Droplet slipperiness despite surface heterogeneity at molecular scale

Friction determines whether liquid droplets slide off a solid surface or stick to it. Surface heterogeneity is generally acknowledged as the major cause of increased contact angle hysteresis and contact line friction of droplets. Here we challenge this long-standing premise for chemical heterogeneity at the molecular length scale. By tuning the coverage of self-assembled monolayers (SAMs), water contact angles change gradually from about 10° to 110° yet contact angle hysteresis and contact line friction are low for the low-coverage hydrophilic SAMs as well as high-coverage hydrophobic SAMs. Their slipperiness is not expected based on the substantial chemical heterogeneity of the SAMs featuring uncoated areas of the substrate well beyond the size of a water molecule as probed by metal reactants. According to molecular dynamics simulations, the low friction of both low- and high-coverage SAMs originates from the mobility of interfacial water molecules. These findings reveal a yet unknown and counterintuitive mechanism for slipperiness, opening new avenues for enhancing the mobility of droplets.

High Voltage Cycling Stability of LiF-Coated NMC811 Electrode

The development of LiNi0.8Mn0.1Co0.1O2 (NMC811) as a cathode material for high-energy-density lithium-ion batteries (LIBs) intends to address the driving limitations of electric vehicles. However, the commercialization of this technology has been hindered by poor cycling stability at high cutoff voltages. The potential instability and drastic capacity fade stem from irreversible parasitic side reactions at the electrode-electrolyte interface. To address these issues, a stable nanoscale lithium fluoride (LiF) coating is deposited on the NMC811 electrode via atomic layer deposition. The nanoscale LiF coating diminishes the direct contact between NMC811 and the electrolyte, suppressing the detrimental parasitic reactions. LiF-NMC811 delivers cycling stability superior to uncoated NMC811 with high cutoff voltage for half-cell (3.0-4.6 V vs Li/Li+) and full-cell (2.8-4.5 V vs graphite) configurations. The structural, morphological, and chemical analyses of the electrodes after cycling show that capacity decline fundamentally arises from the electrode-electrolyte interface growth, irreversible phase transformation, transition metal dissolution and crossover, and particle cracking. Overall, this work demonstrates that LiF is an effective electrode coating for high-voltage cycling without compromising rate performance, even at high discharge rates. The findings of this work highlight the need to stabilize the electrode-electrolyte interface to fully utilize the high-capacity performance of NMC811.

The effect of the pyrolysis temperature and biomass type on the biocarbons characteristics

The conversion of biomass and natural wastes into carbon-based materials for various applications such as catalysts and energy-related materials is a fascinating and sustainable approach emerged during recent years. Precursor nature and characteristics are complex, hence, their effect on the properties of resulting materials is still unclear. In this work, we have investigated the effect of different precursors and pyrolysis temperature on the properties of produced carbon materials and their potential application as negative electrode materials in Li-ion batteries. Three biomasses, lignocellulosic brewery spent grain from a local brewery, catechol-rich lignin and tannins, were selected for investigations. We show that such end-product carbon characteristic as functional and elemental composition, porosity, specific surface area, defectiveness level, and morphology strictly depend on the precursor composition, chemical structure, and pyrolysis temperature. The electrochemical characteristics of produced carbon materials correlate with the characteristics of the produced materials. A higher pyrolysis temperature is shown to be favourable for production of carbon material for the Li-ion battery application in terms of both specific capacity and long-term cycling stability.

Facile Fabrication of Ni9 S8 /Ag2 S Intertwined Structures for Oxygen and Hydrogen Evolution Reactions

Here, we report the fabrication of the unique intertwined Ni₉ S₈ /Ag₂ S composite structure with hexagonal shape from their molecular precursors by one-pot thermal decomposition. Various spectroscopic and microscopic techniques were utilized to confirm the Ni₉ S₈ /Ag₂ S intertwined structure. Powder X-ray Powder Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis suggest that there is an enrichment of Ni₉ S₈ phase in Ni₉ S₈ /Ag₂ S. The presence of Ag₂ S in Ni₉ S₈ /Ag₂ S improves the conductivity by reducing the interfacial energy and charge transfer resistance. When Ni₉ S₈ /Ag₂ S is employed as an electrocatalyst for electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity, it requires a low overpotential of 152 mV for HER and 277 mV for OER to obtain the geometrical current density of 10 mA cm^-2 , which is definitely superior to that of its components Ni₉ S₈ and Ag₂ S. This work provides a simple design route to develop an efficient and durable electrocatalyst with outstanding OER and HER performance and the present catalyst (Ni₉ S₈ /Ag₂ S) deserves as a potential candidate in the field of energy conversion systems.

