Rug Colors and Dyes
The variations found in rugs and kilims around the world are amazing and beautiful. The color combinations present in a kilim or persian rug make it appealing to the eye and a wonderfully decorative work of art. Each color hides a meaning which contributes to it’s fascination. Early rugs and kilims of course used dyes obtained from vegetable
and animal sources. In modern times synthetic dyes (aniline or chrome) are also used
and make rugs more affordable to the average person. The following is a list of some of the most common uses of color in rugs today and from times past.
• Red is the color of fire, enthusiasm, courage, virility, faith, luck and joy. However,
it also carries the idea of sorrow and calamity.
• Orange stands for humility and piety.
• Blue symbolizes a sense of strength and power or force
• Green is used sparingly and only in place which are unlikely to be trodden on.It also means
hope, life, renewal and spring.
• Natural dyes: Vegetable and Animal
Time-consuming, pricey and tiresome are adjectives generally connected to the description of the making and using of natural dyes, both vegetable and animal. Whenever vegetable and animal sources are abundant in the area where kilims or rugs are manufactured the situation
changes and it becomes financially feasible to use vegetable or animal dyes. The sources
of these dyes may vary from country to country but the most common are the following:
• .Indigo:(originally obtained by extracting and fermenting indican from the leaves of the indigo plant) Produces Dark navy blue
• Madder: redroot of the madder plant;(produced by boiling the dried, chunked root of the
madder plant in the dye pot) Produces dark, rusty red.
• Red: cochineal insect
• Yellow: weld, vine leaves or pomegranate peel. produces muted gold
• Brown : walnut shells or oak bark
• Green: combination of weld and indigo
• Purple: hollyhocks
• Black: walnuts
• Larkspur: plant
• Henna: leaves and flowers
An observation should be made regarding slight changes in color usually seen in older rugs for this happens when the weaver starts weaving with a yarn from a different dye lot than the one previously used .This peculiarity is common when working with natural dyes since it is quite difficult to get an exact color match. Fortunately, this condition does not affect the value of the rug. It may in fact increase it’s value.
It is very common on tribal rugs to see this variation in color and is a unique characteristic of hand made rugs. The exact “recipe” used by a particular rug maker was a closely guarded secret which passed from generation to generation, or sometimes died with the passage of time and the rug maker. The nomads who made kilims could not produce a large batch of dye, therefore sometimes the color would vary from lot to lot in that way as well.Also the type and quality of wool was a factor in the final color result.
Long ago dyers realized that as more wool was dyed in a single dyepot, colors became weaker and weaker. Dyers use this notion of depleted dyes to their advantage. The first dyeing produces a deep, strong color. Subsequent dyeings in the same dyepot produce lighter,
softer colors
• Synthetic Dyes: Aniline Dyes
Aniline dyes were speedily adopted in the carpet industry due to their low cost and easy-to-use characteristic. The use of them was not limited to a specific area but spread throughout the world. In the last years of the nineteenth century aniline dyes were strongly acidic which damaged the quality of the rug by destroying the natural oil in the wool causing the rug to wear off in no time. In addition, the colors ran when the kilim was washed or faded if the rug was exposed to sunlight.
Because of these problems, aniline dyes are not used as much as they used to be. Nowadays they are used in the dyeing of inferior-quality rugs. If you do not know whether your precious kilim or persian style rug was aniline dyed. You should rub a damp cloth over the pile. If the rug was dyed with a good-quality vegetable or chemical dye it will not rub off onto the cloth, but if it does then your rug has been dyed with aniline.
• Synthetic Dyes: Chrome Dyes
At present, oriental rugs are dyed with Chrome dyes. In contrast to natural dyes, these are simpler to use, quite cheaper and their dye is much easier to match. Chrome dyes offer a greater range of shades and colors which are colorfast. The natural oils of the wool are not removed so the kilim will not be worn off as fast as an aniline dyed one. Although chrome dyes are widely used, in the past there were also complaints with them because their colors were harsher than the hues of natural dyes. This was corrected by the implementation of a light chemical wash which is done to most rugs before being exported to ensure the richness of the rug.
