Experiments to evaluate the effect of in‐season calcium (Ca) sprays on late‐season peach (Prunus persica L. Batsch cv. Calrico) were carried out for a 2‐year period. Calcium formulations (0.5% and ...1.0% in 2008 and only 0.5% tested in 2009) supplied either as CaCl2 or Ca propionate in combination with two or three adjuvants (0.05% of the nonionic surfactants Tween 20 and Break Thru, and 0.5% carboxymethylcellulose, CMC) were sprayed four to five times over the growing season. Peach mesocarp and endocarp Ca concentrations were determined on a 15‐day basis from the beginning of May until the end of June. Further tissue analyses were performed at harvest. A decreasing trend in fruit Ca concentrations over the growing season was always observed regardless of the Ca treatments. Both in 2008 and 2009, significant tissue Ca increments associated with the application of Ca‐containing sprays in combination with adjuvants were only observed in June, which may be coincident with the period of pit hardening. In 2008, both at harvest and after cold storage, the total soluble‐solids concentration (° Brix) of fruits supplied with Ca propionate (0.5% and 1.0% Ca) was always lower as compared to the rest of treatments. The application of multiple Ca‐containing sprays increased firmness at harvest and after cold storage, especially when CaCl2 was the active ingredient used. Supplying the adjuvants Tween 20 and CMC increased fruit acidity both at harvest and after cold storage. Evaluation of the development of physiological disorders after cold storage (2 weeks at 0°C) indicated a lower susceptibility of Ca‐treated fruits to internal browning. Fruits treated with multiple CaCl2‐, CMC‐, and Break Thru®‐containing sprays during the growing season were significantly less prone to the development of chilling injuries as compared to untreated peaches.
Sunfilters based on hydroxyapatite (HAp) and iron‐containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger ...free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe‐containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared, respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser‐treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near‐infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties.
Laser ablation in liquid leads to improved UV absorption.
BACKGROUND: The effect of subjecting 'Golden Reinders' apples to a low O₂ pre-treatment (LOT; 1-2% O₂) was evaluated as a strategy to decrease the rate of bitter pit (BP) incidence after standard ...cold storage (ST). Immediately after harvest, apples were stored for 10 days at 20 °C under low O₂. Thereafter, apples were cold-stored (0-4 °C) for 4 months and changes were monitored in terms of BP incidence, fruit quality traits and mineral element concentrations.RESULTS: After 4 months cold storage, LOT apples presented a 2.6-fold decrease in the rate of BP incidence (14%) versus the values obtained for standard cold-stored fruits (37% BP incidence). LOT increased flesh firmness, total soluble solids and titratable acidity as compared to the quality traits determined for cold-stored fruits. Lower cortex Ca and Mg concentrations as compared to ST apples were determined in association with LOT, 2 months after cold storage.CONCLUSION: Application of a LOT prior to cold storage may be a promising strategy to reduce the incidence of BP and preserve fruit quality, which should be further investigated.
The use of glass in structural applications has been increasing during last years. Nevertheless, the generalized use of surface-modified bearing glass is precluded by the lack of knowledge about ...their mechanical performance. This experimental investigation carries out the assessment of the fracture toughness and strength of glass subjected to laser blasting. Annealed glass and heat strengthened glass plates were subjected to mid-infrared laser surface treatment to increase the surface roughness and improve the slip resistance in wet conditions. The fracture toughness and fracture surface energy were experimentally determined from the observed radial cracks after micro-indentation with a pyramidal diamond indenter, and the results were analyzed in correlation to the laser processing conditions and the obtained surface roughness. The Weibull graph and the cumulative failure probability of the as-received and laser-modified glass were obtained by the four-point bending test.
