A short overview of bubbles in foods and chocolate.

The incorporation of bubbles in foods has created a positive market response from consumers since their first introduction over 70 years ago and has resulted in an expanding market over this period. However, although the physics and chemistry of most ingredients in commercial food products are reasonably well understood, the behaviour of bubbles in foods are much less established and their behaviour not fully appreciated. In fact, bubbles are perhaps the least studied of all food ingredients even though aeration is still one of the fastest growing unit operations in processing. Although many of these manufactured aerated food products are perceived as lighter with lower calorific values, problems in manufacturing remain even today and it is generally difficult to optimize the size, the size distribution, the deviation the from spherical shapes and the stability of the bubbles during the different stages of the processing. In this review, we discuss the dispersion of the various food ingredients and the different processes involved in introducing bubbles into the melt, producing well dispersed multiphase systems. The second part of this review focusses on aerated chocolate and the above aspects are particularly important and are discussed in some detail since it has been well established that the bubble size and size distribution can influence the texture, the mouthfeel, the crispness, the melting temperature, and the brittleness of the product. Understanding the science involved in the transformation from the liquid state containing dispersed bubbles to a solid chocolate foam, stabilization of the bubbles and the control of the bubble size are highlighted. Although CO2 is usually used to generate bubbles in chocolate, several different gases including N2O, Ar and N2 have also been evaluated. One of the research aims of food companies is to improve control over the stability of the systems. This has been investigated with respect to drainage, by carrying out experiments under zero gravity conditions.

Frontal fibrosing alopecia: survey of severity assessment methods in routine clinical practice and validation of the International Frontal Fibrosing Alopecia Cooperative Group measurement guidance.

BACKGROUND: The lack of validated and responsive outcome measures in the management of frontal fibrosing alopecia (FFA) significantly limits assessment of disease progression and treatment response over time. AIM: To understand how FFA extent and progression is currently assessed in UK specialist centres, to validate components of the International FFA Cooperative Group (IFFACG) statement on FFA assessment, and to identify pragmatic advice to improve FFA management in clinic. METHODS: Consultant dermatologists with a specialist interest in hair loss (n = 17) were invited to take part. Preferred FFA assessment methods were explored using questionnaires and clinical scenarios. Participants were asked to identify and mark the current hairline in 10 frontal and 10 temporal hairline images (Questionnaire 1), with assessment repeated 3 months later to assess intraindividual variability (Questionnaire 2) and 12 months later to test whether interindividual accuracy could be improved with simple instruction (Questionnaire 3). RESULTS: All 17 clinicians (100%) completed the questionnaire at each time interval. We identified a wide variation in assessment techniques used by our experts. Measurements were perceived as the most accurate method of assessing frontal recession whereas photography was preferred for temporal recession. Inter-rater reliability between clinicians measuring the frontal hairline scenarios indicated a moderate strength of agreement [intraclass coefficient (ICC) = 0.61; 95% CI 0.40-0.85], yet intrarater reliability was found to be poor with wide limits of agreement (-8.71 mm to 9.92 mm) on follow-up. Importantly, when clear guidance was provided on how the hairline should be identified (Questionnaire 3), inter-rater reliability improved significantly, with ICC = 0.70, suggesting moderate agreement (95% CI 0.51-0.89; P < 0.001). A similar pattern was seen with temporal hairline measurements, which again improved in accuracy with instruction. CONCLUSION: We found that accuracy of measurements in FFA can be improved with simple instruction and we have validated components of the IFFACG measurement recommendations.

Density-Driven Flows in Evaporating Binary Liquid Droplets.

In the evaporation of microlitre liquid droplets, the accepted view is that surface tension dominates and the effect of gravity is negligible. We report, through the first use of rotating optical coherence tomography, that a change in the flow pattern and speed occurs when evaporating binary liquid droplets are tilted, conclusively showing that gravitational effects dominate the flow. We use gas chromatography to show that these flows are solutal in nature, and we establish a flow phase diagram demonstrating the conditions under which different flow mechanisms occur.

Magnetic Levitation Stabilized by Streaming Fluid Flows.

We demonstrate that the ubiquitous laboratory magnetic stirrer provides a simple passive method of magnetic levitation, in which the so-called "flea" levitates indefinitely. We study the onset of levitation and quantify the flea's motion (a combination of vertical oscillation, spinning and "waggling"), finding excellent agreement with a mechanical analytical model. The waggling motion drives recirculating flow, producing a centripetal reaction force that stabilized the flea. Our findings have implications for the locomotion of artificial swimmers and the development of bidirectional microfluidic pumps, and they provide an alternative to sophisticated commercial levitators.

Low-Temperature Deposition Modeling of ß-TCP Scaffolds with Controlled Bimodal Porosity.

