The size dependence of the electronic spectrum of InAs nanocrystals ranging in radius from 10–35 Å has been studied by size-selective spectroscopy. An eight-band effective mass theory of the quantum size levels has been developed which describes the observed absorption level structure and transition intensities very well down to smallest crystal size using bulk band parameters. This model generalizes the six-band model which works well in CdSe nanocrystals and should adequately describe most direct semiconductor nanocrystals with band edge at the Γ-point of the Brillouin zone.

Productivity throughout the North American Great Plains grasslands is generally considered to be water limited, with the strength of this limitation increasing as precipitation decreases. We hypothesize that cumulative actual evapotranspiration water loss (AET) from April to July is the precipitation-related variable most correlated to aboveground net primary production (ANPP) in the U.S. Great Plains (GP). We tested this by evaluating the relationship of ANPP to AET, precipitation, and plant transpiration (Tr). We used multi-year ANPP data from five sites ranging from semiarid grasslands in Colorado and Wyoming to mesic grasslands in Nebraska and Kansas, mean annual NRCS ANPP, and satellite-derived normalized difference vegetation index (NDVI) data. Results from the five sites showed that cumulative April-to-July AET, precipitation, and Tr were well correlated (R2: 0.54–0.70) to annual changes in ANPP for all but the wettest site. AET and Tr were better correlated to annual changes in ANPP compared to precipitation for the drier sites, and precipitation in August and September had little impact on productivity in drier sites. April-to-July cumulative precipitation was best correlated (R2 = 0.63) with interannual variability in ANPP in the most mesic site, while AET and Tr were poorly correlated with ANPP at this site. Cumulative growing season (May-to-September) NDVI (iNDVI) was strongly correlated with annual ANPP at the five sites (R2 = 0.90). Using iNDVI as a surrogate for ANPP, we found that county-level cumulative April–July AET was more strongly correlated to ANPP than precipitation for more than 80% of the GP counties, with precipitation tending to perform better in the eastern more mesic portion of the GP. Including the ratio of AET to potential evapotranspiration (PET) improved the correlation of AET to both iNDVI and mean county-level NRCS ANPP. Accounting for how different precipitation-related variables control ANPP (AET in drier portion, precipitation in wetter portion) provides opportunity to develop spatially explicit forecasting of ANPP across the GP for enhancing decision-making by land managers and use of grassland ANPP for biofuels.

Colloidal nanocrystal/DNA conjugates hold the promise of becoming powerful probes for biological diagnostics as well as versatile building blocks for nanotechnology. To fully realize this potential, it is important to precisely control the number of oligonucleotides bound to the nanocrystal. Here we demonstrate electrophoretic isolation of 5 and 10 nm gold nanocrystals bearing discrete numbers of single-stranded DNA (1−5). The potential use of these discrete conjugates in the fabrication of novel nanostructures is discussed.

Viruses are obligate symbionts of cellular life forms that can replicate only within host cells and typically form virions (virus particles) to spread among host organisms. Virions numerically dominate the biosphere, exceeding the number of cells several-fold, and also comprise the main reservoir of genetic diversity on earth. Nearly all organisms host multiple, diverse viruses. Unlike cellular organisms, viruses have genomes (genetic information carriers incorporated into virions) that consist of all forms of RNA and DNA, suggesting an evolutionary connection between extant viruses and the primordial replicator pool. Lately, extensive mining of metagenomes and metatranscriptomes has dramatically expanded the world of viruses (virosphere), revealing an unsuspected and unprecedented diversity. Viruses share no universal genes and have multiple origins. However, about 15 viral hallmark genes each bring together multiple, diverse groups of viruses, and many other genes are shared within such groups. Evolution of viruses is inextricably intertwined with the evolution of their hosts. A key aspect of virus-host coevolution is the arms race resulting in accelerated evolution on both sides, especially of host defenses and viral counter-defenses. A complementary, prominent feature of this coevolution is exaptation, whereby viral genes are coopted by the hosts for antiviral defense and other roles, and conversely, viruses capture host genes for diverse functions in virus replication, virion morphogenesis and virus-host interaction. In this review, we attempt a synthesis of the current understanding of the global organization of the virosphere, the major trends and events in the evolution of viruses, and the high-level taxonomy of viruses.

Spezifische, unregelmäßige Anordnungen von Gold-Nanokristallen mit Durchmessern von 5 und 10 nm lassen sich gezielt mit Hilfe doppelsträngiger DNA als Templat herstellen (siehe Bild; A′ und B′ bezeichnen die zu den Sequenzen A bzw. B komplementären Oligonucleotidsequenzen). Die hier beschriebenen Methoden sollten sich auf Nanokristalle aus den verschiedensten Materialien anwenden lassen.

Summary form only given.Nanometer size crystals of inorganic semiconductors display a wealth of size dependent optical and electrical characteristics. Such nanocrystals (CdS, CdSe, InP, InAs), with well controlled interfaces, can now be fabricated by colloidal chemistry techniques. The resulting particles are extremely flexible chemically. Examples where nanocrystals have been incorporated into LEDs, photovoltaics, transistors, and on cell surfaces are described.

