Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit

Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing.

Conservative surgery in the management of a benign ovarian cystic teratoma presenting as a rectal mass: a case report

Ovarian cystic teratomas constitute 10-15% of all ovarian tumours and are the most common ovarian neoplasms found in adolescence and during pregnancy. Nevertheless, ovarian cystic teratomas have also been described in patients aged 1-91 years. We report an unusual case of a benign ovarian cystic teratoma presenting as a rectal mass that was managed surgically using radical resection by a multidisciplinary team. This case report highlights the importance of preoperative investigations including colonoscopy and radiological investigations. A dedicated pelvic radiologist/pathologist and the involvement of a multidisciplinary team at the time of initial diagnosis and a gynaecologist and colorectal surgeon at the time of surgery will lead to an accurate diagnosis and the most appropriate treatment. Although rare, erosion of an ovarian dermoid into the rectum should be considered in young women who have an atypical presentation and are found to have a lesion in the rectum with biopsies indicating benign pathology.

Rice dehydrin K-segments have in vitro antibacterial activity

Dehydrins are groups of plant proteins that have been shown to response to various environmental stimuli such as dehydration, elevated salinity, and low temperature. However, their roles in plant defense against microbes have not been demonstrated. In an attempt to discover plant antimicrobial proteins, we have screened a rice cDNA library and isolated several cDNAs coding for dehydrins. Protein extracts from Escherichia coli expressing these cDNAs were tested for their activity against Gram-positive bacteria (Bacillus pumilus, B. subtilis, Staphylococcus aureus, and Sarcina lutea) and Gram-negative bacteria (Escherichia coli and Xanthomonas oryzae pv. oryzae). The results indicate that the crude protein extracts exhibited antibacterial activities against the Gram-positive bacteria. However, dehydrins purified by immunoaffinity chromatography were not active against the bacteria. To pinpoint the dehydrin peptides that were responsible for the bactericidal activity, we expressed DNA sequences coding for truncated dehydrins containing either K- or S-segment and found that K-segment peptides, and not S-segment, were responsible for the antibacterial activities against Gram-positive bacteria. Antibacterial assay with synthetic K-segments indicated that the peptides inhibited growth of B. pumilus with minimum inhibition concentration and minimum bactericidal concentration of 130 and 400 μg/ml, respectively.