Changes In Total Surface Area Research Articles

GROWTH TIME DEPENDENCE ON PHOTOELECTROCHEMICAL PROPERTY OF ZINC OXIDE NANORODS PREPARED BY HYDROTHERMAL SYNTHESIS

Here, the dependence of growth time on the growth behavior, morphology and photoelectrochemical (PEC) properties of ZnOnanorods (ZnO-NRs) as a photoanode are demonstrated. Vertical-aligned ZnO-NRs with [Formula: see text]-axis perpendicular to substrate were accomplished via seed-assisted hydrothermal technique at the growth time varying between 0.5 and 24[Formula: see text]h. Growth behaviors of ZnO-NRs can be described into three regimes, which consist of the nucleation stage, ZnO-NRs growth and saturation growth, respectively. ZnO nanoparticles (NPs) corresponding to the nucleation site occur at the growth time below 1[Formula: see text]h. Afterward, the growth regime of ZnO-NRs, which originated from the competition between the vertical and the lateral growth, is clearly observed, and leads to increase in length and diameter. The whole growth of ZnO-NRs is terminated after 16[Formula: see text]h, attributed to low amount of Zn[Formula: see text] and OH− supplied from growth solution. PEC measurement reveals the fast solar response and high photostability of ZnO-NRs. Additionally, the photoconversion efficiency ([Formula: see text] improves with the growth time of 4[Formula: see text]h and degrades for longer time due to the change of total surface area. The maximum [Formula: see text] of 0.13% at 0.63[Formula: see text][Formula: see text] is obtained for the growth time of 4[Formula: see text]h. Our results highlight that the growth time plays a crucial role in controlling growth behavior and the total surface area directly related with the PEC properties of ZnO-NRs.

The effect of adjunctive noncontact low frequency ultrasound on deep tissue pressure injury.

The optimal treatment for deep tissue pressure injuries has not been determined. Deep tissue pressure injuries represent a more ominous early stage pressure injury that may evolve into full thickness ulceration despite implementing the standard of care for pressure injury. A longitudinal prospective historical case control study design was used to determine the effectiveness of noncontact low frequency ultrasound plus standard of care (treatment group) in comparison to standard of care (control group) in reducing deep tissue pressure injury severity, total surface area, and final pressure injury stage. The Honaker Suspected Deep Tissue Injury Severity Scale (range 3-18[more severe]) was used to determine deep tissue pressure injury severity at enrollment (Time 1) and discharge (Time 2). A total of 60 subjects (Treatment = 30; Control= 30) were enrolled in the study. In comparison to the control group mean deep tissue pressure injury total surface area change at Time 2 (0.3 cm2 ), the treatment group had a greater decrease (8.8 cm2 ) that was significant (t = 2.41, p = 0.014, r2 = 0.10). In regards to the Honaker Suspected Deep Tissue Injury Severity Scale scores, the treatment group had a significantly lower score (7.6) in comparison to the control group (11.9) at time 2, with a mean difference of 4.6 (t = 6.146, p = 0.0001, r2 = 0.39). When considering the final pressure ulcer stage at Time 2, the control group were mostly composed of unstageable pressure ulcer (57%) and deep tissue pressure injury severity (27%). In contrast, the treatment group final pressure ulcer stages were less severe and were mostly composed of stage 2 pressure injury (50%) and deep tissue pressure injury severity (23%) were the most common at time 2. The results of this study have shown that deep tissue pressure injury severity treated with noncontact low frequency ultrasound within 5 days of onset and in conjunction with standard of care may improve outcomes as compared to standard of care only.

