Liquid flow and mixing in concentric tube air-lift reactors

Liquid velocity and mixing were measured in two concentric tube air-lift reactors (ALR) of 30 and 300 dm³ (nominal volume). The influences of the geometrical design and the reactor scale were studied as a function of gas flow rates. The mixing in the 30 dm³ ALR, which had an enlarged cross-sectional area in the gas separator region, indicates that in this geometrical configuration most of the mixing occurs in this region. It is demonstrated that the location of the injection and measuring points influence the measurement of mixing time in air-lift reactors. Correlations for pressure drop at the bottom, gas hold-up and mass transfer coefficients, which were published in a previous paper, are extended to include the effect of the ratio of downcomer-to-riser cross-sectional areas.     

Drug delivery: Layer‐By‐Layer‐Assembled Capsules and Films for Therapeutic Delivery (Small 17/2010)

Polymeric materials formed via layer‐by‐layer (LbL) assembly have promise for use as drug delivery vehicles. These multilayered materials, both as capsules and thin films, can encapsulate a high payload of toxic or sensitive drugs, and can be readily engineered and functionalized with specific properties. This review highlights important and recent studies that advance the use of LbL‐assembled materials as therapeutic devices. It also seeks to identify areas that require additional investigation for future development of the field. A variety of drug‐loading methods and delivery routes are discussed. The biological barriers to successful delivery are identified, and possible solutions to these problems are discussed. Finally, state‐of‐the‐art degradation and cargo release mechanisms are also presented.     

Ceramic processing strategies for thick films on copper foils

Functional oxides on Cu have multiple applications. For thick films the required high sintering temperatures present a challenge for processing on base metal substrates. In this study it is shown that it is possible to adapt well-known ceramic processing strategies to the fabrication of thick lead zirconate titanate (PZT) films on Cu with useful ferroelectric properties. PZT powders with optimized particle sizes are used to fabricate thick films by electrophoretic deposition in combination with a post-deposition isostatic pressing step. This approach to maximize green packing is sufficient to dramatically lower the required sintering temperatures. 25 μm thick PZT films on Cu sintered at 900 °C have a dielectric permittivity of 585, a loss tangent at 10 kHz of 0.03, a remanent polarization of 19 μC cm^?2 and a coercive field of 22 kV cm^?1. This significant improvement in the dielectric response opens the possibility of using thick PZT films on Cu for a wide range of devices where cost, yield and reliability are concerns.     

The Apotropaic “Witch posts” of Early Modern Yorkshire: A Contextualization

In houses in Yorkshire there remain carved posts of some antiquity, marked with a distinct X, whose provenance is unknown. These are known locally as “witch posts.” Understanding these as examples of apotropaic folk-belief is recommended by contemporary accounts of the necessity of protection against evil by charms, images, and objects. Such beliefs were not only not marginal but actively encouraged by both traditional church practices and a Neoplatonic conception of the potency of words, incantations, and charms in physical and spiritual matters. That these ideas have resisted the pressure of the skeptical and rational discourses with which they have been approached is partly testament to the shifting signification of the posts themselves.     

A functional flows approach to selecting ecologically relevant flow metrics for environmental flow applications

The science and practice of environmental flows have advanced significantly over the last several decades. Most environmental flow approaches require quantifying the relationships between hydrologic change and biologic response, but this can be challenging to determine and implement due to high data requirements, limited transferability, and the abundance of hydrologic metrics available for evaluation. We suggest that a functional flows approach, focusing on elements of the natural flow regime known to sustain important ecosystem processes, offers a pathway for linking understanding of ecosystem processes with discrete, quantifiable measures of the flow regime for a broad range of native taxa and assemblages. Functional flow components can be identified as distinct aspects of the annual hydrograph that support key biophysical processes, such as wet season flood flows or spring recession flows, and then quantified by flow metrics, such as 5% exceedance flow or daily percent decrease in flow, respectively. By selecting a discrete set of flow metrics that measure key functional flow components, the spatial and temporal complexity of flow regimes can be managed in a holistic manner supportive of multiple ecological processes and native aquatic species requirements. We provide an overview of the functional flows approach to selecting a defined set of flow metrics and illustrate its application in two seasonally variable stream systems. We further discuss how a functional flows approach can be utilized as a conceptual model both within and outside of existing environmental flow frameworks to guide consideration of ecological processes when designing prescribed flow regimes.     

