Enhancement of nanoscale zero-valent iron immobilization onto electrospun polymeric nanofiber mats for groundwater remediation

© 2017 Institution of Chemical Engineers A new approach that combines nanoscale zero-valent iron (nZVI) with electrospinning technology has been put forward to avoid nZVI agglomeration and a secondary pollution. In this study, to enhance the immobilization of nZVI particles onto the polyacrylic acid (PAA)/polyvinyl alcohol (PVA) electrospun nanofiber mat, mats (M1, M2 and M3) with different PAA/PVA mass ratios (1:1, 2:1 and 3:1) were tested for the immobilization of nZVI particles and their performance of removing contaminants. The results indicate that M3 immobilized the most nZVI particles (48.4 wt% on the mat, ∼2.5 times the figure for previous study) and had the highest removals to methylene blue and Cu(II) ions at 94% and 83.6% respectively, resulting from more free carboxylic groups available on the cross-linked nanofibers as well as a higher porosity into the mat. Therefore, increasing the PAA/PVA ratio is effective to boost the performance of nZVI–PAA/PVA electrospun nanofiber mat, which has a great potential for the application of nZVI-targeted contaminants remediation

Characteristics of membrane fouling by consecutive chemical cleaning in pressurized ultrafiltration as pre-treatment of seawater desalination

© 2015 Elsevier B.V. Chemical cleaning of membranes is one of the most important strategies in pressurized hollow fiber ultrafiltration (UF) as a pre-treatment for seawater desalination. Various physical cleaning strategies such as backwashing, aeration and air-scrubbing or chemically enhanced backwashing (CEB) have been investigated in order to remove foulants from the UF membrane. However, the limitation in their cleaning effects being found during long-term operation leads to the need of cleaning in place (CIP) for the recovery of membrane performance. In this study, we used oxalic acid and sodium hypochlorite as chemical cleaning agents. The cleaning in series of oxalic acid-sodium hypochlorite-oxalic acid showed the optimal cleaning efficiency and was applied for the consecutive chemical cleaning. The recovery efficiency of the CIP after first, second, third and fourth cleanings was 96.8%, 95.8%, 98.3% and 99.9%, respectively. It was almost fully recovered to the previous recovered value. However, membrane surface structure was deformed by contact with chemical cleaning agents during cleaning time, because, hydrophilic inorganic foulants are still adhered on the membrane surface even after several cleanings although hydrophobic organic foulants were removed easily by chemical cleaning. An improved CIP strategy should be developed to remove hydrophilic foulants for long-term operation of desalination plants

Graphene/PVDF flat-sheet membrane for the treatment of RO brine from coal seam gas produced water by air gap membrane distillation

© 2016 Elsevier B.V. Brine management of coal seam gas (CSG) produced water is a significant concern for the sustainable production of CSG in Australia. Membrane distillation (MD) has shown the potential to further reduce the volume of CSG reverse osmosis (RO) brine. However, despite its potential, the lack of appropriate MD membranes limits its industrial use. Therefore, this study was aimed on the fabrication of a robust membrane for the treatment of real RO brine from CSG produced water via an air gap MD (AGMD) process. Here, graphene/polyvinylidene fluoride (G/PVDF) membranes at various graphene loadings 0.1-2.0 wt% w.r.t. to PVDF) were prepared through a phase inversion method. Surface characterization revealed that all G/PVDF membranes exhibited favorable membrane properties having high porosity (>78%), suitable mean pore size (3.66 bar). AGMD test results (feed inlet: 60.0±1.5 °C; coolant inlet: 20.0±1.5 °C) for 24 h operation indicated a high water vapor flux and salt rejection of 20.5 L/m2h and 99.99%, respectively for the optimal graphene loading of 0.5 wt%, i.e., G/PVDF-0.5 membrane (compared to 11.6 L/m2h and 99.96% for neat PVDF membrane). Long-term AGMD operation of 10 days further revealed the robustness of G/PVDF membrane with superior performance compared to commercial PVDF membrane (85.3% final normalized flux/99.99% salt rejection against 51.4%/99.95% for commercial membrane). Incorporation of graphene has resulted to improved wetting resistance and more robust membrane that has the potential for the treatment of RO brine from CSG produced water via AGMD

