Low Surface Density Research Articles

Ethylene for carbon doping of GaN by atmospheric pressure metal organic chemical vapor deposition

The carbon incorporation properties of GaN from ethylene and trimethylgallium precursors was studied by atmospheric pressure metal organic chemical vapor deposition. It is found that V-III ratio was the main restriction factor for carbon incorporation. Carbon concentration could be regulated effectively one order of magnitude by tuning V-III ratio for C2H4 doped GaN, and would be enhanced at relatively low V-III ratio for self-doped GaN. Low threading dislocation density and atomic flat surface of C2H4 doped GaN films was kept even if carbon doping concentration of 9E18/cm3 compared with UID-GaN and a high breakdown voltage of 2278 V at leakage current of 10µA was obtained in C2H4 doped GaN buffer layer.

The influence of the capping ligands on the optoelectronic performance, morphology, and ion liberation of CsPbBr3 perovskite quantum dots

Perovskite quantum dots (PeQDs) endowed with capping ligands exhibit impressive optoelectronic properties and enable for cost-efficient solution processing and exciting application opportunities. We synthesize and characterize three different PeQDs with the same cubic CsPbBr3 core, but which are distinguished by the ligand composition and density. PeQD-1 features a binary didodecyldimethylammonium bromide (DDAB) and octanoic acid capping ligand system, with a high surface density of 1.53 nm−2, whereas PeQD-2 and PeQD-3 are coated by solely DDAB at a gradually lower surface density. We show that PeQD-1 endowed with highest ligand density features the highest dispersibility in toluene of 150 g/L, the highest photoluminescence quantum yield of 95% in dilute solution and 59% in a neat film, and the largest core-to-core spacing in neat thin films. We further establish that ions are released from the core of PeQD-1 when it is exposed to an electric field, although it comprises a dense coating of one capping ligand per four surface core atoms. We finally exploit these combined findings to the development of a light-emitting electrochemical cell (LEC), where the active layer is composed solely of solution-processed pure PeQDs, without additional electrolytes. In this device, the ion release is utilized as an advantage for the electrochemical doping process and efficient emissive operation of the LEC.

Hyaluronic Acid Aerogels Made Via Freeze-Thaw-Induced Gelation.

The biodegradability, biocompatibility, and bioactivity of hyaluronic acid (HA), a natural polysaccharide, combined with the low density, high porosity, and high specific surface area of aerogels attract interest for biomedical applications such as wound dressings. In this work, physically cross-linked HA aerogels were prepared via the freeze-thaw (FT) induced gelation method, solvent exchange, and drying with supercritical CO2. The morphology and properties of HA aerogels (volume shrinkage, density, and specific surface area) were investigated as a function of several process parameters: HA concentration, solution pH, number of FT cycles, and type of nonsolvent used during solvent exchange. We demonstrate that the HA solution pH plays a key role in the aerogel formation, as not all conditions result in materials with high specific surface area. HA aerogels were of low density (<0.2 g/cm3), high specific surface area (up to 600 m2/g), and high porosity (≥90%). Scanning electron microscopy pictures revealed that HA aerogels present a porous structure with meso- and small macropores. The results show that HA aerogels are promising biomaterials with tunable properties and internal structure that offer high potential as, e.g., wound dressings.

Study of monolithically integrated 940 nm AlGaAs distributed Bragg reflectors on graded GaAsP/bulk Si substrates

We report the fabrication of monolithically integrated 940 nm AlGaAs distributed Bragg reflectors (DBRs) on graded GaAsP/Si substrates. Low-density surface bumps and cross-hatch patterns were observed on the DBR surfaces. Cross-sectional DBR layers are smooth and flat. The reflectance spectra of the GaAsP/Si DBRs have lower intensities than those of the GaAs DBRs and have double peaks. Transfer matrix method calculations, surface scratch and polishing tests were conducted, which suggest that the surface cross-hatch was the cause of the inferior DBR reflectance spectra.

