Applicability of the Meniscus-Removal Method for Q-Band Liquid Characterization in Semi-Open Waveguide Cell.

We present the broadband transmission-reflection meniscus-removal method for liquid characterization in a semi-open rectangular waveguide. The algorithm utilizes 2-port scattering parameters measured with a calibrated vector network analyzer for three states of the measurement cell: empty and filled with two liquid levels. The method enables the mathematical de-embedding of a symmetrical sample of a liquid, not distorted with a meniscus, and provision of its permittivity and permeability, as well as its height. We validate the method for propan-2-ol (IPA), a 50% aqueous solution of IPA, and distilled water in the Q-band (33-50 GHz). We investigate typical problems for in-waveguide measurements, such as phase ambiguity.

Meniscus-Corrected Method for Broadband Liquid Permittivity Measurements with an Uncalibrated Vector Network Analyzer.

We present a novel broadband permittivity characterization method for liquids measured in a semi-open vertically oriented test cell with an uncalibrated vector network analyzer. For this goal, we utilize three scattering matrices measured at different levels of liquid in the cell. With mathematical operations, we remove the effects of systematic measurement errors caused by both the vector network analyzer and a meniscus shaping the top of the liquid samples in such a type of test cell. To the best authors' knowledge, this is the first of such a calibration-independent method dealing with meniscus. We verify its validity by comparing our results with the data available in the literature and with the outcomes of our previously published calibration-dependent meniscus removal method (MR) for propan-2-ol (IPA), a 50% aqueous solution of IPA and distilled water. The new method yields results comparable with the MR method, at least for IPA and the IPA solution, revealing, however some problems when testing high-loss water samples. Nevertheless, it allows one to cut down on expenditures in the system calibration engaging skilled labor and expensive standards.

Complete Meniscus Removal Method for Broadband Liquid Characterization in a Semi-Open Coaxial Test Cell.

We present a new technique for broadband liquid characterization using a semi-open, vertically oriented test cell that is measured with a calibrated vector network analyzer in three states: the empty one and filled with two different volumes of the liquid under test. Using the measurements, we de-embed a transfer matrix representing a volume increment of the liquid sample and determine its column height with a novel closed-form formula. Thanks to the de-embedding, the method enables one, for the first time, to completely remove effects caused by a reproducible meniscus forming the top surface of a liquid tested in the cell and determine not only the propagation constant, but also characteristic impedance of the liquid sample, from which its permittivity and permeability are calculated. The results are highly consistent, because all the measurements are performed without disassembling the cell. We validate experimental results of the meniscus removal method by comparing them with reference data and outcomes of the Nicolson-Ross-Weir method.

Chronic cutaneous graft-versus-host disease manifesting as calcinosis cutis universalis on a background of widespread sclerodermatoid changes.

BACKGROUND: The cutaneous manifestations of graft-versus-host disease (GVHD) can be classified into acute and chronic forms. Acute GVHD is defined as a skin eruption that manifests within 100 days of transplantation, whereas chronic GVHD refers to cutaneous changes that appear 100 days or more posttransplantation. OBJECTIVE: Although most chronic forms fall within lichenoid and sclerodermoid forms, there is a multitude of less common presentations. These include xerosis, follicular prominence, ichthyosis, and pityriasis rosea-like, eczematous, or psoriasiform lesions. CONCLUSIONS: We report a previously unreported manifestation of chronic cutaneous GVHD, specifically calcinosis cutis universalis on a background of sclerodermoid changes.

Photodynamic therapy for actinic keratoses.

Actinic keratoses (AKs) are one of the most common conditions that are treated by dermatologists and they have the potential to progress to squamous cell carcinoma if left untreated. Photodynamic therapy (PDT) has emerged as a novel and versatile method of treating those lesions. Topical preparations of aminolevulinic acid and methyl aminolevulinate are commercially available photosensitizers, and numerous light sources may be used for photoactivation. This article focuses on practical aspects of PDT in the treatment of AKs, outcomes of relevant clinical trials, and special applications of PDT in transplant recipients and other who are predisposed to AK formation. Step-by-step descriptions of PDT sessions are presented.

Squamous cell carcinoma in recessive dystrophic epidermolysis bullosa, presenting as an ulcer that appears to be filled with granulation tissue.

BACKGROUND: Cutaneous squamous cell carcinoma (SCCA) is an important cause of death in patients with the severe form of recessive dystrophic epidermolysis bullosa (RDEB). These cancers often present with features that are different from those of actinically induced SCCA. OBJECTIVE: To emphasize the unusual features with which SCCA can present in RDEB and discuss early recognition of such cancers. METHODS: We present the case of a patient with RDEB who developed a cutaneous ulcer that appeared to be filled with heaped-up granulation tissue. Biopsy, however, showed moderately differentiated squamous cell carcinoma. RESULTS: The patient underwent wide surgical excision of the cancer, with split-thickness skin graft. She has remained disease-free three years later. CONCLUSION: In patients with RDEB, any ulcer that appears to be filled with heaped-up granulation tissue should be biopsied to rule out SCCA.