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Quercus alba L., also known as white oak, eastern white oak, or American white oak, is a quintessential North American species within the white oak section (Quercus) of the genus Quercus, subgenus Quercus. This species plays a vital role as a keystone species in eastern North American forests and plays a significant role in local and regional economies. As a long-lived woody perennial covering an extensive natural range, Q. alba’s biology is shaped by a myriad of adaptations accumulated throughout its natural history. Populations of Q. alba are crucial repositories of genetic, genomic, and evolutionary insights, capturing the essence of successful historical adaptations and ongoing responses to contemporary environmental challenges in the Anthropocene. This intersection offers an exceptional opportunity to integrate genomic knowledge with the discovery of climate-relevant traits, advancing tree improvement, forest ecology, and forest management strategies. This review provides a comprehensive examination of the current understanding of Q. alba’s biology, considering past, present, and future research perspectives. It encompasses aspects such as distribution, phylogeny, population structure, key adaptive traits to cyclical environmental conditions (including water use, reproduction, propagation, and growth), as well as the species’ resilience to biotic and abiotic stressors. Additionally, this review highlights the state-of-the-art research resources available for the Quercus genus, including Q. alba, showcasing developments in genetics, genomics, biotechnology, and phenomics tools. This overview lays the groundwork for exploring and elucidating the principles of longevity in plants, positioning Q. alba as an emerging model tree species, ideally suited for investigating the biology of climate-relevant traits.

 

Eastern black walnut (Juglans nigraL.), one of the most valuable timber and veneer trees in North America, provides nut shells with unique industrial uses and nut kernels with distinctive culinary attributes. A mature F₁full-sib progeny orchard of 248 individuals from the cross of two eastern black walnut cultivars provides a long-term resource for discovering genetic mechanisms controlling life history, quality traits, and stress resistance. The genetic linkage map, constructed with 356 single nucleotide polymorphism (SNP) markers and 62 expressed sequence tag simple sequence repeats (EST-SSRs), is 1645.7 cM in length, distributed across the expected 16 linkage groups. In this first application of QTL mapping inJ. nigra, we report QTL for budbreak, peak pistillate bloom, peak staminate bloom, and heterodichogamy. A dominant major QTL for heterodichogamy is reported, the sequence for which is syntenic with the heterodichogamy QTL on chromosome 11 of Persian walnut (J. regiaL.). The mapping population parents are both protogynous, and segregation suggests a Mendelian component, with a 3:1-like inheritance pattern from heterozygous parents. Mapping the sequenced EST-SSR markers to theJ. regia“Chandler” V2.0 genome sequence revealed evidence for collinearity and structural changes on two of the sixteen chromosomes. The inclusion of sequenced EST-SSR markers enables the direct comparison of this and subsequentJ. nigramaps and otherJuglandaceaegenetic maps. This investigation initiates long-term QTL detection studies for quality and stress resistance traits in black walnut.

 

A wafer-scale CMOS-compatible process for heterogeneous integration of III-V epitaxial material onto silicon for photonic device fabrication is presented. Transfer of AlGaAs-GaAs Vertical-Cavity Surface-Emitting Laser (VCSEL) epitaxial material onto silicon using a carrier wafer process and metallic bonding is used to form III-V islands which are subsequently processed into VCSELs. The transfer process begins with the bonding of III-V wafer pieces epitaxy-down on a carrier wafer using a temporary bonding material. Following substrate removal, precisely-located islands of material are formed using photolithography and dry etching. These islands are bonded onto a silicon host wafer using a thin-film non-gold metal bonding process and the transfer wafer is removed. Following the bonding of the epitaxial islands onto the silicon wafer, standard processing methods are used to form VCSELs with non-gold contacts. The removal of the GaAs substrate prior to bonding provides an improved thermal pathway which leads to a reduction in wavelength shift with output power under continuous-wave (CW) excitation. Unlike prior work in which fullyfabricated VCSELs are flip-chip bonded to silicon, all photonic device processing takes place after the epitaxial transfer process. The electrical and optical performance of heterogeneously integrated 850nm GaAs VCSELs on silicon is compared to their as-grown counterparts. The demonstrated method creates the potential for the integration of III-V photonic devices with silicon CMOS, including CMOS imaging arrays. Such devices could have use in applications ranging from 3D imaging to LiDAR. 

