A Sustainable Method for Removal of the Full Range of Liquid and Solid Hydrocarbons from Water Including Up- and Recycling

Beyond their CO2 emittance when burned as fuels, hydrocarbons (HCs) serve as omnipresent raw materials and commodities. No matter if as liquid oil spills or the endless amounts of plastic roaming the oceans, HCs behave as persistent pollutants with water as main carrier to distribute. Even if their general chemical structure [-(CH2 )n -] is quite simple, the endless range of n leads to contaminations of different appearances and properties. A water remediation method based on superparamagnetic iron oxide nanoparticles (SPIONs) modified with self-assembled monolayers of alkyl phosphonic acid derivatives is presented. These molecules enable the SPIONs to non-covalently bind HCs, independently from the molecular weight, size and morphology. The attractive interaction is mainly based on hydrophobic and Coulomb interaction, which allows recycling of the SPIONs. The superparamagnetic core allows a simple magnetic collection and separation from the water phase which makes it a promising addition to wastewater treatment. Agglomerates of collected plastic "waste" even exhibit superior adsorption properties for crude oil, another hydrocarbon waste which gives these collected wastes a second life. This upcycling approach combined with presented recycling methods enables a complete recycling loop.

AgIn5S8/ZnS Quantum Dots for Luminescent Down-Shifting and Antireflective Layer in Enhancing Photovoltaic Performance

Colloidal AgIn5S8/ZnS quantum dots (QDs) have recently emerged as a promising, efficient, nontoxic, down-shifting material in optoelectronic devices. These QDs exhibit a high photoluminescent quantum yield and offer a range of potential applications, specifically in the field of photovoltaics (PVs) for light management. In this work, we report an eco-friendly method to synthesize AgIn5S8/ZnS QDs and deposit them on commercial silicon solar cells (with an active area of 7.5 cm2), with which the short-circuit current (JSC) enhanced by 1.44% and hence the power conversion efficiency by 2.51%. The enhancements in PV performance are mainly attributable to the improved external quantum efficiency in the ultraviolet region and reduced surface reflectance in the ultraviolet and near-infrared regions. We study the effect of QD concentration on the bifunctions of downshifting and antireflection. The optimal 15 mg/mL QDs blade-coated onto the Si solar cells realize maximum current generation as the reflectance loss in the visible wavelength is compensated by the minimized reflection in the near-infrared region.

Polythiophene as a Double-Electrostatic Template for Zinc Oxide and Gold: Multicomponent Nano-Objects for Enhanced Photocatalysis

Using electrostatic self-assembly and electrostatic nanotemplating, a quaternary nanostructured system consisting of zinc oxide nanoparticles, gold nanoparticles, poly[3-(potassium-4-butanoate)thiophene-2,5-diyl] (PT), and methyltrioctylammonium chloride (MTOA) (PT-MTOA-ZnO-Au) was designed for aqueous photocatalysis. The PT-MTOA hollow sphere aggregates served as an electrostatic template for both individual inorganic nanoparticles controlling their morphology, stabilizing the nanoparticles, and acting as a photosensitizer. The hybrid structures included spherical ZnO nanoparticles with a diameter of d = 2.6 nm and spherical Au nanoparticles with d = 6.0 nm embedded in PT-MTOA hollow spheres with a hydrodynamic radius of R_H = 100 nm. The ZnO nanoparticles acted as the main catalyst, while the Au nanoparticles acted as the cocatalyst. As a photocatalytic model reaction, the dye degradation of methylene blue in aqueous solution using the full spectral range from UV to visible light was tested. The photocatalytic activity was optimized by varying the Zn and Au loading ratios and was substantially enhanced regarding the components; for example, it was increased by about 61% using PT-MTOA-ZnO-Au compared to the composite without gold particles. A photocatalytic mechanism of the methylene blue degradation was proposed when catalyzed by these multicomponent nano-objects. Thus, a simple procedure of templating two different nanoparticle species within the same cocatalytically active template has been demonstrated, which can be extended to other inorganic particles, making a variety of task-specific catalysts accessible.