Novel techniques for characterising graphene nanoplatelets using Raman spectroscopy and machine learning

A significant challenge for graphene nanoplatelet (GNP) suppliers is the characterisation of platelet morphology in industrial environments. This challenge is further exacerbated to platelet surface chemistry when scalable functionalisation processes, such as plasma treatment, are used to modify the GNPs to improve the filler-matrix interphase in nanocomposites. The costly and complex suite of analytical equipment necessary for a complete material description makes quality control and process optimisation difficult. Raman spectroscopy is a facile and accessible characterisation technique, with recent advancements unlocking fast mapping for rapid data collection. In this study, we develop novel techniques to better characterise GNP morphology and changes in surface chemistry using Raman maps of bulk powders. Providing a bespoke algorithmic framework for the analysis of these advanced materials. An unsupervised peak fitting and processing algorithm was used to extract crystallinity data and correlate it with laser-diffraction-derived lateral size values for a commercial set of GNPs rapidly and accurately. Classical machine learning was used to identify the most informative Raman features for classifying the plasma-functionalised GNPs. The initial material properties were found to affect the peak features that were the most useful for classification. In low defect density and low specific surface area GNPs, the D peak full width at half maximum is found to be the most useful, whereas the ratio is the most useful in the opposite case. Finally, a convolutional neural network was trained to discern between different GNP grades with 86% accuracy. This work demonstrates how computer vision could be deployed for rapid and accurate quality control on the factory floor.

Photovoltaic Performance of Si and SiGe Surfaces Sonochemically Activated in Dichloromethane

Aims: To activate Si and SiGe surfaces by employing the sonochemical treatment at different operating frequencies in dichloromethane to improve the surface photovoltage signal. Background: To produce integrated electronic devices, one needs to achieve low surface and interface trap densities. In this respect, placing a passivating thin layer on Si and Ge surfaces, which saturates the electronic levels of traps and therefore affects the carrier recombination velocities at the surface, is of great interest. Objective: To demonstrate that the effectiveness of the treatment of Si and SiGe surfaces depends on the ultrasonic frequency used. Methods: Photovoltaic transients, electron microscopy, EDX spectroscopy. Result: The surface photovoltage (SPV) decay curves can be divided into rapid (τ_1) and slow (τ_2) components. The sonication effect on the SPV is different for the treatment done at about 25 and 400 kHz. The SPV signal in Si gradually increases with increasing lower-frequency sonication time, whereas the SPV enhancement on SiGe is somewhat smaller. Increasing the sonication time increases the amplitude of the τ_2 component in Si. In SiGe, the lower-frequency sonication quenches the τ_2 component yielding a nearly single-exponential decay form. This trend is even more pronounced at the higher-frequency sonication. Conclusion: The sonochemical treatments greatly intensify the formation of CxHy–Si and CxHy–Ge bonds on Si and Si1-xGex surfaces, resulting in increased SPV signals and prolonged SPV decay times. These results demonstrate that sonochemical treatment is a more effective technique to obtain stable highly passivated Si and Si1-xGex surfaces in comparison with wet chemical treatments in hydrocarbon solutions.

Hydrophobic and elastic silica-based aerogels with organic and inorganic in-situ hybrid structure for cryogenic insulation

Silica aerogels have potential to be used as alternatives in the cryogenic applications, but are still limited by the complex preparation process and high cost. In this work, a simple self-catalyzed gelling process and ambient drying method were utilized to prepare hydrophobic and low-density silica-based gels (HSAs) with organic and inorganic in-situ hybrid structure using methyltrimethoxysilane and bis[3-(triethoxysilyl)propyl]amine (BTPA) as precursors. The self-catalyzed gelling strategy is ascribed to the amine groups from BTPA. HSAs show a reversible deformation of 14 % and high failure strength up to 1.6 MPa even at the low temperature of −50 °C. Benefiting from the low density and high specific surface area, the thermal conductivity of the silica-based aerogels at −50 °C is as low as 21.8 mW·m−1·K−1. The HSAs are potential as ideal cryogenic insulation materials in a low-temperature and humid environment.

PHANGS–JWST First Results: Tracing the Diffuse Interstellar Medium with JWST Imaging of Polycyclic Aromatic Hydrocarbon Emission in Nearby Galaxies

