Explore the vast range of titles available.

Nitrous oxide abuse can have detrimental effects on the central and peripheral nervous systems. This case study report aims to demonstrate a combination of severe generalized sensorimotor polyneuropathy and cervical myelopathy related to vitamin B12 deficiency following nitrous oxide abuse. We present a clinical case study and literature review examining primary research—published between 2012 and 2022—reporting nitrous oxide abuse affecting the spinal cord (myelopathy) and peripheral nerves (polyneuropathy); 35 articles were included in the review with a total of 96 patients, where the mean “patients” age was 23.9 years and were in a 2:1 male/female ratio. Of the 96 cases, within the review, 56% of patients were diagnosed with polyneuropathy, most commonly impacting the nerves of the lower limb (62%), while 70% of patients were diagnosed with myelopathy, most commonly impacting the cervical region (78%) on the spinal cord. In our clinical case study, a 28‐year‐old male underwent a multitude of diagnostic investigations for bilateral “foot drop” and sense of lower limb stiffness as ongoing complications of a vitamin B12 deficiency secondary to recreational nitrous oxide abuse. Both the literature review and our case report emphasize the dangers of recreational nitrous oxide inhalation, colloquially termed “nanging” and the risks it presents to both the central and peripheral nervous systems, which is erroneously considered by many recreational drug users to be less harmful than other illicit substances. Our case report emphasizes the danger of recreational nitrous oxide inhalation and the risks it presents to both the central and peripheral nervous systems, which is considered by many recreational users to be less harmful than other illicit substances.

The move toward green, sustainable, natural products has been growing in the cosmetic and personal care industry. Ingredients derived from marine organisms and algae are present in many cosmetic products. In this study, a new green ingredient, a wax (i.e., long-chain alkenones) derived from Isochyrsis sp., was evaluated as an alternative for cosmetic waxes. First, the melting point was determined (71.1–77.4 °C), then the alkenones’ thickening capability in five emollients was evaluated and compared to microcrystalline wax and ozokerite. Alkenones were compatible with three emollients and thickened the emollients similarly to the other waxes. Then, lipsticks and lip balms were formulated with and without alkenones. All products remained stable at room temperature for 10 weeks. Lipstick formulated with alkenones was the most resistant to high temperature. Finally, alkenones were compared to three cosmetic thickening waxes in creams. Viscosity, rheology, and stability of the creams were evaluated. All creams had a gel-like behavior. Both viscosity and storage modulus increased in the same order: cream with alkenones < cetyl alcohol < stearic acid < glyceryl monostearate. Overall, alkenones’ performance was comparable to the other three waxes. Alkenones can thus offer a potential green choice as a new cosmetic structuring agent.

This qualitative, multiple case study provided comprehensive descriptions of the conceptual difficulties and learning experiences of in-service teachers as they improved their ability to effectively model fraction division with pictorial diagrams. Video data were collected on eight teachers as they individually progressed through a professional development (PD) program. The data were used to generate case-based descriptions and to conduct a cross-case synthesis.Ma’s Knowledge Package for Understanding the Meaning of Division by Fractions and Vergnaud’s Multiplicative Conceptual Field provided the conceptual framework for the PD tasks. The Knowledge in Pieces (KiP) epistemological framework provided a lens for the analysis of the participants’ engagement in the tasks.Results from the analysis of interview data contributed to the literature by identifying participants’ underlying conceptual resources. Some of these conceptual resources were idiosyncratic, such as conceptualizing partitive division with fractions as a type of density. Other conceptual resources and their functions were common, such as knowing that the quotient is based on scaling the divisor to a value of one yet being unable to identify it in some contexts.Additionally, distinct psychological structures emerged that might be common among learners when engaging in partitive division with fractional divisors. The participants in this study exhibited multiple models of partitive division that generalized into two distinct structures of partitive division with fractional divisors. These models generalized into part-whole models and unit-rate models. Part-whole models attended to a single referent. The referent was seen as a quantity, part of which was known; or a process, part of which was completed. Unit-rate models attended to separate referents for the dividend and divisor. This finding extends the research literature as the structures and their variants seen in the present study do not appear to have received much attention.Results of this study can be leveraged in curriculum design for teacher education on the subject of division with fractions. Results suggest that the KiP epistemological framework is a productive analytical framework for future research on learners’ connections between partitive division and other mathematics topics to which it is foundational, such as rate, intensive quantity, proportion, derivatives, probability, and statistics.

