[A deep-learning model for the assessment of coronary heart disease and related risk factors via the evaluation of retinal fundus photographs].

Objective: To develop and validate a deep learning model based on fundus photos for the identification of coronary heart disease (CHD) and associated risk factors. Methods: Subjects aged>18 years with complete clinical examination data from 149 hospitals and medical examination centers in China were included in this retrospective study. Two radiologists, who were not aware of the study design, independently evaluated the coronary angiography images of each subject to make CHD diagnosis. A deep learning model using convolutional neural networks (CNN) was used to label the fundus images according to the presence or absence of CHD, and the model was proportionally divided into training and test sets for model training. The prediction performance of the model was evaluated in the test set using monocular and binocular fundus images respectively. Prediction efficacy of the algorithm for cardiovascular risk factors (e.g., age, systolic blood pressure, gender) and coronary events were evaluated by regression analysis using the area under the receiver operating characteristic curve (AUC) and R2 correlation coefficient. Results: The study retrospectively collected 51 765 fundus images from 25 222 subjects, including 10 255 patients with CHD, and there were 14 419 male subjects in this cohort. Of these, 46 603 fundus images from 22 701 subjects were included in the training set and 5 162 fundus images from 2 521 subjects were included in the test set. In the test set, the deep learning model could accurately predict patients' age with an R2 value of 0.931 (95%CI 0.929-0.933) for monocular photos and 0.938 (95%CI 0.936-0.940) for binocular photos. The AUC values for sex identification from single eye and binocular retinal fundus images were 0.983 (95%CI 0.982-0.984) and 0.988 (95%CI 0.987-0.989), respectively. The AUC value of the model was 0.876 (95%CI 0.874-0.877) with either monocular fundus photographs and AUC value was 0.885 (95%CI 0.884-0.888) with binocular fundus photographs to predict CHD, the sensitivity of the model was 0.894 and specificity was 0.755 with accuracy of 0.714 using binocular fundus photographs for the prediction of CHD. Conclusion: The deep learning model based on fundus photographs performs well in identifying coronary heart disease and assessing related risk factors such as age and sex.

Identification and characterization of the 14-3-3 gene family in switchgrass.

Members of the 14-3-3 family of proteins are conserved regulatory proteins that are widely found in eukaryotes and play crucial roles in diverse physiological processes, including responses to different stresses. Although genome-wide analysis of 14-3-3 proteins has been performed in a few plant species, it has not been performed in switchgrass. In this study, we identified 21 switchgrass 14-3-3 proteins (designated PvGF14a to PvGF14u) and examined genes for improved stress tolerance in this species. A phylogenetic tree was constructed to demonstrate that PvGF14 proteins can be divided into six groups, and that PvGF14 proteins belonging to each class exhibit similar gene structure. A phylogenetic analysis of PvGF14 proteins among switchgrass, Arabidopsis, and rice was conducted. Ten PvGF14 proteins were found to be orthologous to several abiotic stresses, and these were particularly responsive proteins in Arabidopsis and rice. Tissue-specific expression profiles showed that PvGF14a, PvGF14k, PvGF14l, and PvGF14m may play significant roles in the regulation of lignin metabolism, and that PvGF14r may participate in flower development. Taken together, these data suggest that PvGF14 proteins may be involved in various biosynthesis.

Orthogonal design in the optimization of a start codon targeted (SCoT) PCR system in Roegneria kamoji Ohwi.

Roegneria kamoji Ohwi is an excellent forage grass due to its high feeding value and high resistance to some biotic and abiotic stresses. However, the start codon targeted (SCoT) polymorphism has not been conducted on R. kamoji. In this study, an orthogonal L16 (45) design was employed to investigate the effects of five factors (Mg2+, dNTPs, Taq DNA polymerase, primer, and template DNA) on the polymerase chain reaction (PCR) to determine the optimal SCoT-PCR system for R. kamoji. The results showed that the most suitable conditions for SCoT-PCR in R. kamoji included 1.5 mM Mg2+, 0.15 mM dNTPs, 1.0 U Taq DNA polymerase, 0.4 pM primer, and 40 ng template DNA. SCoT primers 39 and 41 were used to verify the stability of the optimal reaction system, and amplification bands obtained from diverse samples were found to be clear, rich, and stable in polymorphisms, indicating that this reaction system can be used for SCoT-PCR analysis of R. kamoji. We have developed a simple and rapid way to study the mutual effects of factors and to obtain positive results through the use of an orthogonal design L16 (45) to optimize the SCoT-PCR system. This method may provide basic information for molecular marker-assisted breeding and analyses of genetic diversity in R. kamoji.

