Electrochemically activated Co-Prussian blue analogue derived amorphous CoB nanostructures: Efficient electrocatalyst for oxygen evolution reaction

The oxygen evolution reaction is a kinetically sluggish half-cell reaction plays an important role in tuning the efficiency of various electrochemical energy conversion systems. However, this process can be facilitated...

A Histopathologic Approach to Uterine Niche: What to Expect and to Report in Hysteroscopy-Resected Isthmocele Specimens

As one of the emerging complications of caesarean sections (CSs), pathologists will have an important role in handling samples of uterine niches. An isthmocele is a defect at the site of a previous CS scar resulting in a variety of symptoms and niche-related subfertility. There is a deficiency in the literature of the histopathologic features of hysteroscopy-resected isthmocele ridges. Our aim is to fill this gap to highlight what to expect to see and what important findings to report to guide gynecologists to the results of hysteroscopic isthmoplasty in relation to symptoms improvement, fertility restoration, and potential complications. We found 22 cases of hysteroscopy-resected isthmoceles by performing a retrospective review study. The majority of the women were symptomatic with secondary infertility. The resected isthmocele edges were lined by endocervical, endometrial, and isthmic mucosa either combined or isolated depending on each case. Isthmoceles could be classified depending on the predominant lining mucosa into endocervical-isthmoendocervical (low) and endometrial-isthmic (high-intermediate) niches. This could be correlated with certain symptoms. The edges showed variably thickened fibrous and fibromuscular stromal tissue with characteristic thick-walled blood vessels. Some cases showed miscellaneous findings such as hemosiderin pigments with foreign body giant cell reaction and placental implantation site tissue reflecting a previous history of surgical repair and scar pregnancy. Cauterization artifacts may impose interpretation challenges for pathologists. Utility of certain special stains helps delineate the nature of badly cauterized tissues. It is important to report certain histologic findings in isthmocele samples to correlate with clinical findings and guide gynecologists.

Voltage Loss Analysis of Zinc-Cerium Redox Flow Batteries

Redox flow batteries (RFBs) are a relatively new generation of electrochemical devices suitable for large-scale energy storage applications. The separation between the electrolyte storage tanks and the electrochemical cell in RFBs simplifies the battery scale-up and facilitates the energy/power ratio tuning. Among the different types of RFBs investigated, those based on zinc and cerium are very attractive due to the large negative and positive electrode potentials in an aqueous media. Thus, zinc-cerium RFBs are capable of providing one of the highest cell voltages (~ 2.4 V) among flow [1]. To date, Zn-Ce RFBs have primarily been investigated galvanostatically to determine their charge, voltage and energy efficiencies and attempts have been made to suppress the rate of the hydrogen evolution side reaction [2,3]. In order to further optimize the performance of these batteries and to elucidate the future pathways to enhance their efficiency, the sources of voltage loss in the battery during discharge must be identified and the role of the positive and negative half-cells in the voltage loss determined. Toward this goal, we have conducted in situ polarization and EIS experiments on a full-cell Zn-Ce RFB with reference electrodes inserted in the system. At low and intermediate current densities, the main contributor to the voltage loss during discharge is the kinetic overpotential of the negative Zn/Zn2+ half-cell. On the other hand, at high current densities, mass transfer limitations at the positive Ce3+/Ce4+ half-cell cause a large potential drop in the system. From in situ kinetic studies, we have measured an exchange current density of ~ 7.4*10−3 A cm−2 for Zn oxidation and ~ 24.2*10−3 A cm−2 for Ce4+ reduction, which supports the findings from battery operation that the kinetics of the negative electrode reaction is slow compared to that of the positive electrode at low-to-intermediate current densities. The use of an alternative mixed methanesulfonate-chloride negative electrolyte to reduce the kinetic overpotential of the negative half-cell reaction and the influence of the flow rate on the mass-transfer rate of the positive half-cell reaction have also been investigated and will be discussed in this presentation.

AN UNUSUAL PRESENTATION OF PILONIDAL SINUS – A DIAGNOSTIC CHALLENGE!

Introduction: Pilonidal sinus (PNS) is any subcutaneous sinus containing hair. 97.8% of PNS are in sacrococcygeal region making it the most common site of PNS. Extrasacrococcygeal PNS accounts for approximately 2.2% of PNS. Few cases of PNS of atypical sites have been reported. The purpose of this paper is to report an unusual case of pilonidal sinus over the submandibular region. Case report: A 36 year old male patient presented with a painless swelling over left side of neck since 2 weeks which on examination had no tenderness and no local raise of temperature. Ultrasonography of neck was suggestive of abscess. Excision of the swelling was done and histopathological examination showed chronic inflammation with foreign body gaint cell reaction suggesting diagnosis of Pilonidal sinus. Conclusion: Pilonidal sinus over submandibular region is unusual and a diagnostic challenge. Total excision and primary closure was done in this case.