Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use

Preload Loss in a Spacecraft Fastener via Vibration-Induced Unwinding

Sound engineering practice requires that fasteners and bolted joints maintain preload in service. NASA recently concluded a series of vibration tests of a multicomponent structure intended to simulate an upper stage section of a launch vehicle. The stacked components were joined through six circumferentially placed bolted cup-cone-style pyrotechnic joint mechanisms designed to share spacecraft structural loads and then enable separation during ascent. Over the course of the vibration test campaign, all six bolted cup-cone mechanisms experienced some degree of preload loss with two mechanisms losing half of their original bolt preload. A subsequent forensic anomaly investigation concluded that vibration-induced unwinding of the preload nut-and-bolt assemblies occurred despite the use of safety wire and high levels of thread friction. A series of experiments were done to better understand how large, heavily preloaded fasteners could unwind. Additionally, thread friction torque was measured and the fastener locking capability of safety wire was evaluated. The friction coefficient between the clamped cup-cone components was characterized and finally a highly instrumented mechanism-level vibration test was done to reproduce the unwinding phenomenon to better understand the mechanism's behavior. The conclusion drawn was that vibration and structural forces led to relative motion (sliding) of the clamped components, resulting in self-loosening and unwinding effects on the nut-and-bolt assembly. To counter this phenomenon, more effective fastener locking methodologies were recommended and a follow-on effort was initiated to quantify the relationship between preload, component motion, and resulting unwinding forces. It is hoped that elucidation of these effects can be used to design more effective fastener locking features

What is the effect of a decision aid in potentially vulnerable parents? Insights from the head CT choice randomized trial.

ObjectiveTo test the hypotheses that use of the Head CT Choice decision aid would be similarly effective in all parent/patient dyads but parents with high (vs low) numeracy experience a greater increase in knowledge while those with low (vs high) health literacy experience a greater increase in trust.MethodsThis was a secondary analysis of a cluster randomized trial conducted at seven sites. One hundred seventy-two clinicians caring for 971 children at intermediate risk for clinically important traumatic brain injuries were randomized to shared decision making facilitated by the DA (n = 493) or to usual care (n = 478). We assessed for subgroup effects based on patient and parent characteristics, including socioeconomic status (health literacy, numeracy and income). We tested for interactions using regression models with indicators for arm assignment and study site.ResultsThe decision aid did not increase knowledge more in parents with high numeracy (P for interaction [Pint ] = 0.14) or physician trust more in parents with low health literacy (Pint  = 0.34). The decision aid decreased decisional conflict more in non-white parents (decisional conflict scale, -8.14, 95% CI: -12.33 to -3.95; Pint  = 0.05) and increased physician trust more in socioeconomically disadvantaged parents (trust in physician scale, OR: 8.59, 95% CI: 2.35-14.83; Pint  = 0.04).ConclusionsUse of the Head CT Choice decision aid resulted in less decisional conflict in non-white parents and greater physician trust in socioeconomically disadvantaged parents. Decision aids may be particularly effective in potentially vulnerable parents

Cold Collision Frequency Shift of the 1S-2S Transition in Hydrogen

We have observed the cold collision frequency shift of the 1S-2S transition in trapped spin-polarized atomic hydrogen. We find $\Delta \nu_{1S-2S} = -3.8(8)\times 10^{-10} n Hz cm^3$, where $n$ is the sample density. From this we derive the 1S-2S s-wave triplet scattering length, $a_{1S-2S}=-1.4(3)$ nm, which is in fair agreement with a recent calculation. The shift provides a valuable probe of the distribution of densities in a trapped sample.Comment: Accepted for publication in PRL, 9 pages, 4 PostScript figures, ReVTeX. Updated connection of our measurement to theoretical wor

POTENCIAL AGRONÔMICO DE Eugenia candolleana D.C. EM ÁREA DE RESTINGA LITORÂNEA EM ARAQUARI-SC, BRASIL: RESULTADOS PARCIAIS