Rugs which are dyed in this way can never achieve the soft hue of a rug which is dyed with a natural dye. The rug fades a bit over time, depending on it’s exposure to the sun and general use, but the color which it achieves as a result is warm and unobtainable in any other way. The next time you look at your treasured rug or kilim, think of how it was dyed and appreciate it’s beauty all the more. Kilims and rugs are wonderful to behold!
c 2206 Bill Kernodle
Bill Kernodle is a rug enthusiast,art lover,world traveller and owner- operator of Revelation Imports.com.You may see what he has to offer on rugs,antiques,gifts,collectibles and hand made items from around the world.
Hair Loss From Straighteners or Dyes
Ladies, over-treated hair is the leading cause of hair loss in women. Take a break from hair dyes, perms, relaxers, and the likes. According to the FDA, over the counter dyes and chemical treatments tend to be the highest of all complaints. Are you one of the many people that dyed their hair, only to have it fall out in clumps? You’re not alone. It has happened to many people. Now, what can we do about it?
Stop using relaxers. Whether these products contain lye, or are lye-free, they still do serious damage to you hair. Both products contain chemicals that ‘fry’ your hair. While that may sound harsh, it’s simply the truth. If you must use a relaxer, take precaution. Read the directions and follow them thoroughly. If you have sensitive skin, apply a thin layer of petroleum jelly to the calm to prevent irritation.
Unfortunately, there’s very little you can do to bring your hair back to its natural state. If you’ve noticed thinning and bald patches from excessive hair dying, stop dying your hair! Let your hair heal itself. It will take several weeks before you notice re-growth, unless, of course–you do more damage during the healing process. Then it will take longer. The moral of the story: be good to your hair, and it will heal itself over time.
Carefully comb wet hair, avoid brushes. Do not rush through the combing process. Whipping a comb through your hair pulls on the hair’s follicles. As does eleastic bands or pony tail holders. Remobve them carefully. Do not yank them out of your hair. In addition, do not use curling irons or blow dryers on a regular basis. Especially if you’ve noticed thinning or bald spots. Absolutely need gel or hair spray? Try alcohol-free styling products. The alcohols in gel and spray only makes dry damaged hair more susceptible to further breakage.
Should you decide to dye your hair. Try a semi-permanent hair dye, which will wash out in six to eight weeks. You should ALWAYS avoid metallic hair dyes. These are the culprits for a lot of hair related horror stories. Leave all dyes on for the specified amount of time. If the bottle tells you twenty-five minutes, don’t leave it on for thirty. Those extra five minutes can actually take its toll on your hair, promoting further damage. Always do a strand test to make sure that you’re not allergic to the dye you purchased.
Natural Easter Egg Dyes
There are so many possibilities in your kitchen to access natural colors for Easter Eggs. Spices, fruits, tea bags, coffee, frozen vegetables, and onions are all things you can use to naturally color your eggs. Clean coffee filters will hold the colored eggs until they are dry.
Use the following recipes to create the colors indicated:
–Yellow Fill a jar with water (enough to cover an egg) Add 2 tsp. ground Cumin and stir Heat the jar in the microwave 2 - 3 minutes Add the hard-boiled egg into the dye jar and let it sit overnight Remove the egg from the dye jar and place on a piece of paper to dry
–Orange Fill a jar with water (enough to cover an egg) Add 1/2 tsp. ground Turmeric and stir Heat the jar in the microwave 2 - 3 minutes Add the hard-boiled egg into the dye jar and let it sit overnight Remove the egg from the dye jar and place on a piece of paper to dry
–Black Currant Fill a jar with water (enough to cover an egg) Add 2 Black Currant tea bags to the jar Heat in the microwave 2-3 minutes Place the hard-boiled egg into the jar and let it sit overnight Remove the dyed egg and place on a piece of paper to dry
–Rose Hip Fill a jar with water (enough to cover an egg) Add 2 Rosehip tea bags to the jar Heat in the microwave 2-3 minutes Place the hard-boiled egg into the jar and let it sit overnight. Remove the dyed egg and place on a piece of paper to dry.
