Hyperbolic Polaritons in Topological Nodal Ring Semimetals.

In mirror-symmetric systems, there is a possibility of the realization of extended gapless electronic states characterized as nodal lines or rings. Strain induced modifications to these states lead to the emergence of different classes of nodal rings with qualitatively different physical properties. Here we study optical response and the electromagnetic wave propagation in type I nodal ring semimetals, in which the low-energy quasiparticle dispersion is parabolic in momentum k_{x} and k_{y} and is linear in k_{z}. This leads to a highly anisotropic dielectric permittivity tensor in which the optical response is plasmonic in one spatial direction and dielectric in the other two directions. The resulting normal modes (polaritons) in the bulk material become hyperbolic over a broad frequency range, which is furthermore tunable by the doping level. The propagation, reflection, and polarization properties of the hyperbolic polaritons not only provide valuable information about the electronic structure of these fascinating materials in the most interesting region near the nodal rings but also pave the way to tunable hyperbolic materials with applications ranging from anomalous refraction and waveguiding to perfect absorption in ultrathin subwavelength films.

Cofactors and pathogens: Flavin mononucleotide and flavin adenine dinucleotide (FAD) biosynthesis by the FAD synthase from Brucella ovis.

The biosynthesis of the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), cofactors used by 2% of proteins, occurs through the sequential action of two ubiquitous activities: a riboflavinkinase (RFK) that phosphorylates the riboflavin (RF) precursor to FMN, and a FMN:adenylyltransferase (FMNAT) that transforms FMN into FAD. In most mammals two different monofunctional enzymes have each of these activities, but in prokaryotes a single bifunctional enzyme, FAD synthase (FADS), holds them. Differential structural and functional traits for RFK and FMNAT catalysis between bacteria and mammals, as well as within the few bacterial FADSs so far characterized, has envisaged the potentiality of FADSs from pathogens as targets for the development of species-specific inhibitors. Here, we particularly characterize the FADS from the ovine pathogen Brucella ovis (BoFADS), causative agent of brucellosis. We show that BoFADS has RFK activity independently of the media redox status, but its FMNAT activity (in both forward and reverse senses) only occurs under strong reducing conditions. Moreover, kinetics for flavin and adenine nucleotides binding to the RFK site show that BoFADS binds preferentially the substrates of the RFK reaction over the products and that the adenine nucleotide must bind prior to flavin entrapment. These results, together with multiple sequence alignments and phylogenetic analysis, point to variability in the less conserved regions as contributing to the species-specific features in prokaryotic FADSs, including those from pathogens, that allow them to adopt alternative strategies in FMN and FAD biosynthesis and overall flavin homeostasis.

Risk-score based strategy to minimize antibiotic exposure in children with sickle cell disease and fever.

Severe bacterial infections (SBI) have become less frequent in children with sickle cell disease (SCD) in the last decades. However, because of their potential risk of SBI, they usually receive empirical therapy with broad-spectrum antibiotics when they develop fever and are hospitalized in many cases. We performed a prospective study including 79 SCD patients with fever [median age 4.1 (1.7-7.5) years, 78.5% males; 17 of the episodes were diagnosed with SBI and 4 of them were confirmed] and developed a risk score for the prediction of SBI. The optimal score included CRP > 3 mg/dl, IL-6 > 125 pg/ml and hypoxemia, with an AUC of 0.91 (0.83-0.96) for the prediction of confirmed SBI and 0.86 (0.77-0.93) for possible SBI. We classified the patients in 3 groups: low, intermediate and high risk of SBI. Our risk-score-based management proposal could help to safely minimize antibiotic treatments and hospital admissions in children with SCD at low risk of SBI.

The Place of Care under Constraint for Mood Disorders in the Context of the Collapse of the Supply of Psychiatric Care during the COVID-19 Crisis.

