The Torsional Quartz-Crystal Viscometer

A complete theoretical analysis of the fluid and solid dynamics of the torsional quartz crystal viscometer is presented which for the first time, establishes a firm theoretical basis for two working equations whereby the viscosity of a fluid may be determined from measurements of the resonant frequency of the crystal and the width of the resonance when immersed in the fluid. Modern instrumentation means that it is possible to achieve higher resolution in the measurement of these two quantities than hitherto and the new theory opens the way to securing a concomitant accuracy in the determination of viscosity.

Progress and pitfalls in dating deformation with carbonate geochronology

<p>Several isotopic systems can potentially be used to provide absolute chronology of carbonate minerals; these include Rb-Sr, Sm-Nd, U-Pb and U-Th. The production of a robust date requires incorporation of the parent isotope during formation, and ideally low abundance of the daughter isotope. Variable parent-daughter (P/D) abundance during formation additionally can increase the robustness of the resulting isochron. The ability to use high spatial resolution sampling via laser ablation (LA-) ICP-MS, makes it the most attractive technique, as varying P/D ratios can be sampled within single age domains, whether these be crystals, growth bands, or other textural domains. Of the systems available in carbonate, U-Pb is the only one that is commonly applied with LA-ICP-MS methods, although the others are all possible with modern instrumentation. Of note, collision-cell technology means that Rb-Sr is regaining popularity as an in situ dating method. Carbonate geochronology can be achieved at a range of timescales, with U-Th ranging from 100s yrs to ca. 500 ka, and U-Pb ranging from 100s ka to 100s Ma. The potential for isotopic disequilibrium effecting measured U-Pb ages, means that young (< 10 Ma) U-Pb dates are susceptible to inaccuracy. Published LA-ICP-MS U-Pb dates suggest that this method can be pushed well into the Precambrian.</p><p> </p><p>The application of U-Th and U-Pb geochronology to provide direct timing constraints on deformation gained ground around 10 and 5 years ago, respectively. Because LA-ICP-MS instrumentation is relatively common, and because ancient carbonates provide undated material of significant interest, U-Pb in particular has become a rapidly growing technique. The biggest advance in LA-ICP-MS U-Pb dating has been the characterisation of matrix-matched calcite reference materials (RMs). The observation of minor matrix-related effects between carbonate matrices however, means that the availability of well characterised RMs for minerals such as dolomite and siderite, are a limiting factor in the accuracy of these non-calcite dates. In terms of deformation, most existing data corresponds to calcite.</p><p> </p><p>Calcite precipitates from fluid at a range of temperatures in the upper crust, with fluid-flow typically being enhanced by brittle deformation, i.e. faulting and fracturing. To link calcite dates to the timing of specific deformational events, such as fault slip or fracture-opening, various ‘syn-tectonic’ or ‘syn-kinematic’ vein types have ben utilised. These include slickenfibres, breccia cements, and various types of vein arrays. Each of these structures has variable ability to faithfully record the timing of fault slip, and the ability to link calcite mineralisation to the timing of fault slip remains one of the most assumptive parts of this method. Detailed petrographic and compositional characterisation and documentation are required, for which a range of methods are available, such as cathodoluminescence and trace element mapping. Along with a summary of the advances in carbonate geochronology, various examples of vein structures and of methods for characterisation will be discussed, including examples where there is evidence for overprinting by later fluid-flow.</p>

Gunshot Injuries of the Maxillofacial Region

The current principles and pillars in the management of gunshot maxillofacial injuries have largely been the result of an exhaustive experimental approach spanning centuries of warfare. However, while medical professionals endlessly strive to revolutionize healthcare in combat injury, there are simultaneous efforts directed towards creation of new and ever more lethal arms and ammunition. Consequently, these doctrines continue to undergo significant transformations with a contemporary understanding of war injuries as well as the advent of new surgical materials and modern instrumentation. Previously accepted principles like external pin fixations without adequate exposure of bony fragments, fracture stabilization using intra-osseous wiring and inter-maxillary fixation, minimal attention to primary soft tissue closure and delay in definitive management have been sidelined for most of the part. On the other hand, new principles have evolved that including adequate exposure of fracture fragments and precise anatomic rigid fixation, immediate bone grafting, definitive soft tissue management and early definitive repair allowing for better return of patients to their pre-traumatic appearance.

