Thermal Stability and Mechanical Behavior of Ultrafine-Grained Titanium with Different Impurity Content.

Ultrafine-grained (UFG) commercially pure (Ti Grade 2) and high-purity (Ti 99.99%) titanium can be a good alternative to less biocompatible Ti alloys in many biomedical applications. Their severe plastic deformation may lead to a substantial increase of strength, but their highly refined microstructure show a lower thermal stability which may limit their range of applications. The purpose of this study was to investigate the effect of interstitial elements on the thermal stability of UFG Ti Grade 2 and high-purity Ti 99.99% processed by a multi-pass cold rolling to the total thickness reduction of 90%. The severely cold rolled Ti sheets were annealed at temperature in the range of 100-600 °C for 1 h and, subsequently, they were evaluated in terms of microstructure stability, mechanical performance as well as heat effects measured by differential scanning calorimetry (DSC). It was found that the microstructure and mechanical properties were relatively stable up to 200 and 400 °C in the case of UFG Ti 99.99% and Ti Grade 2, respectively. DSC measurements confirmed the aforementioned results about lower temperature of recovery and recrystallization processes in the high-purity titanium. Surprisingly, the discontinuous yielding phenomenon occurred in both investigated materials after annealing above their thermal stability range, which was further discussed based on their microstructural characteristics. Additionally, the so-called hardening by annealing effect was observed within their thermal stability range (i.e., at 100-400 °C for UFG Ti Grade 2 and 100 °C for UFG Ti 99.99%).

Giant plurihormonal pituitary adenoma in a child - case study.

OBJECTIVES: To describe the case of a 12-year-old girl with a rare plurihormonal pituitary macroadenoma secreting prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH), and alpha subunit (α-SU). CASE PRESENTATION: The patient experienced recurrent headaches and progressing loss of vision in one eye. During the examination, abnormalities such as tall stature, coarse facial features, enlarged feet and hands, tachycardia, hand tremor, hyperhidrosis, galactorrhea, and goiter were observed. Head magnetic resonance imaging (MRI) revealed a solid tumor in the anterior and middle cranial fossa, measuring 80 × 50 × 55 mm. A stereotactic biopsy revealed plurihormonal Pit-1 positive pituitary adenoma secreting PRL, GH, and TSH. A pituitary hyperfunction with PRL, GH, TSH, and α-SU excess was diagnosed. The patient was successfully treated pharmacologically with dopamine agonists and somatostatin analogue, and a decrease of tumor volume (30%) was achieved. CONCLUSIONS: When neurosurgery is not possible, long-term pharmacological treatment of plurihormonal pituitary macroadenoma can be a safe and relatively effective alternative.

Therapeutic effect of presurgical treatment with longacting octreotide (Sandostatin® LAR®) in patients with acromegaly.

INTRODUCTION: The aim of this study was to assess the therapeutic effect and the safety of pre-surgical treatment with long-acting octreotide in patients with acromegaly. MATERIAL AND METHODS: This project was conducted in 25 centres across Poland as a non-interventional, multicentre, observational study in patients with acromegaly, in which long-acting octreotide Sandostatin® LAR®) was administered before surgery. They were 148 patients included into the study: 88 females and 60 males aged 18-86 years (51.3 ± 13.4). RESULTS: Eighty patients completed the study (underwent tumour surgery). The CRF included: baseline visit, four follow-up visits every three months before surgery, and two follow-up visits every three months after surgery. Sandostatin® LAR® was administered every four weeks. The efficacy measures were as follows: change of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels, number of patients fulfilling criteria of cure, and change of adenoma (micro- and macroadenomas) size during the treatment. Normalisation of GH and IGF-1 concentrations were obtained in 42.4 and 49.1% of patients at the end of medical therapy, respectively. Normalisation of GH and IGF-1 concentrations were obtained in 77.9 and 83.8% of patients after surgery, respectively. Reduction of microadenoma size was documented in 58.8% of patients, and in 70% of patients with macroadenomas at the end of medical therapy. In 74.0% of patients no pituitary tumour was shown on MRI after surgery. CONCLUSION: We have shown good surgical outcome in patients with acromegaly after pre-treatment with somatostatin analogue, and good tolerance and safety of the therapy, supporting the national recommendation for pre-surgical treatment with long-acting somatostatin analogues in acromegaly patients.

Heteroleptic Copper(I) Pseudorotaxanes Incorporating Macrocyclic Phenanthroline Ligands of Different Sizes.