Electrical neuron stimulation holds promise for treating chronic neurological disorders, including spinal cord injury, epilepsy, and Parkinson’s disease. The implementation of ultrathin, flexible electrodes that can offer noninvasive attachment to soft neural tissues is a breakthrough for timely, continuous, programable, and spatial stimulations. With strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability. We introduce herein a concept of longlived flexible neural electrodes using silicon carbide (SiC) nanomembranes as a faradic interface and thermal oxide thin films as an electrical barrier layer. The SiC nanomembranes were developed using a chemical vapor deposition (CVD) process at the wafer level, and thermal oxide was grown using a high-quality wet oxidation technique. The proposed material developments are highly scalable and compatible with MEMS technologies, facilitating the mass production of long-lived implanted bioelectrodes. Our experimental results showed excellent stability of the SiC/silicon dioxide (SiO₂) bioelectronic system that can potentially last for several decades with well-maintained electronic properties in biofluid environments. We demonstrated the capability of the proposed material system for peripheral nerve stimulation in an animal model, showing muscle contraction responses comparable to those of a standard non-implanted nerve stimulation device. The design concept, scalable fabrication approach, and multimodal functionalities of SiC/SiO₂ flexible electronics offer an exciting possibility for fundamental neuroscience studies, as well as for neural stimulation–based therapies.

Independent testing and verification of emerging technologies are vital parts of the technology-commercialization process. With the rapid development of carbon capture and utilization (CCU) technologies, where existing standards and certifications do not exist, independent verification approaches and guidelines can provide a means to obtain credible information for an emerging market. The ISO 14034:2016—Environmental Management: Environmental Technology Verification (ETV) standard can serve as a foundational platform to ensure the consistency, quality and credibility of data on CCU technology performance, enabling direct comparisons between technologies and reducing risk to decision-makers regarding potential investment, future deployment and ultimate impacts of CCU innovations. Applying the fundamental principles of ISO 14034 to the evaluation of nine finalist CCU technologies competing in the NRG COSIA Carbon XPRIZE ensured that data used to evaluate competitors was of high quality, consistent across technologies and met the information needs of the XPRIZE and competition judges responsible for selecting winners. The approaches outlined here, including verification parameters and verification tasks for both XPRIZE-specific technology evaluations and full CCU technology evaluation by an accredited entity in conformance with the ISO 14034 standard, provide insight into the potential benefits—methodological consistency, high-quality data, independent oversight, methodological flexibility and broad applicability—and limitations—technology readiness and applicability, verification and instrumentation costs and lack of specificity—of the approach in an application for the evaluation of emerging technologies. Further application of the ISO 14034 standard and principles, developed through a consensus approach that incorporates other developing guidelines, can drive consistency and credibility for technology-performance evaluations across the CCU sector, ultimately leading to reduced risk and improved market access for new innovations.

The NRG COSIA Carbon XPRIZE—a $20 million prize competition focused on the development and scaling of innovative carbon-capture and -utilization technologies—placed credible data at the forefront of its scoring and ranking approach for the selection of prize-winners. To guarantee the quality of the submitted data, independent third-party verifiers reviewed each candidate technology and data set. While the Carbon XPRIZE contenders demonstrated a variety of CO2-utilization technologies at various levels of technical maturity and scale, it was found that early evaluation of the impact of measurements on process performance parameters via sensitivity analysis should influence the selection of instruments that have appropriate accuracy. In addition to appropriate accuracy, this assessment can lead to reduced costs associated with instrumentation rather than simply buying the ‘best’ instrument while simultaneously ensuring that uncertainties are kept as low as possible. With proper pre-planning, good engineering practice and good measurement practice, it is possible to optimize uncertainty against the costs and usability of instrumentation and data systems.

Scoring the technologies in competition for the NRG Canada’s Oil Sands Innovation Alliance Carbon XPRIZE required an economic evaluation to estimate the value created through the conversion of CO2 emissions into products. Across all of the Teams participating in the competition, 58 different materials were consumed and produced. Standardized prices and market sizes needed to be established for each of these materials to ensure a consistent evaluation across all Teams. The Standards Data Set (SDS) was created as a standardized database of economic data used in the competition. The rationale for the SDS project and the methodology for researching each material is described. Ultimately, credible material definitions using the SDS methodology were created for all materials, and some research and methodological customization were required for materials that did not have credible, publicly available market data. The methodologies for establishing credible values and market sizes for concrete, concrete admixtures and syngas are highlighted as examples of materials whose value and markets are not easily defined.