BACKGROUND: In March 2020, the Belgian population was exposed to a confinement situation that it had never experienced before associated with the collapse in access to psychiatric care. Initially, only emergencies and constrained care continued to operate. In these specific circumstances, where both the overall population and the psychiatric population, was exposed to unique stress factors, what was the role of forced psychiatric internments in the treatment of mood disorders? SUBJECTS AND METHODS: We have measured the number of detentions for observation with and without suicide attempt over the two years prior to the pandemic in order to obtain theoretical reference values. We have compared these values with the measures over the 12 months following the start of the confinement period, which constitute the Crisis values. The continuation of measures, with an equal number of observation measures, constituted the Post-Crisis values. For these same cases, we compared in suicide attempt cases, whether the criteria for Severe Major Depressive Disorder were met or not. Lastly we compared the number of observation measures that were lifted, or not, within ten days of patient care. RESULTS: There was no significant increase in Detentions for Observation following a suicide attempt during the Crisis period. However a significant increase was observed during the Post-Crisis period. As regards cases of attempted suicide during the Crisis period, the number of patients suffering from Major Depressive Disorders reduced significantly in terms of statistics. This confirms our impression of a change in population. The Post-Crisis values dropped to the Theoric values. The number of Observation measures lifted increased quite significantly during the Crisis period, while there was a return to values in terms of statistics similar to the Theoric values during the Post-Crisis period. CONCLUSIONS: Although the population, both the healthy population and those suffering from a psychiatric condition, was subject to stress that it had never before experienced coinciding with a collapse of healthcare provision, there was no increase in patients meeting the criteria to benefit from constrained care during the Crisis period. On the other hand, there was a significant change in statistical terms in the population of patients who attempted suicide. We have seen a collapse in the number of patients suffering from depressive disorders and an equivalent increase in the number of patients with personality disorders or adjustment disorders. The number of Observation measures lifted during the Crisis period also grew quite significantly. Constrained care was available to help manage reactive suicide attempts. All other things being equal, they indirectly showed a reduction in Major Depressive Disorders requiring constrained care in the population.

Interleukin 6 as a marker of severe bacterial infection in children with sickle cell disease and fever: a case-control study.

BACKGROUND: Etiological diagnosis of fever in children with sickle cell disease (SCD) is often challenging. The aim of this study was to analyze the pattern of inflammatory biomarkers in SCD febrile children and controls, in order to determine predictors of severe bacterial infection (SBI). METHODS: A prospective, case-control study was carried out during 3 years, including patients younger than 18 years with SCD and fever (cases) and asymptomatic steady-state SCD children (controls). Clinical characteristics and laboratory parameters, including 10 serum proinflammatory cytokines (IL-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17a, IFN-γ and TNF-α) and comparisons among study subgroups were analyzed. RESULTS: A total of 137 patients (79 cases and 58 controls) were included in the study; 78.5% males, median age 4.1 (1.7-7.5) years. Four cases were diagnosed with SBI, 41 viral infection (VI), 33 no proven infection (NPI) and 1 bacterial-viral coinfection (the latter excluded from the subanalyses). IL-6 was significantly higher in patients with SBI than in patients with VI or NPI (163 vs 0.7 vs 0.7 pg/ml, p < 0.001), and undetectable in all controls. The rest of the cytokines analyzed did not show any significant difference. The optimal cut-off value of IL-6 for the diagnosis of SBI was 125 pg/mL, with high PPV and NPV (PPV of 100% for a prevalence rate of 5, 10 and 15% and NPV of 98.7%, 97.3% and 95.8% for those prevalences rates, respectively). CONCLUSION: We found that IL-6 (with a cut-off value of 125 pg/ml) was an optimal marker for SBI in this cohort of febrile SCD children, with high PPV and NPV. Therefore, given its rapid elevation, IL-6 may be useful to early discriminate SCD children at risk of SBI, in order to guide their management.

Green silver-nanoparticle-based dual sensor for toxic Hg(II) ions.