Laser-matter interactions in laser additive manufacturing (LAM) occur on short time scales (10−6–10−3 s) and have traditionally proven difficult to characterise. We investigate these interactions ...during LAM of stainless steel SS316L and 13-93 bioactive glass powders using a custom built LAM process replicator (LAMPR) with in situ and operando synchrotron X-ray real-time radiography. This reveals a wide range of melt track solidification phenomena as well as spatter and porosity formation. We hypothesise that the SS316L powder absorbs the laser energy at its surface while the trace elements in the 13-93 bioactive glass powder absorb and remit the infra-red radiation. Our results show that a low viscosity melt, e.g. 8 mPa s for SS316L, tends to generate spatter (diameter up to 250 μm and an average spatter velocity of 0.26 m s−1) and form a melt track by molten pool wetting. In contrast, a high viscosity melt, e.g. 2 Pa s for 13-93 bioactive glass, inhibits spatter formation by damping the Marangoni convection, forming a melt track via viscous flow. The viscous flow in 13-93 bioactive glass resists pore transport; combined with the reboil effect, this promotes pore growth during LAM, resulting in a pore size up to 600 times larger than that exhibited in the SS316L sample.
Background:
The efficacy of tuned defibrillation waveforms versus the nominal fixed‐tilt waveform has been previously studied. However, the optimal membrane time constant for tuning was not known. ...The POWER (Pulsewidth Optimized Waveform Evaluation tRial) trial was designed to determine the optimal membrane time constant for programming “tuned” biphasic waveforms.
Methods:
This acute, multicenter study included 121 implantable cardioverter‐defibrillator/cardiac resynchronization therapy defibrillator patients who were randomized at implant to any two of the three membrane time constant waveforms (2.5, 3.5, and 4.5 ms). Fixed pulse widths were programmed using the measured high voltage shock impedance. The defibrillation threshold (DFT) estimates were obtained using a hybrid protocol starting with an upper limit of vulnerability estimate followed by a step‐up/step‐down ventricular fibrillation induction process.
Results:
DFT voltage was significantly lower using 3.5‐ and 4.5‐ms waveforms as compared to the 2.5‐ms waveform (P = 0.004 and 0.035, respectively). DFT voltage with both 3.5‐ and 4.5‐ms waveforms was ≤ that obtained with the 2.5‐ms waveform
in 78.5% of the cases. The mean difference in DFT voltage using the 3.5‐ms waveform and the 4.5‐ms waveform was not significant (P = 0.4). However, the 3.5‐ms waveform gave a lower DFT than the 4.5‐ms waveform in 19 patients although the reverse was true in only
nine (P = 0.02 not significant for multiple comparisons).
Conclusions:
The use of a 3.5‐ or 4.5‐ms time constant‐based waveforms had lower DFTs when compared to the 2.5‐ms waveform. This study suggests that the first defibrillation attempt at implantation should be with 3.5‐ or 4.5‐ms time constant‐based waveforms. The 3.5‐ms‐based waveform trended toward the best choice. (PACE 2012; 35:1253–1261)
Prior studies of active pectoral implantable defibrillator (ICD) lead systems demonstrated a lowering of defibrillation thresholds (DFTs) with the addition of a superior vena cava (SVC) coil. These ...studies were done on fixed-tilt waveforms where a large reduction in impedance leads to large phase duration changes.
The present study was designed to evaluate the SVC coil benefit and intercoil spacing on DFTs with a "tuned" waveform.
This prospective, multicenter study included 113 patients randomized at implant to a 17-cm and a 21-cm intercoil spacing ICD lead. DFTs were measured with SVC coil turned ON versus OFF in a random order, using an optimized binary search method.
DFT voltage (423 +/- 120 vs. 438 +/- 118 V; P = .042) and stored energy (9.8 +/- 5.6 vs. 10.2 +/- 5.8 J; P = .043) were significantly reduced with the SVC coil ON. However, intercoil distance had no significant effect on DFT voltage (437.3 +/- 115.1 vs. 407.7 +/- 123.8 V; P = .19) or stored energy (10.3 +/- 5.4 vs. 9.2 +/- 5.8 J; P = .31). Subgroup analyses showed that the dual-coil leads were most effective when placed in the high position (innominate vein-SVC junction) or when the single-coil shock impedance was > or =58 Omega, regardless of intercoil spacing.
