Radial Surfaces Research Articles

Electrical Facility Effects on Hall Thruster Cathode Coupling: Performance and Plume Properties

The impact of facility conductivity on Hall effect thruster cathode coupling is experimentally investigated. The 3.4 kW Aerojet Rocketdyne T-140 Hall effect thruster operating at a discharge voltage of 300 V, a discharge current of 10.3 A, and an anode flow rate of serves as a representative Hall effect thruster test bed. The nominal facility operating pressure during thruster operation is corrected for xenon. Two square aluminum plates are placed adjacent to, but electrically isolated from, the walls of the conductive vacuum chamber at two locations with respect to the center of the thruster exit plane: 4.3 m axially downstream along the thruster centerline, and 2.3 m radially outward centered on the exit plane. The plates and body of the Hall effect thruster are configured in three distinct electrical configurations with corresponding measurements: 1) electrically grounded with measurements of currents to ground, 2) electrically isolated with measurements of floating voltages, and 3) isolated from ground but electrically connected with measurements of the current conducted between the plates. Measurements are taken as the radial position of the cathode is varied from 0 to 129 cm with respect to the nominal cathode location. Measurements of the current collected by the plates and thruster body indicate that cathode electrons preferentially travel to the thruster body, Hall effect thruster plume, and radial facility surfaces for cathode locations in the near field, midfield, and far field, respectively. These results indicate that cathode position alters the recombination pathways taken by cathode electrons in the Hall effect thruster circuit.

Hydraulic traits of Norway spruce sapwood estimated by Fourier transform near-infrared spectroscopy (FT-NIR)

The potential of Fourier transform near-infrared (FT-NIR) spectroscopy to predict hydraulic traits in Norway spruce (Picea abies (L.) Karst.) sapwood was evaluated. Hydraulic traits tested were P50 (applied air pressure causing 50% loss of hydraulic conductivity) and RWL50 (applied air pressure causing 50% relative water loss). Samples came from 24-year-old spruce clones. FT-NIR spectra were collected from the axial (transverse) and radial surface of each solid wood sample for the prediction of P50 and RWL50. Partial least squares regression (PLS-R) models with cross validation were used to establish relationships between the FT-NIR spectra and the reference data from hydraulic properties analysis. The impact of the wavenumber range and the pretreatment during the PLS-R model development and the differences between the axial and radial surfaces were shown. Based on the values of the coefficient of determination (r2) and the root mean square error of cross validation, predicted results were evaluated as acceptable. The models from the axial surface gave better results than the models from the radial surface for P50 (r2 = 0.65), as well as for RWL50 (r2 = 0.77). The first approach to predict hydraulic properties such as P50 and RWL50 by FT-NIR spectroscopy can be regarded as successful. We conclude that the method has high potential to be put into practice as a rapid, reliable, and nondestructive method to determine P50 and RWL50.

Water uptake and wetting behaviour of furfurylated, N-methylol melamine modified and heat-treated wood

This study reports on the water uptake (WU) and wetting properties of different modified wood materials; furfurylated and N-methylol melamine (NMM) modified Scots pine, and heat-treated (Vacu3 method) Scots pine and beech. All modifications caused a substantial reduction in WU in the longitudinal, tangential and radial directions both after short (24 h) and long contact times (168, 336 h) with a saturated sponge. The water uptake coefficient (w t ) was reduced by approximately 71–89 % in furfurylated wood, with the higher weight percent gain (WPG) providing a slightly greater reduction. The reduction in WU was not found to depend on the NMM solid content. The NMM treatment had the maximum effect on the reduction of tangential w t by 80–84 % and was much smaller in the longitudinal direction (31–68 %). The treatment temperature of 195 °C gave lower WU values than treatment at 210 °C, and the only exception was the radial direction of Scots pine. The longitudinal w t of heat-treated beech represented the highest reduction by 81–89 %, while radial w t was less affected in both species. Sessile drop apparent contact angles for water and diidomethane and corresponding surface energies on planed tangential and radial wood surfaces revealed an increased hydrophobicity and reduced polarity of modified wood. Furfurylated and NMM modified tangential surfaces had a higher increase of apparent contact angles than the radial surfaces but this was not observed in the case of heat treatment. Heat-treated wood showed reduced wetting of surfaces only with water. Apparent contact angles did neither differ with treatment temperature nor with the NMM resin load. The disperse component of surface energy was slightly increased by 20 % maximum in modified wood, while the polar components showed a dramatic decrease by −30 to −90 % with no major differences among treatments and intensities, and between surfaces. The results provide a better understanding of the hygroscopic behaviour of modified wood, which might be useful to predict its adhesion with various polymers such as glues, coatings and paints.

