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Dextran, a polysaccharide made from glucose, is widely used in the medical field for treatment of shock, as an antithrombotic agent, to reduce blood viscosity, and as an anticoagulant. The two most common forms are dextran 40 and dextran 70 (the 40 and 70 refer to their molecular weights, nominally 40,000 and 70,000 g/mol).

The USP monographs for dextran 40 and 70 describe a specific gel permeation chromatography approach that differs in success criteria from other GPC methods, and requires a unique GPC system setup and data analysis method. To qualify a dextran formulation under these USP guidelines, the material must be tested by this GPC method.

A calibration curve is constructed with dextrose and five dextran standards of known molecular weights, using either a Gauss-Newton method or the Nilsson-Nilsson method to determine the constants in the expression below for each of the standards based on their reported molecular weights M_i.

Mi = b₅ + exp(b₄ + b₁Ki + b₂K_i² + b₃K_i³)

Each of the standards must meet a rigorous accuracy check to ensure the GPC system is adequately set up to test the specific dextran samples and to ensure they meet the requirements of the USP monographs. Once the equipment is properly validated by this method, the samples can be tested.

CPG is experienced in this USP test method for dextran GPC analysis. Contact one of our scientists for more information.

A CPG twist on a holiday classic, with happier results

Total ion chromatogram of 4 chocolate samples showing peaks of caffeine and theobromine in water extraction.

ISO and ASTM are drafting a new standard on qualification of polymeric materials used for additive manufacturing using powder bed fusion (ISO/ASTM DIS 52925:2020). This standard is focused on polyamide 12 and 11, but the standard may be applicable to other polymeric materials.

The standard discusses the following test methods:

1. Particle size
2. Residual monomer
3. Relative humidity
4. Melt flow index
5. Molecular weight (either by GPC or dilute solution viscometry)
6. Melting and crystallization temperature by DSC

These tests are all performed by Cambridge Polymer Group, and can be used to qualify new material or requalify used material. Contact us for more information.

The ASTM workshop on Reprocessing Personal Protective Equipment (September 9-10, 2020, virtual workshop) is looking for presentations on the following topics:

• Methods/guides/practices to address reprocessing single use PPE and reusable PPE (including N95 respirators, personal face masks, protective clothing and coverings, etc.):

• Current issues with decontaminating single use PPE
• Cleaning
• Index matching
• Collection and distribution
• Loss of efficacy
• Degradation of components
• Tracking number of re-uses
• Cleaning/decontamination/sterilization
• New sterilization/disinfection methods – chlorine dioxide, etc.
• Assessing performance of the reprocessed device, including feedback from healthcare providers who have used reprocessed devices
• Effects of bioburden on re-use, for disinfection and perception
• Standards used
• Existing: ASTM, NIOSH and other
• Include limitations, such as multiple decontaminations
• Novel test methods introduced by researchers during the COVID-19 outbreak
• Methods/guides/practices for producing and or assessing performance of devices and device components that are in short supply
• e.g. masks, respirators, and face shields
• Both traditional device designs and novel designs using materials that are at hand
• Redesigning single use PPE for potential re-use during surges
• Discussion of FDA Emergency Use Authorizations (EUAs),
• For current EUAs, the impact on supply chain and on products/methods covered by current EUAs.
• Considerations needed to continue product access upon EUA expiration including impacts on the supply chain and on products/methods covered by current EUAs.
• Share perspectives on how existing standards helped you in addressing device shortages or how they could have been of more assistance

Abstract Submittal

To participate in the workshop, your 300-word abstract is due no later than July 26, 2020. Please see the ASTM symposium page for submission instructions.

Australian thorny devil 

Lizard Surface Energy Wetting

The Australian thorny devil (meloch horridus) is a desert-going lizard that has developed an impressive application of transport phenomenon to make the most of a limited source of water in the arid regions it inhabits.[1] The lizard has a skin surface that contains a continuous series of micro-channels that are capable of transporting water by capillary action towards the lizard’s mouth. As the lizard crawls over and under vegetation that contains droplets of dew, it effectively collects this water all over its body, allowing it to drink on the run. The lizard’s mouth, suitable for eating ants, is not adapted to drink water directly, necessitating this curious mode of drinking.

Capillary Transport in Nature

Capillary transport is quite common in nature. It is the mechanism by which water is moved from the roots of trees up to its leaves.  It is the means that our eyes drain tear fluid through the narrow tear ducts in our eyelids. This ability results from the attractive nature that water molecules have for each other, termed the forces of cohesion. This cohesion leads to surface tension, or the resistance of the surface of a liquid to an external force, such as a solid object penetrating the liquid. This tensile force causes the liquid to form a meniscus when placed in a narrow capillary, and if sufficient adhesion occurs between the water and the capillary wall, the water will be pulled along in the capillary, even overcoming the force of gravity if the capillary diameter is sufficiently small.

While this mode of drinking may appear convenient, one could argue that the quaffable benefits of the thorny devil's capillary-driven drinking mechanical are outstripped by the social liability of its crenulated dermis. But from a surface science point of view, the thorny devil has arrived at a low energy, high efficiency method of harvesting water.

For more information on surface energy measurements, contact Cambridge Polymer Group or visit our website.

 

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CPG is now fully open and able to work on ALL projects; we are no longer limited to COVID-19 response or projects essential for medical emergency staff. Turnaround times may still be affected due to the need to social distance.

Cambridge Polymer Group is in compliance with Massachusetts Governor Baker's May 18th re-opening schedule. CPG has been deemed an essential business, and has implemented all safety precautions stipulated by the re-opening order, as well as additional safety measures.

CPG COVID-19 Visitor Policy

Cambridge Polymer Group is committed to providing a safe environment for our employees and visitors. For the protection of all, we’ve implemented the following requirements:

Upon entering the facility, all persons must:

• Have a face mask or covering
• Undergo a temperature and symptom screening
• Promptly wash hands
• Comply with social distancing practices at all times

While in the laboratory, all persons must:

• Wear proper personal protective equipment including gloves and safety glasses
• Wash hands upon exiting

In addition to these requirements, Cambridge Polymer Group has increased the frequency of cleaning and disinfection of the workplace. These policies and procedures have been implemented to reduce transmission risks and protect our workforce. Your cooperation is appreciated.

Dropping Off Samples

If you are dropping off samples and do not need to enter our office or lab space, follow these steps:

1. Notify your CPG contact of the time you intend to drop off samples.
2. Enter the 56 Roland Street building at the North Lobby entrance. Take the stairs or the elevator to the third floor. Follow the signs to Cambridge Polymer Group.
3. Leave your samples and SSF form on the stool to the left of CPG's door, under the USPS/UPS/Fedex sign. We will retrieve them after you leave.

Best wishes,

Cambridge Polymer Group