Neutron and X-ray diffraction studies on complex liquids

The above examples illustrate the extent to which present day neutron and X-ray diffraction methods are being used to determine interatomic structure in a wide range of liquid and amorphous systems. The determination of pair radial distribution functions not only offers a means to characterise different structures in liquids, but also provides theorists with information to construct realistic model potentials that can be used to calculate macroscopic behaviour and structural properties in regimes not currently accessible to experiment.\ud The well-established NDIS difference methods remain superior to all other methods for the determination of interatomic pairwise structure. The relatively new AXD (or DAS) difference methods have the potential to answer long-standing questions about the structure around species with mass number greater than about 30. However, the relatively low X-ray scattering power from light elements such as hydrogen, carbon, nitrogen etc. means that it will never be possible to resolve completely structures of biologically important liquids by X-ray methods alone. EXAFS spectroscopy has the distinct advantage over both diffraction techniques as it can be used to study local structure around particular species at high dilution. Therefore studies which combine reference data from AXD or NDIS, with extensive EXAFS data, are likely to be useful in studies of structure in regimes which prove difficult for AXD and NDIS. \ud It is clear that no one method will be sufficient to resolve structure at the required level of detail around all species in a complex liquid. Instead one must rely on a full complement of diffraction and other techniques including computer simulation to determine the complete atomic structure of a complex liquid or amorphous system.\ud On the technical front, the construction and commissioning of new neutron diffractometers with higher count rates, such as D20 and D4C at ILL, and GEM at ISIS with an optimised sample environment for work at non-ambient conditions, will enable new and more extensive research to be undertaken. Additionally, the new custom-built X-ray diffractometer for liquids proposed for the DIAMOND synchrotron being established at RAL will provide a much-needed boost for wide-ranging AXD and EXAFS investigations of complex liquids. \ud Besides the many studies of immediate interest suggested at the end of some sections, there are several investigations that will become feasible in the longer term as the technology develops. These include 1. the use of isotopes such as 12C and 13C and 33S and 32S which will enable detailed and extensive structural studies to be carried out on a wide range of biologically significant materials, and 2. the exploitation of higher neutron and X-ray count rates to facilitate real time experiments to investigate changes of structure as a chemical or biochemical reaction occurs. \ud The one strong theme which emerges from all the work described in this paper is that diffraction, especially that based on difference techniques, remains the best means to determine structure at atomic resolution in complex liquids

Assessing the selectivity and efficacy of dihydroquinolinone inhibitors directly targeting the oncogene LSF

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the second leading cause of cancer mortality. Despite the prevalence of HCC, there is only one FDA approved drug for the advanced disease, which extends lifespan by only 2-3 months and is associated with multiple side effects. Late SV40 Factor (LSF) has been shown to function as an oncogenic transcription factor in HCC, making it a promising protein target for HCC therapy. A library of dihydroquinolinones, termed FQIs, have been shown to inhibit LSF-DNA binding in in vitro and cellular assays. The lead compound FQI-1 causes dramatic mitotic defects in HCC cell lines, but has no or only limited growth effects on immortalized human hepatocytes or primary mouse hepatocytes. Additionally, FQI-1 has proven efficacious in in vivo HCC mouse models, with no evidence of associated toxicity. The dihydroquinolinones are promising compounds for a molecularly targeted therapy against HCC. Herein, the library of compounds was expanded and tested for potency in an aggressive HCC cell line, as well as for transactivation activity against the LSF and closely related family of transcription factors. Direct target engagement is shown for the first time with cellular thermal stability assays in HCC cell lysates. The lead compound is further shown to have a promising pharmacokinetic and tolerability profile in rats, supporting the development as a drug candidate. As a potential driver of mitosis, LSF may have a broader role in cancers beyond HCC. High-throughput screening identified hematopoietic cancer lineages as particularly sensitive to the dihydroquinolinones. As a proof-of-concept, the hematopoietic cell line U937 is shown to express high levels of LSF protein, and undergoes extensive apoptosis when treated with dihydroquinolinones or siRNA against the LSF subfamily.2019-11-03T00:00:00

Direct Experimental Evidence for Differing Reactivity Alterations of Minerals following Irradiation: The Case of Calcite and Quartz

Concrete, a mixture formed by mixing cement, water, and fine and coarse mineral aggregates is used in the construction of nuclear power plants (NPPs), e.g., to construct the reactor cavity concrete that encases the reactor pressure vessel, etc. In such environments, concrete may be exposed to radiation (e.g., neutrons) emanating from the reactor core. Until recently, concrete has been assumed relatively immune to radiation exposure. Direct evidence acquired on Ar$^+$-ion irradiated calcite and quartz indicates, on the contrary, that, such minerals, which constitute aggregates in concrete, may be significantly altered by irradiation. Specifically, while quartz undergoes disordering of its atomic structure resulting in a near complete lack of periodicity, i.e., similar to glassy silica, calcite only experiences random rotations, and distortions of its carbonate groups. As a result, irradiated quartz shows a reduction in density of around 15%, and an increase in chemical reactivity, described by its dissolution rate, similar to a glassy silica; i.e., an increase of around 3 orders of magnitude. Calcite however, shows little change in dissolution rates - although its density noted to reduce by around 9%. These differences are correlated with the nature of bonds in these minerals, i.e., being dominantly ionic or covalent, and the rigidity of the mineral's atomic network that is characterized by the number of topological constraints (n$_c$) that are imposed on the atoms in the network. The outcomes are discussed within the context of the durability of concrete structural elements formed with calcitic/quartzitic aggregates in nuclear power plants

