Coffee staining

An example of a symmetry operation is rotation of an object about an axis. To illustrate with a familiar object, if a rectangular table is rotated 180" about an axis perpendicular to and centered on the tabletop (Fig. 4.14), the table looks just the same as it did before rotation (ignoring imperfections such as coffee stains). We say that the table possesses a twofold rotation axis because, in rotating the table one full circle about this axis, we find two positions that are equivalent 0" and 180". The axis itself is an example of a symmetry element. 

Deegan et gave three conditions that need to be met by the droplet in order for coffee staining to occur. These conditions are that the solvent meets the substrate at a non-zero contact angle, the contact line is pinned and that the solvent is volatile. These conditions were subsequently refined to being a pinned contact line and evaporation from the edge of the droplet. ... 

The actual conditions that are the cause of coffee staining continue to generate debate mostly centred on the question of whether the contact line is initially pinned. Deegan used droplets of a colloidal suspension on atomically smooth mica to explore the issue of self-pinning. He said that rings form because the contact line cannot move and that some pre-existing conditions on the substrate temporarily anchor it until sohd material accumulates. However,... 

Fig. 3. Phase contrast microscopy images of silica particle coffee stains on glass. The particle size is 0.33 /xm, 1 /xm and 3 m from left to right. The coffee stains were formed from aqueous droplets, which were produced by inkjet printing. It can be seen that the dried droplet composed of 3 m particles has the smallest diameter. The cartoon illustrates that smaller particles can deposit nearer to the contact line. (From Ref. 15, 2008 The Royal Society of Chemistry.)...

Make sure, too, that your paper looks professional before you turn it in. You wouldn t, after all, expect to be taken seriously if you went to an executive job interview dressed in cutoffs. Turning in a paper with a coffee stain or ink blot on it has about the same effect as a blob of spinach in your teeth—it distracts folks from hearing what you have to say. If your final draft has typos or small blemishes, use correction fluid to conceal them if you ve patched so frequently that your paper resembles the medicine-dotted face of a kindergartner with chicken pox, photocopy or reprint your pages for a fresh look. 

Or, to take a more mundane example, if a set of operating procedures is messy—crumpled, coffee-stained, and scribbled on—then the factors indicate a poor culture. But possibly not it could be that the condition of the procedures shows that the technicians are using them a lot and so the culture is good. Once more, the measurement of culture in a context such as this is problematic. 

C. Nobile, L. Carbone, A. Fiore, R. Cingolani, L. Manna, R. Krahne, Self-assembly of highly fluorescent semiconductor nanorods into large scale smectic liquid crystal structures by coffee stain evaporation dynamics. J. Phys. Condens. Matter 21, 264013 (2009)... 

De Leon, A.S., Del Campo, A., Femandez-Garcia, M., Rodrlguez-Hemandez, J., Munoz-Bonilla, A. Tuning the pore composition by two simultaneous inteifacial self-asstanbly processes breath figures and coffee stain. Langmuir 30, 6134—6141 (2014)... 

In this section we focus on some of the most important features of evaporating sessile drops the scaUng resulting from the above model and the consequences of the spatial nonuniform evaporation current commonly known as the coffee stain or donut effect. 

Coffee stains are a very clear example of surface patterning by means of evaporation. Since the patterns are predominantly created in the vicinity of the contact Une, high-resolution patterns are achievable by surprisingly simple means. However, what has been discussed so far is just one particular scenario generally various mechanisms are involved in pattern formation. A list of the most important ones is given below [4]. 

Droplet Evaporation, Figure 3 (a) Coffee stain arising from a nearly... 

The Clever Salesman evaluates his prey. I hope he s an important decision maker. Dilbert Take any seat. I call the good chair Salesman Warning Cubicle Low-ranking employee Dilbert Here s our organizational chart President. .. Senior Vice President. ..Vice President... Ok, Lift your foot. Do you see the coffee stain on that carpet Salesman That s you Dilbert No, that s my boss. I would be under the carpet (Adams, 1995). 

Safety cases are no different from any other safety document—their value hes not in the quality of the material that is developed and presented, but in the degree to which that material is used. A short, poorly printed safety case that is dog-eared and splattered with coffee stains has achieved its goals. A thoroughly researched, carefully printed safety case that is in pristine condition may have helped in the development of a safe initial design, but it is not making an ongoing contribution to safety and efficiency. 

Tea contains colored flavonoid polymers, such as theaflavines, and polyphenols [14] which have a considerable affinity to nylon. In the United States, tea stain on carpets has been a lesser problem than coffee stains. The color of tea... 

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