Phospholipid‐Free Small Unilamellar Vesicles for Drug Targeting to Cells in the Liver

It is reported that cholesterol (Chol) and TWEEN 80 at a molar ratio of 5:1 can form small unilamellar vesicles (SUVs) using a staggered herringbone micromixer. These phospholipid‐free SUVs (PFSUVs) can be actively loaded with a model drug for targeting hepatocytes via the endogenous apolipoprotein mechanism. PFSUVs particles with compositions of Chol:TWEEN 80 ranging between 1.5:1 and 5:1 (mol/mol) can be produced with a mean diameter of ≈80 nm, but only the high‐Chol formulations (3:1 and 5:1) can retain a transmembrane gradient of ammonium sulfate for active loading of doxorubicin (DOX). Under cryo‐transmission electron microscopy, PFSUVs‐DOX displays a unilamellar bilayer structure with DOX molecules forming spindle‐shape aggregates inside the aqueous core. Relative to PEGylated liposomal doxorubicin (PLD) that exhibits little interaction with cells in various conditions, the cellular uptake of PFSUVs‐DOX is dependent on the presence of serum and enhanced with an increased concentration of apolipoproteins. After intravenous injection, the vast majority of PFSUVs‐DOX accumulates in the liver and DOX is detected in all liver cells (predominantly the hepatocytes), while PLD is captured only by the sinusoidal cells (i.e., macrophages). This report discloses an innovative lipid bilayer vesicle for highly efficient and selective hepatocyte targeting.     

Quantifying uncertainty in estimation of hydrologic metrics for ecohydrological studies

Hydrologic metrics have been used extensively in ecology and hydrology to summarize the characteristics of riverine flow regimes at various temporal scales but there has been limited evaluation of the sources and magnitude of uncertainty involved in their computation. Variation in bias, precision and overall accuracy of these metrics influences the ability to correctly describe flow regimes, detect meaningful differences in hydrologic characteristics through time and space, and define flow‐ecological response relationships. Here, we examine the effects of two primary factors—discharge record length and time period of record—on uncertainty in the estimation of 120 separate hydrologic metrics commonly used by researchers to describe ecologically relevant components of the hydrologic regime. Metric bias rapidly decreased and precision and overall accuracy markedly increased with increasing record length, but tended to stabilize >15 years and did not change substantially >30 years. We found a strong positive relationship between the degree of overlap of discharge record and similarity in hydrologic metrics when based on 15‐ and 30‐year discharge periods calculated within a 36‐year temporal window (1965–2000), although hydrologic metrics calculated for a given stream gauge tended to vary only within a restricted range through time. Our study provides critical guidance for selecting an appropriate record length and temporal period of record given a degree of metric bias and precision deemed acceptable by a researcher. We conclude that: (1) estimation of hydrologic metrics based on at least 15 years of discharge record is suitable for use in hydrologic analyses that aim to detect important spatial variation in hydrologic characteristics; (2) metric estimation should be based on overlapping discharge records contained within a discrete temporal window (ideally >50% overlap among records); and (3) metric uncertainty varies greatly and should be accounted for in future analyses. Copyright © 2009 John Wiley & Sons, Ltd.     

A strategic framework for improving food security in Arab countries

In 2007 and the first half of 2008, a sharp rise in agricultural commodity and food prices triggered grave concerns about food security, malnutrition and increased poverty. While the threat of a prolonged food-price shock receded in the second half of 2008, many factors underlying the price volatility are likely to persist, and will require careful management if future food-price shocks are to be avoided. This paper suggests three strategies that, together, could reduce vulnerability to price shocks: (1) strengthen safety nets, improve access to family planning services, and promote education; (2) enhance domestic food production and improve rural livelihoods through increased investment in research and development to increase productivity; and (3) reduce exposure to market volatility through more efficient supply chains and better use of financial instruments to hedge risk. The challenge of food security will require a global response, involving governments, international and regional funding and lending institutions, United Nations agencies, non-governmental organizations, civil society, and the private sector.     

