For mechanical engineering applications mild steel is used for parts that are not subject to high stress. Depending on the analysis, section and form of supply the tensile strength generally falls in the broad range of 350/550 N/mm. When supplied in the bright cold drawn condition higher figures are obtainable, especially on small diameters.
The Centers for Disease Control and Prevention also issued guidelines about ingesting certain folk medicines which contain a high level of lead and may expose people to lead or lead compounds. For example Daw Tway is a digestive aid used in Thailand and Myanmar (Burma). Analysis of Daw Tway samples showed as much as 970 parts per million (ppm) of lead. The Daw Tway samples also contained high arsenic levels, as high as 7,100 ppm.
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The hippocampus is a part of the brain involved in learning and memory. The main reasons for lead interfering with learning particularly in children is that it damages the cells within the hippocampus. In rats exposed to lead, structural damage such as irregular nuclei and denaturation of myelin were reported (Mycyk et al., 2005).
The treatment for lead poisoning consists of dimercaprol and succimer (Park et al., 2008). Due to the persistent findings on cognitive deficits caused by lead poisoning particularly in children, widespread reduction of exposure should be mandatory.
Since the last published version of this document in 2010 [1], the general approach to categorization has not changed, but several new supplements have been introduced to the market and are subsequently reviewed in this article. In this respect, many supplements have had additional studies published that has led to some supplements being placed into a different category or removed from the review altogether. We understand and expect that some individuals may not agree with our interpretations of the literature or what category we have assigned a particular supplement, but it is important to appreciate that some classifications may change over time as more research becomes available.
While some companies have falsely attributed research on different dietary ingredients or dietary supplements to their own products, suppressed negative research findings, and/or exaggerated results from research studies, the trend in the sports nutrition industry has been to develop scientifically sound supplements. This trend toward greater research support is the result of: (1) attempts to honestly and accurately inform the public about results; (2) efforts to obtain data to support safety and efficacy on products for the FDA and the FTC; and/or, (3) endeavors to provide scientific evidence to support advertising claims and increase sales. While the push for more research is due in part to greater scrutiny from the FDA and FTC, it is also in response to an increasingly competitive marketplace where established safety and efficacy attracts more consumer loyalty and helps ensure a longer lifespan for the product in commerce. Companies that adhere to these ethical standards tend to prosper while those that do not will typically struggle to comply with FDA and FTC guidelines resulting in a loss of consumer confidence and an early demise for the product.
When a powdered formulation is designed, the list of ingredients and raw materials are typically sent to a flavoring house and packaging company to identify the best way to flavor and package the supplement. In the nutrition industry, several main flavoring houses and packaging companies exist who make many dietary supplements for supplement companies. Most reputable dietary supplement manufacturers submit their production facilities to inspection from the FDA and adhere to GMP, which represent industry standards for good manufacturing of dietary supplements. Some companies also submit their products for independent testing by third-party companies to certify that their products meet label claims and that the product is free of various banned ingredients. For example, the certification service offered by NSF International includes product testing, GMP inspections, ongoing monitoring and use of the NSF Mark indicating products comply with inspection standards, and screening for contaminants. More recently, companies have subjected their products for testing by third party companies to inspect for banned or unwanted substances. These types of tests help ensure that the dietary supplement made available to athletes do not contained substances banned by the International Olympic Committee or other athletic governing bodies (e.g., NFL, NCAA, MLB, NHL, etc.). While third-party testing does not guarantee that a supplement is void of banned substances, the likelihood is reduced (e.g., Banned Substances Control Group, Informed Choice, NSF, etc.). Moreover, consumers can request copies of results of these tests and each product that has gone through testing and earned certification can be researched online to help athletes, coaches and support staff understand which products should be considered. In many situations, companies who are not willing to provide copies of test results or certificates of analysis should be viewed with caution, particularly for individuals whose eligibility to participate might be compromised if a tainted product is consumed.