A series of copper(I) pseudorotaxanes has been prepared from bis[2-(diphenylphosphino)phenyl] ether (POP) and macrocyclic phenanthroline ligands with different ring sizes (m30, m37, and m42). Variable-temperature studies carried out on the resulting [Cu(mXX)(POP)]+ (mXX = m30, m37, and m42) derivatives have revealed a dynamic conformational equilibrium due to the folding of the macrocyclic ligand. The absorption and luminescence properties of the pseudorotaxanes have been investigated in CH2Cl2. They exhibit metal-to-ligand charge-transfer emission with photoluminescence quantum yields (PLQYs) in the range 20-30%. The smallest system [Cu(m30)(POP)]+ shows minimal differences in spectral shape and position compared to its analogues, suggesting a slightly distorted coordination environment. PLQY is substantially enhanced in poly(methyl methacrylate) films (∼40-45%). The study of emission spectra and excited-state lifetimes in powder samples as a function of temperature (78-338 K) reveals thermally activated delayed fluorescence, with sizable differences in the singlet-triplet energy gap compared to the reference compound [Cu(dmp)(POP)]+ (dmp = 2,9-dimethyl-1,10-phenanthroline) and within the pseudorotaxane series. The system with the largest ring ([Cu(m42)(POP)]+) has been tested as emissive material in OLEDs and affords bright green devices with higher luminance and greater stability compared to [Cu(dmp)(POP)]+, which lacks the macrocyclic ring. This highlights the importance of structural factors in the stability of electroluminescent devices based on Cu(I) materials.

Familial isolated pituitary adenomas (FIPA). Case report of four families and review of literature.

Background The majority of pituitary adenomas are sporadic, but about 5% of them occur in a familial setting, predominantly in multiple endocrine neoplasia type 1 and Carney complex. Familial isolated pituitary adenomas (FIPA), unrelated to the syndromes mentioned above, were also described. The clinical course of FIPA differs significantly from sporadic cases, and is characterized by a larger tumor size, more aggressive course and younger patients' age at the moment of recognition. Objectives The aim of this retrospective study is to present 4 families in which two closely related people were diagnosed with pituitary adenomas. Probably these cases are clinical manifestations of FIPA. Material and methods Eight patients within four families, presenting with anterior pituitary tumors were described. The authors analyzed medical and family histories of the patients, their imaging pictures (pituitary MRI/CT) and hormonal tests. Results Family 1.: two sisters with acromegaly in the course of macroadenoma. Family 2.: two brothers with clinically nonsecreting macroadenomas. Family 3.: father and daughter with clinically nonsecreting macroadenomas. Family 4.: young man with acromegaly caused by macroadenoma and a daughter of his mother`s sister with microprolactinoma. CONCLUSIONS: Familial isolated pituitary adenomas are more common than it was previously thought, therefore, specific questioning regarding family history should be a part of the workup of all patients with pituitary adenomas. Genetically induced pituitary tumors often have aggressive behavior in terms of tumor expansion and resistance to different treatment options and often involve a multidisciplinary approach that combines endocrine, neurosurgical, and radiological specialists.

Visible and Near-Infrared Emission from Lanthanoid ß-Triketonate Assemblies Incorporating Cesium Cations.

The reaction of the ß-triketonate ligands tris(4-methylbenzoyl)methanide and tribenzoylmethanide with the trivalent lanthanoids Eu3+, Er3+, and Yb3+ in the presence of Cs+ afforded polymeric structures where the repeating units are represented by bimetallic tetranuclear assemblies of formulation {[Ln(Cs)(ß-triketonate)4]2}n. The only exception is the structure formed by the reaction of tris(4-methylbenzoyl)methanide, Yb3+, and Cs+, which yielded a polymeric assembly where the repeating units are mononuclear Yb3+ complexes bridged by Cs+ cations. Photophysical measurements on the obtained materials confirmed efficient sensitization from the ligand excited states to the 4f* excited states of the three lanthanoids. According to transient absorption data, Er3+ and Yb3+ are sensitized via energy transfer from the triplet state of the ß-triketonate ligands. On the other hand, energy transfer to Eu3+ seems to occur via an alternative pathway, possibly directly via the singlet state or through ligand to metal charge transfer states. The emission measurements confirm efficient sensitization for all three lanthanoids and bright near-infrared emission for Er3+ and Yb3+, a characteristic that seems to be linked to the specific chemical structure of the ß-triketonate ligands.

