Additional Mass Research Articles

Determination of 222 pesticide residues in olive oil by fully automatic QuEChERS pre-treatment instrument coupled with gas chromatography-quadrupole-time-of-flight mass spectrometry

Pesticide residues may be present in olive oil because pesticides are applied to olive trees during their cultivation and growth for pest prevention and some of these pesticides are not easily degraded. Studies on pesticide residues in olive oil have mainly focused on the detection of single types of pesticide residues, and reports on the simultaneous detection of multiple pesticide residues are limited. At present, hundreds of pesticides with different polarities and chemical properties are used in practice. In this study, an analytical method based on fully automatic QuEChERS pretreatment instrument coupled with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF-MS) was established for the rapid determination of 222 pesticide residues in olive oil. The effects of acetonitrile acidification concentration, n-hexane volume, oscillation time, centrifugation temperature, and purification agent on the determination of the 222 pesticide residues were investigated. First, ions with good responses and no obvious interference were selected for quantification and characterization. The purification process was then developed by setting the parameters of the fully automatic QuEChERS pretreatment instrument to optimal values. The sample was extracted with acetonitrile containing 2% formic acid, and the supernatant was purified by centrifugation in a centrifuge tube containing 400 mg N-propylethylenediamine (PSA), 400 mg octadecylsilane-bonded silica gel (C18), and 1200 mg anhydrous magnesium sulfate. The purified solution was blown dry with nitrogen and then fixed with ethyl acetate for instrumental analysis. Finally, a matrix standard solution was used for quantification. The method was validated in terms of matrix effects, linear ranges, limits of detection (LODs) and quantification (LOQs), accuracies, and precisions. The results showed that 86.04% of the 222 pesticides had linear ranges of 0.02-2.00 μg/mL, 10.81% had linear ranges of 0.10-2.00 μg/mL, and 3.15% had linear ranges of 0.20-2.00 μg/mL. The pesticide residues showed good relationships within their respective linear ranges, and the correlation coefficients (R2) were greater than 0.99. The LODs of all tested pesticides ranged from 0.002 to 0.050 mg/kg, and their LOQs ranged from 0.007 to 0.167 mg/kg. Among the 222 pesticides determined, 170 pesticides had LOQs of 0.007 mg/kg while 21 pesticides had LOQs of 0.017 mg/kg. At the three spiked levels of 0.2, 0.5, and 0.8 mg/kg, 79.58% of all tested pesticides had average recoveries of 70%-120% while 65.92% had average recoveries of 80%-110%. In addition, 93.54% of all tested pesticides had relative standard deviations (RSDs, n=6)<10% while 98.35% had RSDs (n=6)<20%. The method was applied to 14 commercially available olive oil samples, and seven pesticides were detected in the range of 0.0044-0.0490 mg/kg. The residues of fenbuconazole, chlorpyrifos, and methoprene did not exceed the maximum limits stated in GB 2763-2021. The maximum residual limits of molinate, monolinuron, benalaxyl, and thiobencarb have not been established. The method utilizes the high mass resolution capability of TOF-MS, which can improve the detection throughput while ensuring good sensitivity. In addition, high-resolution and accurate mass measurements render the screening results more reliable, which is necessary for the high-throughput detection of pesticide residues. The use of a fully automatic QuEChERS instrument in the pretreatment step reduces personnel errors and labor costs, especially when a large number of samples must be processed, thereby offering significant advantages over other approaches. Moreover, the method is simple, rapid, sensitive, highly automatable, accurate, and precise. Thus, it meets requirements for the high-throughput detection of pesticide residues in olive oil and provides a reference for the development of detection methods for pesticide residues in other types of oils as well as the automatic pretreatment of complex matrices.

