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Detailed knowledge about the relationship between the electronic structure and the catalytic properties of a material is a fundamental brick to rationally design better oxygen evolution reaction (OER) catalysts. Here, resonant photoelectron spectroscopy (RPES) is used to elucidate the electronic structure and active state of the most broadly employed OER catalyst, Ni-Fe (oxy)hydroxides. We implemented a graphene-capped catalyst-coated ionomer membrane approach. Starting from a well-characterized iron nickel oxide precursor, the changes in the electronic structure of oxygen and nickel species with different applied electrode potentials were studied. In particular, RPES measurements helped to distinguish between formal Ni3+ and Ni4+ species emerging upon catalyst oxidation, which indicate charge accumulation in adjacent hole states. Based on RPES, the core-level binding energy and partial electron yield absorption spectroscopy (PEY-XAS), we identify the contributions to the oxygen partial density of states (p-DOS) that are crucial for OER catalysis. Our results reveal the occurrence of metal-oxygen hybridized holes, which we can correlate to the Fermi-level under oxidizing potentials. These states potentially promote the active sites as indirect electron acceptors. The nature of this metal-oxygen charge redistribution influencing catalytically active surface-structure motifs is crucial for the formation of OER intermediates. Our findings allow to revisit the role of metal and oxygen species in the OER mechanism from the viewpoint of electronic structure.

A facile and efficient methodology is described for the solvothermal synthesis of size tunable, stable, and uniform NiCu core shell nanoparticles NPs for application in catalysis. The diameter of the NPs is tuned in a range from 6 nm to 30 nm and to adjust the Ni Cu ratio from 30 1 to 1 1. Furthermore, the influence of different reaction parameters on the final NPs is studied. The NPs are structurally characterized by a method combination of transmission electron microscopy, anomalous small angle X ray scattering, X ray absorption fine structure, and X ray photoelectron spectroscopy. Using these analytical methods, it is possible to elucidate a core shell shell structure of all particles and their chemical composition. In all cases, a depletion from the core to the shell is observed, with the core consisting of NiCu alloy, surrounded by an inner Ni rich shell and an outer NiO shell. The SiO2 supported NiCu core shell NPs show pronounced selectivity of gt;99 for CO in the catalytic reduction of CO2 to CO using hydrogen as reactant reverse water gas shift reaction independent of size and Ni Cu ratio.

In the field of CO2 electroreduction CO2ER , tuning the selectivity among diverse products remains a major challenge. Mixed metal catalysts offer possible synergetic effects which can be exploited for tuning product selectivity. We present a simple wet chemical approach to synthesize a range of nickel indium mixed oxide NiAInBOx thin films with homogeneous metal distribution. CO2 electroreduction results indicate that the NiAInBOx mixed oxide thin films can achieve high CO selectivity gt;70 in contrast with the single metal oxides NiO H2 gt;90 and In2O3 formate gt;80 . The relative composition Ni40In60Ox attained the best CO selectivity of 71 at moderate cathodic bias of amp; 8722;0.8 VRHE, while a higher cathodic bias E lt; amp; 8722;0.9 V promoted a decrease of CO in favor of formate. A detailed investigation of the Ni40In60Ox thin films following progressive stages of reduction during CO2ER revealed dynamic structural transformations strongly dependent on applied bias and electrolysis time. For the CO selective catalyst composition, at moderate cathodic bias E lt; amp; 8722;0.8 V and short electrolysis times 1 h , the catalyst is composed of nickel indium alloy grains embedded in amorphous Ni In mixed oxide as observed by electron microscopy. Extending electrolysis time at amp; 8722;0.8 V for 10 h, or increasing the applied reductive bias to amp; 8722;1.0 V, result in a complete reduction of the residual oxide film into an interconnected array of multicomponent In, Ni, Ni3In7 nanoparticles which display significantly lower CO selectivity lt;50 . Our results indicate that the persistent amorphous NiInOx oxide alloy composite material preserved in the early stages of reduction at amp; 8722;0.8 V plays a key role in CO selectivity. The highly dynamic structure observed in this catalytic system demonstrates the importance of conducting detailed structural characterization at various applied potentials to understand the impact of structural changes on the observed CO2ER selectivity trends; and thus be able to distinguish structural effects from mechanistic effects triggered by increasing the reductive bias