Using a local gyrokinetic code to study global ion temperature gradient modes in tokamaks

In this paper the global eigenmode structures of linear ion temperature gradient (ITG) modes in tokamak plasmas are obtained using a novel technique which combines results from the local gyrokinetic code GS2 with analytical theory to reconstruct global properties. Local gyrokinetic calculations are performed for a range of radial flux surfaces, x, and ballooning phase angles, p, to map out the local complex mode frequency, Ω0(x, p) = ω0(x, p) + iγ0(x, p) for a single toroidal mode number, n. Taylor expanding Ω0 about a reference surface at x = 0, and employing the Fourier-ballooning representation leads to a second order ODE for the amplitude envelope, A(p), which describes how the local results are combined to form the global mode. The equilibrium profiles impact on the variation of Ω0(x, p) and hence influence the global mode structure. The simulations presented here are based upon a global extension to the CYCLONE base case and employ the circular Miller equilibrium model. In an equilibrium with radially varying profiles of a/LT and a/Ln, peaked at x = 0, and with all other equilibrium profiles held constant, including ηi = Ln/LT, Ω0(x, p) is found to have a stationary point. The reconstructed global mode sits at the outboard mid-plane of the tokamak, with global growth rate, γ ∼ Max[γ0]. Including the radial variation of other equilibrium profiles like safety factor and magnetic shear, leads to a mode that peaks away from the outboard mid-plane, with a reduced global growth rate. Finally, the influence of toroidal flow shear has also been investigated through the introduction of a Doppler shift, , where Ωϕ is the equilibrium toroidal flow, and a prime denotes the radial derivative. The equilibrium profile variations introduce an asymmetry into the global growth rate spectrum with respect to the sign of , such that the maximum growth rate is achieved with non-zero shearing, consistent with recent global gyrokinetic calculations.

Effects of circumferential and radial rough surfaces in a non-Newtonian magnetic fluid lubricated squeeze film

The effects of surface roughness in circular squeeze film disks lubricated with a non-Newtonian magnetic fluid are investigated in this paper. Employing the stochastic model together with the microcontinuum theory and the ferromagnetic flow model, a non-Newtonian magnetic-fluid lubricated Reynolds equation including the influences of rough surfaces is derived, and applied to predict the squeeze film performances. According to the results, the surface roughness effects of circumferential structures increase the mean load capacity and lengthen the mean approaching time as compared to those of the smooth disks with a non-Newtonian magnetic fluid. However, the radial roughness patterns yield a reversed trend. In addition, the effects of rough surfaces on the squeeze film characteristics are more pronounced for circular disks operating with larger values of the surface roughness parameter, the non-Newtonian couple stress parameter, the volume concentration parameter and the magnetic Langevin parameter.

A SEM study on the use of epoxy functional vegetable oil and reactive UV-absorber as UV-protecting pretreatment for wood

The present study investigates the ageing performance of a UV protective system for wood, comprising the reactive UV absorber 2-hydroxy-4(2,3-epoxypropoxy)-benzophenone (HEPBP) and epoxy functional vegetable oils (linseed and soybean oil). Scots pine samples of radial or cross-sectional surfaces were treated using a combination of the two components, or using only one of the oils. The treated samples were then aged in a Weather-Ometer for 2 × 60 h and analysed using VPSEM to follow the degradation of the wood substrate in the exact same spot before, during and after ageing. The results of the radial surfaces show slightly less degradation of samples treated with a combination of HEPBP and oil, and for the cross-sectional surfaces an even stronger protective effect is visible. For samples treated with only one of the two oils, no improvement was detectable. The radial surfaces were also analysed using FTIR where the results indicate presence of the protective treatment even after 120 h of exposure. Overall the combined pretreatment of HEPBP and epoxy functional linseed oil was concluded to have a photostabilising effect of the wood substrate.

