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1. Minority Student Preparation for STEM PhD Study: Impact of NSF Bridge to the Doctorate Programming

   https://doi.org/10.46328/ijtes.v4i3.122  

   Preuss, Michael D.; Merriweather, Samuel P.; Walton, Shannon D.; Butler-Purry, Karen L. (June 2020, International Journal of Technology in Education and Science)

   The Texas A&M University System (TAMUS) received funding from the National Science Foundation (NSF) for a Louis Stokes Alliance for Minority Participation (LSAMP) project in 1991 as one of the six initial awardees. As part of these efforts and upon reaching eligibility, the TAMUS LSAMP applied for and received additional funding to support a Bridge to the Doctorate (BTD) program. BTD programming provides financial, educational, and social support to incoming STEM master’s degree and PhD students for the first two years of their graduate study. BTD cohorts consist of up to 12 fellows who participate in a program of academic and professional development seminars and workshops. In project evaluation, annual interviews were conducted with the TAMUS BTD participants, the vast majority of whom were underrepresented minorities (92%). During the interviews, the BTD students were asked to discuss ten topics some of which addressed concerns specific to the implementation of the BTD project. This report considers answers provided in the five topic areas which have broader applicability: 1) the learning achieved by participants through participation in BTD, 2) the personal impact of participation in BTD, 3) the influence of BTD on informants’ educational goals, 4) the influence of BTD on informants’ career goals, and 5) barriers the BTD participants perceived to pursuing a PhD. Eighty project participants responded to the questions between 2009 and 2018. They were from eight distinct cohorts of BTD students and represented 32 different areas of STEM specialization. Qualitative analysis of their responses confirmed that students perceived the elements of the TAMUS BTD project to be efficacious and that there was a set of nine seminars from which participants consistently reported benefit. Additional findings were eight key areas in which learning was reported by participants, four areas in which the programming  had personal impact, five influences on educational goals,  nine impacts on career goals, and a detailed list of barriers graduate students who are underrepresented minorities (URM) perceive to pursuing a doctoral degree. The proven and easily replicated pattern of support programming, the demonstrated results of this programming, and insight into barriers URMs perceive to pursuing a STEM doctorate are immediately applicable to URM graduate student support at many institutions of higher education. 

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2. Charge-Transfer-Driven Electrical Conductivity in Single Crystals of Assembled Triphenylamine Bis-urea Macrocycles

   https://doi.org/10.1021/acs.jpcc.5c04522  

   Gbadamosi, Fahidat A; Islam, Md Faizul; Shaker, Abdulla E; Wijesekera, Gamage_Isuri P; Smith, Mark D; Winfred, J_S_Raaj Vellore; Wetthasinghe, Shehani T; Garashchuk, Sophya; Greytak, Andrew B; Shimizu, Linda S (August 2025, The Journal of Physical Chemistry C)

   Achieving tunable electrical conductivity in organic materials is a key challenge for the development of next-generation semiconductors. This study demonstrates a novel approach using triphenylamine (TPA) bis-urea macrocycles as supramolecular hosts for guest-induced modulation of charge-transfer (CT) properties. By encapsulating guests with varying reduction potentials, including 2,5-dichloro-1,4-benzoquinone (ClBQ), 2,1,3-benzothiadiazole (BTD), and malononitrile (MN), we observed significant changes in the electrical conductivity. Crystals of the 1(ClBQ)0.31 complex exhibited an electrical conductivity of ∼2.08 × 10–5 S cm–1, a 10,000-fold enhancement compared to the pristine host. This is attributed to efficient CT observed in spectroscopic analyses and is consistent with the computed small HOMO–LUMO gap (2.92 eV) in a model of the host–guest system. 1(MN)0.39 and 1(BTD)0.5 demonstrated moderate conductivities explained by the interplay of electronic coupling, reorganization energy, and energy gap. Lower ratios of guest inclusion decreased the electrical conductivity by 10-fold in 1(ClBQ)0.18, while 1(MN)0.25 and 1(BTD)0.41 were nonconductive (10–9 S cm–1). This work highlights the potential of metal-free, porous organic systems as tunable semiconductors, offering a pathway to innovative applications in organic electronics. 