Long-term complete remission of Crooke's corticotropinoma after temozolomide treatment.

INTRODUCTION: Crooke's corticotropinomas are the unique cause of Cushing's disease. The majority of them are aggressive macroadenomas, refractory to conventional therapy, with a high recurrence rate. The aim of the study was the presentation, in relation to data from the literature, of a case of a patient with ACTH-dependent Cushing's syndrome caused by recurrent Crooke's cells corticotropinoma, who achieved 33-month complete remission after treatment with temozolomide (TMZ). CASE REPORT: A 54-year-old man was diagnosed with Cushing's disease five years earlier on the basis of a typical clinical picture and hormonal tests. MRI revealed 32 × 29 × 24 mm macroadenoma. The patient underwent three subtotal selective transsphenoidal adenomectomies without retirement of hypercortisolaemia. A postoperative pathologic exploration revealed a densely granulated corticotroph Crooke's cells adenoma with MIB-1 index < 1%. Because of the large size of the tumour with its expansion to both cavernous sinuses and suprasellar region together with a compression of the optic chiasm, the patient was disqualified for gamma-knife. Due to an exhaustion of all conventional therapeutic options the patient was qualified to TMZ therapy. The standard dose of TMZ (150 g/m²) for five days every 28 days was implemented. After three courses of TMZ pronounced regression of tumour size with a marked hormonal and clinical improvement was certified. After six courses, consecutive tumour regression was observed. Nine courses resulted in a total radiological tumour shrinkage and hormonal normalisation. Despite the cassation of TMZ treatment the complete remission of the disease maintained for 33 months. CONCLUSION: Temozolomide can be an effective treatment option in invasive Crooke's cell corticotropinoma. (Endokrynol Pol 2016; 67 (5): 526-533).

Lanthanoid/Alkali Metal ß-Triketonate Assemblies: A Robust Platform for Efficient NIR Emitters.

The reaction of hydrated lanthanoid chlorides with tribenzoylmethane and an alkali metal hydroxide consistently resulted in the crystallization of neutral tetranuclear assemblies with the general formula [Ln(Ae⋅HOEt)(L)4 ]2 (Ln=Eu(3+) , Er(3+) , Yb(3+) ; Ae=Na(+) , K(+) , Rb(+) ). Analysis of the crystal structures of these species revealed a coordination geometry that varied from a slightly distorted square antiprism to a slightly distorted triangular dodecahedron, with the specific geometrical shape being dependent on the degree of lattice solvation and identity of the alkali metal. The near-infrared (NIR)-emitting assemblies of Yb(3+) and Er(3+) showed remarkably efficient emission, characterized by significantly longer excited-state lifetimes (τobs ≈37-47 µs for Yb(3+) and τobs ≈4-6 µs for Er(3+) ) when compared with the broader family of lanthanoid ß-diketonate species, even in the case of perfluorination of the ligands. The Eu(3+) assemblies show bright red emission and a luminescence performance (τobs ≈0.5 ms, ${{\Phi}{{{\rm L}\hfill \atop {\rm Ln}\hfill}}}$≈35-37 %, ηsens ≈68-70 %) more akin to the ß-diketonate species. The results highlight that the ß-triketonate ligand offers a tunable and facile system for the preparation of efficient NIR emitters without the need for more complicated perfluorination or deuteration synthetic strategies.

Temozolomide-Induced Shrinkage of Invasive Pituitary Adenoma in Patient with Nelson's Syndrome: A Case Report and Review of the Literature.

Introduction. Invasive tumours in Nelson's syndrome need aggressive therapy. Recent reports have documented the efficacy of temozolomide (TMZ) in the treatment of adenomas resistant to conventional management. Objective. The review of the literature concerning TMZ treatment of atypical corticotroph adenomas and a case study of 56-year-old woman who developed Nelson's syndrome. Treatment Proceeding. The patient with Cushing's disease underwent transsphenoidal adenomectomy followed by a 27-month-long period of remission. Due to a regrowth of the tumor, she underwent two reoperations followed by stereotactic radiotherapy. Because of treatment failures, bilateral adrenalectomy was performed. Then she developed Nelson's syndrome. A fourth transsphenoidal adenomectomy was performed, but there was a rapid recurrence. Five months later, she underwent a right frontotemporal craniotomy. Due to a rapid regrowth of the tumour, the patient did not receive gamma-knife therapy and was treated with cabergoline and somatostatin analogue for some time. Only TMZ therapy resulted in marked clinical, biochemical, and radiological improvement. To date, this is the first case of invasive corticotroph adenoma in Nelson's syndrome treated with temozolomide in Poland. Conclusion. In our opinion, temozolomide can be an effective treatment option of invasive adenomas in Nelson's syndrome.