Challenging drug target for Parkinson's disease: pathological complex of the chameleon TPPP/p25 and alpha-synuclein proteins

The hallmarks of Parkinson's disease and other synucleinopathies, Tubulin Polymerization Promoting Protein (TPPP/p25) and α-synuclein (SYN) have two key features: they are disordered and co-enriched/co-localized in brain inclusions. These Neomorphic Moonlighting Proteins display both physiological and pathological functions due to their interactions with distinct partners. To achieve the elective targeting of the pathological TPPP/p25-SYN but not the physiological TPPP/p25-tubulin complex, their interfaces were identified as a specific innovative strategy for the development of anti-Parkinson drugs. Therefore, the interactions of TPPP/p25 with tubulin and SYN were characterized which suggested the involvements of the 178–187 aa and 147–156 aa segments in the complexation of TPPP/p25 with tubulin and SYN, respectively. However, various truncated and deletion mutants reduced but did not abolish the interactions except one mutant; in addition synthetized fragments corresponding to the potential binding segments of TPPP/p25 failed to interact with SYN. In fact, the studies of the multiple interactions at molecular and cellular levels revealed the high conformational plasticity, chameleon feature, of TPPP/p25 that ensures exceptional functional resilience; the lack of previously identified binding segments could be replaced by other segments. The experimental results are underlined by distinct bioinformatics tools. All these data revealed that although targeting chameleon proteins is a challenging task, nevertheless, the validation of a drug target can be achieved by identifying the interface of complexes of the partner proteins existing at the given pathological conditions

Electromotive Force and Measurement in Several Systems

This book is devoted to different sides of Electromotive Force theory and its applications in Engineering science and Industry. The covered topics include the Quantum Theory of Thermoelectric Power (Seebeck Coefficient), Electromotive forces in solar energy and photocatalysis (photo electromotive forces), Electromotive Force in Electrochemical Modification of Mudstone, The EMF method with solid-state electrolyte in the thermodynamic investigation of ternary copper and silver chalcogenides, Electromotive Force Measurements and Thermodynamic Modelling of Electrolyte in Mixed Solvents, Application of Electromotive Force Measurement in Nuclear Systems Using Lead Alloys, Electromotive Force Measurements in High-Temperature Systems and finally, Resonance Analysis of Induced EMF on Coils

Mechanistic and Structural Insights into the Chemical Modulation of Amyloid Aggregation

The aggregation of amyloid-beta (Abeta) is implicated in the etiology of Alzheimer’s disease (AD). Aggregation in vivo permits interactions with transition metal ions and lipids of the cell membrane. Abeta-metal interactions are suggested to induce metal ion dyshomeostasis and promote oxidative stress while Abeta-membrane interactions catalyze the formation of specific oligomers which destabilize and permeabilize the lipid bilayer. Oxidative stress may also modulate bilayer integrity through acyl chain peroxidation which causes membrane thinning. The structural and mechanistic effects of these interactions on the aggregation of Abeta remain unclear. Multiple glycosidic polyphenol natural products and their esterified derivatives were investigated for their ability to function as molecular probes against metal-Abeta. The interactions between Abeta and thin model membranes were also investigated through a combination of NMR spectroscopy, fluorescence spectroscopy, and atomic force and transmission electron microscopies. The natural products Phlorizin, Verbascoside, and Rutin were all evaluated for their ability to modulate metal-Abeta aggregation. Verbascoside effectively inhibited aggregation while its esterified derivative, VPP, showed similar efficacy in vitro. Both compounds were also capable of disaggregating preformed fibrils, though they bound to both the monomeric and fibrillar forms of Abeta through distinct mechanisms. Esterification greatly reduced VPP’s ability to inhibit metal-Abeta cytotoxicity, however. Subsequently, the interaction and aggregation of Abeta with both thick (DOPC or POPC) and thin (DLPC) model membranes was evaluated. tr-NOESY and relaxation based NMR experiments probed monomer interaction on the bilayer surface; folding was conserved regardless of bilayer thickness, suggesting that the preliminary interaction is exclusively driven by surface contacts. Additionally, the work provides the first experimentally derived structural constraints for membrane-associated Abeta. The progression of Abeta from its conserved, folded, monomeric state to its aggregated state was monitored in the presence of thick and thin membranes. DLPC bilayers uniquely stabilized membrane associated oligomers while simultaneously destabilizing the bilayer. DLPC also remodeled preformed fibrils into a pseudo-unfolded state which resembles protofibrillar aggregates. These results provide a new reagent with potential applications as a probe against metal-Abeta in vitro and insights into early structures of membrane-associated Abeta and mechanisms by which membrane structure can modulate the Abeta aggregation.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/135884/1/kkorshav_1.pd