–Red Pour the liquid from a jar of pickled beets into a jar Heat for 2 - 3 minutes in the microwave Add the hard-boiled egg into the beet juice and let it sit overnight Remove the dyed egg from the dye bath and let it dry on a piece of paper.
–Blue Cut the red cabbage into thin slices and place into a pot filled with water Cook the cabbage until tender and there is lots of color in the water Pour the liquid into a jar Add the cooked egg into the jar and let it sit overnight
–Green Cook spinach greens and drain the liquid into a clean dye jar Add the hard-boiled egg into the dye jar and let it sit overnight Remove the egg from the dye jar and place on a piece of paper to dry
–Brown Pour some strong coffee into a dye jar Place the hard-boiled egg into the jar Let it sit overnight or for a few days to get a darker color
You can also paint the eggs with fresh or frozen berries. Simply crush the berries against dry boiled eggs. Try coloring on the eggs with crayons or wax pencils before boiling and dyeing them. Now you can eat the pretty eggs too!
Cereal think outside the bowl: this breakfast staple is getting a makeover with our dos and don’ts for filling your morning bowl
Let’s face it: Cereal is often guilty of almost every cardinal sins of nutrition. Sugar. Marshmallows. Food dyes. Artificial flavors. More sugar. But before it became an American breakfast staple with sky-high sugar counts, cereal had a clean record–as a nourishing food for health spa patients. In 1863, sanatorium operator and vegetarian lames Caleb Jackson invented the first cereal in an attempt to combat the digestive woes of a population that routinely ate meat for breakfast. The cereal, which he named Granula, was composed of heavy bran nuggets that required overnight soaking to be chewable.
Fast forward to the 1950s, when cereal morphed into an almost dessert-like food, with up to 56 percent sugar packed in one bowl! Today, many grocery aisles still overflow with not-so-healthful options, but fortunately, it is possible to return to cereal’s noble roots. The fight kind can provide a host of nutritional benefits, from fiber to B vitamins like folate and niacin to minerals like iron, magnesium, and selenium.
“I always recommend looking for a cereal that’s flaky or puffy as opposed to dense and nuggety; lighter cereals usually contain fewer calories per portion than more dense ones,” says Elisa Zied, MS, RD, author of Feed Your Family Right! and a spokesperson for the American Dietetic Association. With any cereal, it’s best to eat no more than 1-2 cups per serving, she advises. This can contain up to two whole-grain servings while leaving room for low-fat milk or other add-ons.
Be a Label Lover
“Look for three key numbers [on labels]: calories, fiber grams, and sugar grams,” says Zied. She recommends cereals that contain no more than 200 calories per cup, provide at least 4 g of fiber, and add up to less than 15 g of sugar per serving. Stay away from labels that list sugar, dextrose, and high fructose corn syrup as ingredients, particularly if they are among the first five ingredients.
Go Grainy
When selecting a boxed cereal, look for whole-grain varieties. Whole grains are high in fiber and can help prevent type 2 diabetes, heart disease, and even some cancers. To glean the full benefit of whole grains.
Beatrice Trum Hunter, author of A Whole Foods Primer, says you may want to avoid boxed cereals altogether. “They have a lot of additives that are not all that desirable. It would be not only more nutritious but less expensive to get whole grains either loose or in packages,” she says. Brown rice, barley, steel-cut oatmeal, quinoa, amaranth, millet, buckwheat, or bulgur can all provide a nutritious breakfast when cooked. Many health food stores have a bulk bin section featuring a variety of cereal grains. Hunter suggests soaking the grains with dried fruit overnight, and then adding sunflower seeds and a little half-and-half after cooking it in the morning.