The present study focuses on the utilization of green silver nanoparticles, as they are preferred for sensing applications due to their environmentally friendly nature. We have examined the optical and electrochemical sensing behavior of silver nanoparticles from Agaricus bisporus (AgNP-AB) towards Hg(II) ions. The AgNP-AB was prepared by microwave reactor. The synthesized AgNP was used for the sensing of Hg(II) ions without the use of modifiers or further sophisticated instrumentation. The synthesized nanoparticles were successfully characterized by different techniques. AgNP-AB leads to aggregation with the addition of Hg(II) ions in aqueous medium, and develops a color change from brown to black which leads to the formation of AgNP-AB-Hg(II) complex. Moreover, the metal sensing ability of AgNP has been explored using electrochemical studies. AgNP-AB modified platinum electrode (AgNP-AB/PE) was developed for the fast sensing of toxic Hg(II) ions. The sensor exhibits a good limit of detection at 2.1 × 10-6 M. The sensitivity of AgNP-AB/PE towards Hg(II) ions was analyzed with various metal ions. The sensing skill of the developed system was successfully checked with real water samples from Vembanade Lake, Kumarakom, Kerala. AgNP from A. bisporus is highly versatile and promising for different environmental applications.

The RFK catalytic cycle of the pathogen Streptococcus pneumoniae shows species-specific features in prokaryotic FMN synthesis.

Emergence of multidrug-resistant bacteria forces us to explore new therapeutic strategies, and proteins involved in key metabolic pathways are promising anti-bacterial targets. Bifunctional flavin-adenine dinucleotide (FAD) synthetases (FADS) are prokaryotic enzymes that synthesise the flavin mononucleotide (FMN) and FAD cofactors. The FADS from the human pathogen Streptococcus pneumoniae (SpnFADS)-causative agent of pneumonia in humans - shows relevant catalytic dissimilarities compared to other FADSs. Here, by integrating thermodynamic and kinetic data, we present a global description of the riboflavin kinase activity of SpnFADS, as well as of the inhibition mechanisms regulating this activity. Our data shed light on biophysical determinants that modulate species-specific conformational changes leading to catalytically competent conformations, as well as binding rates and affinities of substrates versus products. This knowledge paves the way for the development of tools - that taking advantage of the regulatory dissimilarities during FMN biosynthesis in different species - might be used in the discovery of specific anti-pneumococcal drugs.

Discovery of antimicrobial compounds targeting bacterial type FAD synthetases.

The increase of bacterial strains resistant to most of the available antibiotics shows a need to explore novel antibacterial targets to discover antimicrobial drugs. Bifunctional bacterial FAD synthetases (FADSs) synthesise the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These cofactors act in vital processes as part of flavoproteins, making FADS an essential enzyme. Bacterial FADSs are potential antibacterial targets because of differences to mammalian enzymes, particularly at the FAD producing site. We have optimised an activity-based high throughput screening assay targeting Corynebacterium ammoniagenes FADS (CaFADS) that identifies inhibitors of its different activities. We selected the three best high-performing inhibitors of the FMN:adenylyltransferase activity (FMNAT) and studied their inhibition mechanisms and binding properties. The specificity of the CaFADS hits was evaluated by studying also their effect on the Streptococcus pneumoniae FADS activities, envisaging differences that can be used to discover species-specific antibacterial drugs. The antimicrobial effect of these compounds was also evaluated on C. ammoniagenes, S. pneumoniae, and Mycobacterium tuberculosis cultures, finding hits with favourable antimicrobial properties.

The attitude of Latin American immigrants in Florida (USA) towards deceased organ donation - a cross section cohort study.