A Flexible Ultrasound Transducer Array Patch

Ultrasound is a non-destructive and safe testing technology that can be used for structural health monitoring and biomedical electronics. Current rigid probes have limitations such as difficulty in fitting to curved surfaces, heavy additional mass and large size, which make it difficult to be fully utilized in practical applications. To tackle this issue, an innovative flexible sensing technology has been developed, employing flexible materials such as flexible polymer substrates combined with a novel preparation process that allows the entire sensing network to be integrated onto the structure to be measured. This adaptable approach proves suitable for a diverse range of applications. In this work, a flexible ultrasound transducer array patch designed for attachment to curved surfaces for ultrasound detection is introduced. We proposed a simple fabrication process, and validate the device performance through software simulation and experimentation. The size of each transducer element is 2 mm × 2 mm × 0.6 mm and the overall size of the device is 28 mm × 28 mm × 0.9 mm, with an array of 3 × 4.

Design and Performance Assessment of Base Isolated Structures Supplemented with Vibration Control Systems

This paper investigates the implementation of supplemental vibration control systems (VCS) in base isolated (BI) structures, to improve their dynamic performance. More specifically, the aim of the VCS is to reduce the base displacement demand of BI structures, and at the same time mitigate the superstructure seismic responses. The purpose of the examined VCS is dual, and for this reason a multi-objective optimization methodology is formulated for the design of the VCS. The examined vibration absorbers include modifications of the KDamper concept. The KDamper is an extension of the traditional Tuned Mass Damper (TMD), and introduces a negative stiffness (NS) element to the additional oscillating mass of the TMD. The generated NS force is exactly in phase with the inertia force of the added mass, thus, artificially amplifying it. This way, lighter configurations are possible with an enhanced damping behavior. These VCS are designed based on engineering criteria and manufacturing constraints, while the excitation input used in the multi-objective optimization procedure is selected from a dataset of artificial accelerograms, designed to be spectrum-compatible with the EC8 design acceleration response spectrum. The effectiveness of the examined VCS is also assess with real near-fault earthquake records, and a comparison is performed with TMD-based VCS having 50 times larger additional masses. The numerical results demonstrate the superiority of the KDamper-based VCS in improving the dynamic behavior of BI structures over other mass-related systems (TMD).

Enhancing seismic resilience of nonlinear structures through optimally designed additional mass dampers

Reducing dynamic responses in structures subjected to external excitations like earthquakes and strong winds is crucial for ensuring safety and serviceability. Conventional tuned mass dampers (CTMDs) have limitations in mitigating nonlinear vibrations efficiently. This research proposes the use of additional mass dissipation (AMD) devices to control nonlinear dynamic responses more effectively than CTMDs. The AMD concept involves installing an auxiliary mass–damper system atop the primary structure. An analytical approach is developed to determine the optimal design parameters of AMDs for linear and nonlinear single-degree-of-freedom systems using H2 and H∞ optimization techniques. Transfer function and harmonic balance methods are employed to evaluate the dynamic response reduction capabilities. Compared to optimally designed CTMDs, the proposed H2 and H∞ optimized AMDs demonstrate remarkably superior vibration mitigation achieving up to 77 % and 73.71 % greater reductions in dynamic responses, respectively. The Newmark-beta numerical validation confirms AMDs outperforming CTMDs by 16.06 % in minimizing structural vibrations. The novel AMD concept, coupled with the derived optimal design formulations, offers a highly effective vibration control strategy for both linear and nonlinear structural systems under harmonic and random excitations. This analytical solution paves the way for implementing AMDs in practice to enhance structural safety and longevity against external dynamic loads.