JWST observations of polycyclic aromatic hydrocarbon (PAH) emission provide some of the deepest and highest resolution views of the cold interstellar medium (ISM) in nearby galaxies. If PAHs are well mixed with the atomic and molecular gas and illuminated by the average diffuse interstellar radiation field, PAH emission may provide an approximately linear, high-resolution, high-sensitivity tracer of diffuse gas surface density. We present a pilot study that explores using PAH emission in this way based on Mid-Infrared Instrument observations of IC 5332, NGC 628, NGC 1365, and NGC 7496 from the Physics at High Angular resolution in Nearby GalaxieS-JWST Treasury. Using scaling relationships calibrated in Leroy et al., scaled F1130W provides 10–40 pc resolution and 3σ sensitivity of Σgas ∼ 2 M ⊙ pc−2. We characterize the surface densities of structures seen at <7 M ⊙ pc−2 in our targets, where we expect the gas to be H i-dominated. We highlight the existence of filaments, interarm emission, and holes in the diffuse ISM at these low surface densities. Below ∼10 M ⊙ pc−2 for NGC 628, NGC 1365, and NGC 7496 the gas distribution shows a “Swiss cheese”-like topology due to holes and bubbles pervading the relatively smooth distribution of the diffuse ISM. Comparing to recent galaxy simulations, we observe similar topology for the low-surface-density gas, though with notable variations between simulations with different setups and resolution. Such a comparison of high-resolution, low-surface-density gas with simulations is not possible with existing atomic and molecular gas maps, highlighting the unique power of JWST maps of PAH emission.

Calibration of hybrid resolved star formation rate recipes based on PHANGS–MUSE Hα and Hβ maps

Mapping star-formation rates (SFR) within galaxies is key to unveiling their assembly and evolution. Calibrations exist for computing the SFR from a combination of ultraviolet and infrared bands for galaxies as integrated systems, but their applicability to sub-galactic (kiloparsec) scales remains largely untested. We used integral field spectroscopy of 19 nearby (D &lt; 20 Mpc) galaxies obtained by PHANGS–MUSE to derive accurate Balmer decrements (Hα/Hβ) and attenuation-corrected Hα maps. We combined this information with mid-infrared maps from WISE at 22 μm and ultraviolet maps from GALEX in the far-UV band to derive SFR surface densities in nearby galaxies on resolved (kiloparsec) scales. Using the Hα attenuation-corrected SFR as a reference, we find that hybrid recipes from the literature overestimate the SFR in regions of low SFR surface density, low specific star-formation rate (sSFR), low attenuation, and old stellar ages. We attribute these trends to heating of the dust by old stellar populations (IR cirrus). We calibrated this effect by proposing functional forms for the coefficients in front of the IR term that depend on band ratios sensitive to the sSFR. These recipes return SFR estimates that agree with those in the literature at high sSFR (log(sSFR/yr−1) &gt; − 9.9). Moreover, they lead to negligible bias and &lt; 0.16 dex scatter when compared to our reference attenuation-corrected SFR from Hα. These calibrations prove reliable as a function of physical scale. In particular, they agree within 10% with the attenuation corrections computed from the Balmer decrement on 100 pc scales. Despite small quantitative differences, our calibrations are also applicable to integrated galaxy scales probed by the MaNGA survey, but with a larger scatter (up to 0.22 dex). Observations with JWST open up the possibility to calibrate these relations in nearby galaxies with cloud-scale (∼100 pc) resolution mid-IR imaging.

Long-term Protoplanetary Disk Evolution from Molecular Cloud Core Collapse and Implications for Planet Formation. II. Strong Disk Self-gravity

We continue to investigate long-term protoplanetary disk evolution and focus on the situation of strong disk self-gravity (DSG). We call such a disk a type III disk. A large amount of mass is stored in the disk due to large angular momentum. When the disk becomes massive enough, a dense region (DR) is formed due to gravitational instability. This instability is triggered by the combined effect of radial gravitational attraction and a decrease in disk scale height. Viscosity cannot smooth out the DR due to strong DSG. We further investigate the subsequent disk evolution under the assumption of axisymmetry. Besides the viscous process, angular momentum flux caused by the perturbation of DSG also plays a role in the transport of angular momentum. The combination of the two processes results in the efficient transport of angular momentum in the outer disk and prevents the disk from becoming very massive. Due to the interaction between the DR and the inner disk, a gap between them is formed. This gives a nonplanetary origin of the gap. In ∼106 yr, a surface density plateau and a very low surface density region are formed in the inner disk. In a type III disk, there are several locations where the radial drift of solids can be stopped. Objects formed in the DR may remember some of the properties of the DR, such as large mass and large angular momentum. In particular, a planetary system with wide-orbit giant planets may be formed in the DR. Finally, it is still difficult to identify what type of disk the solar nebula belongs to.

Super-Aerophilic Biomimetic Cactus for Underwater Dispersed Microbubble Capture, Self-Transport, Coalescence, and Energy Harvesting.