Light-Induced Agglomeration of Single-Atom Platinum in Photocatalysis

With recent advances in the field of single-atoms (SAs) used in photocatalysis, an unprecedented performance of atomically dispersed co-catalysts has been achieved. However, the stability and agglomeration of SA co-catalysts on the semiconductor surface may represent a critical issue in potential applications. Here, the photoinduced destabilization of Pt SAs on the benchmark photocatalyst, TiO₂ , is described. In aqueous solutions within illumination timescales ranging from few minutes to several hours, light-induced agglomeration of Pt SAs to ensembles (dimers, multimers) and finally nanoparticles takes place. The kinetics critically depends on the presence of sacrificial hole scavengers and the used light intensity. Density-functional theory calculations attribute the light induced destabilization of the SA Pt species to binding of surface-coordinated Pt with solution-hydrogen (adsorbed H atoms), which consequently weakens the Pt SA bonding to the TiO₂ surface. Despite the gradual aggregation of Pt SAs into surface clusters and their overall reduction to metallic state, which involves >90% of Pt SAs, the overall photocatalytic H₂ evolution remains virtually unaffected.

Regioselective Seeded Polymerization in Block Copolymer Nanoparticles: Post‐Assembly Control of Colloidal Features

Post‐assembly modifications are efficient tools to adjust colloidal features of block copolymer (BCP) particles. However, existing methods often address particle shape, morphology, and chemical functionality individually. For simultaneous control, we transferred the concept of seeded polymerization to phase separated BCP particles. Key to our approach is the regioselective polymerization of (functional) monomers inside specific BCP domains. This was demonstrated in striped PS‐b‐P2VP ellipsoids. Here, polymerization of styrene preferably occurs in PS domains and increases PS lamellar thickness up to 5‐fold. The resulting asymmetric lamellar morphology also changes the particle shape, i.e., increases the aspect ratio. Using 4‐vinylbenzyl azide as co‐monomer, azides as chemical functionalities can be added selectively to the PS domains. Overall, our simple and versatile method gives access to various multifunctional BCP colloids from a single batch of pre‐formed particles.

Additive Manufacturing in Atomic Layer Processing Mode

Additive manufacturing (3D printing) has not been applicable to micro- and nanoscale engineering due to the limited resolution. Atomic layer deposition (ALD) is a technique for coating large areas with atomic thickness resolution based on tailored surface chemical reactions. Thus, combining the principles of additive manufacturing with ALD could open up a completely new field of manufacturing. Indeed, it is shown that a spatially localized delivery of ALD precursors can generate materials patterns. In this "atomic-layer additive manufacturing" (ALAM), the vertical resolution of the solid structure deposited is about 0.1 nm, whereas the lateral resolution is defined by the microfluidic gas delivery. The ALAM principle is demonstrated by generating lines and patterns of pure, crystalline TiO₂ and Pt on planar substrates and conformal coatings of 3D nanostructures. The functional quality of ALAM patterns is exemplified with temperature sensors, which achieve a performance similar to the industry standard. This general method of multimaterial direct patterning is much simpler than standard multistep lithographic microfabrication. It offers process flexibility, saves processing time, investment, materials, waste, and energy. It is envisioned that together with etching, doping, and cleaning performed in a similar local manner, ALAM will create the "atomic-layer advanced manufacturing" family of techniques.

Noncovalent Liquid Phase Functionalization of 2H-WS2 with PDI: An Energy Conversion Platform with Long-Lived Charge Separation

Transition metal dichalcogenides are attractive 2D materials in the context of solar energy conversion. Previous investigations have focused predominantly on the properties of these systems. The realization of noncovalent hybrids with, for example, complementary electroactive materials remains underexplored to this date for exfoliated WS₂. In this contribution, we explore WS₂ by means of exfoliation and integration together with visible light-absorbing and electron-accepting perylene diimides into versatile electron-donor acceptor hybrids. Important is the distinct electron-donating feature of WS₂. Detailed spectroscopic investigations of WS₂–PDI confirm the electron donor/acceptor nature of the hybrid and indicate that green light photoexcitation leads to the formation of long-lived WS₂^•+–PDI^•– charge-separated states.