At least one large-body (diameter > 1.1 km) hypervelocity cratering event occurred during ~ 0.8-0.90 Ma (Zhamanshin, Kazakhstan) in the Middle Pleistocene Transition period. Analysis designed to reduce uncertainty in the dimensions of the Zhamanshin structure employing high resolution topography demonstrated that it likely generated a ~ 26.5 km diameter multi-ring crater. This is at least two times larger than the current best estimates. Using a range of accepted impactor sizes, velocities, compositions, and angles of impact, such impacts typically yield kinetic energies of impact over 240,000 Megatons (TNT). Explosive energetic events of this magnitude (e.g., Yellowstone Caldera) at other times (K-Pg) have created global environmental effects. The factor of two discrepancy in the dimensions of Zhamanshin increases the kinetic energy yield by factors of 7-10, with significantly larger environmental consequences. This justifies examination of rapid climate transitions linked to biological consequences, including those related to environmental perturbations, at ~0.9 Ma.

Research capabilities in nanoscience, molecular biology and computation have advanced to the point where it is possible to define research activities in which the development of nano-bio systems will support major DOE science goals. Specifically, we identify two major long term research goals which can motivate research at the intersection of nanoscience and biology: 1) Development of biological-systems-control for bioremediation, carbon dioxide sequestration and tailored biomaterials fabrication. 2) Development of artificial nanosystems with biomimetic functionality but without biological fragility. Basic research in support of these goals can be focused by identifying immediate research challenges involving the integration of physical nanostructures and biological nanostructures (i.e. proteins, with a strong emphasis on membrane-bound proteins) in a program of closely correlated theoretical and experimental research.

We have demonstrated that seeded growth of nanocrystals offers a convenient way to design nanoheterostructures with complex shapes and\nmorphologies by changing the crystalline structure of the seed. By using CdSe nanocrystals with wurtzite and zinc blende structure as seeds\nfor growth of CdS nanorods, we synthesized CdSe/CdS heterostructure nanorods and nanotetrapods, respectively. Both of these structures\nshowed excellent luminescent properties, combining high photoluminescence efficiency (∼80 and ∼50% for nanorods and nanotetrapods,\ncorrespondingly), giant extinction coefficients (∼2 × 10<sup>7</sup> and ∼1.5 × 10<sup>8</sup> M<sup>-1</sup> cm<sup>-1</sup> at 350 nm for nanorods and nanotetrapods, correspondingly),\nand efficient energy transfer from the CdS arms into the emitting CdSe core.

Recently, a tRNATrpCCA with a 4-base-pair (bp) anticodon stem (AS) was shown to efficiently recognize a near-cognate UGA codon in unicellular eukaryotes, such as some trypanosomatids and ciliates, thereby representing a novel codon reassignment mechanism. To determine whether this mechanism also evolved in bacteria, we analysed a dataset of 42 109 genomes, including previously reported cases of stop-to-tryptophan UGA reassignment and a newly identified instance in the phylum Patescibacteriota. We show that the 4-bp AS tRNATrp species are present across diverse bacteria and in some cases likely function in decoding in-frame UGA codons. Most notable is the endosymbiotic bacterium Candidatus Zinderia insecticola, which contains only the near-cognate 4-bp AS tRNATrpCCA, while lacking both canonical 5-bp AS tRNATrpCCA and a tRNATrpUCA. The secondary structure of this 4-bp AS tRNATrp resembles that of its eukaryotic counterpart, suggesting convergent evolution. We experimentally confirmed the UGA readthrough capacity of 4-bp AS tRNATrpCCA in Escherichia coli, and applied molecular dynamics simulations to suggest the underlying mechanism. Furthermore, we tested several predictions based on accepting the previously excluded possibility of C:A base pairing at the 3rd codon position. These findings provide new insights into the structural diversity of transfer RNAs (tRNAs) and expand our understanding of genetic code evolution.

This work presents a mechanistic modeling approach for simulating methane emissions from tri-ethylene glycol (TEG) dehydrators used in oil & gas (O&G) operations. The model was developed as a modular component of the Mechanistic Air Emissions Simulator (MAES) tool, incorporating species-specific absorption and emission dynamics through two-level, second-order polynomial regression (PR) models trained on ProMax simulation data: (1) species-level regression models that track the transfer rates of individual gas species within the dehydrator unit streams, and (2) outlet flow stream regression models that predict the fraction of inlet gas distributed among the outlet streams of the dehydrator unit. These behaviors were characterized over a range of glycol circulation ratios, wet gas pressures, and temperatures. The model was validated using root mean square error (RMSE) analysis. The species-level PR achieved low root mean square error (RMSE) values (< 0.03) for light hydrocarbon species across all dehydrator components, ranging from 0.0009 for methane to 0.029 for normal pentane. Similarly, the outlet-level PR yielded RMSE values below 0.002 for the dry gas fraction, 0.001 for the flash tank fraction, and 0.002 for the still vent fraction, demonstrating strong agreement between predicted and reference ProMax values. When deployed at field facilities, the model significantly improved MAES-simulated dehydrator emissions, revealing that gas-assisted glycol pump emissions are the dominant contributors to both dehydrator-level and site-level methane emissions under uncontrolled conditions. Further analysis of the 154 dehydrator units reported by operators under the AMI 2024 project showed that 54 units (31%) used gas-driven glycol pumps, of which 6 units (11%) operated with uncontrolled flash tanks, and 22 units (40.7%) were identified as potentially oversized. Of the six dehydrator units with uncontrolled gas-assisted pumps, pump emissions accounted for 90.25% of total dehydrator emissions and 63.10% of total site-level emissions. These findings highlight substantial opportunities for emissions mitigation through equipment upgrades.

