Simple repetitive sequences in the genome: structure and functional significance

The current explosion of DNA sequence information has generated increasing evidence for the claim that noncoding repetitive DNA sequences present within and around different genes could play an important role in genetic control processes, although the precise role and mechanism by which these sequences function are poorly understood. Several of the simple repetitive sequences which occur in a large number of loci throughout the human and other eukaryotic genomes satisfy the sequence criteria for forming non-B DNA structures in vitro. We have summarized some of the features of three different types of simple repeats that highlight the importance of repetitive DNA in the control of gene expression and chromatin organization. (i) (TG/CA)n repeats are widespread and conserved in many loci. These sequences are associated with nucleosomes of varying linker length and may play a role in chromatin organization. These Z-potential sequences can help absorb superhelical stress during transcription and aid in recombination. (ii) Human telomeric repeat (TTAGGG)n adopts a novel quadruplex structure and exhibits unusual chromatin organization. This unusual structural motif could explain chromosome pairing and stability. (iii) Intragenic amplification of (CTG)n/(CAG)n trinucleotide repeat, which is now known to be associated with several genetic disorders, could down-regulate gene expression in vivo. The overall implications of these findings vis-à-vis repetitive sequences in the genome are summarized

Dye wastewater degradation by the synergetic effect of an atmospheric pressure plasma treatment and the photocatalytic activity of plasma-functionalized Cu-TiO2 nanoparticles

In this paper, the photocatalytic activity of plasma-functionalized Cu-doped TiO2 nanoparticles (NPs) and the oxidization process of atmospheric pressure plasma jet were combined for the degradation of reactive red-198 (RR-198) in aqueous solution. The first part of the study was thus devoted to subject Cu-TiO2 NPs synthetized by the sol-gel method to various plasma treatments operating in air, argon, oxygen and nitrogen to improve their degradation efficiency. The physicochemical properties of the NPs were then assessed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. XRD results indicated the predominant presence of the anatase phase which is the most photoactive form of TiO2. The XPS analysis revealed that the different plasma treatments triggered the formation of oxygen vacancies, Ti3+ oxidation state and Cu2+ oxidation state on the surface of Cu-TiO2 NPs. These changes, known to prevent the recombination of electron-hole pair, have led to a reduction in the bandgap that was more pronounced for the N-2 plasma-treated NPs. The second part of the paper explored the actual degradation of RR-198 in aqueous solution by an Ar plasma treatment alone or combined with the plasma pre-treated Cu-TiO2 NPs. Optical emission spectroscopy (OES) and spectrophotometric analyses showed that the synergetic effect of Ar plasma and N-2 plasma-treated NPs produced the highest concentration of OH center dot radicals and H2O2 species which led to the highest RR-198 degradation efficiency. This was further confirmed by pH, electrical conductivity and total organic carbon (TOC) removal measurements. The degradation of RR-198 was determined using UV-Vis spectroscopy and high-performance liquid chromatography (HPLC). Overall, it can be concluded that plasma-assisted processes illustrated by a combination of a direct plasma treatment with plasma-functionalized Cu-TiO2 NPs can be used in various textile and pharmaceutical industries as a highly effective treatment of their effluents before discharging

Weak ac field-induced patterns in vertical deposition of colloids at various evaporation rates

Pattern formation in colloids by weak ac fields in vertical deposition-like configuration at different temperatures has been studied experimentally. At low evaporation (room temperature), the effect of the field leads to the evolution of a one-dimensional array of clusters along the contact line and columnar colloidal dried deposits are obtained at higher evaporation. We investigate the flow dynamics involved in this pattern formation. Homogeneous variation of the contact angle by electrowetting effect becomes unstable and breaks the translational symmetry at the meniscus. Electrokinetic forces together with capillary forces result in the accumulation of particles for pattern formation. The movement of electrically charged colloidal particles is controlled by weak ac electric field even at higher temperatures. We observe the effect of increasing initial particle concentration on the behavior of the clusters for various field frequencies. The average distance between clusters increase monotonically with an increase in the initial particle concentration. We also observe that the average width of columns increases according to the applied field strength

Combinatorial effects of non-thermal plasma oxidation processes and photocatalytic activity on the inactivation of bacteria and degradation of toxic compounds in wastewater