Distinct endocytosis and immune activation of poly(lactic-co-glycolic) acid nanoparticles prepared by single- and double-emulsion evaporation

Background: Poly(lactic-co-glycolic) acid (PLGA) nanoparticles can be prepared by emulsion-solvent-evaporation from o/w and w₁/o/w₂ emulsions. Aims: To elaborate similarities and differences regarding mechanical, morphological and physicochemical properties, as well as endocytosis and dose-dependent immune responses by primary human leukocytes between nanoparticles prepared by these two methods. Methods: Fluorescently labeled as well as TLR agonist (R848)-loaded PLGA nanoparticles were prepared via both single- and double-emulsion solvent evaporation. Results: Particles prepared by both methods were similar in chemical composition and surface charge but exhibited slight differences in size and morphology. Pronounced differences were found for loading, dissolution and mechanical properties. The particles were differently endocytosed by monocytes and induced qualitatively and quantitatively different immune responses. Conclusions: Variations in nanoparticle preparation can affect particle-derived immunological characteristics.

As a single atom Pd outperforms Pt as the most active co-catalyst for photocatalytic H2 evolution

Here, we evaluate three different noble metal co-catalysts (Pd, Pt, and Au) that are present as single atoms (SAs) on the classic benchmark photocatalyst, TiO₂. To trap the single atoms on the surface, we introduced controlled surface vacancies (Ti³⁺-O_v) on anatase TiO₂ nanosheets by a thermal reduction treatment. After anchoring identical loadings of single atoms of Pd, Pt, and Au, we measure the photocatalytic H₂ generation rate and compare it to the classic nanoparticle co-catalysts on the nanosheets. While nanoparticles yield the well-established the hydrogen evolution reaction activity sequence (Pt > Pd > Au), for the single atom form, Pd radically outperforms Pt and Au. Based on density functional theory (DFT), we ascribe this unusual photocatalytic co-catalyst sequence to the nature of the charge localization on the noble metal SAs embedded in the TiO₂ surface.

ZnS Ultrathin Interfacial Layers for Optimizing Carrier Management in Sb2S3-based Photovoltaics

Antimony chalcogenides represent a family of materials of low toxicity and relative abundance, with a high potential for future sustainable solar energy conversion technology. However, solar cells based on antimony chalcogenides present open-circuit voltage losses that limit their efficiencies. These losses are attributed to several recombination mechanisms, with interfacial recombination being considered as one of the dominant processes. In this work, we exploit atomic layer deposition (ALD) to grow a series of ultrathin ZnS interfacial layers at the TiO2/Sb2S3 interface to mitigate interfacial recombination and to increase the carrier lifetime. ALD allows for very accurate control over the ZnS interlayer thickness on the ångström scale (0-1.5 nm) and to deposit highly pure Sb2S3. Our systematic study of the photovoltaic and optoelectronic properties of these devices by impedance spectroscopy and transient absorption concludes that the optimum ZnS interlayer thickness of 1.0 nm achieves the best balance between the beneficial effect of an increased recombination resistance at the interface and the deleterious barrier behavior of the wide-bandgap semiconductor ZnS. This optimization allows us to reach an overall power conversion efficiency of 5.09% in planar configuration.

LPE growth of Tb3Al5O12:Ce single crystalline film converters for WLED application

Efficient phosphor converters for white LEDs based on TbAG:Ce single crystalline films, LPE grown onto YAG substrates, is developed. The film-substrate interface of TbAG:Ce SCF/YAG epitaxial structures was studied using high-resolution STEM images.