Low-temperature deposition modeling (LDM), otherwise termed freeze-form extrusion fabrication or rapid freeze prototyping, involves dispensing an aqueous-based ceramic paste or polymeric hydrogel along predefined paths in subzero ambient temperatures, followed by freeze-drying. The solidification of the material after the deposition of each layer enables large parts to be built without the need for organic binders, which can often have cytotoxic effects. Freeze-dried parts obtained from LDM typically exhibit pores with openings that range in average between 1 and 40 µm. The technique offers the ability to control their size distribution and orientation through varying a number of processing and material parameters. Herein, we describe the construction of an LDM system from readily available electromechanical components, as well as the preparation of a ß-ΤCP paste formulation with the appropriate flow characteristics for fabricating hierarchical scaffolds with tailorable bimodal porosity for applications in bone tissue engineering.

Controlling and characterising the deposits from polymer droplets containing microparticles and salt.

A coffee ring-stain is left behind when droplets containing a wide range of different suspended particles evaporate, caused by a pinned contact line generating a strong outwards capillary flow. Conversely, in the very peculiar case of evaporating droplets of poly(ethylene oxide) solutions, tall pillars are deposited in the centre of the droplet following a boot-strapping process in which the contact line recedes quickly, driven by a constricting collar of polymer crystallisation: no other polymer has been reported to produce these central pillars. Here we map out the phase behaviour seen when the specific pillar-forming polymer is combined with spherical microparticles, illustrating a range of final deposit shapes, including the standard particle ring-stain, polymer pillars and also flat deposits. The topologies of the deposits are measured using profile images and stylus profilometery, and characterised using the skewness of the profile as a simple analytic method for quantifying the shapes: pillars produce positive skew, flat deposits have zero skew and ring-stains have a negative value. We also demonstrate that pillar formation is even more effectively disrupted using potassium sulphate salt solutions, which change the water from a good solvent to a theta-point solvent, consequently reducing the size and configuration of the polymer coils. This inhibits polymer crystallisation, interfering with the bootstrap process and ultimately prevents pillars from forming. Again, the deposit shapes are quantified using the skew parameter.

Microbicides for HIV/AIDS. 3. Observation of apparent dynamic protonation and deprotonization in CD4+ T-cell model systems.

New measurements of the electrophoretic mobility of T-cell model systems have been carried out and analyzed to obtain the dynamic variation in mobility in small titration increments during separate upscale and downscale sweeps in pH. We demonstrate that a plot of plambda vs p[NaCl] has been found essential in evaluating the consistency of electrophoretic mobility measurements at different (1:1) electrolyte concentrations and show, for the first time, that electrophoretic mobility measurements as a function of pH can reflect different rates of the respective ionization and association that occur in the surface functional groups as a consequence of the different changes in the hydration-dehydration reactions involved. Differences found between the upscale and downscale sweeps suggest that it is easier to protonate a protein cell surface than to deprotonate it. The effect is most pronounced at the highest salt concentration (similar to that which exists for the cells in their native state) and becomes less pronounced as the salt concentration is lowered. The effect is interpreted as a result of the different changes in the state of hydration as a proton moves from the bulk through the double layer to a surface group and the reverse. The effect occurs with both replicating and activated T-cells. This latter result may be of biological significance and particularly relevant to HIV-1 infection, since during male-to-female transmission, the environment where most infections occur supports this protonation effect.

Comparison of patch test results among white Europeans and patients from the Indian subcontinent living within the same community.

BACKGROUND: There are few studies comparing the incidence of allergic contact dermatitis among different racial groups living within the same community. OBJECTIVES: The objectives of this study were to compare white European patients with Fitzpatrick's skin phototypes (FSP) I to IV and patients from Indian, Pakistan and Bangladesh with FSP V living within the same community. Referral rates for patch testing, incidence of contact allergies and differences in contact allergens found were assessed. METHOD: All patients referred to the Contact Dermatitis Unit at Dewsbury and District Hospital between 2004 and 2006, inclusive, were included in the study. All patients were patch tested to the British Contact Dermatitis Society standard series, plus other series according to their clinical history, occupational history and clinical findings. RESULTS: Four hundred and thirty-five consecutive patients from the patch testing clinic were included in the study. Fewer patients from the Indian subcontinent underwent patch testing (11.5%) than would have been expected for the size of the local population (18%). Fewer patients from the Indian subcontinent (44%) had one or more positive reactions compared with the white European patients (56%). No significant differences in the contact allergens responsible were detected between the two racial groups. CONCLUSION: There is a lower incidence of positive patch test results among patients with racial origins from the Indian subcontinent compared with white Europeans. This modest difference could be explained by a lower average age within the study population, and increased or differing exposure to contact allergens rather than demonstration of variability in the susceptibility to develop contact sensitivities following equal exposure.

Microbicides for HIV/AIDS. 2. Electrophoretic fingerprinting of CD4+ T-cell model systems.

New measurements of the dependence of the surface charge on the pH and electrolyte concentration for three living human white blood cell lines that are the principal targets of the HIV-1 virus are reported. Comparison of the electrophoretic fingerprint (EF) pattern, especially the line of zero mobility, with that of reference colloids establishes the separate individual identities and shows that all three exhibit a zwitterionic surface. With the EF results as a guide, preliminary biological infectivity measurements showed that small polyvalent cations modulate the negative charge on the T-cell surface in a way that strongly affects the infection kinetics. H9 cells were exposed to an infectious virus (X4), and the data showed that HIV interaction with target cells is enhanced by physiological fluids. The nondestructive methodology described is generally applicable to characterization of the surface charge and determination of the colloidal stability of any aqueous charged colloidal system without reference to any model of the double layer.