Modeling forced convection in the thermal simulation of laser cladding processes

A comprehensive methodology for the implementation of thermal convection into the finite element (FE) analysis of laser direct energy deposition (DED) cladding is developed and validated. Improved convection modeling will produce improved thermal simulations, which will in turn yield more accurate results from subsequent models seeking to predict microstructural changes, deformation, or residual stresses. Two common convection implementations, considering no convection or free convection only, are compared to three novel forced convection methods: forced convection from heat transfer literature, forced convection from lumped capacitance experiments, and forced convection from hot-film anemometry measurements. During the cladding process, the exposed surface, the surface roughness, and total surface area change due to material deposition. The necessity of accounting for the evolution of the mesh surface in the FE convection model is investigated. Quantified error analysis shows that using any of the three forced convection methodologies improves the accuracy of the numerical simulations. Using surface-dependent hot-film anemometry measured convection yields the most accurate temperature history, with L 2 norm errors of 6.25−22.1 ∘C and time-averaged percent errors of 2.80–12.4 %. Using a physically representative convection model applied to a continually evolving mesh surface is shown to be necessary for accuracy in the FE simulation of laser cladding processes.

Hydrogen Storage in High Surface Area Carbons with Identical Surface Areas but Different Pore Sizes: Direct Demonstration of the Effects of Pore Size

We present experimental data that directly shows the effect of pore size on hydrogen uptake in high surface area porous carbons. A direct study of the influence of pore size has been made possible by comparing the uptake capacity of porous carbons with identical surface areas but with different pore sizes and pore size distributions. A variety of synthesis methods have been used to prepare carbon materials with similar surface areas with pore sizes ranging from the micropore range (12 A) to supermicropore/lower mesopore (23 A) and lower mesopore (31 A) range. This allowed a simple and straightforward analysis of the influence of pore size without any changes in total surface area. The pore size essentially defines the hydrogen uptake with no apparent regard to the similar surface areas. The excess and total hydrogen uptake (at −196 °C and 20 bar) of carbons with identical surface areas of 3340 m2/g, increased from 3.7 and 5.4 wt % (31 A sample), to 4.8 and 6.3 wt % (23 A sample) and to 6.3 and 7.3 wt % fo...

Healing rate calculation in the diabetic foot ulcer: Comparing different methods

The determination of healing rate in the diabetic foot wound is an important assessment parameter that is part of the overall clinical decision-making process in wound treatment. A number of methods that have been used to calculate healing, ranging from length and width measurement, surface area measure changes expressed as a function of time and linear advancement of the wound edge. The objective of this study was to compare surface area measures to linear advancement of the wound edge in 228 diabetic foot ulcers. Each wound was measured using the two methods and analyzed using linear regression to determine the best modeling of the healing process in these wounds. Results indicated that the total surface area change per day was superior to the linear advancement parameter in this group of wounds and that the area measurement was significantly more likely to predict the healing trajectory in the subgroup of wounds that took more than 28 days to heal. Contrary to expectations, the linear advancement method was correlated to initial wound size in the longer duration wounds suggesting that in these chronic wounds, differing healing phases render the surface area calculation method superior to the linear advancement parameter.

Aqueous interfacial chemistry of kaolinite for the removal of Cu(II) in the presence of birnessite: Kinetic and spectroscopic studies

In this study, the aqueous interfacial chemistry of kaolinite was investigated during the removal of Cu(II) in birnessite suspensions. Adsorption kinetic experiments and X-ray absorption spectroscopy (XAS) were coupled to better understand the complexity of Cu(II) reactivity and uptake mechanisms in the mixed mineral system. Throughout all experiments (ionic strength = 0.01 M NaNO 3, [Cu] total = 100 μM), the two minerals' surface areas (6 and 8.6 m 2/500 mL) were maintained by altering the mass ratio of kaolinite (0–0.34 g) and birnessite (0–0.48 g). Copper sorption generally increased with increasing pH from 4 to 6 in all samples. The “birnessite only” system showed the fastest kinetics while the Cu uptake in the “kaolinite only” system was slowest under the respective reaction conditions. The first order kinetic model indicated that the apparent rate constants ( ka′) of kaolinite are 7.92E−6 s − 1 at pH 4 and 6.14E−6 s − 1 at pH 6. However, the addition of birnessite to kaolinite enhanced the Cu uptake when the respective systems (i.e., same surface area) were compared. For both surface areas, ka′ nearly doubled at pH 4 and was seventeen times greater at pH 6. XAS analyses show that the sorption of Jahn–Teller distorted Cu(II) octahedral molecules retain not only on birnessite surface but also on kaolinite surfaces. In the “kaolinite only” system, Cu(II) readily forms outer-sphere Cu dimer surface species (R Cu–Cu: 2.89–2.96 ± 0.02 Å, CN Cu–Cu 0.7 ± 0.2) at pH ~ 6 while the “birnessite only” system contains corner-sharing inner-sphere surface species (R Cu–Mn: ~ 3.45 Å, CN Cu–Cu 2.9 ± 0.2) in layered MnO 6 structures at pH ~ 4. Interestingly, these two surface species co-existed when the two minerals were mixed. Regardless of changes in total surface area and pH, the fraction of tridentate species in birnessite was always greater than the fraction of dimers in kaolinite. However, the fraction of tridentate corner-sharing surface species decreased with increasing pH from 4 to 6, while the dimers in kaolinite became important surface species at higher pH. The results reported in this study provide new information about the ability of kaolinite to retain metals in a mixed mineral environment. Metal surface speciation on phyllosilicate surfaces in heterogeneous media might be as important as in metal (oxyhydr)oxides in predicting metal transport processes in soils and sediments.

