Thermal Mechanical Stretching to Imprint Pores Morphology of Nitrocellulose Membrane for Immuno-sensing Application

Performance of membrane such as the lateral flow wicking time and protein binding ability are important to generate consistent results for diagnostics purposes. Different diagnostic kit need different surface properties of membrane, structures and dimension. This work evaluates the feasibility of controlling membrane pores morphology through thermal-mechanical stretching. Results shows that membrane fabricated using longer nitrocellulose (NC) polymer chain length produced smaller pores with lower porosity (56%). Thus, it took longer time of 32s to migrate the testing liquid along the membrane strip. By having higher membrane’s porosity (72.3%), the membrane synthesized using shorter NC chain length exhibited faster wicking time, which is 3 times faster (wicking time of 8s) than that of the membrane produced with longer NC chain length. In terms of the thermal-mechanical stretching effects, the stretched membranes (both uniaxial and biaxial directions) had demonstrated improved immunoassay performances compared to the unstretched membrane. Specifically, uniaxial stretching is preferable than biaxial stretching configuration, due to the great improvement of lateral wicking time (22% faster) without jeopardize the membrane protein binding capacity (only 1.7% decrement), in relative to the unstretched membrane. This study provides some interesting insight on the physical membrane modification to provide better performance in immunoassay applications.

Mutational burden on circulating cell-free tumor-DNA testing as a surrogate marker of mismatch repair deficiency/microsatellite instability and/or response to immunotherapy in patients with colorectal cancer.

e15066 Background: Circulating cell-free tumor-DNA (ctDNA) testing (‘liquid biopsy’) is increasingly being employed both in clinical trials as well as clinical practice. We aimed to contrast and compare the differences in the number of somatic mutations observed on ctDNA testing between mismatch repair deficient/microsatellite instability-high (dMMR/MSI-High) versus mismatch repair proficient/microsatellite stable (pMMR/MSS) colorectal cancers (CRC). Methods: We had 20 patients at Mayo Clinic Florida that were dMMR/MSI-High with testing through the commercially available platform (Guardant360) that uses a 73-gene panel. Median numbers of somatic mutations were compared between the 2 subset of CRC. Results: Patients with dMMR/MSI-High CRC had a median of 8 mutations (range: 2-15) versus a median of 4 mutations (range: 1-22) in pMMR/MSS patients, p-value of 0.001. Similarly, the mean number of somatic mutations were 7.47 (S.D. ± 4.15) versus 5.02 mutations (S.D. ± 3.83) in patients with dMMR/MSI-H and pMMR/MSS, tumors respectively. Though it is simplistic, we could still potentially identify patients who may be candidates for immunotherapy by gauging the mutational burden reported (Table). Furthermore, on serial testing, decline in mutational burden as early as few weeks into therapy was predictive of response later on imaging. Conclusions: Analysis of number of somatic mutations on ctDNA testing can be complementary to MMR/MSI-testing, especially in situations when tissue is not available or safe to obtain. This can also be of value in predicting and/or following response to immunotherapy. The utility of this may go beyond CRC in identifying patients who may benefit from immunotherapy. [Table: see text]

Analysis of the External Conditions Affecting on the Cavitation Resistance of a Steel

The aim of this study is to analyze the effect of cavitation erosion test conditions on the surface resistance of medium carbon steel. The ultrasonic vibratory specimen system was used to perform the experiments under the laboratory conditions. The vibratory frequency and the displacement amplitude were 20 kHz and 20 μm, respectively. In design of experiments, four various cavitation behaviors have been studied based on four cavitation test conditions corresponding to those behaviors. These conditions can be summarized as follows: (1) the usage of water as a testing liquid; (2) replacement the water with 3.5% NaCl solution; (3) applying a certain voltage to cause a combined electrochemical action working simultaneously with the water; and (4) applying the same voltage by using the 3.5% NaCl solution instead of water. The obtained results showed that the mass loss differs by test modes applied.

STUDY OF DIFFERENCES BETWEEN REAL AND EFFECTIVE HEAT TRANSFER COEFFICIENTS TO PROVIDE CORRECT DATA ON TEMPERATURE FIELD CALCULATIONS AND COMPUTER SIMULATIONS DURING HARDENING OF STEEL

The paper analyses contemporary methods and probes for testing liquid media used as a quenchant in heat treating industry. It is shown that lumped-heat-capacity method, often used for testing liquid media, produces big errors during transient nucleate boiling processes due to incorrect calculation condition caused by use effective heat transfer coefficient (HTC). The effective heat transfer coefficients (HTCs), utilized for this purpose, are almost seven times less as compared with real HTCs that results in incorrect calculation the value of Bi. Instead of lumped-heat -capacity method, a general cooling rate equation is proposed for HTC calculation. It is underlined that effective HTCs can be used only for approximate core cooling rate and core cooling time of steel parts calculations. For investigation cooling capacity of liquid quenchants, including initial heat flux densities, HTCs and critical heat flux densities, high developed technique of solving inverse problem should be used based on accurate experimental data generated by testing liquid media with the Liscic/Petrofer probe or other similar technique.