Athermalized carrier multiplication mechanism for detectors using an amorphous silicon gain medium.

In this paper, we investigate the temperature sensitivity of gain and breakdown voltage of detectors based on cycling excitation process (CEP), an internal signal amplification mechanism found in amorphous silicon (a-Si). Changes in gain and breakdown voltage with temperature can result in pixel-to-pixel signal variation in a focal plane array and variations in photon detection efficiency for single photon detectors. We have demonstrated athermalized CEP detectors with their gain and breakdown voltage being nearly temperature independent from 200 K to 350 K, covering the temperature range for practical applications. The device appears to be more thermally stable than avalanche photodetectors (APDs) with different gain media such as Si, InP, InAlAs, etc. The excellent thermal stability of CEP detectors is attributed to the field-enhanced tunneling process for excitation of localized carriers into the mobile bands, which dominates over the phonon excitation process.

Operando time-resolved X-ray absorption spectroscopy reveals the chemical nature enabling highly selective CO2 reduction.

Copper electrocatalysts have been shown to selectively reduce carbon dioxide to hydrocarbons. Nevertheless, the absence of a systematic study based on time-resolved spectroscopy renders the functional agent-either metallic or oxidative Copper-for the selectivity still undecidable. Herein, we develop an operando seconds-resolved X-ray absorption spectroscopy to uncover the chemical state evolution of working catalysts. An oxide-derived Copper electrocatalyst is employed as a model catalyst to offer scientific insights into the roles metal states serve in carbon dioxide reduction reaction (CO2RR). Using a potential switching approach, the model catalyst can achieve a steady chemical state of half-Cu(0)-and-half-Cu(I) and selectively produce asymmetric C2 products - C2H5OH. Furthermore, a theoretical analysis reveals that a surface composed of Cu-Cu(I) ensembles can have dual carbon monoxide molecules coupled asymmetrically, which potentially enhances the catalyst's CO2RR product selectivity toward C2 products. Our results offer understandings of the fundamental chemical states and insights to the establishment of selective CO2RR.

Edgeless Ag-Pt Bimetallic Nanocages: In Situ Monitor Plasmon-Induced Suppression of Hydrogen Peroxide Formation.

Improvements in the performance of electrocatalysts, along with continuing advances in selective pathway for target reaction, have great potential to offer opportunities in designing competitive reactions especially for using a photophysical process owing to its tunable properties. Herein, we demonstrated a first empirical evidence of suppressing the formation of undesired peroxide intermediate through plasmonic effects, in which plasmonic Ag-Pt bimetallic nanocages were synthesized with an edgeless feature, and a custom-made RDE/RRDE working station was designed to provide unique means by which to in situ realize the plasmon-induced effects toward the target reaction. The edgeless Ag-Pt bimetallic nanocages with hollow interior performed newly plasmon-induced effects, which was characteristic of photodependent nature to suppress the formation of undesired peroxide intermediate. We concluded that the plasmon-induced hot electron transfer governed the suppression of peroxide formation instead of plasmon-induced heating that would cause a negative effect (i.e., increase of peroxide yield), in which the hot electron transfer of Ag nanostructure offered a sufficient energy to populate the antibonding orbital of O2 as illustrated by in situ X-ray absorption approach. This rapid light-dependent nature corresponding to localized surface plasmon resonance in present nanocages can potentially offer synergetic strategies toward altering the chemical reactions or reaction pathways in various fields.

Meconium exposure dependent cell death and apoptosis in human alveolar epithelial cells.

Alveolar epithelial cells of neonates are directly exposed to aspirated meconium during meconium aspiration syndrome (MAS). This study was designed to investigate the influence of quantity and time of meconium exposure on the cell viability and caspase activity in type II human alveolar epithelial cells. Human alveolar epithelial cells were incubated with human meconium suspension at different concentrations and for different times. Cell viability and DNA fragmentation were investigated together with caspases activity and the amount of Bcl-2 protein present. We found that cell viability was significantly lower in cells exposed to a higher concentration of meconium. This was also true for cells exposed to meconium for longer. Significantly higher DNA fragmentation, an approximately two- to fivefold increase, was observed in cells that had been exposed to higher (5% and 10%) concentration of meconium compared to those treated with lower (0.1% and 1%) concentrations (P < 0.05). The activity of most apoptotic initiators (caspase 2, 8, 9, 10) and effectors (caspase 3, 6) were found to be significantly higher in cells subject to greater meconium exposure compared to cells with no or minor meconium exposure. The level of Bcl-2 was also found to be significantly decreased in meconium-exposed cells (P < 0.05). In conclusion, human meconium would seem to induce direct cell death as well as caspase-dependent apoptosis in alveolar epithelial cells; the amount and period of exposure to meconium are crucial factors in this process. Thus, removing aspirated meconium should alleviate lung cell damage in neonates and improve the outcome with MAS.

Primary malignant mixed müllerian tumor of the ovary.

OBJECTIVE: To present a case of malignant mixed müllerian tumor of the ovary, a rare and aggressive ovarian malignant tumor with poor prognosis. CASE REPORT: A 52-year-old woman consulted our outpatient department with complaints of abdominal distention and a firm palpable mass over her lower abdomen. Physical examination and computerized tomography revealed cystic mass lesions on the bilateral adnexal areas. Ovarian cancer was suspected, so the patient underwent exploratory laparotomy. Optimal debulking surgery was performed, and final pathology revealed malignant mixed müllerian tumor of the ovary. Chemotherapy using ifosfamide and cisplatin were administered postoperatively, and adjuvant was also administered. After six cycles of chemotherapy, the patient is well with no signs of recurrence. CONCLUSION: Ovarian malignant mixed müllerian tumor usually yields poor outcomes; hence, aggressive treatment with optimal debulking surgery followed by combination chemotherapy using ifosfamide and cisplatin may improve patient outcomes.

Conditions associated with hypertension in a high-risk premature infant.

Hypertension is an uncommon but significant problem in high-risk neonates and infants, and the spectrum of potential causes is broad. Here, we describe an extremely premature infant (birth weight, 728 g; gestational age, 27 weeks) with multiple complications and hypertension. During admission, umbilical artery catheters were used for a period of time, and he suffered from respiratory distress syndrome, intraventricular hemorrhage, pulmonary hemorrhage, patent ductus arteriosus, pericardial effusion, heart failure, repeated sepsis, anemia, thrombocytopenia, chronic lung disease, and progressive liver damage. He was treated with multiple medications, including erythropoietin, indomethacin, epinephrine, dopamine, aminophylline, multiple antibiotics, amphotericin B, and total parenteral nutrition. Hypertension was first noted when he was 41 days old, with spontaneous remission. It then recurred, reaching higher than 100 mmHg when he was almost 4 months old. After stopping erythropoietin, hypertension subsided for a short period of time and went up again. Multiple factor-related hypertension in this premature infant was considered. Related literature on hypertension in premature infants is reviewed. In conclusion, multiple factors can influence blood pressure and may induce hypertension in high-risk premature infants. Thus, blood pressure should be closely monitored in high-risk premature infants. Judicious use of all medications and interventions are crucial to decrease the incidence of hypertension in high-risk premature infants.