With a tuned waveform, the addition of an SVC coil to the shocking pathway reduces DFTs, although this difference was smaller than reported previously. Intercoil distance had no significant effect on the defibrillation parameters.
Background: The maturation of the high‐voltage impedance (HVLI) of defibrillating leads has not been explored thoroughly. Since impedance influences the charge, current, and energy delivered to the ...heart in both fixed pulse‐width and fixed tilt implantable cardioverter‐defibrillator (ICD) waveforms, changes in HVLI might have an effect on the defibrillation threshold. This analysis examined the maturation of defibrillation lead HVLI.
Methods: The data were collected in 515 recipients of ICDs capable of storing high‐voltage shock diagnostics, including HVLI. Data with constant superior vena cava (SVC) coil configuration (coil ON or OFF) were collected for up to 24 months. HVLI values were recorded, plotted, and normalized by the value at implant; the percentage of patients in whom HVLI increased or decreased by ≥6 Ω was calculated, and the maturation of leads with SVC ON versus OFF was compared.
Results: A ≥6 Ω increase or decrease in HVLI was observed in 41% of patients more than 3 months after ICD implant, with the magnitudes as follows: 6–7.5 Ω change = 16%, 8–9.5 Ω= 11%, 10–11.5 Ω= 6%, and ≥12 Ω= 8%. In this subgroup, 67% of patients showed an increase in impedance, and the remaining 33% of patients showed a decrease. For ICD‐programmed SVC OFF, the right ventricular (RV) Coil‐to‐Can HVLI increased by 8 Ω after 6 weeks and did not significantly change thereafter.
Conclusions: HVLI changed significantly in 41% of leads after 3 months. The HVLI trend of the RV Coil‐to‐Can configuration appeared to be similar to the SVC Coil/Can‐to‐RV and Coil‐to‐Can configurations. Changes in HVLI of 6–12 Ω will alter the characteristics of the shock waveform and could require retuning of the waveforms to maintain adequate DFT safety margin. If re‐tuning the shock waveforms is not performed, these HVLI changes have the potential to result in elevated DFT. These HVLI changes may partially account for the 15% increase in DFT over time reported in the literature.
Introduction: Right ventricular (RV) anodal stimulation may occur in cardiac resynchronization therapy defibrillators (CRT‐D) when left ventricular (LV) pacing is configured between the LV lead and ...an electrode on the RV defibrillator lead. RV defibrillator leads can have a dedicated proximal pacing ring electrode (dedicated bipolar) or utilize the distal shocking coil as the proximal pacing electrode (integrated bipolar). This study compares the performance of integrated versus dedicated leads with respect to anodal stimulation incidence, sensing, and inappropriate ventricular tachyarrhythmia detection in patients implanted with CRT‐D.
Methods: Two hundred ninety‐two patients were randomly assigned to receive dedicated or integrated bipolar RV leads at the time of CRT‐D implantation. Patients were followed for 6 months.
Results: Patients with dedicated bipolar RV leads exhibited markedly higher rates of anodal stimulation than did patients with integrated leads. The incidence of anodal stimulation was 64% at implant for dedicated bipolar RV leads compared to 1% for integrated bipolar RV leads. The likelihood of anodal stimulation in patients with dedicated leads fell progressively during the 6‐month follow‐up (51.5%), but always exceeded the incidence of anodal stimulation in patients with integrated leads (5%). Clinically detectable undersensing and oversensing were very unusual and did not differ significantly between lead designs. There were no inappropriate ventricular tachyarrhythmia detections for either lead type.
Conclusion: Integrated bipolar RV defibrillator leads had a significantly lower incidence of RV anodal stimulation when compared to dedicated bipolar RV defibrillation leads, with no clinically detectable oversensing or undersensing, and with no inappropriate ventricular tachyarrhythmia detections for either lead type.
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