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How well do Eppendorf cups seal?

How well do Eppendorf cups seal?


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I am considering to send some samples overseas in Eppendorf cups. They are the standard plastic cups of 1 to 2 mL capacity. Of course they may tip over during their journey and I'd like to know how well they seal or if there is any danger that anything leaks from inside the cup. The samples are fixed in alcohol if that is relevant.


I have never had problem with tubes leaking. However, if you are worried about them getting somehow popped open in transit, you might consider wrapping the lid in parafilm. Alternately, there are lid locks that you could use like these.

@Chris has a good point about screw-cap tubes, they could also work, and are probably a lot sturdier, in case of actual damage.


Centrifuge Safety

Rotors spin very rapidly and generate extreme forces. It’s therefore crucial to properly balance rotors during runs, especially when rotors are only partially loaded with tubes or plates. Balancing is always important (in order to not decrease the lifetime of the rotor), but especially so when centrifuging at higher speeds. Despite your efforts, however, imbalance errors caused by unbalanced sample loads can occur.

What risks do I face when exposed to an imbalanced load?

Incorrect loading can reduce the lifetime of the rotor, and uncontrolled, heavy vibration can lead to permanently damaging the centrifuge. More importantly, however, an imbalanced load can injure you or someone else. In the worst case, an imbalance can lead to a rotor crash.

Does my centrifuge realize the load is imbalanced?

Many centrifuges have auto-imbalance detection and will decelerate or automatically shut off if they sense an excessively unbalanced load (sensors are specifically built into the centrifuge for this purpose). Mostly bigger models (large benchtop and floor-standing centrifuges as well as ultracentrifuges) have this option. Smaller benchtop models, on the other hand, do not create strong enough forces to cause harmful imbalances with these models, you would just notice a slight vibration and/or a higher noise level. Be aware that auto-imbalance detection does not automatically compensate for an unbalanced load.

What do I have to do if an imbalance error occurs?

If the centrifuge begins to shake or wobble, it is off-balance and you should stop it immediately. A little vibration is normal, but excessive amounts can mean danger. Once you have stopped the centrifuge, first double check to see if you have correctly balanced the tubes or plates in the rotor or buckets. If they are correctly balanced and the wobbling still occurs, contact the manufacturer or dealer to get the unit serviced. Do not continue to run a centrifuge that visibly wobbles when the rotor is spinning.

How do I avoid centrifuge imbalances in the first place?

Ensure that your work surface is level and firm. Do not use the centrifuge on an uneven or slanted work surface.

At high speeds, a centrifuge can easily become unbalanced if equal masses are not located opposite each other in the rotor:

For fixed-angle rotors, balance your tubes according to their weight. Load the rotor symmetrically and ensure the opposing tube is not only the same type of tube, but that it is also filled with the same mass. If the number of tubes with samples is uneven, counterbalance using water in an additional tube. Remember to balance the mass (weight) of the tubes, not the volume (size). Weigh the tube with your sample and record the mass. If you are spinning more than two tubes, only the tubes directly opposite each other have to be equal in mass.

For swing-out rotors, always load all rotor positions with buckets (incomplete loading of the rotor may reduce the lifetime of the rotor). The weight of the maximum load or maximum weight of the completely loaded bucket is specified (weight class) on the buckets. Do not exceed this weight. When loading the buckets, make sure the tubes or plates are placed symmetrically.

Always check to see that the buckets swing out smoothly. If they do not, clean the pivots and grooves and apply grease.


Centrifuge Maintenance

It’s the same for everything that’s important to you – if you treat it properly and handle it with care, you will be able to enjoy it for a long time.
Your centrifuge was surely not cheap. No wonder, considering the amount of technical innovation, human effort and precious materials involved in creating this valuable device. You probably intend to use it for a scientific or medical research or an innovation that makes our daily lives easier in some way. And you would like to work towards these goals without any problems along the way. This is why you should care for it – on a daily, weekly and annual basis. We are going to show you how to do that correctly and effectively.
First, pay attention to the manufacturer’s recommendations. If you can’t find what you are looking for in the user manual, contact the manufacturer. Otherwise you risk damaging the centrifuge, accessories or rotors. Please also check the centrifuge regularly for damage caused by corrosion.

Cleaning & disinfection

! Switch off the device and disconnect it from the power supply before starting any cleaning or disinfection.

  • The outside of the centrifuge and the rotor chamber should be cleaned regularly with neutral detergents. This is for hygienic purposes as well as to prevent contamination caused by residual contamination.
  • Only neutral agents may be used for cleaning and disinfection (e.g. diluted neutral alcohol-based disinfectant or 70% isopropanol mixture).
  • Residue from detergents should be removed. Also remove condensation and clean the condensation tray. Leave the centrifuge lid open.
  • The rotor chamber and the rotor shaft should simply be wiped with a moist cloth. Please clean your rotor using a neutral cleaning liquid. This will protect the rotor and prolong its service life.

