Positioning Vascularized Composite Allotransplantation in the Spectrum of Transplantation

DTIC Science & Technology

2016-10-01

did not reject the third-party cardiac allografts , but instead rejected the original VCA tissues (Fig. 2, left panel). To test whether RPM impaired...long-term VCA survival, but the rejection of VCA tissues as a result of third party cardiac allografting suggests the incomplete regulation of host...mechanisms contributing to rejection of vascularized composite allografts (VCA) in murine models, and how these may be overcome to promote long-term

Simultaneous bone marrow and composite tissue transplantation in rats treated with nonmyeloablative conditioning promotes tolerance1

PubMed Central

Xu, Hong; Ramsey, Deborah M.; Wu, Shengli; Bozulic, Larry D.; Ildstad, Suzanne T.

2012-01-01

Background Approaches to safely induce tolerance in vascularized composite allotransplantation (VCA) with chimerism through bone marrow transplantation (BMT) are currently being pursued. However, the VCA were historically performed sequentially after donor chimerism was established. Delayed VCA is not clinically applicable due to the time constraints associated with procurement from deceased donors. A more clinically relevant approach to perform both the BMT and VCA simultaneously was evaluated. Methods WF (RT1Au) rats were treated with a short course of immunosuppressive therapy (anti-αβ-TCR mAb, FK-506, and anti-lymphocyte serum). One day prior to BMT, rats were treated with varying doses of total body irradiation (TBI) followed by transplantation of heterotopic osteomyocutaneous flaps from hind limbs of ACI (RT1Aabl) rats. Results 80% of rats conditioned with 300 cGy TBI and 40% of rats receiving 400 cGy TBI accepted the VCA. Mixed chimerism was detected in peripheral blood at one month post-VCA, but chimerism was lost in all transplant recipients by 4 months. The majority of peripheral donor cells originated from the BMT and not the VCA. Acceptors of VCA were tolerant of a donor skin graft challenge and no anti-donor antibodies were detectable, suggesting a central deletional mechanism for tolerance. Regulatory T cells (Treg) from spleens of acceptors more potently suppressed lymphocyte proliferation than Treg from rejectors in the presence of donor stimulator cells. Conclusions These studies suggest that simultaneous BMT and VCA may establish indefinite allograft survival in rats through Treg-mediated suppression and thymic deletion of alloreactive T cells. PMID:23250336

Effect of doping on electronic properties of HgSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nag, Abhinav, E-mail: abhinavn76@gmail.com; Sastri, O. S. K. S., E-mail: sastri.osks@gmail.com; Kumar, Jagdish, E-mail: jagdishphysicist@gmail.com

2016-05-23

First principle study of electronic properties of pure and doped HgSe have been performed using all electron Full Potential Linearized Augmented Plane Wave (FP-LAPW) method using ELK code. The electronic exchange and co-relations are considered using Generalized Gradient Approach (GGA). Lattice parameter, Density of States (DOS) and Band structure calculations have been performed. The total energy curve (Energy vs Lattice parameter), DOS and band structure calculations are in good agreement with the experimental values and those obtained using other DFT codes. The doped material is studied within the Virtual Crystal Approximation (VCA) with doping levels of 10% to 25% ofmore » electrons (hole) per unit cell. Results predict zero band gap in undopedHgSe and bands meet at Fermi level near the symmetry point Γ. For doped HgSe, we found that by electron (hole) doping, the point where conduction and valence bands meet can be shifted below (above) the fermi level.« less

Donor and procurement related issues in vascularized composite allograft transplantation.

PubMed

McDiarmid, Sue V

2013-12-01

To understand the unique requirements of vascularized composite allograft (VCA) donation and procurement practices and the integral role of the established nationwide organ procurement organizations in organ procurement. The recent issuance of a Final Rule (July 2013) by the United States Secretary of Health that redefines VCAs as organs rather than tissues, opens up the potential to formalize policies and procedures, under the auspices of the Organ Procurement and Transplantation Network, that can improve VCA donation, procurement practices, develop allocation algorithms and provide transparent oversight. Improved VCA donation rates, procurement procedures and broader sharing nationwide of VCA donors will have important implications in advancing the emerging field of VCA transplantation.

Serological diagnosis of Epstein-Barr virus infection: Problems and solutions

PubMed Central

De Paschale, Massimo; Clerici, Pierangelo

2012-01-01

Serological tests for antibodies specific for Epstein-Barr virus (EBV) antigens are frequently used to define infection status and for the differential diagnosis of other pathogens responsible for mononucleosis syndrome. Using only three parameters [viral capsid antigen (VCA) IgG, VCA IgM and EBV nuclear antigen (EBNA)-1 IgG],it is normally possible to distinguish acute from past infection: the presence of VCA IgM and VCA IgG without EBNA-1 IgG indicates acute infection, whereas the presence of VCA IgG and EBNA-1 IgG without VCA IgM is typical of past infection. However, serological findings may sometimes be difficult to interpret as VCA IgG can be present without VCA IgM or EBNA-1 IgG in cases of acute or past infection, or all the three parameters may be detected simultaneously in the case of recent infection or during the course of reactivation. A profile of isolated EBNA-1 IgG may also create some doubts. In order to interpret these patterns correctly, it is necessary to determine IgG avidity, identify anti-EBV IgG and IgM antibodies by immunoblotting, and look for heterophile antibodies, anti-EA (D) antibodies or viral genome using molecular biology methods. These tests make it possible to define the status of the infection and solve any problems that may arise in routine laboratory practice. PMID:24175209

Long-Term Tolerance Towards Haploidentical Vascularized Composite Allograft Transplantation in a Canine Model Using Bone Marrow or Mobilized Stem Cells

PubMed Central

Chang, Jeff; Graves, Scott S.; Butts-Miwongtum, Tiffany; Sale, George E.; Storb, Rainer; Mathes, David W.

2017-01-01

Background The development of safe and reliable protocols for the transplantation of the face and hands may be accomplished with animal modeling of transplantation of vascularized composite allografts (VCA). Previously, we demonstrated that tolerance to a VCA could be achieved after canine recipients were simultaneously given marrow from a dog leukocyte antigen (DLA) identical donor. In the present study, we extend those findings across a DLA mismatched barrier. Methods Eight Recipient dogs received total body irradiation (4.5 cGy), hematopoietic cell transplantation (HCT), either marrow (n=4) or granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood stem cells (n=4), and a VCA transplant from the HCT donor. Post grafting immunosuppression consisted of mycophenolate mofetil (28 days) and cyclosporine (35 days). Results In 4 dogs receiving bone marrow, 1 accepted both its marrow transplant and demonstrated long-term tolerance to the donor VCA (>52 weeks). Three dogs rejected both their marrow transplants and VCA at 5–7 weeks posttransplant. Dogs receiving mobilized stem cells all accepted their stem cell transplant and became tolerant to the VCA. However, 3 dogs developed graft-versus-host disease (GVHD) while 1 dog rejected its stem cell graft by week 15 but exhibited long-term tolerance towards its VCA (>90 weeks). Conclusion The data suggest that simultaneous transplantation of mobilized stem cells and a VCA is feasible and leads to tolerance towards the VCA in a haploidentical setting. However, there is a higher rate of donor stem cell engraftment compared to marrow HCT and an increase in the incidence of GVHD. PMID:27861292

78 FR 40033 - Organ Procurement and Transplantation Network

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

... regarding OPTN policy development for VCAs. They noted that VCA transplantation remains an experimental... best use of organs; shall be specific for each organ type; shall be designed to avoid wasting organs... suggested that, as an experimental field and given the small number of VCA transplants at this time, VCA...

Plasma cortisol levels and reactivation of latent Epstein-Barr virus in response to examination stress.

PubMed

Glaser, R; Pearl, D K; Kiecolt-Glaser, J K; Malarkey, W B

1994-01-01

In this study, we explored the possibility that glucocorticoid hormones, known to increase under stress, might be one component of the mechanism involved in induction of latent Epstein Barr virus (EBV). We obtained blood samples from 45 male medical students during examinations and approximately 3-4 weeks before the examinations (baseline) and measured antibody titers to EBV and plasma cortisol levels. We found reproducible changes in EBV, virus capsid antigen (VCA) antibody titers, with higher antibody titers observed in the examination blood samples consistent with the reactivation of latent virus. However, we found no evidence that day and night plasma cortisol values across the sampling points changed significantly from baseline to examinations. Therefore, academic stress did not elevate cortisol levels, but increases in EBV VCA antibody titers were still observed. The data suggest in these subjects that other neuropeptides or hormones were involved in the induction of latent EBV.

Prognostic value of serum Epstein-Barr virus antibodies in patients with nasopharyngeal carcinoma and undetectable pretreatment Epstein-Barr virus DNA.

