Spectrally tunable chiral Bragg reflectors for on-demand beam generation.

We demonstrate the generation of spectrally tunable phase-dependent wavefronts, using the 2D Airy as the primary test case, via a polymer-stabilized cholesteric liquid crystal (PSCLC) element. Specifically, we use a novel spatial light modulator (SLM) based projection system to photo-align the initial helix angle landscape of the PSCLC so that it imparts the appropriate cubic phase profile to the reflected beam. This element is spectrally selective, with a reflection bandwidth of ≈ 100 nm, and electrically tunable from λ = 530 nm to 760 nm. Under both green and red laser illumination, the element is shown to conditionally form an Airy beam depending on the position of the electrically tailored reflection band. We briefly demonstrate the generality of this approach by producing PSCLC elements which form a computer-generated hologram and a higher-order Mathieu beam.

The digitally replicated denture technique: A case report.

OBJECTIVE: Conventional complete denture protocols require several patient appointments with multiple laboratory procedures. There are multiple workflows incorporating digital technology that can expedite the process, whereas increasing predictability. The proposed digitally replicated denture technique (DRDT) demonstrates a predictable workflow for fabricating complete dentures for patients with existing dentures. CLINICAL PROCEDURE: A patient's existing maxillary and mandibular complete dentures were scanned with an intraoral scanner. The generated STL was then printed using a desktop 3D printer. This served as a custom tray and record base to decrease patient chair time and associated laboratory procedures. CONCLUSION: The DRDT workflow incorporates digital technology into a complete denture protocol to minimize laboratory steps and chair time when fabricating complete dentures for patients with existing prostheses. CLINICAL SIGNIFICANCE: The use of a digitally replicated denture using rapid prototyping can streamline the process of complete denture fabrication for patients with existing dentures.

Curvature by design and on demand in liquid crystal elastomers.

The shape of liquid crystalline elastomers (LCEs) with spatial variation in the director orientation can be transformed by exposure to a stimulus. Here, informed by previously reported analytical treatments, we prepare complex spiral patterns imprinted into LCEs and quantify the resulting shape transformation. Quantification of the stimuli-induced shapes reveals good agreement between predicted and experimentally observed curvatures. We conclude this communication by reporting a design strategy to allow LCE films to be anchored at their external boundaries onto rigid substrates without incurring internal, mechanical-mismatch stresses upon actuation, a critical advance to the realization of shape transformation of LCEs in practical device applications.

Composite Zn1-x Cd x GeAs2 semiconductors: structural and electrical properties.

We present the studies of structural, transport and magnetotransport properties of [Formula: see text]Cd x GeAs2 crystals with the chemical content changing from 0 to 1. The structural studies indicate that this alloy exists as a composite two-phase material in almost the entire range of average chemical compositions. The two phase nature of our samples does have a significant influence on the carrier transport and magnetotransport of the composite alloy. The change of the conductivity type is observed at room temperature, from p-type for [Formula: see text] to n-type for x > 0.18, respectively. The Hall carrier mobility measured at room temperature decreases as a function of x from about 35 cm2 (V · s)-1 for the sample with x = 0 down to 3 cm2 (V · s)-1 for the sample with x = 0.233. For x > 0.233 the Hall carrier mobility shows an increase with x, up to the highest value around 875 cm2 (V · s)-1 observed for the sample with x = 1. Temperature dependent resistivity measurements indicate the presence of thermal activation of carriers with activation energy, E a, with values from 20 to 30 meV for all the studied samples. The temperature dependent Hall effect data show that the grain boundary limited transport is strong in all our samples. For the samples with [Formula: see text] the negative MR is observed at temperatures lower than 100 K and at low magnetic field values, [Formula: see text] T. This effect is interpreted as a weak localization phenomenon with low values of phase coherence length, [Formula: see text] nm.

Direct observation and temperature control of the surface Dirac gap in a topological crystalline insulator.