Substitute for Sugar
A few final tips for boosting your morning bowl’s nutritional value: “An ideal way of sweetening cereal is to simply add some dried fruit–raisins or currants, dried apricots, prunes, mango, pineapple, or banana,” says Hunter. You can also reduce sugar by mixing sweetened cereals with less sugary ones. Or top with fresh fruit like berries and a sprinkle of stevia or drizzle of honey.
Bowled Over!
Fill your morning bowl with cereals that rank high in taste and nutrition–and give you staying power for the day ahead, Here are a few to try.
Kashi Mountain Medley Granola
Often associated with high fat and calories, granola is now guilt-free and deliciously indulgent, thanks to Kashi. Their MOUNTAIN MEDLEY GRANOLA is a sweet mix of sundried cranberries, raisins, almonds, pecans, sunflower seeds, and crunchy whole grains. Also available in Orchard Spice blend.
FLAX PLUS PUMPKIN RAISIN CRUNCH is the newest addition to the Nature’s Paths Flax Plus line of cereals, and it’s already one of the company’s most popular cereals. This nutrient-packed blend redefines power breakfast with 650 mg of omega-3 fats per serving, 16 g of whole grains, 9 g of fiber, and 340 mg of potassium-and great taste too.
Mom’s Best Naturals Sweetened Wheat-fuls
Let your kids eat sweetened cereals again–without worrying about their health or weight. SWEETENED WHEATFULS satisfies sugar cravings while also providing a filling breakfast option. Each serving of the whole-grain wheat cereal has 6 g of fiber and 11 g of sugar . Other varieties include Raisin Bran, Honey Nut Toasty O’s, and Mallow Oats.
Two-Dimensional Standing Wave Total Internal Reflection Fluorescence Microscopy: Superresolution Imaging of Single Molecular and Biological Specimens
The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium.
Historical review of TIRF microscopy and superresolution microscopy In the modern era of biological research, fluorescence microscopy is a powerful tool to visualize specific biomolecules to which fluorescent dyes can be selectively bound. Total internal reflection fluorescence (TIRF) microscopy recently has emerged as the method of choice to probe cellular processes near the basal plasma membrane of adherent cells by illuminating a very thin region on the order of 100 nm . The evanescent wave intensity decays exponentially from the interface, and this near-field excitation volume allows intrinsic optical sectioning to less than one-fifth of the excitation wavelength while keeping wide-field (WF) imaging capability. Although conventional WF fluorescence excitation generates out-of-focus emission, the selective excitation of TIRF removes the out-of-focus noise and reduces photobleaching of fluorophores outside the focal plane and is thus ideal for single-molecule imaging. On the other hand, TIRF does not allow deeper imaging into the interior of cells, and the lateral resolution of TIRF is identical to that of standard WF imaging.
The quest to image structural and functional biological information using far-field microscopy at high resolution has been hindered by the diffraction limit of light. The Abbe diffraction limit originates from the wave nature of light and depends on the wavelength and the numerical aperture (NA) of an objective lens. When an object that is substantially smaller than the diffraction limit is imaged by a microscope, its image would be significantly broadened compared to the original object. The intensity distribution of this effective point object is defined as the point spread function (PSF). The commonly accepted Rayleigh criterion defines the resolution as the distance between two point objects when one PSF falls on the first zero point of the other PSF, which can be barely distinguished in incoherent imaging. Also Sparrow suggested a resolution criterion when the gradient of the summed profile is zero or no dip at the midpoint . These resolution definitions are roughly equal to the full width at half-maximum (FWHM) of the PSF. With typical visible light emission and oil-immersion objectives, optical resolution is over 200 nm.