Low-frequency vibration attenuation of metamaterial sandwich plate with lever-type inertial amplified resonators

The utilization of sandwich plate structures is widespread across diverse engineering fields owing to their advantageous high stiffness-to-weight ratio properties. However, these lightweight and thin-walled structures commonly encounter challenges related to inadequate vibration performance in the low-frequency range, imposing significant limitations on their applications. This paper thereby presents a design for a metamaterial sandwich plate that incorporates lever-type inertial amplified resonators (IA-MSP) to achieve a low-frequency bandgap and effective vibration attenuation capability. The bandgap characteristics and vibration behavior of the IA-MSP are comprehensively studied through an integrated approach involving theoretical analysis, numerical simulations, and experimental studies. The dynamic model of the IA-MSP is mathematically formulated, theoretically elucidating the underlying inertial amplification mechanism within the proposed metamaterial sandwich plates. The investigation on vibration transmission is conducted to analyze the vibration attenuation performance of the IA-MSP, utilizing both numerical simulations and experimental methods. The findings reveal that lever-type resonators amplify the mass motion, thereby enhancing the effective mass of the system and leading to a reduction in the frequency associated with the coupled mode of the bandgap. This amplification facilitates the attainment of a low-frequency bandgap without the need for utilizing the inclusion of additional centralized mass or heavy local resonators. By altering the lever ratio R of the lever-type inertial amplified resonators, precise fine-tuning and optimization of the low-frequency bandgaps are achievable. Compared with traditional metamaterial sandwich plates with local resonators (LR-MSP) featuring identical geometrical and material characteristics, the proposed IA-MSP characterized by an R-value of 2 exhibits boundary frequencies that are half of those observed in the LR-MSP. With an increase in the lever ratio R of the IA-MSP, a noticeable trend emerges a decrease in the lower boundary frequency, accompanied by a corresponding shift of the bandgap towards lower frequencies. The present study's outcomes are anticipated to hold significant promise in the realm of sandwich plate design, with a specific focus on furnishing vibration attenuation capabilities at lower frequencies.

Centres of rigidity in multi-storey asymmetric diaphragm systems for eigenmodal vibrations

In this paper a general methodology is proposed for calculating the centres of rigidity of multi-storey asymmetric buildings subjected to eigenmodal vibrations with possible modal damping. The methodology is applicable to any building with horizontal diaphragms, even to those with complex topology, possible coupling of diaphragms and existence of additional masses out of diaphragms, assuming linearly elastic behaviour. The methodology is presented in a simple formulation, using only the stiffness resisting diaphragm forces during these vibrations. The methodology uses the results of two eigenmodes obtained by eigenmodal analysis, which can be carried out by a variety of standard programs for dynamic analysis of structures, along with a small post-processing effort that can be easily programmed in a worksheet. A numerical example presents the individual steps of the proposed methodology, while two additional numerical examples demonstrate it's simplicity and efficiency. It is shown that the centres of rigidity lie on a fixed position in each diaphragm for each proper pair of eigenmodal vibrations, irrespective of the existence of modal damping, and therefore they can be included in the basic dynamic characteristics of the building.

Controlling chaotic vocal fold oscillations in the numerical production of vowel sounds

Lumped mass models have been studied in depth to unveil the complex nonlinear physics of phonation. Even in the case of simple symmetric models, slight changes in muscle restoring forces or excessive subglottal pressure can cause abnormal or even chaotic vocal fold oscillations. In a recent work, it was shown that it was possible to device a theoretical pacemaker for phonation that could render the chaotic motion regular again. This consisted of attaching an additional mass–spring–damper system to the vocal fold model, the damping of which could be adjusted according to an altering energy chaos control strategy. The chaos of phonation is low-dimensional and one may wonder whether it has a profound effect in voice production and, if so, whether the proposed phonation pacemaker could compensate for it. For this purpose, we compute the time evolution of the glottal volume velocity generated by normal, chaotic and controlled oscillations of the vocal folds and convolve it with the impulse response of magnetic resonance imaging (MRI) geometries of the human vocal tract, corresponding to the vowels /ɑ/, /i/ and /u/. The impulse response for each vowel is obtained from the solution of the wave equation by the finite element method, when a Gaussian pulse is prescribed as a boundary condition in the glottis of the vocal tract. It will be demonstrated that the chaotic vibration of the vocal folds severely distorts the vowel sounds and that the proposed control strategy is able to recover with high quality the vowels produced in normal phonation. Audiovisual files are provided to support the objective results of the phenomena in terms of spectral and time analysis of the train of glottal pulses generated by the vocal folds and the produced vowel sounds.