In this work, we study the electronic and atomic structural modifications occurring in TiO2 anatase nanoparticles as anode materials in Na ion batteries upon sodiation and desodiation. The structural investigation is performed over both long and short range order by combining a comprehensive extended X ray absorption fine structure EXAFS characterization with X ray diffraction XRD . The evolution of the electronic structure upon cycling is qualitatively investigated by X ray absorption near edge structure XANES analysis. The goal of this work is to correlate the outstanding electrochemical performance of carbon coated TiO2 anatase nanoparticles in sodium batteries with the electronic and structural modifications induced during the sodiation and desodiation processes upon cycling. This work also demonstrates for the first time a coherent explanation of the structural changes observed, where an electrochemically induced short range ordering is revealed upon cycling

The morphology and structural changes of confined matter are still far from being understood. This report deals with the development of a novel

Halide perovskites are crystalline semiconductors gaining increasing attention as low-cost, high-performance materials for optoelectronics. Their processing from solution at low temperatures is compatible with rapid manufacturing of thin-film devices, including solar cells and light-emitting diodes. Therefore, understanding the coordination chemistry in metal halide perovskite precursor solutions would allow controlling the crystallization of thin films, their material properties and device performance. Here, we present a direct nanostructural technique to characterize the colloidal structure of perovskites in precursor solutions. Small-angle scattering is particularly adept for measuring nanoparticles in solution. Applying this technique to perovskite precursor solutions, we can study their colloidal properties. We show that not only do the colloids themselves matter, but also we can reveal their strong interactions in the early stages of crystallization. In particular, we focus on the prearrangement of particles into cluster-like formations. As an example, we present the concentration dependence, which is additionally supported using 207Pb NMR.

The morphology and structural changes of confined matter are still far from being understood. This report deals with the development of a novel in situ method based on the combination of anomalous small-angle X-ray scattering (ASAXS) and X-ray absorption near edge structure (XANES) spectroscopy to directly probe the evolution of the xenon adsorbate phase in mesoporous silicon during gas adsorption at 165 K. The interface area and size evolution of the confined xenon phase were determined via ASAXS demonstrating that filling and emptying the pores follow two distinct mechanisms. The mass density of the confined xenon was found to decrease prior to pore emptying. XANES analyses showed that Xe exists in two different states when confined in mesopores. This combination of methods provides a smart new tool for the study of nanoconfined matter for catalysis, gas, and energy storage applications.

The nanostructure of hydrogenated amorphous silicon (a Si:H) is studied by a combination of small-angle X-ray (SAXS) and neutron scattering (SANS) with a spatial resolution of 0.8 nm. The a-Si:H materials were deposited using a range of widely varied conditions and are representative for this class of materials. We identify two different phases which are embedded in the a-Si:H matrix and quantified both according to their scattering cross-sections. First, 1.2 nm sized voids (multivacancies with more than 10 missing atoms) which form a superlattice with 1.6 nm void-to-void distance are detected. The voids are found in concentrations as high as 6*10^19 ccm in a-Si:H material that is deposited at a high rate. Second, dense ordered domains (DOD) that are depleted of hydrogen with 1 nm average diameter are found. The DOD tend to form 10-15 nm sized aggregates and are largely found in all a-Si:H materials considered here. These quantitative findings make it possible to understand the complex correlation between structure and electronic properties of a-Si:H and directly link them to the light-induced formation of defects. Finally, a structural model is derived, which verifies theoretical predictions about the nanostructure of a-Si:H., Comment: Letter presenting a model for a-Si:H derived by SAXS and SANS

Vocal cord palsy as a result of tonsillectomy in local anesthesia is a very rare complication. In literature, there is only few publication describing this side effect of tonsillectomy. We present a case of 26 years old men who was classified for surgical removing of tonsils in local anesthesia using 1% lignocaine with 1:100 000 epinephrine. During the procedure respiratory failure with stridor was developed, examination using indirect laryngoscopy show bilateral vocal chord palsy. The authors present probably pathomechanism of this complication.

