Saturday, October 15, 2011

DIY Kiwi + Strawberry AHA masque!

A moisturizing skin nourishing face mask may be one of the greatest skin care indulgences available. Unfortunately they are often expensive and full of synthetic perfumes and harsh chemicals. The next time you want to pamperyourself with a skin-rejuvenating facial, forget the beauty aisle at your local grocery store, and head to the produce section. Making your own kiwi facial is fun and easy and less expensive than anything you can buy in a bottle.

Let's get started:

1. Peel one kiwi and place it in the blender or food processor. The seeds of kiwi fruit will help to gently exfoliate the skin, leaving your face smooth and soft. Kiwi, like strawberry, is also full of alpha-hydroxy acid, which can help reduce oil, prevent blackheads and balance your complexion..

2. Place five large strawberries in a blender or small food processor. Strawberries are rich in alpha-hydroxy acid, which gently cleans the skin, reduces acne and eliminates an only shine. Strawberries can also help to eliminate dark circles from under the eyes.

  • 3. Add one half of a peeled cucumber to the food processor or blender. You may want to save two thin slices of cucumber to place over your eyes during your facial, as cucumbers can help to reduce circles under the eyes. Cucumbers contain the same pH as yourskin, so they can clean, nourish and hydrate your skin without stripping it of its natural protective acid layers.

  • 4. Blend the ingredients well and begin to add 1 tsp. of sea kelp at a time until the kiwi face mask reaches a creamy paste-like consistency. Kelp is a natural "vegetable" of the sea and protects and restores damaged skin cells. Kelp is a gentle moisturizer that also reduces sebum production, meaning it will prevent acne and both prevent and reduce wrinkles.

  • 5. Wash yourface with warm water and pat dry. Apply the kiwi face mask to your neck and face with gentle massaging motion to exfoliate your skin. Allow the facial to set for five to 10 minutes before rinsing with cool water and patting dry.


  • How are you feeling now?

    Thursday, October 13, 2011

    Why we age?

    The study of aging - gerontology - is a relatively new science that has made incredible progress over the last 30 years. In the past, scientists looked for a single theory that explained aging. There are two main groups of aging theories. The first group states that aging is natural and programmed into the body, while the second group of aging theories say that aging is a result of damage which is accumulated over time. In the end, aging is a complex interaction of genetics, chemistry, physiology and behavior. 

    Theories of Aging

    By understanding and describing how we age, researchers have developed several different theories of aging. The two categories are: programmed theories and error theories.
    • Programmed Theories assert that the human body is designed to age and there is a certain biological timeline that our bodies follow.
      • Programmed Longevity: Aging is caused by certain genes switching on and off over time.
      • Endocrine Theory: Changes in hormones control aging.
      • Immunological Theory: The immune system is programmed to decline over time, leaving people more susceptible to diseases.
    • Error Theories assert that aging is caused by environmental damage to our body's systems, which accumulates over time.
      • Wear and Tear: Cells and tissues simply wear out.
      • Rates of Living: The faster an organism uses oxygen, the shorter it lives.
      • Cross-Linking: Cross-linked proteins accumulate and slow down body processes.
      • Free Radicals: Free radicals cause damage to cells that eventually impairs function.
      • Somatic DNA Damage: Genetic mutations cause cells to malfunction.

    Genetics and Aging

    Studies have demonstrated that genetics can play a major role in aging. When researchers adjust the genes in certain mice, yeast cells and other organisms, they can almost double the lifespan of these creatures. The meaning of these experiments for people is not known, but researchers think that genetics account for up to 35 percent of the variation in aging among people. Some key concepts in genetics and aging include:
    • Longevity Genes: There are specific genes which help a person live longer.
    • Cell Senescence: The process by which cells deteriorate over time.
    • Telomeres: Structures on the end of DNA that eventually are depleted, resulting in cells ceasing to replicate.
    • Stem Cells: These cells can become any type of cell in the body and hold promise to repair damage caused by aging.