Molecular Origin of Constant m-Values, Denatured State Collapse, and Residue-Dependent Transition Midpoints in Globular Proteins

Experiments show that for many two-state folders the free energy of the native state, DeltaG(ND)([C]), changes linearly as the denaturant concentration, [C], is varied. The slope {m = [dDeltaG(ND)([C])]/(d[C])}, is nearly constant. According to the transfer model, the m-value is associated with the difference in the surface area between the native (N) and denatured (D) state, which should be a function of DeltaR(g)(2), the difference in the square of the radius of gyration between the D and N states. Single-molecule experiments show that the R(g) of the structurally heterogeneous denatured state undergoes an equilibrium collapse transition as [C] decreases, which implies m also should be [C]-dependent. We resolve the conundrum between constant m-values and [C]-dependent changes in R(g) using molecular simulations of a coarse-grained representation of protein L, and the molecular transfer model, for which the equilibrium folding can be accurately calculated as a function of denaturant (urea) concentration. In agreement with experiment, we find that over a large range of denaturant concentration (>3 M) the m-value is a constant, whereas under strongly renaturing conditions (<3 M), it depends on [C]. The m-value is a constant above [C] > 3 M because the [C]-dependent changes in the surface area of the backbone groups, which make the largest contribution to m, are relatively narrow in the denatured state. The burial of the backbone and hydrophobic side chains gives rise to substantial surface area changes below [C] < 3 M, leading to collapse in the denatured state of protein L. Dissection of the contribution of various amino acids to the total surface area change with [C] shows that both the sequence context and residual structure are important. There are [C]-dependent variations in the surface area for chemically identical groups such as the backbone or Ala. Consequently, the midpoints of transition of individual residues vary significantly (which we call the Holtzer effect) even though global folding can be described as an all-or-none transition. The collapse is specific in nature, resulting in the formation of compact structures with appreciable populations of nativelike secondary structural elements. The collapse transition is driven by the loss of favorable residue-solvent interactions and a concomitant increase in the strength of intrapeptide interactions with a decreasing [C]. The strength of these interactions is nonuniformly distributed throughout the structure of protein L. Certain secondary structure elements have stronger [C]-dependent interactions than others in the denatured state.

Methanethiol chemistry on TiO 2-supported Ni clusters

The thermal decomposition of methanethiol on Ni clusters grown on TiO 2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO 2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO 2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO 2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiO x and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

Tuning of texture and surface chemistry of carbon xerogels

The influence of different activation processes on the textural and surface chemical properties of carbon xerogels was studied. Carbon xerogels were prepared by the conventional sol–gel approach using resorcinol and formaldehyde; two different pHs of sol–gel processing led to carbon materials with distinct pore size distributions. The materials were subjected to controlled activation by three different methods: activation by oxygen plasma, activation by HNO 3, and activation by diluted air. Treatments with HNO 3 and diluted air created oxygen groups on the external surface as well as inside the pore channels, whereas plasma is more suitable for introducing oxygen groups selectively on the external surface. Nevertheless, it was shown that samples with wider pores can be oxidized to some extent on the pore interiors by plasma. Significant changes in total surface area by air activation were observed.