PubMed

Yao, Ji-Jin; Lin, Li; Jin, Ya-Nan; Wang, Si-Yang; Zhang, Wang-Jian; Zhang, Fan; Zhou, Guan-Qun; Cheng, Zhi-Bin; Qi, Zhen-Yu; Sun, Ying

2017-08-01

Epstein-Barr virus (EBV) is closely associated with nasopharyngeal carcinoma (NPC). Serum IgA antibodies against early antigen (EA-IgA) and viral capsid antigen (VCA-IgA) are the most commonly used to screen for NPC in endemic areas. However, the prognostic value of serum EA-IgA and VCA-IgA in patients with NPC is less clear. We hypothesize that serum EA-IgA and VCA-IgA levels have prognostic impact for survival outcomes in NPC patients with undetectable pretreatment EBV (pEBV) DNA. In this series, 334 patients with non-metastatic NPC and undetectable pEBV DNA were included. Serum EA-IgA and VCA-IgA were determined by ELISA. After analysis, serum EA-IgA and VCA-IgA loads correlated positively with T, N, and overall stage (all P < 0.05). Serum EA-IgA was not associated with survival outcome in univariable analyses. But patients with serum VCA-IgA >1:120 had significantly inferior 5-year progression-free survival (80.4% vs 89.6%, P = 0.025), distant metastasis-free survival (88.4% vs 94.8%, P = 0.050), and locoregional relapse-free survival (88.4% vs 95.6%, P = 0.023; log-rank test). Multivariable analyses revealed that N stage was the only independent prognostic factor (all P < 0.05), but the VCA-IgA became insignificant. Further analyses revealed that serum VCA-IgA was not an independent prognostic factor in early N (N0-1) or advanced N (N2-3) stage NPC. In summary, although both EA-IgA and VCA-IgA correlate strongly with TNM stage, our analyses do not suggest that these antibodies are prognostic biomarkers in patients with NPC and undetectable pEBV DNA. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Vitamin K2, a menaquinone present in dairy products targets castration-resistant prostate cancer cell-line by activating apoptosis signaling.

PubMed

Dasari, Subramanyam; Samy, Angela Lincy Prem Antony; Kajdacsy-Balla, Andre; Bosland, Maarten C; Munirathinam, Gnanasekar

2018-05-01

The aim of this study was to evaluate the therapeutic effects of vitamin K2 (VK2) on castration-resistant prostate cancer (CRPC) and its anti-cancer mechanisms in a pre-clinical study using a VCaP cell line (ATCC ® CRL-2876™) which was established from a vertebral bone metastasis from a patient with hormone refractory prostate cancer. Our data showed that VK2 significantly inhibited CRPC VCaP cell proliferation in a dose-dependent manner at 48 h treatment in vitro. In addition, VK2 reduced the migration potential of VCaP cells and inhibited anchorage-independent growth of these cells. Our results also showed that VK2 induces apoptosis in VCaP cells. Furthermore, VK2 enforced growth arrest in VCaP cells by activating cellular senescence. Notably, VK2 treatment elevated the levels of reactive oxygen species in VCaP cells. Western blot analysis revealed that VK2 downregulated the expression of androgen receptor, BiP, survivin, while activating caspase-3 and -7, PARP-1 cleavage, p21 and DNA damage response marker, phospho-H2AX in VCaP cells. In conclusion, our study suggests that VK2 might be a potential anti-cancer agent for CRPC by specifically targeting key anti-apoptotic, cell cycle progression and metastasis-promoting signaling molecules. Copyright © 2018 Elsevier Ltd. All rights reserved.

Quantitation of valve regurgitation severity by three-dimensional vena contracta area is superior to flow convergence method of quantitation on transesophageal echocardiography.

PubMed

Abudiab, Muaz M; Chao, Chieh-Ju; Liu, Shuang; Naqvi, Tasneem Z

2017-07-01

Quantitation of regurgitation severity using the proximal isovelocity acceleration (PISA) method to calculate effective regurgitant orifice (ERO) area has limitations. Measurement of three-dimensional (3D) vena contracta area (VCA) accurately grades mitral regurgitation (MR) severity on transthoracic echocardiography (TTE). We evaluated 3D VCA quantitation of regurgitant jet severity using 3D transesophageal echocardiography (TEE) in 110 native mitral, aortic, and tricuspid valves and six prosthetic valves in patients with at least mild valvular regurgitation. The ASE-recommended integrative method comprising semiquantitative and quantitative assessment of valvular regurgitation was used as a reference method, including ERO area by 2D PISA for assigning severity of regurgitation grade. Mean age was 62.2±14.4 years; 3D VCA quantitation was feasible in 91% regurgitant valves compared to 78% by the PISA method. When both methods were feasible and in the presence of a single regurgitant jet, 3D VCA and 2D PISA were similar in differentiating assigned severity (ANOVAP<.001). In valves with multiple jets, however, 3D VCA had a better correlation to assigned severity (ANOVAP<.0001). The agreement of 2D PISA and 3D VCA with the integrative method was 47% and 58% for moderate and 65% and 88% for severe regurgitation, respectively. Measurement of 3D VCA by TEE is superior to the 2D PISA method in determination of regurgitation severity in multiple native and prosthetic valves. © 2017, Wiley Periodicals, Inc.

Positioning Vascularized Composite Allotransplantation in the Spectrum of Transplantation

DTIC Science & Technology

2015-10-01

composite allograft (VCA) survival without a need for maintenance immunosuppression. 12th Congress of the International Hand and Composite Tissue ...14. ABSTRACT We have continued our studies of the immune mechanisms contributing to rejection of vascularized composite allografts (VCA) in murine...models, and how these may be overcome to promote long-term allograft survival. We have now firmly established an orthotopic hind limb VCA model in our

Preclinical Models in Vascularized Composite Allotransplantation

DTIC Science & Technology

2015-06-28

VCA) has the potential to reconstruct any non-visceral tissue defect, using like for like tissue, delivering optimal form and function. Over 150 VCA... Reconstructive transplantation Introduction To date, over 150 VCA transplants have been performed,most commonly of the hand and face, but also abdominal wall...larynx, lower limb, uterus and penis [1, 2]. Any non-visceral tissue defect can potentially be reconstructed in this manner using like for like tissue

The significance of serum IgM IgA and IgG antibodies specific for Epstein-Barr virus as determined by immunoperoxidase assay in the rapid diagnosis of infectious mononucleosis.

PubMed

Hadar, T; Margalith, M; Sagiv, E; Sarov, B; Sarov, I

1995-05-01

The feasibility of using serum IgM, IgA and IgG antibodies specific to Epstein-Barr virus (EBV) viral capsid antigen (VCA), as determined by immunoperoxidase assay (IPA), for the early diagnosis of mononucleosis was evaluated in 65 patients with infectious mononucleosis (IMN). Control groups consisted of 104 healthy students and 15 cytomegalovirus-infected patients. In the first serum sample obtained upon admission, IgM antibodies (titer > or = 64) to EBV VCA were found in 64 of the 65 IMN patients (98%), while EBV-VCA IgA antibodies (titer > or = 32) were found in 32 patients (49%). In those particular titers, no EBV-VCA IgM or IgA antibodies were found in any of the control sera. EBV-VCA-specific IgM antibodies were also not detected in any of the 15 patients with cytomegalovirus infection. In sera obtained from IMN patients within 10 days of the onset of symptoms, 18 of 19 (95%) were IgM seropositive. This study demonstrates that serum EBV-VCA IgM antibodies (titer > or = 64) as determined by IPA are highly specific (100%) and highly sensitive (98%) and can be of value for the early and rapid diagnosis of EBV-IMN infection.

Three-dimensional color Doppler echocardiographic quantification of tricuspid regurgitation orifice area: comparison with conventional two-dimensional measures.

PubMed

Chen, Tien-En; Kwon, Susan H; Enriquez-Sarano, Maurice; Wong, Benjamin F; Mankad, Sunil V

2013-10-01

Three-dimensional (3D) color Doppler echocardiography (CDE) provides directly measured vena contracta area (VCA). However, a large comprehensive 3D color Doppler echocardiographic study with sufficiently severe tricuspid regurgitation (TR) to verify its value in determining TR severity in comparison with conventional quantitative and semiquantitative two-dimensional (2D) parameters has not been previously conducted. The aim of this study was to examine the utility and feasibility of directly measured VCA by 3D transthoracic CDE, its correlation with 2D echocardiographic measurements of TR, and its ability to determine severe TR. Ninety-two patients with mild or greater TR prospectively underwent 2D and 3D transthoracic echocardiography. Two-dimensional evaluation of TR severity included the ratio of jet area to right atrial area, vena contracta width, and quantification of effective regurgitant orifice area using the flow convergence method. Full-volume breath-hold 3D color data sets of TR were obtained using a real-time 3D echocardiography system. VCA was directly measured by 3D-guided direct planimetry of the color jet. Subgroup analysis included the presence of a pacemaker, eccentricity of the TR jet, ellipticity of the orifice shape, underlying TR mechanism, and baseline rhythm. Three-dimensional VCA correlated well with effective regurgitant orifice area (r = 0.62, P < .0001), moderately with vena contracta width (r = 0.42, P < .0001), and weakly with jet area/right atrial area ratio. Subgroup analysis comparing 3D VCA with 2D effective regurgitant orifice area demonstrated excellent correlation for organic TR (r = 0.86, P < .0001), regular rhythm (r = 0.78, P < .0001), and circular orifice (r = 0.72, P < .0001) but poor correlation in atrial fibrillation rhythm (r = 0.23, P = .0033). Receiver operating characteristic curve analysis for 3D VCA demonstrated good accuracy for severe TR determination. Three-dimensional VCA measurement is feasible and obtainable in the majority of patients with mild or greater TR. Three-dimensional VCA measurement is also feasible in patients with atrial fibrillation but performed poorly even with <20% cycle length variation. Three-dimensional VCA has good cutoff accuracy in determining severe TR. This simple, straightforward 3D color Doppler measurement shows promise as an alternative for the quantification of TR. Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

High prevalence of immunoglobulin A antibody against Epstein-Barr virus capsid antigen in adult patients with lupus with disease flare: case control studies.