The Latin American (LA) population resident in the USA is a growing subgroup of the population. To find out the structure of attitude towards organ donation in the LA population resident in Florida (USA). A sample was taken of LA residents in Florida, randomized and stratified by nationality, age and sex (n = 1524). Attitude was assessed using a validated questionnaire (PCID-DTO Rios) that was self-completed anonymously. The survey completion rate was 95% (n = 1450). Attitude was favourable in 33% of respondents (n = 485), against in 40% (n = 575) and undecided in 27% (n = 390). The following variables were associated with a favourable attitude: country of origin (Dominican Republic; P = 0.038); sex (female; P < 0.001); marital status (married; P < 0.001); level of education (university; P < 0.001); previous experience of the subject (P < 0.001); considering the need for a transplant in the future (P < 0.001); understanding the concept of brain death (P = 0.003); attitude towards donating a family member's organs (P < 0.001); having discussed organ donation and transplantation with one's family (P < 0.001) or with one's partner (P < 0.001); participation in pro-social type activities (P < 0.001); the respondent's religion (atheist-agnostic; P < 0.001); a respondent's knowledge of the attitude of his or her religion towards organ donation (P < 0.001); no concern about mutilation after donation (P < 0.001); acceptance of cremation (P < 0.001); burial (P < 0.001); and an autopsy if one were needed (P < 0.001). The attitude towards donation of LA in Florida is worse than that reported in the native population and is associated with certain psychosocial factors.

Quaternary organization in a bifunctional prokaryotic FAD synthetase: Involvement of an arginine at its adenylyltransferase module on the riboflavin kinase activity.

Prokaryotic FAD synthetases (FADSs) are bifunctional enzymes composed of two modules, the C-terminal module with ATP:riboflavin kinase (RFK) activity, and the N-terminus with ATP:FMN adenylyltransferase (FMNAT) activity. The FADS from Corynebacterium ammoniagenes, CaFADS, forms transient oligomers during catalysis. These oligomers are stabilized by several interactions between the RFK and FMNAT sites from neighboring protomers, which otherwise are separated in the monomeric enzyme. Among these inter-protomer interactions, the salt bridge between E268 at the RFK site and R66 at the FMNAT-module is particularly relevant, as E268 is the catalytic base of the kinase reaction. Here we have introduced point mutations at R66 to analyze the impact of the salt-bridge on ligand binding and catalysis. Interestingly, these mutations have only mild effects on ligand binding and kinetic properties of the FMNAT-module (where R66 is located), but considerably impair the RFK activity turnover. Substitutions of R66 also modulate the ratio between monomeric and oligomeric species and modify the quaternary arrangement observed by single-molecule methods. Therefore, our data further support the cross-talk between the RFK- and FMNAT-modules of neighboring protomers in the CaFADS enzyme, and establish the participation of R66 in the modulation of the geometry of the RFK active site during catalysis.

The Spanish Validation of the Accommodation and Enabling Scale for Eating Disorders Among Carers: A Pilot Study.

Literature suggests that families may accommodate patients' symptoms in attempts to alleviate family conflict and stress. These accommodating and enabling behaviours may have a negative impact on carers and those they care for. There are no self-report questionnaires validated in Spanish to measure accommodation among relatives of patients with an eating disorder. The aim of this study was to examine the psychometric properties of the Spanish version of the Accommodation and Enabling Scale for Eating Disorders (AESED-S) among relatives of eating disorder patients. A cross-sectional study of 90 relatives was carried out to explore the factor structure, reliability and validity of the AESED-S. The internal consistency of the Spanish version of the AESED subscales was good, ranging from .89 to .81. The correlation of the five subscales with conceptually related measures (negative caregiving experience and distress) supports the convergent validity of this instrument in this sample. Results indicated that the Spanish version of the AESED provides a reliable and valid tool for assessing family accommodation in the context of having a relative with an eating disorder.

Structural insights into the synthesis of FMN in prokaryotic organisms.