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3. Revisiting the Dependence of Poisson’s Ratio on Liquid Fragility and Atomic Packing Density in Oxide Glasses

   https://doi.org/10.3390/ma12152439  

   Østergaard, Martin B.; Hansen, Søren R.; Januchta, Kacper; To, Theany; Rzoska, Sylwester J.; Bockowski, Michal; Bauchy, Mathieu; Smedskjaer, Morten M. (August 2019, Materials)

   Poisson’s ratio (ν) defines a material’s propensity to laterally expand upon compression, or laterally shrink upon tension for non-auxetic materials. This fundamental metric has traditionally, in some fields, been assumed to be a material-independent constant, but it is clear that it varies with composition across glasses, ceramics, metals, and polymers. The intrinsically elastic metric has also been suggested to control a range of properties, even beyond the linear-elastic regime. Notably, metallic glasses show a striking brittle-to-ductile (BTD) transition for ν-values above ~0.32. The BTD transition has also been suggested to be valid for oxide glasses, but, unfortunately, direct prediction of Poisson’s ratio from chemical composition remains challenging. With the long-term goal to discover such high-ν oxide glasses, we here revisit whether previously proposed relationships between Poisson’s ratio and liquid fragility (m) and atomic packing density (Cg) hold for oxide glasses, since this would enable m and Cg to be used as surrogates for ν. To do so, we have performed an extensive literature review and synthesized new oxide glasses within the zinc borate and aluminoborate families that are found to exhibit high Poisson’s ratio values up to ~0.34. We are not able to unequivocally confirm the universality of the Novikov-Sokolov correlation between ν and m and that between ν and Cg for oxide glass-formers, nor for the organic, ionic, chalcogenide, halogenide, or metallic glasses. Despite significant scatter, we do, however, observe an overall increase in ν with increasing m and Cg, but it is clear that additional structural details besides m or Cg are needed to predict and understand the composition dependence of Poisson’s ratio. Finally, we also infer from literature data that, in addition to high ν, high Young’s modulus is also needed to obtain glasses with high fracture toughness. 

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4. N2O dynamics in the western Arctic Ocean during the summer of 2017

   https://doi.org/10.1038/s41598-021-92009-1  

   Heo, Jang-Mu; Kim, Seong-Su; Kang, Sung-Ho; Yang, Eun Jin; Park, Ki-Tae; Jung, Jinyoung; Cho, Kyoung-Ho; Kim, Ju-Hyoung; Macdonald, Alison M; Yoon, Joo-Eun; et al (December 2021, Scientific Reports)

   Abstract The western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N₂O) cycles from greenhouse gases. We investigated WAO N₂O dynamics through an intensive and precise N₂O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N₂O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N₂O production (i.e., through nitrification), with N₂O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N₂O (mean: + 2.3 ± 2.7 μmol N₂O m⁻²day⁻¹), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N₂O m⁻²day⁻¹). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N₂O “hot spot”, and therefore, a key region requiring continued observations to both understand N₂O dynamics and possibly predict their future changes. 

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5. Cooperative C–H activation of pyridine by PBP complexes of Rh and Ir can lead to bridging 2-pyridyls with different connectivity to the B–M unit

   https://doi.org/10.1039/D1SC01850G  

   Cao, Yihan; Shih, Wei-Chun; Bhuvanesh, Nattamai; Zhou, Jia; Ozerov, Oleg V. (November 2021, Chemical Science)

   Pyridine and quinoline undergo selective C–H activation in the 2-position with Rh and Ir complexes of a boryl/bis(phosphine) PBP pincer ligand, resulting in a 2-pyridyl bridging the transition metal and the boron center. Examination of this reactivity with Rh and Ir complexes carrying different non-pincer ligands on the transition metal led to the realization of the possible isomerism derived from the 2-pyridyl fragment connecting either via B–N/C–M bonds or via B–C/N–M bonds. This M–C/M–N isomerism was systematically examined for four structural types. Each of these types has a defined set of ligands on Rh/Ir besides 2-pyridyl and PBP. A pair of M–C/M–N isomers for each type was computationally examined for Rh and for Ir, totaling 16 compounds. Several of these compounds were isolated or observed in solution by experimental methods, in addition to a few 2-quinolyl variants. The DFT predictions concerning the thermodynamic preference within each M–C/M–N isomeric match the experimental findings very well. In two cases where DFT predicts <2 kcal mol −1 difference in free energy, both isomers were experimentally observed in solution. Analysis of the structural data, of the relevant Wiberg bond indices, and of the ETS-NOCV partitioning of the interaction of the 2-pyridyl fragment with the rest of the molecule points to the strength of the M–C(pyridyl) bond as the dominant parameter determining the relative M–C/M–N isomer favorability. This M–C bond is always stronger for the analogous Ir vs. Rh compounds, but the nature of the ligand trans to it has a significant influence, as well. DFT calculations were used to evaluate the mechanism of isomerization for one of the molecule types. 

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