PubMed

Chen, Chung-Jen; Lin, Kuei-Hsiang; Lin, Shih-Chang; Tsai, Wen-Chan; Yen, Jeng-Hsien; Chang, Shun-Jen; Lu, Sheng-Nan; Liu, Hong-Wen

2005-01-01

Systemic lupus erythematosus (SLE) is a severe autoimmune disease with rare remission and recurrent flare. Epstein-Barr virus (EBV) infection has been reported to be strongly associated with SLE in the United States, but with an inconclusive role in Asia. We investigated the role of EBV infection in patients with SLE in Taiwan, with one of the highest population densities in Asia. We conducted case-control studies to test whether EBV infection was associated with adult SLE in Taiwan. In the first study, 36 adults with SLE and 36 sex and age matched controls were enrolled for examination of serum IgG, IgM, and IgA antibody against EBV-virus capsid antigen (EBV-VCA). In the second study, another 36 adult lupus cases and 36 matched controls were enrolled to confirm the high prevalence of IgA antibody against EBV-VCA found in the first study. Further, both groups of SLE patients were combined to analyze the association between the existence of IgA antibody against EBV-VCA and disease activity (determined by SLEDAI score) and disease flare in patients with SLE. In the first study, IgA antibody against EBV-VCA was the only marker with significantly higher prevalence in adults with SLE compared to healthy adults (36.1% vs 5.6%; p < 0.005). In the second study, we confirmed that the prevalence of IgA antibody against EBV-VCA was indeed higher in adults with SLE (38.9% vs 2.8%; p < 0.001). With further analysis (pooling analysis), adult SLE patients with IgA antibody against EBV-VCA had higher disease activity compared to SLE patients without IgA antibody against EBV-VCA (SLEDAI 7.8 +/- 6.6 vs 3.3 +/- 2.1; p < 0.001). SLE patients with flare showed much higher prevalence of IgA antibody against EBV-VCA compared to those without flare (81.3% vs 25.0%; p < 0.001). This is the first evidence that IgA antibody against EBV-VCA is strongly associated with disease flare in SLE patients. It suggests that EBV reactivation may contribute toward the disease flare of SLE.

Immunological and inflammatory mapping of vascularized composite allograft rejection processes in a rat model

PubMed Central

Friedman, Or; Carmel, Narin; Sela, Meirav; Abu Jabal, Ameen; Inbal, Amir; Ben Hamou, Moshe; Krelin, Yakov; Gur, Eyal

2017-01-01

Background Hand and face vascularized composite allotransplantation (VCA) is an evolving and challenging field with great opportunities. During VCA, massive surgical damage is inflicted on both donor and recipient tissues, which may contribute to the high VCA rejection rates. To segregate between the damage-induced and rejection phase of post-VCA responses, we compared responses occurring up to 5 days following syngeneic versus allogeneic vascularized groin flap transplantations, culminating in transplant acceptance or rejection, respectively. Methods The immune response elicited upon transplantation of a syngeneic versus allogeneic vascularized groin flap was compared at Post-operative days 2 or 5 by histology, immunohistochemistry and by broad-scope gene and protein analyses using quantitative real-time PCR and Multiplex respectively. Results Immune cell infiltration began at the donor-recipient interface and paralleled expression of a large group of wound healing-associated genes in both allografts and syngrafts. By day 5 post-transplantation, cell infiltration spread over the entire allograft but remained confined to the wound site in the syngraft. This shift correlated with upregulation of IL-18, INFg, CXCL9, 10 and 11, CCL2, CCL5, CX3CL1 and IL-10 in the allograft only, suggesting their role in the induction of the anti-alloantigen adaptive immune response. Conclusions High resemblance between the cues governing VCA and solid organ rejection was observed. Despite this high resemblance we describe also, for the first time, a damage induced inflammatory component in VCA rejection as immune cell infiltration into the graft initiated at the surgical damage site spreading to the entire allograft only at late stage rejection. We speculate that the highly inflammatory setting created by the unique surgical damage during VCA may enhance acute allograft rejection. PMID:28746417

Capillary Thrombosis in the Skin: A Pathologic Hallmark of Severe/Chronic Rejection of Human Vascularized Composite Tissue Allografts?

PubMed

Kanitakis, Jean; Petruzzo, Palmina; Gazarian, Aram; Karayannopoulou, Georgia; Buron, Fannie; Dubois, Valérie; Thaunat, Olivier; Badet, Lionel; Morelon, Emmanuel

2016-04-01

Vascularized composite tissue allografts (VCA) can undergo rejection, manifesting pathologically with skin changes that form the basis of the Banff 2007 classification of VCA rejection. We have followed 10 human VCA recipients (7 with hand allografts, 3 with face allografts) for pathological signs of rejection. All of them developed episodes of acute rejection. Two patients with hand allografts presented in some of their skin biopsies an as yet unreported pathological finding in human VCA, consisting of capillary thromboses (CT) in the upper dermis. Capillary thrombosis was associated with other typical changes of grade II to III VCA rejection, namely, perivascular T cell infiltrates, but not with vascular C4d deposits (in formalin-fixed tissue). Clinically, the lesions presented as red or violaceous (lichenoid) cutaneous maculopapules. The first patient had several episodes of acute rejection during the 7-year follow-up. The second patient developed donor-specific antibodies; some months after CT were first observed, he developed chronic rejection leading to partial amputation of the allograft. Pathological examination of the skin showed graft vasculopathy and occasional C4d deposits in cutaneous capillaries. Capillary thrombosis seems to be a novel pathologic finding associated with human VCA rejection. Although its mechanism (immunologic vs nonimmunologic) remains unclear, this finding could carry an unfavorable prognostic significance, prompting close monitoring of the patients for severe/chronic rejection.

Anti-Epstein-Barr virus antibodies in Beijing during 2013-2017: What we have found in the different patients.

PubMed

Cui, Jingtao; Yan, Wenjuan; Xu, Shaoxia; Wang, Qiaofeng; Zhang, Weihong; Liu, Wenjing; Ni, Anping

2018-01-01

Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC) which is prevalent in South China, and its association with systemic lupus erythematosus (SLE) or other autoimmune diseases has not been studied in the mainland of China. The EBV serological tests have been performed on patients with various diseases or manifestations for years at our institution and their values need to be evaluated. For routine medical purposes, anti-EB viral capsid antigen (VCA) IgG, IgA and IgM antibodies, anti-EBV diffuse early antigen (EA-D) IgA antibodies, and anti-EBV nuclear antigen-1(EBNA-1) IgG antibodies were tested with commercial enzyme-linked immunosorbent assay (ELISA) in patients visiting Peking Union Medical College Hospital between 2013 and 2017. The test results were analyzed in this retrospective study. There were a total of 11122 serum samples available to be tested in the study. As indicators of past EBV infection, the prevalence of VCA-IgG/EBNA1-IgG were 66.6%/58.5%, 84.3%/78.8%, 92.9%/87.0% and 98.5%/95.4% in patients aged under 5 years, 6-10 years, 11-20 years and 21-30 years old, respectively, and these values maintained at this highest rate as age increased further. The prevalence of VCA-IgM, as a parameter of acute EBV infection, was 14.6%, 10.2%, 10.4%, 6.3% and 3.1% in patients aged under 5 years, 6-10 years,11-20 years, 21-30 years, 31-40 years old, respectively, and decreased to 2%~3% in older patients. Patients with elevated serum liver enzymes were more likely to have a higher prevalence of EA/D IgA antibody (P < 0.01) and young patients (≤30 years) with lymphadenopathy were more likely to have higher prevalence of VCA-IgM antibody (P < 0.01). The prevalence of VCA-IgA and EAD-IgA were 87.0% and 59.2% in NPC patients, respectively, and both were significantly higher (P < 0.001) than that in non-NPC patients. The prevalence of VCA-IgA was 45.4% and 25.6% in SLE patients and patients with other autoimmune diseases, respectively, which were significantly (P < 0.001) and mildly (P = 0.039) higher than their controls. In pediatric SLE patients between 6 and10 years old, the prevalence of VCA-IgG, VCA-IgA and EBNA1-IgG was 100%, 59.5% and 100%, respectively, all being significantly higher than the age (6-10y) related controls (P< 0.01). In the 705 cerebral spinal fluid (CSF) specimens, VCA-IgG, VCA-IgM, VCA-IgA and EAD-IgA were found to be positive in 12.1%, 0.15%, 0.25% and 0.25%, respectively. There were 157 paired specimens (CSF and serum were collected simultaneously) and VCA-IgG was identified as positive in 12.7% of the CSF and 100% of the serum specimens. Around 98% of Chinese patients were infected with EBV before 30 years of age and the highest rate of acute EBV infection were observed in patients under 5 years old. EBV infection was found to be associated with elevated serum liver enzymes, NPC and SLE. Acute anti-EBV antibody was valued for young patients with lymphadenopathy but limited value for CNS neuropathy.