Dumbbell-Shaped Ternary Transition-Metal (Cu, Ni, Co) Phosphate Bundles: A Promising Catalyst for the Oxygen Evolution Reaction

Development of economical and high-performance electrocatalysts for the oxygen evolution reaction (OER) is of tremendous interest for future applications as sustainable energy materials. Here, a unique member of efficient OER electrocatalysts has been developed based upon structurally versatile dumbbell-shaped ternary transition-metal (Cu, Ni, Co) phosphates with a three-dimensional (3D) (Cu₂(OH)(PO₄)/Ni₃(PO₄)₂·8H₂O/Co₃(PO₄)₂·8H₂O) (CNCP) structure. This structure is prepared using a simple aqueous stepwise addition of metal ion source approach. Various structural investigations demonstrate highly crystalline nature of the composite structure. Apart from the unique structural aspect, it is important that the CNCP composite structure has proved to be an excellent electrocatalyst for OER performance in comparison with its binary or constituent phosphate under alkaline and neutral conditions. Notably, the CNCP electrocatalyst displays a much lower overpotential of 224 mV at a current density of 10 mA cm^-2 and a lower Tafel slope of 53 mV dec^-1 with high stability in alkaline medium. In addition, X-ray photoelectron spectroscopy analysis suggested that the activity and long-term durability for the OER of the ternary 3D metal phosphate are due to the presence of electrochemically dynamic constituents such as Ni and Co and their resulting synergistic effects, which was further supported by theoretical studies. Theoretical calculations also reveal that the incredible OER execution was ascribed to the electron redistribution set off in the presence of Ni and Cu and the most favorable interaction between the *OOH intermediate and the active sites of CNCP. This work may attract the attention of researchers to construct efficient 3D ternary metal phosphate catalysts for various applications in the field of electrochemistry.

Tuning of Emission Wavelength of CaS:Eu by Addition of Oxygen Using Atomic Layer Deposition

Atomic layer deposition (ALD) technology has unlocked new ways of manipulating the growth of inorganic materials. The fine control at the atomic level allowed by ALD technology creates the perfect conditions for the inclusion of new cationic or anionic elements of the already-known materials. Consequently, novel material characteristics may arise with new functions for applications. This is especially relevant for inorganic luminescent materials where slight changes in the vicinity of the luminescent centers may originate new emission properties. Here, we studied the luminescent properties of CaS:Eu by introducing europium with oxygen ions by ALD, resulting in a novel CaS:EuO thin film. We study structural and photoluminescent properties of two different ALD deposited Eu doped CaS thin films: Eu(thd)₃ which reacted with H₂S forming CaS:Eu phosphor, or with O₃ originating a CaS:EuO phosphor. It was found that the emission wavelength of CaS:EuO was 625.8 nm whereas CaS:Eu was 647 nm. Thus, the inclusion of O²⁻ ions by ALD in a CaS:Eu phosphor results in the blue-shift of 21.2 nm. Our results show that ALD can be an effective way to introduce additional elements (e.g., anionic elements) to engineer the physical properties (e.g., inorganic phosphor emissions) for photonics and optoelectronics.

Understanding the Stabilizing Effects of Nanoscale Metal Oxide and Li-Metal Oxide Coatings on Lithium-Ion Battery Positive Electrode Materials

Nickel-rich layered oxides, such as LiNi_0.6Co_0.2Mn_0.2O₂ (NMC622), are high-capacity electrode materials for lithium-ion batteries. However, this material faces issues, such as poor durability at high cut-off voltages (>4.4 V vs Li/Li⁺), which mainly originate from an unstable electrode-electrolyte interface. To reduce the side reactions at the interfacial zone and increase the structural stability of the NMC622 materials, nanoscale (<5 nm) coatings of TiO_x (TO) and Li_xTi_yO_z (LTO) were deposited over NMC622 composite electrodes using atomic layer deposition. It was found that these coatings provided a protective surface and also reinforced the electrode structure. Under high-voltage range (3.0-4.6 V) cycling, the coatings enhance the NMC electrochemical behavior, enabling longer cycle life and higher capacity. Cyclic voltammetry, X-ray photoelectron spectroscopy, and X-ray diffraction analyses of the coated NMC electrodes suggest that the enhanced electrochemical performance originates from reduced side reactions. In situ dilatometry analysis shows reversible volume change for NMC-LTO during the cycling. It revealed that the dilation behavior of the electrode, resulting in crack formation and consequent particle degradation, is significantly suppressed for the coated sample. The ability of the coatings to mitigate the electrode degradation mechanisms, illustrated in this report, provides insight into a method to enhance the performance of Ni-rich positive electrode materials under high-voltage ranges.