Human ocean activities are inseparable from the supply of energy. The energy contained in the gas-phase components dispersed in seawater is a potential universal energy source for eupelagic or deep-sea equipment. However, the low energy density of bubbles dispersed in water introduces severe challenges to the potential energy harvesting of gas-phase components. Here, a super-aerophilic biomimetic cactus is developed for underwater dispersive microbubble capture and energy harvesting. The bubbles captured by the super-aerophilic biomimetic cactus spines, driven by the surface tension and liquid pressure, undergo automatic transport, coalescence, accumulation, and concentrated release. The formerly unavailable low-density dispersive surface free energy of the bubbles is converted into high-density concentrated gas buoyancy potential energy, thereby providing an energy source for underwater in situ electricity generation. Experiments show a continuous process of microbubble capture by the biomimetic cactus and demonstrate a 22.76-times increase in output power and a 3.56-times enhancement in electrical energy production compared with a conventional bubble energy harvesting device. The output energy density is 3.64 times that of the existing bubble energy generator. This work provides a novel approach for dispersive gas-phase potential energy harvesting in seawater, opening up promising prospects for wide-area in situ energy supply in underwaterenvironments.

On-Demand Cell Sheet Release with Low Density Peptide-Functionalized Non-LCST Polymer Brushes.

Cell sheet harvesting offers a great potential for the development of new therapies for regenerative medicine. For cells to adhere onto surfaces, proliferate, and to be released on demand, thermoresponsive polymeric coatings are generally considered to be required. Herein, an alternative approach for the cell sheet harvesting and rapid release on demand is reported, circumventing the use of thermoresponsive materials. This approach is based on the end-group biofunctionalization of non-thermoresponsive and antifouling poly(2-hydroxyethyl methacrylate) (p(HEMA)) brushes with cell-adhesive peptide motifs. While the nonfunctionalized p(HEMA) surfaces are cell-repellant, ligation of cell-signaling ligand enables extensive attachment and proliferation of NIH 3T3 fibroblasts until the formation of a confluent cell layer. Remarkably, the formed cell sheets can be released from the surfaces by gentle rinsing with cell-culture medium. The release of the cells is found to be facilitated by low surface density of cell-adhesive peptides, as confirmed by X-ray photoelectron spectroscopy. Additionally, the developed system affords possibility for repeated cell seeding, proliferation, and release on previously used substrates without any additional pretreatment steps. This new approach represents an alternative to thermally triggered cell-sheet harvesting platforms, offering possibility of capture and proliferation of various rare cell lines via appropriate selection of the cell-adhesive ligand.

TOI-1136 is a Young, Coplanar, Aligned Planetary System in a Pristine Resonant Chain

Convergent disk migration has long been suspected to be responsible for forming planetary systems with a chain of mean-motion resonances (MMRs). Dynamical evolution over time could disrupt the delicate resonant configuration. We present TOI-1136, a 700 ± 150 Myr old G star hosting at least six transiting planets between ∼2 and 5 R ⊕. The orbital period ratios deviate from exact commensurability by only 10−4, smaller than the ∼10−2 deviations seen in typical Kepler near-resonant systems. A transit-timing analysis measured the masses of the planets (3–8M ⊕) and demonstrated that the planets in TOI-1136 are in true resonances with librating resonant angles. Based on a Rossiter–McLaughlin measurement of planet d, the star’s rotation appears to be aligned with the planetary orbital planes. The well-aligned planetary system and the lack of a detected binary companion together suggest that TOI-1136's resonant chain formed in an isolated, quiescent disk with no stellar flyby, disk warp, or significant axial asymmetry. With period ratios near 3:2, 2:1, 3:2, 7:5, and 3:2, TOI-1136 is the first known resonant chain involving a second-order MMR (7:5) between two first-order MMRs. The formation of the delicate 7:5 resonance places strong constraints on the system’s migration history. Short-scale (starting from ∼0.1 au) Type-I migration with an inner disk edge is most consistent with the formation of TOI-1136. A low disk surface density (Σ1 au ≲ 103g cm−2; lower than the minimum-mass solar nebula) and the resultant slower migration rate likely facilitated the formation of the 7:5 second-order MMR.

Flexible, humidity- and contamination-resistant superhydrophobic MXene-based electrospun triboelectric nanogenerators for distributed energy harvesting applications.