Effects of root-applied biochar on soil nitrogen transformation and root nitrogen metabolism of cucumber seedlings in facility continuous cropping soils.

The problem of soil barrier caused by excessive accumulation of nitrogen is common in continuous cropping soil of facility agriculture. To investigate the modulating effects of biochar amendment on soil nitrogen transformation in greenhouse continuous cropping systems, we conducted a pot experiment with two treatments, no biochar addition (CK) and 5% biochar addition (mass ratio). We analyzed the effects of biochar addition on soil microbial community structure, abundances of genes functioning in nitrogen cycling, root growth and nitrogen metabolism-related genes expressions of cucumber seedlings. The results showed that biochar addition significantly increased plant height, root dry mass, total root length, root surface area, and root volume of cucumber seedlings. Rhizosphere environment was improved, which enhanced root nitrogen absorption by inducing the up-regulation of genes expressions related to plant nitrogen metabolism. Biochar addition significantly increased soil microbial biomass nitrogen, nitrate nitrogen, and nitrite nitrogen contents. The abundances of bacteria that involved in nitrogen metabolism, including Proteobacteria, Cyanobacteria, and Rhizobiales (soil nitrogen-fixing bacteria), were also significantly improved in the soil. The abundances of genes functioning in soil nitrification and nitrogen assimilation reduction, and the activities of enzymes involved in nitrogen metabolisms such as hydroxylamine dehydrogenase, nitronate monooxygenase, carbonic anhydrase were increased. In summary, biochar addition improved soil physicochemical properties and microbial community, and affected soil nitrogen cycling through promoting nitrification and nitrogen assimilation. Finally, nitrogen adsorption capacity and growth of cucumber plant was increased.

Dynamics of axially moving viscoelastic panels immersed in fluid

The vibration of axially moving panels immersed in fluid are widely concerned in engineering problems. In this paper, free vibration characteristics and dynamic stabilities of an axially moving viscoelastic panel immersed in fluid are investigated. The governing equation is given by applying the generalized extended Hamilton principle. The axial tension per unit width is related to the axial speed and the axial acceleration, changing continuously in the axial direction, which is the innovation point and key problem of this paper. However, they were independent of each other in most previous studies. The fluid is assumed to be an ideal liquid, that is, inviscid, homogeneous and incompressible. By using the velocity potential function, the Bernoulli equation, the dynamic pressure and the boundary conditions of the fluid are derived and incorporated into the governing equation in the form of an additional mass. The Galerkin method is used to discretize the governing equation and convert it into a matrix form. The influences of the truncation order numbers and the immersion depths on the first four natural frequencies are analyzed. We found an interesting phenomenon that the fluid has an effect on both the inertia term and the damping term of the system and the effect of damping force generated by fluid is greater than that of inertia. Another innovation is that the immersion depth has little effect on the natural frequency. Moreover, the subharmonic resonance and the combination resonance are analyzed by using the averaging method. The influences of system parameters including truncation order numbers, axially supported stiffness parameters, viscoelasticity coefficients, mean axial speeds, fluids and immersion depth on the stability boundaries are considered. The stability boundaries of three models, namely the vacuum model, the material derivative model, and the partial derivative model, are compared. The results show that the material derivative model is more reasonable. The results are verified by the Runge-Kutta algorithm. The results of the analytical and numerical methods of the subharmonic and combination resonances are in good agreement with each other. In this paper, the dynamic stability of an axially moving viscoelastic panel immersed in fluid is studied by means of the average method. It extends the application range of the averaging method and provides a reference for the study of axially moving structures immersed in fluid.

