Reflectance Spectroscopy as a Novel Tool for Thickness Measurements of Paint Layers.

A major challenge in heritage science is the non-invasive cross-sectional analysis of paintings. When low-energy probes are used, the presence of opaque media can significantly hinder the penetration of incident radiation, as well as the collection of the backscattered signal. Currently, no technique is capable of uniquely and noninvasively measuring the micrometric thickness of heterogeneous materials, such as pictorial layers, for any painting material. The aim of this work was to explore the possibility of extracting stratigraphic information from reflectance spectra obtained by diffuse reflectance spectroscopy (DRS). We tested the proposed approach on single layers of ten pure acrylic paints. The chemical composition of each paint was first characterised by micro-Raman and laser-induced breakdown spectroscopies. The spectral behaviour was analysed by both Fibre Optics Reflectance Spectroscopy (FORS) and Vis-NIR multispectral reflectance imaging. We showed that there is a clear correlation between the spectral response of acrylic paint layers and their micrometric thickness, which was previously measured by Optical Coherence Tomography (OCT). Based on significant spectral features, exponential functions of reflectance vs. thickness were obtained for each paint, which can be used as calibration curves for thickness measurements. To the best of our knowledge, similar approaches for cross-sectional measurements of paint layers have never been tested.

Form and magnetic birefringence in undulated Permalloy/PET films.

We report the measurement of form and magnetic birefringence in Permalloy (Ni80Fe20) films grown on rippled Poly(Ethylene Terephthalate), PET, substrates. Prior to Permalloy deposition, Laser Induced Periodic Surface Structures (LIPSS) were generated on the polymeric substrate by a nanosecond laser beam, developing an ordered rippled nanostructure. Due to their high transparency factor, we could investigate the behavior of linear polarized light transmitting at normal incidence on Permalloy/PET sample. The results show the existence of an optical axis parallel to the ripples direction, which yields an strong form birefringence effect arising from the laser patterning. Concerning the Permalloy thin film, the study of its in-plane magnetization was carried out measuring the Voigt magnetooptical effect. The obtained data in our samples reveal the appearance of two different mechanisms to reverse the magnetization, as the external magnetic field is parallel or perpendicular to the ripples direction. Accordingly, the transmitted light shows a magnetic birefringence depending on the relative orientation between the ripple direction, i.e. the optical axis of the LIPSS, and the in-plane magnetization of the Permalloy film.

Patterning Conjugated Polymers by Laser: Synergy of Nanostructure Formation in the All-Polymer Heterojunction P3HT/PCDTBT.

In this work we report a broad scenario for the patterning of semiconducting polymers by laser-induced periodic surface structures (LIPSS). Based on the LIPSS formation in the semicrystalline poly(3-hexylthiophene) (P3HT), we have extended the LIPSS fabrication to an essentially amorphous semiconducting polymer like poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT). This polymer shows a good quality and well-ordered nanostructures not only at the 532 nm laser wavelength, as in the case of P3HT, but also at 266 nm providing gratings with smaller pitch. In addition, we have proven the feasibility of fabricating LIPSS in the P3HT/PCDTBT (1:1) blend, which can be considered as a model bulk-heterojunction for all-polymer solar cells. In spite of the heterogeneous roughness, due to phase separation in the blend, both P3HT and PCDTBT domains present well-defined LIPSS as well as a synergy for both components in the blend when irradiating at wavelengths of 532 and 266 nm. Both, P3HT and PCDTBT in the blend require lower fluence and less pulses in order to optimize LIPSS morphology than in the case of irradiating the homopolymers separately. Near edge X-ray absorption fine structure and Raman spectroscopy reveal a good chemical stability of both components in the blend thin films during LIPSS formation. In addition, scanning transmission X-ray spectro-microscopy shows that the mechanisms of LIPSS formation do not induce a further phase segregation neither a mixture of the components. Conducting atomic force microscopy reveals a heterogeneous electrical conductivity for the irradiated homopolymer and for the blend thin films, showing higher electrical conduction in the trenches than in the ridge regions of the LIPSS.

Ablation dynamics of Co/ZnS targets under double pulse femtosecond laser irradiation.

