Titanium (IV) Oxide Nanotubes in Design of Active SERS Substrates for High Sensitivity Analytical Applications: Effect of Geometrical Factors in Nanotubes and in Ag-n Deposits

In this chapter, we summarize the results of recent investigations into TiO2 nanotubular oxide layers on Ti metal loaded with Ag nanoparticles, which act as efficient surface plasmon resonators. These Ag-n/TiO2 NT/Ti composite layers appear to be useful as platforms for precise surface analytical investigations of minute amounts of numerous types of organic molecules: pyridine (Py), mercaptobenzoic acid (MBA), 5-(4-dimethylaminobenzylidene) rhodamine (DBRh) and rhodamine (R6G); such investigations are known as surface enhanced Raman Spectroscopy (SERS). Geometrical factors related to the nanotubes and the silver deposit affect the SERS activity of the resulting composite layers. The results presented here show that, for a carefully controlled amount of Ag-n deposit located mainly on the tops of titania nanotubes, it is possible to obtain high-quality, reproducible SERS spectra for probe molecules at an enhancement factor of 105–106. This achievement makes it possible to detect organic molecules at concentrations as low as, e.g., 10−9 M for R6G molecules. SEM investigations suggest that the size of the nanotubes, and both the lateral and perpendicular distribution of Ag-n (on the tube tops and walls), are responsible for the SERS activity. These features of the Ag-n/TiO2 NT/Ti composite layer provide a variety of cavities and slits which function as suitable resonators for the adsorbed molecules

Microstructure and defect analysis in the vicinity of blisters in polycrystalline tungsten

AbstractUp to now, analyzing the production of dislocation-type defects in the subsurface region of plasma or ion-exposed tungsten samples has been hampered by the challenging production of suitable cross-section samples for transmission electron microscopy. We present two reliable methods based on precision electropolishing to prepare cross-sections of tungsten that allow direct imaging of dislocation-type defects by scanning as well as by transmission electron microscopy. Using these methods, we are able to demonstrate a clear enhancement of the dislocation density in the caps of blisters on tungsten exposed to H isotope plasma, i.e., of surface morphologies that are correlated to subsurface cavities. As a benchmark, we also show a cross-section of tungsten irradiated by 20 MeV W6+ ions

Quasi-static and dynamic compressive behaviorof Gum Metal: experiment and constitutive model

The quasi-static and high strain rate compressive behavior of Gum Metal with composition Ti-36Nb-Ta-3Zr-0.3O (wt pct) has been investigated using an electromechanical testing machine and a split Hopkinson pressure bar, respectively. The stress–strain curves obtained for Gum Metal tested under monotonic and dynamic loadings revealed a strain-softening effect which intensified with increasing strain rate. Moreover, the plastic flow stress was observed to increase for both static and dynamic loading conditions with increasing strain rate. The microstructural characterization of the tested Gum Metal specimens showed particular deformation mechanisms regulating the phenomena of strain hardening and strain softening, namely an adiabatic shear band formed at ~ 45 deg with respect to the loading direction as well as widely spaced deformation bands (kink bands). Dislocations within the channels intersecting with twins may cause strain hardening while recrystallized grains and kink bands with crystal rotation inside the grains may lead to strain softening. A constitutive description of the compressive behavior of Gum Metal was proposed using a modified Johnson-Cook model. Good agreement between the experimental and the numerical data obtained in the work was achieved

PROPERTIES OF DIAMOND-LIKE CARBON COATINGS DEPOSITED ON CoCrMo ALLOYS

This paper presents results of the structure analysis and tribological testing of a-C:H type diamond-like carbon (DLC) coatings produced by the Plasma Assisted Chemical Vapour Deposition (PACVD) technology on CoCrMo specimens. The DLC coating structure was studied by observing the surface topography using a scanning electron microscope (SEM) in the SE and STEM modes and a profilometer. Raman spectroscopy provided information on hybridized covalent bonds. The structural analysis involved observing the cross-sections of the coatings using a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) to determine the concentration and distribution of the constituent elements in the coating. Wear resistance was studied by applying a T-17 pin-on-plate tribological system: a polymeric pin made of ultra-high-molecular-weight polyethylene (UHMWPE) and a CoCrMo plate with a DLC coating. The testing was conducted under friction conditions using Ringer’s solution as a lubricant. The test results showed that the application of DLC coatings definitely improves the serviceability of a surface