Equine Articular Cartilage Stiffness Determination Using Indentation

In order to determine that the stiffness varies between different joint types, an indentation test was performed on fresh equine articular cartilage surfaces from the fetlock, carpal, and stifle joints. The results demonstrated that the stiffness varies on different joints showing different mechanical behaviors. A flat-ended cylindrical indenter is lowered at a constant rate for 20 s until the indentation depth reaches 0.2 mm (velocity of 10 μm/s). It was shown that the articular cartilage of the fetlock is stiffer than the carpal and stifle joints. The average stiffness of the fetlock, carpal, and stifle joints are 46.1 N/mm, 20.5 N/mm, and 2.73 N/mm, respectively. The coefficients of a fit for the joints were statistically compared as well using the student t-test. The differences of some coefficients between the fetlock, carpus, and stifle were “very highly significant” (p < 0.001). Four different surfaces in the fetlock and four in carpal joint were compared as well. The front lateral, front medial, rear lateral, and rear medial cartilage surfaces in the fetlock were not significantly different in stiffness. In the carpus, the distal radius and proximal radial carpal bone articular cartilage surfaces showed significantly different stiffness from the others, while the distal radial carpal bone and proximal third carpal bone articular cartilage surfaces possessed similar stiffness values. The cartilage surfaces from the radiocarpal joint were stiffer than the midcarpal joint. Clear trends in the correlations between stiffness and weight as well as stiffness and age of the horse were not observed.

Comparison of equine articular cartilage thickness in various joints

Purpose: Thicknesses of fresh equine articular cartilage surfaces from the fetlock, carpal and stifle joints were measured employing a needle probe test.Materials and methods: Eighty-seven samples used in measurement were cultivated from fetlock, carpal and stifle joints of 12 deceased within 4 h of death. After approximately three minutes of exposure to air during dissection, all cartilage samples were preserved in a saline solution to keep the articular cartilage hydrated for testing. The thickness was measured on five different spots on the same sample. The thicknesses of the fetlock, carpus and stifle were compared.Results: The articular cartilage of the stifle was thicker than the fetlock and carpus, while the fetlock and the carpus had similar thickness values. The average thickness of the fetlock, carpal and stifle joint are 0.86, 0.87 and 2.1 mm, respectively. They were statistically compared using the Student t-test. The differences on the articular cartilage thicknesses between the fetlock and stifle, and carpus and stifle were “very highly significant” (p < 0.001). This indicates that the articular cartilage thickness of the stifle is significantly different from that of the fetlock and carpus. Four different surfaces in the fetlock and four in the carpal joint were also compared. Significant differences between each set of the four surfaces were not observed. In the carpus, the difference in thickness between the distal radius and proximal third carpal bone articular cartilage surfaces as well as the proximal radial carpal bone and distal radial carpal bone articular cartilage surfaces were statistically significant.

Static and kinetic friction coefficients of Scots pine (Pinus sylvestris L.), parallel and perpendicular to grain direction

In this study the static (µe) and kinetic (µd) coefficients of friction were obtained for Pinus sylvestis L. sawn timber of Spanish origin. Friction between transverse surfaces sliding perpendicular to the grain (tangential direction) and radial surfaces sliding parallel to the grain was analyzed. A specifically designed device was used for tests, which makes it possible to apply contact pressure and measure displacements and applied loads simultaneously. Coefficients of friction between transverse surfaces (µe = 0,24; µd = 0,17) were about twice of the coefficients of friction between radial surfaces (µe = 0,12; µd = 0,08). Furthermore, these values are located within normal values of those commonly reported for softwood. The results are considered preliminary due to the small number of specimens.

Influence of lateral initial pressure on axisymmetric wave propagation in hollow cylinder based on first power hypo-elastic model

Influence of identical applied initial pressures on the radial surfaces of a hollow cylinder which is compose of materials with first power hypo-elastic constitutive model was investigated. The basic equations of the problem were built up based on the framework of piecewise homogeneous body model with the use of three-dimensional linearized theory of elastic waves in initially stressed bodies (TLTEWISB). With the method proposed previously, this problem was then solved numerically. Moreover, the dispersion group velocity of the lowest order mode with different initial pressures was also studied. It can be concluded that the initial pressure and the geometry parameters will induce considerable changes of different degrees in dispersive relation between phase velocity and wave number in opposite trend (positive in initial pressure and negative in thickness).

Preliminary modeling of the oil trapping between teeth for spur gears

This study focuses on the phenomenon of oil trapping in the tooth spaces of spur gears. It presents the first obtained results in order to provide an estimation of the power losses due to the compression of the oil trapped between the inter teeth meshing spaces in a high-speed transmission for internal and external spur gears. It first allows, to model the inter teeth spaces at any time and offers limits for the trapped fluid volume and axial and radial discharge surfaces. The discretization impact result is discussed.Then, the influence of certain design and operating parameters such as module, pressure angle, addendum modification coefficient and rotational speed on these discharge surfaces and trapped volume is presented.