Analytical optimization and performance evaluation of non-traditional tuned mass damper for stochastic base excited structures considering dual solutions

Compared with traditional tuned mass damper (TMD), non-traditional tuned mass damper (NTMD) has higher damping efficiency in some conditions. Nevertheless, the analytical optimization problem of NTMD has not been well solved; especially, multiple optimal solutions are not discussed. In this study, the closed-form optimal expressions of the NTMD using tuning stiffness are derived based on H 2 norm optimization. And the vibration mitigation performance of the NTMD is evaluated considering dual-solutions situation subjected to typical ground motion and impulse excitation. Different from solving the unique optimal frequency ratio, there exist two sets of optimal stiffness and damping ratio derived using tuned spring elements for given mass ratio, and the effective mass ratio is also limited as 1/3. The vibration mitigation or isolation performance and robustness of H 2 optimized NTMD with higher stiffness ratio are far superior to NTMD with lower stiffness ratio. NTMD using larger optimal tuning stiffness ratio also can be seen as an optimized form of Maxwell model using additional mass. Hence, using a large stiffness, namely, a large frequency ratio to design NTMD is recommended, which is different from traditional TMD. The case of NTMD with large stiffness can be adopted when the demands of practical engineering are not met using the optimal parameters of small stiffness. And a compromise scheme can also be provided, which are the combination with a larger mass ratio but is less than the maximum limit value 1/3 and a not very large stiffness ratio but is exceeded 0.5 according to demands of practical engineering.

Numerical and Experimental Study of Low-Frequency Membrane Damper for Tube Vibration Suppression

In modern days, low-frequency vibration is still challenging to suppress due to its high vibrational energy. A typical suppression method is to increase the object’s mass to reduce the amplitude of the vibration, but such a way is unsuitable in many cases. Membrane dampers can potentially eliminate the limitation and offer lightweight and compact damper. The idea is to decrease the stiffness and add additional mass to increase the dissipation of the vibration energy. For that, the membrane and an extra mass made of silicone rubber were used for the damper. Finite element eigenfrequency simulation showed the transformation of each mode to the damper mode, where the tube displacement was zero. Also, it showed the bandgap between modes in the frequency range from 106 Hz to 158 Hz. The experimental verification of clamped from both ends of the tube showed the predicted bandgap and absence of the resonance peak of the bare tube. Overall, the membrane damper showed good efficiency in extremely low frequencies and seems promising for vibration suppression.

The use of wearable resistance and weighted vest for sprint performance and kinematics: a systematic review and meta-analysis

Wearable resistance (WR) and weighted vests (WV) can be used in almost all training conditions to enhance sprint performance; however, positioning and additional mass are different in WV and WR strategies, affecting performance and kinematics differently. We aimed to systematically review the literature, searching for intervention studies that reported the acute or chronic kinematic and performance impact of WV and WR and comparing them. We analyzed Pubmed, Embase, Scopus, and SPORTDiscuss databases for longitudinal and cross-over studies investigating sprint performance or kinematics using an inverse-variance with a random-effect method for meta-analysis. After the eligibility assessment, 25 studies were included in the meta-analysis. Cross-over WR and WV studies found significantly higher sprint times and higher ground contact times (CT) compared to unloaded (UL) conditions. However, WR presented a lower step frequency (SF) compared to UL, whereas WV presented a lower step length (SL). Only one study investigated the chronic adaptations for WR, indicating a superiority of the WR group on sprint time compared to the control group. However, no difference was found chronically for WV regarding sprint time, CT, and flight time (FT). Our findings suggest that using WV and WR in field sports demonstrates overload sprint gesture through kinematic changes, however, WR can be more suitable for SF-reliant athletes and WV for SL-reliant athletes. Although promising for chronic performance improvement, coaches and athletes should carefully consider WV and WR use since there is no supporting evidence that WV or WR will impact sprint performance, CT, and FT.