Giant anisotropic photonics in the 1D van der Waals semiconductor fibrous red phosphorus

A confined electronic system can host a wide variety of fascinating electronic, magnetic, valleytronic and photonic phenomena due to its reduced symmetry and quantum confinement effect. For the recently emerging one-dimensional van der Waals (1D vdW) materials with electrons confined in 1D sub-units, an enormous variety of intriguing physical properties and functionalities can be expected. Here, we demonstrate the coexistence of giant linear/nonlinear optical anisotropy and high emission yield in fibrous red phosphorus (FRP), an exotic 1D vdW semiconductor with quasi-flat bands and a sizeable bandgap in the visible spectral range. The degree of photoluminescence (third-order nonlinear) anisotropy can reach 90% (86%), comparable to the best performance achieved so far. Meanwhile, the photoluminescence (third-harmonic generation) intensity in 1D vdW FRP is strong, with quantum efficiency (third-order susceptibility) four (three) times larger than that in the most well-known 2D vdW materials (e.g., MoS2). The concurrent realization of large linear/nonlinear optical anisotropy and emission intensity in 1D vdW FRP paves the way towards transforming the landscape of technological innovations in photonics and optoelectronics.

Electronic and Magnetic Characterization of Epitaxial CrBr3 Monolayers on a Superconducting Substrate

The ability to imprint a given material property to another through a proximity effect in layered 2D materials has opened the way to the creation of designer materials. Here, molecular-beam epitaxy is used for direct synthesis of a superconductor-ferromagnet heterostructure by combining superconducting niobium diselenide (NbSe₂ ) with the monolayer ferromagnetic chromium tribromide (CrBr₃ ). Using different characterization techniques and density-functional theory calculations, it is confirmed that the CrBr₃ monolayer retains its ferromagnetic ordering with a magnetocrystalline anisotropy favoring an out-of-plane spin orientation. Low-temperature scanning tunneling microscopy measurements show a slight reduction of the superconducting gap of NbSe₂ and the formation of a vortex lattice on the CrBr₃ layer in experiments under an external magnetic field. The results contribute to the broader framework of exploiting proximity effects to realize novel phenomena in 2D heterostructures.

EXTERNAL DOSE RATE MONITORING IN FINLAND: HISTORY, EXPERIENCES AND A GLIMPSE AT THE FUTURE

Finland has a long history in monitoring external radiation. Regular monitoring began in the early 1960s when the first networks measuring exposure rates were established. Today the nation-wide network is fully automatic and consists of about 260 stations with Geiger-Műller (GM) tubes. Some 25 stations also have a LaBr3 spectrometer. In this article the authors describe the history, experiences and major development stages of the Finnish dose rate monitoring arrangements and also have a brief look at the possible future.

Titania nanotubes prepared by rapid breakdown anodization for photocatalytic decolorization of organic dyes under UV and natural solar light

Titania nanotube (TNT) powder was prepared by rapid breakdown anodization (RBA) in a perchloric acid electrolyte. The photocatalytic efficiency of the as-prepared and powders annealed at temperatures between 250 and 550 °C was tested under UV and natural sunlight irradiation by decolorization of both anionic and cationic organic dyes, i.e., methyl orange (MO) and rhodamine B (RhB), as model pollutants. The tubular structure of the nanotubes was retained up to 250 °C, while at 350 °C and above, the nanotubes transformed into nanorods and nanoparticles. Depending on the annealing temperature, the TNTs consist of anatase, mixed anatase/brookite, or anatase/rutile phases. The bandgap of the as-prepared nanotubes is 3.04 eV, and it shifts towards the visible light region upon annealing. The X-ray photoelectron spectroscopy (XPS) results show the presence of titania and impurities including chlorine on the surface of the TNTs. The atomic ratio of Ti/O remains unchanged for the annealed TNTs, but the concentration of chlorine decreases with temperature. The photoluminescence (PL) indicate high electron-hole recombination for the as-prepared TNTs, probably due to the residual impurities, low crystallinity, and vacancies in the structure, while the highest photocurrent was observed for the TNT sample annealed at 450 °C. The TNTs induce a small degradation of the dyes under UV light; however, contrary to previous reports, complete decolorization of dyes is observed under sunlight. All TNT samples showed higher decolorization rates under sunlight irradiation than under UV light. The highest reaction rate for the TNT samples was obtained for the as-prepared TNT powder sample under sunlight using RhB (κ₁ = 1.29 h^-1). This is attributed to the bandgap, specific surface area and the crystal structure of the nanotubes. The as-prepared TNTs performed most efficiently for decolorization of RhB and outperformed the reference anatase powder under sunlight irradiation. This could be attributed to the abundance of reactive sites, higher specific surface area, and degradation mechanism of RhB. These RBA TNT photocatalyst powders demonstrate a more efficient use of the sunlight spectrum, making them viable for environmental remediation.