Microneedle‐based access to plant phloem enables sustainable energy harvesting and in situ biochemical sensing, but its performance is limited by defense responses such as callose deposition triggered by mechanical overstimulation of cell walls. This study presents a combined numerical–experimental framework for investigation how microneedle penetration dynamics influence transient stress fields within plant cellular tissue. A 3D finite element model of tomato stem tissue was reconstructed from SEM data, incorporating elastic–plastic cell walls, compressible intracellular fluid, and an augmented‐Lagrangian contact to simulate cell‐wall rupture and middle‐lamella delamination. Simulations reveal that lower insertion velocities significantly reduce stress transients and localize stress propagation, favoring single‐cell failure over multicell delamination. This effect results from a reduced rate of energy transfer into the tissue during insertion, limiting elastic energy accumulation and mechanical loading of mechanosensory pathways associated with callose secretion. Microneedle prototypes were fabricated and tested on tomato stems. Despite the quasistatic experimental velocities, displacement‐based comparison showed good agreement with numerical predictions. Both approaches confirmed that slower penetration shifts energy partitioning toward elastic storage and rheological dissipation. Overall, the developed mesoscale FEM framework reliably captures microneedle–tissue interactions and provides a transferable tool for optimizing minimally disruptive microneedle insertion strategies.

OBJECTIVES: To assess the construct validity of a modified single-item measure of bother due to side effects (the GP5 item) from the Functional Assessment of Chronic Illness Therapy (FACIT) system by comparing it to current symptomatic side effects from the Patient-Reported Outcomes of the Common Terminology Criteria for Adverse Events (PROCTCAE) reported by patients with rheumatoid arthritis (RA). METHODS: Through a cross-sectional, web-based survey we collected information on the frequency of symptomatic side effects and bother from side effects related to RA medications. We applied multiple correspondence analysis (MCA) to reduce 80 symptomatic side effects into key dimensions (≥5% of the total variance each). We then examined associations among key dimensions, individual items, the sum of current side effects, and the single-item bother measure using Spearman rho. RESULTS: A total of 560 patients participated in the online survey. Our scree plot showed a clear elbow point after the first dimension, indicating that keeping just one dimension captured the most meaningful information. This overall side effect burden score appeared to reflect a broad concept influenced by a variety of symptomatic side effects, each having only a negligible to weak impact. CONCLUSIONS: Our results may indicate that individuals have diverse experiences of side effects, allowing the global index to capture these variations, even when they differ across patients. Thus, a single-item burden measure to side effects can potentially serve as a useful summary indicator, shedding light on the impact of symptomatic side effects experienced by RA patients.

Methane emissions from end-use installations in residential natural gas systems remain poorly quantified, despite their importance to both safety and climate policies worldwide. While distribution networks and appliances have received research attention, interior piping between the meter and appliances represents a critical knowledge gap. To address this gap, a systematic survey of 473 residential systems in Saarlouis, Germany, was conducted using standardized pressure decay tests (DVGW G 600). Measurements were performed during the installation of gas regulators necessitated by a grid pressure increase from 23 mbar to 55 mbar above ambient. This provided a unique opportunity to assess whole-system leakage under controlled conditions without installation modifications. Leak rates were standardized to reference pressure and converted to methane emissions using measured gas composition, using a linear pressure scaling as a provisional approximation valid for the small pressure differences in the applied test conditions. A total of 411 (86.9%) installations showed no detectable leak rate (LDL: 0.2 Lh−1). However, seven systems (1.5%) exceeded 1 Lh−1, and one surpassed the unacceptable threshold of 5 Lh−1. Mean emissions across all systems were 0.067 [0.041, 0.098] gh−1, with smaller installations showing higher volume-normalized rates. Critically, fewer than 1.48% of systems contributed more than 46% of total emissions, demonstrating a strongly skewed, heavy-tailed distribution. Scaled nationally using Monte Carlo methods accounting for sampling uncertainty and skewed distributions, residential interior piping contributes 12.30 [8.11, 18.55] Ggyear−1 to Germany’s methane emissions. These results emphasize the need to include residential leak rates in emission inventories and highlight the efficiency potential of targeted mitigation strategies focused on high-emitting installations under evolving EU methane regulations.

From the contents: Growth of Nanocrystals.- Energy States.- Dielectric Effects.- Mechanisms of Dephasing.- Trap Processes.- Effects of Static External Fields.- Nanocrystals of III-V Compounds.- Nanocrystals of Indirect-Gap Materials Concepts of Applications.