European Chemicals Agency
The European Chemicals Agency is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation and Restriction of Chemicals. ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern, it is located in Finland. The agency headed by Executive Director Bjorn Hansen, started working on 1 June 2007; the REACH Regulation requires companies to provide information on the hazards and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most used substances have been registered; the information is technical but gives detail on the impact of each chemical on people and the environment.
This gives European consumers the right to ask retailers whether the goods they buy contain dangerous substances. The Classification and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU; this worldwide system makes it easier for workers and consumers to know the effects of chemicals and how to use products safely because the labels on products are now the same throughout the world. Companies need to notify ECHA of the labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100 000 substances; the information is available on their website. Consumers can check chemicals in the products. Biocidal products include, for example, insect disinfectants used in hospitals; the Biocidal Products Regulation ensures that there is enough information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation; the law on Prior Informed Consent sets guidelines for the import of hazardous chemicals.
Through this mechanism, countries due to receive hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have serious effects on human health and the environment are identified as Substances of Very High Concern 1; these are substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment and do not break down. Other substances considered. Companies manufacturing or importing articles containing these substances in a concentration above 0,1% weight of the article, have legal obligations, they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy. Once a substance has been identified in the EU as being of high concern, it will be added to a list; this list is available on ECHA's website and shows consumers and industry which chemicals are identified as SVHCs.
Substances placed on the Candidate List can move to another list. This means that, after a given date, companies will not be allowed to place the substance on the market or to use it, unless they have been given prior authorisation to do so by ECHA. One of the main aims of this listing process is to phase out SVHCs where possible. In its 2018 substance evaluation progress report, ECHA said chemical companies failed to provide “important safety information” in nearly three quarters of cases checked that year. "The numbers show a similar picture to previous years" the report said. The agency noted that member states need to develop risk management measures to control unsafe commercial use of chemicals in 71% of the substances checked. Executive Director Bjorn Hansen called non-compliance with REACH a "worry". Industry group CEFIC acknowledged the problem; the European Environmental Bureau called for faster enforcement to minimise chemical exposure. European Chemicals Bureau Official website
Scanning tunneling microscope
A scanning tunneling microscope is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer, the Nobel Prize in Physics in 1986. For an STM, good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm depth resolution. With this resolution, individual atoms within materials are imaged and manipulated; the STM can be used not only in ultra-high vacuum but in air and various other liquid or gas ambients, at temperatures ranging from near zero kelvin to over 1000 °C. STM is based on the concept of quantum tunneling; when a conducting tip is brought near to the surface to be examined, a bias applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, the local density of states of the sample. Information is acquired by monitoring the current as the tip's position scans across the surface, is displayed in image form.
STM can be a challenging technique, as it requires clean and stable surfaces, sharp tips, excellent vibration control, sophisticated electronics, but nonetheless many hobbyists have built their own. First, a voltage bias is applied and the tip is brought close to the sample by coarse sample-to-tip control, turned off when the tip and sample are sufficiently close. At close range, fine control of the tip in all three dimensions when near the sample is piezoelectric, maintaining tip-sample separation W in the 4-7 Å range, the equilibrium position between attractive and repulsive interactions. In this situation, the voltage bias will cause electrons to tunnel between the tip and sample, creating a current that can be measured. Once tunneling is established, the tip's bias and position with respect to the sample can be varied and data are obtained from the resulting changes in current. If the tip is moved across the sample in the x-y plane, the changes in surface height and density of states causes changes in current.
These changes are mapped in images. This change in current with respect to position can be measured itself, or the height, z, of the tip corresponding to a constant current can be measured; these two modes are called constant current mode, respectively. In constant current mode, feedback electronics adjust the height by a voltage to the piezoelectric height control mechanism; this leads to a height variation and thus the image comes from the tip topography across the sample and gives a constant charge density surface. In constant height mode, the voltage and height are both held constant while the current changes to keep the voltage from changing; the benefit to using a constant height mode is that it is faster, as the piezoelectric movements require more time to register the height change in constant current mode than the current change in constant height mode. All images produced by STM are grayscale, with color optionally added in post-processing in order to visually emphasize important features.