GIT2 Gene: Androgenic Regulation of White Adipose Tissue-Prostate Cancer Interactions

DTIC Science & Technology

2014-05-01

survival of growth factor–expressing ASCs, which enter the systemic circulation and promote PCa progression. An important note is that the prostate...surgical castration and systemic GLIPR1-ΔTM in vivo using VCaP xenograft model: 1. Generate orthotopic VCaP tumors in athymic nude male mice and...effects of systemic GLIPR1-ΔTM on orthotopic VCaP tumor growth and ASCs infiltration profiles ± surgical castration at acute (3d), intermediate (14d

3. INTERIOR, SOUTHEAST VIEW. Vanadium Corporation of America (VCA) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. INTERIOR, SOUTHEAST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Investigation of epstein-barr virus and parvovirus b19 DNA in allogeneic stem cell transplant patients.

PubMed

Atalay, Altay; Gökahmetoğlu, Selma; Durmaz, Süleyman; Kandemir, Idris; Sağlam, Derya; Kaynar, Leylagül; Eser, Bülent; Cetin, Mustafa; Kılıç, Hüseyin

2014-06-01

We aimed to investigate posttransplant Epstein-Barr virus (EBV) and parvovirus B19 DNA in allogeneic stem cell transplant patients between 2009 and 2010. Forty-five adult patients in whom allogeneic stem cell transplantation was performed between April 2009 and November 2010 in the Erciyes University Faculty of Medicine, Department of Internal Medicine, Division of Hematology and Oncology, were included in the study. EBV and parvovirus B19 DNA positivity was investigated by using real-time polymerase chain reaction technique in 135 plasma samples obtained after transplantation at between 1 and 6 months. Pretransplant serological markers of EBV and parvovirus B19 were provided from patient files. In 32 (71.1%) of the patients, EBV antibodies in the pretransplantation period were as follows: anti-EBNA-1 IgG (+), VCA IgM (-), and VCA IgG (+). In 2 patients (4.45%), these antibodies were as follows: anti-EBNA-1 IgG (+), VCA IgM (-), and VCA IgG (-). In 1 patient (2.2%), they were as follows: anti-EBNA-1 IgG (-), VCA IgM (-), and VCA IgG (+). EBV serological markers were negative in 2 (2.2%) out of 45 patients before transplantation. There was low DNA positivity (<600 copies/mL) in 4 patients (8.9%), and VCA IgM was negative and VCA IgG was positive in these same 4 patients. In spite of low viral load, there were no symptoms related to EBV, and posttransplant lymphoproliferative disorder (PTLD) did not occur. While in 44 (99.7%) of 45 patients parvovirus B19 IgM was negative and IgG was positive, parvovirus B19 IgM was positive and IgG was negative in 1 (2.3%) patient. Parvovirus B19 DNA was not identified in any of the samples obtained from these 45 patients. In this study, EBV and parvovirus B19 DNA were investigated in allogeneic stem cell transplant patients. None of the patients developed PTLD and parvovirus B19 DNA positivity was not detected. However, this issue needs to be further evaluated in prospective, multicenter studies with larger series of patients.

Vascularized Composite Allografts: Procurement, Allocation, and Implementation.

PubMed

Rahmel, Axel

Vascularized composite allotransplantation is a continuously evolving area of modern transplant medicine. Recently, vascularized composite allografts (VCAs) have been formally classified as 'organs'. In this review, key aspects of VCA procurement are discussed, with a special focus on interaction with the procurement of classical solid organs. In addition, options for a matching and allocation system that ensures VCA donor organs are allocated to the best-suited recipients are looked at. Finally, the different steps needed to promote VCA transplantation in society in general and in the medical community in particular are highlighted.

Site-Specific Immunosuppression in Vascularized Composite Allotransplantation: Prospects and Potential

PubMed Central

Schnider, Jonas T.; Weinstock, Matthias; Plock, Jan A.; Solari, Mario G.; Venkataramanan, Raman; Zheng, Xin Xiao; Gorantla, Vijay S.

2013-01-01

Skin is the most immunogenic component of a vascularized composite allograft (VCA) and is the primary trigger and target of rejection. The skin is directly accessible for visual monitoring of acute rejection (AR) and for directed biopsy, timely therapeutic intervention, and management of AR. Logically, antirejection drugs, biologics, or other agents delivered locally to the VCA may reduce the need for systemic immunosuppression with its adverse effects. Topical FK 506 (tacrolimus) and steroids have been used in clinical VCA as an adjunct to systemic therapy with unclear beneficial effects. However, there are no commercially available topical formulations for other widely used systemic immunosuppressive drugs such as mycophenolic acid, sirolimus, and everolimus. Investigating the site-specific therapeutic effects and efficacy of systemically active agents may enable optimizing the dosing, frequency, and duration of overall immunosuppression in VCA with minimization or elimination of long-term drug-related toxicity. PMID:23476677

Wave2 activates serum response element via its VCA region and functions downstream of Rac.

PubMed

Ishiguro, Kazuhiro; Cao, Zhifang; Ilasca, Marco Lopez; Ando, Takafumi; Xavier, Ramnik

2004-12-10

WAVE2 is a member of the WASP/WAVE family of protein effectors of actin reorganization and cell movement. In this report, we demonstrate that WAVE2 overexpression induces serum response element (SRE) activation through serum response factor. A WAVE2 mutant lacking the VCA region did not induce SRE activation and actin polymerization. WAVE2-induced SRE activation was blocked by exposure of cells to Latrunculin A, or overexpression of actin mutant R62D. The DeltaVCA mutant inhibited Rac V12-induced SRE activation, suggesting that WAVE2 lies downstream of Rac. Similar deletion of the VCA domain of WASP attenuated Cdc42 V12-mediated SRE activation, suggesting that WAVE2 acts in relation to Rac as WASP acts in relation to Cdc42. WAVE2 overexpression did not activate NF-kappaB.

First-principles study of the effects of Silicon doping on the Schottky barrier of TiSi2/Si interfaces

NASA Astrophysics Data System (ADS)

Wang, Han; Silva, Eduardo; West, Damien; Sun, Yiyang; Restrepo, Oscar; Zhang, Shengbai; Kota, Murali

As scaling of semiconductor devices is pursued in order to improve power efficiency, quantum effects due to the reduced dimensions on devices have become dominant factors in power, performance, and area scaling. In particular, source/drain contact resistance has become a limiting factor in the overall device power efficiency and performance. As a consequence, techniques such as heavy doping of source and drain have been explored to reduce the contact resistance, thereby shrinking the width of depletion region and lowering the Schottky barrier height. In this work, we study the relation between doping in Silicon and the Schottky barrier of a TiSi2/Si interface with first-principles calculation. Virtual Crystal Approximation (VCA) is used to calculate the average potential of the interface with varying doping concentration, while the I-V curve for the corresponding interface is calculated with a generalized one-dimensional transfer matrix method. The relation between substitutional and interstitial Boron and Phosphorus dopant near the interface, and their effect on tuning the Schottky barrier is studied. These studies provide insight to the type of doping and the effect of dopant segregation to optimize metal-semiconductor interface resistance.