Apolipoprotein E gene polymorphisms are associated with psoriasis but do not determine disease response to acitretin.

BACKGROUND: Psoriasis is associated with abnormal plasma lipid metabolism and a high frequency of cardiovascular events. Increased lipid levels are also seen in patients with psoriasis treated with acitretin. Apolipoprotein E (ApoE) variants have been linked to hypertriglyceridaemia and hypercholesterolaemia in normal individuals. Two coding single nucleotide polymorphisms at +3937 and +4075 define the three common ApoE alleles e2, e3 and e4. OBJECTIVES: To test the hypothesis that particular ApoE polymorphism(s) are associated with psoriasis and that specific ApoE allelic variant(s) may be a marker for predicting disease response to acitretin. METHODS: DNA was genotyped for ApoE polymorphisms using a radioactive hybridization technique in cohorts of patients with psoriasis, including patients with chronic plaque psoriasis (CPP, n = 212), guttate psoriasis (GP, n = 94), palmoplantar pustulosis (PPP, n = 101), controls (n = 137), acitretin responders (n =106) and acitretin nonresponders (n = 84). RESULTS: The frequency of the e4 allele (+3937C/+4075C) was significantly higher in patients with CPP and GP than in controls (P = 0.008 and P = 0.02, respectively). There was no significant difference in allele frequencies between patients with PPP and controls. Allelic distribution was similar in acitretin responders and nonresponders. CONCLUSIONS: These data demonstrate an association between the Apo e4 allele and CPP and GP, suggesting a possible pathogenic role for ApoE in psoriasis. Our results do not support a link between disease response to acitretin and the e2, e3 or e4 allelic variants of ApoE.

Microbicides for HIV/AIDS. 1. Electrophoretic fingerprinting the H9 cell model system.

An electrophoretic fingerprint of a CD4+ T-cell (H9) has been produced for the first time. Samples were taken from three separate cultures prepared at different times to obtain a general characterization of the cells. The availability of commercial instrumentation equipped with an auto-titrator has made possible the application of both the 2-dimensional and 3-dimensional representation of electrophoretic fingerprinting. The 2-dimensional treatment has been used to assess the reliability of the data and has detected hysteresis as a possible second-order effect. The 3-dimensional representation has been used to explore the data needed for a reliable overall pattern that characterizes the conditions of pH and conductivity required for an effective microbicide. The dome negative maximum in the electrophoretic fingerprint at high pH, along with the line of zero mobility (LZM) and a dome positive maximum at low pH, are interpreted as evidence for surface carboxyl groups prominent in the alkaline regime and surface amino groups prominent in the acid regime, suggesting that the H9 cell surface is zwitterionic. This has important implications as to the choice and design of microbicide actives.

Microfine zinc oxide is a superior sunscreen ingredient to microfine titanium dioxide.

BACKGROUND: Microfine zinc oxide and microfine titanium dioxide are particulate sunscreen ingredients that absorb broad-spectrum ultraviolet (UV) irradiation. OBJECTIVE: We compare microfine zinc oxide and microfine titanium dioxide for their abilities to attenuate UVA radiation and their relative whiteness in cosmetic formulations. METHODS: UVA attenuation was measured by diffuse reflectance spectroscopy on normal human skin in vivo. Whiteness was determined by reflectance density of dried coatings on a black background of the two particulates at varying concentrations. RESULTS: Microfine zinc oxide demonstrates superior protection compared to microfine titanium dioxide in the UV spectrum between 340 and 380 nm. Microfine zinc oxide is less white than titanium dioxide at all concentrations. CONCLUSION: Microfine zinc oxide is superior to microfine titanium dioxide as a sunscreen ingredient. It is more protective against long-wave UVA and is less white at a given concentration.

Microfine zinc oxide (Z-cote) as a photostable UVA/UVB sunblock agent.

BACKGROUND: Microfine zinc oxide (Z-Cote) is used as a transparent broad-spectrum sunblock to attenuate UV radiation (UVR), including UVA I (340-400 nm). OBJECTIVE: Our purpose was to assess the suitability of microfine zinc oxide as a broad-spectrum photoprotective agent by examining those properties generally considered important in sunscreens: attenuation spectrum, sun protection factor (SPF) contribution, photostability, and photoreactivity. METHODS: Attenuation spectrum was assessed by means of standard spectrophotometric methods. SPF contribution was evaluated according to Food and Drug Administration standards. Photostability was measured in vitro by assessing SPF before and after various doses of UVR. Photoreactivity was evaluated by subjecting a microfine zinc oxide/organic sunscreen formulation to escalating doses of UVR and determining the percentage of organic sunscreen remaining. RESULTS: Microfine zinc oxide attenuates throughout the UVR spectrum, including UVA I. It is photostable and does not react with organic sunscreens under irradiation. CONCLUSION: Microfine zinc oxide is an effective and safe sunblock that provides broad-spectrum UV protection, including protection from long-wavelength UVA.