Adenovirus Terminal Protein Contains a Bipartite Nuclear Localisation Signal Essential for Its Import into the Nucleus

Adenoviruses contain dsDNA covalently linked to a terminal protein (TP) at the 5′end. TP plays a pivotal role in replication and long-lasting infectivity. TP has been reported to contain a nuclear localisation signal (NLS) that facilitates its import into the nucleus. We studied the potential NLS motifs within TP using molecular and cellular biology techniques to identify the motifs needed for optimum nuclear import. We used confocal imaging microscopy to monitor the localisation and nuclear association of GFP fusion proteins. We identified two nuclear localisation signals, PV(R)6VP and MRRRR, that are essential for fully efficient TP nuclear entry in transfected cells. To study TP–host interactions further, we expressed TP in Escherichia coli (E. coli). Nuclear uptake of purified protein was determined in digitonin-permeabilised cells. The data confirmed that nuclear uptake of TP requires active transport using energy and shuttling factors. This mechanism of nuclear transport was confirmed when expressed TP was microinjected into living cells. Finally, we uncovered the nature of TP binding to host nuclear shuttling proteins, revealing selective binding to Imp β, and a complex of Imp α/β but not Imp α alone. TP translocation to the nucleus could be inhibited using selective inhibitors of importins. Our results show that the bipartite NLS is required for fully efficient TP entry into the nucleus and suggest that this translocation can be carried out by binding to Imp β or Imp α/β. This work forms the biochemical foundation for future work determining the involvement of TP in nuclear delivery of adenovirus DNA.     

Matching programme structure to environment: A comparative study of two IS-based change programmes

This paper critically examines programme structure as a dimension of programme strategy within the context of large-scale-multi-site (LSMS) information system (IS) based change programmes. While a centralized programme structure is often assumed both in literature and in practice, we argue that programme structure should be a strategic decision contingent upon programme environment. Following the structural contingency theory, we characterise programme environment by two dimensions of the programme environment as programme authority over the participating organizations and homogeneity of the business processes among the participating organizations. Based on these two dimensions, we develop an authority-homogeneity matrix. Given a programme of low authority and low homogeneity, the programme should adopt a matching decentralized structure supported by standard process and data interfaces. By comparing two programme cases, we demonstrate how a decentralized approach can work for a LSMS IS-based change programme while a centralized programme structure fails.     

Common tea formulations modulate in vitro digestive recovery of green tea catechins

Epidemiological evidence suggests a role for tea catechins in reduction of chronic disease risk. However, stability of catechins under digestive conditions is poorly understood. The objective of this study was to characterize the effect of common food additives on digestive recovery of tea catechins. Green tea water extracts were formulated in beverages providing 4.5, 18, 23, and 3.5 mg per 100 mL epicatechin (EC), epigallocatechin (EGC), epigallocatechin-gallate (EGCG), and epicatechin-gallate (ECG), respectively. Common commercial beverage additives; citric acid (CA), BHT, EDTA, ascorbic acid (AA), milk (bovine, soy, and rice), and citrus juice (orange, grapefruit, lemon, and lime) were formulated into finished tea beverages at incremental dosages. Samples were then subjected to in vitro digestion simulating gastric and small intestinal conditions with pre- and post-digestion catechin profiles assessed by HPLC. Catechin stability in green tea was poor with <20% total catechins remaining post-digestion. EGC and EGCG were most sensitive with less, not double equals 10% recovery. Teas formulated with 50% bovine, soy, and rice milk increased total catechin recovery significantly to 52, 55, and 69% respectively. Including 30 mg AA in 250 mL of tea beverage significantly (p<0.05) increased catechin recovery of EGC, EGCG, EC, and ECG to 74, 54, 82, and 45% respectively. Juice preparation resulted in the highest recovery of any formulation for EGC (81-98%), EGCG (56-76%), EC (86-95%), and ECG (30-55%). These data provide evidence that tea consumption practices and formulation factors likely impact catechin digestive recovery and may result in diverse physiological profiles.