3,637 research outputs found
A preliminary review of organic materials single crystal growth by the Czochralski technique
The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed
Satellite applications to marine geodesy
Potential use of satellites for enhancing positioning capabilities and for marine geodetic contro
Apparent Change in Ion Selectivity Caused by Changes in Intracellular K+ during Whole-Cell Recording
AbstractIn whole-cell recordings from HEK293 cells stably transfected with the delayed rectifier K+ channel Kv2.1, long depolarizations produce current-dependent changes in [K+]i that mimic inactivation and changes in ion selectivity. With 10mM Ko+ or Ki+, and 140â160mM Nai,o+, long depolarizations shifted the reversal potential (VR) toward ENa. However, similar shifts in VR were observed when Nai,o+ was replaced with N-methyl-d-glucamine (NMG+)i, o. In that condition, [K+]o did not change significantly, but the results could be quantitatively explained by changes in [K+]i. For example, a mean outward K+ current of 1 nA for 2s could decrease [K+]i from 10mM to 3mM in a 10pF cell. Dialysis by the recording pipette reduced but did not fully prevent changes in [K+]i. With 10mM Ki,o+, 150mM Nai+, and 140mM NMGo+, steps to +20mV produced a positive shift in VR, as expected from depletion of Ki+, but opposite to the shift expected from a decreased K+/Na+ selectivity. Long steps to VR caused inactivation, but no change in VR. We conclude that current-dependent changes in [K+]i need to be carefully evaluated when studying large K+ currents in small cells
Concerns of Custom Harvesters
This study elicited the perceptions and concerns of custom harvesters regarding safety and health issues faced in their operations, selfâperceived knowledge of selected regulations, and selfâperceived ability to train employees on the safe operation of equipment. The average age of custom harvesters\u27 (CH) employees was 22 to 25 years (47.2%). The most common length of the harvest season was 5 to 6 months (70.9%). The most common responses to length of work day were 9 to 11 hours (34.5%) and 12 to 14 hours (54.5%). In general, CH ranked combine operation experience as most important when hiring employees. The CH felt inexperience was the leading contributor to lostâtime incidents. They were most concerned about DOT regulations and Worker\u27s Compensation rules, but also felt they had a good knowledge of those areas
Distinguishing Variability Regimes of Hawaiian Summer Rainfall: Quasi-Biennial and Interdecadal Oscillations
Summer precipitation in Hawai\u27i accounts for 40% of the annual total and provides important water sources. However, our knowledge about its variability remains limited. Here we show that statewide Hawai\u27i summer rainfall (HSR) variability exhibits two distinct regimes: quasi-biennial (QB, ~2 years) and interdecadal (~30â40 years). The QB variation is linked to alternating occurrences of the Western North Pacific (WNP) cyclone and anticyclone in successive years, which is modulated by the intrinsic El NiñoâSouthern Oscillation biennial variability and involves a positive feedback between atmospheric Rossby waves and underlying sea surface temperature (SST) anomalies. The interdecadal variation of HSR is largely modulated by the Pacific Decadal Oscillation through affecting upstream low-level humidity that affects topographic rainfall. HSR shows weak long-term drying trend during 1920â2019. This first description of the major physical drivers of summer rainfall variability provides key information for seasonal rainfall prediction in Hawai\u27i
Investigating the veracity of self-reported post-traumatic growth: a profile analysis approach
Research into posttraumatic growthâpositive psychological change that people report in their relationships, priorities in life, and self-perception after experiences of adversityâhas been severely critiqued. We investigated the degree to which community membersâ friends and relatives corroborated targetsâ self-perceived positive and negative changes as measured by the Posttraumatic Growth Inventory-42. We found corroboration only for negative changes when we examined overall (averaged) scores. However, using a profile analysis procedure, we found significant participantâinformant agreement on the domains of change that had relatively higher scores in the targetâs profile and those that had relatively lower scores. Our results demonstrate that informants were able to observe that targets had changed and were sensitive to the idiosyncratic ways in which these changes had manifested in targetsâ behavior