The relationship between the arrangement of rays in secondary phloem and grain inclination in the wood of Pinus silyestris L. and Picea abies Karst

The arrangement of rays in cross sections of secondary phloem and the wood grain on the tangential and radial surfaces of wood columns from &lt;i&gt;Pinus silvestris&lt;/i&gt; and &lt;i&gt;Picea abies&lt;/i&gt; was studied. It was found that in most cases the rays were slanted and deviated from the geometric radius in either the S-direction (to the left) or in the Z-direction (to the right) when the cross section of the stem was observed from above. The S-type deviation dominated in those stems in which the wood grain in the peripheral parts was of the S-type (left-oriented), whereas the deviation of rays in the Z-direction was found to dominate in those objects, in which the wood grain in the peripheral parts of the stem was of the Z-type (right-oriented).

Pattern of bone erosion and bone proliferation in psoriatic arthritis hands: a high-resolution computed tomography and radiography follow-up study during adalimumab therapy

Objectives: To investigate the pattern and development of bone erosion and proliferation in patients with psoriatic arthritis (PsA) during treatment with adalimumab, using high-resolution computed tomography (CT) and conventional radiography.Method: Forty-one biologic-naïve PsA patients were initiated with adalimumab 40 mg subcutaneously every other week. CT and radiography of the 2nd–5th metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints were conducted at baseline (n = 41) and after 24 weeks (n = 32). Changes in bone erosion and proliferation are described and the imaging modalities compared.Results: Ninety percent of bone erosions detected by CT were located in the metacarpal heads, and most frequently in the 2nd-3rd MCP joints. Radial (37%) and ulnar (31%) surfaces were more frequently eroded than dorsal (10%) and palmar (22%) sites. Using CT, bone proliferations were located primarily on the sides of the distal part of the DIP joints (43% of all proliferations), but also proximally in DIP (17%) and MCP joints (27%). For bone erosions and proliferations, respectively, radiography showed a low sensitivity (17% and 26%), but a high specificity (98% and 95%) and accuracy (93% and 87%), with CT as the gold standard reference. Neither CT nor radiography revealed statistically significant changes in bone erosion or proliferation scores between baseline and follow-up.Conclusions: Patterns of bone erosion and proliferation in PsA hands were revealed in more detail by CT than by radiography. No overall progression or repair could be detected during adalimumab treatment with either of the methods.

Effect of Densification Temperature and Some Surfacing Techniques on the Surface Roughness of Densified Scots Pine (Pinus sylvestris L.)

The effects of densification temperature, planing, circular sawing, and sanding on the surface roughness of densified Scots pine using the open-system thermodynamic method were studied. Densification was applied to Scots pine at 6 MPa pressure and at temperatures of 120 °C, 140 °C, and 160 °C. A total of 1040 specimens (160 × 50 × 10 mm) were prepared using the surfacing techniques of planing, circular sawing, and sanding. The surface roughness of the specimens were measured in conformance with the TS 2495, EN ISO 3274, and the TS 6212 EN ISO 4288 standards, and the results were subjected to statistical analysis. The surface roughness of the planed surfaces was 26% lower, of the surfaces cut circularly was 38% lower, and of the sanded surfaces was 32% lower in densified Scots pine compared to undensified Scots pine. According to the densification temperature, while the lowest roughness was obtained in the densified specimens at 140 °C, raising the temperature to 160 °C increased the roughness. An increase in the number of blades in planing, the tooth number in circular sawing, and the grit number in planing decreased the surface roughness. Furthermore, the roughness was less in tangential surfaces compared to radial surfaces.

Dynamic stiffness of hollowed cylindrical rubber vibration isolators — The wave-guide solution

The dynamic stiffness of hollowed cylindrical vibration isolators using a wave-guide modelling approach is given. The isolators consist of rubber and metal elements in series. The boundary conditions at the lateral and radial surfaces of each rubber component are locally non-mixed and simultaneously satisfied by using the modes corresponding to the dispersion relation for axial waves in infinite hollow cylinders while the metal plates are assumed rigid, following Newton’s second law. The modes of the rubber elements exactly satisfy the stress free boundary conditions at the curved radial boundaries, while the displacement conditions on the flat cylinder ends are satisfied in mean by a mode matching approach. The rubber is modelled as nearly incompressible with deviatoric visco–elasticity based on a fractional derivative, standard linear solid. The stiffness is found to depend strongly on frequency, displaying resonances and anti-resonances. Further, results indicate a great potential for optimising vibration isolators of the studied kind. By choosing appropriate combinations of metal plates and rubber elements, the dynamic transfer stiffness in higher frequency bands can be suppressed to be magnitudes lower than the static stiffness, a highly sought feature in vibration isolators. Finally, simplified models including mass-spring systems and the long rod theory are implemented and compared to the derived formulation.