Assessment of genetic diversity of bermudagrass germplasm from southwest China and Africa by using AFLP markers.

Cynodon dactylon (L.) Pers. var. dactylon (common bermudagrass) is widely distributed geographically between approximately 45°N and 45°S latitude, penetrating to approximately 53°N latitude in Europe. The extensive variation of morphological and adaptive characteristics of the taxon has been substantially documented, but information is lacking on DNA molecular variation in geographically disparate forms. The genetic diversity of 51 wild accessions of bermudagrass from southwest China (Sichuan, Chongqing, Yunnan, Guizhou, and Tibet) and 8 African bermudagrass was analyzed using amplified fragment length polymorphism molecular markers. A total of 670 polymorphic bands were detected with 11 primer combinations, of which 663 (98.74%) bands were found to be polymorphic. The genetic similarity among the accessions ranged from 0.64-0.96 with an average of 0.78. All 59 wild accessions were clustered into 5 eco-geographic groups, and nearly all accessions from the same area were classified into the same group and were found to be associated with their geographical distributions. Therefore, complex geographical and ecological environments are important factors for the genetic structure and geographical distribution of C. dactylon.

Optimization of SCoT-PCR reaction system in Dactylis glomerata by orthogonal design.

The effects of 5 factors (template DNA, Mg(2+), dNTPs, Taq DNA polymerase, and primer) on the polymerase chain reaction (PCR) were investigated to optimize the start codon targeted polymor-phism (SCoT)-PCR system of Dactylis glomerata L., using an orthogo-nal design L16 (4(5)). A suitable SCoT-PCR system for D. glomerata was established; the 20 µL reaction volume contained 3.0 mM Mg(2+), 0.2 mM dNTPs, 1.0 U Taq DNA polymerase, 0.2 µM primer, 20 ng tem-plate DNA, and 2 µL 10X buffer. Each factor had a different effect on the amplification reaction, and the concentration of dNTPs had the larg-est effect on the SCoT-PCR system. We tested 10 orchardgrass samples to determine and verify the stability of the reaction system. The results showed that amplified bands from diverse materials were clear, stable, and rich in polymorphisms, indicating that the optimized system was very stable.

Morphological and genetic characteristics of hybrid combinations of Dactylis glomerata.

Six F1 populations derived from crosses among 4 orchardgrass (Dactylis glomerata L.) cultivars were studied by morphological and simple sequence repeat molecular markers to test for hybrid vigor and a correlation between genetic distance and heterosis. Heterosis was observed for days to length of culm, leaf traits, tiller numbers, etc. Significant differences between obverse and inverse crosses were found for eleven traits. A cytoplasmic effect existed for the agronomic traits considered in this study. The correlations between genetic distance and heterosis were investigated by analyzing the performance of 3 crosses. The results showed that genetic distance was significantly correlated with tiller number (r = 0.834) and negatively correlated with length of culm (r = -0.889). However, there was no significant correlation with heterosis for the other traits, including yield; the correlation coefficient were too small to allow prediction of orchardgrass heterosis from the parental genetics.

Analysis of diversity and relationships among orchardgrass (Dactylis glomerata L.) accessions using start codon-targeted markers.

Orchardgrass, or cocksfoot, is an important perennial forage grass worldwide. The comprehensive understanding of orchardgrass accessions will benefit germplasm collection and breeding progress, and it will enhance efforts to improve forage yield and quality. Therefore, 24 novel, simple, polymorphic, and reliable start codon-targeted (SCoT) markers were used to analyze the diversity and genetic relationships among 95 orchardgrass accessions. In total, 273 polymorphic bands were detected with an average of 11.4 bands per primer. The average polymorphic rate for the species was 83.4%, suggesting a high discriminating ability of the SCoT technique for orchardgrass. The molecular variance analysis revealed that 69.13 and 30.87% of variation resided within and among groups, respectively, demonstrating that the orchardgrass germplasms had a higher level of genetic diversity within groups than among geographical regions and distributions. The distinct geographical divergence of orchardgrass was revealed between North America and Oceania. The unweighted pair-group method with arithmetic mean dendrogram revealed a separation of 7 main clusters between 95 accessions according to the geographical origin. Furthermore, each cluster was divided into subgroups mainly according to the origin of its state. The genetic divergence of orchardgrass might be influenced by the ecogeographical conditions, climatic types, breeding systems and gene flow with variations in cultures, bird migration, and breeder selection. These results could facilitate orchardgrass germplasm collection, management, and breeding worldwide.