The taxonomy and diversity of Proschkinia (Bacillariophyta), a common but enigmatic genus from marine coasts

Detailed morphological documentation is provided for established Proschkinia taxa, including the generitype, P. bulnheimii, and P. complanata, P. complanatula, P. complanatoides and P. hyalosirella, and six new species. All established taxa are characterized from original material from historical collections. The new species described in this paper (P. luticola, P. staurospeciosa, P. impar, P. modesta, P. fistulispectabilis, and P. rosowskii) were isolated from the Western Pacific (Yellow Sea coast of Korea) and the Atlantic (Scottish and Texas coasts). Thorough documentation of the frustule, valve and protoplast architecture revealed the combination of characters diagnostic of the genus Proschkinia: a single‐lobed chloroplast; a broad girdle composed of U‐shaped, perforated bands; the position of the conopeate raphe‐sternum relative to the external and internal valve surface; and the presence of an occluded process through the valve, termed the “fistula”. Seven strains of Proschkinia were grown in culture and five of these were sequenced for nuclear ribosomal SSU and plastid‐encoded rbcL. Phylogenetic analysis recovered a clade of Proschkinia with Fistulifera, another fistula‐bearing diatom genus, and together these were sister to a clade formed of the Stauroneidaceae; in turn, all of these were sister to a clade composed of Parlibellus and two monoraphid genera Astartiella and Schizostauron. Despite morphological similarities between Proschkinia and the Naviculaceae, these two taxa are distant in our analysis. We document the variation in the morphology of Proschkinia, including significant variability in the fistula, suggesting that fistula ultrastructure might be one of the key features for species identification within the genus.info:eu-repo/semantics/acceptedVersio

Dissecting the RecA-(In)dependent Response to Mitomycin C in Mycobacterium tuberculosis Using Transcriptional Profiling and Proteomics Analyses

Institutional Review Board Statement: The experimental procedures were approved and conducted according to guidelines of the appropriate Polish Local Ethics Commission for Experiments on Animals No. 9 in Lodz (Agreement 9/ŁB87/2018). Acknowledgments: We thank Jeremy Rock and Sarah Fortune for providing us with the pLJR965 vector and detailed instructions for the generation of Cas9-regulated strains in M. tuberculosis. The authors thank the mass spectrometry service at the Institute of Biochemistry and Biophysics PAS in Warsaw for MS analysis. The MS analysis equipment used for the analysis was sponsored in part by the Centre for Preclinical Research and Technology (CePT), a project cosponsored by the European Regional Development Fund and Innovative Economy, the National Cohesion Strategy of Poland.Mycobacteria exploit at least two independent global systems in response to DNA damage: the LexA/RecA-dependent SOS response and the PafBC-regulated pathway. Intracellular pathogens, such as Mycobacterium tuberculosis, are exposed to oxidative and nitrosative stress during the course of infection while residing inside host macrophages. The current understanding of RecA-independent responses to DNA damage is based on the saprophytic model of Mycobacterium smegmatis, a free-living and nonpathogenic mycobacterium. The aim of the present study was to identify elements of RecA-independent responses to DNA damage in pathogenic intracellular mycobacteria. With the help of global transcriptional profiling, we were able to dissect RecA-dependent and RecA-independent pathways. We profiled the DNA damage responses of an M. tuberculosis strain lacking the recA gene, a strain with an undetectable level of the PafBC regulatory system, and a strain with both systems tuned down simultaneously. RNA-Seq profiling was correlated with the evaluation of cell survival in response to DNA damage to estimate the relevance of each system to the overall sensitivity to genotoxic agents. We also carried out whole-cell proteomics analysis of the M. tuberculosis strains in response to mitomycin C. This approach highlighted that LexA, a well-defined key element of the SOS system, is proteolytically inactivated during RecA-dependent DNA repair, which we found to be transcriptionally repressed in response to DNA-damaging agents in the absence of RecA. Proteomics profiling revealed that AlkB was significantly overproduced in the ΔrecA pafBCCRISPRi/dCas9 strain and that Holliday junction resolvase RuvX was a DNA damage response factor that was significantly upregulated regardless of the presence of functional RecA and PafBC systems, thus falling into a third category of DNA damage factors: RecA- and PafBC-independent. While invisible to the mass spectrometer, the genes encoding alkA, dnaB, and dnaE2 were significantly overexpressed in the ΔrecA pafBCCRISPRi/dCas9 strain at the transcript level.A.B. was supported by grant “OPUS” from the National Science Centre, Poland, UMO2015/19/B/NZ6/02978. P.P. was supported by grant “OPUS” from the National Science Centre, Poland, UMO-2019/33/B/NZ1/02770