Methylated Re(I) tetrazolato complexes: photophysical properties and Light Emitting Devices.

The irreversible reaction of methyl triflate with neutral Re(I) tetrazolato complexes of the type fac-[Re(diim)(CO)3(L)], where diim is either 1,10-phenanthroline or 2,2'-bipyridine and L is a para substituted 5-aryltetrazolate, yielded the corresponding cationic methylated complexes. While methylation occurred regioselectively at the N4 position of the tetrazole ring, the cationic complexes were found to exist in solution as equilibrating mixtures of linkage isomers, where the Re(i) centre was bound to either the N1 or N2 atom of the tetrazole ring. The existence of these isomers was highlighted both by NMR and X-ray crystallography studies. On the other hand, the two isomers appeared indistinguishable by IR, UV-Vis and luminescence spectroscopy. The prepared cationic complexes are all brightly phosphorescent in fluid and rigid solutions, with emission originating from triplet metal-to-ligand charge transfer excited states. Compared to their neutral precursors, which emit from admixtures of triplet metal-to-ligand and ligand-to-ligand charge transfer states, the methylated complexes exhibit blue-shifted emission characterised by elongated excited state lifetimes and increased quantum yields. The nature of the excited states for both the neutral and the methylated complexes was probed by resonance Raman spectroscopy and with the aid of time-dependent density functional theory calculations. Lastly, both the neutral and the methylated species were used as emitting phosphors in the fabrication of Organic Light Emitting Diodes and Light Emitting Electrochemical Cells.

Versatile bisethynyl[60]fulleropyrrolidine scaffolds for mimicking artificial light-harvesting photoreaction centers.

Fullerene-based tetrads, triads, and dyads are presented in which [60]fulleropyrrolidine synthons are linked to an oligo(p-phenyleneethynylene) antenna at the nitrogen atom and to electron-donor phenothiazine (PTZ) and/or ferrocene (Fc) moieties at the α carbon of the pyrrolidine cycle through an acetylene spacer. Cyclic voltammetry and UV/ Vis absorption spectra evidence negligible ground-state electronic interactions among the subunits. By contrast, strong excited-state interactions are detected upon selective light irradiation of the antenna (UV) or of the fullerene scaffold (Vis). When only PTZ is present as electron donor, photoinduced electron transfer to the fullerene unit is unambiguously detected in benzonitrile, but this is not the case when Fc is part of the multicomponent system. These results suggest that Fc is a formidable energy transfer quencher and caution should be used in choosing it as electron donor to promote efficient charge separation in multicomponent arrays.

Lanthanoid ß-triketonates: a new class of highly efficient NIR emitters for bright NIR-OLEDs.

The reaction of hydrated YbCl3 with potassium tribenzoylmethanide yields a new bimetallic tetranuclear Yb(3+)/K(+) assembly. This species not only possesses the longest excited state lifetime and quantum yield reported for the Yb(3+) diketonate family but is also suitable to be incorporated in NIR-OLEDs, whose performance outclasses any other reported lanthanoid-based device with NIR emission.

Type 2 diabetes mellitus in relation to place of residence: evaluation of selected aspects of socio-demographic status, course of diabetes and quality of life--a cross-sectional study.

INTRODUCTION AND OBJECTIVE: This study aims at answering what are the differences in socio-demographic status of patients with type 2 diabetes living in the city and the countryside and what is the impact of a place of residence on the level of metabolic control, the incidence of complications of diabetes and quality of life (QoL). MATERIALS AND METHODS: 274 patients were divided into 2 groups: residents of rural areas-28.2% (n=77) and residents of urban areas-71.9% (n=197). Self-reported questionnaires was used: EQ-5D, DQL-BCI and DSC-R. RESULTS: The group of residents of the countryside was characterized by a lower income and education level and a higher number of persons with disability pension. Patients living in the country had a higher body mass index in comparison to town inhabitants (32.6 kg/m(2) vs 30.9 kg/m(2), p=0.008) and shorter diabetes duration (8.4 versus 11.3 years, p=0.008). There were no differences between residents of the countryside and towns in terms of the method of treatment (oral antidiabetic drugs: 70.1% and 65.5%, p=0.3, Insulin: 29.9% and 36.5%, p=0.3, respectively), occurring chronic complications of diabetes (retinopathy: 14.3% and 14.2%, neuropathy: 6.5% and 7.6%, coronary heart disease: 44.45 and 37.1%, respectively) and the availability of diabetologists. Patients living in the countryside did not differ from town inhabitants in metabolic control and QoL assessment (EQ-5D index: 0.80 vs 0.79, p=0.9, EQ-VAS: 56.2 vs 54.3, p=0.2, DQL-BCI: 56.0 vs 53.9, p=0.1, DSC-R: 29.6 vs 29.4, p=0.7). CONCLUSIONS: The socio-demographic differences between groups dependent on the place of living did not exert a significant influence on the level of metabolic control of diabetes, the incidence of late complications or QoL assessment in the population studied.