Riboflavin kinases (RFKs) catalyse the phosphorylation of riboflavin to produce FMN. In most bacteria this activity is catalysed by the C-terminal module of a bifunctional enzyme, FAD synthetase (FADS), which also catalyses the transformation of FMN into FAD through its N-terminal FMN adenylyltransferase (FMNAT) module. The RFK module of FADS is a homologue of eukaryotic monofunctional RFKs, while the FMNAT module lacks homologyto eukaryotic enzymes involved in FAD production. Previously, the crystal structure of Corynebacterium ammoniagenes FADS (CaFADS) was determined in its apo form. This structure predicted a dimer-of-trimers organization with the catalytic sites of two modules of neighbouring protomers approaching each other, leading to a hypothesis about the possibility of FMN channelling in the oligomeric protein. Here, two crystal structures of the individually expressed RFK module of CaFADS in complex with the products of the reaction, FMN and ADP, are presented. Structures are complemented with computational simulations, binding studies and kinetic characterization. Binding of ligands triggers dramatic structural changes in the RFK module, which affect large portions of the protein. Substrate inhibition and molecular-dynamics simulations allowed the conformational changes that take place along the RFK catalytic cycle to be established. The influence of these conformational changes in the FMNAT module is also discussed in the context of the full-length CaFADS protomer and the quaternary organization.

[Hospital-based multicenter study in Spain, Mexico and Cuba on attitudes to living liver donation]. / Estudio multicéntrico hospitalario en España, México y Cuba de actitud hacia la donación de vivo hepática.

INTRODUCTION: Given the lack of a sufficient number of livers available for transplantation, living liver donation (LLD) is being developed in the Spanish-speaking world. To do this, it is essential that health workers in hospitals are in favor of such donation, given that they are a key component in this treatment and that their attitudes influence public opinion. OBJECTIVE: To analyze attitude toward LLD among hospital personnel from healthcare centers in Spain and Latin America. MATERIAL AND METHOD: Ten hospitals were selected from the «International Donor Collaborative Project¼: 3 from Spain, 5 from Mexico and 2 from Cuba. Random sampling stratified by type of service and job category was used. Attitudes to LLD were evaluated through a validated questionnaire on psychosocial aspects. The questionnaire was anonymous and self-administered. Statistical tests consisted of Student's T test, the chi-square test and logistic regression analysis. RESULTS: Of the 2,618 employees surveyed, 85% (n=2,231) were in favor of related LLD; of these, 31% (n=804) were in favor of unrelated LLD. No association was found between the country of the interviewed, personal-social variables or work-related variables. The following factors were associated with a favorable attitude toward related LLD donation: having had personal experience of donation and transplantation (P<.001); being in favor of deceased donation (P<.001); believing that one might need a possible transplant (P<.001); being in favor of living kidney donation (P<.001); being willing to accept a liver from a living donor (P<.001); having discussed the matter of donation and transplantation within the family (P<.001) and with one's partner (P<.001); carrying out pro-social type activities (P<.001); being Catholic (P=.040); believing that one's religion is in favor of donation and transplantation (P<.001); and not being concerned about the possible mutilation of the body after donation (P<.001). CONCLUSIONS: Hospital personnel from Spain and Latin America had a favorable attitude toward LLD, which was associated with factors directly and indirectly related to donation and transplantation, family and religious factors, and attitudes toward the body.

[Lopinavir/ritonavir in new simplification strategies in antiretroviral therapy]. / Lopinavir/ritonavir en nuevas estrategias de simplificación del tratamiento antirretroviral.

Interest in simplification arises from the need to dispense with nucleoside analogs due to their long-term toxicity. Since the first trials analyzing the safety and effectiveness of the strategy with lopinavir/ritonavir (LPV/r) emerged more than 10 years ago, simplification continues to arouse scientific, clinical and economic interest. At present, there is no consensus on recommendations; interpretations of results are discordant: while some emphasize the greater risk of loss of virologic control, others indicate that the possible virological rebound with this strategy is unrelated to a loss of therapeutic options or to the emergence of resistance to ritonavir-boosted protease inhibitors. This scenario governs the recommendations that can be made in clinical practice; almost all groups agree that candidates should be selected for a simplification strategy with fewer drugs.