Since the advent of topological insulators hosting Dirac surface states, efforts have been made to gap these states in a controllable way. A new route to accomplish this was opened up by the discovery of topological crystalline insulators where the topological states are protected by crystal symmetries and thus prone to gap formation by structural changes of the lattice. Here we show a temperature-driven gap opening in Dirac surface states within the topological crystalline insulator phase in (Pb,Sn)Se. By using angle-resolved photoelectron spectroscopy, the gap formation and mass acquisition is studied as a function of composition and temperature. The resulting observations lead to the addition of a temperature- and composition-dependent boundary between massless and massive Dirac states in the topological phase diagram for (Pb,Sn)Se (001). Overall, our results experimentally establish the possibility to tune between massless and massive topological states on the surface of a topological system.

Topological crystalline insulator states in Pb(1-x)Sn(x)Se.

Topological insulators are a class of quantum materials in which time-reversal symmetry, relativistic effects and an inverted band structure result in the occurrence of electronic metallic states on the surfaces of insulating bulk crystals. These helical states exhibit a Dirac-like energy dispersion across the bulk bandgap, and they are topologically protected. Recent theoretical results have suggested the existence of topological crystalline insulators (TCIs), a class of topological insulators in which crystalline symmetry replaces the role of time-reversal symmetry in ensuring topological protection. In this study we show that the narrow-gap semiconductor Pb(1-x)Sn(x)Se is a TCI for x = 0.23. Temperature-dependent angle-resolved photoelectron spectroscopy demonstrates that the material undergoes a temperature-driven topological phase transition from a trivial insulator to a TCI. These experimental findings add a new class to the family of topological insulators, and we anticipate that they will lead to a considerable body of further research as well as detailed studies of topological phase transitions.

X-linked distal hereditary motor neuropathy maps to the DSMAX locus on chromosome Xq13.1-q21.

OBJECTIVE: To clinically characterize and map the gene locus in a three-generation family with an X-linked adult-onset distal hereditary motor neuropathy. METHODS: Microsatellite markers spanning the juvenile distal spinal muscular atrophy (DSMAX) locus were genotyped and analyzed using genetic linkage analysis. The promoter, untranslated and coding region of the gap junction beta1 (GJB1) gene was sequenced. Nine positional candidate genes were screened for disease mutations using high-resolution melt (HRM) analysis. RESULTS: The family showed significant linkage to markers on chromosome Xq13.1-q21. Haplotype construction revealed a disease-associated haplotype between the markers DXS991 and DX5990. Sequence analysis excluded pathogenic changes in the coding and promoter regions of the GJB1 gene. Additional fine mapping in the family refined the DSMAX locus to a 1.44-cM interval between DXS8046 and DXS8114. HRM analysis did not identify disease-associated mutations in the coding region of nine candidate genes. CONCLUSION: We have identified a family with adult-onset distal hereditary motor neuropathy that refines the locus reported for juvenile distal spinal muscular atrophy (DSMAX) on chromosome Xq13.1-q21. Exclusion of mutations in the coding and regulatory region of the GJB1 gene eliminated the CMTX1 locus as a cause of disease in this family. Nine positional candidate genes in the refined interval underwent mutation analysis and were eliminated as the pathogenic cause of DSMAX in this family. The syndrome in this family may be allelic to the juvenile distal spinal muscular atrophy first reported at this locus.

Relationships among ecology, demography and diseases of European bison (Bison bonasus).

The bison population in the Bialowieza Forest in Poland has now grown to approximately 300, while the herds in the Belarusian part of the forest total about 240 bison. The first signs of a health problem in these herds appeared in 1980, when two cases of balanoposthitis were detected in two bulls (2 and 5 years of age). Since 1980 research has been conducted to explain the cause of diseases, particularly balanoposthitis, and to monitor the health of bison in Bialowieza Forest. A total number of 614 bison (294 male and 320 female) of different ages was eliminated between 1980 and 2000. Not all the culled bison were examined (postmortem analysis, histopathological, bacteriological, virological and toxicological examinations, serological tests, molecular research). Based on the increase in numbers, reproduction in this population for the past 21 years is generally considered successful. Among 182 male bison eliminated during 1990-2000, only 85, or 47%, of the animals had balanoposthitis. Thus, the percentage of balanoposthitis cases went from 100% during the 1980s down to 47% in the past decade. It appears that the culling process has been a major factor leading to this decrease. It can be assumed that a set of factors is involved in the appearance of the disease (Corynebacterium spp., Bacillus sp., Pseudomonas aeruginosa, Escherichia coli, Ureoplasma spp, Fusobacterium necrophorum, Streptoccocus spp., Staphyloccocus spp.) while opportunistic infections including nematodes (Onchocerca spp.) are responsible for the occurrence of secondary lesions.