Optimizing the sputter deposition process of polymers for the Storing Matter technique using PMMA

Quantitative analyses in secondary ion mass spectrometry (SIMS) become possible only if ionization processes are controlled. The Storing Matter technique has been developed to circumvent this so-called matrix effect, primarily for inorganic samples, but has also been extended to organic samples. For the latter, it has been applied to polystyrene in order to investigate the extent of damage in the polymer, its fragmentation during the sputter deposition process and the effect of the deposition process on the spectra taken by Time-of-Flight SIMS (ToF-SIMS). In this work, a multi-technique approach, which employs the Storing Matter technique for deposition and ToF-SIMS and X-ray photoelectron spectroscopy for characterization, is used to enhance the control of the deposition process, including the thickness of the deposit, the alteration of the source film and the influence of polymer composition on the Storing Matter process. Poly (methyl methacrylate) (PMMA) is used for this work. More detailed information about the sticking of polymer fragments on the metal collector is obtained by density functional theory calculations. This work allows for the conclusion that a part of the fragments deposited on the collector surface diffuses on the latter, reacts and recombines to form larger fragments. The behaviour observed for PMMA is similar to polystyrene, showing that oxygen has no major influence on the processes occurring during the sputter deposition process. Additionally, we have developed a new methodology using 2D ToF-SIMS images of the deposit to monitor the deposit thickness and to identify surface contaminations. The latter are not only located at the position of the deposit but all over the collector surface. Copyright © 2016 John Wiley & Sons, Ltd.

Does blood transfusion affect intermediate survival after coronary artery bypass surgery?

BACKGROUND

The aim of this study was to investigate the impact of transfusion of blood products on intermediate outcome after coronary artery bypass surgery.

PATIENTS

Complete data on perioperative blood transfusion in patients undergoing coronary artery bypass surgery were available from 2001 patients who were operated at our institution.

RESULTS

Transfusion of any blood product (relative risk = 1.678, 95% confidence interval = 1.087-2.590) was an independent predictor of all-cause mortality. The additive effect of each blood product on all-cause mortality (relative risk = 1.401, 95% confidence interval = 1.203-1.630) and cardiac mortality (relative risk = 1.553, 95% confidence interval = 1.273-1.895) was evident when the sum of each blood product was included in the regression models. However, when single blood products were included in the regression model, transfusion of fresh frozen plasma/Octaplas® was the only blood product associated with increased risk of all-cause mortality (relative risk = 1.692, 95% confidence interval = 1.222-2.344) and cardiac mortality (relative risk = 2.125, 95% confidence interval = 1.414-3.194). The effect of blood product transfusion was particularly evident during the first three postoperative months. Since follow-up was truncated at 3 months, transfusion of any blood product was a significant predictor of all-cause mortality (relative risk = 2.998, 95% confidence interval = 1.053-0.537). Analysis of patients who survived or had at least 3 months of potential follow-up showed that transfusion of any blood product was not associated with a significantly increased risk of intermediate all-cause mortality (relative risk = 1.430, 95% confidence interval = 0.880-2.323).

CONCLUSIONS

Transfusion of any blood product is associated with a significant risk of all-cause and cardiac mortality after coronary artery bypass surgery. Such a risk seems to be limited to the early postoperative period and diminishes later on. Among blood products, perioperative use of fresh frozen plasma or Octaplas seems to be the main determinant of mortality.