! Do not use acetone, caustic detergents, or detergents that contain chlorite ions. Corrosion is most frequently caused by using chlorite ion solutions, such as sodium hypochlorite (household bleach). Do not use steel wool, wire brushes, abrasives, or sandpaper, since they may damage the rotor coating (anodized coating) and thus increase the risk of corrosion. We do not recommend putting rotors or lids into the dishwasher, since the aggressive cleaning agents used in dishwashers may result in corrosion.

Rotors & accessories

When using a swing-bucket rotor, ensure that the bucket grooves are free of contamination. The buckets can be lubricated with a lubricant (grease for pivots). Ensure that the buckets can swing out completely, especially when using new tube formats.

! If aggressive liquid is spilled on your centrifuge equipment, clean it immediately with a neutral cleaning liquid (alcohol or alcohol-based disinfectant). This will protect the rotor and prolong its service life.
! Since salt crystals located on the metal surface will corrode the surface, we strongly recommend cleaning the equipment immediately after every use.

If there is a stubborn stain, clean with a plastic scrub pad. If you need to clean the rotor’s tube cavities or boreholes, use a stiff test-tube brush that has end bristles and a non-metallic tip. Rinse equipment with distilled water and dry thoroughly with a soft cleaning cloth.
Do not submerge the rotor in water completely, since water can remain in the rotor cavities, leading to imbalances during following runs.

Suitable and unsuitable cleaning devices:

  • Plastic scrub pad
    (in case of stubborn contamination)
  • Stiff brush with end bristles and a non-metallic tip
    (if you need to clean the rotor’s bore holes)

Decontamination / disinfection

Contamination of the rotor through biological material (such as blood) or radioactive material may occur even when you work accurately and carefully. If this happens, please consult your laboratory safety officer first about suitable methods of cleaning and disinfecting hazardous spills within the centrifuge/rotor. Successful disinfection can only be granted by the suppliers of the chemicals.
Before using any cleaning or disinfection method other than what is recommended by the centrifuge manufacturer, please check that the intended method will not damage the rotors, accessories, or other parts of the centrifuge.
Please be aware that the detergents and disinfections are only recommended due to their compatibility with material of the centrifuges. The recommended methods for decontamination are disinfection with alcohol-containing liquids and autoclaving.
! Do not use UV, beta, gamma, or any other high-energy radiation source for disinfection. Do not use gas for disinfection.

In general, disinfection with a cloth is more efficient than spraying liquids on the centrifuge, which may also result in a short-circuit within the centrifuge housing. After cleaning with detergent, the rubber seals in the rotor chamber should be rinsed well with distilled water and lubricated with glycerine to prevent them from becoming brittle.

Autoclaving

The sterilization of rotors and accessories may be desirable to protect humans from pathogens or samples from contamination. Sterilization is a process that eliminates all forms of microbial life, including transmissible agents such as bacteria, viruses, fungi, spore forms, etc.
A widely-used method for heat sterilization is autoclaving, where equipment and other objects are sterilized with hot steam. For instance, a typical autoclaving program is performed at 121 °C and 2-bar atmospheric pressure for 15 to 20 minutes.

All fixed-angle and many swing-out rotor crosses as well as all buckets from Eppendorf have been rigorously tested and approved under these conditions. They also have a special anodized coating, which protects the metal from deeper corrosion effects. Steel swing-bucket rotor crosses with a heat-fixed powder coating are not suitable for autoclaving. If you are in doubt about your rotor, please ask the manufacturer whether autoclaving is possible for that model.

Eppendorf offers a second type of aluminum fixed-angle rotor with a special PTFE coating, which has outstanding chemical resistance against phenol, acetonitrile, DMSO, acetone, trichloroacetic acid, acetic acid and sodium hypochlorite. This coating is applied on top of the actual anodic coating.

In some cases, autoclaving at temperatures of 121 °C for 20 minutes may not be sufficient to sterilize a rotor. Prions, such as those associated with Creutzfeld-Jakob disease, can not be destroyed in these conditions. Some manufacturers state that autoclaving at 134 °C for at least 18 minutes should be sufficient [1], but in some cases, even this is not enough to deactivate the disease agent, especially when using material with very high infectiousness. Prions generally have a high heat resistance, although their infectivity can be reduced by such a treatment.

A maximum temperature of 121 °C is not suitable for the destruction of prions. Therefore, higher temperatures are necessary. According to available marketing material, only a few rotors on the market can be autoclaved at higher temperatures than 121°C. The customer thus has a very limited choice of available rotors – including Eppendorf’s high-quality aluminum rotors –for these applications. Selected Eppendorf rotors have been extensively tested at 142 °C for 2 hours or 135 °C for 20 min. These Eppendorf rotors can be used with confidence for such applications.


Choose the right ART tip for your pipette and application

Self-sealing barrier tips

ART barrier pipette tips are ideal for use with your most valuable samples and sensitive assays to prevent contamination, while protecting your pipettes, too.

  • PCR
  • DNA and RNA purification
  • Pipetting radioactive agents
  • Protein biology
  • Cell culture
  • Biobanking

Non-filtered tips

ART non-filtered tips are the same high-quality tips as ART barrier tips.

