the membrane creates challenges in their structural and functional study. Although amphipols have been very effective for single-particle electron cryo-microscopy (cryoEM) and mass spectrometry, they rely on initial detergent extraction before exchange into the amphipol environment. Therefore, circumventing this pre-requirement would be a big advantage. Here we use an alternative type of amphipol: a cycloalkane-modified amphiphile polymer (CyclAPol) to extract Escherichia coli AcrB directly from the membrane and demonstrate that the protein can be isolated in a one-step purification with the resultant cryoEM structure achieving 3.2 Å resolution. Together this work shows that cycloalkane amphipols provide a powerful approach for the study of membrane proteins, allowing native extraction and high-resolution structure determination by cryoEM.

Features of feeding the slaughter young stock of minks with complete feed

In the domestic fur farming there is an urgent need to introduce an alternative type of feeding for young minks. The purpose of the work is to study possible of feeding commercial young minks with complete feed, consisting of animal and plant components. Methods. In a scientific and economic experiment on young sapphire minks intended for slaughter, 2 groups were formed according to the principle of analogues, 32 heads each (16 males and 16 females): I – control, II – experimental. The animals of the control group received from 2015 August 5 to September 15 a typical general economic ration in the form of a wet mash, an experimental one – a loose, complete feed (made according to a recipe developed by us, taking into account the current norms), mixed with water in a ratio of 1:2. All experimental studies were carried out using classical zootechnical, pathomorphological, histological, veterinary-sanitary and statistical methods. Results and scope. The dynamics of the live weight of the experimental minks showed that by the beginning of the main period, the males and females of the experimental group lagged behind the control animals, after switching to the main diet for slaughter, the males lag remained and the females caught up with the control animals. But the control and experimental animals did not differ in the length of the carcass. The safety of the livestock was higher in the experimental group: males – 100 %, females – 93.75 %; in control – 93.75 % and 87.5 %, respectively. According to the main productive indicator – the quality test – the skins of the control and experimental animals did not have significant differences. Thus, the development of an alternative type of feeding is quite possible, but it requires improvement in the direction of increasing the coefficient of digestibility of nutrients and adaptation of males to an uncharacteristic type of feeding. Scientific novelty. The prospects and the need to introduce an alternative type of feeding the commercial young stock of minks with full-feed compound feeds into the domestic fur farming are outlined.

Uncovering the distinct properties of a bacterial type I-E CRISPR activation system

ABSTRACTSynthetic gene regulators based upon CRISPR-Cas systems offer highly programmable technologies to control gene expression in bacteria. Bacterial CRISPR activators (CRISPRa) have been developed that use engineered type II CRISPR-dCas9 to localize transcription activation domains near promoter elements to activate transcription. However, several reports have demonstrated distance-dependent requirements and periodical activation patterns that overall limit the flexibility of these systems. Here, we demonstrate the potential of using an alternative type I-E CRISPR-Cas system to create a CRISPRa with distinct and expanded regulatory properties. We create the first bacterial CRISPRa system based upon a type I-E CRISPR-Cas, and demonstrate differences in the activation range of this system compared to type II CRISPRa systems. Furthermore, we characterize the distance-dependent activation patterns of type I-E CRISPRa to reveal a distinct and more frequent periodicity of activation.

Fractional optimal control of COVID-19 pandemic model with generalized Mittag-Leffler function

In this paper, we consider a fractional COVID-19 epidemic model with a convex incidence rate. The Atangana–Baleanu fractional operator in the Caputo sense is taken into account. We establish the equilibrium points, basic reproduction number, and local stability at both the equilibrium points. The existence and uniqueness of the solution are proved by using Banach and Leray–Schauder alternative type theorems. For the fractional numerical simulations, we use the Toufik–Atangana scheme. Optimal control analysis is carried out to minimize the infection and maximize the susceptible people.