    Biochemistry

    No matter what genes you have inherited, your body is continually undergoing complex biochemical reactions. Some of these reactions cause damage and, ultimately, aging in the body. Studying these complex reactions is helping researchers understand how the body changes as it ages. Important concepts in the biochemistry of aging include:
    • Free Radicals: Unstable oxygen molecules which can damage cells.
    • Protein Cross-Linking: Excess sugars in the blood stream can cause protein molecules to literally stick together.
    • DNA Repair: For an unknown reasons, the systems in the body to repair DNA seem to become less effective in older people.
    • Heat Shock Proteins: These proteins help cells survive stress and are present in fewer numbers in older people.
    • Hormones: The body's hormones change as we age, causing many shifts in organ systems and other functions.

    Body Systems

    As we age, our body's organs and other systems make changes. These changes alter our susceptibility to various diseases. Researchers are just beginning to understand the processes that cause changes over time in our body systems. Understanding these processes is important because many of the effects of aging are first noticed in our body systems. Here is a brief overview of how some body systems age:
    • Heart Aging: The heart muscle thickens with age as a response to the thickening of the arteries. This thicker heart has a lower maximum pumping rate.
    • Immune System Aging: T cells take longer to replenish in older people and their ability to function declines.
    • Arteries and Aging: Arteries usually to stiffen with age, making it more difficult for the heart to pump blood through them.
    • Lung Aging: The maximum capacity of the lungs may decrease as much as 40 percent between ages 20 and 70.
    • Brain Aging: As the brain ages, some of the connections between neurons seem to be reduced or less efficient. This is not yet well understood.
    • Kidney Aging: The kidneys become less efficient at cleaning waste from the body.
    • Bladder Aging: The total capacity of the bladder declines and tissues may atrophy, causing incontinence.
    • Body Fat and Aging: Body fat increases until middle age and then weight typically begins to decrease. The body fat also moves deeper in the body as we age.
    • Muscle Aging: Muscle tone declines about 22 percent by age 70, though exercise can slow this decline.
    • Bone Aging: Starting at age 35, our bones begin to lose density. Walking, running and resistance training can slow this process.
    • Sight and Aging: Starting in the 40s, difficulty seeing close detail may begin.
    • Hearing and Aging: As people age, the ability to hear high frequencies declines.

    Behavioral Factors

    The good news is that many of these causes of aging can be modified through your behaviors:
    • By eating foods loaded with antioxidants, you can minimize damage caused by free radicals.
    • By exercising, you can limit bone and muscle loss.
    • By keeping your cholesterol low, you can slow the hardening of your arteries and protect your heart.
    • By practicing mental fitness, you can keep your brain sharp.
    Lifestyle factors have also been shown to extend life. Rats and mice on a calorie restricted diet (30 percent fewer daily calories) live up to 40 percent longer. Positive thinking has also been shown to extend life in people by up to 7.5 years.
    Source:
    Aging Under the Microscope; National Institutes of Health, National Institute of Aging.

    Monday, September 19, 2011

    Alpha Hydroxy Acids and Chemical Peels


    With increasing research into what causes wrinkles and the effects of photoaging, alpha hydroxy acids have increased greatly in popularity. Alpha hydroxy acids have been used for thousands of years as a skin rejuvenating product. Cleopatra is reported to have bathed in sour mild (lactic acid) to improve her complexion. Now hydroxy acids are a common additive to numerous skin care products including moisturizers, cleanser, toners, and masks.

    Alpha Hydroxy Acids Defined
    Alpha hydroxy acids are derived from fruit and milk sugars. The most commonly used alpha hydroxy acids are glycolic acid and lactic acid because they have a special ability to penetrate the skin. They also have the most scientific data on their effectiveness and side effects. The following are the 5 major types of alpha hydroxy acids found in skin-care products and their sources:

    How Alpha Hydroxy Acids Work
    Alpha hydroxy acids work mainly as an exfoliant. They cause the cells of the epidermis to become "unglued" allowing the dead skin cells to slough off, making room for regrowth of new skin. Alpha hydroxy acids may even stimulate the production of collagen and elastin. Alpha hydroxy acids are reported to improve wrinkling, roughness, and mottled pigmentation of photodamaged skin after months of daily application. Alpha hydroxy acids found in skin-care products work best in a concentration of 5% to 8% and at a pH of 3 to 4.

