Effect of a Standardized Ginger Root Powder Regimen on Chemotherapy-Induced Nausea and Vomiting: A Multicenter, Double-Blind, Placebo-Controlled Randomized Trial.

BACKGROUND: There is substantial interest in the role of ginger as an adjuvant therapy for chemotherapy-induced nausea and vomiting (CINV). However, available evidence lacks robust methodology. OBJECTIVE: To assess the effect of adjuvant ginger compared with placebo on chemotherapy-induced nausea-related quality of life (QoL) and CINV-related outcomes. DESIGN: A parallel, double-blind, placebo-controlled randomized trial with 1:1 allocation was conducted. PARTICIPANTS/SETTING: One hundred three chemotherapy-naïve adults scheduled to receive moderately to highly emetogenic chemotherapy at two hospitals in Australia were enrolled and analyzed. INTERVENTION: Four standardized ginger capsules (totaling 84 mg/day active gingerols/shogaols), or placebo, were administered commencing the day of chemotherapy and continuing for 5 days for chemotherapy cycles 1 through 3. MAIN OUTCOME MEASURES: The primary outcome was chemotherapy-induced nausea-related QoL. Secondary outcomes were vomiting- and CINV-related QoL; anticipatory, acute, and delayed nausea and vomiting; fatigue; nutritional status; depression and anxiety; health-related QoL; and adverse events. STATISTICAL ANALYSES PERFORMED: Intention-to-treat analysis was performed. Mixed analysis of variance with repeated measures determined differences between groups. The null hypothesis was no difference between groups. After applying a Bonferroni multiple testing correction, evidence against the null hypothesis was considered at P= 0.003. RESULTS: One hundred three participants (ginger: n = 52; placebo: n = 51) were enrolled and analyzed. There was clinically relevant evidence against the null hypothesis, favoring ginger, in change scores for nausea-related QoL (F[df] = 9.34[1,101]; P = 0.003; partial η2 = 0.09), overall CINV-related QoL (F[df] = 12.26[1,101]; P < 0.001; partial η2 = 0.11), delayed nausea severity (F[df] = 9.46[1,101]; P = 0.003; partial η2 = 0.09), and fatigue (F[df] = 10.11[1,101]; P = 0.002; partial η2 = 0.09). There was a clinically meaningful lower incidence of delayed nausea and vomiting in the ginger group at Cycle 2 (53% vs 75%; P = 0.020 and 4% vs 27%; P = 0.001, respectively) and Cycle 3 (49% vs 79%; P = 0.002 and 2% vs 23%; P = 0.001, respectively). There was a clinically meaningful lower incidence of malnutrition in the ginger group at Cycle 3 (18% vs. 41%; P = 0.032) and in change scores for Patient-Generated Subjective Global Assessment (F[df)] = 4.32[1,100]; P = 0.040; partial η2 = 0.04). Change scores between groups favored ginger for vomiting-related QoL and number of vomiting episodes; however, findings were not clinically meaningful. There was no effect of ginger on anticipatory or acute CINV, health-related QoL, anxiety, or depression. No serious adverse events were reported. CONCLUSIONS: Ginger supplementation was a safe adjuvant to antiemetic medications for CINV that enhanced QoL during chemotherapy treatment. Future trials are needed to examine dose-dependent responses to verify optimal dosing regimens.

Universality of Hair as a Nucleant: Exploring the Effects of Surface Chemistry and Topography.

The ability to control crystal nucleation through the simple addition of a nucleating agent (nucleant) is desirable for a huge range of applications. However, effective nucleating agents are known for only a small number of systems, and many questions remain about the mechanisms by which they operate. Here, we explore the features that make an effective nucleant and demonstrate that the biological material hair-which naturally possesses a chemically and topographically complex surface structure-has excellent potential as an effective nucleating agent. Crystallization of poorly soluble compounds in the presence of hairs from a range of mammals shows that nucleation preferentially occurs at the cuticle step edges, while a novel microdroplet-based methodology was used to quantify the nucleating activities of different hairs. This showed that the activities of the hairs can be tuned over a wide range using chemical treatments. Analysis of the hair structure and composition using atomic force microscopy, scanning ion conductance microscopy, and X-ray photoelectron spectroscopy demonstrates that surface chemistry, surface topography, and surface charge all act in combination to create effective nucleation sites. This work therefore contributes to our understanding of heterogeneous nucleating agents and shows that surface topography as well as surface chemistry can be used in the design or selection of universal nucleating agents.

Multiscale Electrochemistry of Lithium Manganese Oxide (LiMn2O4): From Single Particles to Ensembles and Degrees of Electrolyte Wetting.