Repriming DNA synthesis: an intrinsic restart pathway that maintains efficient genome replication

To bypass a diverse range of fork stalling impediments encountered during genome replication, cells possess a variety of DNA damage tolerance (DDT) mechanisms including translesion synthesis, template switching, and fork reversal. These pathways function to bypass obstacles and allow efficient DNA synthesis to be maintained. In addition, lagging strand obstacles can also be circumvented by downstream priming during Okazaki fragment generation, leaving gaps to be filled post-replication. Whether repriming occurs on the leading strand has been intensely debated over the past half-century. Early studies indicated that both DNA strands were synthesised discontinuously. Although later studies suggested that leading strand synthesis was continuous, leading to the preferred semi-discontinuous replication model. However, more recently it has been established that replicative primases can perform leading strand repriming in prokaryotes. An analogous fork restart mechanism has also been identified in most eukaryotes, which possess a specialist primase called PrimPol that conducts repriming downstream of stalling lesions and structures. PrimPol also plays a more general role in maintaining efficient fork progression. Here, we review and discuss the historical evidence and recent discoveries that substantiate repriming as an intrinsic replication restart pathway for maintaining efficient genome duplication across all domains of life

Prolactin as a modulator of antiparasitic immunity

Prolactin (PRL) is a polypeptide hormone of the pituitary origin, that expresses over 300 separate biological activities, including its involvement in the regulation of immune functions. The hormone's immune capacities are related, among others, to comitogenic activity, prevention of immune cell apoptosis, stimulation of interleukins and antibodies production. Prolactin acts as a potent positive modulator of immunity to some protozoan parasites. It is well established that the hormone stimulates IFN−g and many other TH1−type cytokines production during Toxoplasma gondii, Leishmania sp. and Acanthamoeba castellanii infections. Recent studies suggest that human prolactin may be a regulator of antiparasitic activity against Plasmodium falciparum. On the other hand pregnancy−associated hyperprolactinemia may have a relevant contribution to reactivation of latent infections caused by many helminthic parasites, like Ancylostoma sp. or Necator sp. It is possibly connected with the process of transmammary transmission of hookworm infection to breast−fed newborns. Moreover, an increase in endogenous circulating prolactin during late pregnancy and lactation in ewes infected with Haemonchus contortus, promotes the phenomenon of periparturient egg rise. High prolactin levels have also been seen in dairy cattle suffering from other trichostrongylids infections. In this article we have discussed the role of prolactin as an important regulator of immunity to parasites

The Influence of Cerium on the Hydrogen Storage Properties of La1-xCexNi5 Alloys

La1-xCexNi5 alloys (x = 0, 0.09, 0.25 and 0.5) were investigated in terms of their structures, phase contents, hydrogen storage properties and microhardness. It was confirmed that a cerium addition to the reference (LaNi5) alloy caused structural changes such as lattice shrinkage and, as a result, changed both the absorption and desorption pressures and the enthalpies of formation and decomposition. The alloy with the highest cerium content was found to possess a two-phase structure, probably as a result of nonequilibrium cooling conditions during its manufacturing process. The microhardness was found to increase to some extent with the cerium content and decrease for samples with the highest cerium content

Fatigue Tests and Metallographic of Explosively Cladded Steel-Titanium Bimetal/ Badania Zmęczeniowe I Metalograficzne Bimetalu Stal-Tytan Zgrzewanego Wybuchowo

The paper contains a description of fatigue life tests of titan-steel bimetal. The study involved specimens made of bimetal which was a combination of S355J2 steel and SB G1 265 titanium, which was imposed in the material by explosive cladding method. The research shows that the fatigue life of specimens made of native material, derived from cladded plate is less than the life of specimens of titanium-steel bimetalW pracy zawarto wyniki badań zmęczeniowych i metalograficznych bimetalu będącego połączeniem stali S355J2 z tytanem SB265G1 przy pomocy technologii zgrzewania wybuchowego. Analiza wyników badań dowodzi, że proces zgrzewania wybuchowego i obróbki cieplnej mają wpływ na trwałość zmęczeniowa materiału. Ponadto stwierdzono, że w procesie projektowania elementów narażonych na zmiennę obciążenia należy uwzględnić własności wszystkich materiałów wchodzących w skład plateru