Experimental and numerical study of submonolayer sputter deposition of polystyrene fragments on silver for the storing matter technique

In static secondary ion mass spectrometry (SIMS), quantification and high ionization probabilities are difficult to obtain. The Storing Matter technique has been developed to circumvent these issues and has already been applied to deposit inorganic and organic samples. For organic samples, the effect of fragmentation during sputter deposition and changing coverage on time-of-flight (TOF)-SIMS mass spectra has not been investigated. In this work, polystyrene (PS) was sputter deposited on silver using an argon ion beam in order to investigate these parameters and to get a better control of the whole process. For this purpose, we introduce a multitechnique characterization approach for the submonolayer deposition of PS. Experimental methods (TOF-SIMS, X-ray photoelectron spectroscopy (XPS)) were used in combination with simulations (density functional theory (DFT) calculations) in order to obtain information about the molecular and structural changes and the interactions of organic matter with the metal surface. Alterations of the PS surface and PS sputter deposit as a function of surface coverage and Ar(+) ion fluence are addressed. A major finding is that this approach can be used to identify surface reactions between different fragments on the collector surface. Indeed, in the dynamic regime, the ratio of large to small fragments is increasing although the fragmentation during the sputter deposition should lead to increasingly smaller fragments. Hence, for Storing Matter, the coverage on the collector must be kept low in order to minimize the reactions between fragments and to preserve the information on the original sample.

Hybrid colloidal Au-CdSe pentapod heterostructures synthesis and their photocatalytic properties

In this report, we present a self-driven chemical process to design exclusive Au/CdSe pentapod heterostructures with Au core and CdSe arms. We have analyzed these heterostructures using high-resolution transmission electron microscope (HRTEM), high angle annular dark field-scanning transmission electron microscopic (HAADF-STEM), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) studies. Microscopic studies suggest that pentapod arms of CdSe are nucleated on the (111) facets of Au and linearly grown only along the [001] direction. From the XPS study, the shifting of peak positions in the higher binding energy region for Au/CdSe heterostructures compared to Au nanoparticles has been found which indicates the charge transfer from CdSe to Au in heterostructures. The steady state and time resolved spectroscopic studies unambiguously confirm the electron transfer from photoexcited CdSe to Au, and the rate of electron transfer is found to be 3.58×10⁸ s⁻¹. It is interesting to note that 87.2% of R6G dye is degraded by the Au/CdSe heterostructures after 150 min UV irradiation, and the apparent rate constant for Au/CdSe heterostructures is found to be 0.013 min⁻¹. This new class of metal-semiconductor heterostructures opens up new possibilities in photocatalytic, solar energy conversion, photovoltaic, and other new emerging applications.

Immediate and 5-year outcome after coronary artery bypass surgery in very high risk patients (additive EuroSCORE ≥ 10)

AIM

We have evaluated the outcome after coronary artery bypass surgery in very high risk patients (additive EuroSCORE ≥ 10). The impact of beating heart coronary artery bypass surgery (BHCAB) on their outcome has been evaluated.

METHODS

Retrospective study including 160 consecutive patients with additive EuroSCORE ≥ 10.

RESULTS

. The overall survival rates at 30-day, 1-year, 3-year and 5-year were 83.8%, 76.0%, 72.4% and 66.8%, respectively. Baseline cardiac index (O.R. 0.20, 95%C.I. 0.08-0.53), preoperative inotropic support (O.R. 4.55, 95%C.I. 1.41-14.73) and preoperative resuscitation (O.R. 3.937, 95%C.I. 1.02-15.26) were independent predictors of 30-day mortality. Baseline cardiac index (R.R. 0.48, 95%C.I. 0.28-0.85), left ventricular ejection fraction (P=0.032), preoperative use of intraaortic balloon pump (R.R. 3.22, 95% C.I. 1.50-6.93), preoperative tracheal intubation (R.R. 3.44, 95%C.I. 1.37-8.68) and creatinine (R.R. 1.004, 95%C.I. 1.00-1.01) were independent predictors of late death. OPCAB/BHCAB was associated with somewhat lower 30-day mortality rate (16.2% vs. 18.0%, P=0.73), stroke (2.0% vs. 4.9%, P=0.37), red blood cells transfusion (3.4 vs. 5.4 units, P=0.004) and combined adverse outcome (43.4% vs. 50.8%, P=0.42). OPCAB/BHCAB surgeons compared with surgeons with a prevalent conventional approach achieved slightly better the 30-day mortality rate (16.7% vs. 27.9%, P=0.15) and stroke rate (2.8% vs. 4.7%, P=0.60) and 5-year survival rate (65.3% vs. 57.4%, P=0.35).