SoftFit-L filtered tips

ART SoftFit-L filtered tips block aerosol particulates, formed during aspiration, from entering the pipette, preventing cross contamination. The positive-stop design reduces tip attachment and ejection forces. For use with Rainin™ LTS pipettes.


Bio-inspired suction cups withstand more than splashes

Suction cups are getting a facelift. A shower caddy full of shampoo plopping into the bathtub may be an inconvenience in most cases, but failures like this limit the application of suction cups for more exacting purposes. Petra Ditsche, currently at the University of Alaska Anchorage, and her colleagues are changing that. To create prototype suction cups that are capable of glomming onto rough, wet surfaces and staying there, Ditsche has found inspiration in an aptly-named marine creature: the clingfish.

On the rocky shores of Washington State, clingfish maneuver over rocks to prey on limpets -- dime-sized, snail-like invertebrates. A limpet is covered by a shell shield that hides soft organs, which are fair game if the predatory clingfish can pop it off the rock. Yet the clingfish faces its own foe: heavy forces from incoming waves that threaten to slosh it off the rocks as it searches for food. The clingfish, however, has developed a unique system for holding onto rocks by using a suction cup on its underside, which has been derived from pelvic and pectoral fins.

Unlike a typical plastic suction cup, a clingfish disc isn't totally smooth -- the edge of the surface resembles that of a tongue, covered in irregular features. Looking closer, these tiny projections branch out even further, forming a hierarchy of structure. This provides the key to the clingfishes' tenacity: the friction generated from these little hairs allows the suction disc to remain staunch when the edges of typical plastic suction cups would be pulled in, eventually lifting off to break the seal. In a world where clingfish are buffeted by crashing waves, the suction disc allows them to remain in place even when forces 150 times their body weight are applied.

Ditsche and her colleagues are interested in biomimicry, a field that uses nature's solutions, refined in some of the toughest environments, for our own applications. This field of study has given us bullet trains shaped like kingfisher beaks, Velcro inspired by the burrs of plants, and fabric that glides through the water almost as well as shark skin.

Biomimicry is not about creating a one-to-one replica of the original inspiration, Ditsche says. Instead, it requires understanding of the underlying mechanisms so that the technology can be employed in a simplified yet useful manner. Ditsche has focused on replicating both the adaptability of the material to rough surfaces and the high friction at the margins of the suction cup that prevent the cup from being dislodged easily. Initial tests have shown that these biomimetic models have a grip of up to 70,000 Pascals on rough surfaces, equivalent to the pressure of 10 great white sharks stacked upon an office desk.

Ultimately, these super suction cups could be deployed during surgeries to pull tissue out of the way without risk of puncture or for use when climbing wet surfaces. Currently, they are slated to return to the waters where the clingfish that inspired them reside: the Puget Sound in Washington. Here, a population of endangered orca whales is tracked and carefully monitored by researchers. Once field-tested, these suction cups could provide a way to attach tracking tags in a less-invasive manner than current techniques. Bio-inspired design is re-entering the natural world to allow for even more research, taking any splashes in stride.


Groundwater Wells

Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts, people couldn't survive and thrive without groundwater, and people use wells to get at underground water.

Credit: Howard Perlman, USGS

Groundwater Wells

There's a good chance that the average Joe who had to dig a well in ancient Egypt probably did the work with his hands, a shovel, and a bucket. He would have kept digging until he reached the water table, where all the spaces between the rock and dirt particles are filled with water, and water filled the bottom of the hole. Some wells are still dug by hand today, but more modern methods are available.

Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts,people couldn't survive and thrive without groundwater.

Types of wells

Digging a well by hand is becoming outdated today as automated drilling methods replace manual-labor methods. Modern wells are more often drilled by a truck-mounted drill rig. Still, there are many ways to put in a well — here are some of the common methods.

Hacking at the ground with a pick and shovel is one way to dig a well. If the ground is soft and the water table is shallow,then dug wells can work. Historically, dug wells were excavated by hand shovel to below the water table until incoming water exceeded the digger's bailing rate. The well was lined with stones, brick, tile, or other material to prevent collapse, and was covered with a cap of wood, stone, or concrete. They cannot be dug much deeper than the water table — just as you cannot dig a hole very deep when you are at the beach. it keeps filling up with water!

Example of a pump and plumbing configuration used by public water systems.

Credit: Roland Tollett, USGS

Dug and bored wells have a large diameter and expose a large area to the aquifer. These wells are able to obtain water from less-permeable materials such as very fine sand, silt, or clay. Some disadvantages of this type of well are that they are shallow and lack continuous casing, making them subject to contamination from nearby surface sources, and they go dry during periods of drought if the water table drops below the well bottom.

DRIVEN WELLS

Driven wells are still common today. They are built by driving a small-diameter pipe into soft earth, such as sand or gravel. A screen is usually attached to the bottom of the pipe to filter out sand and other particles. Problems? They can only tap shallow water, and because the source of the water is so close to the surface, contamination from surface pollutants can occur.