Persistent hexavalent chromium exposure impaired the pubertal development and ovarian histoarchitecture in wistar rat offspring.

Hexavalent chromium (CrVI) is a highly toxic metal and a major environmental pollutant. Several studies indicate that CrVI exposure adversely affects reproductive function. We reported that maternal Cr exposure resulted in Cr accumulation in the reproductive organs of female offsprings. CrVI can cross the placental barrier and also can be passed through breastfeeding. The present investigation aimed to determine the persistent (in utero through puberal period) CrVI exposure-induced toxic effects on the reproductive functions of mother and the offspring. Induction of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. Mother rats exposed to CrVI showed reduced reproductive outcome, while the offsprings showed higher accumulation of Cr in ovary, altered steroid, and peptide hormones. Specific activities of antioxidant enzymes were decreased and associated with increased levels of H2 O2 , and lipid peroxidation. CrVI exposure also damaged the ovarian histoarchitecture in various age groups studied. CrVI exposure also delayed the sexual maturation. Results from the present investigation suggest that CrVI exposure from in utero through puberal period significantly damaged the pubertal development through altered antioxidants, anemia, and altered hormone levels. These changes were associated with damaged ovarian histoarchitecture and extended estrous cycle in developing Wistar rats.

The attitude toward living kidney donation among personnel from units related to donation and transplantation in Spain, Mexico and Cuba.

BACKGROUND: Living kidney donation (LKD) is becoming increasingly necessary as a treatment option for reducing the deficit in transplant organs. Hospital personnel in services related to donation and transplantation play a key role in promoting this kind of donation. OBJECTIVE: To analyze the attitude toward LKD among hospital workers in services related to donation and transplantation in Spain and Latin America. METHODS: Eight hospitals in the "International Collaborative Donor Project" were selected (Spain-Mexico-Cuba). A random sample was taken which was stratified according to the type of service and job category, in transplant-related services. RESULTS: Of the 878 respondents, 90% were in favor of related LKD, and 28% were in favor if the LKD was not related. Attitude was more favorable among Latin Americans workers compared to the Spanish (p=0.014). Other factors associated to attitude included: age (p=0.004); an attitude in favor of deceased donation and living liver donation (p<0.001); and acceptance of a kidney from a donor (p<0.001). CONCLUSIONS: The attitude toward related LKD was very favorable among hospital personnel in units related to the donation and transplantation process in Spain and Latin America, which means that they could contribute to its promotion particularly at the current time when living kidney donation needs to be expanded.

Spanish-Latin American multicenter study of attitudes toward organ donation among personnel from hospital healthcare centers.

INTRODUCTION: Hospital personnel are a group which has an influence on the opinion of the rest of the population about healthcare matters. Any unfavorable attitude of this group would be an obstacle to an increase in organ donation. OBJECTIVE: To analyze the attitude of hospital workers toward the donation of one's own organs in Spanish and Latin American hospitals and to determine the factors affecting this attitude. MATERIAL AND METHOD: Eleven hospitals from the "International Collaborative Donor Project" were selected, 3 in Spain, 5 in Mexico, 2 in Cuba and one in Costa Rica. A random sample was stratified by the type of service and job category. Attitude toward donation and transplantation was assessed using a validated survey. The questionnaire was completed anonymously and was self-administered. STATISTICAL ANALYSIS: Student's t-test, the χ2 test and logistic regression analysis. RESULTS: Of the 2,785 workers surveyed, 822 were from Spain, 1,595 from Mexico, 202 from Cuba and 166 from Costa Rica and 79% (n=2,191) were in favor of deceased organ donation. According to country, 94% (n=189) of Cubans were in favor, compared to 82% (n=1,313) of the Mexicans, 73% (n=121) of the Costa Ricans and 69% (n=568) of the Spanish (P<.001). In the multivariate analysis, the following variables had the most specific weight: 1) originating from Cuba (odds ratio=8.196; P<.001); 2) being a physician (OR= 2.544; P<.001); 3) performing a job related to transplantation (OR = 1.610; P=.005); 4) having discussed the subject of donation and transplantation within the family (OR= 3.690; P<.001); 5) having a partner with a favorable attitude toward donation and transplantation (OR= 3.289; P<.001); 6) a respondent's belief that his or her religion is in favor of donation and transplantation (OR= 3.021; P=.001); 7) not being concerned about the possible mutilation of the body after donation (OR= 2.994; P<.001); 8) the preference for other options apart from burial for treating the body after death (OR= 2.770; P<.001); and 9) acceptance of carrying out an autopsy if one were needed (OR= 2.808; P<.001). CONCLUSIONS: Hospital personnel in Spanish and Latin American healthcare centers had a favorable attitude toward donation, although 21% of respondents were not in favor of donating. This attitude was more favorable among Latin American workers and was very much conditioned by job-related and psychosocial factors.