We demonstrate here a novel laboratory experiment for the synthesis of gold nanoparticles (AuNPs) by using a low energy gold-sputtering method together with a modern, green, and biofriendly deep eutectic solvent (DES). The strategy is straightforward, economical, ecofriendly, rapid, and clean. It yields uniform AuNPs of 5 nm in diameter with high reproducibility. Moreover, catalytic applications of AuNPs in DES are shown by studying the conversion of p-nitrophenol to p-aminophenol. Systematic in situ UV–vis spectra are recorded during the catalytic reaction. While the experimental procedures are simple, our laboratory experiments can be applied in a variety of settings depending upon how detailed the instructor requires the depth of the analyses. The laboratory experiments described herein were successfully conducted and evaluated by students with a bachelor degree.

Precipitation hardening involves solutionising, quenching and annealing steps, the latter often at various temperatures. The phenomena observed in Al-Mg-Si alloys are very complicated and partially not well understood. During and after quenching, solute atoms diffuse through the lattice assisted by vacancies and form atom clusters that gradually grow. These act back onto vacancies, which complicates the situation. We apply positron annihilation techniques in addition to traditional hardness, resistivity and thermal measurements to clarify what happens in various stages of thermal treatment: The quenching process can be divided into a stage of vacancy loss and of precipitation. Very short artificial ageing treatments after heating at different rates show that there is a competition between vacancy losses and cluster formation as the temperature increases. The difference between natural ageing and artificial ageing can be defined based on the importance of excess vacancies. Based on such results the behaviour of “invisible” objects such as vacancies and small clusters can be better understood but some open question remain such as the kinetics of secondary ageing or the details of the negative effect of natural ageing on artificial ageing.

We show that untwisted respectively twisted conjugacy classes of a compact and simply connected Lie group which satisfy a certain integrality condition correspond naturally to irreducible highest weight representations of the corresponding affine Lie algebra. Along the way, we review the classification of twisted conjugacy classes of a simply connected compact Lie group G and give a description of their stabilizers in terms of the Dynkin diagram of the corresponding twisted affine Lie algebra

Bimetallic nanoparticles (NPs), particularly Au/Pd and Au/Pt, have attracted extensive attention due to their wide-spread application in catalysis, optoelectronics and energy recuperation.[1] Here we have attempted the fabrication of Au/Pt and Au/Pd bimetallic NPs by an energy-efficient eco-friendly microwave methodology. The microwave-assisted reactions enable considerably large product yields over conventional colloidal methods due to (a) almost two-fold increased reaction kinetics, (b) localized superheating at reaction sites and rapid rise of initial temperature.[2] Au NPs (sizes 20 ± 3 nm) are fabricated in the first step followed by the reduction of [PdCl2(NH3)2] or [K2PtCl6]in tetraethylene glycol at 180 ºC for 2 min. Controlling and understanding the atomic structure and elemental distributions of these NPs are crucial for their optimized performances. So, we address the fundamental question of the most likely arrangement of Au and Pd or Pt atoms in these bimetallic NPs prepared under similar conditions by complementary characterizations using UV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The UV-Vis spectroscopy reveals the formation of an alloy shell. The extent of depression of the plasmon peak of Au and its blue-shift reveals substantial deposition of Pd atoms on an Au core and significant alloying in comparison to Au/Pt NPs. XRD reveals the gradual shift of the diffraction peak from the position of Au to the position of Pd or Pt with change in composition. XRD supports the formation of a thick alloy shell in these NPs. However, the TEM images reveal a very interesting result. With increase in Pt concentration, the size of the dispersed NPs decreases from 20 ± 3 nm to about 16 nm (± 1 nm) and there is evolution of a bimodal particle size distribution with small particles about 1-2 nm diameters. On the contrary, with increasing Pd concentration, the particle size of the dispersed particles increases to about 32 nm (± 1 nm). This discrepancy of particle size evolution for the two systems arises due to the differences in surface energies (Pt > Pd > Au atoms). Pt atoms tend to diffuse towards the core with the formation of Au nano-islands which eventually segregates leading to a reduction in particle size and bimodal distribution. At higher concentration of Pt, Pt and Au atoms tend to nucleate separately also contribute to the bimodal distribution. While for Au/Pd NPs, we have an Au core with an alloyed shell having higher Pd concentration. This is further supported by experimental evidence by selective etching and dissolution of Au by potassium-iodide solution. Furthermore, the Au/Pd bimetallic NPs are found to possess better catalytic activities in the reduction of 4-nitrophenol to 4-aminophenol than Au/Pt and monometallic NPs.

