Single crystals of l-O-serine phosphate, (HOOC)CH(NH3 +)CH2OPO3 -H, were X-irradiated at 295 K and studied using EPR, ENDOR, and FSE techniques. At this temperature, three carbon-centered radicals were identified. Radical I, the deamination product (HOOC)ĊHCH2OPO3 -H, is shown to have undergone a major molecular reorientation upon formation. Radical II is identified to be the product (HOOC)CH(NH3 +)ĊHOPO3 -H. This species exhibits a nonplanar site for the lone electron density. This deviation from planarity is ascribed to electrostatic interaction between the lone electron orbital and lone pairs centered on the neighboring oxygen atom. Hyperfine interaction with the β-nitrogen of the amino group is observed. Both the 14N hyperfine and quadrupole coupling tensors are determined and the signs of the hyperfine coupling tensor principal values are deduced from interpretation of the quadrupole tensor employing the Townes−Dailey approach. The β14N isotropic interaction is well described by a Heller and McConnell type cos2 θ rule. The results found in the present work, together with other recent observations, yield estimated values of the constants B 0 = 1.0 MHz and B 2 = 34.5 MHz. Radical III exhibits the structure (HOOC)CH(NH3 +)ĊH2, formed by scission of the phosphate−ester bond at the carbon side. No β14N coupling is observed for this radical due to a dihedral angle close to 90°. Possible mechanistic routes for the formation of these radicals are discussed in comparison with previously published data on serine and other alkyl phosphate derivatives.

The solid-state radiation-induced free radical formation in simple amino acids like alpha-glycine (gly) and L-alpha-alanine (ala) has been the subject of investigations by EPR spectroscopy since the late 1950s. The EPR spectra from crystals of gly and ala generally are very complex due to the simultaneous trapping of several free radicals regardless of irradiation and observation temperatures. Untangling these complex spectra is necessary for understanding the mechanisms for the solid-state radiation chemistry of amino acids. Recently, radical formation in gly and ala after room-temperature irradiation has been reinvestigated in our laboratories using X-, K- and Q-band EPR and ENDOR spectroscopy, combined with the ENDOR-induced EPR (EIE) techniques as well as single-crystal and powder EPR and ENDOR spectrum simulations. Several new radical products have been detected and characterized, most prominently the gly species H2N - C x H - COOH and the ala species H3+N - C x (CH3) - COO and H2N - C x (CH3) - COOH. A short description of these radicals is given, and an overview of the solid-state radiation chemistry of the simple amino acids is presented, based on a review of the literature combined with these recent experimental results.

Single crystals of the phosphorylated amino acid L-O-serine phosphate were X-irradiated and studied at 10 K and at 77 K using EPR, ENDOR, and EIE techniques. Two radicals, R1(10 K) and R1(77 K), were detected and characterized as two different geometrical conformations of the protonated reduction product >CH-C(OH)(2). R1(10 K) is only observed after irradiation at 10 K, and upon heating to 40 K, R1(10 K) transforms rapidly and irreversibly into R1(77 K). The transition from R1(10 K) to R1(77 K) strongly increases the isotropic hyperfine coupling of the C-CH(beta) coupling (Delta = 32 MHz) and the major C-OH(beta) coupling (Delta = 47 MHz), in sharp contrast to the their much reduced anisotropic hyperfine couplings after the transition. An umbrella-like inversion of the carboxylic acid center, accompanied by minor geometrical adjustments, explains the changes of these observed isotropic and anisotropic couplings. DFT calculations were done on the reduced and protonated L-O-serine phosphate radical at the B3LYP/6-311+G(2df,p)//B3LYP/6-31+G(d) level of theory in order to support the experimental observations. Two different conformations of the anion radical, related by an inversion at the carboxylic center, could be found within the single molecule partial energy-optimization scheme. These two conformations reproduce the experimental hyperfine couplings from radicals R1(10 K) and R1(77 K). A third radical, radical R2, was observed experimentally at both 10 and 77 K and was shown to be due to the decarboxylated L-O-serine phosphate oxidation product, a conclusion fully supported from the DFT calculations. Upon thermal annealing from 77 to 295 K, radicals R1(77 K) and R2 disappeared and all three previously observed room-temperature radicals could be observed. No phosphate-centered radicals could be observed at any temperatures, indicating that the phosphate-ester bond break for one of the room-temperature radicals does not occur by dissociative electron capture at the phosphate group.

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Introduction: It has been suggested that the future of diagnostic imaging relies on engagement in research and evidence-based practice. This implies a role transition from a clinical radiographer to a clinical radiographer-researcher. Clinical radiographers' stimuli for engaging in research in Nordic countries are unknown. This study aimed to address this gap. Methods: Cross-sectional data collection via an online questionnaire on facilitators for and barriers to participation in radiography research was carried out among 507 clinical radiographers in public healthcare in the Nordic countries: Denmark, Finland, Norway and Sweden. Results: Support from colleagues (odds ratio [OR] 2.62) and other professionals (OR 2.74), and selfesteem in research skills (OR 2.21), were facilitators for radiography research. Lack of knowledge and skills to conduct research (OR 2.48) was revealed to hinder radiographers' participation in research. The absence of a radiography research culture in the workplace explained non-participation in research (OR 1.75). Conclusion:This study revealed significant factors for clinical radiographers' participation in research. Implications for practice: A strategy for establishing a radiography research culture in healthcare is proposed that is novel for the context. Management support for knowledge development and activity leading to inter-professional research projects across knowledge fields, provision of a radiography research lead and acknowledgement of radiography research among colleagues signify the establishment of the culture. These prerequisites might provide a paradigm change towards not only the symbiosis of a clinical radiographer and an autonomous researcher but also a partner who adds radiography research to evidence-based practice in diagnostic imaging.