Evidence for the absence of enzymatic reactions in the glassy state. A case study of xanthophyll cycle pigments in the desiccation-tolerant moss Syntrichia ruralis.

Desiccation-tolerant plants are able to withstand dehydration and resume normal metabolic functions upon rehydration. These plants can be dehydrated until their cytoplasm enters a 'glassy state' in which molecular mobility is severely reduced. In desiccation-tolerant seeds, longevity can be enhanced by drying and lowering storage temperature. In these conditions, they still deteriorate slowly, but it is not known if deteriorative processes include enzyme activity. The storage stability of photosynthetic organisms is less studied, and no reports are available on the glassy state in photosynthetic tissues. Here, the desiccation-tolerant moss Syntrichia ruralis was dehydrated at either 75% or <5% relative humidity, resulting in slow (SD) or rapid desiccation (RD), respectively, and different residual water content of the desiccated tissues. The molecular mobility within dry mosses was assessed through dynamic mechanical thermal analysis, showing that at room temperature only rapidly desiccated samples entered the glassy state, whereas slowly desiccated samples were in a 'rubbery' state. Violaxanthin cycle activity, accumulation of plastoglobules, and reorganization of thylakoids were observed upon SD, but not upon RD. Violaxanthin cycle activity critically depends on the activity of violaxanthin de-epoxidase (VDE). Hence, it is proposed that enzymatic activity occurred in the rubbery state (after SD), and that in the glassy state (after RD) no VDE activity was possible. Furthermore, evidence is provided that zeaxanthin has some role in recovery apparently independent of its role in non-photochemical quenching of chlorophyll fluorescence.

Photoconductivity in the chalcohalide semiconductor, SbSeI: a new candidate for hard radiation detection.

We investigated an antimony chalcohalide compound, SbSeI, as a potential semiconductor material for X-ray and γ-ray detection. SbSeI has a wide band gap of 1.70 eV with a density of 5.80 g/cm(3), and it crystallizes in the orthorhombic Pnma space group with a one-dimensional chain structure comprised of infinite zigzag chains of dimers [Sb2Se4I8]n running along the crystallographic b axis. In this study, we investigate conditions for vertical Bridgman crystal growth using combinations of the peak temperature and temperature gradients as well as translation rate set in a three-zone furnace. SbSeI samples grown at 495 °C peak temperature and 19 °C/cm temperature gradient with 2.5 mm/h translation rate produced a single phase of columnar needlelike crystals aligned along the translational direction of the growth. The ingot sample exhibited an n-type semiconductor with resistivity of ∼10(8) Ω·cm. Photoconductivity measurements on these specimens allowed us to determine mobility-lifetime (µτ) products for electron and hole carriers that were found to be of similar order of magnitude (∼10(-4) cm(2)/V). Further, the SbSeI ingot with well-aligned, one-dimensional columnar needlelike crystals shows an appreciable response of Ag Kα X-ray.