CONCLUSION

Despite their poor immediate postoperative outcome, 5-year survival of these high risk patients is satisfactory and supports efforts in the treatment of this very high risk population. A more confident approach toward OPCAB/BHCAB is also suggested in these patients.

Deep pericardial sling versus lateral pericardial sutures in off-pump coronary artery bypass surgery

AIM

The aim of this study was to evaluate the safety and efficacy of deep pericardial sling (DPS) versus lateral pericardial sutures (LPSs) for heart stabilization and adequate coronary artery exposure during off-pump coronary artery bypass surgery (OPCAB).

METHODS

One surgeon employed in 101 consecutive patients a series of four to six 2-0 polyglactin sutures placed laterally between the left phrenic nerve and the left pulmonary veins (LPS). Two other surgeons used in 104 consecutive patients a single 0-0 braided silk suture with moistened gauze placed in the oblique sinus of the posterior pericardium, between the inferior vena cava and the right lower pulmonary vein (DPS).

RESULTS

One conversion to beating heart surgery with cardiopulmonary bypass support occurred in each study group. No patient in the LPS group was converted to DPS technique. The use of LPSs allowed a number of distal anastomoses somewhat higher than the DPS technique (4.1+/-1.1 vs. 3.7+/-1.1, P=0.02). Postoperative results were similar in both study groups. A lower incidence of postoperative low-cardiac output syndrome and of prolonged need of inotropes has been observed in the LPS group, but the difference failed to reach statistical significance. One patient in the LPS group had postoperative left phrenic nerve palsy. One patient in the DPS group suffered of intraoperative bleeding secondary to rupture of the inferior vena cava likely related to placement of DPS, which was successfully repaired.

CONCLUSION

LPS technique is as effective as DPS technique and allows complete revascularization with a postoperative outcome similar to the latter technique.

Risk of retinal microembolism after off-pump and on-pump coronary artery bypass surgery

AIM

In order to investigate the neuroprotective efficacy of off-pump coronary artery bypass surgery (OPCAB) over conventional on-pump coronary artery bypass surgery (CCAB), we have performed a prospective randomized study evaluating retinal circulation changes after OPCAB and CCAB.

METHODS

Twenty patients were randomized to OPCAB or CCAB. Retinal fluorescein angiography and 60 degrees black-and-white as well as color fundus photographs of both eyes of each patient were taken 1 to 24 h before and 5 to 6 days after the operation.

RESULTS

Patients undergoing OPCAB had more severely stenosed carotid arteries (P=0.075), higher incidence of slightly diseased ascending aorta (P=0.087) and higher Northern New England Cardiovascular Study Group stroke risk score (P=0.075). Neither stroke nor transient ischemic attack occurred postoperatively in these patients. Inferotemporal retinal arterial embolization and microinfarction was detected in one patient after CCAB, but in none of the OPCAB group.

CONCLUSION

The risk of retinal embolism can be minimized by the use of OPCAB and, most likely, by adequate epiaortic ultrasound scanning of the ascending aorta and avoiding clamping in case of severely diseased aorta.

Off-Pump versus On-Pump Coronary Artery Bypass Surgery in High-Risk Patients (EuroSCORE ≥ 6)

OBJECTIVE

The aim of this study was to review the results of off-pump (OPCAB) versus conventional on-pump coronary artery bypass surgery (CCAB) in high-risk patients.

METHODS

In a cohort of patients with an additive EuroSCORE >/= 6, 67 underwent OPCAB and 112 underwent CCAB.

RESULTS

Thirty-day postoperative death and stroke rates were 7.5 % and 6.0 % for the OPCAB group, and 5.4 % ( P = 0.75) and 8.0 % ( P = 0.77) for the CCAB group, respectively. No significant differences were observed for other major outcome endpoints other than cardiac troponin I (OPCAB: 117 +/- 428 ng/ml vs. CCAB: 58 +/- 99 ng/ml, P = 0.028), a result which was probably due to preoperative massive myocardial infarction in two very high-risk patients who underwent OPCAB. A similar outcome was also observed among propensity score-matched pairs. Congestive heart failure ( P = 0.006, OR: 6.366, 95 % CI: 1.682 - 24.093) and baseline cardiac index ( P = 0.018, OR: 0.171, 95 % CI: 0.040 - 0.735) were independent predictors of 30-day postoperative mortality.

CONCLUSIONS

OPCAB can be safely performed in high-risk patients with results as satisfactory as those achieved with CCAB.