DRILLED WELLS

Most modern wells are drilled, which requires a fairly complicated and expensive drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft, large auger bits. Drilled wells can be drilled more than 1,000 feet deep. Often a pump is placed in the well at some depth to push the water up to the surface..Wells and Pumpage

Water Levels in Wells

Groundwater users would find life easier if the water level in the aquifer that supplied their well always stayed the same. Seasonal variations in rainfall and the occasional drought affect the "height" of the underground water level. Withdrawing water from a well causes the water levels around the well to lower. The water level in a well can also be lowered if other wells near it are withdrawing water. When water levels drop below the levels of the pump intakes, then wells will begin to pump air - they will "go dry."

Pumping a well lowers the water level around the well to form a cone of depression in the water table. If the cone of depression extends to other nearby wells, the water level in those wells will be lowered. The cone develops in both shallow water-table and deeper confined-aquifer systems. In the deeper confined-aquifer system, the cone of depression is indicated by a decline in the pressure and the cone spreads over a much larger area than in a water-table system. For a given rate of withdrawal, the cone of depression extends deeper in low-yielding aquifers than in high-yielding ones.

Even though water is present at some depth at almost any location, the success of obtaining an adequate domestic supply (usually 5 gallons per minute) of water from a well depends upon the permeability of the rock. Where permeable materials are near land surface, a shallow well may be adequate. Elsewhere, such as where clayey material directly overlies bedrock, a deep well extending into bedrock may be needed.

Private Wells

A schematic of how a typical single-home domestic water well works.

Credit: U.S. Environmental Protection Agency

Many people in the United States and worldwide supply their own water for their homes, often in more rural locations that don't have large public-supply water systems to supply water. Here is a basic diagram showing how these wells function. Although this diagram shows a single home, large wells that supply more customers work generally the same.

WELL COMPONENTS

Below are descriptions of the basic components found in a private water well. ( Source: National Ground Water Association)


Probably repetitive, but oh God the smell.

Question: if I had a diva cup smell mishap, will my lady parts smell bad if I clean appropriately and don't use it? I need info and advice on my personal smell, not the cup. I have been working and travelling for 3 months, and in two fucking days I'm supposed to have passionate reunion sex with my man friend.

I've been using a diva cup for about a year and a half. I'm 31, have a light, regular period, and only have had a little trouble with leaking if it's folded. I've never had bv, a yeast infection, a uti, or anything like that. I've actually never had any strong vaginal smell, let alone stink, even after days with out real bathing (working in back country, I'm clean when I have plumbing). I've left it in for 24, ok, max of 36 hours, (gross I know) accidentally maybe 2 other times. No smell, no irritation. Otherwise I empty and rinse it a minimum of twice a day. Sooo this evening something changed.

I took out the cup after leaving it in longer than usual, 18 hours, not the longest ever, due to a long work shift, and I literally threw up when I realized the awful smell was coming from the cup. So i had to clean up vomit and rotten meat smelling blood from my sink. Rad. I threw it away. Fuck that. I've saved enough waste to justify that hopefully. End of my cycle anyway, and I have a pair of thinx I prefer to sleep in, and should be done by now.

Will my parts continue to stink? They don't seem to smell now, but I'm scared it will still smell in a few days when. uhh. it really counts. I'm also really worried about using a cup again. I CANNOT tolerate a smell like that.

Experience, advice? Please no cleaning of the cup tips, I've Google the crap out of those.

I need to know if this will continue to happen, and if there's a good way to be "fresh" SOON. I won't douche and I won't use vgasil or any of that poison. I am honestly panicking. It is my favorite body part, and I'm scared the whole little ecosystem of my crotch is fucked up now.

If the smell is literally strong enough to make you vomit you need to go to the doctor. Do not pass go do not have sex do not think twice.

Perhaps you had a miscarriage, an ectopic pregnancy, an abcess of some sort - who knows, but you NEED to see a doctor.

Honestly, you are leaving it in too long. I find mine smells after 18 hours too. I try to leave it no longer than 12. It has happened to me a few times because I have ADHD and I forget things (I think it's probably less bad than forgetting about a tampon.) I have been using a cup for over 6 years now. One other time it happened, when it was particularly bad, was when I was towards the end of my period and Iɽ had a bath. I emptied the cup just before the bath so didn't think to afterwards. My vagina must have sucked up some bath water which got caught in the cup and the bath water with the gross blood together made some unholy stink-perfume combination which was just awful. So always empty the cup immediately after swimming or bathing too. It doesn't always smell when left too long but every time I've had a smell, it's when it's been left longer than it should have been.

If you have an accidental too-long usage which causes a smell, you'll need to disinfect the cup before using it again, which means washing with soap and then boiling it or using sterilising liquid. Clean thoroughly. Poke through the holes with a needle or an old toothbrush. Check the stem if you have a stem, and any ridges for grip. Menstrual blood is more mucousy than liquid so it can cling to little nicks and corners in the cup. It's also possible that improper care of the cup between cycles could mean that it harbours bacteria which could then multiply in the nice warm protein-y, blood-temperature environment of the cup and (again my issues) I admit I don't always clean it completely between cycles. Sometimes I just rinse it really really well, and it's normally fine. But if you want to be sure it's better to disinfect between uses.

