TRNA molecules contain dense, abundant modifications that affect tRNA structure, stability, mRNA decoding and tsRNA formation. tRNA modifications and related enzymes are responsive to environmental cues and are associated with a range of physiological and pathological processes. However, there is a lack of resources that can be used to mine and analyse these dynamically changing tRNA modifications. In this study, we established tModBase (https://www.tmodbase.com/) for deciphering the landscape of tRNA modification profiles from epitranscriptome data. We analysed 103 datasets generated with second- and third-generation sequencing technologies and illustrated the misincorporation and termination signals of tRNA modification sites in ten species. We thus systematically demonstrate the modification profiles across different tissues/cell lines and summarize the characteristics of tRNA-associated human diseases. By integrating transcriptome data from 32 cancers, we developed novel tools for analysing the relationships between tRNA modifications and RNA modification enzymes, the expression of 1442 tRNA-derived small RNAs (tsRNAs), and 654 DNA variations. Our database will provide new insights into the features of tRNA modifications and the biological pathways in which they participate.

Six examples of 2-(1-arylimino)ethyl-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridine-cobalt(II) chloride complexes, [2-(1-ArN)C₂H₃-9-ArN-5,6,7,8-C₅H₈C₅H₃N]CoCl₂, (Ar = 2-(C₅H₉)-6-MeC₆H₃ Co1, 2-(C₆H₁₁)-6-MeC₆H₃ Co2, 2-(C₈H₁₅)-6-MeC₆H₃ Co3, 2-(C₅H₉)-4,6-Me₂C₆H₂ Co4, 2-(C₆H₁₁)-4,6-Me₂C₆H₂ Co5, and 2-(C₈H₁₅)-4,6-Me₂C₆H₂ Co6), were synthesized by the direct reaction of the corresponding ortho-cycloalkyl substituted carbocyclic-fused bis(arylimino)pyridines (L1–L6) and cobalt(II) chloride in ethanol with good yields. All the synthesized ligands (L1–L6) and their corresponding cobalt complexes (Co1–Co6) were fully characterized by FT-IR, ¹H/¹³C-NMR spectroscopy and elemental analysis. The crystal structure of Co2 and Co3 revealed that the ring puckering of both the ortho-cyclohexyl/cyclooctyl substituents and the one pyridine-fused seven-membered ring; a square-based pyramidal geometry is conferred around the metal center. On treatment with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the six complexes showed high activities (up to 4.09 × 10⁶ g of PE mol⁻¹ (Co) h⁻¹) toward ethylene polymerization at temperatures between 20 °C and 70 °C with the catalytic activities correlating with the type of ortho-cycloalkyl substituent: Cyclopentyl (Co1 and Co4) > cyclohexyl (Co2 and Co5) > cyclooctyl (Co3 and Co6) for either R = H or Me and afforded strictly linear polyethylene (T_m > 130 °C). The narrow unimodal distributions of the resulting polymers are consistent with single-site active species for the precatalyst. Furthermore, compared to the previously reported cobalt analogues, the titled precatalysts exhibited good thermo-stability (up to 70 °C) and possessed longer lifetime along with a higher molecular weight of PE (M_w: 9.2~25.3 kg mol⁻¹).

Five chromium(III) chloride complexes, [2-{(Ar)NCMe}-9-{N(Ar)}C₁₀H₁₀N]CrCl₃ (Ar = 2,6-Me₂C₆H₃Cr1, 2,6-Et₂C₆H₃Cr2, 2,6-i-Pr₂C₆H₃Cr3, 2,4,6-Me₃C₆H₂Cr4, 2,6-Et₂-4-MeC₆H₂Cr5), each chelated by a sterically and electronically different cycloheptyl-fused N,N,N′-bis(imino)pyridine, have been synthesized by the reactions of CrCl₃(THF)₃ with the corresponding ligand (L1/L1′–L5/L5′). The molecular structure of Cr2 highlights both the steric properties exerted by the inequivalent N-2,6-ethylphenyl groups and the puckering of the fused cycloheptyl ring; a distorted octahedral geometry is conferred about the metal center. On activation with methylaluminoxane (MAO) or modified MAO (MMAO), Cr1–Cr5 displayed their optimal activity for ethylene polymerization at temperatures between 70 and 80 °C with the least sterically demanding Cr1 proving the most productive (1.44 × 10⁷ g (PE) per mol (Cr) per h). The polyethylenes formed are of low molecular weight (M_w range: 0.66–3.56 kg mol⁻¹) with narrow molecular weight distributions and display high levels of end-group unsaturation. Furthermore, the amenability of these vinyl-terminated polyethylenes to undergo functionalization via epoxidation has been demonstrated.