Genetic diversity and relationship of chicory (Cichorium intybus L.) using sequence-related amplified polymorphism markers.

Chicory is a crop with economically important roles and is cultivated worldwide. The genetic diversity and relationship of 80 accessions of chicories and endives were evaluated by sequence-related amplified polymorphism (SRAP) markers to provide a theoretical basis for future breeding programs in China. The polymorphic rate was 96.83%, and the average polymorphic information content was 0.323, suggesting the rich genetic diversity of chicory. The genetic diversity degree of chicory was higher (GS = 0.677) than that of endive (GS = 0.701). The accessions with the highest genetic diversity (effective number of alleles, NE = 1.609; Nei's genetic diversity, H = 0.372; Shannon information index, I = 0.556) were from Italy. The richest genetic diversity was revealed in a chicory line (NE = 1.478, H = 0.289, I = 0.443) among the 3 types (line, wild, and cultivar). The chicory genetic structure of 8 geographical groups showed that the genetic differentiation coefficient (GST) was 14.20% and the number of immigrants per generation (Nm) was 3.020. A GST of 6.80% and an Nm of 6.853 were obtained from different types. This observation suggests that these chicory lines, especially those from the Mediterranean region, have potential for providing rich genetic resources for further breeding programs, that the chicory genetic structure among different countries obviously differs with a certain amount of gene flow, and that SRAP markers could be applied to analyze genetic relationships and classifications of Cichorium intybus and C. endivia.

Genetic diversity and relationships in cultivars of Lolium multiflorum Lam. using sequence-related amplified polymorphism markers.

Sequence-related amplified polymorphism (SRAP) markers were used to analyze and estimate the genetic variability, level of diversity, and relationships among 20 cultivars and strains of annual ryegrass (Lolium multiflorum Lam.). Eighteen SRAP primer combinations generated 334 amplification bands, of which 298 were polymorphic. The polymorphism information content ranged from 0.4715 (me10 + em1) to 0.5000 (me5 + em7), with an average of 0.4921. The genetic similarity coefficient ranged from 0.4304 to 0.8529, and coefficients between 0.65 and 0.90 accounted for 90.00%. The cluster analysis separated the accessions into five groups partly according to their germplasm resource origins.

Genetic diversity and relationships among accessions of five crested wheatgrass species (Poaceae: Agropyron) based on gliadin analysis.

Agropyron Gaertn. is the most important genus in Triticeae (Poaceae), which includes many forage grasses with high economic value. The genetic diversity and relationships of 36 accessions from five crested wheatgrass species were analyzed by gliadin markers. A total of 54 product bands were detected after acid polyacrylamide gel electrophoresis (A-PAGE), of which 100% were polymorphic. The genetic similarity coefficient based on Nei-Li's method ranged from 0.065 to 0.755 with an average of 0.451. The Shannon diversity information index showed that there was a high level of genetic diversity among the accessions. An unweighted pair group method with arithmetic average (UPGMA) dendrogram was constructed based on the Nei-Li's genetic similarity coefficients, which showed the phylogenetic relationships among accessions of different species. Analysis of molecular variance (AMOVA) showed that the proportion of variance explained by inter- and intraspecific variance was 9.34 and 90.66%, respectively, which revealed that the genetic variations within species were higher than the variations among species. Based on pairwise genetic distances (ΦST) among species, the cluster analysis indicated that A. mongolicum had a low-affinity relationship with other species, while A. fragile showed a close relationship with A. cristatum ssp pectinatum. Finally, the implications of the results for the taxonomy of Agropyron were discussed.

Genetic relationships between Lolium (Poaceae) species revealed by RAPD markers.

The genus Lolium is one of the most important groupings of temperate forage grasses, including about eight recognized species that are native to some temperate and subtropical regions of the northern hemisphere. We examined genetic relationships among 18 accessions representing all Lolium species using RAPD markers. Among 50 random primers that we screened, 13 gave reproducible amplification banding patterns. Each of these 13 primers generated 19-43 scorable fragments. A total of 367 RAPD fragments were detected, of which 95.9% were polymorphic across all the Lolium accessions. Dice's coefficient of dissimilarity ranged from 0.016 to 0.622, which is indicative of substantial genetic variations in these Lolium accessions. A neighbor-joining cluster analysis, with bootstrap permutation, produced an unrooted dendrogram, which grouped 18 accessions into two main clades, supporting high bootstrap values (98 and 96%). The first clade included the self-pollinated species, L. persicum, L. temulentum, L. remotum, and L. subulatum. The cross-pollinated species, i.e., L. multiflorum, L. perenne, L. rigidum, and L. canariense, composed the second clade, in which L. canariense formed a distinct subclade, indicating its higher genetic separation from other allogamous species. The value of r = 0.97 in the Mantel test for cophenetic correlation applied to the cluster analysis indicated the high degree of fit of the accessions to a group. A principal coordinate analysis, whose first three coordinates explained 72.6% of the variation, showed similar groupings as in the cluster analysis. The genetic relationships estimated by the polymorphism of RAPD markers are basically in agreement with those previously inferred with other genetic markers.