Theoretical efficiency limits for energy conversion devices

Using energy more efficiently is a key strategy for reducing global carbon dioxide emissions. Due to limitations on time and resources, actions must be focused on the efficiency measures which will deliver the largest gains. Current surveys of energy efficiency measures assess only known technology options developed in response to current economic and technical drivers. However, this ignores opportunities to deliver long-term efficiency gains from yet to be discovered options. In response, this paper aims to calculate the absolute potential for reducing energy demand by improving efficiency, by finding the efficiency limits for individual conversion devices and overlaying these onto the global network of energy flow. The potential efficiency gains for each conversion device are found by contrasting current energy demand with theoretical minimum energy requirements. Further insight is gained by categorising conversion losses according to the underlying loss mechanisms. The result estimates the overall efficiency of global energy conversion to be only 11 per cent; global demand for energy could be reduced by almost 90 per cent if all energy conversion devices were operated at their theoretical maximum efficiency.     

Comparative Study of Capsaicinoid Composition in Capsicum Peppers Grown in Brazil

Twenty different varieties of Capsicum pepper cultivars belonging to four species (Capsicum chinense, Capsicum annuum, Capsicum frutescens, and Capsicum baccatum) were characterized in terms of their capsaicinoid and total phenolic content. The peppers were sown in a farm in the southeastern region of São Paulo State. The determination of capsaicinoids was performed by ultra-performance liquid chromatography. The total phenolic content was determined spectrophotometrically with the Folin-Ciocalteu reagent. Results were expressed as µg capsaicinoid/g fresh pepper and as Scoville heat unit. A wide variation was observed among the compositions of capsaicinoids. Capsaicin and dihydrocapsaicin were the most abundant peaks. Capsaicinoids were not identified in the pepper varieties Cheiro Verde, Cambuci Verde, Cambuci Vermelha, and Biquinho. The spiciest pepper was Naga Jolokia (119,016 Scoville heat unit). Regarding the phenolic contents, a large variability was observed. Total phenolic content ranged from 0.35 mg gallic acid equivalent/g in Cambuci Verde to 3.06 mg gallic acid equivalent/g in Naga Jolokia. The current study may benefit consumers, the food, and pharmaceutical industries due to the increasing interest in pharmacological compounds present in hot and sweet Capsicum peppers.     

Formation of Food‐Grade Nanoemulsions Using Low‐Energy Preparation Methods: A Review of Available Methods

There is considerable interest in the production of emulsions and nanoemulsions using low‐energy methods due to the fact they are simple to implement and no expensive equipment is required. In this review, the principles of isothermal (spontaneous emulsification and emulsion phase inversion) and thermal (phase inversion temperature) low‐energy methods for nanoemulsion production are presented. The major factors influencing nanoemulsion formation using low‐energy methods and food‐grade components are reviewed: preparation conditions, oil type, surfactant type, surfactant‐to‐oil ratio, and cosolvent or cosurfactant addition. The advantages and disadvantages of different low‐energy and high‐energy methods for fabricating nanoemulsions are highlighted, and potential applications for these techniques are discussed.     

Controlling ion release from bioactive glass foam scaffolds with antibacterial properties

Bioactive glass scaffolds have been produced, which meet many of the criteria for an ideal scaffold for bone tissue engineering applications, by foaming sol-gel derived bioactive glasses. The scaffolds have a hierarchical pore structure that is very similar to that of cancellous bone. The degradation products of bioactive glasses have been found to stimulate the genes in osteoblasts. This effect has been found to be dose dependent. The addition of silver ions to bioactive glasses has also been investigated to produce glasses with bactericidal properties. This paper discusses how changes in the hierarchical pore structure affect the dissolution of the glass and therefore its bioactivity and rate of ion delivery and demonstrates that silver containing bioactive glass foam scaffolds can be synthesised. It was found that the rate of release of Si and Ca ions was more rapid for pore structures with a larger modal pore diameter, although the effect of tailoring the textural porosity on the rate of ion release was more pronounced. Bioactive glass scaffolds, containing 2 mol% silver, released silver ions at a rate that was similar to that which has previously been found to be bactericidal but not high enough to be cytotoxic to bone cells.     

Possibility of imaging lateral profiles of individual tetrahedral hybrid orbitals in real space

The imaging mechanism of scanning tunnelling microscopy (STM) and non-contact atomic force microscopy (NC-AFM) has the same origin, that is, the interaction between the electronic states of the tip and the electronic states of the sample. Therefore, using a well-characterized sample, the tip electronic states become the object to be probed by both STM and AFM. In this paper, we will present an analytic approach to compute the force distribution and the tunnelling-conductance distribution. As an example, we predict the possibility of resolving the lateral profiles of the tetrahedral hybrid orbitals, which are the foundation of many important materials essential to industry and life. We will discuss the conditions under which it could be observed, together with the issue of reproducibility.