Continuous intramuscular stimulation of tibialis anterior (TA) was used to test the hypothesis that irregular trains of stimuli can increase force production and offset the magnitude of fatigue when compared with a continuous train of regular stimuli at an identical mean frequency (19 or 24 Hz). To achieve this, tungsten microelectrodes were inserted into the muscle belly into the motor point of the tibialis anterior muscle of able‐bodied individuals (aged 19–50) and stimulated at current intensities ranging from 5 to 7 mA. The motor point was stimulated with a continuous train of regular stimulation at either 19 or 24 Hz (n = 11) or until the force declined below 25% of the peak force at the onset of stimulation. For the first seven subjects, no fatigue was exhibited, and thus, we simply compared the forces generated by the regular and irregular segments of the continuous train (120 sec for each segment). For four additional subjects, we delivered a higher frequency train (24 Hz) that elicited some fatigue. Once the force had declined below 25% of the initial peak force (which took between 140 and 210 sec), the continuous irregular train was integrated. Interestingly, for those subjects who exhibited muscular fatigue, force always began to rise again once the irregularity was incorporated into the continuous regular train of stimulation at the identical mean frequency (24 Hz). We conclude that incorporating irregularity into continuous trains of stimuli offers a significant advantage to the human neuromuscular system during both fatigued and nonfatigued states and could offer benefits to therapies such as functional electrical stimulation (FES). Intramuscular stimulation of tibialis anterior revealed that irregular trains of stimulation generate greater force responses that regular trains of the same mean frequency.

Human motoneurones are known to discharge with a physiological variability of ~25% during voluntary contractions. Using microstimulation of single human motor axons, we have previously shown that delivering brief trains (10 pulses) of irregular stimuli, which incorporate discharge variability, generates greater contractile responses than trains of regular stimuli with identical mean frequency but zero variability. We tested the hypothesis that longer irregular (physiological) trains would produce greater contractile responses than regular (nonphysiological) trains of the same mean frequency (18 Hz) and duration (45 sec). Tungsten microelectrodes were inserted into the common peroneal nerve of human subjects, and single motor axons supplying the toe extensors (n = 14) were isolated. Irregular trains of stimuli showed greater contractile responses over identical mean frequencies in both fatigue‐resistant and fatigable motor units, but because the forces were higher the rate of decline was higher. Nevertheless, forces produced by the irregular trains were significantly higher than those produced by the regular trains. We conclude that discharge irregularity augments force production during long as well as short trains of stimulation. Long trains that integrate physiological discharge irregularity generate greater force responses than regular trains over identical mean frequencies.

Life cycle assessments (LCAs) of early-stage technologies can provide valuable insights about key drivers of emissions and aid in prioritizing research into further emissions-reduction opportunities. Despite this potential value, further development of LCA methods is required to handle the increased uncertainty, data gaps, and confidentially of early-stage data. This study presents a discussion of the life cycle carbon footprinting of technologies competing in the final round of the NRG COSIA Carbon XPRIZE competition—a US$20 million competition for teams to demonstrate the conversion of CO2 into valuable products at the scale of a small industrial pilot using consistent deployment conditions, boundaries, and methodological assumptions. This competition allowed the exploration of how LCA can be used and further improved when assessing disparate and early-stage technologies. Carbon intensity estimates are presented for two conversion pathways: (i) CO2 mineralization and (ii) catalytic conversion (including thermochemical, electrochemical, photocatalytic and hybrid process) of CO2, aggregated across teams to highlight the range of emissions intensities demonstrated at the pilot for individual life cycle stages. A future scenario is also presented, demonstrating the incremental technology and deployment conditions that would enable a team to become carbon-avoiding relative to an incumbent process (i.e. reducing emissions relative to a reference pathway producing a comparable product). By considering the assessment process across a diverse set of teams, conversion pathways and products, the study presents generalized insights about opportunities and challenges facing carbon capture and -utilization technologies in their next phases of deployment from a life cycle perspective.