Reduction in total surface area by the develpment of microdroplets during dewetting

To meet the demand of an increasing storage density, the lubricant film for the head disk interface (HDI) needs to be thinner and stronger. In recent years, a new head/disk system, such as the contact type, has been proposed. It is reported that PFPE Zdol coated on a magnetic disk is dewetted and microdroplets are formed due to polar interactions. This makes a flying magnetic head unstable, therefore, the physics and chemistry of the dewetting phenomenon are topics of current interest. We investigated the formation and development of microdroplets using an atomic force microscope (AFM) and an optical microscope. First, we observed the disk surface coated with PFPE Zdol by AFM. From the cross section images of the microdroplets, we found that the microdroplets had a shape similar to a sphere. With this finding, we estimated the contact angle of the microdroplets in each image. The results showed that the contact angle of the microdroplet gradually decreased with time, which indicated the existence of a PFPE thin film in the dewetted area. The thickness of the PFPE film in the dewetted area was then measured using an elliposometer. Next, we investigated the variation in the number and the average diameter of the microdroplets during dewetting using images observed by the optical microscope. The total surface area change was also calculated from the observed results, and it was found that the total surface area, namely the sum of the microdroplet surfaces and dewetted area, was reduced by the development of the microdroplets.

A Dynamic Model To Study the Exchange of Gas-Phase Persistent Organic Pollutants between Air and a Seasonal Snowpack

An arctic snow model was developed to predict the exchange of vapor-phase persistent organic pollutants between the atmosphere and the snowpack over a winter season. Using modeled meteorological data simulating conditions in the Canadian High Arctic, a single-layer snowpack was created on the basis of the precipitation rate, with the snow depth, snow specific surface area, density, and total surface area (TSA) evolving throughout the annual time series. TSA, an important parameter affecting the vapor-sorbed quantity of chemicals in snow, was within a factor of 5 of measured values. Net fluxes for fluorene, phenanthrene, PCB-28 and -52, and alpha- and gamma-HCH (hexachlorocyclohexane) were predicted on the basis of their wet deposition (snowfall) and vapor exchange between the snow and atmosphere. Chemical fluxes were found to be highly dynamic, whereby deposition was rapidly offset by evaporative loss due to snow settling (i.e., changes in TSA). Differences in chemical behavior over the course of the season (i.e., fluxes, snow concentrations) were largely dependent on the snow/air partition coefficients (K(sa)). Chemicals with relatively higher K(sa) values such as alpha- and gamma-HCH were efficiently retained within the snowpack until later in the season compared to fluorene, phenathrene, and PCB-28 and -52. Average snow and air concentrations predicted by the model were within a factor of 5-10 of values measured from arctic field studies, but tended to be overpredicted for those chemicals with higher K(sa) values (i.e., HCHs). Sensitivity analysis revealed that snow concentrations were more strongly influenced by K(sa) than either inclusion of wind ventilation of the snowpack or other changes in physical parameters. Importantly, the model highlighted the relevance of the arctic snowpack in influencing atmospheric concentrations. For the HCHs, evaporative fluxes from snow were more pronounced in April and May, toward the end of the winter, providing evidence that the snowpack plays an important role in influencing the seasonal increase in air concentrations for these compounds at this time of year.

Real-Time Measurement of Exocytosis and Endocytosis Using Interference of Light

We describe a new approach for making real-time measurements of exocytosis and endocytosis in neurons and neuroendocrine cells. The method utilizes interference reflection microscopy (IRM) to image surface membrane in close contact with a glass coverslip (the “footprint”). At the synaptic terminal of retinal bipolar cells, the footprint expands during exocytosis and retracts during endocytosis, paralleling changes in total surface area measured by capacitance. In chromaffin cells, IRM detects the fusion of individual granules as the appearance of bright spots within the footprint with spatial and temporal resolution similar to total internal reflection fluorescence microscopy. Advantages of IRM over capacitance are that it can monitor changes in surface area while cells are electrically active and it can be applied to mammalian neurons with relatively small synaptic terminals. IRM reveals that vesicles at the synapse of bipolar cells rapidly collapse into the surface membrane while secretory granules in chromaffin cells do not.