Five examples of unsymmetrical 2-(2,4-bis(dibenzocycloheptyl)-6-methylphenyl- imino)ethyl)-6-(1-(arylyimino)ethyl)pyridine derivatives (aryl = 2,6-Me₂C₆H₃ in L1; 2,6-Et₂C₆H₃ in L2; 2,6-i-Pr₂C₆H₃ in L3; 2,4,6-Me₃C₆H₂ in L4 and 2,6-Et₂-4-MeC₆H₂ in L5) were prepared and characterized. Treatment with CoCl₂ offered the corresponding cobalt precatalysts Co1–Co5, which were characterized by FT-IR and NMR spectroscopy as well as elemental analysis. The molecular structures of Co3 and Co4 determined by single crystal X-ray diffraction revealed distorted square pyramidal geometries with τ₅ values of 0.052–0.215. Activated with either MAO or MMAO, the precatalysts displayed high activities in ethylene polymerization, where Co1 with the least bulky substituents exhibited a peak activity of 1.00 × 10⁷ g PE mol⁻¹ (Co) h⁻¹ at 60 °C. With MAO as a cocatalyst, the activity was reduced only by one order of magnitude at 90 °C, which implies thermally stable active sites. The polymerization product was highly linear polyethylene with vinyl end groups. Co3 with the most sterically hindered active sites was capable of generating polyethylene of high molecular weight, reaching 6.46 × 10⁵ g mol⁻¹. Furthermore, high melting point and unimodal molecular weight distribution were observed in the resulting polyethylene. It must be stressed that the thermal stability of the catalyst and the molecular weight of the obtained polyethylene attain the highest values reported for the unsymmetrical 2,6-bis(imino)pyridylcobalt (II) chloride precatalysts.

A key decision for semiconductor suppliers is how to allocate available product lots to customer orders when demand exceeds supply. The problem, known as the generalised lot allocation (GLA) problem in semiconductor supply chains, can be formulated as a combinatorial optimisation problem with the objective of minimising total backorder and tardiness penalties as well as total product downgrade and product excess costs. The lot-integrity requirement, a de facto standard in the semiconductor industry, makes the problem non-deterministic polynomial-time (NP)-hard. Different lot allocation decision policies are evaluated and compared using representative data sets. Computational test results indicate composite allocation rule (CAR)-based policies can improve the quality of the solution and reduce the cost of the solution significantly.

Through the implementation of a one-pot strategy, five examples of non-symmetrical [N,N-diaryl-11-phenyl-1,2,3,7,8,9,10-heptahydrocyclohepta[b]quinoline-4,6-diimine]iron(II) chloride complexes (aryl = 2,6-Me₂Ph Fe1, 2,6-Et₂Ph Fe2, 2,6-i-Pr₂Ph Fe3, 2,4,6-Me₃Ph Fe4, and 2,6-Et₂-4-MePh Fe5), incorporating fused six- and seven-membered carbocyclic rings and appended with a remote para-phenyl group, were readily prepared. The molecular structures of Fe2 and Fe3 emphasize the variation in fused ring size and the skewed disposition of the para-phenyl group present in the N′,N,N″-ligand support. Upon activation with MAO or MMAO, Fe1–Fe5 all showed high catalytic activity for ethylene polymerization, with an exceptional level of 35.92 × 10⁶ g (PE) mol⁻¹ (Fe) h⁻¹ seen for mesityl-substituted Fe4/MMAO operating at 60 °C. All catalysts generated highly linear polyethylene with good control of the polymer molecular weight achievable via straightforward manipulation of run temperature. Typically, low molecular weight polymers with narrow dispersity (M_w/M_n = 1.5) were produced at 80 °C (MMAO: 3.7 kg mol⁻¹ and MAO: 4.9 kg mol⁻¹), while at temperatures between 40 °C and 50 °C, moderate molecular weight polymers were obtained (MMAO: 35.6–51.6 kg mol⁻¹ and MAO: 72.4–95.5 kg mol⁻¹). Moreover, analysis of these polyethylenes by ¹H and ¹³C NMR spectroscopy highlighted the role played by both β-H elimination and chain transfer to aluminum during chain termination, with the highest rate of β-H elimination seen at 60 °C for the MMAO-activated system and 70 °C for the MAO system.