Circadian rhythms in axillary skin surface pH

Sweat and skin surface pH are critical parameters in determining the performance of antiperspirants. The mechanism of action, the so-called 'plug theory' first proposed by Reller and Luedders, involves the expression of eccrine sweat onto the surface of the skin into which the solid antiperspirant salts, typically an aluminium chlorohydrate or zirconium aluminium glycine, dissolve. The resultant acidic 'solution' then diffuses with time into the sweat glands, where it hydrolyses in more alkaline sweat and forms an amorphous metal hydroxide agglomerate that physically plugs the ducts some 20-100 mum into the glands. It is therefore important to understand whether diurnal variations in skin surface pH exist in the axilla, as these may influence strongly the time of day at which antiperspirant should be applied in order to yield maximal protection. Clinical studies demonstrate a significant fall in axillary skin surface pH between the morning (pH = 5.87 +/- 0.23) and the evening (pH = 5.49 +/- 0.23). This diurnal variation in skin surface pH suggests that antiperspirant efficacy will be optimal when products are applied in the morning. In addition, the data suggest a circadian rhythm in axillary skin barrier function, indicating that chronopharmacology, the timing of administration of medication, could be used to optimize treatment of axillary hyperhidrotics using topical administration of anticholinergic drugs.     

Erroneous gender differences in axillary skin surface/sweat pH

Assessing accurately the pH of axillary eccrine sweat is of vital importance in the antiperspirant industry. Eccrine sweat pH is a critical parameter in determining the effectiveness of antiperspirants; antiperspirant salts dissolve in sweat and diffuse into the sweat glands, where the resultant acidic solution hydrolyses in more alkaline sweat forming an amorphous metal hydroxide gel, thereby restricting the flow of eccrine sweat. Comparison of the skin surface and sweat pH of males and females reported in the literature shows that, although consistent male/female differences have been observed on the forearm, determination of significant gender-based pH differences across other sites are less conclusive. Studies on the back and infra-mammary regions exhibited significant gender differences in skin surface pH, whereas those on the forehead, cheek, neck and inguinal area showed no such difference. With regard to the axilla specifically, four studies have been reported, three showing no significant difference in axillary skin surface pH and one indicating that females have an eccrine sweat pH of 7 and males have a sweat pH of 5.6. This paper describes a series of carefully controlled studies aimed at assessing potential gender differences in eccrine sweat and skin surface pH following exposure to a variety of temperature, humidity and time conditions. The results highlight the importance of controlling precisely the time of investigation, site of measurement and, most importantly, the necessity to pre-equilibrate samples in 40 mmHg carbon dioxide (equivalent to arterial CO(2) tension (pCO2)) before determining sweat pH. When these parameters are controlled no gender differences in axillary sweat or skin surface pH are observed. Large differences in eccrine sweat and skin surface pH are found, however, between the vault (hairy region) and fossa (non-hairy region) of the axilla.     

The effects of pH and surface composition on Pb adsorption to natural freshwater biofilms

Two dominant variables that control the adsorption of toxic trace metals to suspended particulate materials and aquatic surface coatings are surface composition and solution pH. A model for the pH-dependent adsorption of Pbto heterogeneous particulate surface mixtures was derived from experimental evaluation of Pb adsorption to laboratory-derived surrogates. The surrogate materials were selected to represent natural reactive surface components. Pb adsorption to both the laboratory surrogates and natural biofilms was determined in chemically defined solutions under controlled laboratory conditions. Pb adsorption was measured over a pH range of 5-8, with an initial Pb concentration in solution of 2.0 microM. The surface components considered include amorphous Fe oxide, biogenic Mn oxide produced by a Mn(II) oxidizing bacterium (Leptothrix discophora SS-1), Al oxide, the common green alga Chlorella vulgaris, and Leptothrix discophora SS-1 cells. A linearization of Pb adsorption data for each adsorbent was used to quantify the relationship between Pb adsorption and pH. The parameters for individual adsorbents were incorporated into an additive model to predict the total Pb adsorption in multiple-adsorbent natural surface coatings that were collected from Cayuga Lake, NY. Pb adsorption experiments on the natural surface coatings at variable pH were utilized to verify the additive model predictions based on the pH dependent behavior of the experimental laboratory surrogates. Observed Pb adsorption is consistent with the model predictions (within 1-24%) over the range of solution pH values considered. The experimental results indicate that the combination of Fe and biogenic Mn oxides can contribute as much as 90% of Pb adsorbed on Cayuga Lake biofilms, with the dominant adsorbent switching from Mn to Fe oxide with increasing pH.     