Femtosecond lasers, used as tools to investigate the ablation dynamics of solids, can help to develop strategies to control the deposition of nanomaterials by pulsed laser ablation. In this work, Co/ZnS targets, potential candidates for the synthesis of diluted magnetic semiconductor materials, are irradiated by sequences of two femtosecond laser pulses delayed in the picosecond time scale. The ionic composition of the ablation plasma and the dependence of the ion signals on the interpulse delay and relative fluence are determined by time-of-flight mass spectrometry. The results show that, when pulses of different fluence are used, highly asymmetric ion yields are obtained, with more intense ion signals detected when the lower fluence pulse is temporally ahead. The comparison between asymmetric and equal fluence double pulse ablation dynamics provides some understanding of the different processes that modify the properties of the layer irradiated by the first pulse and of the mechanisms affecting the coupling of the delayed pulse into the material. The final outcome of the double pulse irradiation is characterized through the analysis of the deposits produced upon ablation.

In situ monitoring of laser-induced periodic surface structures formation on polymer films by grazing incidence small-angle X-ray scattering.

The formation of laser-induced periodic surface structures (LIPSS) on model spin-coated polymer films has been followed in situ by grazing incidence small-angle X-ray scattering (GISAXS) using synchrotron radiation. The samples were irradiated at different repetition rates ranging from 1 up to 10 Hz by using the fourth harmonic of a Nd:YAG laser (266 nm) with pulses of 8 ns. Simultaneously, GISAXS patterns were acquired during laser irradiation. The variation of both the GISAXS signal with the number of pulses and the LIPSS period with laser irradiation time is revealing key kinetic aspects of the nanostructure formation process. By considering LIPSS as one-dimensional paracrystalline lattice and using a correlation found between the paracrystalline disorder parameter, g, and the number of reflections observed in the GISAXS patterns, the variation of the structural order of LIPSS can be assessed. The role of the laser repetition rate in the nanostructure formation has been clarified. For high pulse repetition rates (i.e., 10 Hz), LIPSS evolve in time to reach the expected period matching the wavelength of the irradiating laser. For lower pulse repetition rates LIPSS formation is less effective, and the period of the ripples never reaches the wavelength value. Results support and provide information on the existence of a feedback mechanism for LIPSS formation in polymer films.

Bleeding risks are higher in children versus adults given prophylactic platelet transfusions for treatment-induced hypoproliferative thrombocytopenia.

Age-group analyses were conducted of patients in the prophylactic platelet dose trial (PLADO), which evaluated the relation between platelet dose per transfusion and bleeding. Hospitalized patients with treatment-induced hypoproliferative thrombocytopenia were randomly assigned to 1 of 3 platelet doses: 1.1 × 10(11), 2.2 × 10(11), or 4.4 × 10(11) platelets/m(2) per transfusion, given for morning counts of ≤ 10 000 platelets/µL. Daily hemostatic assessments were performed. The primary end point (percentage of patients who developed grade 2 or higher World Health Organization bleeding) was evaluated in 198 children (0-18 years) and 1044 adults. Although platelet dose did not predict bleeding for any age group, children overall had a significantly higher risk of grade 2 or higher bleeding than adults (86%, 88%, 77% vs 67% of patients aged 0-5 years, 6-12 years, 13-18 years, vs adults, respectively) and more days with grade 2 or higher bleeding (median, 3 days in each pediatric group vs 1 day in adults; P < .001). The effect of age on bleeding differed by disease treatment category and was most pronounced among autologous transplant recipients. Pediatric subjects were at higher risk of bleeding over a wide range of platelet counts, indicating that their excess bleeding risk may be because of factors other than platelet counts.

Physicochemical modifications accompanying UV laser induced surface structures on poly(ethylene terephthalate) and their effect on adhesion of mesenchymal cells.

This work reports on the formation of different types of structures on the surface of polymer films upon UV laser irradiation. Poly(ethylene terephthalate) was irradiated with nanosecond UV pulses at 193 and 266 nm. The polarization of the laser beam and the irradiation angle of incidence were varied, giving rise to laser induced surface structures with different shapes and periodicities. The irradiated surfaces were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via micro-Raman and fluorescence spectroscopies. Contact angle measurements were performed with different liquids, and the results evaluated in terms of surface free energy components. Finally, in order to test the influence of surface properties for a potential application, the modified surfaces were used for mesenchymal stem cell culture assays and the effect of nanostructure and surface chemistry on cell adhesion was evaluated.

Assessment of femtosecond laser induced periodic surface structures on polymer films.

