时下染发已成为时尚。年轻人可以随心所欲改变头发的颜色，配合服饰和妆容，充分显示自己的个性；中老年人不喜欢白发就频繁地染黑。而如果对染发过程和染发产品缺乏了解，很容易会损害头发。这篇文章将带你了解染发剂如何发挥效用，揭秘染发过程。Most hair color products today have nicer smells than the tell-tale rotten-egg odor that once accompanied permanents or hair And most color can be applied easily: some to wet hair， others to dry hair， worked into a shampoo-like lather， left to process and then rinsed（冲洗） and The down side is still that chemicals in hair coloring can be harsh and harmful to your hair if you don't know what you're doing or if you color or perm too How peroxide（过氧化物） and ammonia（氨） react with your hair is directly related to the level and kind of product you're Here are basic descriptions of the three major hair coloring product levels:? Level 1， semi-permanent color -- This product adds color without changing natural color The hair color contains tiny color molecules that enter the hair's cuticle， or outer layer， and go into your hair's cortex（头皮） They don't interact with your natural And since the molecules are small， they eventually exit the hair shaft（发干） after several shampoos， leaving the hair as it was before This level generally lasts for 6 to 12 shampoos， covers up to 50 percent gray， enhances your natural color and leaves no This hair coloring won't lighten your hair color because it contains no ammonia or ? Level 2， demi-permanent color -- This product level lasts longer， through 24 to 26 In this process， pre-color molecules penetrate the cuticle（表层） and enter the cortex（皮层） where they then partner to create medium-sized color Their larger size means they take longer to wash These products do not contain ammonia so the natural pigment can't be However， it contains a small amount of peroxide， which allows for a subtle， but noticeable， color It also blends and covers (Both semi- and demi-permanent colors can become permanent on permed or already-colored hair!)? Level 3， permanent color -- This is what you need for a more significant color change (to go from black to blond， you'll still need to go with a process called double process blonding and it'd be wise to get this it done professionally) In this level， both ammonia and peroxide are Tiny molecules enter all the way into the cortex， where they react and expand to a size that cannot be washed Your hair actually has to grow out over This product acts to lighten the hair's natural pigment to form a new base and then to add a new permanent The end result is a combination of your natural hair pigment and the new shade you That means the color may appear different on you than on someone else using the same Regular touch-ups of 4 to 6 weeks are generally needed to eliminate roots -- hair with your natural color growing at half an inch per month from your scalp（头皮）Now that we've reviewed the different product levels used in hair coloring， let's look at what actually happens to your For example， if you're blonde and are going darker -- to brown -- permanent hair color uses the interaction between the ammonia and the peroxide to create a new color base in your hair If you go in the opposite direction -- from black or brown to blonde -- the hair goes through an additional First， bleach is used to strip the color from the Then the ammonia-peroxide reaction creates the new color and deposits it in the hair If you use a semi-permanent color， the hair is coated with color， rather than deposited into the hair
Abstract Chitosan (Chitosan) and film-forming properties of polyvinyl pyrrolidone (PVP) dissolved outstanding performance， made of composite membrane， through the composite membrane-embedded and glyoxal cross-linking role of the glassy carbon electrode have a common fixed-horseradish dismutase enzymes and hemoglobin (Hb)， Fe (CN) 63-/4- body as an electronic Through cyclic voltammetry study of a variety of electrochemical properties of Experiments prove that the production of this biosensor is simple， selective and sensitive， H2O2 concentration in the linear range of 0 × 10-8 ~ 1 × 10-7 mol / L， the sensor detection limit is 0 × 10-8 mol / L， its The optimum pH of 5， the optimum temperature of 20 ℃ Key words horseradish peroxidase; modified glassy carbon electrode; chitosan; hemoglobin