Effect of thyroidin on the indices of intraduodenal pH measurement

Intraduodenal pHgraphy was used in experiments on thyroidine fed dogs with duodenal fistulas to study the time course of pH modulations without regard for, and during digestion. A decrease in the duodenal pH and occurrence of pH-waves on an empty stomach were recorded. After feeding the animals pH-waves disappeared and then recurred. They were arrhythmic in nature and unsteady in amplitude. The changes in the duodenal pH seen after thyroidine intake might be related to the processes of continuous acid output in the stomach induced by thyroid hormones and rapid evacuation of the acidic contents from the stomach to the duodenum.     

Natural skin surface pH is on average below 5, which is beneficial for its resident flora

Variable skin pH values are being reported in literature, all in the acidic range but with a broad range from pH 4.0 to 7.0. In a multicentre study (N = 330), we have assessed the skin surface pH of the volar forearm before and after refraining from showering and cosmetic product application for 24 h. The average pH dropped from 5.12 +/- 0.56 to 4.93 +/- 0.45. On the basis of this pH drop, it is estimated that the 'natural' skin surface pH is on average 4.7, i.e. below 5. This is in line with existing literature, where a relatively large number of reports (c. 50%) actually describes pH values below 5.0; this is in contrast to the general assumption, that skin surface pH is on average between 5.0 and 6.0. Not only prior use of cosmetic products, especially soaps, have profound influence on skin surface pH, but the use of plain tap water, in Europe with a pH value generally around 8.0, will increase skin pH up to 6 h after application before returning to its 'natural' value of on average below 5.0. It is demonstrated that skin with pH values below 5.0 is in a better condition than skin with pH values above 5.0, as shown by measuring the biophysical parameters of barrier function, moisturization and scaling. The effect of pH on adhesion of resident skin microflora was also assessed; an acid skin pH (4-4.5) keeps the resident bacterial flora attached to the skin, whereas an alkaline pH (8-9) promotes the dispersal from the skin.     

A fully automated system to study skin surface patterns

An image analysis method to measure the human skin microrelief has been previously proposed.
This new method has been recently automated, using a 'robot'electronically driven by a Quantimet 900. This 'robot'consists of a change-over specimen driven by four motors, and allows forty Silflo® replicas to be analysed in 6 hours, each analysis giving the main directions of the furrows, their density and their mean depth.
For example, the volar forearm microrelief was studied from the detected shadows created by a 26° angle lighting, in the range of 5 to 100 μ m deep furrows. A 38° angle lighting allows such measurements from 50 to 1000 μ m and is used for studying 'crow's feet'wrinkles of the face.
Results clearly show that deep wrinkles appear as early as 30 years old on the human face. The consequences of actinic and mechanical stresses over the life span are discussed.
Un système automatique pour l'étude du relief cutané chez l'homme     

Influence of skin cleansing preparation acidity on skin surface properties

Two long-term trials were conducted each over eight weeks to compare the effect of the regular application of skin cleansing preparations of pH 5.5 and pH 8.5 and pH 5.5 and pH 7.0 respectively on the surface pH, roughness and transepidermal water loss (TEWL) of normal human forehead and forearm skin. Both trials were based on a cross-over design: five healthy volunteers started with a pH 5.5 preparation and switched to the other after four weeks, five additional volunteers used the preparations in the opposite order. While the skin surface pH was markedly lower in those individuals using the pH 5.5 preparation at each examination, as compared to those using the pH 8.5 or pH 7.0 preparation, no such difference could be established with respect to skin roughness and TEWL. Hence the skin irritancy of a cleansing preparation does not seem to be linked to its pH within the pH ranges tested.     