    Side Effects of Alpha Hydroxy Acids
    The two major side effects of alpha hydroxy acids are irritation and sun sensitivity. Symptoms of irritation include redness, burning, itching, pain, and possibly scarring. People with darker colored skin are at a higher risk of scarring pigment changes with alpha hydroxy acids. The use of alpha hydroxy acids can increase sun sensitivity by 50% causing an interesting dilemma. It appears that alpha hydroxy acids may be able to reverse some of the damage caused by photoaging, but at the same time they make the skin more susceptible to photoaging. It is clear that anyone using alpha hydroxy acids must use a good sunscreen that contains UVA and UVB protection.

    FDA Guidelines on Alpha Hydroxy Acids
    Because of concerns over the side effects of alpha hydroxy acids, the FDA in 1997 announced that alpha hydroxy acids are safe for use by consumers with the following guidelines:


    • The AHA concentration is 10% or less The final product has a pH of 3.5 or higher The final product must have an effective sunscreen in the formulation or warn people to use sunscreen products

    Alpha hydroxy acids in various concentrations are used in chemical peels. The concentration determines who can use it. Alpha hydroxy acid products sold to consumers must have a concentration of less than 10%. Trained cosmetologists can use alpha hydroxy acid products that have a concentration of 20% to 30%. These chemical peels give results that are similar to microdermabrasion - erasing fine lines and giving the skin a smoother appearance with 1 to 3 applications. However, these treatments must be repeated every 3 to 6 months to maintain this skin appearance. Doctors can use alpha hydroxy acid products that have a concentration of 50% to 70%. These treatments also erase fine wrinkles and remove surface scars, but the effects last longer - up to 2 to 5 years. The higher the alpha hydroxy acid concentration used in a chemical peel, the more skin irritation occurs. At the 50% to 70% concentration, a person could expect to have severe redness, flaking, and oozing skin that can last for 1 to 4 weeks.

    The Difference Between Alpha and Beta Hydroxy Acids
    There is only one beta hydroxy acid - salicylic acid. The main difference between alpha hydroxy acids and beta hydroxy acid is their lipid (oil) solubility. Alpha hydroxy acids are water soluble only, while beta hydroxy acid is lipid (oil) soluble. This means that beta hydroxy acid is able to penetrate into the pore which contains sebum and exfoliate the dead skin cells that are built up inside the pore. Because of this difference in properties, beta hydroxy acid is better used on oily skin with blackheads and whiteheads. Alpha hydroxy acids are better used on thickened, sun-damaged skin where breakouts are not a problem.

    Choosing an Alpha Hydroxy Acid
    Alpha hydroxy acids are found in a variety of skin care products including moisturizers, cleansers, eye cream, sunscreen, and foundations. Here are some guidelines to use when trying to decide which alpha hydroxy acid formulation to use: It is best to pick one product that contains the proper formulation of alpha hydroxy acid to use as your exfoliant, and then choose other skin care products or cosmetics that don't contain alpha hydroxy acids to reduce the likelihood of skin irritation. Using an alpha hydroxy acid in a moisturizer base may be the best combination of products. Cleansers containing alpha hydroxy acids are not very effective because the alpha hydroxy acid must be absorbed in the skin to work. Cleansers are washed off before this absorption occurs. At this time there are no effective products that combine alpha hydroxy acid and sunscreen, because sunscreen is not stable at the pH required to make the alpha hydroxy acid effective. Sunscreen MUST be applied liberally when using an alpha hydroxy acid product. The sunscreen should have an SPF of at least 15 for UVB protection and contain avobenzone, titanium dioxide, or zinc oxide for UVA protection. Alpha hydroxy acids work best in a concentration of 5% to 8% and at a pH of 3 to 4. Unfortunately, cosmetic manufacturers are not required to provide concentration information on the label. As a general rule of thumb, having the alpha hydroxy acid listed as the second or third ingredient on the list makes it more likely it contains the proper concentration.

    Thursday, June 30, 2011

    Current Trends in Skin Lightening Ingredients




    Hydroquinone, in the past, was the standard ingredient for skin lightening treatments. Until recently, it was thought to be the safest and most effective treatment for hyperpigmentation, including age spots, melasma, sun damage and other discolorations. However, new research suggests that there may be serious side effects associated with long term use of synthetic hydroquinone. Just recently the FDA also announced its plans to possibly remove hydroquinone based products from store shelves and limit its use to only prescription based medications. Consequently, many manufacturers have begun to produce natural alternatives which mimic the skin lightening properties of hydroquinone. Ingredients such as kojic acid and licorice have become quite popular along with more advanced ingredients like Alpha-Arbutin. When combined, these ingredients can often produce results that even surpass hydroquinone but without the associated risks. Skin lighteners have come a long way in the past few years. With all the available information on the internet, consumers can now educate themselves about the skin bleaching products they buy. This page was designed to help the consumer learn about the many different skin lightening ingredients available on the market today and ultimately choose the best product for his/her skin.