Topological Kagome Magnet Co3Sn2S2 Thin Flakes with High Electron Mobility and Large Anomalous Hall Effect

Magnetic Weyl semimetals attract considerable interest not only for their topological quantum phenomena but also as an emerging materials class for realizing quantum anomalous Hall effect in the two-dimensional limit. A shandite compound Co₃Sn₂S₂ with layered kagome-lattices is one such material, where vigorous efforts have been devoted to synthesize the two-dimensional crystal. Here, we report a synthesis of Co₃Sn₂S₂ thin flakes with a thickness of 250 nm by chemical vapor transport method. We find that this facile bottom-up approach allows the formation of large-sized Co₃Sn₂S₂ thin flakes of high-quality, where we identify the largest electron mobility (∼2600 cm² V^-1 s^-1) among magnetic topological semimetals, as well as the large anomalous Hall conductivity (∼1400 Ω^-1 cm^-1) and anomalous Hall angle (∼32%) arising from the Berry curvature. Our study provides a viable platform for studying high-quality thin flakes of magnetic Weyl semimetal and stimulate further research on unexplored topological phenomena in the two-dimensional limit.

Long‐Living Holes in Grey Anatase TiO2 Enable Noble‐Metal‐Free and Sacrificial‐Agent‐Free Water Splitting

Titanium dioxide has been the benchmark semiconductor in photocatalysis for more than 40 years. Full water splitting, that is, decomposing water into H₂ and O₂ in stoichiometric amounts and with an acceptable activity, still remains a challenge, even when TiO₂‐based photocatalysts are used in combination with noble‐metal co‐catalysts. The bottleneck of anatase‐type TiO₂ remains the water oxidation, that is, the hole transfer reaction from pristine anatase to the aqueous environment. In this work, we report that “grey” (defect engineered) anatase can provide a drastically enhanced lifetime of photogenerated holes, which, in turn, enables an efficient oxidation reaction of water to peroxide via a two‐electron pathway. As a result, a Ni@grey anatase TiO₂ catalyst can be constructed with an impressive performance in terms of photocatalytic splitting of neutral water into H₂ and a stoichiometric amount of H₂O₂ without the need of any noble metals or sacrificial agents. The finding of long hole lifetimes in grey anatase opens up a wide spectrum of further photocatalytic applications of this material.

Interaction of Np(v) with borate in alkaline, dilute-to-concentrated, NaCl and MgCl2 solutions

The formation of sparingly soluble ternary Na/Mg–Np(v)–borate(s) solid phases in alkaline, dilute-to-concentrated, NaCl and MgCl₂ solutions is confirmed by a multimethod experimental approach.

Fate of Lu(III) sorbed on 2-line ferrihydrite at pH 5.7 and aged for 12 years at room temperature. II: insights from STEM-EDXS and DFT calculations

Transformation products of two-line ferrihydrite associated with Lu(III) were studied after 12 years of aging using aberration-corrected high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), high-efficiency energy-dispersive X-ray spectroscopy (EDXS), and density functional theory (DFT). The transformation products consisted of hematite nanoparticles with overgrown goethite needles. High-efficiency STEM-EDXS revealed that Lu is only associated with goethite needles, and atomic-resolution HAADF-STEM reveals structural incorporation of Lu within goethite, partially replacing structural Fe sites. This finding corroborates those recently obtained by AsFlFFF and EXAFS spectroscopy on the same sample (Finck et al. 2018). DFT calculations indicate that Lu incorporation within goethite or hematite are almost equally likely, suggesting that experimental parameters such as temperature and reaction time which affect reaction kinetics, play important roles in determining the Lu uptake. It seems likely that these results may be transferable to predict the behavior of chemically homologous trivalent actinides.

Intrinsically Activated SrTiO3: Photocatalytic H2 Evolution from Neutral Aqueous Methanol Solution in the Absence of Any Noble Metal Cocatalyst