True Neutrality as a New Type of Flavour

A classification of leptonic currents with respect to C-operation requires the separation of elementary particles into the two classes of vector C-even and axial-vector C-odd character. Their nature has been created so that to each type of lepton corresponds a kind of neutrino. Such pairs are united in families of a different C-parity. Unlike the neutrino of a vector type, any C-noninvariant Dirac neutrino must have his Majorana neutrino. They constitute the purely neutrino families. We discuss the nature of a corresponding mechanism responsible for the availability in all types of axial-vector particles of a kind of flavour which distinguishes each of them from others by a true charge characterized by a quantum number conserved at the interactions between the C-odd fermion and the field of emission of the corresponding types of gauge bosons. This regularity expresses the unidenticality of truly neutral neutrino and antineutrino, confirming that an internal symmetry of a C-noninvariant particle is described by an axial-vector space. Thereby, a true flavour together with the earlier known lepton flavour predicts the existence of leptonic strings and their birth in single and double beta decays as a unity of flavour and gauge symmetry laws. Such a unified principle explains the availability of a flavour symmetrical mode of neutrino oscillations.Comment: 19 pages, LaTex, Published version in IJT

A practical guide to photoacoustic tomography in the life sciences

The life sciences can benefit greatly from imaging technologies that connect microscopic discoveries with macroscopic observations. One technology uniquely positioned to provide such benefits is photoacoustic tomography (PAT), a sensitive modality for imaging optical absorption contrast over a range of spatial scales at high speed. In PAT, endogenous contrast reveals a tissue's anatomical, functional, metabolic, and histologic properties, and exogenous contrast provides molecular and cellular specificity. The spatial scale of PAT covers organelles, cells, tissues, organs, and small animals. Consequently, PAT is complementary to other imaging modalities in contrast mechanism, penetration, spatial resolution, and temporal resolution. We review the fundamentals of PAT and provide practical guidelines for matching PAT systems with research needs. We also summarize the most promising biomedical applications of PAT, discuss related challenges, and envision PAT's potential to lead to further breakthroughs

On dynamic network entropy in cancer

The cellular phenotype is described by a complex network of molecular interactions. Elucidating network properties that distinguish disease from the healthy cellular state is therefore of critical importance for gaining systems-level insights into disease mechanisms and ultimately for developing improved therapies. By integrating gene expression data with a protein interaction network to induce a stochastic dynamics on the network, we here demonstrate that cancer cells are characterised by an increase in the dynamic network entropy, compared to cells of normal physiology. Using a fundamental relation between the macroscopic resilience of a dynamical system and the uncertainty (entropy) in the underlying microscopic processes, we argue that cancer cells will be more robust to random gene perturbations. In addition, we formally demonstrate that gene expression differences between normal and cancer tissue are anticorrelated with local dynamic entropy changes, thus providing a systemic link between gene expression changes at the nodes and their local network dynamics. In particular, we also find that genes which drive cell-proliferation in cancer cells and which often encode oncogenes are associated with reductions in the dynamic network entropy. In summary, our results support the view that the observed increased robustness of cancer cells to perturbation and therapy may be due to an increase in the dynamic network entropy that allows cells to adapt to the new cellular stresses. Conversely, genes that exhibit local flux entropy decreases in cancer may render cancer cells more susceptible to targeted intervention and may therefore represent promising drug targets.Comment: 10 pages, 3 figures, 4 tables. Submitte

The Angular Dependence of the Critical Current of BaCeO3 Doped YBa2Cu3O6+x Thin Films

The angular dependencies of the critical current of BaCeO3 (BCO) doped YBa2Cu3O6+x (YBCO) thin films grown with pulsed laser deposition (PLD) on SrTiO3 (001) were systematically investigated. The BCO concentration in the YBCO matrix was varied between 0-8 wt.%. Transmission electron microscopy confirmed that the 4% BCO containing sample has point-like, partly agglomerated BCO particles with diameter of 2.5 nm. The dopant degrades the crystal quality of YBCO but improves its in-field current carrying performance especially at low temperatures. The BCO addition affects the angular dependence of the critical current by broadening the B parallel to ab-axis peak of YCBO but no c-axis peak is seen, which is contrary to BaZrO3 doped films made by PLD. Although the particles are point-like, it is found that a model featuring only isotropic pinning centers is not sufficient to describe the angular dependence of the samples where B parallel to ab-axis of YCBO.</p