Formation of Nanostructures in UO2Fuel at High Burn-ups

In the present paper it is assumed that above a limiting value of fission fluency (burn-up) a more intensive process of irradiation induced chemical interaction occurs. A significant part of fission gas product is thus expected to be chemically bounded in the matrix of UO 2 fuel. The fission gas atoms substituting, for example, uranium atoms in the crystallographic lattice can form weak facets. At a certain saturation condition, division of the grains can occur at the weak facets and the increase in fission-gas-products release may be expected. The fact that the process of grain division for high burn-ups (70-80 MWd/kgU) forms an extremely fine structure up to a temperature as high as 1100°C and simultaneously the observed decrease in fission gas concentration in the fuel supports this concept. The analysis of fission gas concentration change due to the formation of nanostructures in UO 2 fuel at high burn-ups in terms of total surface area change in a function of burn-up and knock-out process is presented.

Randomized controlled trial of cyclosporine for treatment of perianal fistulas in dogs

Objective To evaluate efficacy of cyclosporine for treatment of perianal fistulas in dogs. Design Randomized, controlled trial. Animals 20 German Shepherd Dogs with naturally developing perianal fistulas. Procedure 10 dogs were treated with cyclosporine; the other 10 dogs were given a placebo. Overall improvement and change in total surface area of involvement and depth of the deepest fistula were determined after 4 weeks. Thereafter, cyclosporine-group dogs were treated for an additional 12 weeks and control-group dogs were treated with cyclosporine for 16 weeks. Results All cyclosporine-group dogs, but none of the control-group dogs, were subjectively improved after 4 weeks. Mean total surface area and mean fistula depth decreased 78 and 62%, respectively, in the cyclosporine-group dogs but increased 29 and 11%, respectively, in the control-group dogs. After 16 weeks of cyclosporine treatment, fistulas had healed in 17 (85%) dogs. However, fistulas recurred in 7 of 17 dogs, and additional cyclosporine treatment or anal sacculectomy and surgical excision of fistulas was necessary. Clinical Implications Cyclosporine appeared to be effective in dogs with perianal fistulas. Even in dogs in which fistulas were not completely healed, cyclosporine administration appeared to be beneficial, because the surgical procedures that were required were less extensive than those that would have been necessary if cyclosporine had not been given. (J Am Vet Med Assoc 1997;211:1249–1253)

Changes in Fracture Surface Area and Actual Fracture Energy of a Carbon Fiber-Reinforced Silicon Nitride Composite during Failure

The change in total surface area, namely fracture surface area, of a carbon fiber-reinforced silicon nitride composite (unnotched specimens) was measured by the BET adsorption technique during loading/unloading tests in three-point bending. The actual fracture energy of unnotched specimens, which had been defined as the ratio of the work done during one cycle of loading/unloading to the fracture surface area, was compared with that of notched specimens reported previously. Changes in fracture surface area and actual fracture energy corresponded to the transition of fracture mechanism during failure, and obviously reflected the difference in the damage process of the specimens with and without notch. The actual fracture energy had a physical meanings close to the effective fracture energy ordinary reported when the main fracture mechanism was the macroscopic crack extension. It was considered that the evaluation of fracture surface area and actual fracture energy was an effective method to investigate fracture behavior of fiber-reinforced ceramic composites.

The role of microporous surface area in the gasification of chars from a sub-bituminous coal

The role of microporous surface area in the CO 2 gasification of chars from a sub-bituminous coal was investigated. There is evidence that the reaction primarily takes place outside the microporous network on the surfaces of larger pores. The rate of gasification is insensitive to large changes in total surface area occurring during heat treatment or reaction. This behaviour is consistent with the occurrence of reaction on active sites lying preferentially outside the micropores. Mechanisms which can lead to an enhancement of the active site concentration on large pore surfaces are discussed.