First principles study of Al and C-doped MgB2: evolution of two gaps and critical temperature

NASA Astrophysics Data System (ADS)

de La Peña-Seaman, Omar; de Coss, Romeo; Heid, Rolf; Bohnen, Klaus-Peter

2008-03-01

We have studied the electron-phonon and superconducting properties of the Mg1-xAlxB2 and MgB2(1-x)C2x alloys within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloys. For both systems, the Eliashberg spectral function (2̂F(φ)) and the electron-phonon coupling parameter (λ) have been calculated in the two band model (σ,π) for several concentrations until x(Al)=0.55 and x(C)=0.175. Using the calculated 2̂ijF(φ) and a diagonal expression for the Coulomb pseudopotential matrix, &*circ;, we solved numerically the Eliashberg gap equations in the two band model without interband scattering. We reproduce the experimental decreasing behavior of δσ(x), δπ(x), and Tc(x) for both alloy systems. The role of the interband scattering in the observed behavior of the superconducting gaps and Tc in the Al- and C-MgB2 alloys is discussed. This research was supported by Consejo Nacional de Ciencia y Tecnolog'ia (Conacyt) under Grant No. 43830-F.

A hospital based pilot study on Epstein-Barr virus in suspected infectious mononucleosis pediatric patients in India.

PubMed

Janani, Madhuravasal Krishnan; Malathi, Jambulingam; Appaswamy, Andal; Singha, Nishi Rani; Madhavan, Hajib Nariharirao

2015-10-29

Infectious mononucleosis (IM) caused by the Epstein-Barr virus (EBV) is commonly diagnosed by detection of antibodies in the patient's sera. Differentiation of acute from chronic and differential diagnosis of EBV-induced IM from IM-like syndrome caused by human cytomegalovirus (CMV) is important. The objective of this study was to standardize and use polymerase chain reaction (PCR) for diagnosis of EBV and evaluate it against enzyme-linked immunosorbent assay (ELISA). ELISA for detection of IgM and IgG antibodies to viral capsid antigen (VCA) and PCR targeting the VCA and EBNA1 gene of EBV and mtrII gene of CMV were performed on180 peripheral blood samples collected from 180 patients with suspected IM. The analytical sensitivity of PCR was evaluated against that of ELISA. Using the standard serological profile as the reference, the EBV-VCA gene was detected in 41 (95%) of 45 samples collected from patients with early primary infections, in 41 (54%) of 75 with recent primary infections, and in7 (17%) of 39 with past infections. The result of VCA PCR was statistically significant in virus detection during early or primary stage of infection. Nineteen (49%) EBV-seropositive samples were positive for CMV by PCR. All control samples tested negative for both VCA and EBNA1by PCR. VCA PCR is sensitive for the detection of EBV DNA in the early or primary stage of infection and can be considered a reliable method to rule out the cross-reactivity and differential diagnosis of EBV-induced IM from IM-like syndrome.

Attachment anxiety is related to Epstein–Barr virus latency

PubMed Central

Fagundes, Christopher P.; Jaremka, Lisa M.; Glaser, Ronald; Alfano, Catherine M.; Povoski, Stephen P.; Lipari, Adele M.; Agnese, Doreen M.; Yee, Lisa D.; Carson, William E.; Farrar, William B.; Malarkey, William B.; Chen, Min; Kiecolt-Glaser, Janice K.

2015-01-01

Attachment theory provides a framework for understanding individual differences in chronic interpersonal stress. Attachment anxiety, a type of relationship insecurity characterized by worry about rejection and abandonment, is a chronic interpersonal stressor. Stress impacts cellular immunity, including herpes-virus reactivation. We investigated whether attachment anxiety was related to the expression of a latent herpesvirus, Epstein–Barr virus (EBV), when individuals were being tested for breast or colon cancer and approximately 1 year later. Participants (N = 183) completed a standard attachment questionnaire and provided blood to assess EBV viral capsid antigen (VCA) IgG antibody titers. Individuals with more attachment anxiety had higher EBV VCA IgG antibody titers than those with less attachment anxiety. The strength of the association between attachment anxiety and antibody titers was the same at both assessments. This study is the first to show an association between latent herpesvirus reactivation and attachment anxiety. Because elevated herpesvirus antibody titers reflect poorer cellular immune system control over the latent virus, these data suggest that high attachment anxiety is associated with cellular immune dysregulation. PMID:24945717

IGF-1 and Chondroitinase ABC Augment Nerve Regeneration after Vascularized Composite Limb Allotransplantation.

PubMed

Kostereva, Nataliya V; Wang, Yong; Fletcher, Derek R; Unadkat, Jignesh V; Schnider, Jonas T; Komatsu, Chiaki; Yang, Yang; Stolz, Donna B; Davis, Michael R; Plock, Jan A; Gorantla, Vijay S

2016-01-01

Impaired nerve regeneration and inadequate recovery of motor and sensory function following peripheral nerve repair remain the most significant hurdles to optimal functional and quality of life outcomes in vascularized tissue allotransplantation (VCA). Neurotherapeutics such as Insulin-like Growth Factor-1 (IGF-1) and chondroitinase ABC (CH) have shown promise in augmenting or accelerating nerve regeneration in experimental models and may have potential in VCA. The aim of this study was to evaluate the efficacy of low dose IGF-1, CH or their combination (IGF-1+CH) on nerve regeneration following VCA. We used an allogeneic rat hind limb VCA model maintained on low-dose FK506 (tacrolimus) therapy to prevent rejection. Experimental animals received neurotherapeutics administered intra-operatively as multiple intraneural injections. The IGF-1 and IGF-1+CH groups received daily IGF-1 (intramuscular and intraneural injections). Histomorphometry and immunohistochemistry were used to evaluate outcomes at five weeks. Overall, compared to controls, all experimental groups showed improvements in nerve and muscle (gastrocnemius) histomorphometry. The IGF-1 group demonstrated superior distal regeneration as confirmed by Schwann cell (SC) immunohistochemistry as well as some degree of extrafascicular regeneration. IGF-1 and CH effectively promote nerve regeneration after VCA as confirmed by histomorphometric and immunohistochemical outcomes.

Acute rejection in vascularized composite allotransplantation.

PubMed

Fischer, Sebastian; Lian, Christine G; Kueckelhaus, Maximilian; Strom, Terry B; Edelman, Elazer R; Clark, Rachel A; Murphy, George F; Chandraker, Anil K; Riella, Leonardo V; Tullius, Stefan G; Pomahac, Bohdan

2014-12-01

Acute rejection is the most common complication after vascularized composite allotransplantation (VCA). This review provides a state-of-the-art analysis of prevention, diagnosis and treatment of acute rejection episodes and highlights recent findings with the potential to improve patient care and enhance understanding of the underlying biologic processes. Recent reports suggest that maintenance immunosuppression dose reduction and steroid withdrawal are realistic goals in VCA, despite the known high immunogenicity of the skin component. It appears that utilization of sentinel flaps, in-depth histological analyses and application of novel biomarkers have facilitated early diagnosis and characterization of acute rejection episodes, leading to timely institution of appropriate therapy. The successful management of the first highly sensitized face transplant recipient suggests the possibility of carefully considering these high-risk VCA candidates for transplantation. Acute rejection is higher in VCA than in any other organ in the field of transplantation, although most episodes are controlled by high-dose steroids and optimization of maintenance immunosuppression. Because of limitations in patient number and the duration of follow-up, the long-term safety and effectiveness of VCA remain unclear. Moreover, the tests currently used to diagnose acute rejection are of limited value. Better diagnostic tools and a better understanding of the immunologic events during acute rejection are therefore needed to improve diagnosis, treatment and outcomes of this life-changing restorative surgery.

Comparison of three different serological techniques for primary diagnosis and monitoring of nasopharyngeal carcinoma in two age groups from Tunisia.

PubMed

Karray, H; Ayadi, W; Fki, L; Hammami, A; Daoud, J; Drira, M M; Frikha, M; Jlidi, R; Middeldorp, J M

2005-04-01

Nasopharyngeal carcinoma (NPC) in Tunisia is characterized by its bimodal age distribution involving juvenile patients of 10-24 years and adult patients of 40-60 years. Three serological techniques were compared for primary diagnosis (N = 117) and post-treatment monitoring (N = 21) of NPC patients separated in two age groups. Immunofluorescence assay (IFA) was used as the "gold standard" for detection of IgG and IgA antibodies reactive with Epstein-Barr virus (EBV) early (EA) and viral capsid (VCA) antigens. Results were compared with ELISA measuring IgG and IgA antibody reactivity to defined EBNA1, EA, and VCA antigens. Immunoblot was used to reveal the molecular diversity underlying the anti-EBV IgG and IgA antibody responses. The results indicate that young NPC patients have significantly more restricted anti-EBV IgG and IgA antibody responses with aberrant IgG VCA/EA levels in 78% compared to 91.7% in elder patients. IgA VCA/EA was detected in 50% of young patients versus 89.4% for the elder group (P < 0.001). Immunoblot revealed a reduced overall diversity of EBV antigen recognition for both IgG and IgA in young patients. A good concordance was observed between ELISA and IFA for primary NPC diagnosis with 81-91% overall agreement. Even better agreement (95-100%) was found for antibody changes during follow-up monitoring, showing declining reactivity in patients in remission and increasing reactivity in patients with persistent disease or relapse. ELISA for IgA anti-VCA-p18 and immunoblot proved most sensitive for predicting tumor relapse. VCA-p18 IgA ELISA seems suitable for routine diagnosis and early detection of NPC complication. (c) 2005 Wiley-Liss, Inc.