In this work we present the formation of laser induced periodic surface structures (LIPSS) on spin-coated thin films of several model aromatic polymers including poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly carbonate bis-phenol A upon irradiation with femtosecond pulses of 795 and 265 nm at fluences well below the ablation threshold. LIPSS are formed with period lengths similar to the laser wavelength and parallel to the direction of the laser polarization vector. Formation of LIPSS upon IR irradiation at 795 nm, a wavelength at which the polymers absorb weakly, contrasts with the absence of LIPSS in this spectral range upon irradiation with nanosecond pulses. Real and reciprocal space characterization of LIPSS obtained by Atomic Force Microscopy (AFM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS), respectively, yields well correlated morphological information. Comparison of experimental and simulated GISAXS patterns suggests that LIPSS can be suitably described considering a quasi-one-dimensional paracrystalline lattice and that irradiation parameters have an influence on the order of such a lattice. Fluorescence measurements, after laser irradiation, provide indirect information about dynamics and structure of the polymer at the molecular level. Our results indicate that the LIPSS are formed by interference of the incident and surface scattered waves. As a result of this process, heating of the polymer surface above its glass transition temperature takes place enabling LIPSS formation.

Comparison of high-order harmonic generation in uracil and thymine ablation plumes.

We present studies of high-order harmonic generation (HHG) in laser ablation plumes of the ribonucleic acid nucleobase uracil and its deoxyribonucleic acid counterpart thymine. Harmonics were generated using 780 nm, 30 fs and 1300 nm, 40 fs radiation upon ablation with 1064 nm, 10 ns or 780 nm, 160 ps pulses. Strong HHG signals were observed from uracil plumes with harmonics emitted with photon energies >55 eV. Results obtained in uracil plumes were compared with those from thymine, which did not yield signs of harmonic generation. The ablation plumes of the two compounds were examined by collection of the ablation debris on a silicon substrate placed in close proximity to the target and by time-of-flight mass spectrometry. From this evidence we conclude that the differences in HHG signal are due to the different fragmentation dynamics of the molecules in the plasma plume. These studies constitute the first attempt to analyse differences in structural properties of complex molecules through plasma ablation-induced HHG spectroscopy.

Cytochrome P450 2D6 polymorphisms and predicted opioid metabolism in African American children with sickle cell disease.

The opioid medications codeine and hydrocodone, commonly prescribed in sickle cell disease (SCD), require metabolic conversion by cytochrome P450 2D6 (CYP2D6) to morphine and hydromorphone, respectively, to exert their analgesic effects. The CYP2D6 gene is highly polymorphic, with variant alleles that result in decreased, absent, or ultrarapid enzyme activity. Seventy-five children with SCD were tested for CYP2D6 polymorphisms, and metabolic phenotypes were inferred from the genotypes. The most common variant alleles were CYP2D6*2 (normal activity, 28.7%), CYP2D6*17 (reduced activity, 17.3%), CYP2D6*5 (gene deletion, 8.7%), and CYP2D6*4 (absent function, 8.0%). Normal/extensive metabolizer genotypes were found in 28/75 (37.5%), intermediate metabolism in 33/75 (44.0%), poor metabolism in 4/75 (5.3%), ultrarapid metabolism in 3/75 (4.0%), indeterminate in 6/75 (8.0%). Allele frequencies did not vary significantly among different hemoglobin genotypes. Identification of variant CYP2D6 genotypes may identify individuals with altered metabolism and therefore altered analgesic response to codeine and hydrocodone, thus providing a personalized medicine approach to treatment of pain in SCD. Further pharmacokinetic and pharmacodynamic studies are needed to define the relationship of CYP2D6 and other gene polymorphisms to individual opioid effect in SCD.

Gold coatings on polymer laser induced periodic surface structures: assessment as substrates for surface-enhanced Raman scattering.

We report on the fabrication of gold coated nanostructured polymer thin films and on their characterization as substrates for surface enhanced Raman spectroscopy (SERS). Laser induced periodic surface structures (LIPSS) were obtained on thin polymer films of poly(trimethylene terephthalate) (PTT) upon laser irradiation with the fourth harmonic of a Nd:YAG laser (266 nm, pulse duration 6 ns) resulting in a period close to the incident wavelength. The nanostructured polymer substrates were coated with a nanoparticle assembled gold layer by pulsed laser deposition using the fifth harmonic of a Nd:YAG laser (213 nm, pulse duration 15 ns). Different deposition times resulted in thicknesses from a few nanometres up to several tens of nanometres. Analysis by atomic force microscopy and grazing incident small angle X-ray scattering showed that gold coating preserved the LIPSS relief. The capabilities of the produced nanostructures as substrates for SERS have been investigated using benzenethiol as a test molecule. The SERS signal is substantially larger than that observed for a gold-coated flat substrate. Advantages of this new type of SERS substrates are discussed.