Do the studies report statistically significant results or are claims being made on non-significant means or trends? Appropriate statistical analysis of research results allows for an unbiased interpretation of data. Although studies reporting statistical trends may be of interest and lead researchers to conduct additional research, studies reporting statistically significant results are obviously more convincing. With this said, it is important for people to understand that oftentimes the potential effect a dietary supplement or diet regimen may have above and beyond the effect seen from the exercise bout or an accepted dietary approach is quite small. In addition, many studies examining a biochemical or molecular biology mechanism can require invasive sampling techniques or the study population being recruited is unique (very highly trained) resulting in a small number of study participants. When viewed together, the combination of these two considerations can result in statistical outcomes that do not reach statistical significance even though large mean changes were observed. In these situations, the reporting of confidence intervals on the mean change, individual responses from all participants to the investigated treatment and/or effect sizes are additional pieces of information that can allow for a more accurate interpretation. In all such cases, additional research is warranted to further examine the potential ergogenic aid before conclusions can be made.
Beyond optimal energy intake, consuming adequate amounts of carbohydrate, protein, and fat is important for athletes to optimize their training and performance. In particular and as it relates to exercise performance, the need for optimal carbohydrates before, during and after intense and high-volume bouts of training and competition is evident [41]. Excellent reviews [42, 43] and original investigations [44,45,46,47,48,49] continue to highlight the known dependence on carbohydrates that exists for athletes competing to win various endurance and team sport activities. A complete discussion of the needs of carbohydrates and strategies to deliver optimal carbohydrate and replenish lost muscle and liver glycogen extend beyond the scope of this paper, but the reader is referred to several informative reviews on the topic [23, 41, 50,51,52,53].
As it stands, the need for optimal carbohydrates in the diet for those athletes seeking maximal physical performance is unquestioned. Daily consumption of appropriate amounts of carbohydrate is the first and most important step for any competing athlete. As durations extend into 2 h, the need to deliver carbohydrate goes up, particularly when commencing exercise in a state of fasting or incomplete recovery. Once exercise ceases, several dietary strategies can be considered to maximally replace lost muscle and liver glycogen, particularly if a limited window of recovery exists. In these situations, the first priority should lie with achieving aggressive intakes of carbohydrate while strategies such as ingesting protein with lower carbohydrate amounts, carbohydrate and caffeine co-ingestion or certain forms of carbohydrate may also help to facilitate rapid assimilation of lost glycogen.
Proteins differ based on their source, amino acid profile, and the methods of processing or isolating the protein undergoes [11]. These differences influence the availability of amino acids and peptides, which may possess biological activity (e.g., α-lactalbumin, ß-lactoglobulin, glycomacropeptides, immunoglobulins, lactoperoxidases, lactoferrin, etc.). Additionally, the rate of digestion and/or absorption and metabolic activity of the protein also are important considerations [91]. For example, different types of proteins (e.g., casein, whey, and soy) are digested at different rates, which may affect whole body catabolism and anabolism and acute stimulation of muscle protein synthesis (MPS) [91,92,93,94,95,96]. Therefore, care should be taken not only to make sure the athlete consumes enough protein in their diet but also that the protein is high quality. The best dietary sources of low fat, high quality protein are light skinless chicken, fish, egg whites, very lean cuts of beef and skim milk (casein and whey) while protein supplements routinely contain whey, casein, milk and egg protein. In what is still an emerging area of research, various plant sources of protein have been examined for their ability to stimulate increases in muscle protein synthesis [77, 97] and promote exercise training adaptations [98]. While amino acid absorption from plant proteins is generally slower, leucine from rice protein has been found to be absorbed even faster than from whey [99], while digestive enzymes [100], probiotics [101] and HMB [102] can be used to overcome differences in protein quality. Preliminary findings suggest that rice [98] and pea protein [103] may be able to stimulate similar changes in fat-free mass and strength as whey protein, although the reader should understand that many other factors (dose provided, training status of participants, duration of training and supplementation, etc.) will ultimately impact these outcomes and consequently more research is needed. 2ff7e9595c
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