Ultrasound stimulated nucleation and growth of a dye assembly into extended gel nanostructures.

A squaraine dye functionalized with a bulky trialkoxy phenyl moiety through a flexible diamide linkage (GA-SQ) capable of undergoing self-assembly has been synthesized and fully characterized. Rapid cooling of a hot solution of GA-SQ to 0 °C results in self-assembled precipitates consisting of two types of nanostructures, rings and ill-defined short fibers. The application of ultrasound modifies the conditions for the supersaturation-mediated nucleation, generating only one kind of nuclei and prompting the formation of crystalline fibrous structures, inducing gelation of solvent molecules. The unique self-assembling behavior of GA-SQ under ultrasound stimulus has been investigated in detail by using absorption, emission, FT-IR, XRD, SEM, AFM and TEM techniques. These studies reveal a nucleation growth mechanism of the self-assembled material, an aspect rarely scrutinized in the area of sonication-induced gelation. Furthermore, in order to probe the effects of nanoscale substrates on the sonication-induced self-assembly, a minuscule amount of single-walled carbon nanotubes was added, which leads to acceleration of the self-assembly through a heterogeneous nucleation process that ultimately affords a supramolecular gel with nanotape-like morphology. This study demonstrates that self-assembly of functional dyes can be judiciously manipulated by an external stimulus and can be further controlled by the addition of carbon nanotubes.

Azobenzene-based supramolecular polymers for processing MWCNTs.

Photothermally responsive supramolecular polymers containing azobenzene units have been synthesised and employed as dispersants for multi-walled carbon nanotubes (MWCNTs) in organic solvents. Upon triggering the trans-cis isomerisation of the supramolecular polymer intermolecular interactions between MWCNTs and the polymer are established, reversibly affecting the suspensions of the MWCNTs, either favouring it (by heating, i.e. cis→trans isomerisation) or inducing the CNTs' precipitation (upon irradiation, trans→cis isomerisation). Taking advantage of the chromophoric properties of the molecular subunits, the solubilisation/precipitation processes have been monitored by UV-Vis absorption spectroscopy. The structural properties of the resulting MWCNT-polymer hybrid materials have been thoroughly investigated via thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) and modelled with molecular dynamics simulations.

Luminescent blooming of dendronic carbon nanotubes through ion-pairing interactions with an Eu(III) complex.

A multiwalled carbon nanotube (MWCNT) scaffold was covalently functionalized with a second-generation polyamidoamine (PAMAM) dendron, presenting four terminal amino groups per grafted aryl moiety. These reactive functions were alkylated to obtain a positively charged polycationic dendron/carbon nanotube system (d-MWCNTs⋅Cl), which eventually underwent anion exchange reaction with a negatively charged and highly luminescent Eu(III) complex ([EuL(4)]⋅NEt(4), in which L = (2-naphtoyltrifluoroacetonate)). This process afforded the target material d-MWCNTs⋅[EuL(4)], in which MWCNTs are combined with red-emitting Eu(III) centers through electrostatic interactions with the dendronic branches. Characterization of the novel MWCNT materials was accomplished by means of TGA and TEM, whereas d-MWCNTs⋅Cl and d-MWCNTs⋅ [EuL(4)] further underwent XPS, SEM and Raman analyses. These studies demonstrate the integrity of the luminescent [EuL(4)](-) center in the luminescent hybrid, the massive load of the cationic binding sites, and the virtually complete anion-exchange into the final hybrid material. The occurrence of the ion-pairing interaction with MWCNTs was unambiguously demonstrated through DOSY NMR diffusion studies. Photophysical investigations show that MWCNTs⋅[EuL(4)] is a highly soluble and brightly luminescent red hybrid material in which MWCNTs act as photochemically inert scaffolds with negligible UV/Vis absorption, compared with the grafted Eu complex, and with no quenching activity. The high dispersibility of MWCNTs⋅[EuL(4)] in a polymer matrix makes it a promising luminophore for applications in material science.