CT arthrography of the wrist using a novel, mobile, dedicated extremity cone-beam CT (CBCT)

To evaluate the feasibility and intra- and interobserver agreement of CBCT arthrography of wrist ligaments, triangular fibrocartilaginous complex (TFCC), and to assess the sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive value (PPV, NPV) of CBCT arthrography in the diagnosis of scapholunate (SLL) and lunotriquetral (LTL) ligament tears, TFCC, and cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) using a novel, mobile, dedicated extremity CBCT scanner. Fifty-two consecutively enrolled subjects (26 M, 26 F, mean age 38 years, range 18-66 years) with suspected wrist ligament tears underwent CBCT-arthrography before normally scheduled MR arthrography.An extremity CBCT was used for imaging with isotropic voxel size of 0.4 × 0.4 × 0.4 mm(3). Subsequent routine 1.5 T MRI was performed using a dedicated wrist coil.Two observers reviewed the anonymized CBCT images twice for contrast enhancement (CE) and technical details (TD), for tears of the SLL, LTL, and TFCC. Also, cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) were evaluated. Inter- and intraobserver agreement was determined using weighted kappa statistics. Since no surgery was performed, MRI served as a reference standard, and SE and SP, ACC, PPV, and NPV were calculated. Intra- and interobserver kappa values for both readers (reader 1/reader 2; first reading/second reading) with 95 % confidence limits were: CE 0.54 (0.08-1.00)/ 0.75 (0.46-1.00); 0.73 (0.29-1.00)/ 0.45 (0.07-0.83), TD 0.53 (0.30-0.88)/ 0.86 (0.60-1.00); 0.56 (0.22-0.91)/ 0.67 (0.37-0.98), SLL 0.59 (0.25-0.93)/ 0.66 (0.42-0.91); 0.31 (0.06-0.56)/ 0.49 (0.26-0.73), LTL 0.83 (0.66-1.00)/ 0.68 (0.46-0.91); 0.90 (0.79-1.00)/ 0.48 (0.22-0.74); TFCC (0.72-1.00)/ (0.79-1.00); 0.65 (0.43-0.87)/ 0.59 (0.35-0.83), radius (scaphoid fossa) 0.45 (0.12-0.77)/ 0.64 (0.31-0.96); 0.58 (0.19-0.96)/ 0.38 (0.09-0.66), scaphoid 0.43 (0.12-0.74)/ 0.76 (0.55-0.96); 0.37 (0.00-0.75)/ 0.32 (0.04-0.59), radius (lunate fossa) 0.68 (0.36-1.00)/ 0.42 (0.00-0.86); 0.62 (0.29-0.96)/ 0.51 (0.12-0.91), and lunate 0.53 (0.16-0.90)/ 0.68 (0.44-0.91); 0.59 (0.29-0.88)/ 0.42 (0.00-0.84), respectively. The overall mean accuracy was 82-92 % and specificity was 81-94 %. Sensitivity for LTL and TFCC tears was 76-83, but for SLL tears it was 58 %. For cartilage abnormalities, the accuracy and negative predictive value were high, 90-98 %. A dedicated CBCT extremity scanner is a new method for evaluating the wrist ligaments and radiocarpal cartilage. The method has an overall accuracy of 82-86 % and specificity 81-91 %. For cartilage abnormalities, the accuracy and negative predictive value were high.