Mixed aerogels from semiconductor and metal nanoparticles represent an outstanding hybrid material with exceptional properties due to two striking advantages: the creation of a huge quantity of semiconductor-metal interfaces combined with a highly porous three-dimensional nanostructured network. We present a versatile synthetic pathway towards hybrid aerogels built up by joint gelation of CdTe and noble metal nanoparticles (Au, Pd and bimetallic Au/Pd). A straightforward HO treatment inducing gel formation is developed as a more elegant alternative compared to the established photooxidation approach. The use of HO allows a reproducible, simple and mild gel formation which can be easily upscaled. The tremendous influence of the HO concentration on gelation mechanism and gelation kinetics is revealed by photoluminescence quantum yield (PLQY) determinations. Resulting gels are extensively characterized via transmission electron microscopy (TEM), scanning TEM (STEM), energy dispersive X-ray analysis (EDX) as well as photoluminescence (PL) spectroscopy and PL lifetime measurements. By varying the composition of the herein presented noble metal nanoparticles in a controlled fashion the range of semiconductor-metal hybrid aerogels is widened, which demonstrates the versatility and consistency of our approach. This synthetic flexibility grants access to a variety of different mixed hybrid aerogels which are of high significance for catalytic, sensing and photonic applications., Parts of TEM investigations have been carried out at the Leibniz-Institut für Polymerforschung Dresden e.V. Access to their TEM facility is gratefully acknowledged. AD thanks the Government of the Russian Federation (Grant 074-U01) through ITMO Post-Doctoral Fellowship.

The growing challenges of environmental purification by solar photocatalysis, precious-metal-free catalysis, and photocurrent generation in photovoltaic cells receive the utmost global attention. Here we demonstrate a one-pot, green chemical synthesis of a new stable heterostructured, ecofriendly, multifunctional microcomposite that consists of α-Bi2 O3 microneedles intercalated with anchored graphene oxide (GO) microsheets (1.0 wt %) for the above-mentioned applications on a large economical scale. The bare α-Bi2 O3 microneedles display two times better photocatalytic activities than commercial TiO2 (Degussa-P25), whereas the GO-hybridized composite exhibits approximately four to six times enhanced photocatalytic activities than the neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible-light irradiation (300 W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability, and the efficient electron-hole pair separation in Bi2 O3 by individual adjoining GO sheets. The introduction of Ag nanoparticles (2.0 wt %) further enhances the photocatalytic performance of the composite over eightfold because of a plasmon-induced electron-transfer process from Ag nanoparticles through the GO sheets into the conduction band of Bi2 O3 . The new composites are also catalytically active and catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of borohydride ions. Photoanodes assembled from GO/α-Bi2 O3 and Ag/GO/α-Bi2 O3 composites display an improved photocurrent response (power conversion efficiency ∼20 % higher) over those prepared without GO in dye-sensitized solar cells.