The lateral resolution mostly depends on the evanescent SW fringe period, which is proportional to the excitation wavelength in the substrate. As with other high resolution techniques based on interference, there exists a side-band artifact. This artifact can be easily removed by linear deconvolution if the emission PSF is narrow enough to keep the side-band lower than 30% . Thus this effectively enhances the resolution much more than twofold, as demonstrated in this article.
Since the SW modulation is inherently sinusoidal, to reconstruct the high resolution in the direction of the S W, a minimum of three image acquisitions at different phases of the SW are required. Since phase shift is in principle fast, SW-TfRF does not necessarily increase the total image acquisition time compared to conventional WF imaging.
Second Harmonic Generation in Neurons: Electro-Optic Mechanism of Membrane Potential Sensitivity
Second harmonic generation (SHG) from membrane-bound chromophores can be used to image membrane potential in neurons. We investigate the biophysical mechanism responsible forthe SHG voltage sensitivity of the styryl dye FM 4-64 in pyramidal neurons from mouse neocortical slices. SHG signals are exquisitely sensitive to the polarization of the incident laser light. Using this polarization sensitivity in two complementary approaches, we estimate a ~36° tilt angle of the chromophore to the membrane normal. Changes in membrane potential do not affect the polarization of the SHG signal. The voltage response of FM 4-64 is faster than 1 ms and does not reverse sign when imaged at either side of its absorption peak. We conclude that FM 4-64 senses membrane potential through an electro-optic mechanism, without significant chromophore membrane reorientation, redistribution, or spectral shift.
Two-Dimensional Standing Wave Total Internal Reflection Fluorescence Microscopy: Superresolution Imaging of Single Molecular and Biological Specimens
The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium.
In the modern era of biological research, fluorescence microscopy is a powerful tool to visualize specific biomolecules to which fluorescent dyes can be selectively bound. Total internal reflection fluorescence (TIRF) microscopy recently has emerged as the method of choice to probe cellular processes near the basal plasma membrane of adherent cells by illuminating a very thin region on the order of 100 nm (1,2). The evanescent wave intensity decays exponentially from the interface, and this near-field excitation volume allows intrinsic optical sectioning to less than one-fifth of the excitation wavelength while keeping wide-field (WF) imaging capability. Although conventional WF fluorescence excitation generates out-of-focus emission, the selective excitation of TIRF removes the out-of-focus noise and reduces photobleaching of fluorophores outside the focal plane and is thus ideal for single-molecule imaging (3,4). On the other hand, TIRF does not allow deeper imaging into the interior of cells, and the lateral resolution of TIRF is identical to that of standard WF imaging.
The quest to image structural and functional biological information using far-field microscopy at high resolution has been hindered by the diffraction limit of light. The Abbe diffraction limit originates from the wave nature of light and depends on the wavelength and the numerical aperture (NA) of an objective lens. When an object that is substantially smaller than the diffraction limit is imaged by a microscope, its image would be significantly broadened compared to the original object. The intensity distribution of this effective point object is defined as the point spread function (PSF). The commonly accepted Rayleigh criterion defines the resolution as the distance between two point objects when one PSF falls on the first zero point of the other PSF, which can be barely distinguished in incoherent imaging. Also Sparrow suggested a resolution criterion when the gradient of the summed profile is zero or no dip at the midpoint (5). These resolution definitions are roughly equal to the full width at half-maximum (FWHM) of the PSF. With typical visible light emission and oil-immersion objectives, optical resolution is over 200 nm.
The challenge of achieving superresolution in optical microscopy beyond the diffraction limit has been overcome in practice only during the last couple of decades. In particular, extending lateral or transverse resolution has been exemplified with several techniques such as i) stimulated emission depletion (STED) microscopy, ii) saturated structured illumination microscopy (SSIM), iii) solid immersion lens (SEL), iv) structured illumination microscopy (SIM), and v) harmonic excitation light microscopy (HELM).