Scanning electrochemical cell microscopy (SECCM) facilitates single particle measurements of battery materials using voltammetry at fast scan rates (1 V s-1), providing detailed insight into intrinsic particle kinetics, otherwise obscured by matrix effects. Here, we elucidate the electrochemistry of lithium manganese oxide (LiMn2O4) particles, using a series of SECCM probes of graded size to determine the evolution of electrochemical characteristics from the single particle to ensemble level. Nanometer scale control over the SECCM meniscus cell position and height further allows the study of variable particle/substrate electrolyte wetting, including comparison of fully wetted particles (where contact is also made with the underlying glassy carbon substrate electrode) vs partly wetted particles. We find ensembles of LiMn2O4 particles show voltammograms with much larger peak separations than those of single particles. In addition, if the SECCM meniscus is brought into contact with the substrate electrode, such that the particle-support contact changes from dry to wet, a further dramatic increase in peak separation is observed. Finite element method modeling of the system reveals the importance of finite electronic conductivity of the particles, contact resistance, surface kinetics, particle size, and contact area with the electrode surface in determining the voltammetric waveshape at fast scan rates, while the responses are relatively insensitive to Li+ diffusion coefficients over a range of typical values. The simulation results explain the variability in voltammetric responses seen at the single particle level and reveal some of the key factors responsible for the evolution of the response, from ensemble, contact, and wetting perspectives. The variables and considerations explored herein are applicable to any single entity (nanoscale) electrochemical study involving low conductivity materials and should serve as a useful guide for further investigations of this type. Overall, this study highlights the potential of multiscale measurements, where wetting, electronic contact, and ionic contact can be varied independently, to inform the design of practical composite electrodes.

Role of Mass Transport in the Deposition, Growth, and Transformation of Calcium Carbonate on Surfaces at High Supersaturation.

We demonstrate how combined in-situ measurements and finite element method modeling can provide new insight into the relative contribution of mass transport to the growth of calcium carbonate on two model surfaces, glass and gold, under high-supersaturation conditions relevant to surface scaling. An impinging jet-radial flow system is used to create a high-supersaturated solution at the inlet of different cells: an optical microscope cell presenting a glass surface for deposition and quartz crystal microbalance (QCM) and in-situ IR spectroscopy cells, both presenting a gold surface. The approach described is quantitative due to the well-defined mass transport, and both time-lapse optical microscopy images and QCM data are analyzed to provide information on the growth kinetics of the calcite crystals. Initially, amorphous calcium carbonate (ACC), formed in solution, dominates the deposition process. At longer times, the growth of calcite is more significant and, on glass, is observed to consume ACC from the surface, leading to surface regions depleted of ACC developing around calcite microcrystals. On Au, the mass increase becomes linear with time in this region. Taken together, these microscopic and macroscopic measurements demonstrate that calcite growth has a significant component of mass transport control at high supersaturation. Finite element method (FEM) simulations of mass-transport-limited crystal growth support the strong mass transport contribution to the growth kinetics and further suggest that the observed growth must be sustained by more than just the Ca2+ and CO3 2- in solution, with dissolution/direct attachment of ACC and/or ion pairs also contributing to the growth process.

Critical Step Length as an Indicator of Surface Supersaturation during Crystal Growth from Solution.

The surface processes that control crystal growth from solution can be probed in real-time by in situ microscopy. However, when mass transport (partly) limits growth, the interfacial solution conditions are difficult to determine, precluding quantitative measurement. Here, we demonstrate the use of a thermodynamic feature of crystal surfaces-the critical step length-to convey the local supersaturation, allowing the surface-controlled kinetics to be obtained. Applying this method to atomic force microscopy measurements of calcite, which are shown to fall within the regime of mixed surface/transport control, unites calcite step velocities with the Kossel-Stranski model, resolves disparities between growth rates measured under different mass transport conditions, and reveals why the Gibbs-Thomson effect in calcite departs from classical theory. Our approach expands the scope of in situ microscopy by decoupling quantitative measurement from the influence of mass transport.

Hybrid scanning electrochemical cell microscopy-interference reflection microscopy (SECCM-IRM): tracking phase formation on surfaces in small volumes.