Sound transmission loss of vertical building partitions designed to meet shear structural requirements

Vertical partitions often include structural building elements designed to meet shear requirements. Shear partitions are designed to resist lateral load due to wind or seismic activity and are required in many regions throughout North America. Nightingale et al. completed a 70-assembly series quantifying the effect of shear OSB on the sound transmission loss (STL) of both wood- and steel-framed single-stud assemblies in the National Research Council Canada (NRCC) research report NRCC-45018. This research study builds on the NRCC research with a test of over 200 wood and steel assembly partitions. This research study includes single-, staggered-, and double-stud framing as well as various forms of shear treatment such as OSB Plywood installed on one or both sides of the partition, attachment with various nail attachment patterns, and steel strapping. The effect of these partition elements on the STL will be presented and discussed. Additionally, the effect of sound isolation treatment, such as additional mass, resilient channels, resilient sound isolation clips, and constrained-layer damping will be presented and discussed.

Dynamic Behavior of an Unevenly Heated Thin-Walled Parabolic Aircraft Shell Taking Into Account the Presence of Additional Mass under the Influence of a Shock Wave

Dynamic Behavior of an Unevenly Heated Thin-Walled Parabolic Aircraft Shell Taking Into Account the Presence of Additional Mass under the Influence of a Shock Wave

Sound designing classical guitars through metamaterials

An approach is presented to alter the sound of a classical guitar using a metamaterial structure. By adding additional masses using magnets in a row between the bridge and the soundhole, a bandgap of around 300 Hz appears. Alternation of magnet masses and placement determine the location and strength of the bandgap. A similar approach was presented with a frame drum [R. Bader, J. L. Fischer, M. Münster, and P. Kontopidis, “Metamaterials in musical acoustics: A modified frame drum,” JASA 145(5), 3086–3094 (2019)]. There, the lower and upper limits of the bandgap are caused by the relations between the frequency wavelength and the magnet distances. With the guitar, the bandgap is caused by a shifting and attenuation of modes. Interestingly, the added masses cause a decrease in the guitar top plate mode frequencies, which is similar to membrane behavior and contrary to the expectancy of a plate. Such a guitar sound is unique due to the strong bandgap and cannot be achieved with typical alternations of changed fan bracing or top plate thickness. Magnets can easily be applied by guitarists within minutes and, therefore, qualify as a guitar sound design chosen by players.

Design of a Simple Valveless Micropump Using Piezoelectric Actuators

Abstract An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.

Analysis of Coupled Vibration Characteristics of Linear-Angular and Parameter Identification

Abstract A steady-state sinusoidal and distortion-free excitation source is very important for the accuracy and consistency of the calibration parameters of micro-electro-mechanical systems (MEMS) inertial sensors. To solve the problem that the current MEMS inertial measurement unit (IMU) calibration device is unable to reproduce the spatial motion of linear and angular vibration coupling, research topics on the coupling vibration characteristics and parameter identification for an electromagnetic linear-angular vibration exciter are proposed. This research paper used Ampere’s law and Lorentz force to establish the analytical expressions for the electromagnetic force and electromagnetic torque of the electromagnetic linear-angular vibration exciter. Then, the main purpose of this paper is to establish uniaxial and coupled vibration electromechanical analogy models containing mechanical parameters based on the admittance-type electromechanical analogy principle, and the parameter identification model is also obtained by combining the impedance formula with the additional mass method. Finally, the validity of the coupling vibration characteristics and the parameter identification model are verified by the frequency response simulation and the additional mass method, and the relative error of each parameter identification is within 5% in this paper.

Towards human-centered AI and robotics to reduce hospital falls: finding opportunities to enhance patient-nurse interactions during toileting.