Noble metal cocatalysts are conventionally a crucial factor in oxide-semiconductor-based photocatalytic hydrogen generation. In the present work, we show that optimized high-temperature hydrogenation of commercially available strontium titanate (SrTiO₃) powder can be used to engineer an intrinsic cocatalytic shell around nanoparticles that can create a photocatalyst that is highly effective without the use of any additional cocatalyst for hydrogen generation from neutral aqueous methanol solutions. This intrinsic activation effect can also be observed for SrTiO₃[100] single crystal as well as Nb-doped SrTiO₃[100] single crystal. For all types of SrTiO₃ samples (nanopowders and either of the single crystals), hydrogenation under optimum conditions leads to a surface-hydroxylated layer together with lattice defects visible by transmission electron microscopy, electron paramagnetic resonance (EPR), and photoluminescence (PL). Active samples provide specific defects identified by EPR, PL, and electron-energy loss spectroscopy as Ti³⁺ states in a defective matrix-this is in contrast to the inactive defects formed in other reductive atmospheres. In aqueous media, active SrTiO₃ samples show a significant negative shift of the flatband potential (in photoelectrochemical as well as in capacitance data) and a lower charge-transfer resistance for photoexcited electrons. We therefore ascribe the remarkable cocatalyst-free activation of the material to a synergy between thermodynamics (altered interface energetics induced by hydroxylation) and kinetics (charge transfer mediation by suitable Ti³⁺ states).

Exploring the electronic structure and speciation of aqueous and colloidal Pu with high energy resolution XANES and computations

Pu L₃ HR-XANES fingerprints loss of inversion symmetry: rising pre-edge (d,e), shorter A–B distance (d,e), split Pu d-DOS (e).

Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles

Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M₄ high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U(IV), U(V), and U(VI) existing simultaneously in the same sample. The contributions of the three different uranium redox states are quantified with the iterative transformation factor analysis (ITFA) method. U L₃ XAS and transmission electron microscopy (TEM) reveal that initially sorbed U(VI) species recrystallize to nonstoichiometric UO_2+x nanoparticles within 147 days when stored under anoxic conditions. These U(IV) species oxidize again when exposed to air. U M₄ HR-XANES data demonstrate strong contribution of U(V) at day 10 and that U(V) remains stable over 142 days under ambient conditions as shown for magnetite nanoparticles containing 1000 ppm U. U L₃ XAS indicates that this U(V) species is protected from oxidation likely incorporated into octahedral magnetite sites. XAS results are supported by density functional theory (DFT) calculations. Further characterization of the samples include powder X-ray diffraction (pXRD), scanning electron microscopy (SEM) and Fe 2p X-ray photoelectron spectroscopy (XPS).

Microscopic structures of Laves phases and structurally related compounds: a transmission electron microscopy study

We present microstructural investigations of Laves phases AB2 and structurally related compounds using transmission electron microscopy. Convergent-beam electron diffration in combination with selected-area diffraction has been used to determine uniquely the space group symmetry of the respective phases from very small illuminated regions. In addition stacking faults, domain boundaries, and intergrowth have been studied by HREM images. By electron beam irradiation intermetallic phases have been transformed in-situ into phases of different compositions. Polar intermetallic phases in the systems Ca—Al—Zn, Ba—Al and Ba—Al—Zn, as well as transition metal based Nb-Co phases have been chosen for this case study. In the Ca—Al—Zn system, the C15- and C36-type crystals did not show orderliness but a randomly mixed occupation of the B-net by Al and Zn atoms. Starting from C36, a C15 phase of constant Ca and lower Zn content as well as a new C36 phase with higher Ca content could be synthesized by means of electron beam irradiation. In the case of CaAlZn no ordering of Al and Zn were observed, i.e., Al and Zn randomly mixed occupy the Cu-site in the CeCu2 structure type. By electron beam irradiation of CaAlZn, a novel hexagonal phase with a hitherto unknown crystal structure is formed. The crystal structures of Ba21Al40 and Ba14Al22+xZn5–x are derived from Laves-type structures by omitting and modifying some of the triangular and Kagom, layers. In the case of Ba21Al40, intergrowth of motifs from the crystal structures of Ba3Al5 and Ba4Al5 were observed, whereas for Ba14Al22+xZn5–x the bulk phase displays a domain structure. Adjacent domains are misoriented by ∼120°, the specific angle resulting from the pseudo-trigonal symmetry of the Ba-net. Therefore, only the (Al,Zn)-net is disordered. No superstructure formation were detected for the three polytypes C36, C15 and C14 in the Nb—Co system. However, TEM images of C36-Nb1–xCo2+x reveal a high stacking fault density with intergrowth of stacks of C36 and C15 sequence. When the C15 phase is rich in Nb, stacking faults seem to be more important than for Co-rich C15 phases, whereas stacking faults have seldom been observed for the Co-rich C14 phase.