火龙果果皮色素提取工艺研究

火龙果果皮色素是从火龙果果品加工副产物果皮中提取的天然色素,具有“天然、营养、多功能”等多重优点,故作为添加剂在食品加工业、化妆品制造业等中都具有很好的应用前景.本实验拟实现火龙果的综合利用,提高火龙果的附加值,拓展其应用范围,研究了从火龙果果皮中提取红色素的工艺条件.选用火龙果果皮为原料,对火龙果果皮内红色素采用溶剂浸提法进行提取,研究材料的储存方法、浸提液种类、液料比、浸提时间、浸提温度以及pH对色素提取的影响,确定最适的工艺条件:对火龙果果皮进行冷冻储存;浸提液为去离子水;液料比为5∶1;浸提时间30min;浸提温度50℃;浸提液pH6时,可以得到高产率、高色值、安全的火龙果果皮红色素.     

天然产物的美白作用及其机理研究进展

天然产物化妆品顺应了回归大自然的发展潮流和人们的消费需求,将成为化妆品开发中的主题。从黑色素的形成过程及在皮肤中的分布,美白机理,植物源、动物源等天然产物作为美白剂三方面进行了综述,并提出了未来天然产物作为美白剂的研究重点和发展趋势。     

金刚石表面镀钛层的X射线衍射测量

对表面有镀铁层的金刚石晶体进行了射线衍射测量,得到了金刚石晶体表面有金属化合物形成的结果。同时,得到了一个较有疑问的X射线衍射峰,文章尝试进行一些分析。     

The effect of smoking on skin moisture and on surface lipids

In the present retrospective study we investigated the effect of smoking on the moisture and surface lipid levels of the skin. We analysed data from the files of 576 female clients treated in a Tel-Aviv cosmetic parlour. Measurements have been conducted by the same cosmetician, by commercially available equipment, on every client receiving cosmetic treatment, regardless of the nature of the treatment.
Results demonstrated a significant difference of skin moisture in the various smoking groups: women who smoked 11–20 cigarettes per day showed significantly lower mean values than the non-smoker group, as expected. Moreover, women before or after menopause showed no significant differences in their moisture measurements.
The surface lipid variables showed no significant differences in mean over the four smoking groups.
We believe that the objective of the study was achieved, and that the results, indicating decreased skin moisture in smokers, will serve well in anti-smoking campaigns. We also believe that the present study will stimulate other investigators to conduct similar studies that will provide answers to the many questions which still remain open.     

健康肌肤自然红

很多人都存在着这样的情况：皮肤很白嫩细腻．只是这白嫩细腻下透着的不是均匀的粉红．而是一根根清晰可见的红红的细小血丝。不要以为这就是所谓的“健康红”．这种因细小血丝而来的“红”是面部的毛细血管扩张所引起的一种皮肤疾病。现代医学认为．由于体内维生素C缺乏．胶原性疾病．以及植物神经、内分泌功能紊乱等．致使面部角质层变薄，毛细血管通透性增强，血管迂回、扩张，血液汇聚．以致皮下血管清晰可见。[编者按]     

葡萄皮天然保健饮料的研制

探讨了以葡萄皮为原料生产天然保健饮料的最适配比和工艺流程。结果表明 ,该饮料不仅具有良好的风味 ,还具有一定的营养价值和保健功能。     

Development of quantitative analysis for the micro-relief of the skin surface using a video microscope and its application to examination of skin surface texture

We developed a new analyzing method for characterizing a skin surface morphology image obtained easily by a video microscope. For the numerical analysis of various characteristics of the skin surface morphology, three parameters were invented; 'the width of the skin furrows,'the fineness of the skin ridges,' and 'the size of the skin pores.' The width of the skin furrows was calculated as mean width of the skin furrows. The fineness of the skin ridges was calculated as number of the skin ridges. The size of the skin pores was calculated as total area of skin pores. The analyzed parameters were compared with the clinical scores evaluated by trained experts, resulting in a high correlation (r = 0.54–0.72). Upon the age related changes in the parameters described above, the number of the skin ridges decreased at around the age of 20, and the size of the skin pores became large with aging during the teens through 40's. In the analysis of seasonal changes, the ridge parameter was high in summer, and the furrow parameter was high in winter. Upon the relationship between the images (the skin surface patterns) and the skin physiological parameters, the skin with a low barrier function (high TEWL) or that with high sebum content gave a low density of the skin ridges. From these results it seems that the image analysis of skin surface morphology using a video microscope is quite useful for an easy and simple evaluation of skin condition.     