Assessment and formation mechanism of laser-induced periodic surface structures on polymer spin-coated films in real and reciprocal space.

In this work we evaluate the potential of grazing incidence X-ray scattering techniques in the investigation of laser-induced periodic surface structures (LIPSSs) in a series of strongly absorbing model spin-coated polymer films which are amorphous, such as poly(ethylene terephthalate), poly(trimethylene terephthalate), and poly(carbonate bisphenol A), and in a weaker absorbing polymer, such as semicrystalline poly(vinylidene fluoride), over a narrow range of fluences. Irradiation was performed with pulses of 6 ns at 266 nm, and LIPSSs with period lengths similar to the laser wavelength and parallel to the laser polarization direction are formed by devitrification of the film surface at temperatures above the characteristic glass transition temperature of the polymers. No crystallization of the surface is induced by laser irradiation, and crystallinity of the material prevents LIPSS formation. The structural information obtained by both atomic force microscopy and grazing incidence small-angle X-ray scattering (GISAXS) correlates satisfactorily. Comparison of experimental and simulated GISAXS patterns suggests that LIPSSs can be well described considering a quasi-one-dimensional paracrystalline lattice and that irradiation parameters have an influence on the order of such a lattice.

UV laser removal of varnish on tempera paints with nanosecond and femtosecond pulses.

Two laser cleaning approaches based on ablation by ultraviolet laser pulses of femtosecond (fs) and nanosecond (ns) durations for the removal of shellac varnish from egg-yolk based tempera paints are investigated. Laser irradiation effects, induced on the varnish layer and on the underlying temperas by multiple pulses in the fs domain at 398 and 265 nm and single pulses in the ns domain at 213 nm, were examined following a spectroanalytical approach. By using optical microscopy, colorimetry and laser induced fluorescence it was found that irradiation of the varnished temperas with fs pulses changes the texture of the varnish surface and results in degradation of the underlying coloured paint. In contrast, operating with pulses of 15 ns at the highly absorbed wavelength of 213 nm, controlled micrometric layer removal of the varnish is possible without noticeable modification of the coloured temperas. These results widen the choice of laser conditions for painting restoration.

Lack of Synergy Between ß-Agonist Treatment and a Blockage of Sarcoplasmic Calcium Flow in a Rat Cancer Cachexia Model.

BACKGROUND: During cancer cachexia, both skeletal muscle and adipose tissue losses take place. The use of ß2-agonists, formoterol in particular, has proven to be very successful in the treatment of the syndrome in pre-clinical models. The object of the present research was to study the effects of a combination of formoterol and dantrolene, an inhibitor of the ryanodine receptor 1 (RyR1), on body weight loss and cachexia in tumour-bearing animals. METHODS: Rats were separated into two groups: controls (C) and tumour bearing (TB). TB group was further subdivided into four groups: untreated (saline as a vehicle), treated with Formoterol (TF) (0,3 mg/kg body weight in saline, subcutaneous (s.c.), daily), treated with Dantrolene (TD) (5 mg/kg body weight in saline, subcutaneous (s.c.), daily), and double-treated treated (TFD) with Formoterol (0,3 mg/kg body weight, subcutaneous (s.c.), daily) and Dantrolene (5 mg/kg body weight, subcutaneous (s.c.), daily). 7 days after tumour transplantation, muscle weight, grip force, and total physical activity were specified in all experimental groups. RESULTS: While formoterol had, as in previous studies, a very positive effect in reducing muscle weight loss, dantrolene had no effects, neither on skeletal muscle nor on any of the parameters studied. Finally, the combined treatment (formoterol and dantrolene) did not result in any significant benefit on the action of the ß2-agonist. CONCLUSION: It is concluded that, in the preclinical cachectic model used, no synergy exists between ß2-agonist treatment and the blockade of sarcoplasmic-calcium flow.

Do red cell transfusions increase the risk of necrotizing enterocolitis in premature infants?