The low surface-charge density, poor stability and irreparable surface of triboelectric materials under harsh environments are still some obstacles for developing high-performance triboelectric nanogenerators (TENGs). In particular, a two-dimensional MXene material's surface is likely to be corroded by water molecules under high humidity conditions owing to its hydrophilic nature, limiting the output performance and stability of TENGs. Herein, an approach for fabricating a humidity- and contamination-resistant MXene-based TENG is established using the electrospinning technique. First, nanofibrous layers of MXene/MoS2 composites blended in a cellulosic polymer matrix were prepared, benefitting the high surface roughness and controlled air-trapping pores. Furthermore, the prepared nanofibrous layers were chemically modified with stearic acid (SA), which enhances the hydrophobicity and electronegativity of MXene/MoS2 composites. In a typical synthesis, four different compositions of MXene/MoS2/cellulose acetate nanofibers were prepared, which illustrates that an increasing concentration of MoS2 could effectively tune the surface oxidation, hydrophilic nature, and surface roughness of MXene as well as induce a piezoelectricity-enhanced triboelectric potential. On the other side, the SA modification ultimately generated a superhydrophobic surface with low surface energy and a high water contact angle of ∼154°. The integrated TENG displayed an enhanced output voltage of ∼140 V and an instantaneous power density of ∼2975 mW cm-2 with long-term stability under high humidity conditions. Additionally, the self-cleaning properties were demonstrated, ensuring the sustainability and reusability of the TENG in a contaminated environment. Moreover, the fabricated MXene-based superhydrophobic layer can harvest the energy on dripping water droplets based on the liquid-solid contact-electrification TENG mode. Overall, this work paves the way for the design and development of humidity- and contamination-resistant triboelectric materials and guides the study of harvesting of distributed environmental energy efficiently.

3D flower-shape Co/Cu bimetallic nanocomposites with excellent wideband electromagnetic microwave absorption

Electromagnetic wave (EMW) absorbing materials prepared by Metal-organic-frameworks (MOFs) derived two-dimensional sheet carbon materials and magnetic metal composites have been widely studied because of their advantages of low density and large specific surface area. However, it is still a challenge to design the microstructure and composition of materials effectively to obtain the best EMW absorption properties. In this work, 3D flower-shape Co/Cu bimetallic nanocomposites were synthesized by calcination of MOFs precursors. By tuning the ratio of Co and Cu salts, nanocomposites with different morphology, size and pore structure were obtained. Impedance matching can be improved by adjusting the synergistic effect of magnetic loss and dielectric loss. When the molar ratio of Co and Cu salts was 4:1, the best EMW absorption performance of the CoCu-CNF-10 composite was achieved. The minimum reflection loss reaches − 51.7 dB at 12.6 GHz with a thin thickness of 2.7 mm, while the effective absorption bandwidth is as broad as 6.4 GHz (9.7–16.1 GHz). This work provides a new idea for the rational design of MOFs-derived materials with excellent EMW absorption properties.

Strength studies on concrete containing of recycled coarse aggregate and granite cutting waste as partial replacement of fine aggregate

Recycled coarse aggregates and natural coarse aggregates have characteristic structures, such as porosity, water absorption, low surface density, and crush value, approving to the studies presented. Selecting suitable raw materials based on concrete's particular show standards, later designing cost-effective, high-quality concrete utilizing mixed proportion methods, is the utmost method to overcome the limitations of design methods, and this presents fresh concepts and design methods. The recycled coarse aggregates and natural coarse aggregate surround characteristics, including porosity, water absorption, low surface density, and greater crush value per the research studies. This research works investigates the compressive strength, split tensile strength, and flexural strength of concrete specimens. The natural coarse aggregates have been substituted with 0 percent, 20 percent, 40 percent, 60 percent, 80 percent, and 100 percent by a recycled coarse aggregate of construction & demolition waste of 30-years-old building and fine aggregate has been substituted with 40 percent of granite cutting waste. In this research work, the strength of the recycled coarse aggregates and granite cutting waste concrete was calculated. This research work presents the associate of the outcomes of the recycled coarse aggregates and granite cutting waste base concrete with the physical and mechanical properties of concrete.