The Pacific Drought Knowledge Exchange: A Co-Production Approach to Deliver Climate Resources to User Groups
Drought is a growing threat to hydrological, ecological, agricultural, and socio-cultural systems of the tropics, especially tropical islands of the Pacific where severe droughts can compromise food and water security. Overcoming barriers to knowledge sharing between land managers and researchers is a critical cross-sector strategy for engaging and mitigating or adapting to drought. Here we describe the establishment and functioning of the Pacific Drought Knowledge Exchange (PDKE), which provides users with easier access to: (1) sector- and geography-specific climate information; (2) better and more comprehensive information; (3) improved technical assistance; and (4) a more collaborative information-transfer environment through participation in knowledge co-production. We focus on our collaborative work with managers of important tropical dryland ecosystems from three distinct geographies to pilot the collaborative development of climate change, climate variability, and drought âportfoliosâ featuring site-specific historical and forecasted future information. This information was then used to collaboratively produce factsheets that partners used to: (i) better understand past and projected climate for specific management units; (ii) integrate new climate knowledge into management planning; and (iii) support climate-focused educational and outreach efforts. This pilot effort demonstrates the successful application of climate-focused co-production in dry tropical landscapes
Comparative evaluation of [(99m)tc]tilmanocept for sentinel lymph node mapping in breast cancer patients: results of two phase 3 trials.
BackgroundSentinel lymph node (SLN) surgery is used worldwide for staging breast cancer patients and helps limit axillary lymph node dissection. [(99m)Tc]Tilmanocept is a novel receptor-targeted radiopharmaceutical evaluated in 2 open-label, nonrandomized, within-patient, phase 3 trials designed to assess the lymphatic mapping performance.MethodsA total of 13 centers contributed 148 patients with breast cancer. Each patient received [(99m)Tc]tilmanocept and vital blue dye (VBD). Lymph nodes identified intraoperatively as radioactive and/or blue stained were excised and histologically examined. The primary endpoint, concordance (lower boundary set point at 90 %), was the proportion of nodes detected by VBD and [(99m)Tc]tilmanocept.ResultsA total of 13 centers contributed 148 patients who were injected with both agents. Intraoperatively, 207 of 209 nodes detected by VBD were also detected by [(99m)Tc]tilmanocept for a concordance rate of 99.04 % (p < 0.0001). [(99m)Tc]tilmanocept detected a total of 320 nodes, of which 207 (64.7 %) were detected by VBD. [(99m)Tc]Tilmanocept detected at least 1 SLN in more patients (146) than did VBD (131, p < 0.0001). In 129 of 131 patients with â„1 blue node, all blue nodes were radioactive. Of 33 pathology-positive nodes (18.2 % patient pathology rate), [(99m)Tc]tilmanocept detected 31 of 33, whereas VBD detected only 25 of 33 (p = 0.0312). No pathology-positive SLNs were detected exclusively by VBD. No serious adverse events were attributed to [(99m)Tc]tilmanocept.Conclusion[(99m)Tc]Tilmanocept demonstrated success in detecting a SLN while meeting the primary endpoint. Interestingly, [(99m)Tc]tilmanocept was additionally noted to identify more SLNs in more patients. This localization represented a higher number of metastatic breast cancer lymph nodes than that of VBD
A Simple Inexpensive Bridgman-Stockbarger Crystal Growth System for Organic Materials
Direct observation of solid-liquid interface is important for the directional solidification to determine the desired interface shape by controlling the growth parameters. To grow good quality single crystals of novel organic nonlinear optical materials, a simple inexpensive Bridgman-Stockbarger (BS) crystal growth system has been designed and fabricated. Two immiscible liquids have been utilized to create two zones for this crystal growth system. Bulk single crystals of benzil derivative and n-salicylidene-aniline have been successfully grown in this system. The optimum lowering rate has been found to be 0.1 mm/h for the flat interface. Results on the crystal growth and other parameters of the grown crystals are presented
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