Healable materials could play an important role in reducing the environmental footprint of our modern technological society through extending the life cycles of consumer products and constructions. However, as most healing processes are carried out by heat alone, the ability to heal damage generally kills the parent material's thermal and mechanical properties. Here we present a dynamic covalent polymer network whose thermal healing ability can be switched ‘on' and ‘off' on demand by light, thereby providing local control over repair while retaining the advantageous macroscopic properties of static polymer networks. We employ a photoswitchable furan-based crosslinker, which reacts with short and mobile maleimide-substituted poly(lauryl methacrylate) chains forming strong covalent bonds while simultaneously allowing the reversible, spatiotemporally resolved control over thermally induced de- and re-crosslinking. We reason that our system can be adapted to more complex materials and has the potential to impact applications in responsive coatings, photolithography and microfabrication., Healable materials are typically repaired by heat, which can affect the properties of the substance. Here the authors report a dynamic covalent polymer network in which light can switch the healing abilities on or off, allowing healing at defined locations without affecting the polymer as a whole.

For a simple complex Lie group G the connected components of the moduli space of semistable G -bundles over an elliptic curve are weighted projective spaces or quotients of weighted projective spaces by a finite group action. In this note we will provide a new proof of this result using the invariant theory of affine Kac–Moody groups, in particular the action of the (twisted) Coxeter element on the root system of G .

We define the Liouville functional on the set of functions on an infinite-dimensional symplectic manifold which are Hamiltonian with respect to a torus-action. In the case of finite-dimensional manifolds this functional is closely connected with the integral over the Liouville measure by a theorem due to Duistermaat and Heckman. The symplectic setup turns out to be natural for the calculation of partition functions of certain quantum field theories. In particular, among other examples, we calculate the partition function of the Wess–Zumino–Witten model on an elliptic curve in terms of this functional and deduce its modular invariance from its expression as a functional integral. In the case that the symplectic manifold is given as a generic coadjoint orbit of a loop group, the Liouville functional can be shown to give the same result as usual integration with respect to the Wiener measure.

Preliminaries.- Infinite-Dimensional Lie Groups: Their Geometry, Orbits, and Dynamical Systems.- Applications of Groups: Topological and Holomorphic Gauge Theories.

A fresh-frozen thumb osteoarthrotendinous allograft and autogenous coverage were used to reconstruct a thumb. Immunosuppressants were not used. The components of the composite allograft are present and functioning 1 year post-operatively. Host cells have replaced and are replacing bone and tendinous structures. The "survival" of this osteoarthrotendinous allograft may have important implications in the treatment of patients with previous digital amputations, congenital absence of digits, and amputated digits that have failed replantation or are not replantable because of severely damaged vessels.

The objective of this project was to evaluate the performance and economics of various domestic hot water distribution systems in representative California residences. While the greatest opportunities for improved efficiency occur in new construction, significant improvements can also be made in some existing distribution systems. Specific objectives of the project tasks were: (1) Simulate potential energy savings of, perform cost-benefit analyses of, and identify market barriers to alternative new systems. (2) Simulate potential energy savings of, perform cost-benefit analyses of, and identify market barriers to maintenance, repair, and retrofit modifications of existing systems. (3) Evaluate potential impact of adopting alternative hot water distribution systems and report project findings. The outcome of this project is to provide homeowners, homebuilders, systems suppliers, municipal code officials and utility providers (both electric and water/sewer) with a neutral, independent, third party, cost-benefit analysis of alternative hot water distribution systems for use in California. The results will enable these stakeholders to make informed decisions regarding which system is most appropriate for use.