    The process of lightening the skin occurs in several stages. Most of the current skin lightening ingredients on the market work at different stages of the process and typically provide the best results when combined together into one product. Listed below are a few of the more popular ingredients used by manufacturers of skin whitening products.

    Alpha Arbutin:

    Alpha-Arbutin is a biosynthetic active ingredient that is pure, water-soluble and is manufactured in a powder form. As one of the most advanced skin lightening ingredients on the market, it has been shown to work effectively on all skin types. It is the epimer of arbutin, and research has proven that it has a stronger inhibitory action than that of (beta) arbutin. Though it is a very expensive ingredient to manufacture, even at very low concentrations, a-arbutin has shown to inhibit the activity of tyrosinase. Alpha Arbutin's inhibitory mechanism is different from that of arbutin and can be up to 10 times more effective. The a-glucosidic bond found in alpha Arbutin offers higher stability and efficancy than the B form found in the related Beta-Arbutin. This leads to a skin whitening active that acts faster and more efficiently than existing single components.

    Beta-Arbutin (Bearberry Extract):

    Beta-Arbutin is often referred to as just Arbutin. As a natural extract found in bearberry (Uva Ursi) plants, Arbutin also provides a skin lightening effect on the skin by inhibiting tyrosinase activity. Though arbutin is a natural derivative of hydroquinone, it does not possess the same risks or side effects. Arbutin has been shown to be a very safe ingredient and does not break down into hydroquionone very readily. Though it is cheaper to manufacture than Alpha-Arbutin, the skin lightening effect is much less than that of its counterpart. For this reason, many new skin whitening products now use Alpha Arbutin as opposed to only beta-Arbutin.

    Kojic Acid:

    Kojic acid, often used as an ingredient in Asian diets, is a more recent discovery for the treatment of pigmentation problems and age spots. Discovered in 1989, kojic acid is now used extensively as a natural alternative to hydroquinone. Kojic acid is derived from a fungus, and studies have shown that it is effective as a lightening agent, inhibiting production of melanin (brown pigment). Kojic acid is a by-product in the fermentation process of malting rice for use in the manufacturing of sake, the Japanese rice wine. There is convincing research, both in vitro (in a test tube) and in vivo (on a live subject), showing kojic acid to be effective for inhibiting melanin production.

    Licorice Extract:

    The licorice plant serves many purposes in skin care. The ingredient that is responsible for the skin whitening aspect of the plant is known as glabridin. Glabridin inhibits pigmentation by preventing tyrosinase activation. Studies have shown that it can provide a considerable skin brightening effect while remaining non-toxic to the melanin forming cells. Glabridin is found in very small traces and therefore it is important to ensure that the correct part of the licorice plant is used. Licorice's anti-inflammatory properties (due to ihibition of superoxide anion production and cyclooxygenase activity) also make it a very popular ingredient in the skin care industry.
    Niacinamide:

    Niacinamide is commonly known as Vitamin B3 and is an effective skin lightening compound that works by inhibiting melanosome transfer from
    melanocytes to keratinocytes. Often this ingredient works best when combined with other skin lightening treatments. Niacinamide (Vitamin B3) is also known to be effective in reducing acne.

    Mulberry Extract:

    Paper Mulberry extract, is obtained from the root of Broussonetia kazinoki, Siebold. or B. papyrifera, Vent. Tabl. Regn. Veget. or hybrids of both, family Moraceae. Extracts of this root are potent inhibitors of Tyrosinase enzyme. The active constituents present in the extract are Prenylated, polyhydroxylated mono-and bis-phenylderivatives. A 0.4% concentration of paper mulberry extract inhibits tyrosinase by 50% compared to 5.5% for hydroquinone and 10.0% for kojic acid. At 1% paper mulberry extract is not a significant irritant.