Origin of the Monoclinic-to-Monoclinic Phase Transition and Evidence for the Centrosymmetric Crystal Structure of BiMnO3

Structural properties of polycrystalline single-phased BiMnO3 samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO3 crystallizes in the centrosymmetric space group C2/c at 300 K. The crystallographic data are a = 9.5415(2) A, b = 5.61263(8) A, c = 9.8632(2) A, beta = 110.6584(12) degrees at 300 K and a = 9.5866(3) A, b = 5.59903(15) A, c = 9.7427(3) A, beta = 108.601(2) degrees at 550 K, Z = 8, space group C2/c. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO3 at 300 K melts above TOO = 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature, mueff = 4.69 microB and theta = 138.0 K at 300-450 K and mueff = 4.79 microB and theta = 132.6 K at 480-600 K.

Phase Stability in the Systems AeAl2-xMgx (Ae = Ca, Sr, Ba): Electron Concentration and Size Controlled Variations on the Laves Phase Structural Theme

The systems AeAl(2-x)Mgx (Ae = Ca, Sr, Ba) display electron concentration induced Laves phase structural changes. However, the complete sequence MgCu2 --> MgNi2 --> MgZn2 with increasing x (decreasing electron count) is only observed for Ae = Ca. Compounds SrAl(2-x)Mgx (0 < x < or = 2) and BaAl(2-x)Mgx (x = 0.85 and 2.0) were synthesized and structurally characterized by X-ray diffraction experiments. For the Sr system the structural sequence CeCu2 --> MgNi2 --> MgZn2 occurs with increasing Mg content x. Thus, larger Sr does not allow the realization of the MgCu2 structure at low x. For Ae = Ba a binary compound BaAl2 does not exist, but more Ba-rich Ba7Al13 forms. The reinvestigation of the crystal structure of Ba7Al13 by selected area and convergent beam electron diffraction in a transmission electron microscope revealed a superstructure, which subsequently could be refined from single X-ray diffraction data. The formula unit of the superstructure is Ba21Al40 (space group P31m, Z = 1, a = 10.568(1) angstroms, c = 17.205(6) angstroms). In Ba21Al40 a size match problem between Ba and Al present in Ba7Al13 is resolved. The structure of Ba7Al13 (Ba21Al40) can be considered as a Ba excess variant of the hexagonal MgNi2 Laves phase type structure. An incommensurately modulated variant of the MgNi2 structure is obtained for phases BaAl(2-x)Mgx with x = 0.8-1. At even higher Mg concentrations a structural change to the proper MgZn2 type structure takes place.

Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors: RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212)

Microstructures of the RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212) magneto-superconductors have been investigated by using selected-area electron diffraction, convergent-beam electron diffraction, dark-field electron microscopy and high-resolution electron microscopy at room temperature. Both Ru-1212 and Ru-1222 consist of nm-size domains stacked along the [Formula: see text] direction, where the domains are formed by two types of superstructures due to ordering of rotated RuO(6) octahedra about the c-axis. In Ru-1212, both primitive-and body-centered tetragonal superstructures (the possible space groups: P4/mbm and I4/mcm) are derived to form the corresponding nm-domains. It is of great interest that Ru-1212 consists of domains of two crystallographically different superstructures, while the similar domains observed in Ru-1222 have crystallographically identical superstructure with an orthorhombic symmetry (possible space group: Aeam), related by 90 degrees rotation around the c-axis (Yokosawa et al., 2003, submitted for publication).

Treatment of mediastinitis arising after replacement of the ascending aorta

Mediastinitis due to graft infection is a serious and potentially lethal complication associated with replacement of the ascending aorta. We present the case of a 67-year-old man with this condition for the aneurysm and chronic dissection. Mediastinitis and sepsis were diagnosed and debridement, irrigation with povidone solution and omental transposition were performed successfully. Continuous closed irrigation prior to omental transposition without replacement of the infected graft is useful for treating mediastinitis after ascending aortic or arch replacement.