Severe burn patients lack adequate skin donor sites to resurface their burn wounds. Patients with severe burn injuries to areas such as an entire face are presently reconstructed with skin grafts that are inferior to normal facial skin. This study was designed in part to determine whether human skin allografts would survive, repopulate, and persist on patients with immunosuppression and after discontinuation of immunosuppression. Small split-thickness skin grafts were synchronously transplanted at the time of renal transplantation from six renal transplant donors to recipients. All six patients were immunosuppressed with the usual doses of renal transplant immunosuppressants (methylprednisolone, cyclosporine, prednisone, and azathioprine). The skin allografts were biopsied when rejection was suspected and at various intervals. Special histologic studies were performed on skin biopsy specimens. Class II DNA tissue typing was performed on transplanted and autogenous skin biopsy specimens of four patients. Fluorescent in situ hybridization was performed successfully on skin biopsies of four patients' transplanted skin and on two of these four patients' autogenous skin. All six human skin allografts sustained a 100 percent take and long-term clinical survival. DNA tissue typing performed on skin allograft biopsy specimens from patients taking immunosuppressants all revealed donor and recipient cells. DNA tissue typing performed on autogenous skin biopsies from the same patients all revealed only recipient cells. Fluorescent in situ hybridization performed on allograft and autogenous specimens from patients taking immunosuppressants revealed transplanted donor cells with rare recipient cells in the allograft and only recipient cells in the autogenous skin. This study of six patients proves that it is possible for human skin allografts to survive indefinitely on patients taking the usual dosages of immunosuppressants used for renal transplantation. There was minimal repopulation of skin allografts by autogenous keratinocytes and fibroblast while patients were taking immunosuppressants. Immunosuppression was discontinued in two patients after renal transplant rejection after 6 weeks and 5 years. When immunosuppression was discontinued after 5 years in one patient, the skin allograft cells were destroyed and replaced with autogenous cells, but the skin graft did not reject acutely and persisted clinically. It is hypothesized that the acellular portion of the skin allograft was not rejected acutely because of relatively low antigenicity and because it acted as a lattice for autogenous cells to migrate into and replace rejected allograft skin cells. No chimerism was seen in autogenous skin in the skin-renal transplant patients in this study.

Patients with mild forms of tuberous sclerosis may request cosmetic treatment of skin hamartomas. Treatment may consist of planning of an elevated shagreen patch with a Reese dermatome and/or laser treatment of facial angiofibromas. These precise patients, i.e., patients with a forme fruste of tuberous sclerosis, are more likely to have pulmonary involvement than patients with the usual complete disease form. A chest x-ray should be obtained in these patients to rule out pulmonary involvement. Half the patients with pulmonary involvement of tuberous sclerosis die an avoidable death from spontaneous pneumothoraces. Positive-pressure ventilation during anesthesia in these patients should be avoided or monitored closely.

Foreign bodies in the hand are common clinical problems. A patient with a foreign body (glass) in the hand who was initially asymptomatic subsequently experienced ulnar artery erosion, thromboemboli, digital ischemia, and skin necrosis. These complications could have been prevented by removing the glass antecedent to the ulnar artery erosion. Excellent results were obtained by removal of the glass, excision of the diseased ulnar artery segment, and primary ulnar artery anastomosis.