We describe the combination of scanning electrochemical cell microscopy (SECCM) and interference reflection microscopy (IRM) to produce a compelling technique for the study of interfacial processes and to track the SECCM meniscus status in real-time. SECCM allows reactions to be confined to well defined nm-to-µm-sized regions of a surface, and for experiments to be repeated quickly and easily at multiple locations. IRM is a highly surface-sensitive technique which reveals processes happening (very) close to a substrate with temporal and spatial resolution commensurate with typical electrochemical techniques. By using thin transparent conductive layers on glass as substrates, IRM can be coupled to SECCM, to allow real-time in situ optical monitoring of the SECCM meniscus and of processes that occur within it at the electrode/electrolyte interface. We first use the technique to assess the stability of the SECCM meniscus during voltammetry at an indium tin oxide (ITO) electrode at close to neutral pH, demonstrating that the meniscus contact area is rather stable over a large potential window and reproducible, varying by only ca. 5% over different SECCM approaches. At high cathodic potentials, subtle electrowetting is easily detected and quantified. We also look inside the meniscus to reveal surface changes at extreme cathodic potentials, assigned to the possible formation of indium nanoparticles. Finally, we examine the effect of meniscus size and driving potential on CaCO3 precipitation at the ITO electrode as a result of electrochemically-generated pH swings. We are able to track the number, spatial distribution and morphology of material with high spatiotemporal resolution and rationalise some of the observed deposition patterns with finite element method modelling of reactive-transport. Growth of solid phases on surfaces from solution is an important pathway to functional materials and SECCM-IRM provides a means for in situ or in operando visualisation and tracking of these processes with improved fidelity. We anticipate that this technique will be particularly powerful for the study of phase formation processes, especially as the high throughput nature of SECCM-IRM (where each spot is a separate experiment) will allow for the creation of large datasets, exploring a wide experimental parameter landscape.

Visualization of Ion Fluxes in Nanopipettes: Detection and Analysis of Electro-osmosis of the Second Kind.

Nanopipettes are finding increasing use as nano "test tubes", with reactions triggered through application of an electrochemical potential between electrodes in the nanopipette and a bathing solution (bath). Key to this application is an understanding of how the applied potential induces mixing of the reagents from the nanopipette and the bath. Here, we demonstrate a laser scanning confocal microscope (LSCM) approach to tracking the ingress of dye into a nanopipette (20-50 nm diameter end opening). We examine the case of dianionic fluorescein under alkaline conditions (pH 11) and large applied tip potentials (±10 V), with respect to the bath, and surprisingly find that dye ingress from the bath into the nanopipette is not observed under either sign of potential. Finite element method (FEM) simulations indicate this is due to the dominance of electro-osmosis in mass transport, with electro-osmotic flow in the conventional direction at +10 V and electro-osmosis of the second kind acting in the same direction at -10 V, caused by the formation of significant space charge in the center of the orifice. The results highlight the significant deviation in mass transport behavior that emerges at the nanoscale and the utility of the combined LSCM and FEM approach in deepening understanding, which in turn should promote new applications of nanopipettes.

Electrochemistry, ion adsorption and dynamics in the double layer: a study of NaCl(aq) on graphite.

Graphite and related sp2 carbons are ubiquitous electrode materials with particular promise for use in e.g., energy storage and desalination devices, but very little is known about the properties of the carbon-electrolyte double layer at technologically relevant concentrations. Here, the (electrified) graphite-NaCl(aq) interface was examined using constant chemical potential molecular dynamics (CµMD) simulations; this approach avoids ion depletion (due to surface adsorption) and maintains a constant concentration, electroneutral bulk solution beyond the surface. Specific Na+ adsorption at the graphite basal surface causes charging of the interface in the absence of an applied potential. At moderate bulk concentrations, this leads to accumulation of counter-ions in a diffuse layer to balance the effective surface charge, consistent with established models of the electrical double layer. Beyond ∼0.6 M, however, a combination of over-screening and ion crowding in the double layer results in alternating compact layers of charge density perpendicular to the interface. The transition to this regime is marked by an increasing double layer size and anomalous negative shifts to the potential of zero charge with incremental changes to the bulk concentration. Our observations are supported by changes to the position of the differential capacitance minimum measured by electrochemical impedance spectroscopy, and are explained in terms of the screening behaviour and asymmetric ion adsorption. Furthermore, a striking level of agreement between the differential capacitance from solution evaluated in simulations and measured in experiments allows us to critically assess electrochemical capacitance measurements which have previously been considered to report simply on the density of states of the graphite material at the potential of zero charge. Our work shows that the solution side of the double layer provides the more dominant contribution to the overall measured capacitance. Finally, ion crowding at the highest concentrations (beyond ∼5 M) leads to the formation of liquid-like NaCl clusters confined to highly non-ideal regions of the double layer, where ion diffusion is up to five times slower than in the bulk. The implications of changes to the speciation of ions on reactive events in the double layer are discussed.