Application of an accelerometer in adjusting parameters and detecting characteristics in the pacemaker rate response.

Objective.To study the application of an accelerometer in adjusting the parameters, setting the sensor indicated rate (SIR) and detecting characteristics in the pacemaker (PM) rate response.Approach.Three-axis (GT9X Link-type) accelerometers were positioned on the waist and chest in 33 participants implanted with rate responsive PMs while wearing an ambulatory ECG recorder (Holter). During the walking test, by collecting vertical axis (Axis-1) activity intensity counts, Axis-1' metabolic equivalent of energy (METaxis-1) and its expected heart rate (HRmet-axis1) were calculated by the relevant equations, and on the basis of the HRmet-axis1as the target heart rate, the SIR was set by programming the rate response slope parameter. During the following daily walking activity, the physical activity parameters and Holter ECG was recorded continuously. After the end of the whole test the analysis on these data recorded was performed retrospectively.Main results.After completing the SIR setting, in 24 participants with complete ventricular pacing the comparison between HRmet-axis1(92.5 ± 7.8 BPM) and the HRvp-Holter(94.0 ± 10.5 BPM) showed no statistical difference (ΔHR: 1.25 ± 6.69 BPM,P: 0.568) during the last one walking test, and there was also no significant difference (ΔHR: 2.8 ± 7.1 BPM,P: 0.398) between the HRmet-axis1(90.7 ± 7.1 BPM) and HRvp-Holter(93.4 ± 10.3 BPM) during daily walking activity. In addition, in the data of 108 time intervals selected during the daily walking activities in the abovementioned 24 participants, METaxis-1and HRvp-Holtercorrelation analysis showed good correlation and the regression equation was HR = 12.4 × MET±43.1 (P<0.0001).Significance.An accelerometer can play an important role in adjusting parameters, setting the SIR and detecting characteristics in the PM rate response.

Deposition amount effects on the microstructure of ion-beam-sputtering grown Mn0.03Ge0.97 quantum dots for spintronic applications.

Here, a relative simpler and lower cost method, ion beam sputtering deposition was applied to fabricate diluted magnetic Mn x Ge1-x quantum dots (QDs). The effects of Ge-Mn co-deposition amount on the morphology and crystallization of Mn0.03Ge0.97 QDs were investigated systematically by employing the atomic force microscopy and Raman spectroscopy techniques. It can be seen that the morphology, density, and crystallinity of Mn0.03Ge0.97 QDs exhibit unique evolution processes with the increase of Ge-Mn co-sputtering amount. The optimal deposition amount for realizing well size-uniform, large-aspect-ratio, and high-density QDs is also determined. The unique evolution route of diluted magnetic semiconductor QDs and the amount of co-sputtering are also discussed sufficiently.

Optical properties of D and S defects induced by Si+/Ni+ ions co-implanting into Si films on insulator.

In the article, we report the photoluminescence (PL) properties of D and S defects induced by Si+/Ni+ ions co-implanting into the top Si film of the silicon-on-insulator (SOI) wafer. Variable-temperature PL spectra of these co-implanted SOI samples indicate that the light emitting from the D defects can be observed as high as 273 K. In comparison with the other ion-implantation, the Si+/Ni+ ion-co-implantation optimizes luminescent temperature stability of the both D and S defects and purifies the S defect type in silicon then effectively restrains the spectral broadening of the S-line in PL spectra. The depth distribution of the D and S defects along the normal direction of SOI surface at the corresponding ion-implantation energy has been well depicted by detecting the PL signals of the layer-by-layer etched SOI surface, respectively. These results provide valuable information to fabricate SOI-based infrared light sources for optical fiber communications.

Direct Experimental Evidence of Biomimetic Surfaces with Chemical Modifications Interfering with Adhesive Protein Adsorption.

Current approaches to dealing with the worldwide problem of marine biofouling are to impart chemical functionality to the surface or utilize microtopography inspired by nature. Previous reports have shown that only introducing a single method may not resist adhesion of mussels or inhibit biofouling in static forms. While it is promising to integrate two methods to develop an effective antifouling strategy, related basic research is still lacking. Here, we have fabricated engineered shark skin surfaces with different feature heights and terminated with different chemical moieties. Atomic force microscopy (AFM) with a modified colloid probe technique and quartz crystal microbalance with a dissipation n (QCM-D) monitoring method have been introduced to directly determine the interactions between adhesive proteins and functionalized surfaces. Our results indicate that the adhesion strength of probe-surface decreases with increasing feature height, and it also decreases from bare Si surface to alkyl and hydroxyl modification, which is attributed to different contact area domains and interaction mechanisms. Combining biomimetic microtopography and surface chemistry, our study provides a new perspective for designing and developing underwater anti-fouling materials.

Self-Assembly Behavior of Ultrahighly Charged Amphiphilic Polyelectrolyte on Solid Surfaces.

The adsorption process of a geminized amphiphilic polyelectrolyte, comprising double elementary charges and double hydrophobic tails in each repeat unit (denoted as PAGC8), was investigated and characterized by means of quartz crystal microbalance with dissipation (QCM-D), ellipsometry, and atomic force microscopy (AFM). By comparison, the self-assembly behaviors of a traditional polyelectrolyte without hydrophobic chains (denoted as PASC1) and an amphiphilic polyelectrolyte with a single hydrophilic headgroup and hydrophobic tail in each repeat unit (denoted as PASC8) at the solid/liquid interface were also investigated in parallel. A two-regime buildup was found in both amphiphilic systems of PASC8 and PAGC8, where the first regime was dependent on electrostatic interactions between polyelectrolytes and oppositely charged substrates, and the rearrangements of the preadsorbed chains and their aggregation behaviors on surface dominated the second regime. Furthermore, it was found that the adsorbed amount and conformation changed as a function of the charge density and bulk concentrations of the polyelectrolytes. The comparison of the adsorbed mass obtained from QCM-D and ellipsometry allowed calculating the coupling water content which reached high values and indicated a flexible aggregate conformation in the presence of PAGC8, resulting in controlling the suspension stability even at an extremely low concentration. In order to provide an insight into the mechanism of the suspension stability of colloidal dispersions, we gave a further explanation with respect to the interactions between surfaces in the presence of the geminized polyelectrolyte.

Supercritically exfoliated ultrathin vanadium pentoxide nanosheets with high rate capability for lithium batteries.

Ultrathin V2O5 nanosheets were successfully prepared through supercritical solvothermal reaction followed by annealing treatment. The formation of ultrathin nanosheets is owing to Ostwald ripening and the effect of supercritical fluids. As cathode material for lithium batteries, the ultrathin V2O5 nanosheets exhibit a capacity of 108 mA h g(-1) at a high rate of up to 10 C at 2.4-4 V and excellent cyclability with little capacity loss after 200 cycles. The enhanced rate performance is attributed to the shortened diffusion distance and the increased electrode-electrolyte contact area of the ultrathin nanosheet structure. It is also demonstrated that the supercritical solvothermal method is effective and facile to scalably synthesize ultrathin nanomaterials for lithium batteries.