Comparison of the prognostic impact of serum anti-EBV antibody and plasma EBV DNA assays in nasopharyngeal carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Twu, C.-W.; Department of Otorhinolaryngology, Taichung Veterans General Hospital, Taichung; Wang, W.-Y.

Purpose: Nasopharyngeal carcinoma (NPC) has been proven as an Epstein-Barr virus (EBV)-associated cancer. Serum anti-EBV antibodies and plasma EBV DNA have been investigated as surrogate markers for NPC. A comparison of the prognostic impacts of both assays has never been reported. Methods and Materials: Paired serum and plasma samples from 114 previously untreated NPC patients were collected and subjected to an immunofluorescence assay for immunoglobulin (Ig)A and IgG antibodies against the viral capsid antigen (VCA) and a real-time quantitative polymerase chain reaction assay for EBV DNA measurement. The effects of both assays on patient prognosis were thoroughly investigated. Results: Relapsedmore » patients had significantly higher pretreatment EBV DNA concentration than patients without relapse (p 0.0006). No associations of VCA-IgA (p = 0.9669) or VCA-IgG (p = 0.6125) were observed between patients with and without relapse. The 4-year overall survival (60.3% vs. 93.1%, p < 0.0001) and relapse-free survival rates (54.4% vs. 77.9%, p = 0.0009) were significantly lower in patients with higher pretreatment EBV DNA load than in those with lower EBV DNA load. Patients with persistently detectable EBV DNA after treatment had significantly worse 4-year overall (30.8% vs. 84.6%, p < 0.0001) and relapse-free survival rates (15.4% vs. 74.0%, p < 0.0001) than those with undetectable EBV DNA. The VCA-IgA and VCA-IgG titer could not predict survivals (all p > 0.1). Cox multivariate analyses also showed the same results. Conclusion: Plasma EBV DNA is superior to serum EBV VCA antibodies in prognostic predictions for NPC.« less

Moral Development and Ethical Decision-Making: Theory and Faddism.

ERIC Educational Resources Information Center

Shaver, James P.

The author is concerned that teaching strategies based on the values clarification approach (VCA) and on Kohlberg's stage theory of moral development might be premature. The VCA has been adopted widely despite concerns about threats to privacy of participating students, infringement on rights of parents to shape their children's values, and…

Comparison of two automated instruments for Epstein-Barr virus serology in a large adult hospital and implementation of an Epstein-Barr virus nuclear antigen-based testing algorithm.

PubMed

Al Sidairi, Hilal; Binkhamis, Khalifa; Jackson, Colleen; Roberts, Catherine; Heinstein, Charles; MacDonald, Jimmy; Needle, Robert; Hatchette, Todd F; LeBlanc, Jason J

2017-11-01

Serology remains the mainstay for diagnosis of Epstein-Barr virus (EBV) infection. This study compared two automated platforms (BioPlex 2200 and Architect i2000SR) to test three EBV serological markers: viral capsid antigen (VCA) immunoglobulins of class M (IgM), VCA immunoglobulins of class G (IgG) and EBV nuclear antigen-1 (EBNA-1) IgG. Using sera from 65 patients at various stages of EBV disease, BioPlex demonstrated near-perfect agreement for all EBV markers compared to a consensus reference. The agreement for Architect was near-perfect for VCA IgG and EBNA-1 IgG, and substantial for VCA IgM despite five equivocal results. Since the majority of testing in our hospital was from adults with EBNA-1 IgG positive results, post-implementation analysis of an EBNA-based algorithm showed advantages over parallel testing of the three serologic markers. This small verification demonstrated that both automated systems for EBV serology had good performance for all EBV markers, and an EBNA-based testing algorithm is ideal for an adult hospital.

WAVE2 is regulated by multiple phosphorylation events within its VCA domain

PubMed Central

Pocha, Shirin M; Cory, Giles O

2009-01-01

The (Wiskott-Aldrich Syndrome Protein)-family verprolin homologous protein (WAVE) family of proteins occupies a pivotal position in the cell, converting extracellular signals into the formation of branched filamentous (F) actin structures. WAVE proteins contain a verprolin central acidic (VCA) domain at their C-terminus, responsible for binding to and activating the Arp2/3 complex, which in-turn nucleates the formation of new actin filaments. Here we identify five Casein Kinase 2 (CK2) phosphorylation sites within the VCA domain of WAVE2, serines 482, 484, 488, 489, and 497. Phosphorylation of these sites is required for a high affinity interaction with the Arp2/3 complex. Phosphorylation of ser 482 and 484 specifically inhibits the activation of the Arp2/3 complex by the WAVE2 VCA domain, but has no effect on the affinity for the Arp2/3 complex when the other phosphorylation sites are occupied. We demonstrate phosphorylation of all five sites on endogenous WAVE2 and show that their mutation to non-phosphorylatable alanine residues inhibits WAVE2 function in vivo, inhibiting cell ruffling and disrupting the integrity of the leading edge of migrating cells. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. PMID:19012317

WAVE2 is regulated by multiple phosphorylation events within its VCA domain.

PubMed

Pocha, Shirin M; Cory, Giles O

2009-01-01

The (Wiskott-Aldrich Syndrome Protein)-family verprolin homologous protein (WAVE) family of proteins occupies a pivotal position in the cell, converting extracellular signals into the formation of branched filamentous (F) actin structures. WAVE proteins contain a verprolin central acidic (VCA) domain at their C-terminus, responsible for binding to and activating the Arp2/3 complex, which in-turn nucleates the formation of new actin filaments. Here we identify five Casein Kinase 2 (CK2) phosphorylation sites within the VCA domain of WAVE2, serines 482, 484, 488, 489, and 497. Phosphorylation of these sites is required for a high affinity interaction with the Arp2/3 complex. Phosphorylation of ser 482 and 484 specifically inhibits the activation of the Arp2/3 complex by the WAVE2 VCA domain, but has no effect on the affinity for the Arp2/3 complex when the other phosphorylation sites are occupied. We demonstrate phosphorylation of all five sites on endogenous WAVE2 and show that their mutation to non-phosphorylatable alanine residues inhibits WAVE2 function in vivo, inhibiting cell ruffling and disrupting the integrity of the leading edge of migrating cells. (c) 2008 Wiley-Liss, Inc.

Isothermal Titration Calorimeter For Research And Education (DURIP-10)

DTIC Science & Technology

2011-05-12

Plamen Atanassov, University of New Mexico , Shelley Minteer, Saint Louis University, and Scott Calabrese-Barton, Michigan State University. The...associated proteins will also be explored as targets including the ricin toxin B, cholera toxin B, and botulinum neurotoxin type E. The binding...domain from V. cholerae called VCA0042/PlzD. These measurements showed that cdG binding to VCA0042 is entropically unfavorable. They also

VASCULARIZED COMPOSITE ALLOGRAFT TRANSPLANT SURVIVAL IN MINIATURE SWINE: IS MHC TOLERANCE SUFFICIENT FOR ACCEPTANCE OF EPIDERMIS?

PubMed Central

Cetrulo, Curtis L.; Torabi, Radbeh; Scalea, Joseph R.; Shimizu, Akira; Leto Barone, Angelo A.; Gillon, Brad C.; Tasaki, Masayuki; Leonard, David A.; Cormack, Taylor A.; Villani, Vincenzo; Randolph, Mark A.; Sachs, David H.; Yamada, Kazuhiko

2014-01-01

Background We have previously reported that MGH miniature swine which had accepted class-I mismatched kidneys long-term (LT) following 12 days of high dose Cyclosporine (CyA), uniformly accepted donor-MHC matched kidneys without immunosuppression but rejected donor-MHC matched split-thickness skin grafts (STSG) by day 25, without changes in renal graft function or anti-donor in vitro responses. We have now tested whether this “split tolerance” would also be observed for the primarily-vascularized skin of vascularized composite allografts (VCAs). Methods Group 1 animals (n=3) received donor-MHC matched VCAs <70 days following primary kidney transplant (KTx). Group 2 animals (n=3) received a second donor-matched t KTx followed by a donor-matched VCA >200 days after primary KTx. Results Animals in Group 1 lost the epidermis on days 28, 30, and 40, with all other components of the VCAs remaining viable. Histology showed cellular infiltration localized to dermal-epidermal junction. One of 3 recipients of VCAs including epidermis in Group 2 accepted all components of the VCAs (>200 days). The other two recipients lost only the epidermis at day 45 and 85, with survival of the remainder of the VCA long-term. Conclusions All tissues of a VCA are accepted long-term on animals tolerant of class-I mismatched kidneys, with the exception of epidermis, the survival of which is markedly prolonged compared to STSG, but not indefinite. Exposure of tolerant animals to second donor-matched kidneys prior to VCA increases the longevity of the VCA epidermis, suggesting an increase in the immunomodulatory mechanisms associated with tolerance of the kidney. PMID:24056624

Ventral CA3 Activation Mediates Prophylactic Ketamine Efficacy Against Stress-Induced Depressive-like Behavior.