Since the SW modulation is inherently sinusoidal, to reconstruct the high resolution in the direction of the S W, a minimum of three image acquisitions at different phases of the SW are required. Since phase shift is in principle fast, SW-TfRF does not necessarily increase the total image acquisition time compared to conventional WF imaging.
The lateral resolution mostly depends on the evanescent SW fringe period, which is proportional to the excitation wavelength in the substrate. As with other high resolution techniques based on interference, there exists a side-band artifact. This artifact can be easily removed by linear deconvolution if the emission PSF is narrow enough to keep the side-band lower than 30% (18). Thus this effectively enhances the resolution much more than twofold, as demonstrated in this article.
With the current design, conventional TIRF images can be simply obtained by blocking one beam and conventional WF images can be taken by locating one beam at the center of the optical axis while blocking the other beam. This will be used for the comparison of different imaging modes.
Calibration of evanescent standing wave fringe period
As mentioned in the above section, the direct imaging measurement of the evanescent SW period is not trivial, due to its subdiffraction limited size. Instead, a thin uniform layer of fluorescent sample was prepared and SW emission was imaged by gradually increasing the incident angles from a subcritical angle, where SW can be imaged, to a supercritical angle where the SW cannot be imaged due to the resolution limit. This actual measurement of imaging SW fringes was matched with theoretical calculation from geometry within 2.5% and could be extrapolated to the setup angle of 67° ± 0.5°. We further need to calibrate the pixel size of the CCD camera.
Cell Analysis System is offered with multilaser option
ImageStream[R] is offered with multilaser capability that lets users add 2 lasers, including 405 and 658 nm lasers, that promote experimental flexibility and complexity by expanding available fluorescent dye selection. Additionally, optical system has feature that provides chromatic correction for lower-wavelength dyes excited by 405 nm laser. This enables hi-res imagery, resulting from fluorescence excitation from all 3 lasers, to be simultaneously captured across visible spectrum.
Amnis Corporation announced today the release of two major upgrades to its ImageStream system including the Commercial release of a multilaser capability and the Beta release of a new technology for dramatically extending the depth of field well beyond conventional optical limitations.
The Multilaser upgrade provides the customer with the flexibility of adding two additional lasers including a 405nm (violet) laser and a 658nm (red) laser. These lasers provide for increased experimental flexibility and sophistication by greatly expanding the fluorescent dye selection available to the customer. The upgrade is accompanied by a novel enhancement to the optical system which provides precise chromatic correction for lower wavelength dyes excited by the 405nm laser. The enhancement enables high resolution imagery resulting from fluorescence excitation from all three lasers to be captured simultaneously across the entire visible spectrum. Customers who purchase the 405nm laser can now perform cell cycle, mitotic analysis and other experiments incorporating the widely-used DNA binding dyes DAPI and Hoechst. The 658nm red laser provides similar advantages for a broad range of red fluorescent dyes. The laser options have been designed for field-based installation and are currently being installed at existing customer sites throughout the world. New instruments are also being shipped per customer order with one, two or all three lasers installed.
The Extended Depth of Field (EDF) upgrade, currently in Beta testing at seven customer sites, has demonstrated up to a 10 fold increase depth of field allowing cellular structures to be imaged in crisp focus at positions well beyond the limitations of conventional imaging techniques. The EDF technology employs a Wavefront Coded(TM) optical element, developed by CDM Optics of Boulder, Colorado, operating in concert with rapid optical deconvolution algorithms developed by Amnis Corporation. The EDF option was specifically developed to address emerging research and clinical applications in high throughput cellular genetics. William Ortyn, Amnis COO, says “We are extremely pleased with the results of the this work. We now have several ongoing collaborations directed toward clinical testing of the ImageStream with the EDF option.” to enable the early detection of cancer.” Dr. David Basiji, Amnis CEO, states “The new capabilities enabled by both the Multilaser and EDF options bring new strengths to the platform to better serve our customer base. These options, in conjunction with our FISHIS(R) technology, also begin to lay the foundation for the advancement of the platform into the clinical marketplace.”