IME it doesn't affect the smell of your vagina directly. At least my husband has never complained and he did once walk into the bathroom when I had a cup full of grossness and really gagged. He's pretty blunt and he would tell me if I had a funky odour down there for sure. Your vagina is self cleaning and it knows how to take care of itself.


Middle School Science Fair Ideas

Middle school is where kids can truly shine at the science fair! Kids should try to come up with their own project ideas, based on topics that interest them. Parents and teachers may still need to help with posters and presentations, but middle school students should have control of the project. Examples of middle school science fair ideas include:

  • Examine food labels. How does the nutritional data for different brands of the same food (e.g., microwave popcorn) compare?
  • Is laundry detergent effective if you use less than the recommended amount?
  • How permanent are permanent markers? Are there chemicals that will remove the ink?
  • Can a saturated solution of salt still dissolve sugar?
  • Do green bags really preserve food longer?
  • Are goldfish water chemicals really necessary?
  • What shape of ice cube melts the slowest?

Staining Science: Make the Boldest, Brightest Dye!

Introduction
Have you ever wondered about the materials that make up your clothes and why some look and feel different from others? The clothes you wear are made of fibers that come from many different sources. Some fabrics are made from natural fibers and others are from manufactured, or totally synthetic, fibers. In this activity you'll explore how well different fiber types can be dyed using fiber-reactive dye. Aren't you just dye-ing to find out which fabric works best?

Background
From woven mummy shrouds in ancient Egypt to the ornate ball gowns ladies wore in the Victorian era to the tie-dyed shirts that gained popularity in the 1970s, dyed cloth has played an important role in human culture. Its production has also changed over time. Early dyes were made using natural resources, like plants, berries, minerals and seeds. The cloths, just like the dyes, were made from a natural resource&mdashsuch as cotton, linen, wool or silk. Cotton and linen fibers are all formed from cellulose, the main component of plant cell walls. Wool and silk are animal-protein-based fibers.

Later, as advancements were made in chemistry and manufacturing, people learned to make other fibers, including polyester, nylon and rayon, which are known as synthetic fibers. Today's dyes are also different&mdashthey are now often made with artificial chemicals. By understanding how the molecules of dye react with the different types of fibers, chemists can design many vibrant and color-fast dyes (which means that they won't fade or run) and figure out on which fiber types they work best.

Materials
&bull Three different types of white fabric samples: such as linen, cotton&ndashpolyester blend, 100 percent polyester, 100 percent cotton, wool, rayon, silk and nylon. Collect enough to make at least one 10-inch by 10-inch square of each type. Preferably select one natural fabric, a synthetic one and one that is a blend of both. Scraps from old pillow cases, sheets, rags or unwanted clothes can make good sources&mdashjust be sure they are okay for discard and that you know the fabric type. Otherwise, small pieces can be purchased from a craft or fabric store.
&bull Ruler
&bull Scissors
&bull Permanent marker
&bull Newspaper or rags
&bull Measuring cup, which will not be used for cooking afterward (If unavailable, create a discardable plastic cup measurer. To do this, measure out one half cup of water, pour it in the disposable cup and mark the top of the water with a permanent marker. Dump out the water and repeat with one full cup. Use this marked container as your measuring cup.)
&bull Laundry detergent
&bull Safety goggles or protective glasses
&bull Rubber gloves
&bull Clean glass jar, at least 10 fluid ounces. It should not be used to consume food or beverages afterward
&bull Measuring teaspoon and tablespoon. (They should not be used for cooking afterward. If unavailable, measure one teaspoon of water into a disposable plastic spoon and note the quantity. Repeat with the tablespoon.)
&bull Fiber-reactive dye powder, such as Tulip Permanent Fabric Dye or Procion Pro MX Reactive Dye, often available at a craft and or fabric store. Use a bold color, like red, blue or green
&bull Salt
&bull Water
&bull Sealable plastic bag, one-gallon size
&bull Timer or clock
&bull Soda ash or Arm & Hammer Super Washing Soda
&bull Plastic container that can hold four cups comfortably. (It should not be used for food or beverage afterward.)
&bull Old clothes to wear that can get stained

Preparation
&bull Cut at least one 10-inch by 10-inch square out of the each fabric sample (linen, cotton-polyester and 100 percent polyester, for example).
&bull Use the permanent marker to label each square with its fabric type. Because the permanent marker may leak through some types of fabric, if you are not working on a surface that can be stained, label the fabrics on top of newspaper or rags.
&bull Prewash the fabric squares by putting them in a normal clothes washing machine with laundry detergent. Wash using hot water, if possible. Allow the fabric squares to air dry.
&bull Before opening the dye powder packet, cover the area you will be working on with newspaper or rags so that you will not stain it. You might want to work outside to avoid staining something. Also put on clothes that you would not mind staining.
&bull Dyes often contain soda ash (sodium carbonate), which is caustic. Wear goggles and gloves when mixing the dye solution, mixing the soda ash solution and rinsing the fabric samples after dyeing.