Identification of orchardgrass (Dactylis glomerata L.) cultivars by using simple sequence repeat markers.

The accurate identification of orchardgrass (Dactylis glomerata L.) cultivars is necessary to ensure purity for consumers, the effective utilization of cultivars, and to protect the intellectual property for breeders. Therefore, this study aimed to use SSR to construct DNA fingerprinting of orchardgrass cultivars. The genetic diversity of 32 orchardgrass cultivars originated from 21 countries, but grown in China, was assessed using a set of 29 SSR markers distributed across 9 linkage groups of the orchardgrass genome. A total of 229 bands were detected, with an average of 7.9 bands per marker. The average polymorphic rate for the species was 92.1%. The polymorphism information content ranged from 0.771 to 0.893. The genetic similarity ranged from 0.55 to 0.84, which confirmed a high level of genetic diversity among orchardgrass cultivars. The unweighted pair-group method, in combination with the arithmetic mean algorithm (UPGMA) dendrogram and principal coordinate analysis, showed a separation of 6 major clusters among 32 cultivars. The number of distinguishable cultivars ranged from 3 to 23, with an average of 12.1 per primer. Moreover, 11 bands that showed stable and repeatable SSR patterns were amplified by A01E14, A01K14, and D02K13. These bands were used to develop the DNA fingerprints for 32 orchardgrass cultivars. In the DNA fingerprints constructed, each cultivar had a unique fingerprinting pattern that was easily distinguished from the others. These results indicate that the SSR marker was polymorphic, and reliable for use in potential large-scale DNA fingerprinting of orchardgrass cultivars.

Genetic variation and comparison of orchardgrass (Dactylis glomerata L.) cultivars and wild accessions as revealed by SSR markers.

Orchardgrass is a highly variable, perennial forage grass that is cultivated throughout temperate and subtropical regions of the world. Despite its economic importance, the genetic relationship and distance among and within cultivars are largely unknown but would be of great interest for breeding programs. We investigated the molecular variation and structure of cultivar populations, compared the level of genetic diversity among cultivars (Baoxing, Anba, Bote, and Kaimo), subspecies (Dactylis glomerata ssp Woronowii) and advanced breeding line (YA02-116) to determine whether there is still sufficient genetic diversity within presently used cultivars for future breeding progress in China. Twenty individuals were analyzed from each of six accessions using SSR markers; 114 easily scored bands were generated from 15 SSR primer pairs, with an average of 7.6 alleles per locus. The polymorphic rate was 100% among the 120 individuals, reflecting a high degree of genetic diversity. Among the six accessions, the highest genetic diversity was observed in Kaimo (H = 0.2518; I = 0.3916; P = 87.3%) and 02-116 had a lower level of genetic diversity (H = 0.1806; I = 0.2788; P = 58.73%) compared with other cultivars tested. An of molecular variance revealed a much larger genetic variation within accessions (65%) than between them (35%). This observation suggests that these cultivars have potential for providing rich genetic resource for further breeding program. Furthermore, the study also indicated that Chinese orchardgrass breeding has involved strong selection for adaptation to forage production, which may result in restricted genetic base of orchardgrass cultivar.

Molecular diversity and population structure of the forage grass Hemarthria compressa (Poaceae) in south China based on SRAP markers.

Hemarthria compressa is one of the most important and widely utilized forage crops in south China, owing to its high forage yield and capability of adaptation to hot and humid conditions. We examined the population structure and genetic variation within and among 12 populations of H. compressa in south China using sequence-related amplified polymorphism (SRAP) markers. High genetic diversity was found in these samples [percentage polymorphic bands (PPB) = 82.21%, Shannon's diversity index (I) = 0.352]. However, there was relatively low level of genetic diversity at the population level (PPB = 29.17%, I = 0.155). A high degree of genetic differentiation among populations was detected based on other measures and molecular markers (Nei's genetic diversity analysis: G(ST) = 54.19%; AMOVA analysis: F(ST) = 53.35%). The SRAP markers were found to be more efficient than ISSR markers for evaluating population diversity. Based on these findings, we propose changes in sampling strategies for appraising and utilizing the genetic resources of this species.