In addition to scanning across the sample, information on the electronic structure at a given location in the sample can be obtained by sweeping voltage and measuring current at a specific location. This type of measurement is called scanning tunneling spectroscopy and results in a plot of the local density of states as a function of energy within the sample; the advantage of STM over other measurements of the density of states lies in its ability to make local measurements: for example, the density of states at an impurity site can be compared to the density of states far from impurities. Framerates of at least 25 Hz enable so called video-rate STM. Framerates up to 80 Hz are possible with working feedback that adjusts the height of the tip. Due to the line-by-line scanning motion, a proper comparison on the speed requires not only the framerate, but the number of pixels in an image: with a framerate of 10 Hz and 100x100 pixels the tip moves with a line frequency of 1 kHz, whereas it moves with only with 500 Hz, when measuring with a faster framerate of 50 Hz but only 10x10 pixels.
Video-rate STM can be used to scan surface diffusion. The components of an STM include scanning tip, piezoelectric controlled height and x,y scanner, coarse sample-to-tip control, vibration isolation system, computer; the resolution of an image is limited by the radius of curvature of the scanning tip of the STM. Additionally, image artifacts can occur if the tip has two tips at the end rather than a single atom. Therefore, it has been essential to develop processes for obtaining sharp, usable tips. Carbon nanotubes have been used in this instance; the tip is made of tungsten or platinum-iridium, though gold is used. Tungsten tips are made by electrochemical etching, platinum-iridium tips by mechanical shearing. Due to the extreme sensitivity of tunnel current to height, proper vibration insulation or an rigid STM body is imperative for obtaining usable results. In the first STM by Binnig and Rohrer, magnetic levitation was used to keep the STM free from vibrations. Additionally, mechanisms for reducing eddy currents are sometimes implemented.
Maintaining the tip position with respect to the sample, scanning the
Perylene or perilene is a polycyclic aromatic hydrocarbon with the chemical formula C20H12, occurring as a brown solid. It or its derivatives may be carcinogenic, it is considered to be a hazardous pollutant. In cell membrane cytochemistry, perylene is used as a fluorescent lipid probe, it is the parent compound of a class of rylene dyes. Perylene displays blue fluorescence, it is pure or substituted. Perylene can be used as an organic photoconductor, it has an absorption maximum at 434 nm, as with all polycyclic aromatic compounds, low water solubility. Perylene has a molar absorptivity of 38,500 M−1cm−1 at 435.7 nm. The perylene molecule consists of two naphthalene molecules connected by a carbon-carbon bond at the 1 and 8 positions on both molecules. All of the carbon atoms in perylene are sp2 hybridized; the structure of perylene has been extensively studied by X-ray crystallography. Occurring perylene quinones have been identified in lichens Laurera sanguinaria Malme and Graphis haematites Fée
Katazome is a Japanese method of dyeing fabrics using a resist paste applied through a stencil. With this kind of resist dyeing, a rice flour mixture is applied using a brush or a tool such as a palette knife. Pigment is added by immersion or both. Where the paste mixture covers and permeates the cloth, dye applied will not penetrate. Katazome on thin fabrics shows a pattern through to the back. Futon covers made from multiple panels of fabric, if the stencils are properly placed and the panels joined exhibit a pleasing over-all pattern in addition to the elements cut into the stencil. One attraction of katazome was that it provided an inexpensive way for over-all patterns similar to expensive woven brocades to be achieved on cotton; as with many everyday crafts of Japan it developed into a respected art form of its own. Besides cotton, katazome has been used to decorate linen and fabrics that are all or synthetic. Shibori, another Japanese method of resist dyeing. Serizawa Keisuke Mika Toba What is Katazome?