The transplantation of a sufficient quantity of good quality skin is of great clinical importance. Severe burn patients lack adequate skin donor sites to cover their wounds with autografts. Patients with severe injuries and burns of areas such as the entire face are presently reconstructed with multiple full- or split-thickness skin grafts. The final result is a patchwork appearance of skin with inferior qualities to normal full-thickness facial skin. Before structures such as hands should be transplanted, each individual tissue component should be evaluated to determine whether the tissue will survive and function with immunosuppression. Skin is obviously an important part of the hand. One hypothesis tested is the ability of transplanted human skin to survive indefinitely with long-term immunosuppression. The early detection of rejection of transplanted organs is paramount in reversing the rejection phenomena and hence saving the transplanted organ. Another hypothesis tested is the ability of a synchronously placed, same-donor, same-recipient skin graft to be used to detect rejection of a transplanted organ. As the skin and kidney from the same donor have similar antigens and the transplantation of both these tissues is to the same recipient and immunological system, it is hypothesized that there will be a correlation of rejection between the transplanted skin and the transplanted organ. To test the above hypotheses a small skin graft was placed on renal transplant patients synchronously with renal transplantation. The skin allografts were followed by direct observation and biopsy at regular intervals and at the time of suspected rejection. The patients were treated with the usual renal transplant immunosuppressant drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple deep wrinkles and redundant skin over the dorsal hand, wrist, and forearm develop and become of cosmetic importance to some patients as they age. Distal, dorsal superior extremity plasty was performed in selected patients by excising redundant skin and wrinkles from the dorsal hands, wrists, and forearms. The area of skin to be excised is elliptical, with the long axis of the ellipse centered over the wrinkles on the dorsal wrist. The amount of skin to be excised (i.e., the short axis of the ellipse) is determined by grasping the dorsal wrist skin, hence advancing the dorsal forearm and hand skin, while the patient flexes the wrist. This maneuver is performed to avoid excessive excision of dorsal wrist skin, which would cause decreased wrist flexion. The surgical procedure is performed with use of magnification to avoid sensory nerve injury. A relatively large volume of lidocaine is injected subcutaneously to increase the distance between the skin and nerves and therefore decrease the risk of nerve injury. The skin edges are undermined for 1 to 1(1/2) cm, and the wound is closed in two layers. The wrist is splinted in 30 to 45 degrees of extension to decrease wound tension. The procedure produces long-lasting, good to excellent cosmetic improvement and patient satisfaction. The dorsal wrist, hand, and forearm appear smoother and more youthful, and scars are relatively inconspicuous. Potential significant complications include injury to the superficial branch of the radial nerve and dorsal branch of the ulnar nerve, wound dehiscence, and decreased range of motion of the wrist. Use of magnification, a bloodless field, injection of a relatively large volume of local anesthetic (10 to 12 cc), knowledge of regional anatomy, and careful surgical technique decrease the risk of nerve injury. Avoidance of injury to the superficial sensory branches of the radial and ulnar nerves is absolutely necessary for patient satisfaction. Avoidance of injury to the wound edges with good surgical technique, postoperative immobilization with the wrist in an extended position, and subsequent advancement of the wrist to a neutral position for several weeks decrease the risk of wound dehiscence. Avoidance of excessive skin excision and prolonged wrist immobilization lowers the risk of decreasing range of motion. There have been no complications in patients who underwent this procedure.

Many innovations in teaching methods have found application in mathematics classes. The authors of this article show what some of these innovations are and how they might be used.

An unusually aggressive Mycobacterium marinum infection of the hand that progressed despite surgical and medical treatment is presented. The infection progressed over a 3-week period after the patient had surgical treatment and received isoniazid (INH), rifampin, and ethambutol hydrochloride. The patient had a collar-button abscess, destruction of the metacarpophalangeal (MCP) joint capsule, flexor and extensor tenosynovitis, and metacarpal and proximal phalanx bone destruction at the MCP joint and metacarpal shaft. Although atypical mycobacterial infections of the hand are usually indolent but persistent, this Mycobacterium marinum hand infection progressed rapidly, even with surgical and medical treatment. A judgment was made to perform an index ray amputation. With a more complete excision of the infected tissue, there was a higher probability of controlling this severe infection. The patient was treated with antituberculosis medications for 6 months and is doing well 1 year after the operation.

To the Editor. —Physicians in training frequently work long hours with little sleep. After being on call, many residents drive home, creating a hazard for themselves and others on the road. Of seven surgical residents in our hospitals who we interviewed, six fell asleep while driving to or from work during their internships and three were involved in motor vehicle accidents. Residents at different levels of training in the surgical program also reported falling asleep while driving home after work. In a recent Letter from Brick and Brick, 1 a case was reported of a busy moonlighting house officer who developed an air embolus when trying to drive while simultaneously administering intravenous fluids to himself. This case, as well as the episodes we report here, argue against allowing moonlighting by house staff for their own safety as well as that of others. This occupational hazard may be minimized in a