PubMed

Mastrodonato, Alessia; Martinez, Randy; Pavlova, Ina P; LaGamma, Christina T; Brachman, Rebecca A; Robison, Alfred J; Denny, Christine A

2018-02-23

We previously reported that a single injection of ketamine prior to stress protects against the onset of depressive-like behavior and attenuates learned fear. However, the molecular pathways and brain circuits underlying ketamine-induced stress resilience are still largely unknown. Here, we tested whether prophylactic ketamine administration altered neural activity in the prefrontal cortex and/or hippocampus. Mice were injected with saline or ketamine (30 mg/kg) 1 week before social defeat. Following behavioral tests assessing depressive-like behavior, mice were sacrificed and brains were processed to quantify ΔFosB expression. In a second set of experiments, mice were stereotaxically injected with viral vectors into ventral CA3 (vCA3) in order to silence or overexpress ΔFosB prior to prophylactic ketamine administration. In a third set of experiments, ArcCreER T2 mice, a line that allows for the indelible labeling of neural ensembles activated by a single experience, were used to quantify memory traces representing a contextual fear conditioning experience following prophylactic ketamine administration. Prophylactic ketamine administration increased ΔFosB expression in the ventral dentate gyrus and vCA3 of social defeat mice but not of control mice. Transcriptional silencing of ΔFosB activity in vCA3 inhibited prophylactic ketamine efficacy, while overexpression of ΔFosB mimicked and occluded ketamine's prophylactic effects. In ArcCreER T2 mice, ketamine administration altered memory traces representing the contextual fear conditioning experience in vCA3 but not in the ventral dentate gyrus. Our data indicate that prophylactic ketamine may be protective against a stressor by altering neural activity, specifically the neural ensembles representing an individual stressor in vCA3. Copyright © 2018 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Comparison of penetration and metabolism of [3H]diacetoxyscirpenol, [3H]verrucarin A and [3H]T-2 toxin in skin.

PubMed

Kemppainen, B W; Riley, R T; Biles-Thurlow, S

1987-05-01

The purpose of this research was to determine the rate of cutaneous penetration and metabolism of [3H]diacetoxyscirpenol (DAS) and [3H]verrucarin A (VCA) and compare these values to previously determined values for [3H]T-2 toxin (T-2), to compare the cutaneous penetration and metabolism of DAS in human and guinea-pig skin, and to compare the effects of dose and of two vehicles, methanol and dimethylsulphoxide (DMSO), on penetration rates. DAS or VCA was applied to the epidermal surface of excised skin, and the receptor fluid bathing the dermal surface was sampled periodically for 48 hr. Whether the applied dose (581 ng/cm2) was dissolved in methanol or DMSO, the rate of penetration through human skin was lower for VCA than for DAS or T-2, the rates for the two latter compounds being similar at this dose. Metabolism of DAS occurred during penetration through excised human skin and did not occur in the receptor fluid as a result of enzymes leaching out of the skin. VCA appeared to be metabolized by human skin, but this conclusion is tentative because of the relative instability of this compound. DAS penetrated significantly (P less than 0.05) faster through excised guinea-pig skin than through human skin. Metabolism of DAS was greater in human skin than in guinea-pig skin. When compared with methanol, DMSO increased the penetration of DAS and VCA by factors of between 7 and 52. At the low dose (79 ng/cm2) DAS penetrated human and guinea-pig skin significantly (P less than 0.05) faster than T-2 using either vehicle.

Differentially Variable Component Analysis (dVCA): Identifying Multiple Evoked Components using Trial-to-Trial Variability

NASA Technical Reports Server (NTRS)

Knuth, Kevin H.; Shah, Ankoor S.; Truccolo, Wilson; Ding, Ming-Zhou; Bressler, Steven L.; Schroeder, Charles E.

2003-01-01

Electric potentials and magnetic fields generated by ensembles of synchronously active neurons in response to external stimuli provide information essential to understanding the processes underlying cognitive and sensorimotor activity. Interpreting recordings of these potentials and fields is difficult as each detector records signals simultaneously generated by various regions throughout the brain. We introduce the differentially Variable Component Analysis (dVCA) algorithm, which relies on trial-to-trial variability in response amplitude and latency to identify multiple components. Using simulations we evaluate the importance of response variability to component identification, the robustness of dVCA to noise, and its ability to characterize single-trial data. Finally, we evaluate the technique using visually evoked field potentials recorded at incremental depths across the layers of cortical area VI, in an awake, behaving macaque monkey.

Peritransplant Treg-Based Immunomodulation to Improve VCA Outcomes

DTIC Science & Technology

2017-10-01

function as assessed in vitro assays (mean ± SD, n=4/group) using cells analyzed at day 5. (D) Western blots of Foxp3 protein expression in Tregs from...mice and undertaking bisulphite conversion, cloning and sequencing . WT Tregs were largely demethylated at the TSDR site (open circles, Fig. 2...term murine limb vascularized composite allotransplantation (VCA) survival. • Aim 2 - Determine if histone/ protein deacetylase (HDAC) inhibitor

Increased antibody responses to Herpes virus papio (HVP) antigens in pre-lymphomatous baboons (Papio hamadryas) of the Sukhumi high lymphoma stock.

PubMed

Voevodin, A F; Yakovleva, L A; Lapin, B A; Ponomarjeva, T I

1983-11-15

Antibody responses to Herpes virus papio (HVP) antigens were studied in 21 pre-lymphoma baboons (which subsequently died of malignant lymphoma), 21 paired controls, i.e. age-, sex- and population-matched healthy baboons, and 185 randomly selected healthy baboons of the same population. The sera were all collected at the same time and were tested blind in the fixed-cell indirect immunofluorescence test against HVP viral capsid antigen (VCA)-positive, early antigen (EA)-positive cell targets before and after absorption with HVP. Eleven of the pre-lymphoma sera were anti-EA-positive whereas none of the paired controls contained anti-EA. Anti-VCA titers of pre-lymphoma sera were higher than those of paired controls in thirteen cases. Only in four cases were anti-VCA titers of pre-lymphoma sera lower than those of paired controls. Qualitatively, the same results were obtained when anti-VCA and anti-EA titers of pre-lymphoma sera were compared with respective mean population values. The differences between pre-lymphoma group and control groups, especially in the case of anti-EA, were statistically highly significant. Thus, elevated anti-HVP titers in healthy baboons of the Sukhumi lymphoma-prone stock can be considered as a marker of high risk for development of malignant lymphoma.

Effect of Pressure on Some Optical Properties of GaxIn1-xP Semiconductors

NASA Astrophysics Data System (ADS)

Vyas, P.; Gajjar, P.; Jani, A.

2013-06-01

A theoretical procedure is presented for the study of optical properties of ternary alloy GaxIn1-xP. The calculations are based on the pseudopotential formalism in which local potential coupled with the virtual crystal approximation (VCA) is applied to evaluate the effect of pressure on the optical properties like refractive index, electronic polarizability, plasmon energy, dielectric constant and equation of state for gallium concentration x = 0, 0.25, 0.50, 0.75 and 1 of the ternary alloy GaxIn1-xP. To incorporate the screening effect, local field correction functions due to Hartree, Taylor, Ichimaru et al. and Nagy are employed. The refractive index, electronic polarizability and dielectric constant computed for the parent binary compounds GaP and InP are found to be satisfactorily agreeing with the experimental report. It is seen that the refractive index of GaxIn1-xP decreases nonlinearly with the increase in pressure. The results obtained using Hartree's screening functions are not very close to the experimental data as it does not include any exchange and correlation effects. Overall good agreement with the experimental and other theoretical findings confirms the application. The author P. S. Vyas is thankful to UGC, New Delhi, India for providing financial support under minor research project No. F.: 47-651/08(WRO).

Tolerance in Nonhuman Primates by Delayed Mixed Chimerism

DTIC Science & Technology

2015-10-01

Vascularized composite allografts (VCA) are transplants containing multiple tissue types (including bone, muscle, skin, nerves and blood vessels), which offer...15 11. Appendices…………………………………………………………………………………. 15 4 INTRODUCTION Vascularized composite allografts (VCA) are...can be expected to lead to rapid translation into clinical trials. KEYWORDS Vascularized composite allograft, vascularized composite

Epstein-Barr virus and its association with rheumatoid arthritis and oral lichen planus.