Identifying differentially expressed genes under heat stress and developing molecular markers in orchardgrass (Dactylis glomerata L.) through transcriptome analysis.

Orchardgrass (Dactylis glomerata L.) is a long-lived, cool-season forage grass that is commonly used for hay production. Despite its economic importance, orchardgrass genome remains relatively unexplored. In this study, we used Illumina RNA sequencing to identify gene-associated molecular markers, including simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), as well as heat stress-induced differentially expressed genes (DEGs) in two orchardgrass genotypes, 'Baoxing' (heat resistant) and '01998' (heat susceptible). Approximately 163 million high-quality trimmed reads were generated from 207 million raw reads using the Illumina HiSeq 2000 platform. A total of 126,846 unigenes were obtained after de novo assembly of the trimmed reads, and 40,078 unigenes were identified as coding sequences (CDSs). Based on the assembled unigenes, 669,300 high-quality SNPs, including 416,099 transitions and 257,736 transversions, were contained in 75,875 unigenes. In addition, a total of 8475 microsatellites were detected in 7764 unigenes. When placed under heat stress, the total number of DEGs in 'Baoxing' (3527) was higher than in '01998' (2649), indicating that in comparison with heat-susceptible '01998', heat-resistant 'Baoxing' seems to have more unigenes that respond to heat stress. The high-throughput transcriptome sequencing of orchardgrass under heat stress provides useful information for gene identification and for the development of SNP and SSR molecular markers. The comparison of DEGs under different periods of heat stress allowed us to identify a wealth of candidate DEGs that can be further analysed in order to determine the genetic mechanisms underlying heat tolerance in orchardgrass.

Radiological manifestations of pulmonary tuberculosis in patients subjected to anti-TNF-α treatment.

SETTING: The risk of pulmonary tuberculosis (PTB) may increase with increased use of anti-tumour necrosis factor (TNF) treatment in inflammatory arthritis. OBJECTIVE: To evaluate the impact of anti-TNF treatment on radiological manifestations of PTB. METHOD: Between January 2007 and December 2012, the chest radiographs (CXRs) of 23 consecutive patients with newly diagnosed PTB who underwent anti-TNF treatment were studied. Chest computed tomography (CT) images were available for 14. To compare the radiological features of PTB, the CXRs of 46 immunocompetent PTB patients with similar demographics were studied as controls, of whom 34 underwent chest CT. Two radiologists and one chest physician reviewed the chest images independently. RESULTS: Compared with the controls, fibronodular lesions were less common on CXR in the anti-TNF group (P < 0.001). In contrast, lymphadenopathy (P < 0.001), pleural effusion (P = 0.015) and pericardial effusion (P = 0.02) were more common, while tree-in-bud appearance (P = 0.017) was less commonly depicted on chest CT in the anti-TNF group. Although there was no significant difference in zonal predilection and laterality of the lesions between the two groups, diffuse lesions (P = 0.004) on chest CT scans were more frequent in the anti-TNF group. CONCLUSION: Unusual presentations of PTB were more common in the CXRs and/or CT scans of patients who underwent anti-TNF treatment.

Photosystem II function and herbicide binding sites during photoinhibition of spinach chloroplasts in-vivo and in-vitro.

The time courses of some Photosystem II (PS II) parameters have been monitored during in-vivo and in-vitro photoinhibition of spinach chloroplasts, at room temperature and at 10 °C or 0 °C. Exposing leaf discs of low-light grown spinach at 25 °C to high light led to photoinhibition of chloroplasts in-vivo as manifested by a parallel decrease in the number of functional PS II centres, the variable chlorophyll fluorescence at 77K (F v /F m ), and the number of atrazine-binding sites. When the photoinhibitory treatment was given at 10 °C, the former two parameters declined in parallel but the loss of atrazine-binding sites occurred more slowly and to a lesser extent. During in-vitro photoinhibition of chloroplast thylakoids at 25 °C, the loss of functional PS II centres proceeded slightly more rapidly than the loss of atrazine-binding sites, and this difference in rate was further increased when the thylakoids were photoinhibited at 0 °C. During the recovery phase of leaf discs (up to 9 h) the increases in F v /F m preceded that of the number of functional PS II centres, while only a further decline in the number of atrazine-binding sites was observed. The recovery of variable chlorophyll fluorescence and the concentration of functional PS II centres occurred more rapidly at 25 °C than at 10 °C. These results suggest that the photoinhibition of PS II function is a relatively temperature-independent early photochemical event, whereas the changes in the concentration of herbicide-binding sites appear to be a more complex biochemical process which can occur with a delayed time course.