Procedure
&bull Put on gloves and safety goggles.
&bull Put two teaspoons of powdered dye, one tablespoon of salt and one cup of warm water into the glass jar. Mix thoroughly. How does the dye look?
&bull Wet the fabric squares with water and place them in the sealable plastic bag. Carefully pour the dye solution into the bag then add one half cup of water. Seal the bag, trapping as little air as possible. How does the fabric change when the dye is added?
&bull Let the bag sit for 20 minutes. Every couple of minutes, gently squeeze the bag to coat all of the fabric samples.
&bull While the fabric is soaking, mix one tablespoon of soda ash (or Arm & Hammer Super Washing Soda) with two cups of warm water in the plastic container. Break up any hard pieces that form.
&bull After the fabric is done soaking, carefully open the plastic bag and add one half cup of the soda ash solution. Reseal the bag, trapping as little air as possible.
&bull Gently squeeze the bag to mix the soda ash, dye and fabric. Let the bag sit for one hour, gently squeezing every 10 minutes or so.
&bull With gloved hands, reach into the bag and retrieve the fabric samples and place them on a surface where they will not stain anything. Carefully dump the contents of the bag into a sink (pouring directly into the drain so as not to stain any of the sink area).
&bull Rinse the fabric until the water runs clear. When you are done handling the rinsed fabric and disposing of the soda ash solution, you can remove your goggles and gloves. Wash the fabric samples in the washing machine just as you did before (but not with any other clothes). Allow the samples to air dry.
&bull Once they're dry, how do the fabric samples look? Did some types of fabric become dyed to a darker shade than others? Did some types not absorb much dye at all?
&bull Extra: In this activity you tested how well different fabric samples dyed using a fiber-reactive dye. But there are many other types of fabric you could test dyeing, and they may react differently. How well do other types of fabric become dyed with a fiber-reactive dye?
&bull Extra: Before synthetic dyes were created, humans used natural dyes. Do some background research and pick one or more natural dyes to try in this activity. You will probably want to use relatively safe dyes, such as turmeric or berries. Be just as careful with these around other surfaces and materials, as they also stain easily. Do some natural dyes work better than others? Does it depend on the type of fabric used?

Observations and results
Did coarse, natural fabrics, such as linen or 100 percent cotton, become dyed the darkest shade? Did synthetic fabrics, such as polyester or rayon, remain nearly white? Did fabrics that were a blend of natural and synthetic fibers become noticeably dyed, but not quite as dark as fully natural fabrics?

Cotton and linen fibers are both natural fibers made from cellulose, a compound found in plant cell walls. Fiber-reactive dyes form permanent covalent chemical bonds with cellulose, making this dyeing process a relatively permanent one. Polyester, however, is a synthetic fiber that does not react with fiber-reactive dyes in this way and cannot be effectively dyed using them. For polyester to be successfully dyed a different category of dyes must be used&mdashspecifically dispersion dyes, and a great deal of heat has to be applied during the dyeing process. In this activity you probably saw that synthetic fabrics were not effectively dyed, remaining nearly white, whereas the natural fabrics dyed the darkest shade and the blend fabrics were not quite as dark as the natural fabric (depending on the percentage of natural and synthetic fibers in the fabric).

Cleanup
You can safely pour the extra soda ash solution down the drain, flushing with water. Do not use the measuring cup, measuring spoons, plastic container or glass jar for cooking or food afterward. Carefully rinse and then recycle the plastic sealable bag.

More to explore
Fiber-Reactive Dye Chemistry, from Dharma Trading Co.
About the Dyes, from Paula Burch's All About Hand Dyeing
How to Make the Boldest, Brightest Tie-Dye!, from Science Buddies

This activity brought to you in partnership with Science Buddies


A Really Long Straw

Introduction
Have you ever used a crazy straw? Some spiral their way up. Others have fancy colors or decorations. Some are thin and others are wide. But just about all of them leave you sipping your drink from about the same distance. Why? Wouldn't it be fun to poke your head out of an upstairs window and secretly take a sip from a drink way below? Would it even be possible? With this activity, you&rsquoll see if you can set your own record for the longest working straw!

Background
Sipping a drink through a straw might seem simple. But you are actually using some fancy air pressure changes to move your beverage. The sipping action occurs when you lower the air pressure in your mouth, which allows the atmospheric pressure to push the liquid up the straw.

Does that sound bizarre? Here is a little more explanation: The atmosphere is a massive layer of air. The weight of all that air is constantly pressing on us and on the things around us. At sea level, this invisible pressure is approximately 14.7 pounds per square inch. That is like having the weight of a bowling ball sitting on each square inch or five bowling balls pressing on the liquid filling a two-and-a-half-inch-diameter glass. Put a straw into liquid and the liquid will enter the straw until it reaches the same level as the liquid outside the straw. The liquid in the straw and around it is being pushed down by the air above it in a similar way, so they reach about the same level.

But it gets interesting when you remove some air from the straw. Suddenly, there is less air pressure inside and liquid is pushed up the straw. The more air you remove from the straw, the higher the liquid will be pushed into it.

Do you think there is a limit to how high the liquid can rise in a straw? This activity will help you make a very large &ldquomega-straw&rdquo and test it out!