    Glycolic Acid:

    Glycolic Acid is a AHA (alpha hydroxy acid) which promotes exfoliation and a natural brightening of the skin tone. By encouraging cell turnover, glycolic acid not only evens out skin discolorations, but also helps to minimize fine lines and wrinkles. AHA's such as Glycolic Acid can assist other ingredients in skin lighteners by allowing them to penetrate farther into the skin.

    Lactic Acid:

    Also an AHA (alpha hydroxy acid), Lactic acid mimics the properties of Glycolic acid but is typically better suited for individuals with sensitive skin. AHA's such as Lacic Acid can assist other ingredients in skin lighteners by allowing them to penetrate farther into the skin.

    Lemon Juice Extract:

    Lemon juice is one of nature's most potent skin bleaching ingredients. Unfortunately it is also very irritating to the skin and should only be used at small concentrations in skin lighteners. Lemon juice is also known to be extremely drying to the skin if applied directly.

    Emblica:

    Emblica is a patented composition extracted from the plant Phyllanthus emblica. The extract uses a multilevel cascade of antioxidant compounds resulting in a long-lasting and stable antioxidant activity. Recent studies have shown that this natural antioxidant also provides significant skin lightening properties when used in moderate concentrations.

    Vitamin C:

    Vitamin C is a natural antioxidant that occurs in many different forms (some stable and others unstable) each with distinct properties. Several of these forms have been shown to reduce melanin formation and provide a skin whitening effect when applied topically. These include l-ascorbic acid, magnesium ascorbyl phosphate and sodium ascorbyl phosphate. These forms when used individually or together can assist in slowing down hyperactive melanocytes and thus resulting in lighter skin.

    Friday, January 28, 2011

    Why the same skin care product can work differently for different user


    Hearing so many opinions on results from the users of the same skin care product, it becomes apparent that we don’t get the same results, even within the same age group and usually, it’s explained on the basis of differences in skin physiology or body chemistry. Additionally, because skin is a dynamic system whose condition and properties depend on various factors, so its ability to absorb the skin care products and react, can vary greatly. Great example of that is the use of a perfume, that often smells entirely different on different people. However, there are products that are developed for all skin types and yet, still don’t work for some. Why is that so and can we try to bring our skin up to par for products to work better on it?

    1. Are you cleaning your skin thoroughly?
    This is the most basic in terms of skin care and yet, some of us are not doing it right. If you’re always using lots of makeup, then it’s important to ensure your face is thoroughly cleanse or even the most expensive skin care product is not going to work so well. So someone who takes time to carefully remove their makeup and cleanse their face thoroughly is definitely going to reap better benefits from using the same products vs one who is nonchalant about this basic step. As a thumb of rule, I really recommend everyone to double cleanse.

    2. Are you having excessive dead skin buildup?
    The dead cells on our skin are supposed to shed naturally over a period of time, but some people may find theirs harder to shed off completely and over time, these result in a buildup, causing one’s skin tone to look ashy and dull. In this case, skin care products may not work as well, especially if they contain active ingredients that are supposed to work beneath the epidermis. As such, those with excessive dead skin buildup will wonder why the cream works for others but not them. Even powder would not adhere that well and will look patchy or cakey. The answer could lie in the fact that they’ve not been exfoliating their skin well enough. Hence, it’s good to exfoliate our skin once a week so as to allow your skin to absorb moisture and for products to work more effectively.

    3. Are you applying your product correctly?
    I noticed that some products these days come with detailed application instructions or even a demo. Some toners are not meant to be wiped on by cotton wool but patted into the skin by hand. Then there are the face sculpting creams where you need to follow a certain method to ensure that you’ll get the desired V-shaped contour. You may also be wondering why the eye cream works better for your friend but perhaps you have not considered that your friend actually took the trouble to tap the cream into the eye area? Even results from a basic moisturizer will differ when you apply it on completely dry skin or slightly damp skin; the latter being encouraged because most ingredients penetrate better when they’re dissolved. And in the past, we might have just spritz on a face mist thinking that it will help to hydrate our skin? Well, that only refreshes but will eventually make your skin feel drier and perhaps secrete more oil and subsequently causing your makeup to streak. The trick is really to spritz and then use a tissue paper to pat off the water and not leave the water to evaporate from the skin.