Simple method for the complete characterization of an optical pulse.

A novel and simple method to measure the amplitude and the phase of optical pulses is presented. The technique basically involves modulating the optical pulse train in a particular manner and then directly examining the resultant optical spectrum. This experimental measurement technique, which is extremely accurate and sensitive and can be implemented with an all-fiber setup, permits direct measurement of the phase of the optical signal in the frequency domain. Experimental results demonstrate the use of this measurement technique for characterizing optical pulses at 10 GHz from a gain-switched laser diode.

Stevens-Johnson syndrome associated with carvedilol therapy.

Stevens-Johnson syndrome, related to carvedilol use, has not been previously reported as a serious adverse experience requiring hospitalization. We report this reaction in a 71-year-old man with stable ischemic cardiomyopathy.

Maximum likelihood multivariate calibration.

Two new approaches to multivariate calibration are described that, for the first time, allow information on measurement uncertainties to be included in the calibration process in a statistically meaningful way. The new methods, referred to as maximum likelihood principal components regression (MLPCR) and maximum likelihood latent root regression (MLLRR), are based on principles of maximum likelihood parameter estimation. MLPCR and MLLRR are generalizations of principal components regression (PCR), which has been widely used in chemistry, and latent root regression (LRR), which has been virtually ignored in this field. Both of the new methods are based on decomposition of the calibration data matrix by maximum likelihood principal component analysis (MLPCA), which has been recently described (Wentzell, P. D.; et al. J. Chemom., in press). By using estimates of the measurement error variance, MLPCR and MLLRR are able to extract the optimum amount of information from each measurement and, thereby, exhibit superior performance over conventional multivariate calibration methods such as PCR and partial least-squares regression (PLS) when there is a nonuniform error structure. The new techniques reduce to PCR and LRR when assumptions of uniform noise are valid. Comparisons of MLPCR, MLLRR, PCR, and PLS are carried out using simulated and experimental data sets consisting of three-component mixtures. In all cases of nonuniform errors examined, the predictive ability of the maximum likelihood methods is superior to that of PCR and PLS, with PLS performing somewhat better than PCR. MLLRR generally performed better than MLPCR, but in most cases the improvement was marginal. The differences between PCR and MLPCR are elucidated by examining the multivariate sensitivity of the two methods.

Infrared emission spectroscopy of liquid samples with multivariate calibration as a model for process analytical applications.

Infrared emission spectroscopy and multivariate calibration are used to provide a method for the quantitative analysis of liquid samples. Differing forms of the data including second derivative and interferogram representation are used for prediction of sample composition, thickness and temperature. Comparisons are made with transmission measurements of the same samples. In some situations emission measurements may be the preferred method of analysis.

[Contamination of human milk with nitrates and nitrites]. / Skazenie mleka kobiecego azotanami i azotynami.

Human milk nitrates and nitrites were assayed colorimetrically. Colostrum samples were collected on the 3rd postpartum day from 59 women inhabiting Pulawy region and being potentially exposed to nitrogen compounds emitted from the industrial sources. Thirty five Lublin inhabitants serving as a control group were matched in age, parity and duration of pregnancy. Geometric mean value of nitrates and nitrites concentration in the human milk being 2.83 mg/L and 0.46 mg/L, respectively were higher in the examined group than those in the control group /2.76 mg/L and 0.32 mg/L/ but difference was statistically insignificant. Ratio of nitrates and nitrites in the examined samples was 7.38 on the average and the concentration of those compounds was related statistically significantly /p less than 0.001/. The average daily intake of nitrates and nitrites by the breast-fed neonates was 0.12 mg/kg body weight and 0.02 mg/kg body weight, respectively. These values did not exceed corresponding ADI recommended by the Joint Expert Committee of FAO/WHO in none case. Significantly positive correlation of examined mothers' age and parity with nitrates content in their colostrum was seen. In view of the obtained results is may be assumed that the examined colostrum samples contain low amounts of both nitrates and nitrites.

Tissue localization of the carcinogenic glutamic acid pyrolysis product Glu-P-1 in control and beta-naphthoflavone-treated mice and rats.