OBJECTIVE: To test the hypothesis that red blood cell (RBC) transfusions increase the risk of necrotizing enterocolitis (NEC) in premature infants, we investigated whether the risk of "transfusion-associated" NEC is higher in infants with lower hematocrits and advanced postnatal age. STUDY DESIGN: Retrospective comparison of NEC patients and control patients born at < 34 weeks gestation. RESULTS: The frequency of RBC transfusions was similar in NEC patients (47/93, 51%) and control patients (52/91, 58%). Late-onset NEC (> 4 weeks of age) was more frequently associated with a history of transfusion(s) than early-onset NEC (adjusted OR, 6.7; 95% CI, 1.5 to 31.2; P = .02). Compared with nontransfused patients, RBC-transfused patients were born at earlier gestational ages, had greater intensive care needs (including at the time of onset of NEC), and longer hospital stay. A history of RBC transfusions within 48-hours before NEC onset was noted in 38% of patients, most of whom were extremely low birth weight infants. CONCLUSIONS: In most patients, RBC transfusions were temporally unrelated to NEC and may be merely a marker of overall severity of illness. However, the relationship between RBC transfusions and NEC requires further evaluation in extremely low birth weight infants using a prospective cohort design.

Effects of storage duration and volume on the quality of leukoreduced apheresis-derived platelets: implications for pediatric transfusion medicine.

BACKGROUND: Platelet (PLT) storage adversely affects PLT structure and function in vitro and is associated with decreased PLT recovery and function in vivo. In pediatric transfusion medicine, it is not uncommon for small residual volumes to remain in parent units after aliquot preparation of leukoreduced apheresis-derived PLTs (LR-ADP). However, limited data exist regarding the impact of storage on residual small-volume LR-ADP. STUDY DESIGN AND METHODS: Standard metabolic testing was performed on residual volumes of LR-ADP after aliquot removal and PLT aggregometry using a dual agonist of ADP and collagen was performed on stored, small-volume aliquots (10-80mL) created from an in vitro model of PLT storage. RESULTS: Seventy-seven LR-ADP underwent metabolic (n=67) or metabolic and aggregation (n=10) studies. All products maintained a pH value of more than 6.89 throughout storage. Lactate and pCO(2) increased proportionally with longer storage time. Regardless of acceptable metabolism during storage, aggregation in 10- to 20-mL aliquots was impaired by Day 4 and aliquots less than 40 mL demonstrated the most dramatic decrease in aggregation from baseline. CONCLUSIONS: Despite maintenance of acceptable metabolic conditions, residual volumes of LR-ADP develop impaired aggregation in vitro that may adversely affect PLT survival and function in vivo. At volumes below 40mL, LR-ADP revealed reduced aggregation. As a result, it is recommended to monitor and record volumes of LR-ADP used for pediatric transfusion. Moreover, once LR-ADP attain a volume of 50mL or less on Day 4 or Day 5 of storage, consider discarding these products until their in vivo efficacy can be studied.

Procedure-specific preoperative red blood cell preparation and utilization management in pediatric surgical patients.

BACKGROUND: Data-driven practices in preoperative red blood cell (RBC) preparation for pediatric surgical procedures are not well established. Adaptation of established adult preparation guidance methods to pediatric populations may improve perioperative RBC utilization. STUDY DESIGN AND METHODS: A retrospective audit of preoperative RBC preparation volumes (Vp) and intraoperative RBC transfusion volumes (Vt) for pediatric surgical procedures was undertaken at a large children's hospital from January to June 2006. RBC preparation-to-transfusion volume (mL/kg) ratios (P:T) were calculated for all surgeries, subspecialties, and select procedures. P:T equals Vp divided by Vt. Resulting P:Ts were compared to a target P:T of 2:1. A model for maximum procedure-specific Vp (Vp-max) defined Vp-max as the RBC transfusion volume able to meet the needs of 80% of patients undergoing an individual surgical procedure. Vp-max values were applied to the study data set to predict the impact on P:Ts and Vp. RESULTS: RBCs were prepared for 332 surgical procedures and transfused during 113 procedures. P:T was 3.5:1 for total surgical procedures (subspecialty range, 2.7:1-46:0), exceeding the 2:1 target. Vp-max modeling for spinal fusion, craniotomy for neoplasia, craniotomy for seizure, and craniosynostectomy yielded P:T ratios of 1.5:1, 1.5:1, 1.7:1, and 1.0:1, respectively, predicting a 30% decrease in Vp for these four surgical procedures. CONCLUSIONS: P:Ts for pediatric surgical procedures at this institution indicate potentially excessive preoperative RBC preparations. Determination of data-driven procedure-specific Vp may increase the efficiency of preoperative RBC preparation practices.

HLA alloimmunization is associated with RBC antibodies in multiply transfused patients with sickle cell disease.