Adhesion as an interplay between particle size and surface roughness

Surface roughness plays an important role in the adhesion of small particles. In this paper we have investigated adhesion as a geometrical effect taking into account both the particle size and the size of the surface features. Adhesion is studied using blunt model particles on surfaces up to 10 nm root-mean-square (RMS) roughness. Measurements with particles both smaller and larger than surface features are presented. Results indicate different behavior in these areas. Adhesion of particles smaller than or similar in size to the asperities depend mainly on the size and shape of the asperities and only weakly on the size of the particle. For large particles also the particle size has a significant effect on the adhesion. A new model, which takes the relative size of particles and asperities into account, is also derived and compared to the experimental data. The proposed model predicts adhesion well over a wide range of particle/asperity length scales.

Experimental humidity dependency of small particle adhesion on silica and titania

The humidity present in ambient atmosphere affects the adhesion of small particles by causing capillary bridge formation between the particle and the surface. Even in moderate relative humidities this, usually attractive, force can have a significant effect on adhesion behaviour of micro and sub-micro particles. We have directly measured the pull-off forces of initially adhered oxide particles on oxide surfaces with atomic force microscope in controlled atmosphere with adjustable humidity. We demonstrate the effect of the surface roughness resulting in two different regions of capillary formation and the particle shape having a strong effect on the humidity dependency of adhesion. The experimental results are explained by theoretical framework.

Radiation monitoring strategy: factors to be considered

In a nuclear or radiological emergency radiation measurements provide indispensable data needed in the management of the situation at hand. In order to assess the possible consequences correctly and to carry out proper countermeasures on time, the authorities must have a pre-prepared monitoring strategy at their disposal. There are, however, many different factors that affect a strategy. Thus, drawing up a comprehensive yet realistic emergency monitoring strategy is far from being an easy task. Some of the key factors related to strategies are reviewed and a simple way of producing a strategy plan is presented.

Microbiological quality and shelf-life of vacuum-packaged 'gravad' rainbow trout stored at 3 and 8 degrees C

Microbiological and sensory changes of vacuum-packaged 'gravad' rainbow trout slices were studied during storage at 3 and 8 degrees C. At the time of spoilage, after 27 and 20 days of storage at 3 and 8 degrees C, respectively, both mesophilic viable counts (MVC) and psychrotrophic viable counts (PVC) reached 10(6)-10(7) cfu/g at 3 degrees C and 10(7)-10(5) cfu/g at 8 degrees C. H2S-producing bacteria constituted a high proportion of the PVCs and lactic acid bacteria (LAB) counts were lower than the other determined bacterial counts. Sensory scores decreased with increasing MVC and PVC. The judges considered samples unfit for human consumption at MVC and PVC levels exceeding 10(6) and 10(7) cfu/g for samples stored at 3 and 8 degrees C, respectively. At respective levels of 10(7) and 10(8) cfu/g, most of the samples were deemed unfit. The main reasons for sensory rejection at both storage temperatures were the lack of the typical product odour or an ammonia off-odour and colour change to dark violet. The shelf-lives of the rainbow trout slices based on microbiological and sensory analyses were 20 days and 18 days at 3 and 8 degrees C, respectively.

Scaling of random spreading in small world networks

In this study we have carried out computer simulations of random walks on Watts-Strogatz-type small world networks and measured the mean number of visited sites and the return probabilities. These quantities were found to obey scaling behavior with intuitively reasoned exponents as long as the probability p of having a long range bond was sufficiently low.

Neuromuscular functioning of athletes and non-athletes in the drop jump

In many sports vertical jumping is important. This study compared neuromuscular functioning of the lower extremity muscles together with some kinetic and kinematic parameters before and during ground contact in drop jumps from two heights [0.4 m (DJ40) and 0.8 m (DJ80)] in 7 highly trained triple-jumpers and 11 physically active controls. The triple-jumpers jumped 32% higher in DJ40 and 34% higher in DJ80, had shorter braking and total contact times, and greater average and peak vertical ground reaction forces than the controls. In both drop jumps in the electromyogram pre-activity of the vastus lateralis and gastrocnemius muscles started earlier in the jumpers than in the controls. For the control group the increase in dropping height was associated with a decrease in the propulsion force, and resulted in more extended knee and ankle angles at touch down and more flexed angles at the deepest position than for the jumpers. All angular displacements for DJ80 were larger than for DJ40 in the control group. The triple jumpers and control subjects differed with respect to their neuromuscular functioning in the drop jump exercise and they responded in a different way to the increase in dropping height.