[A case of quadricuspid aortic valve associated with mitral regurgitation]

A case of a 60-year-old man associated with quadricuspid aortic valve and mitral regurgitation is reported. The aortic valve consisted of three larger cusps and a small accessory cusp situated between the right and the non-coronary cusps. The aortic regurgitation resulted from malcoaptation of the four cusps and the mitral regurgitation resulted from annulus dilatation and thickening of the anterior leaflet. The surgical treatment was performed successfully by the aortic and mitral valve replacements with St. Jude Medical valves. The patient is doing well fifteen months postoperatively. Sixteen Japanese cases of quadricuspid aortic valve which were corrected surgically are reviewed.

[A case who developed mechanical pulsus alternans after Bentall's operation for annuloaortic ectasia]

Left ventricular pulsus alternans developed immediately after Bentall's operation in a 37-year-old patient with Marfan's syndrome accompanied by severe left heart failure due to annuloaortic ectasia. Echocardiographic examination suggested that this symptom was caused by alternating contractility based on left ventricular myocardial failure. Left heart failure disappeared early after operation, but pulsus alternans persisted until 7 months after operation, when EDVI decreased from 225 ml/m2 to 113 ml/m2.

[Successful repair of an acute type A dissection during pregnancy]

We report a successful repair of an acute type-A aortic dissection during pregnancy. A 29-year-old pregnant woman in the 32 weeks of gestation with Marfan Syndrome was admitted to our hospital for the treatment of anterior chest and back pains. An urgent aortogram through pulmonary artery revealed an aortic dissection beginning from the ascending aorta to the aortic bifurcation. On the following day, an emergent Cesarean section was performed and a baby weighing 1944 g was delivered. Thereafter, cardiopulmonary bypass was instituted and the ascending aorta was opened. An intimal tear was found 2 cm above the aortic valve. The dissected space was closed with reinforcement of Teflon felt strip. A Dacron gusset was sutured to restore aortic continuity. During the weaning from the CPB, a retrograde aortic dissection developed and the heart became arrested. Therefore we immediately converted the aortic perfusion cannula from the right external iliac artery to graft of the ascending aorta, and the operation was completed successfully with a good recovery of the heart. The mother and her child have been alive and well for 3 years and 5 months after the operation.

[Subdural hematoma following surgery of an aneurysm of the diverticulum of the ductus arteriosus with partial cardiopulmonary bypass]

The patient was a 72-year-old man, who had an aneurysm of the descending thoracic aorta with left recurrent laryngeal nerve palsy identified by preoperative examination. Thoracotomy revealed an aneurysm of a diverticulum of the ductus arteriosus measuring 2.7 X 3.4 cm. The aneurysm was excised under partial cardiopulmonary bypass and the defect of the aortic wall was repaired with a Dacron patch. Two days after surgery, he developed mild deterioration of consciousness and right hemiparesis. An acute subdural hematoma which covered the left frontal, parietal, and temporal lobes was found by CT examination. Craniotomy was performed 16 days after the previous surgery, and 100 g of hematoma was removed. Following craniotomy, complete recovery of cerebral function was observed. This appears to be a valuable report of a patient who developed acute subdural hematoma following surgery of aneurysms of the descending thoracic aorta with partial cardiopulmonary bypass.

[Successful mitral valve replacement for infective endocarditis in pregnancy]

A 27 weeks' pregnant women exhibited infective endocarditis due to alpha-streptococcus. As echocardiography showed vegetations on both mitral leaflets, cesarean section was performed at 35 weeks' gestation and a healthy male infant weighing 2,430 g was delivered. Antibiotic therapy was continued for fever after the cesarean section but macrohematuria and Osler's nodes developed. Emergency mitral valve replacement was performed successfully despite the presence of active infective endocarditis. She was discharged after completion of a 10-week course of antibiotic therapy.