Amnis Corporation, headquartered in Seattle, WA, develops, manufactures and markets the ImageStream system for high speed imaging of cells in flow. The ImageStream system generates six high resolution microscopic images of cells as they flow through the instrument at rates up to 300 cells per second. Offering a truly unique combination of the visual power of microscopy and the statistical power of flow cytometry, the ImageStream system enables scientists to conduct highly advanced research in hematology, immunology and oncology.
Aggregation of direct dyes investigated by molecular modeling
Molecular modeling simulating aqueous conditions is used to elucidate the formation of aggregates of sulfonated chromophores, including Congo Red and Trypan Blue. The relative energies involved in the aggregation process are calculated and geometric features of the molecules and their aggregates are discussed. Parallel stacking facing one another occurs with slight shifts along the long axes of the chromophores to accommodate the sterically demanding sulfonate groups. The Connolly surfaces and volumes of the individual molecules as well as their aggregates are determined.
As part of a larger investigation using direct dyes as molecular sensors to characterize different cellulose substrates, we noted that the tendency of these dyes to form aggregates requires elucidation. Results from our dyeing experiments [3] appeared to indicate that, even when dilute solutions of the dyes were employed to obtain Langmuirian adsorption, aggregates of different sizes rather than single molecules might have been adsorbed onto the surfaces, depending on the dye. Thus we used molecular modeling to obtain a better understanding of aggregate formation under these conditions.
Molecular modeling has been successfully applied to a diversity of problems to characterize properties that are extremely difficult to assess by experiment [5, 6, 9, 11]. With respect to dyes, molecular modeling has been employed, for instance, to characterize the geometry of direct and disperse dyes [7, 10, 17]. Aggregation was modeled by Skowronek et aL [12, 13], who extensively used various modeling techniques and force fields to elucidate the geometry and self-assembly of direct dyes. The supramolecular organization of Congo Red was studied because of its unusual complexation characteristics associated with liquid crystal formation. Since liquid crystal formation requires high concentrations of electrolyte and dye, the dyes were modeled in their neutral form. A critical consideration is the fact that modeling calculations are typically based on a gas phase model at a dielectric constant of 1 [11]. However, this class of dyes is usually applied from aqueous solution. Of concern, then, is the question of how well such modeling calculations relate to the solution state. Modeling software addresses the problem in various ways. The molecular mechanics software (Amber 4.1) used by Skowronek et al. [13] permits placement of a water shell around the supramolecular system while maintaining a dielectric constant of 1.
Urukawa et al. [16] used Allinger’s MM2 force field to study aggregation of acid dye molecules, including Azorubin, in order to estimate intermolecular distances between the two molecules forming a dimer. These researchers reported a shifted, parallel-stacked geometry for the Azorubin dimer with an intermolecular distance of about 6A. In general acid dyes are smaller than direct dyes, but are similar to the latter in that they are also azo dyes and have negatively charged sulfonate groups. Azorubin consists of a naphthalene ring connected at its 4-position by an azo-linkage to the 7-position of a second naphthalene group.
For this study, we use molecular mechanics calculations to generate geometries and energies involved in aggregation processes of six direct dye molecules. The dyes are presented in Table I together with the codes used in the text. Five of the molecules under investigation for this study-C.I. Direct Red 28, C.I. Direct Red 2, C.I. Direct Blue 1, C.I. Direct Blue 14, and C.I. Direct Blue 53-are related in that they have the same backbone (Figure la, b). However, dyeing experiments have shown that they can differ significantly in dyeing behavior [3]. It appears that the type, number, and position of functional groups help determine their aggregation properties, which in turn, may affect their dyeing behavior.