木材表面立体自然纹理加工设备的初步设计

为了使速生人工林木材表面具有凹凸自然纹理,设计了一种应用刷削机构加工的设备.     

葡萄皮红色素的示差法测定

用1%HCl-乙醇对葡萄皮中的红色素进行了提取,经紫外、可见光谱,化学分析方法初步确定葡萄皮红色素为花青素,并用pH示差法对葡萄皮中的花青素含量进行了分析,结果表明葡萄皮中花青素含量在0.2%～0.3%,这一含量具有开发价值。     

天然色素和人工色素对肉仔鸡皮肤和脚胫颜色影响的研究

研究在日粮中添加含天然色素的玉米和人工色素的加丽素红对AA肉仔鸡皮肤和脚胫颜色的影响。结果表明:AA肉仔鸡饲喂含天然色素的玉米和含人工色素的加丽素红的日粮都能改善AA肉仔鸡皮肤、脚胫颜色。人工色素组,随着加丽素红添加量的提高,各处理的RCF值提高,30mg/kg、60mg/kg组RCF值较对照组提高显著(P<0.05)。天然色素组,试验前期随着玉米添加量的提高,各处理的RCF值提高,50%、70%玉米组较对照组提高显著(P<0.05)。人工色素组加丽素红添加量为60mg/kg时,AA肉仔鸡皮肤和脚胫的RCF值与天然色素组日粮中玉米添加量为50%的着色程度一致。试验后期,人工色素组玉米添加量均为30%的处理1、处理2与天然色素组玉米添加量为30%的处理6AA肉仔鸡皮肤和脚胫的RCF值保持一致。     

天然深加工食品开发和食品“天然度”的检测

天然深加工食品是指符合该类食品的过程控制和产品安全标准,农产品原料符合无公害食品标准,不添加有机合成物质,天然度≥99.3%的食品。阐述建立天然深加工食品生产监管体系的意义,提出基于同位素技术的食品"天然度"的检测方法,并论述天然食品添加剂和天然深加工食品的开发途径。     

信阳毛尖茶汤pH值的初步研究

对不同信阳毛尖茶汤的pH进行了测定,结果表明,茶汤的pH值在一定程度上能反映出茶叶质量的高低,不同嫩度的茶叶酸碱度不同。芽茶酸性相对比叶茶弱,即茶叶越嫩,酸性越弱,茶叶越老,酸性越强。并对高档信阳毛尖与低档信阳毛尖茶汤的pH值比较,结果显示,茶汤的pH值随茶叶品质的下降而下降,这是由于嫩度越差,茶叶有机酸含量越多。     

In vivo measurement of the surface energy of human fingernail plates

The surface energy of the human nail plate is expected to influence the adhesion of microorganisms (and subsequent colonization and infections) as well as that of medicines (and subsequent drug permeation) and of cosmetics. The aim of the study was therefore to measure the surface energy of nail plates in vivo. The surface energy of healthy human fingernails (untreated, hydrated and abraded) and of hoof membranes (often used as a model for the nail plate) was estimated from contact angle measurements of liquids (water, formamide, diiodomethane and glycerol) on the nail plate and subsequent computation using the Lifshitz-van der Waals/acid-base (LW-AB) approach. The surface energy of untreated fingernail plates was found to be 34 mJ m(-2) . Most of this total energy was from the apolar Lifshitz-van der Waals component. When the polar component of the surface energy was analysed, the electron donor component was considerably larger than the electron acceptor one. Hydrating the nail plate had no significant influence on the surface energy. In contrast, abrasion caused a small, but statistically significant increase in the apolar surface energy component. The surface energy of bovine hoof membrane was similar to that of the fingernail plate. We conclude that the human fingernail plate is a low-energy surface and that bovine hoof membranes may be used as a substitute for the nail plate in certain experiments.