Familial acromegaly - case study of two sisters with acromegaly.

In the majority of cases, acromegaly is sporadic. However, it can also occur in a familial setting as a component of MEN-1, MEN-4, Carney complex (CNC) or as the extremely rare syndrome of isolated familial somatotropinoma (IFS), the latter belonging to familial isolated pituitary adenomas (FIPA). The diagnosis of IFS is based on the recognition of acromegaly/gigantism in at least two family members, given that the family is not affected by MEN-1, MEN-4 or CNC. The authors present a case study of two sisters: a 56 year-old patient (case no. 1) and a 61 year-old patient (case no. 2). In both sisters, acromegaly was recognised in the course of pituitary macroadenoma. Neither of the sisters showed features of MEN-1, MEN-4 or Carney complex. The authors suppose that the presented cases are manifestations of IFS. However, this diagnosis has not been confirmed yet because of the poor availability of genetic tests.

Acromegaly in a patient with normal pituitary gland and somatotropic adenoma located in the sphenoid sinus.

Ectopic acromegaly is a very rare clinical entity occurring in less than 1% of acromegalic patients. In most cases it is caused by GHRH or rarely GH-secreting neoplasms. Even rarer are ectopic pituitary adenomas located in the sphenoid sinus or nasopharynx that originate from pituitary remnants in the craniopharyngeal duct. This dissertation presents the difficulties in visualizing GH-secreting adenoma located in the sphenoid sinus. A 55-year-old man had somatic features of acromegaly for several years. MRI imaging revealed a slightly asymmetric pituitary gland (14 yen 4 mm) without focal lesions. Simultaneously, a spherical mass, 10 mm in diameter, corresponding with ectopic microadenoma was demonstrated on the upper wall of the sphenoid sinus. The serum GH level was 4.3 mg/l, IGF-1 = 615 mg/l, and a lack of GH suppression with oral glucose was proven. After preliminary treatment with a long-acting somatostatin analogue, transsphenoidal pituitary tumour removal was performed. Histopathological, electron microscopical and immunohistochemical analysis revealed densely granulated somatotropic pituitary adenoma: GH(+), PRL(-), ACTH(-), TSH(-), FSH(-), LH(-), MIB1 < 1%, SSTR3(+) and SSTR5(+). Post-surgical evaluation showed normal pituitary MRI scans, GH and IGF-1 levels 0.18 mug/l and 140 mg/l, respectively, as well as normal GH suppression with oral glucose. The careful analysis of possible pituitary embryonic malformations points out their significance for proper localization of extrapituitary adenomas.

One- and two-photon induced fluorescence of Pacific Blue-labeled human serum albumin deposited on different core size silver colloids.

We studied one- and two-photon induced fluorescence of Pacific Blue (PB)-labeled human serum albumin (HSA) in the presence of different size silver colloids. The PB fluorescence emission intensity was observed with small (30-40 nm) and large (about 120 nm) colloids and compared with PB emission in absence of colloids. For the system with a small core size colloids we did not detect any fluorescence enhancement with one-photon excitation and the enhancement observed with two-photon excitation was about 2.5-fold. In contrast, for large silver colloids we observed about a 2-fold increase in PB fluorescence brightness for one-photon excitation, and the enhancement with two-photon excitation excided 13-folds. Much stronger increases in brightness observed with two-photon excitation, compared to one-photon excitation, indicate a dominant role of enhanced local field in fluorescence enhancement on silver colloids in solutions.

Waveguide-modulated surface plasmon-coupled emission of Nile blue in poly(vinyl alcohol) thin films.

Surface plasmon-coupled emission (SPCE) phenomenon is the coupling of excited fluorophores near a silver film with surface plasmons, resulting in directional emission into the underlying glass substrates. We report a complex coupling of Nile Blue fluorophore with 50 nm silver mirror, resulting in emission at several angles in the glass substrate, with either s or p polarization. This complex pattern of directional and polarized emission appears to be due to optical waveguide effects occurring when the sample thickness becomes comparable to the emission wavelength. We expect waveguide-modulated SPCE to have applications to biophysics and sensing.