Enhancing the functionality of silicon through the integration of other materials such as III-V semiconductors has been recognized as a path to overcoming limitations imposed by characteristics fundamental to silicon's material physics while still capitalizing on properties that have enabled the success of the global integrated circuit industry [1]–[2][3]. High-speed electronic devices, devices with high breakdown voltages, light emitting/detecting devices, and devices for photon control can all be integrated with conventional CMOS to perform specialized electronic or photonic functions if suitable methods for forming such heterogeneously integrated regions are available that provide high yield and are compatible with fabrication processes that occur subsequent to the heterogeneous integration process. Technical challenges include lattice mismatch, thermal expansion coefficient differences, having the capability to form low-resistance electrical contacts using materials that are compatible with CMOS, more generally managing cross-contamination in tools used for front-end-of-line processing after III-V regions are established on the silicon wafers, and thermal management for the heterogeneously integrated devices or circuits. These together create formidable obstacles, but there is also the obstacle of defining a business case for creating hybrid wafer fabs given the applications that would be served by ICs with enhanced functionality. Bringing functions that are off chip onto the chip needs to be justified both technically and financially. 

An array of active photonic devices is fabricated in unison after a heterogeneous integration process first metal-eutectically bonds these distinct materials as a distribution onto a silicon host wafer. The patterning out of heterogeneous materials followed by the formation of all photonic devices allows for wide-area fine-alignment without the need for discrete die alignment or placement. The integration process is designed as a CMOS-compatible, scalable method for bringing together distinct III-V epitaxial structures and optical-waveguiding epitaxial structures, demonstrating the capabilities of forming a multi-chip layer of photonic materials. Integrated GaAs-based vertical light-emitting transistors (LET) are designed and fabricated as the active devices whose third electrical terminal provides an electrical interconnect and thermal dissipation path to the silicon host wafer. The performance of these devices as both electrical transistors and spontaneous-emission optical devices is compared to their monolithically-integrated counterparts to investigate improvements in device characteristics when integrated onto silicon. The fabrication methods are modified and optimized for thin-film transferred materials and are then extended to transistor laser (TL) fabrication. Passive waveguiding structures are designed and simulated for coupling light from the active devices, and their fabrication scheme is presented such that it can be similarly performed with transferred materials. Work toward the demonstration of integrated transistor lasers is shown to represent progress toward an electronic-photonic circuit network. The combination of heterogeneous integration with three-terminal photonic structures enables an elegant solution to both packaging and signal interconnect constraints for the implementation of photonic logic in silicon photonics systems. 

An array of heterogeneously integrated light-emitting transistors is fabricated after an epitaxial transfer process bonds and interconnects active III-V photonic material onto a CMOS- compatible host wafer for the purposes of establishing a photonic logic network. 

The recent development of 8-in Gallium Nitride on Silicon (GaN-on-Si) wafers has facilitated cost effective, large-scale manufacturability of GaN-based electronics. Leveraging its wide band gap, capability to support a two dimensional electron gas (2DEG) layer, and strong built-in polarization effects, GaN-based electronic devices have become a viable cost-effective successor to silicon-based devices for high-performance applications where the large bandgap and high breakdown field are required. The advantageous properties of GaN-on-Si material, however, have yet to be utilized for photonic integrated circuit applications. Therefore, the exploration of GaN for efficient on-chip optical modulation and switching applications is examined. In order to effectively characterize GaN’s capabilities for optical modulation and switching, GaN based Mach-Zehnder modulators are designed and fabricated. Through simulating the propagating optical modes supported in a GaN-based Mach-Zehnder structure, the geometry of the device is designed to optimize optical modal overlap with the 2DEG layer while maintaining single-mode performance. Through electrical and optical characterization, the effective electro-optic coefficient and Vπ length are measured. These measurements provide a method of benchmarking GaN-based photonic devices for their optical modulation and switching efficiency. 

The recent development of 8-in Gallium Nitride on Silicon (GaN-on-Si) wafers has facilitated cost effective, large-scale manufacturability of GaN-based electronics. Leveraging its wide band gap, capability to support a two dimensional electron gas (2DEG) layer, and strong built-in polarization effects, GaN-based electronic devices have become a viable cost-effective successor to silicon-based devices for high-performance applications where the large bandgap and high breakdown field are required. The advantageous properties of GaN-on-Si material, however, have yet to be utilized for photonic integrated circuit applications. Therefore, the exploration of GaN for efficient on-chip optical modulation and switching applications is examined. In order to effectively characterize GaN’s capabilities for optical modulation and switching, GaN-based Mach-Zehnder modulators are designed and fabricated. Through simulating the propagating optical modes supported in a GaN-based Mach-Zehnder structure, the geometry of the device is designed to optimize optical modal overlap with the 2DEG layer while maintaining single-mode performance. Through electrical and optical characterization, the effective electro-optic coefficient and Vπ length are measured. These measurements provide a method of benchmarking GaN-based photonic devices for their optical modulation and switching efficiency. 

The Fusarium solani species complex (FSSC) is a clade of environmentally ubiquitous fungi that includes plant, animal, and insect associates. Here, we report the draft genome sequence of the undescribed species FSSC 6 (isolate MYA-4552), housed in the gut of the wood-boring cerambycid beetle Anoplophora glabripennis .