Development of a statistical model for the formation of poly [acryloyl hydroxyethyl starch] microspheres.

PURPOSE: To develop a mathematical model for predicting the molecular weight between crosslinks, Mc, of poly[Acryloyl Hydroxyethyl Starch] (Ac-HES) microspheres system and to identify and evaluate the key microsphere preparation parameters which affect the Mc of the formed microsphere structure based on the developed model. METHODS: Link probability generating functions (LPGFs) based on the classical branching theory were used to derive a model for the calculation of Mc for the Ac-HES system. Based on the developed model, simulation was made to study the effects of the microsphere preparation variables on Mc of the formed microspheres. The process variables were the degree of derivatization (DD) of the Ac-HES, the molar ratio (MR) of the Ac-HES to acrylamide monomer, the fractional conversion of the unsaturation (alpha), the initiator efficiency (f), the molar concentration of initiator (I), the fraction of intramolecular cyclization (c), and the total weight of the reactable monomer and polymer (s). RESULTS: A model to describe the crosslinking reaction of Ac-HES system and predict Mc was developed. Simulation based on the model showed that Mc decreased as alpha increased and reached a limiting value before total conversion. At constant alpha, Mc initially decreased with MR to a minimum and then increased with MR; while Mc decreased monotonically with DD. I and c affected Mc only at very low alpha and changes in s and f had no effect on Mc. CONCLUSIONS: Simulation based on the model suggested that the most important microsphere preparation parameters influencing Mc of the Ac-HES system are the number of functional groups on the Ac-HES (DD) and the stoichiometry (MR) of the crosslinking reaction.

Evaluation of a statistical model for the formation of poly [acryloyl hydroxyethyl starch] microspheres.

PURPOSE: To characterize the network structure of Poly(Acryloyl Hydroxyethyl Starch) (Ac-HES) microspheres and test the theoretical model and the hypothesis that the rate of swelling of microspheres is inversely related to the extent of crosslinking. METHODS: Microspheres were prepared with varying degrees of derivatization (DD) and molar ratios (MR) and subjected to the characterization of matrix structure by dynamic and equilibrium swelling studies utilizing direct microscopic observation and the Flory-Rehner equation. The dependence of average molecular weight between crosslinking Mc, on DD and MR were compared to test the validity of the model. RESULTS: Study of the dependence of Mc on the microspheres preparation parameters, DD and MR, showed that at constant MR, the Mc decreased with DD, while at constant DD, the Mc initially decreased with MR to a minimum, and then increased with MR, complying with the model prediction. Dynamic swelling of microspheres showed a monotonical increase to equilibrium size featured by two time variables, Tp and Teq, that were dependent on Mc; this permitted a conceptual view of the general structure of the Ac-HES microspheres. The Mc, which was more accurately determined by the weight method (as opposed to volume method), was independent of the size of microspheres although there was evidence of variation among particles within a batch. CONCLUSIONS: The results validated the model in describing the polymerization/crosslinking reaction of the Ac-HES microsphere system and suggested that Mc is the principal factor in controlling release.

Measured conversion efficiencies of P45, paraterphenyl, tetraphenyl butadiene, and sodium salicylate phosphors in the soft-x-ray wavelength range.

The measured conversion efficiencies at 9.89, 23.6, 44.7, and 160 Å of P45 phosphor screens, as well as those of paraterphenyl, tetraphenyl butadiene, and sodium salicylate at 9.89, 44.7, and 67.6 Å, are presented. The conversion efficiency is defined as the ratio of photoelectrons ejected from the photocathode of a visible detector, which are excited by the scintillated photons that are emitted from the phosphor in a solid angle of 2π, to the number of soft-x-ray photons incident on the phosphor. The effect of the phosphor's thickness on the conversion efficiency was studied. The P45 phosphor converts the soft-x-ray photon (10-200 Å) into an order of magnitude more visible photons than the low-Z phosphors. The P45 phosphor screen used in conjunction with a photomultiplier tube offers a soft-x-ray photodetector with a conversion efficiency that ranges from 0.5 at 160 Å to 12 at 9.89 Å and a high electronic gain.