The Effects of Pro-Social and Pro-Environmental Orientation on Crowdfunding Performance

Reward-based crowdfunding is an alternative type of project financing in which a large and dispersed online crowd contributes relatively small financial amounts in exchange for innovative products or services. The crowd is driven by a broad set of motivations that also comprises sustainability awareness. However, empirical research on crowdfunding projects that feature social or environmental considerations provides inconclusive results. In our study, we enhance the understanding of whether a pro-social and pro-environmental orientation affects the performance of reward-based crowdfunding. We draw on the literature stream of social movements to explain how linguistic framing mobilizes individuals and relate this to how selection is enabled and action is guided in a crowdfunding setting. Based on a sample of 1049 projects from Kickstarter, we employ computer-aided text analysis (CATA) to capture the pro-social and pro-environmental orientation of the project descriptions and transcribed video pitches as linguistic constructs. We found that the level of pro-social or pro-environmental orientation has an inverted U-shaped effect on crowdfunding performance. Moreover, this relationship differs when crowdfunding projects feature a creative product or service idea. Our results suggest that entrepreneurs need to delicately balance a pro-social or pro-environmental orientation and find the “right” level of emphasis to create a competitive advantage.

Structure and nature of ice XIX

Ice is a material of fundamental importance for a wide range of scientific disciplines including physics, chemistry, and biology, as well as space and materials science. A well-known feature of its phase diagram is that high-temperature phases of ice with orientational disorder of the hydrogen-bonded water molecules undergo phase transitions to their ordered counterparts upon cooling. Here, we present an example where this trend is broken. Instead, hydrochloric-acid-doped ice VI undergoes an alternative type of phase transition upon cooling at high pressure as the orientationally disordered ice remains disordered but undergoes structural distortions. As seen with in-situ neutron diffraction, the resulting phase of ice, ice XIX, forms through a Pbcn-type distortion which includes the tilting and squishing of hexameric clusters. This type of phase transition may provide an explanation for previously observed ferroelectric signatures in dielectric spectroscopy of ice VI and could be relevant for other icy materials.

Physiological relevance, localization and substrate specificity of the alternative (type II) mitochondrial NADH dehydrogenases of Ogataea parapolymorpha

Mitochondria from Ogataea parapolymorpha harbor a branched electron-transport chain containing a proton-pumping Complex I NADH dehydrogenase and three alternative (type II) NADH dehydrogenases (NDH2s). To investigate the physiological role, localization and substrate specificity of these enzymes, growth of various NADH dehydrogenase mutants was quantitatively characterized in shake-flask and chemostat cultures, followed by oxygen-uptake experiments with isolated mitochondria. Furthermore, NAD(P)H:quinone oxidoreduction of the three NDH2s were individually assessed. Our findings show that the O. parapolymorpha respiratory chain contains an internal NADH-accepting NDH2 (Ndh2-1/OpNdi1), at least one external NAD(P)H-accepting enzyme and likely additional mechanisms for respiration-linked oxidation of cytosolic NADH. Metabolic regulation appears to prevent competition between OpNdi1 and Complex I for mitochondrial NADH. With the exception of OpNdi1, the respiratory chain of O. parapolymorpha exhibits metabolic redundancy and tolerates deletion of multiple NADH-dehydrogenase genes without compromising fully respiratory metabolism.ImportanceTo achieve high productivity and yields in microbial bioprocesses, efficient use of the energy substrate is essential. Organisms with branched respiratory chains can respire via the energy-efficient proton-pumping Complex I, or make use of alternative NADH dehydrogenases (NDH2s). The yeast Ogataea parapolymorpha contains three uncharacterized, putative NDH2s which were investigated in this work. We show that O. parapolymorpha contains at least one ‘internal’ NDH2, which provides an alternative to Complex I for mitochondrial NADH oxidation, albeit at a lower efficiency. The use of this NDH2 appeared to be limited to carbon excess conditions and the O. parapolymorpha respiratory chain tolerated multiple deletions without compromising respiratory metabolism, highlighting opportunities for metabolic (redox) engineering. By providing a more comprehensive understanding of the physiological role of NDH2s, including insights into their metabolic capacity, orientation and substrate specificity this study also extends our fundamental understanding of respiration in organisms with branched respiratory chains.