  • A package of plastic straws (at least one dozen), preferably those with a bendable part
  • Scissors
  • Ruler
  • Tape
  • Drinking glass filled with water
  • Level surface that can get wet (or if not, something to protect it)
  • Sturdy chair or table on which to stand

Preparation

  • Have an adult help to cut two half-inch slits, across from one another, lengthwise in one end of a plastic straw. These cuts will help you slip the end of one straw over another one.
  • Prepare 10 more straws in a similar way until you have enough for a superlong mega-straw! (You can also come back to these steps during the process in case you need more straws for your mega-straw.)
  • Slip the cut end of a prepared straw over the end of an unprepared straw.
  • Wrap the area where the straws overlap with tape so you have an airtight seal. Do not hurry a good airtight seal will help you avoid trouble later. Why do you think a secure, airtight seal is essential for your mega-straw to function well? (Hint: When you drink with a straw, you must remove air from it.)
  • To test your extralong straw, put a glass of water on level ground. (Be sure to place something down to protect your level surface or use one that can get.) Now hold your straw vertically or close to vertically and try to drink with it. Does water reach your mouth?
  • If little or no liquid enters the straw, check the seal where you joined the straws. Is it airtight? If not, add tape or undo and redo this connection. If the seals at all joints seem airtight, check for holes in other areas of your mega-straw and seal them with tape.
  • Play around with your first mega-straw. Suck lightly to remove a little air from the straw then suck hard to remove more air. Observe each time how high the water rises in your mega-straw. What happens if you suck up more air? Why do you think this happens?
  • Time to add on! Attach another prepared straw to your mega-straw in a similar way and put your lengthened mega-straw to the test. Remember to hold your straw vertically or close to vertically during your test. Is your new straw functioning properly? Does it get harder to suck up water?
  • Keep adding prepared straws and testing after each addition. You might have to carefully stand on a chair to test your growing mega-straw. Does it become harder and harder to suck up water as you stand higher and higher above the glass?
  • Once you have connected a few straws together and it becomes a little challenging to drink with the straw, test your mega-straw at different angles. In addition to holding the straw vertically, test it at an angle about halfway between horizontal and vertical (approximately 45 degrees) as well as by holding it as close to horizontal as possible. Note that you might need to add more water to your glass to test a fairly horizontal position. Is there a difference in effort needed to suck up water? If so, rank the straw positions in descending order: 1 being the hardest to suck up water, or needing most effort 3 being the easiest, or needing the least effort. Note that you did not change the distance over which the water was transported the straw stayed the same length. What did you change that might have created a difference in effort needed?
  • Pause a moment and think about how the difference in height between your mouth and the glass changed depending on the angle at which you held the mega-straw. Rank the methods in descending order of difference in height between your mouth and the glass: 1 being the position with the most height 3, the position with the least height. Do you see a correlation between the difference in height and the effort you needed to suck up water?
  • If you have bendable sections in your straw, test what happens if you keep the height of your glass and your head the same but change the way you bend the mega-straw. Try a straight mega-straw and a mega-straw with one or several kinks. How do the levels of effort compare now that you keep the difference in height unchanged?
  • Build on. How many straws can you connect before you can no longer drink from it if held vertically? Do you think there is a limit or would you be able to build on indefinitely, as long as you could test it from higher and higher places?
    Extra: Test with different types of straws, such as ones that are wide or very narrow. Would one type be more suited to make a mega-straw?


Observations and results
When you suck air from the straw, less air pushes on the water inside the straw than on the water outside of it. This imbalance causes more water to be pushed into the straw. The water will rise until the pressure created by the water column in the straw equals the air pressure difference.

Remove more air, and a bigger difference in air pressure will cause the water level to rise even higher into the straw. As soon as the water reaches the height of your mouth, you can drink.

Your lung power determines how much air you can remove. Some will have difficulty with a three-foot straw whereas others can successfully drink standing eight feet above their drink!

There is a limit though. If you could create a complete vacuum in your mouth by removing all the air, the water could rise about 30 feet high. It's not possible, however, to create a complete vacuum in the human mouth, so usually people reach their straw-slurping limit at a much lower level!

Note that it is mainly the difference in height the water needs to overcome that counts, not the total length the water needs to travel in the straw. Holding your straw almost horizontally will allow you to suck up water over a very long distance.

More to explore
Would a Straw Work in Space? from Science-Based Life
How Do Drinking Straws Work? from Indiana Public Media
Under an Ocean of Air Pressure, from University of Illinois Extension
Atmospheric Pressure, from ScienceOnline

This activity brought to you in partnership with Science Buddies


How well do Eppendorf cups seal? - Biology

PLEASE REVIEW OUR GUIDELINES BEFORE SUBMITTING YOUR PLASMID(S) !

To ensure the successful sequencing and assembly of your plasmid(s), all guidelines for sample preparation and submission must be addressed. Please contact us if these requirements cannot be met so we can work with you on identifying a solution on a case-by-case basis.

Sample Requirements:

Please submit CIRCULAR DNA only! Linear DNA (such as amplicons and restriction fragments) have to be submitted for our Complete Amplicon Sequencing service, as linear DNA samples require a slightly modified assembly approach.