Impact of Kiln Drying Schedule upon Some Mechanical Properties of Poplar Wood

In the present research, the effect of three kiln drying schedules of T5-D2, T5-D4, and T5-D6 on poplar wood mechanical properties was investigated. The lumber was dried in a convectional laboratory kiln and then the compression strength in a parallel and perpendicular direction toward the grain, hardness, and nail withdrawal resistance were evaluated. The obtained results indicated with change from schedule T5-D2 to T5-D4, compression strength whether parallel or perpendicular to grain, hardness in tangential, radial, and transverse surfaces as well as, nail withdrawal resistance in tangential, radial, and transverse surfaces increased up to 18.1, 7.1, 16.4, 19.7, 14.1, 19.8, 5.7, and 9.2 % respectively, as against schedule T5-D2. Despite T5-D4 schedule, compression strength parallel to grain dropped in specimens dried by schedule T5-D6. However, nail withdrawal resistance of specimens dried by T5-D6 schedule was higher in all the three surfaces than the two other schedules. As regards, the T5-D6 schedule, compression strength perpendicular to grain and also hardness in all the three surfaces rose as opposed to that of T5-D2 schedule, but showed a decrease in comparison to the corresponding figure in T5-D4. Moreover, statistical analysis revealed that except the compression strength perpendicular to grain, other mechanical strength inducing by various wood drying conditions were put in separate statistical groups.

Use of an Iliac Crest Growth Plate for the Development of a Neo-articulation for Congenital Transverse Deficiencies at the Wrist

Terminal congenital transverse deficiencies of the wrist and hand are rare malformations. They are usually treated with prosthetic devices. We describe here a surgical technique to create a neo-articulation that could provide mobility distal to the forearm and help children with terminal transverse deficiencies use orthotic devices. This procedure involved an autologous, nonvascularized graft from the immature iliac crest. The graft was placed with its cartilaginous side facing the radial and ulnar articular surfaces. We studied the clinical, radiological, and functional outcomes of this technique in 2 pediatric cases 5 and 14 years after this procedure. The x-rays showed a mobile graft distally in the forearm. Magnetic resonance imaging showed a space between the graft and the radius and an intermediate signal on either side of the space highly suggestive of articular cartilage. These various elements were organized into a neo-articulation between the forearm and the graft. The functional ability at follow-up was greater compared with the absence of a graft. The results of basic research work on cartilage and chondrocytes may help explain the presence of persistent cartilaginous tissue on the articulated part of the graft. The good functional outcome provided by our surgical procedure may translate into reduced need for prosthesis acceptance. Our surgical procedure does not restore limb length, but does add a new functional ability. Therapeutic IV.

Influence of the viscosity of UF resins on the radial and tangential penetration into poplar wood and on the shear strength of adhesive joints

Abstract This paper is the final part of a series reporting on the penetration (P) and bonding behaviour of urea-formaldehyde (UF) resins of different viscosities based on different degrees of condensation (DCs). The various resins were applied onto radial and tangential wood surfaces, and solid wood assemblies were prepared by hot pressing. Pt and Pr were observed by evaluation of photomicrographs of the bond lines. The mean and maximum depth of penetration was inversely proportional to the DC. The average depth of Pt was found to be slightly higher than Pr because of the abundance of pits on the radial walls. However, the maximum P was higher in radial direction, due to the elliptic shape of vessels in poplar as well as due to rays improving the resin flow. The lap shear strength (σm) of the same bonded assemblies was determined. Despite the fact that the wood failure always was very high, the σm increased with the better penetration of the resins with low viscosity. The higher strength values measured has been interpreted as a fortification effect of the interphase by bulk resin penetration, as cell wall penetration cannot be expected due to the large size of such resin molecules.

Erosive plaques on the dorsal surfaces of the hands

From Yo D M Fund Conf Repr D An otherwise healthy 58-year-old woman presents with a 10-day history of ulcers on the dorsal surfaces of both hands. The initial lesion, an expanding pustule, became bullous and erosive. She subsequently developed large bullous hemorrhagic plaques on both forearms. The patient denies systemic symptoms, oral or genital ulcers, sick contacts, recent travel, contact with chemicals, or new medications. The physical examination reveals large eroded exophytic erythematous plaques with overlying bullae on the dorsal surfaces of her hands and forearms (Fig 1). An outside punch biopsy specimen is obtained and reveals a diffuse neutrophilic infiltrate throughout the dermis with focal vasculitis. Stains for fungi and bacteria are negative. A repeat biopsy is performed (Fig 2). Based on clinical and histopathologic findings, the patient is diagnosed with neutrophilic dermatosis of the dorsal hands (NDDH), a rare entity included in a spectrum of conditions known as neutrophilic dermatoses (characterized by a predominantly neutrophilic inflammatory infiltrate). NDDH classically presents acutely as violaceous indurated plaques on the dorsal radial surfaces of the hands.