Introduction: Patients who are hospitalized may be at a higher risk for falling, which can result in additional injuries, longer hospitalizations, and extra cost for healthcare organizations. A frequent context for these falls is when a hospitalized patient needs to use the bathroom. While it is possible that "high-tech" tools like robots and AI applications can help, adopting a human-centered approach and engaging users and other affected stakeholders in the design process can help to maximize benefits and avoid unintended consequences. Methods: Here, we detail our findings from a human-centered design research effort to investigate how the process of toileting a patient can be ameliorated through the application of advanced tools like robots and AI. We engaged healthcare professionals in interviews, focus groups, and a co-creation session in order to recognize common barriers in the toileting process and find opportunities for improvement. Results: In our conversations with participants, who were primarily nurses, we learned that toileting is more than a nuisance for technology to remove through automation. Nurses seem keenly aware and responsive to the physical and emotional pains experienced by patients during the toileting process, and did not see technology as a feasible or welcomed substitute. Instead, nurses wanted tools which supported them in providing this care to their patients. Participants envisioned tools which helped them anticipate and understand patient toileting assistance needs so they could plan to assist at convenient times during their existing workflows. Participants also expressed favorability towards mechanical assistive features which were incorporated into existing equipment to ensure ubiquitous availability when needed without adding additional mass to an already cramped and awkward environment. Discussion: We discovered that the act of toileting served more than one function, and can be viewed as a valuable touchpoint in which nurses can assess, support, and encourage their patients to engage in their own recovery process as they perform a necessary and normal function of life. While we found opportunities for technology to make the process safer and less burdensome for patients and clinical staff alike, we believe that designers should preserve and enhance the therapeutic elements of the nurse-patient interaction rather than eliminate it through automation.

Ideal fracton superfluids

We investigate the thermodynamics of equilibrium thermal states and their near-equilibrium dynamics in systems with fractonic symmetries in arbitrary curved space. By explicitly gauging the fracton algebra we obtain the geometry and gauge fields that field theories with conserved dipole moment couple to. We use the resultant fracton geometry to show that it is not possible to construct an equilibrium partition function for global thermal states unless part of the fractonic symmetries is spontaneously broken. This leads us to introduce two classes of fracton superfluids with conserved energy and momentum, namely pp-wave and ss-wave fracton superfluids. The latter phase is an Aristotelian superfluid at ideal order but with a velocity constraint and can be split into two separate regimes: The U(1) fracton superfluid and the pinned ss-wave superfluid regimes. For each of these classes and regimes we formulate a hydrodynamic expansion and study the resultant modes. We find distinctive features of each of these phases and regimes at ideal order in gradients, without introducing dissipative effects. In particular we note the appearance of a sound mode for ss-wave fracton superfluids. We show that previous work on fracton hydrodynamics falls into these classes. Finally, we study ultra-dense pp-wave fracton superfluids with a large kinetic mass in addition to studying the thermodynamics of ideal Aristotelian superfluids.

Indole Alkaloid Production by the Halo Blight Bacterium Treated with the Phytoalexin Genistein.

When Pseudomonas savastanoi pv. phaseolicola, the bacterium that causes halo blight, induces hypersensitive immunity in common bean leaves, salicylic acid and phytoalexins accumulate at the site of infection. Both salicylic acid and the phytoalexin resveratrol exert antibiotic activities and toxicities in vitro, adversely disrupting the P. savastanoi pv. phaseolicola proteome and metabolism and stalling replication and motility. These efficacious properties likely contribute to the cessation of bacterial spread in beans. Genistein is an isoflavonoid phytoalexin that also accumulates during bean immunity, so we tested its antibiotic potential in vitro. Quantitative proteomics revealed that genistein did not induce proteomic changes in P. savastanoi pv. phaseolicola in the same way that salicylic acid or resveratrol did. Rather, a dioxygenase that could function to metabolize genistein was among the most highly induced enzymes. Indeed, high-throughput metabolomics provided direct evidence for genistein catabolism. Metabolomics also revealed that genistein induced the bacterium to produce indole compounds, several of which had structural similarity to auxin. Additional mass spectrometry analyses proved that the bacterium produced an isomer of the auxin indole-3-acetic acid but not indole-3-acetic acid proper. These results reveal that P. savastanoi pv. phaseolicola can tolerate bean genistein and that the bacterium likely responds to bean-produced genistein during infection, using it as a signal to increase pathogenicity, possibly by altering host cell physiology or metabolism through the production of potential auxin mimics.