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A Co(II) PNNH pincer catalyst system for the highly E-selective transfer-semihydrogenation of internal alkynes using ammonia borane and MeOH as the hydrogen source is described. The reaction is proposed to occur via the Co(ii) oxidation state.

Catalytic dehydropolymerisation of methylamine borane using the boryl pincer complex [(PBP)Ir(H)(Cl)]/NaOtBu proceeds via an unusual highly fluxional Ir tetrahydride.

Chemoselective semihydrogenation of alkynes to alkenes with E- or Z-stereoselectivity is among the most important transformations in the synthesis of highly functional organic building blocks. Use of hydrogen transfer reagents instead of gaseous hydrogen represents a viable, safe alternative in many cases. This review summarises recent developments in the field using homogeneous, molecularly defined catalyst systems with focus on hydrogen sources and mechanistic aspects of the respective systems.

Many fisheries managers and neoliberal fisheries economists promote Individual Transferable Quotas (ITQs) as a solution to the race for fish which can cause rent dissipation under competitive quota or open access fisheries. These actors consider the Canadian Pacific halibut ITQ fishery an example of successful achievement of these objectives. However, critics note the weak performance of this management model in distribution of benefits, increased capital costs to fishermen, deteriorating safety conditions, reductions in crew income and barriers to entry. They point to the layup system which successfully managed effort in the Pacific halibut fishery for four decades prior to the introduction of ITQs. A system similar to the layup has been used for Atlantic halibut since 2013, initiated by the Fish Food and Allied Workers (FFAW) representing owner‐operator license holders in the halibut fishery off the coast of western Newfoundland and southern Labrador. The FFAW rejected the two halibut management plan options presented to them by Fisheries and Oceans Canada: the status quo (a competitive 12‐hr “derby” fishery) or IQs, likely leading to ITQs. Instead, the FFAW worked with license holders to develop a management plan that required harvesters to choose between different fishing periods that spread fishing opportunities over time. This approach improved conservation results, delivered strong economic returns, distributed benefits widely to active fishermen, and allowed an even flow into the market. The authors consider the advantages of these Canadian east and west coast halibut co‐management systems and their broader application.

Correction for ‘Catalytic and mechanistic studies of a highly active and E-selective Co(ii) PNNH pincer catalyst system for transfer-semihydrogenation of internal alkynes’ by David Decker et al., Inorg. Chem. Front., 2022, DOI: 10.1039/d1qi00998b.

Six new 8-styryl-substituted coralyne derivatives 4a–f were synthesized from coralyne (2) by a base catalysed Knoevenagel type reaction. It was shown by photometric and fluorimetric titrations of double stranded and quadruplex DNA to 4b–d as well as by fluorimetric DNA denaturation experiments that these ligands bind to DNA with different binding modes at varying ligand-DNA ratios (LDR). Specifically, the addition of DNA caused initially a hypochromic effect in absorbance and, at a particular LDR, the development of a new red shifted absorption band with a hyperchromic effect. Furthermore, 4b–d induced a significant and selective stabilization of quadruplex DNA towards unfolding (ΔTm = 31.6–32.9 °C at LDR = 5), which is even more pronounced as compared to the parent compound coralyne (2). Most notably, the addition of DNA to the dimethylamino-substituted derivative 4b leads to a new, strongly red-shifted emission band at 695 nm. Hence, this derivative is a fluorescent probe that changes its fluorescence colour from green to red in the presence of DNA and even allows the fluorimetric analysis of living cells by staining of the nucleoli.

BACKGROUND High-flow intracranial arteriovenous (AV) fistulas associated with giant varices are rare lesions. These varices can present with symptoms from mass effect, spontaneous hemorrhage, and seizures to cardiac failure. Direct AV fistulas of the posterior inferior cerebellar artery (PICA) are extremely rare lesions, with only two cases reported in the literature. CASE DESCRIPTION The authors present an unusual case of a 25-year-old male with a direct AV fistula of the PICA that resulted from a fracture of the occipital condyle. This high-flow AV fistula drained into a giant varix of the vein of the lateral recess that compressed the brainstem, resulting in a Wallenberg syndrome. The patient underwent embolization of the proximal PICA feeding the fistula with a Guglielmi detachable coil (GDC), which resulted in thrombosis of the varix. A postembolization angiogram showed occlusion of the PICA AV fistula and draining varix. A computed tomography (CT) scan performed at a 10-month follow-up visit showed dramatic decompression of the brainstem. Although the patient continued to have some sensory changes secondary to Wallenberg syndrome, he was otherwise doing well neurologically. CONCLUSION The treatment of this lesion is difficult because of its location near the brainstem. Postocclusion edema or hemorrhage can result in mass effect and life-threatening brainstem compression. Our patient, whose AV fistula was caused by trauma, was treated effectively with GDC embolization.

Eight laser dyes emitting in the spectral region from 550 to 915 nm were investigated to determine their power scalability under excitation by Q‐switched frequency‐doubled Nd : YAG lasers possessing up to 480 mJ pulse energy at 10 Hz pulse repetition frequency (PRF). Conversion efficiencies for some dyes begin to be limited at pump‐power densities as low as 14 MW/cm2 due to excited‐state absorption of the pumping radiation. The dependence on resonator length of dye spectral emission, conversion efficiency, and temporal modulation are reported. Divergence of the beam emerging from the dye laser was found to be adversely affected by measures taken to avoid output power saturation at high pump‐power densities.

The development of a high peak and average power stimulated Raman scattering (SRS) source with a dye amplifier is described. Emission from 505 to 771 nm is obtained using 532‐nm radiation from a frequency‐doubled Nd : YAG laser as the optical pump. Dimethyl sulfoxide (DMSO) is found to be a very efficient SRS medium, and produces 40% energy conversion from 532 to 630 nm at 10 pulses/sec. Use of a dye amplifier increases energy conversion efficiency to 60%. Mixtures of DMSO and d‐DMSO are found to emit the I and II Stokes lines of each material, plus a ’’mixed’’ mode line at 727 nm. SRS is also shown to be a limiting phenomenon in the power scaling of laser‐pumped dye lasers.

Efficient near‐infrared dye laser emission has been achieved in the 838–923‐nm range by use of a frequency‐doubled Nd:YAG laser as the optical pump for various polymethine dyes. Experimental evidence of 1064‐nm quenching of the dye laser emission is reported. Strong excited state absorption (ESA) effects are observed for the dye IR‐140 at the 532‐nm pump wavelength. This excited state absorption results in an experimentally determined optimum pump power density of 50–60 MW/cm2 for maximum dye laser efficiency. Such excited state absorption may thus be a limiting factor in the power scaling of pulsed dye lasers.

The 5106‐A output of a 250‐mW copper‐vapor laser has been used to obtain laser action in a Rhodamine 6G dye laser. The high gain of such a copper‐vapor laser pumped dye solution has been demonstrated by amplifying the 5782‐A output of the same copper‐vapor laser.