The simultaneous presence of hazardous chemicals and pathogenic microorganisms in wastewater is tremendously endangering the environment and human health. Therefore, developing a mitigation strategy for adequately degrading toxic compounds and inactivating/killing microorganisms is urgently needed to protect ecosystems. In this paper, the synergetic effects of the photocatalytic activity of TiO2 and Cu-TiO2 nanoparticles (NPs) and the oxidation processes of non-thermal atmospheric pressure plasma (NTAPP) were comprehensively investigated for both the inactivation/killing of common water contaminating bacteria (Escherichia coli (E. coli)) and the degradation of direct textile wastewater (DTW). The photocatalytic NPs were synthesized using the hydrothermal method and further characterized employing field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS) and photoluminescence (PL). Results revealed the predominant presence of the typical anatase phase for both the flower-like TiO2 and the multipod-like Cu-TiO2 structures. UV-Vis DRS and PL analyses showed that the addition of Cu dopants reduced the bandgap and increased oxygen defect vacancies of TiO2. The inactivation of E. coli in suspension and degradation of DTW were then examined upon treating the aqueous media with various plasma alone and plasma/NPs conditions (Ar plasma, Ar + O-2 plasma and Ar + N-2 plasma, Ar plasma + TiO2 NPs and Ar plasma + Cu-TiO2 NPs). Primary and secondary excited species such as OH, O, H and N-2* generated in plasma during the processes were recognized by in situ optical emission spectrometry (OES) measurements. Several other spectroscopic analyses were further employed to quantify some reactive oxygen species (ROS) such as OH, H2O2 and O-3 generated during the processes. Moreover, the changes in the pH and electrical conductivity (EC) of the solutions were also assessed. The inactivation of bacteria was examined by the colony-forming unit (CFU) method after plating the treated suspensions on agar, and the degradation of organic compounds in DTW was further validated by measuring the total organic carbon (TOC) removal efficiency. All results collectively revealed that the combinatorial plasma-photocatalysis strategy involving Cu-TiO2 NPs and argon plasma jet produced higher concentrations of ROS and proved to be a promising one-step wastewater treatment effectively killing microorganisms and degrading toxic organic compounds

Mapping subtasks with multiple versions on an ad hoc grid

Includes bibliographical references (pages 688-690).An ad hoc grid is a heterogeneous computing system composed of mobile devices. Each computing resource is constrained in battery energy. The problem being studied is to assign statically computing resources to the subtasks of an application that has an execution time constraint, when the resources are oversubscribed. All subtasks must be executed; to accommodate this in an oversubscribed environment, each subtask has two versions: the primary or full version, and the secondary or degraded version. The secondary version utilizes only 10%of the resources that the primary version requires, and produces only 10% of the data output for the subsequent children subtasks. Thus, the degraded version (secondary version) represents a reduced capability of lesser overall value, while consuming fewer resources. The goal is to assign resources so that the application meets an execution time constraint and the battery energy constraint while minimizing the number of degraded versions used. Five resource allocation heuristics to derive near-optimal solutions to this problem are presented, evaluated, and compared

Evaluation of surface properties of low density polyethylene (LDPE) films tailored by atmospheric pressure non-thermal plasma (APNTP) assisted co-polymerization and immobilization of chitosan for improvement of antifouling properties

This work describes the development of antifouling functional coatings on the surface of low density polyethylene (LDPE) films by means of atmospheric pressure non-thermal plasma (APNTP) assisted copolymerization using a mixture of acrylic acid and poly (ethylene glycol). The aim of the study was to investigate the antifouling properties of the plasma copolymerized LDPE films and the same was carried out as a function of deposition time with fixed applied potential of 14 kV. In a second stage, the plasma copolymerized LDPE films were functionalized with chitosan (CHT) to further enhance its antifouling properties. The surface hydrophilicity, structural, topographical and chemistry of the plasma copolymerized LDPE films were examined by contact angle (CA), X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Coating stability was also studied in detail over a storage time of 15 days by storing in water and air. The antifouling properties of the plasma copolymerized LDPE films were examined via protein adsorption and platelet adhesion studies. CA study showed significant changes in surface wettability after the coating process. XPS and FTIR analysis proved the presence of a dense multifunctional coating and an efficient immobilization of CHT. Substantial amendments in surface topography were observed, positively enhancing the overall surface hydrophilicity. Finally, in-vitro analysis showed excellent antifouling behavior of the surface modified LDPE films

Tumour microenvironment factors shaping the cancer metabolism landscape

Cancer cells exhibit metabolic alterations that distinguish them from healthy tissues and make their metabolic processes susceptible to pharmacological targeting. Although typical cell-autonomous features of cancer metabolism have been emerging, it is increasingly appreciated that extrinsic factors also influence the metabolic properties of tumours. This review highlights evidence from the recent literature to discuss how conditions within the tumour microenvironment shape the metabolic character of tumours