Educational paper: Primary immunodeficiencies in children: a diagnostic challenge

Primary immunodeficiencies (PIDs) are characterized by an increased susceptibility to infections due to defects in one ore more components of the immune system. Although most PIDs are relatively rare, they are more frequent than generally acknowledged. Early diagnosis and treatment of PIDs save lives, prevent morbidity, and improve quality of life. This early diagnosis is the task of the pediatrician who encounters the child for the first time: he/she should suspect potential PID in time and perform the appropriate diagnostic tests. In this educational paper, the first in a series of five, we will describe the most common clinical presentations of PIDs and offer guidelines for the diagnostic process, as well as a brief overview of therapeutic possibilities and prognosis

Differential Proteomic Analysis of Platelets Suggested Possible Signal Cascades Network in Platelets Treated with Salvianolic Acid B

Salvianolic acid B (SB) is an active component isolated from Danshen, a traditional Chinese medicine widely used for the treatment of cardiovascular disorders. Previous study suggested that SB might inhibit adhesion as well as aggregation of platelets by a mechanism involving the integrin α2β1. But, the signal cascades in platelets after SB binding are still not clear.In the present study, a differential proteomic analysis (two-dimensional electrophoresis) was conducted to check the protein expression profiles of rat platelets with or without treatment of SB. Proteins altered in level after SB exposure were identified by MALDI-TOF MS/MS. Treatment of SB caused regulation of 20 proteins such as heat shock-related 70 kDa protein 2 (hsp70), LIM domain protein CLP-36, copine I, peroxiredoxin-2, coronin-1 B and cytoplasmic dynein intermediate chain 2C. The regulation of SB on protein levels was confirmed by Western blotting. The signal cascades network induced by SB after its binding with integrin α2β1 was predicted. To certify the predicted network, binding affinity of SB to integrin α2β1 was checked in vitro and ex vivo in platelets. Furthermore, the effects of SB on protein levels of hsp70, coronin-1B and intracellular levels of Ca²+ and reactive oxygen species (ROS) were checked with or without pre-treatment of platelets using antibody against integrin α2β1. Electron microscopy study confirmed that SB affected cytoskeleton structure of platelets.Integrin α2β1 might be one of the direct target proteins of SB in platelets. The signal cascades network of SB after binding with integrin α2β1 might include regulation of intracellular Ca²+ level, cytoskeleton-related proteins such as coronin-1B and cytoskeleton structure of platelets

Acellular Bone Marrow Extracts Significantly Enhance Engraftment Levels of Human Hematopoietic Stem Cells in Mouse Xeno-Transplantation Models

Hematopoietic stem cells (HSC) derived from cord blood (CB), bone marrow (BM), or mobilized peripheral blood (PBSC) can differentiate into multiple lineages such as lymphoid, myeloid, erythroid cells and platelets. The local microenvironment is critical to the differentiation of HSCs and to the preservation of their phenotype in vivo. This microenvironment comprises a physical support supplied by the organ matrix as well as tissue specific cytokines, chemokines and growth factors. We investigated the effects of acellular bovine bone marrow extracts (BME) on HSC in vitro and in vivo. We observed a significant increase in the number of myeloid and erythroid colonies in CB mononuclear cells (MNC) or CB CD34+ cells cultured in methylcellulose media supplemented with BME. Similarly, in xeno-transplantation experiments, pretreatment with BME during ex-vivo culture of HSCs induced a significant increase in HSC engraftment in vivo. Indeed, we observed both an increase in the number of differentiated myeloid, lymphoid and erythroid cells and an acceleration of engraftment. These results were obtained using CB MNCs, BM MNCs or CD34+ cells, transplanted in immuno-compromised mice (NOD/SCID or NSG). These findings establish the basis for exploring the use of BME in the expansion of CB HSC prior to HSC Transplantation. This study stresses the importance of the mechanical structure and soluble mediators present in the surrounding niche for the proper activity and differentiation of stem cells