Paste Resist Recipe About Katazome Katazome
Batik is a technique of wax-resist dyeing applied to whole cloth, or cloth made using this technique, originated from Indonesia, Batik is made either by drawing dots and lines of the resist with a spouted tool called a tjanting, or by printing the resist with a copper stamp called a cap. The applied wax resists dyes and therefore allows the artisan to colour selectively by soaking the cloth in one colour, removing the wax with boiling water, repeating if multiple colours are desired. A tradition of making batik is found in various countries. Indonesian batik made in the island of Java has a long history of acculturation, with diverse patterns influenced by a variety of cultures, is the most developed in terms of pattern and the quality of workmanship. In October 2009, UNESCO designated Indonesian batik as a Masterpiece of Oral and Intangible Heritage of Humanity; the word batik is Javanese in origin. It may either come from the Javanese word amba and titik, or may derive from a hypothetical Proto-Austronesian root *beCík.
The word is first recorded in English in the Encyclopædia Britannica of 1880, in which it is spelled battik. It is attested in the Indonesian Archipelago during the Dutch colonial period in various forms: mbatek, mbatik and batik. Wax resist, it existed in Egypt in the 4th century BC, where it was used to wrap mummies. In Asia, the technique was practised in China during the Tang Dynasty, in India and Japan during the Nara Period. In Africa it was practised by the Yoruba tribe in Nigeria and Wolof in Senegal; these African version however, uses cassava starch or rice paste, or mud as a resist instead of beeswax. The art of batik is most developed in the island of Java in Indonesia. In Java, all the materials for the process are available — cotton and beeswax and plants from which different vegetable dyes are made. Indonesian batik predates written records: G. P. Rouffaer argues that the technique might have been introduced during the 6th or 7th century from India or Sri Lanka. On the other hand, the Dutch archaeologist J.
L. A. Brandes and the Indonesian archaeologist F. A. Sutjipto believe Indonesian batik is a native tradition, since other regions in Indonesia such as Toraja, Flores and Papua, which were not directly influenced by Hinduism, have an age-old tradition of batik making. Rouffaer reported that the gringsing pattern was known by the 12th century in Kediri, East Java, he concluded that this delicate pattern could be created only by using the canting, an etching tool that holds a small reservoir of hot wax, proposed that the canting was invented in Java around that time. The carving details of clothes worn by East Javanese Prajnaparamita statues from around the 13th century show intricate floral patterns within rounded margins, similar to today's traditional Javanese jlamprang or ceplok batik motif; the motif is thought to represent a sacred flower in Hindu-Buddhist beliefs. This evidence suggests that intricate batik fabric patterns applied with the canting existed in 13th-century Java or earlier. In Europe, the technique was described for the first time in the History of Java, published in London in 1817 by Stamford Raffles, a British governor for Bengkulu, Sumatra.
In 1873 the Dutch merchant Van Rijckevorsel gave the pieces he collected during a trip to Indonesia to the ethnographic museum in Rotterdam. Today the Tropenmuseum houses the biggest collection of Indonesian batik in the Netherlands; the Dutch and Chinese colonists were active in developing batik coastal batik, in the late colonial era. They introduced new patterns as well as the use of the cap to mass-produce batiks. Displayed at the Exposition Universelle at Paris in 1900, the Indonesian batik impressed the public and artists. In the 1920s, Javanese batik makers migrating to Malaya introduced the use of wax and copper blocks to its east coast. In Subsaharan Africa, Javanese batik was introduced in the 19th century by Dutch and English traders; the local people there adapted the Javanese batik, making larger motifs with thicker lines and more colours. In the 1970s, batik was introduced to Australia, where aboriginal artists at Erna Bella have developed it as their own craft. Firstly, a cloth is washed and beaten with a large mallet.