[Effects of cardioplegic solutions on coronary artery and myocardium--comparison of the glucose-insulin-potassium solution and the St. Thomas' Hospital cardioplegic solution]

Effects of two cardioplegic solutions on coronary artery and myocardium were experimentally investigated in three types of preparations. In the isolated perfused guinea pig heart, infusion of Glucose-Insulin-Potassium (GIK) solution (37 degrees C) caused contraction of coronary artery, whereas the St. Thomas' Hospital cardioplegic solution (37 degrees C) produced vasodilation. At the end of 30 minutes reperfusion after continuous infusion of cardioplegic solution, the St. Thomas' Hospital cardioplegic solution produced a greater recovery of cardiac function than GIK solution. In the isolated pig coronary artery, vasoconstriction caused by high potassium content was diminished by addition of magnesium in concentration dependent manner. In the electrophysiological examination, the membrane potential of the guinea pig papillary muscle was recorded by means of conventional glass microelectrodes. Though GIK solution produced greater depolarization of resting membrane potential than the St. Thomas' Hospital cardioplegic solution, effects of the two different cardioplegic solution was not so different after reperfusion of Tyrode solution. The St. Thomas' Hospital cardioplegic solution resulted in greater recovery of contracting activity after reperfusion than GIK solution. These data suggest that GIK solution causes coronary vasoconstriction and has deleterious effects on myocardium and that the St. Thomas' Hospital cardioplegic solution has a vasodilating action and produced a greater myocardial protection than GIK solution.

Functional and metabolic protection of the neonatal myocardium from ischemia. Insufficient protection by cardioplegia

The effects of ischemia and cardiac arrest by cardioplegia on the mechanical function and energy metabolism of the ventricular myocardium of the neonatal guinea pig were investigated in the isolated perfused heart preparation and compared with these effects in the adult guinea pig. Whereas reperfusion after ischemia resulted in better recovery of mechanical function and a higher adenosine triphosphase content in the neonatal myocardium than in the adult, recovery from cardiac arrest induced by St. Thomas' Hospital cardioplegic solution was not as good in the neonatal myocardium as in the adult. Contracture developed in the neonatal myocardium on administration of the cardioplegic solution, but did not in the adult. This was considered to be the reason that the protective effect of the cardioplegic solution was inferior in the neonatal myocardium to that in the adult.

Difference in the mechanical response to a cardioplegic solution observed between the neonatal and the adult guinea pig myocardium

We attempted in two types of preparations to delinate the difference in responses to St. Thomas' Hospital cardioplegic solution between the neonatal and the adult guinea pig myocardium. Isolated guinea pig hearts were perfused with Langendorff's method and the tension of the papillary muscle of the right ventricle was recorded. Continuous infusion of St. Thomas' Hospital cardioplegic solution (37 degrees C) for 30 minutes resulted in a significantly higher elevation of the resting tension (development of contracture) in the neonatal myocardium than in the adult. The recovery of normal contractile tension after the resumption of perfusion with normal Krebs-Ringer bicarbonate solution was smaller in the neonate with increases in the myocardial water and calcium contents. The membrane potential of the papillary muscle preparation was recorded by means of conventional glass microelectrodes. There was no significant difference in the control values of the resting membrane potential and in the degree of depolarization during exposure to St. Thomas' Hospital cardioplegic solution between the neonate and the adult. Thus the greater elevation of the resting tension produced in the neonatal myocardium by St. Thomas' Hospital cardioplegic solution was not due to a greater depolarization of the surface membrane.

Successful resection of cardiac fibroma with ventricular tachycardia

A 22-year-old male was admitted to Niigata University Hospital complaining of palpitation. Echocardiogram, cineangiogram, and Holter electrocardiogram revealed a cardiac fibroma complicated by ventricular tachycardia (VT). The tumor extended from the interventricular septum to the anterior surface of the left ventricle, and an electrophysiological study demonstrated that the focus of the VT was situated at the tumor. The tumor was excised successfully. The patient is doing well two years after operation without any antiarrhythmic drugs, and VT has not recurred.