BACKGROUND: Alloimmunization to minor red blood cell (RBC) antigens occurs commonly in sickle cell disease (SCD). Patients with alloimmunization demonstrate increased risk for new alloantibody formation with subsequent transfusion. Alloimmunization to human leukocyte antigens (HLA) can occur with RBC transfusion and may result in graft rejection during stem cell or organ transplantation. The prevalence and risk factors for HLA alloimmunization in multiply transfused pediatric SCD patients are unknown. PROCEDURE: A cross-sectional study of HLA alloimmunization in SCD patients aged 3-21 years with a history of >or=3 RBC transfusions was performed to test the hypothesis that HLA alloimmunization is associated with RBC alloimmunization. Antibodies to class I and class II HLA were measured by Flow Panel Reactive Antibody (FlowPRA). RESULTS: Seventy-three SCD patients (30 with RBC antibodies) were tested. HLA antibodies were detected in 25/73 (34%) patients; class I HLA antibodies occurred in 24/73 (33%) and class II HLA antibodies occurred in 3 (4%). Among patients with RBC antibodies, 16/30 (53%) had HLA antibodies, while 9/43 (21%) patients without RBC antibodies had HLA antibodies (OR 4.32 [1.6-12.1]). In a multivariate analysis, antibodies to RBC antigens were an independent predictor of HLA alloimmunization (P = 0.041). The association of RBC and HLA immunization was strongest among patients with no history of chronic transfusion therapy. CONCLUSIONS: This analysis is the first description of HLA alloimmunization in pediatric SCD patients who receive primarily leukoreduced RBC transfusions and demonstrates that HLA alloimmunization tendency is associated with antibodies to RBC antigens.

ABO-mismatched platelet transfusions: strategies to mitigate patient exposure to naturally occurring hemolytic antibodies.

Clinically significant hemolysis is a rare but potentially severe complication of administering an ABO-mismatched platelet transfusion. Platelet products from Group O donors, particularly single donor platelets (SDP) are most commonly implicated in these reactions. This is due to the presence of unusually high titers of anti-A which can be found in the plasma of some Group O donors and the large plasma volume of SDPs. These products can cause significant hemolysis when infused into a Group A or AB recipient. Random donor platelets from Group O donors have also been implicated. In practice, platelets are frequently transfused across ABO barriers though, ideally, in order to prevent or mitigate these reactions, platelet transfusions that are matched for ABO should be administered. However, limited availability of donor platelets as well as an abundance of Group O donors makes this a difficult standard to adhere to since often out-of group products are the only ones available. Methods to improve the safety of Group O products have focused on defining a safe level of isohemagglutinins so that the risk of hemolysis is alleviated when mismatched products are transfused. Determining the critical titer which defines a level above which a mismatched product should not be administered has been challenging. Non-standardized methods of isohemagglutinin titering and varying reports in the literature where products with a wide range of titers have been implicated in acute hemolytic transfusion reactions have made it difficult to determine a cut-off for labeling a product as high titer and thereby restricting its use to O recipients. Standards in the US place the responsibility for designing and implementing policies for the use of mismatched platelet products on each individual hospital transfusion service. Compliance requires only that there be an existing written policy which addresses the transfusion of products containing incompatible ABO antibodies but no specific procedures are required. In sharp contrast, European strategies have defined the low-end titer for which an out-of-group transfusion should not be given to an ABO-incompatible recipient. This testing is performed centrally at the Blood Centers who then make the determination on the status of a "dangerous donor". The progress in this European strategy may serve the US to stimulate a re-examination of its practices and policies for the advancement of platelet transfusion safety.

Femtosecond Double-Pulse Laser Ablation and Deposition of Co-Doped ZnS Thin Films.

Nanostructured thin films of Co-doped zinc sulfide were synthesized through femtosecond pulsed laser deposition. The scheme involved ablation of physically mixed Co and ZnS with pairs of ultrashort pulses separated in time in the 0-300 ps range. In situ monitorization of the deposition process was carried out through a simultaneous reflectivity measurement. The crystallinity of generated nanoparticles and the inclusion of Co in the ZnS lattice is demonstrated by transmission electron microscopy and energy dispersive X-ray microanalysis (TEM-EDX) characterization. Surface morphology, Raman response, and photoluminescence of the films have also been assessed. The role of interpulse temporal separation is most visible in the thickness of the films obtained at the same total fluence, with much thicker films deposited with short delays than with individual uncoupled pulses. The proportion of Co in the synthesized doped ZnS nanoparticles is found to be substantially lower than the original proportion, and practically independent on interpulse delay.