Patterns are drawn with pencil and redrawn using hot wax made from a mixture of paraffin or beeswax, sometimes mixed with plant resins, which functions as a dye-resist. The wax can be applied with a variety of tools. A pen-like instrument called. A tjanting is made from a small copper reservoir with a spout on a wooden handle; the reservoir holds the resist which flows through the spout, creating lines as it moves. For larger patterns, a stiff brush may be used. Alternatively, a copper block stamp called. After the cloth is dry, the resist is removed by scraping the cloth; the areas treated with resist keep their original colour. This process is repeated as many times; the most traditional type of batik, called batik tulis, is drawn using only the canting. The cloth needs to be drawn on both sides, dipped in a dye bath three to four times; the whole process may take up to a year.
Ikat is a dyeing technique used to pattern textiles that employs resist dyeing on the yarns prior to dyeing and weaving the fabric. In ikat the resist is formed by binding individual yarns or bundles of yarns with a tight wrapping applied in the desired pattern; the yarns are dyed. The bindings may be altered to create a new pattern and the yarns dyed again with another colour; this process may be repeated multiple times to produce multicolored patterns. When the dyeing is finished all the bindings are removed and the yarns are woven into cloth. In other resist-dyeing techniques such as tie-dye and batik the resist is applied to the woven cloth, whereas in ikat the resist is applied to the yarns before they are woven into cloth; because the surface design is created in the yarns rather than on the finished cloth, in ikat both fabric faces are patterned. A characteristic of ikat textiles is an apparent "blurriness" to the design; the blurriness is a result of the extreme difficulty the weaver has lining up the dyed yarns so that the pattern comes out in the finished cloth.
The blurriness can be reduced by the skill of the craftsperson. Ikats with little blurriness, multiple colours and complicated patterns are more difficult to create and therefore more expensive. However, the blurriness, so characteristic of ikat is prized by textile collectors. Ikat is produced in many traditional textile centres around the world, from India to Central Asia, Southeast Asia, Japan and Latin America. Double ikats—in which both the warp and weft yarns are tied and dyed before being woven into a single textile—are rare because of the intensive skilled labour required to produce them, they are produced in Okinawa islands of Japan, the village of Tenganan in Indonesia, the villages of Puttapaka and Bhoodan Pochampally in Telangana in India. In fact, many other parts of India have their indigenous Ikat weaving techniques. Orissa’s Sambalpuri Ikat is quite different from the sharp Ikat patterns, woven in Patan of Gujarat; the latter, known as Patan Patola, is one of the rarest forms of double Ikat, which takes a lot of time and effort in dyeing and weaving.
A different form of Patola ikat is made in Gujarat. Telia Rumal made in Andhra, Pasapalli from Odisha and Puttapaka from Telangana are other Indian Ikats. In warp ikat it is only the warp yarns; the weft yarns are dyed a solid colour. The ikat pattern is visible in the warp yarns wound onto the loom before the weft is woven in. Warp ikat is, amongst others, produced in Indonesia. In weft ikat it is the weft yarn that carries the dyed patterns. Therefore, the pattern only appears as the weaving proceeds. Weft ikats are much slower to weave than warp ikat because the weft yarns must be adjusted after each passing of the shuttle to maintain the clarity of the design. Double Ikat is a technique in which the weft are resist-dyed prior to weaving, it is the most difficult to make and the most expensive. Double ikat is only produced in three countries: India and Indonesia; the double ikat made in Patan, Gujarat in India is the most complicated. Called "patola," it is made using many colours, it may be patterned with a small motif, repeated many times across the length of a six-meter sari.
Sometimes the Patan double ikat is pictorial with no repeats across its length. That is, each small design element in each colour was individually tied in the warp and weft yarns. It's an extraordinary achievement in the textile arts; these much sought after textiles were traded by the Dutch East Indies company for exclusive spice trading rights with the sultanates of Indonesia. The double ikat woven in the small Bali Aga village, Tenganan in east Bali in Indonesia reflects the influence of these prized textiles; some of the Tenganan double ikat motifs are taken directly from the patola tradition. In India double ikat is woven in Puttapaka, Nalgonda District and is called Puttapaka Saree. In Japan, double ikat is woven in the Okinawa islands. Pasapalli Ikat is one of the Ikkat saree and Pasapalli ikat saree made in Odisha; the word Pasapalli comes from ` Pasa'. Each pasapalli ikat saree or material -, made with the same technique as the Sambalpuri Ikat - has some or the other form of this chequered design.