Autoradiograms obtained after i.v. injection of the 14C-labelled carcinogenic glutamic acid pyrolysis product Glu-P-1 to mice and rats showed a pronounced uptake of radioactivity in the liver, kidney, thyroid and nasal mucosa. High concentrations of radioactivity were present in the bile and intestinal contents at short post-injection times. In the male rat, the Zymbal's gland and the preputial gland were identified as sites of high and specific binding at all post-injection times examined. The liver and nasal mucosa were identified as sites of retention of non-extractable radioactivity. In the pigmented mouse, Glu-P-1 and/or its metabolites were accumulated in melanin. Glu-P-1 is known to be activated by cytochrome P-448. Pretreatment with beta-naphthoflavone (a cytochrome P-448 inducer) did not change the tissue localization of radioactivity in either species except for the liver where the overall labelling was decreased. Neither did pretreatment of mice with the glutathione-depleting agent phorone change the distribution pattern significantly. However, combined pretreatments of mice with either phorone or beta-naphthoflavone and the cytochrome P-448 inhibitor 9-hydroxyellipticine resulted in an increased overall retention of radioactivity in the body.

Epithelial binding of 1,2-dichloroethane in mice.

The metabolism and binding of 14C-labelled 1,2-dichloroethane (DCE) in female C57BL-mice were studied. As shown by whole-body autoradiography with heated and organic solvent-extracted tissue sections of i.v. injected mice, a selective localization of non-volatile and bound DCE-metabolites occurred in the nasal olfactory mucosa and the tracheo-bronchial epithelium. Low levels of metabolites were also present in the epithelia of the upper alimentary tract, vagina and eyelid, and in the liver and kidney. A decreased mucosal and epithelial binding was observed after pretreatment with metyrapone, indicating that the binding might be due to an oxidative metabolism of DCE. The quantitated levels of in vivo binding were considerably lower in mice injected i.p. with DCE, as compared to mice given equimolar doses of 14C-labelled 1,2-dibromoethane. In vitro experiments with 1000 g supernatants from various tissues showed that the nasal mucosa has a marked ability to activate DCE into products that become irreversibly bound to the tissue. It is proposed that the nasal olfactory mucosa is a target tissue for toxicity of DCE.

Cytologic characteristics of neoplastic and of regenerating hepatocytes in fine needle aspirates of rat liver.

L-azaserine (l-aza)-induced hepatocellular carcinoma (HCA) and hyperplastic liver lesions were studied in livers from 86 l-aza treated animals and 16 saline controls. Eight additional rats studied 24 or 48 hr after partial hepatectomy and 8 young rats studied after no experimental manipulation served as additional controls for determination of cytologic effects of increased cell turnover. Fine needle aspirates (FNA) were made of all gross liver lesions and of grossly normal liver; H&E stained sections of liver surrounding each needle track were made. The FNA were fixed in 95% ethanol, stained with a routine Papanicolaou stain, randomized, and evaluated using 18 cytologic features. They were diagnosed without knowledge of the histologic diagnosis or treatment group. Features were analyzed with discriminant function analysis to determine their relative importance in making the diagnosis. FNA proved to be an accurate method for diagnosis of hepatocellular lesions in laboratory animals. The cytologic features of greatest usefulness in establishing the diagnosis were cord pattern, chromatin pattern, nucleolar size and nuclear membrane irregularity. FNA could provide a useful experimental technique for following evolving lesions serially and for identifying subgroups within hyperplastic nodules.

Tissue binding of 1,2-dibromoethane in the cynomolgus monkey (Macaca fascicularis).

Autoradiography at different levels of resolution was used to study the tissue-binding of 1,2-dibromo[14C]ethane (DBE) in the cynomolgus monkey (Macaca fascicularis) in vivo (i.p. injection) and in vitro. The results show that DBE is metabolized to products which become bound to the tissues, preferentially in the liver and the kidney tubules. A distinct binding of radioactivity was also found in the adrenal zona reticularis. The binding of radioactivity in the surface epithelia of the respiratory and upper alimentary tract was not as high and striking as that previously observed in rodents. The results show that the sites of tissue-binding of DBE in the cynomolgus monkey correspond to the sites of tissue lesion observed in humans poisoned with DBE.