    4. Are you applying your products at the right time?
    Apart from the moist factor, most skin care products also work better when the skin is warm so the best time to apply skin care products is really after a warm bath. If you’re using products with active ingredients such as vitamin C, then it’s very important to consider the time you’re applying the products. Some of these products may suggest that you can apply it both day and night but that is not true as the benefits of such active ingredients can get “cancelled out” by sun exposure. Hence, you might then start to wonder why the product is not working for you when everyone else is raving about it. Actually in the day, all you need is to apply a moisturizer with SPF. You can leave the serums and hydrating creams for night usage as skin cell renewal rates is really higher at night than during the day. So the mantra should be – protect your skin during the day and renew it during the night.

    5. Are you skipping an important skin care routine?
    One important factor that explains why products work better for others and not you could lie in the fact that you may not be protecting your skin well enough. Perhaps you are not protecting your skin effectively against free radical damage while your girlfriend is taking all the right precautions through her other skin care products as well as her diet? As a result, the product may have to take a longer while to work on your skin while it is already yielding fantastic results on your girlfriend.

    Obviously, there are other reasons contributing to why products may work better on others and those will largely have to do with their lifestyle. However, if you have such a problem, then you may want to first start off by examining your own skin care routine based on the five I’ve listed and find out if you’re doing something wrong to sabotage your own efforts.

    Sunday, January 9, 2011

    WE HAVE A WINNER!


    Our wonderful contest for New Year - New You. Phat QR Solutions Anti Cellulite Collection GIVEAWAY! is now over. Thank you for participation.

    and

    Congratulations to Elena (elena.cacahuete(at)gmail(dot)com) for being a lucky winner.

    We know that giveaways are a lot of fun. So to those who didn't win this time, please keep an eye on our blog, we will have many more contests and giveaways this year.

    Happy New Year to you all!

    Wednesday, December 8, 2010

    New Year - New You. Phat QR Solutions Anti Cellulite Collection GIVEAWAY!


    Every Year we give ourselves New Year resolutions, but who really sticks with them? Hardly anybody we know. So this is not something we are going to do here. We will make it more exciting. We offer one lucky reader to win out best selling Phat QR Solutions Anti Cellulite Collection and pamper herself without setting any resolutions.

    Unfortunately cellulite affects 90 percent of women and 10 percent of men, mostly in industrial nations. As women start approaching menopause, estrogen starts decreasing. From 25 to 35 is when we start seeing the appearance of cellulite. Estrogen has an impact on the blood vessels. When estrogen starts to decrease, we lose receptors in blood vessels and thighs, so we have decreased circulation. With decreased circulation we get less oxygen and nutrition to that area, and with that we see a decrease in collagen production…. At that time fat cells start becoming larger, they begin protruding through the collagen and cellulite starts showing up. Also as we get older we tend to get less active and consume more of the "comfort foods" that usually is full of trans fats and sugars. Cellulite is a collection of stagnant fat cells underneath of skin that needs to be broken down by frequent massaging that improves circulation. Exercise and sensible diet is another "trick" that works, but not all of us like this "trick". We do like a short cut.

    This collection contains everything you might need to assist you in never ending battle with cellulite. Phat QR Massager improves circulation, seaweed scrub helps to draw out toxins while polishing your skin and NuElle contains a cocktail of 25 well known flub busters that assist in weight loss and cellulite reduction, like caffeine, L'Carnitine, Butcher's Broom, Bladderwrack, Ivy and many others. Formulated to work both on the surface and in depth, this revolutionary treatment has multiple performance that can be seen with the naked eye within 3-4 weeks (results may vary). Firming on the surface, detoxifying on the inside, reducing water retention and fat cell clusters, while improving circulation and overall appearance of the skin.

    Giveaway rules:

    1. All the entrants have to visit our site www.skinqr.com and let us know what other product, not related to this collection, they would like to own. (this entry is mandatory)
    2. Follow us on this Blog
    3. Like us on Facebook
    4. Follow us on Twitter
    5. Blog about this giveaway and insert the link
    6. Twit about this giveaway and post the link (can do this every day)
    7. Post this giveaway on your Blog (and give us link)
    8. Purchasing something from our site would give you 5 extra entries. (mention what it is)

    Please don't forget to make a separate post for every activity you do.

    This giveaway is open to US residents only. Winner will be chosen on December 30th, 2010 randomly through www.randon.org.
    Winner has 24 hours to respond to our notification, otherwise a different winner will be chosen.

    Good Luck