Computed tomographic evaluation of retrosternal adhesions after pericardial substitution

BACKGROUND

Reoperative median sternotomy can result in cardiac injury and serious bleeding, with the rate ranging from 2% to 6%. Closure of the native pericardium can maintain a preventing plane of cleavage. In patients in whom primary pericardial closure is not possible, several substitutes have been tried with variable results. We conducted a prospective study to evaluate the clinical feasibility of polytetrafluoroethylene and polyglycolic acid patches as pericardial substitutes, using computed tomography for imaging the postoperative state of the retrosternal space.

METHODS

The basic population comprised 540 patients who were scheduled for coronary artery bypass grafting, and 52 of them who met the research criteria were chosen for computed tomographic evaluation after 5 years after the primary operation.

RESULTS

As a substitute, polytetrafluoroethylene seemed to be less adhesive to the posterior surface of the sternum. Total adhesion scores were also statistically significant (p < 0.001) to the advantage of polytetrafluoroethylene over polyglycolic acid as a pericardial substitute.

CONCLUSIONS

Polytetrafluoroethylene membrane seems to be capable of minimizing retrosternal adhesion formation and thus it may protect the heart during subsequent reoperative sternotomy.

Pericardial closure with polytetrafluoroethylene surgical membrane or biodegradable polyglycolic acid mesh after coronary artery bypass surgery--a baseline report

BACKGROUND AND AIMS

Complete and tight closure of the native pericardium may kink or even occlude bypass grafts after coronary artery bypass grafting (CABG) and therefore the feasibility of tight closure has been debated. The growing number of reoperations has raised the question how to reduce the risk of damage of the right ventricle and patent grafts. We are performing a prospective randomized trial aiming to evaluate the feasibility of polytetrafluoroethylene (PTFE) surgical membrane and biodegradable polygycolic acid (PGA) mesh as pericardial substitutes for closure purposes in patients undergoing primary isolated CABG surgery.

MATERIAL AND METHODS

The series comprises 540 patients who underwent a primary isolated CABG procedure at the Oulu University Hospital from October 1989 to May 1994.

RESULTS AND CONCLUSIONS

The baseline results suggest that the PTFE and PGA materials seem to be similar despite the subtle early expression of tamponade related to the PTFE membrane after postoperative bleeding.

Options for the management of poststernotomy mediastinitis

The management of 27 consecutive deep sternotomy wound infections is reviewed. In 22 cases the initial treatment was debridement, sternal refixation and dilute antibiotic irrigation via multiple irrigation-suction catheters. In the nine cases (41%) in which these measures failed, more extensive sternal and costal cartilage debridement and closure with a muscle flap were performed. Five cases were initially managed with major reconstructive surgery. For reconstruction, a bilateral pectoralis major myocutaneous flap was used alone in eight cases, while in six the flap was insufficient to obliterate the whole poststernectomy space, and was supplemented with rectus abdominis muscle. Early mediastinitis can be effectively treated with thorough wound debridement and mediastinal irrigation, but if there is a two-week delay from the initial sternotomy to manifestation of infection, radical debridement with muscle flap closure should be seriously considered.

Surgical and long-term outcome of graft replacement of aneurysms of the descending thoracic aorta. Analysis of 28 consecutive cases

A consecutive series of 28 patients operated on at the Oulu University Hospital during the years 1974-1994 for aneurysms of the descending thoracic aorta is presented. Twenty-five cases were elective and three were operated on as emergencies. Their mean age was 58 years. During the aortic cross-clamp, circulatory support of the lower body, was used in 27 cases as follows: a direct aorto-femoral shunt without a pump (12/28), left-heart bypass (11/28) or femoro-femoral perfusion (4/28). Hospital mortality was 14% (4/28). One patient with a ruptured aneurysm died of renal failure, but there were no other renal complications. None had paraplegia postoperatively. Three had symptoms of paraparesis, but only one of them had a slight permanent discomfort while walking. The mean follow-up time was 100 months, range 2-242 months. Late actuarial survival including hospital mortality, was 65% at 5 years and 41% at 10 years, reflecting the generalized aortic disease with a high risk of very late rupture (4) and other manifestations of atherosclerosis with myocardial infarction (6) or cerebral atherosclerosis (1), the remaining late deaths being unrelated. The efficacy of lower body circulatory support in avoiding peroperative renal and spinal cord ischaemic complications is demonstrated.