Thus our goal in this work is to use molecular modeling as a tool to explore what kind of aggregate formation is possible, the geometries involved, and whether there is a limit beyond which aggregate growth is no longer energetically favorable. In addition, we determine the Connolly surfaces and volumes of the individual dye molecules and their aggregates to obtain an estimate of their size.
A Connolly surface is the van der Waals surface of a molecule that is accessible to a solvent molecule, in this case water. Such a surface is generated by rolling a probe sphere over the van der Waals surface of the molecule of interest. The surface consists of three components: contact, saddle, and concave surfaces. The contact surface comprises those atoms that are accessible to the probe sphere. The saddle-shaped and concave surfaces are denoted as reentrant surfaces and represent the boundary at the volume from which a probe sphere is excluded if it is not to experience van der Waals overlap with the atoms .
Cerius 2 by Molecular Simulations Inc. with the Universal Force Field was employed, as well as CAChe by Oxford Molecular Group. For all experiments performed with Cerius 2, a dielectric constant of 78 was used corresponding to water. The temperature default was absolute zero. Geometry optimizations of one to ten molecules per aggregate were performed for the six dyes under investigation. All dye molecules were treated in their anionic form to model the system as closely as possible to our experimental practices, i.e. aqueous solutions at low concentrations of dye and electrolyte. Under such conditions, the anionic chromophore and its counterion are separated by a large distance [81, such that in this exploratory investigation, the Na+ counterions were omitted. Geometry optimizations of all individual dye molecules were performed prior to assembling them into various starting positions for the aggregation experiments. Geometric optimization procedures on larger aggregates (those containing three to ten chromophores) were performed by manually assembling individually optimized molecules and/or dimers. Intermolecular distances for the manual placement of individual molecules forming dimers, two dimers forming aggregates containing an even number of molecules, as well as individual molecules and dimers to build aggregates with odd numbers of molecules per aggregate, were manually varied from approximately 2.5 to 20Angstrom. Only the most energetically favorable configurations of the dimers were stacked for aggregate assembly. Stacking occurred with the ring systems of the chromophores lined up face-to– face.
The Connolly surface areas and volumes were calculated for all single molecules and all aggregates. Dot displays of the van der Waals surfaces were generated to illustrate the solvent accessible surfaces of the molecules and aggregates. To calculate the Connolly surface areas of the molecules and aggregates, the probe sphere radius was set to 1.4Angstrom, corresponding to the van der Waals radius of water. Conformational analyses were performed with CAChe using the MM2 force field.
Skin salvation: slough off scaly winter skin and perk up drab coloring with luscious—and cruelty-free—natural cosmetics
Don’t blush. With three solid months of winter behind us, no one will blame you for having the skin of a cranky crocodile. “When the temperature drops and the relative humidity decreases, the upper layers of your skin lose a large amount of water,” explains dermatologist Jerome Z. Litt, MD, in his book, Your Skin From A to Z. And because the moisture in deeper layers can’t work its way up to the surface, the result is “scales” and flakes on skin’s top layer.
Skin isn’t safe indoors either. “The lower humidity is aggravated by artificial heat, which, in addition to warming the air, dries it,” writes Litt. That dry, heated air sucks moisture out of everything–including skin.
At the end of winter, as humidity rises and we stop turning up the heat, skin will slowly return to normal. But why wait? This is the ideal time to jettison your usual products and try something new. To get you started, we went searching for body care companies offering organic, pure products–an approach that’s sensible no matter what your skin type. “Most people have some kind of sensitivity,” says Los Angeles–based dermatologist Debra B. Luftman, MD. “The more preservatives and perfumes a product contains, the greater the possibility that it will irritate skin.”
The people who make the following products list the ingredients on either the package or their websites. All of these companies are also committed to making the planet a better place–whether by supporting fair trade or by urging consumers to recycle used shampoo bottles–and their products are cruelty-free. Which means that even your inner reptile will feel well cared for.