The growth of methylammonium lead iodide perovskites by close space vapor transport

Vapor deposition processes have shown promise for high-quality perovskite solar cells with potential pathways for scale-up to large area manufacturing. Here, we present a sequential close space vapor transport process to deposit CH₃NH₃PbI₃ (MAPI) perovskite thin films by depositing a layer of PbI₂ then reacting it with CH₃NH₃I (MAI) vapor. We find that, at T = 100 °C and pressure = 9 torr, a ∼225 nm-thick PbI₂ film requires ≥125 minutes in MAI vapor to form a fully-reacted MAPI film. Raising the temperature to 160 °C increases the rate of reaction, such that MAPI forms within 15 minutes, but with reduced surface coverage. The reaction kinetics can be approximated as roughly first-order with respect to PbI₂, though there is evidence for a more complicated functional relation. Perovskite films reacted at 100 °C for 150 minutes were fabricated into solar cells with an SLG/ITO/CdS/MAPI/Spiro-OMeTAD/Au structure, and a device efficiency of 12.1% was achieved. These results validate the close space vapor transport process and serve as an advance toward scaled-up, vapor-phase perovskite manufacturing through continuous vapor transport deposition.

This is the first demonstration of an all-vapor close space vapor transport process to deposit methylammonium lead iodide perovskites.     

Insecticide resistance in potential vector mosquitoes for West Nile virus in Japan

Culex pipiens complex is the significant vector mosquito of West Nile virus. To take stock of the current situation of insecticide susceptibilities and design an ideal mosquito control strategy, we collected Culex pipiens pallens Coquillet, Culex pipiens form molestus Forskal, and Culex quinquefasciatus Say from fields in Japan and conducted bioassays for five larvicides (fenitrothion, temephos, etofenprox, diflubenzuron, and pyriproxyfen) by using a larval dipping method. Among five insecticides tested, obvious reduced susceptibilities were observed for etofenprox, which is the only pyrethroid compound registered as a larvicide in Japan. Twenty-two of 56 colonies exhibited a >10% survival rate at the etofenprox concentration of 5.7 microg/ml, which is a 10 times higher concentration of the working solution. The LC50 of a colony collected from Fukuoka prefecture for etofenprox exceeded 60 microg/ml (resistance ratio >2,307), and this colony also exhibited cross-resistance to other pyrethroids, permethrin (299-fold) and phenothrin (1,200-fold). The insect growth regulators diflubenzuron and pyriproxyfen were found to be sufficiently effective enough to control Culex larvae present, but decreased sensitivities to these insecticides were slightly detected in some colonies of Cx. p. form molestus collected from urban areas. Several etofenprox-resistant colonies of Cx. p. form molestus exhibited simultaneously decreased susceptibilities to other insecticides, including temephos, diflubenzuron, and pyriproxyfen.     

Hyperechoic malignancies of the breast: Underlying pathologic features correlating with this unusual appearance on ultrasound

Hyperechogenicity in the breast on ultrasound (US) is usually regarded as a benign feature with only rare hyperechoic malignancies reported to date. In this study, we evaluated the pathologic findings on core needle biopsy of hyperechoic lesions and investigated the histologic features in malignancies that give rise to an echogenic pattern. A total of 163 core needle biopsies (CNB) were performed for “hyperechoic” or “echogenic” lesions between 1/1/05 and 7/31/17. Lesions were classified based on the proportion of hyperechoic areas identified. We found that all lesions with a homogenous hyperechoic pattern (>90% hyperechoic) were benign (n = 17), regardless of the type of margins. Malignancies were found in 21% (7/34, six invasive carcinomas and one lymphoma) of heterogenous lesions with ≥50% hyperechoic areas (all with noncircumscribed margins) and in 31% of lesions with <50% hyperechoic areas (19/61, 14 invasive carcinomas, two lymphomas, and three metastases), including five with circumscribed margins (one invasive carcinoma, one lymphoma, and three metastases). Two major US patterns were identified in malignant lesions, those with a hypoechoic center and hyperechoic rim, corresponding to a central tumor area with dense stroma and tumor cells infiltrating adipose tissue at the periphery (“rim pattern”), and a second “dispersed pattern” with hyperechoic areas distributed throughout the lesion. Hyperechoic malignancies were found to be comprised of a complex intermixture of elements of differing echogenicity including tumor cells, adipose tissue, and fluid (in tubules, stromal clefts, or blood vessels). Our findings support the importance of radiologists specifying the echogenic pattern of hyperechoic lesions, as heterogenous lesions are associated with a higher risk of malignancy and pathologists should be alert to the associated pathologic findings.     

A case of invasive hemolymphangioma of the pancreas

Hemolymphangioma of the pancreas is a very rare benign tumor. There were only five reports of this disease until March 2008. Herein, we report a case of hemolymphangioma of the pancreas with gastrointestinal bleeding due to duodenal invasion. A 53-year-old man had been admitted a referral hospital because of severe anemia due to gastrointestinal bleeding in December 2005. He was then transferred to our institute with a diagnosis of a tumor of the head of the pancreas with duodenal invasion in January 2006. No abnormalities were revealed except for anemia in laboratory data including CEA and CA19-9. Gastrointestinal endoscopy revealed bleeding at the duodenum. Computed tomography also demonstrated a heterogenous mass at the pancreatic head and suspected invasion to the duodenal wall. Ultrasonography showed a huge mass at the pancreatic head with a mixture of high and low echoic areas. Pylorous-preserving pancreatoduodenectomy was performed. The pancreatic tumor was soft and had invaded to the duodenum. The pathological diagnosis was a hemolymphangioma of the pancreas invaded to the duodenum. His postoperative course was uneventful and he was discharged on the 26th d after surgery. Hemolymphangioma of the pancreas is a very rare benign tumor. In a literature review until March 2008, we found five case reports. Major symptoms are abdominal pain and distension due to the enlarged tumor. However, we experienced a case of hemolymphangioma of the pancreas with gastrointestinal bleeding due to invasion to the duodenum. This disease is a very rare entity, but should be considered when patients have gastrointestinal bleeding.     

Radiation dosimetry in specific area radiography

An improved head-and-neck phantom was constructed from a human skull, cervical vertebrae, and Mix D, a mixture of wax, plastic, and metal oxides with x-ray absorbing and scattering properties similar to water and soft tissues. Lithium fluoride thermoluminescent dosimeters were calibrated and then exposed within the phantom. The doses at 17 anatomic sites were calculated for each of the 18 specific area radiographs in a complete intraoral radiographic survey.