FUNCTIONAL CHARACTERIZATION OF TOMATO PROSYSTEMIN AND PROSYSTEMIN REGIONS: NOVEL TOOLS FOR PLANT DEFENSE

Prosystemin (ProSys) is a pro-hormone of 200 aminoacidic residues which releases a bioactive peptide hormone of 18 amino acids called Systemin (Sys) involved in the activation of a complex signaling cascade that leads to the production of defense compounds. The tomato genome contains only one copy of Prosys gene; it is composed of 4176 bp and is structured into 11 exons, of which the last one codes for Sys. Sys peptide was traditionally considered as the principal actor that confers protection against both biotic and abiotic environmental challenges observed in tomato plant overexpressing the ProSys. Thus, a single peptide hormone is capable of eliciting multiple defense pathways to counteract a wide range of unfavourable conditions for the plant. So far, it was unknown whether ProSys had any biological function other than being an intermediate in the synthesis of Sys. However, recent evidences suggest that Prosys devoid of the Sys sequence contributes to defense responses. This observation prompted us to investigate the biochemical and structural features of the ProSys protein. To this purpose ProSys has been expressed in BL21 (DE3) E. coli cells and purified. A detailed characterization of this pro-hormone by means of multidisciplinary approach revealed for the first time that this precursor behaves like an intrinsically disordered protein (IDP) possessing intrinsically disordered regions (IDRs) within the sequence. However, to find out an alternative delivery strategy not relying on transgenic plants, we decided to investigate the effects of exogenous application of the recombinant pro-hormone on the defense responses and its potential use as a plant protection tool in tomato. In particular, plant assays revealed that ProSys direct treatment of leaves is biologically active being very effective in the induction, both locally and systemically, of tomato defense-related genes, conferring protection against different pests. To our knowledge, this is the first biotic stress related IDP identified in plants, suggesting new interesting insights on the role of IDPs. into plant response against biotic stressors. IDPs are functionally important proteins lacking a stable or ordered three-dimensional structure. Despite being highly flexible, it has been demonstrated that IDPs have crucial roles in signal transduction process, cell-cycle regulation, gene expression and molecular recognition. The role of IDPs in these processes has been systematically studied in the animal kingdom. In contrast, less reports of these proteins from the plant kingdom are available in the scientific literature. In plant biology, IDPs play crucial roles among plant stress responses, signaling, and molecular recognition pathways, that resemble the functional roles of ProSys in the tomato defense pathways activated upon several biotic and abiotic stresses. These evidences aimed our study focused on the establishment of a relationship between ProSys structure and its biological activity. To this purpose different regions of ProSys have been expressed in BL21 (DE3) E. coli cells, purified and then characterized by a biophysical and biochemical point of view. Results showed that the recombinant fragments are disordered in agreement with what previously shown for the whole precursor. It was subsequently investigated whether the recombinant ProSys Fragments had any biological activity in activating defense responses upon biotic or abiotic attacks. In particular, by using a combination of gene expression analysis and bioassays, we proved that the exogenous supply of the recombinant ProSys Fragments to tomato plants promotes early and late plant defense genes, but only two fragments (namely Fragment I and III, encompassing the N-terminal part of the protein) were found to be the most promising. In addition, it was observed that the latter ones counteracted the development of Spodoptera littoralis larvae and the fungal leaf colonization. These results suggest that the direct application of these recombinant products, which are safe to humans and no-target organisms, may represent an exploitable tool for crop protection

Corrosion Performance of Additively Manufactured Alloys and Hot Corrosion

Additive manufacturing (AM) has gained attention in recent years due to its unique properties in the fabrication of complex parts. Same as any other new topics, in some areas, there is still a lack of enough knowledge and there is the need for further investigations to enable the applications of AM parts widely in industries. ‎Chapter 2, and ‎Chapter 5 to ‎Chapter 8 of this report are focused on the corrosion properties of the parts and coatings fabricated using the laser powder bed fusion based AM method or laser surface processing method, including a comprehensive review. Laser powder bed fusion based AM was used to prepare copper alloy, titanium alloy, and stainless steel AM parts, and laser surface modification was performed on Fe-14Cr alloy. The application of nickel superalloys is well known in various industries. ‎Chapter 3, ‎Chapter 9, ‎Chapter 10 are a part of a DOE-funded project which has the final goal of producing Inconel 939 based superalloy parts with additive manufacturing method. The first step was to modify its composition to reach a better fatigue behavior (‎Chapter 9) with the help of phase composition and antiphase boundary energy associated with each phase. Since the lack of information about the hot corrosion properties of the newly designed alloys, the last chapter has been dedicated to evaluating Inconel 939 corrosion performance at elevated temperatures