Cellulose Source Tailors the Physical and Structural Properties of Double-Functionalized Aerogels

ABSTRACT Cellulose aerogels are solid materials with high porosity, low density, and large surface area, and show excellent absorption of mechanical stress. These characteristics are appropriate for the development of new high-value products. However, over the years, it has been increasingly difficult to compare different studies about this material due to the different approaches used. In the present work, three different raw materials, bacterial cellulose from synthetic medium (BC), bacterial cellulose from cashew juice permeate (BCP), and eucalyptus nanocellulose (EC) were double-functionalized with TEMPO oxidation followed by silanization and freeze-dried, resulting in three different types of cellulose aerogels. These aerogels were evaluated for their performance in the absorption of organic oils/solvents and mechanical properties. The raw materials lead to aerogels with different characteristics. BC aerogel has the best mechanical properties and absorption capacity after 7 cycles; BCP aerogel presented the highest values for oil absorption and EC aerogel for organic solvent absorption.

A Multifunctional Flexible Electronic Skin for Dynamic Thermal Radiation Regulation and Electromagnetic Interference Shielding.

A multifunctional electronic skin with thermal radiation regulation and electromagnetic interference (EMI) shielding is urgent for electronic systems because of the thermal radiation emission and electromagnetic wave pollution. Herein, a flexible electronic skin was designed and fabricated, where the polyaniline (PANI) served as the functional layer and Ti3C2Tx MXene was employed as the conductive electrode. The transformation of emeraldine salt (ES) and leucoemeraldine base (LB) of PANI makes the skin achieve an infrared emissivity modulation, and the electromagnetic loss of PANI and ultrahigh electrical conductivity of Ti3C2Tx MXene make it exhibit EMI shielding ability. Benefiting from the special structural design, the multifunctional skin with a small thickness (0.3 mm) and low surface density (0.06 g/cm2) exhibits an excellent infrared emissivity modulation ability (Δε) of 0.32 with emissive power of 119.1 W/m2 at the wavelength range of 2.5-25 μm and total shielding effectiveness (SET) of 36.3 dB over the X-band (8.2-12.4 GHz). Meanwhile, the multifunctional skin remains black in the visible spectrum but a changeable color in the infrared spectrum. Even after repeated bending and twisting, the multifunctional skin still maintains a good emissivity adjustment. The simultaneous realization of dynamic thermal radiation regulation and EMI shielding endows the skin promising potential for various fields, such as adaptive infrared camouflage, thermal regulation, anticounterfeiting, and EMI shielding-related crossing field.

Robust Carbonaceous Nanofiber Aerogels from All Biomass Precursors

AbstractAerogels, a type of fascinating material with very low density and high surface area, show many unique properties and unlimited applications. To boost their practical applications, it is necessary to develop efficient, controllable, and low‐cost methods to produce high‐performance aerogels on a large‐scale, preferably in a sustainable way. Here, a general strategy is reported for controllable fabrication of a family of carbonaceous nanofiber aerogels (CNFAs) by biomass‐derived nanofibers template‐directed hydrothermal carbonization method. Abundant functional groups are exposed on the surface of the prepared carbonaceous nanofibers. Importantly, in contrast to traditional nature biopolymer‐based aerogels, a superior combination of good recoverability and high strength is achieved for the CNFAs by adjusting the synthetic parameters. The successful synthesis of such fascinating materials provides an excellent platform for design and construction of devices for fast water treatment. The synthetic strategy and sustainable concept presented in this work will open a new way to prepare advanced aerogels with unique properties for wide applications.

Ultra-diffuse Galaxies as Extreme Star-forming Environments. II. Star Formation and Pressure Balance in H i-rich UDGs

In addition to occupying the extreme, diffuse tail of the dwarf galaxy population, ultra-diffuse galaxies (UDGs) are themselves a key laboratory in which to study star formation in extreme low-density environments. In the second paper of this series, we compare the spatially resolved star formation activity of 22 H i-selected UDGs and 21 “normal” dwarf galaxies within 120 Mpc to predictions within the pressure-regulated, feedback-modulated (PRFM) theory of star formation. To do so, we employ a joint spectral energy distribution fitting method that allows us to estimate star formation rate and stellar mass surface density from UV-optical imaging. We find that the PRFM framework extends successfully to the UDG regime—although the UDGs in our sample show unusually low star formation rate surface densities given their H i content, this low star formation efficiency can be naturally explained by the diffuse structure of the UDGs. In fact, when cast in the PRFM framework, the relationship between midplane pressure and star formation in the UDG sample is in good agreement not only with the “normal” dwarf reference sample, but also with measurements from more massive galaxies. Our results suggest that despite their low star formation efficiencies, the H i-rich UDGs need not be forming stars in an exotic manner. We also find that the UDGs are likely H2 poor compared even to the overall dwarf population.