Eugenia candolleana D.C. (Myrtaceae) é uma espécie florestal frutífera endêmica da Mata Atlântica. Apesar da planta possuir propriedades medicinais e de seus frutos serem apreciados para o consumo in natura e na culinária, carece de informações técnicas no âmbito agronômico, principalmente para as condições do litoral nordeste de Santa Catarina. Este trabalho teve por objetivos verificar aspectos relativos ao potencial agronômico de E. candolleana D.C. em área de restinga litorânea. em Araquari-SC, Brasil. O estudo foi realizado em uma população plantas existentes na área do IFC-Campus Araquari (26°22'12'' S e 48°43' 19'' O), durante o período 01/08/2019 a 31/07/2020. Foram analisados: o período de colheita; a estimativa de produção de frutos, determinada pelo acumulado de colheita de todos os frutos maduros por planta; o comportamento pós-colheita, por meio da determinação do “tempo de vida de prateleira” de frutos frescos maduros e recém colhidos, mantidos a 10°C e 25°C, sendo determinadas a matéria fresca (g) e o teor total de sólidos solúveis (°Brix) aos 0, 2, 4, 6 e 8 dias após a colheita, bem como verificadas a ocorrência de alterações visuais nos frutos. Também foi observada a ocorrência de danos causados por pássaros, insetos ou doenças, obtida pela análise visual dos frutos durante a colheita e respectivo cálculo do percentual de frutos danificados. Os frutos foram acondicionados em bandejas plásticas. Da população de plantas observadas, foi possível realizar a colheita em apenas uma, possivelmente devido à juvenilidade das demais. O período de colheita de frutos foi de 29 dias, de 28/02/2020 à 28/03/2020, sendo realizadas ao todo 11 colheitas. Foi possível verificar duas etapas de produção, a primeira de 11 dias, referente à primeira florada e a outra de 14 dias de maior intensidade e produção. A produção total estimada foi 22,17 kg.planta-1 e o pesomédio dos frutos foi de 5,09g. Houveram danos decorrentes de pássaros e/ou queda natural em 21% dos frutos. O tempo de prateleira foi maior para frutos mantidos refrigerados, com redução de 12,06 para 11,24 °Brix e de 3% para matéria fresca aos 8 dias após a colheita. Frutos mantidos à 25°C reduziram de 12,5 para 11,42, 7,42 e 7,24 °Brix aos 4, 6 e 8 dias após a colheita, respectivamente, com cerca de 14% de redução de matéria fresca no final do período. Aos quatro dias após a colheita à 25°C, os frutos apresentaram odor desagradável, possivelmente devido a presença de larvas de insetos (mosca das frutas), sendo esta a principal causa de danos observada em frutos no final do tempo de prateleira. De acordo com as condições em que o trabalho foi desenvolvido pode-se concluir que: E. candolleana apresenta potencial agronômico quanto à produtividade de frutos; o reduzido tempo de prateleira demanda cuidados na comercialização de frutos frescos in natura e a refrigeração é uma alternativa na conservação da qualidade dos frutos em pós-colheita; Mosca das frutas é a principal praga encontrada, com potencial de dano econômico principalmente em pós-colheita

Nitric oxide sensing in plants is mediated by proteolytic control of group VII ERF transcription factors

Nitric oxide (NO) is an important signaling compound in prokaryotes and eukaryotes. In plants, NO regulates critical developmental transitions and stress responses. Here, we identify a mechanism for NO sensing that coordinates responses throughout development based on targeted degradation of plant-specific transcriptional regulators, the group VII ethylene response factors (ERFs). We show that the N-end rule pathway of targeted proteolysis targets these proteins for destruction in the presence of NO, and we establish them as critical regulators of diverse NO-regulated processes, including seed germination, stomatal closure, and hypocotyl elongation. Furthermore, we define the molecular mechanism for NO control of germination and crosstalk with abscisic acid (ABA) signaling through ERF-regulated expression of ABSCISIC ACID INSENSITIVE5 (ABI5). Our work demonstrates how NO sensing is integrated across multiple physiological processes by direct modulation of transcription factor stability and identifies group VII ERFs as central hubs for the perception of gaseous signals in plants