The concept of active sites applied to the study of carbon reactivity

The reactivity of a carbon toward oxygen depends on several surface and bulk properties: specific surface area, porosity, crystallinity and level of impurities. In the present article, an attempt to compare the reactivity of carbon having various types of texture and a low level of impurities content has been undertaken. The change in total surface area (TSA) and in active surface area (ASA) has been followed during oxidation. For carbon heat-treated at 2000°C, the rate of gasification with respect to ASA does not markedly change during oxidation and is about the same for all studied samples.

Some aspects of the thermal annealing process in a phenol-formaldehyde resin char

It is well known that chars and carbons lose reactivity as a function of the severity of their heat treatment in inert environments. In this study, phenol-formaldehyde resins of low impurity contents were prepared and heat treated at heat treatment temperatures (HTT) ranging from 1273 K to 1673 K. The low-temperature oxygen reactivity of the chars was then measured, both in the oxygen chemisorption regime (423 K, 101 kPa O 2) and the oxygen gasification regime (573–673 K, 0.5 to 101 kPa O 2). The oxygen gasification reactivity varied with heat treatment by an order of magnitude. It was concluded that this was not entirely attributable to changes in total surface area with heat treatment. The variation of the reactivity to active surface ares (ASA) ratio with burnoff was small in 1273 K char and large in 1673 K char. The kinetics of annealing were explored, and it was found that a single firstorder deactivation reaction model was unable to describe the variation of either reactivity or ASA with HTT. A first-order distributed activation energy model was found to fit the data reasonably, and implied that the deactivation reactions that are of relevance under these conditions have a preexponential factor of between 10 13 and 10 14 s −1, and activation energies in excess of 450 kJ/mole.

Evolution of pore structure and active surface areas of coal and char during hydrogenation

A Belgian coal (Beringen) has been used in a fundamental study of the changes in pore structure and active surface area during hydrogenation. The coal was devolatilized under N 2 and then hydrogenated at constant temperature up to various conversion yields. Reactivities of the chars were determined by isothermal thermogravimetric analysis. Changes in total surface area, calculated from CO 2 adsorption isotherms at 298 K, and in macropore distribution, obtained by mercury penetration, were found to lead to the same conclusion. In the first reaction stage, the preponderant phenomenon was the opening of previously closed micropores, induced by the material consumed by the reaction. This stopped completely when conversion yield exceeded 55 wt% when the maximum surface area was observed. Then removal of material from pore walls became predominant, pores were enlarged and pore walls disappeared gradually with increasing hydrogenation yields. Oxygen chemisorption capacities were measured at 383 K and 0.1 MPa air to give a relative indication of the concentration of carbon active sites. Active surface area results were compared to total surface area values and correlated with reaction rates.

Temperature of Comet IRAS-Araki-Alcock (1983d)

Infrared (1.5–20 μm) observations of the nuclear condensation of Comet IRAS-Araki-Alcock (1983d) during the interval 5–8 May 1983 (UT) show that the distribution of 3.5- to 20-μm radiation was blackbody in character with no evidence of 10-μm emission from silicate grains in the coma of the comet. The observed color temperature of the nuclear condensation of the comet was 319 ± 5°K on 7 May and 307 ± 5°K on 8 May. Low-resolution spectrophotometry on 5 May in the 1.5- to 2.6-μm region shows no obvious emission or absorption features, but thermal radiation of approximately the same color temperature as the 3.5- to 20-μm radiation was present along with reflected sunlight. Scans of the nuclear region of the comet indicate that most of the thermal radiation observed at 11.6 and 20.0 μm came from an ≤120-km-diameter, unresolved area centered on the nuclear region. Absolute flux measurements suggest that projected areas (unit emissivity) of 70 and 40 km 2 were responsible for the thermal radiation from the nuclear condensation on 7 and 8 May, respectively. This large change in total surface area suggests that the amount of dust in the nuclear region of Comet 1983d was highly variable and is consistent with the observation by M.A. Feierberg, F.C. Witteborn, J.R. Johnson, and H. Campins (1984, Icarus, 60, 449–454) of an outburst on 11 May 1983.