Quantitative analysis of biochemical processes in living cells at a single-molecule level: a case of olaparib-PARP1 (DNA repair protein) interactions

Quantitative description of biochemical processes inside living cells and at single-molecule levels remains a challenge at the forefront of modern instrumentation and spectroscopy. This paper demonstrates such single-cell, single-molecule analyses...

Hierarchical interlocked orthogonal faulting in the 2019 Ridgecrest earthquake sequence

A nearly 20-year hiatus in major seismic activity in southern California ended on 4 July 2019 with a sequence of intersecting earthquakes near the city of Ridgecrest, California. This sequence included a foreshock with a moment magnitude (Mw) of 6.4 followed by a Mw 7.1 mainshock nearly 34 hours later. Geodetic, seismic, and seismicity data provided an integrative view of this sequence, which ruptured an unmapped multiscale network of interlaced orthogonal faults. This complex fault geometry persists over the entire seismogenic depth range. The rupture of the mainshock terminated only a few kilometers from the major regional Garlock fault, triggering shallow creep and a substantial earthquake swarm. The repeated occurrence of multifault ruptures, as revealed by modern instrumentation and analysis techniques, poses a formidable challenge in quantifying regional seismic hazards.

Wintertime Orographic Cloud Seeding—A Review

This paper reviews research conducted over the last six decades to understand and quantify the efficacy of wintertime orographic cloud seeding to increase winter snowpack and water supplies within a mountain basin. The fundamental hypothesis underlying cloud seeding as a method to enhance precipitation from wintertime orographic cloud systems is that a cloud’s natural precipitation efficiency can be enhanced by converting supercooled water to ice upstream and over a mountain range in such a manner that newly created ice particles can grow and fall to the ground as additional snow on a specified target area. The review summarizes the results of physical, statistical, and modeling studies aimed at evaluating this underlying hypothesis, with a focus on results from more recent experiments that take advantage of modern instrumentation and advanced computation capabilities. Recent advances in assessment and operations are also reviewed, and recommendations for future experiments, based on the successes and failures of experiments of the past, are given.

Monitoring of Technogenic Destructions of Oil and Gas Facili-ties using 3D Laser Scanning

This article discusses application of 3D laser scanning aimed at assessment of consequences of destructions resulted from fires and other technogenic disasters of oil and gas facilities. Deformations of structures and equipment as a consequence of emergencies sometimes cannot be detected visually. It is required to apply modern instrumentation to determine deviations from designed parameters. In addition, after disasters it is required to determine the scope of loss and faults of equipment. Application of 3D laser scanning makes it possible to estimate both availability of buildings and equipment for further operation and the scope of destructions at complex engineering facilities of oil and gas industry. Laser scanning makes it possible to reduce significantly time required for examination and data processing in comparison with other measurement methods.

Teaching Analytical Instrumental Analysis to Undergraduates in Specialized Degree Programs with Heterogeneous Prior Knowledge: Reflections on Inquiry Based Lecture Activities

An adjunct faculty member and graduate instructional assistant (GIA) introduced inquiry-based activities into a 20-student undergraduate analytical instrumental analysis (AIA) lecture course, and reflect on their teaching assumptions, practices and experiences. The increased need for interdisciplinary scientific programs now has an AIA course serving multiple Bachelor of Science degrees in environmental sciences, forensic sciences, molecular biology, and secondary science education. However, we learned degree specialization also introduces into a course, student populations possessing heterogeneous prior knowledge, making an instructor’s rendering of student prerequisite skills a greater challenge. Guided by a pretest assessment, instructional activities were modified or developed by the authors and aimed at enhancing student engagement and motivation to mitigate prior knowledge gaps, improve analytical problem-solving skills, and facilitate a deeper understanding of modern instrumentation design and function. Detailed activity rationale and descriptions are presented. Activities included using readily available Internet bioinformatics and database tools for analytical problem-solving; demonstrating principles of electronic hardware and software design and integration; and creating interdisciplinary scientific narratives using biological, environmental, and industrial molecular exemplars. Our teaching reflections reference weekly post-lecture instructor/GIA discussions, strategic student questioning, collaborative classroom activity observations, and formative assessments. We propose continual instructional reflection is essential for a course serving multiple specialized degrees programs in a scientific field and facilitates preparation for students entering the workforce or graduate school. Further, our observations suggest inquiry-based, real-world activities relevant to modern instrumentation and its applications, assisted students in resolving heterogeneous prior knowledge gaps.