To ensure suitable sample quality, the use of a column-based purification method is preferred.

Contamination with bacterial genomic DNA must be avoided as it is the most common reason for assembly failure.

The purified plasmid DNA should be resuspended in nuclease-free water, in 10 mM Tris-HCl (pH 7.5-8.5), or in LTE Buffer (10 mM Tris-HCl, pH 8.0, 0.1 mM EDTA).

The plasmid DNA isolate must be diluted to a final concentration of 40-65 ng/µl.
Please note: The DNA concentration should be determined by spectrophotometry. Our recommendations for accurately determining DNA concentration can be found here.

Our automated workflow requires the submission of 35 µl of the diluted plasmid DNA.

Tube Orders:

If you are submitting your samples in tube format, please use standard 1.5 ml flip-cap Eppendorf-type tubes.
Please note:Our operational setup does not accept 0.2 ml tubes, 0.5 ml tubes, strip-tubes, and screw-cap tubes.

Please label the top of the lid of each tube - as clearly as possible - with a maximum of 5 alpha-numeric characters (for example: 5B001). We strongly recommend to hand-write each label using a permanent marker. Self-adherent stickers might fall off during shipment, thereby making sample identification impossible.

We recommend wrapping tubes with Parafilm to prevent samples from drying.

Tubes should be submitted in order as listed on the submission form (not randomly placed, and not loose/unracked).
Please note: If you are using one of our remote drop-off locations, please rack your tubes in one of the provided sample boxes and attach order form with a rubber band.
If for some reason no boxes should be available, please tape tubes to the order form (or a separately attached sheet) in the same order as listed on your order form. You may also use any other type of rack/box designed to hold 1.5 ml tubes.

If your order contains 48-95 samples or is a full 96 sample plate, please use the plate format to receive a discount (see plate guidelines below).

Plate Orders. These guidelines apply to both the 48-95 and full 96 sample plate discounted rates

If you are submitting your samples in plate format, please use only V-bottom PCR plates.

We recommend the use of semi-skirted (or skirted) plates to prevent the PCR plate from bending during transit, which could result in loosening of the seal and subsequent sample loss and cross-contamination.

Please arrange your samples horizontally (in rows) in the PCR plate. Proceed from well A1 to A12, from B1 to B12, from C1 to C12, etc.

We accept partial plates but please do not leave any empty wells between samples, and please do not leave any empty spaces between samples on the order form.

No discounted rate will be applied for orders with fewer than 48 samples, even when submitted in plate format. Multiple orders cannot be combined to receive either the 48-95 or the full 96 plate discount.

The order form must match the order and position of samples in the PCR plate.

Please label the plate as clearly as possible - with a maximum of 5 alpha-numeric characters (for example: 5B001).

Tightly seal your plate(s) with an adhesive sheet/foil to prevent samples from drying and/or cross-contamination.

Sample Shipment:

We are currently offering our Complete Plasmid Sequencing service for individual samples and full plates once a week, beginning each Wednesday. The deadline for sample arrival at the Core Facility (38 Sidney St. Cambridge) is 4pm. If you should miss this cutoff time, your samples will be entered into the queue and processed during the following cycle.

Samples may be submitted early and they will be stored at the core under the appropriate conditions until the Wednesday start date. Full plates will be processed on a first come, first serve basis and the turnaround time will depend on the current demand. We ask researchers to notify the NGS Team Manager ahead of time to allow us to plan accordingly.

Please submit your sample(s), including a hard copy of the completed order form, by using one of our remote dropboxes (please see here) or by delivering it personally to our core facility.

If remote or direct sample drop-off should not be an option for you, please ship your samples, including a hard copy of the completed order form, via a courier delivery service of your choice (for example, overnight shipment via FEDEX, UPS, etc.) to our core facility. Samples can be shipped at ambient temperature.

Shipping Tubes:

Unfortunately, we often receive sample tubes that were damaged during shipment (cracked or shattered tube, sample loss due to leakage or evaporation). Therefore, we strongly recommend sealing the sample tube with Parafilm and further protecting it with bubble wrap or several layers of Kimwipe tissue. Another option is to place the sample tube into a secondary container such as a Falcon tube or small cardboard or plastic box.

Shipping 96-well Plates:

Samples should be arrayed in a 96-well (semi-skirted or skirted) plate. To prevent sample loss and/or cross contamination, we recommend tightly sealing all wells of the plate with Microtube Caps. PCR Tube Strip Flat Caps (Eppendorf cat# 0030124847 or VWR cat# 75874-710) work well for most plates. Our everyday experience tells us that plate foils/plastic seals can partially lift off or even entirely detach during transit dependent on the shipping conditions (heat, air pressure, humidity, etc.). Please place your plate in a corrugated box for maximum protection.

Shipping Address:

MGH CCIB DNA Core Facility
38 Sidney Street / Suite 100
Cambridge, MA 02139
U.S.A.

IMPORTANT: Please note that we are not receiving samples on Saturdays and Sundays or on official holidays.



Comments:

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  3. Jenyd

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  4. Nara

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