Ikat is an Indonesian language word, which depending on context, can be the nouns: cord, thread and the finished ikat fabric as well as the verbs "to tie" or "to bind". It has a direct etymological relation to Javanese language of the same word. Thus, the name of the finished ikat woven fabric originates from the tali being ikat before they are being put in celupan berjalin resulting in a berjalin ikat- reduced to ikat; the introduction of the term ikat into European language is attributed to Rouffaer. Ikat is now a generic English loanword used to describe the process and the cloth itself regardless of where the fabric was produced or how it is patterned. In Indonesian the plural of ikat remains ikat. However, in English a suffix plural's' is added, as in ikats; this is true in other some other languages. All are correct. Ikat is a weaving style common to many world cultures, it is one of the oldest forms of textile decoration. However, it is most prevalent in Indonesia and Japan. In South America and North Ameri
The density, or more the volumetric mass density, of a substance is its mass per unit volume. The symbol most used for density is ρ, although the Latin letter D can be used. Mathematically, density is defined as mass divided by volume: ρ = m V where ρ is the density, m is the mass, V is the volume. In some cases, density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials have different densities, density may be relevant to buoyancy and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative density" or "specific gravity", i.e. the ratio of the density of the material to that of a standard material water.
Thus a relative density less than one means. The density of a material varies with pressure; this variation is small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a fluid results in convection of the heat from the bottom to the top, due to the decrease in the density of the heated fluid; this causes it to rise relative to more dense unheated material. The reciprocal of the density of a substance is called its specific volume, a term sometimes used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density. In a well-known but apocryphal tale, Archimedes was given the task of determining whether King Hiero's goldsmith was embezzling gold during the manufacture of a golden wreath dedicated to the gods and replacing it with another, cheaper alloy.
Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated and compared with the mass. Baffled, Archimedes is said to have taken an immersion bath and observed from the rise of the water upon entering that he could calculate the volume of the gold wreath through the displacement of the water. Upon this discovery, he leapt from his bath and ran naked through the streets shouting, "Eureka! Eureka!". As a result, the term "eureka" entered common parlance and is used today to indicate a moment of enlightenment; the story first appeared in written form in Vitruvius' books of architecture, two centuries after it took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time. From the equation for density, mass density has units of mass divided by volume; as there are many units of mass and volume covering many different magnitudes there are a large number of units for mass density in use.
The SI unit of kilogram per cubic metre and the cgs unit of gram per cubic centimetre are the most used units for density. One g/cm3 is equal to one thousand kg/m3. One cubic centimetre is equal to one millilitre. In industry, other larger or smaller units of mass and or volume are more practical and US customary units may be used. See below for a list of some of the most common units of density. A number of techniques as well as standards exist for the measurement of density of materials; such techniques include the use of a hydrometer, Hydrostatic balance, immersed body method, air comparison pycnometer, oscillating densitometer, as well as pour and tap. However, each individual method or technique measures different types of density, therefore it is necessary to have an understanding of the type of density being measured as well as the type of material in question; the density at all points of a homogeneous object equals its total mass divided by its total volume. The mass is measured with a scale or balance.
To determine the density of a liquid or a gas, a hydrometer, a dasymeter or a Coriolis flow meter may be used, respectively. Hydrostatic weighing uses the displacement of water due to a submerged object to determine the density of the object. If the body is not homogeneous its density varies between different regions of the object. In that case the density around any given location is determined by calculating the density of a small volume around that location. In the limit of an infinitesimal volume the density of an inhomogeneous object at a point becomes: ρ = d m / d V, where d V is an elementary volume at position r; the mass of the body t