PubMed

Adtani, Pooja; Malathi, Narasimhan

2015-01-01

Pathogenesis of autoimmune diseases (AD) is one of a multifactorial milieu. A genetic predisposition, an immune system failure, hormonal imbalance and environmental factors play important roles. Among the many environmental factors, the role of infection is gaining importance in the pathogenesis of various autoimmune disorders; among them, Epstein-Barr virus (EBV) plays a pivotal role. Literature states an association of various AD with EBV namely multiple sclerosis, autoimmune thyroiditis, systemic lupus erythematous, oral lichen planus (OLP), rheumatoid arthritis (RA), autoimmune hepatitis, Sjögren's syndrome and Kawasaki disease; among these, the most commonly occurring are OLP and RA. Considering the frequency of occurrences, our aim was to perform a qualitative analysis of EBV viral capsid antigen (EBV VCA) IgG in the sera of patients with RA, OLP and establish a comparison with normal. In-vitro experiment in a research laboratory. Five-milliliter blood sample was collected from 25 patients diagnosed with RA and OLP. Serum was separated and EBV VCA IgG antibody titer was detected using NovaTec EBV VCA IgG ELISA kit. Chi-square test. Six out of 25 subjects with RA and 4 out of 25 subjects with OLP tested positive for EBV VCA IgG. Both environmental and genetic factors are important contributory components for autoimmune conditions. Screening for viral etiology would improve the efficacy of conventional treatment and reduce the risk of relapses.

Impact of reconstructive transplantation on the future of plastic and reconstructive surgery.

PubMed

Siemionow, Maria

2012-10-01

This article summarizes the current knowledge on the new developing field of reconstructive transplantation. A brief outline of vascularized composite allografts (VCA) such as human hand, face, larynx, and abdominal wall transplants is provided. The clinical applications and indications for these new reconstructive transplantation procedures are outlined. The advantages, disadvantages, and complications and concerns surrounding clinical VCA are discussed. Finally, the impact of reconstructive transplantation on the future of plastic and reconstructive surgery is presented. Copyright © 2012 Elsevier Inc. All rights reserved.

Outcomes after hand and upper extremity transplantation.

PubMed

Shores, Jaimie T; Malek, Veronika; Lee, W P Andrew; Brandacher, Gerald

2017-05-01

Hand and upper extremity transplantation (HUET) has emerged as the most frequently performed reconstructive procedure in the burgeoning field of vascularized composite allotransplantation (VCA). VCA refers to a form of transplant with multiple tissue types that represents a viable treatment option for devastating injuries where conventional reconstruction would be unable to restore form and function. As hand transplantation becomes increasingly more common, discussions on advantages and disadvantages of the procedure seem to intensify. Despite encouraging functional outcomes, current immunosuppressive regimens with their deleterious side-effect profile remain a major concern for a life-changing but not life-saving type of transplant. In addition, a growing number of recipients with progressively longer follow-up prompt the need to investigate potential long-term sequelae, such as chronic rejection. This review will discuss the current state of HUET, summarizing outcome data on graft survival, motor and sensory function, as well as immunosuppressive treatment. The implications of these findings for VCA in terms of achievements and challenges ahead will then be discussed.

Requirement of the basic region of N-WASP/WAVE2 for actin-based motility.

PubMed

Suetsugu, S; Miki, H; Yamaguchi, H; Takenawa, T

2001-04-06

WASP family proteins activate nucleation by the Arp2/3 complex, inducing rapid actin polymerization in vitro. Although the C-terminal portion of WASP family proteins (VCA) activates nucleation by the Arp2/3 complex in pure systems, we find that this fragment lacks activity in cell extracts. Thus, polystyrene beads coated with VCA did not move in brain cytosol, while beads coated with N-WASP or WAVE2 did move. The basic clusters between the WH1 domain and the CRIB domain of N-WASP were critical for movement since beads coated with N-WASP or WAVE2 constructs missing the basic clusters (Delta basic) also did not move. Furthermore, VCA and N-WASP/WAVE2 Delta basic constructs were much less able than wild-type N-WASP and WAVE2 to induce actin polymerization in cytosol. All of the proteins, with or without the basic domain, were potent activators of nucleation by purified Arp2/3 complex. Copyright 2001 Academic Press.

From virtual clustering analysis to self-consistent clustering analysis: a mathematical study

NASA Astrophysics Data System (ADS)

Tang, Shaoqiang; Zhang, Lei; Liu, Wing Kam

2018-03-01

In this paper, we propose a new homogenization algorithm, virtual clustering analysis (VCA), as well as provide a mathematical framework for the recently proposed self-consistent clustering analysis (SCA) (Liu et al. in Comput Methods Appl Mech Eng 306:319-341, 2016). In the mathematical theory, we clarify the key assumptions and ideas of VCA and SCA, and derive the continuous and discrete Lippmann-Schwinger equations. Based on a key postulation of "once response similarly, always response similarly", clustering is performed in an offline stage by machine learning techniques (k-means and SOM), and facilitates substantial reduction of computational complexity in an online predictive stage. The clear mathematical setup allows for the first time a convergence study of clustering refinement in one space dimension. Convergence is proved rigorously, and found to be of second order from numerical investigations. Furthermore, we propose to suitably enlarge the domain in VCA, such that the boundary terms may be neglected in the Lippmann-Schwinger equation, by virtue of the Saint-Venant's principle. In contrast, they were not obtained in the original SCA paper, and we discover these terms may well be responsible for the numerical dependency on the choice of reference material property. Since VCA enhances the accuracy by overcoming the modeling error, and reduce the numerical cost by avoiding an outer loop iteration for attaining the material property consistency in SCA, its efficiency is expected even higher than the recently proposed SCA algorithm.

Epstein-Barr virus glycoprotein gH/gL antibodies complement IgA-viral capsid antigen for diagnosis of nasopharyngeal carcinoma

PubMed Central

Tang, Lin-Quan; Zhang, Hua; Li, Yan; Liu, Wan-Li; Zhong, Qian; Zeng, Mu-Sheng; Huang, Xiao-Ming

2016-01-01

To determine whether measuring antibodies against Epstein-Barr virus (EBV) glycoprotein gH/gL in serum could improve diagnostic accuracy in nasopharyngeal carcinoma (NPC) cases, gH/gL expressed in a recombinant baculovirus system was used in an enzyme-linked immunosorbent assay (ELISA) to detect antibodies in two independent cohorts. Binary logistic regression analyses were performed using results from a training cohort (n = 406) to establish diagnostic mathematical models, which were validated in a second independent cohort (n = 279). Levels of serum gH/gL antibodies were higher in NPC patients than in healthy controls (p < 0.001). In the training cohort, the IgA-gH/gL ELISA had a sensitivity of 83.7%, specificity of 82.3% and area under the curve (AUC) of 0.893 (95% CI, 0.862-0.924) for NPC diagnosis. Furthermore, gH/gL maintained diagnostic capacity in IgA-VCA negative NPC patients (sensitivity = 78.1%, specificity = 82.3%, AUC = 0.879 [95% CI, 0.820 - 0.937]). Combining gH/gL and viral capsid antigen (VCA) detection improved diagnostic capacity as compared to individual tests alone in both the training cohort (sensitivity = 88.5%, specificity = 97%, AUC = 0.98 [95% CI, 0.97 - 0.991]), and validation cohort (sensitivity = 91.2%, specificity = 96.5%, AUC = 0.97 [95% CI, 0.951-0.988]). These findings suggest that EBV gH/gL detection complements VCA detection in the diagnosis of NPC and aids in the identification of patients with VCA-negative NPC. PMID:27093005

Outcomes of Solid Organ Transplants After Simultaneous Solid Organ and Vascularized Composite Allograft Procurements: A Nationwide Analysis.

PubMed

Aycart, Mario A; Alhefzi, Muayyad; Sharma, Gaurav; Krezdorn, Nicco; Bueno, Ericka M; Talbot, Simon G; Carty, Matthew J; Tullius, Stefan G; Pomahac, Bohdan

2017-06-01

Current knowledge of the impact of facial vascularized composite allograft (VCA) procurement on the transplantation outcomes of the concomitantly recovered solid organs is limited to isolated case reports and short-term results. Here we report on a nationwide analysis of facial allograft donor surgery experience and long-term outcomes of the concomitantly recovered solid organs and their recipients. There were 10 facial VCA procurements in organ donors between December 2008 and October 2014. We identified the population of subjects who received solid organs from these 10 donors using the Scientific Registry of Transplant Recipients. We retrospectively reviewed operative characteristics, intraoperative parameters, and postoperative outcomes. Six of 10 donor surgeries were performed at outside institutions, all on brain-dead donors. Mean operative duration for facial VCA recovery was 6.9 hours (range, 4-13.25 hours). A total of 36 solid organs were recovered and transplanted into 35 recipients. Survival rates for kidney and liver recipients were 100% and 90% at a median follow-up of 33 and 27.5 months, respectively (range, 6-72 months). Graft survival rates for kidneys and livers were 15 of 16 (94%) and 9 of 10 (90%), respectively. Recipient and graft survival rates for hearts and lungs were 75% (n = 4) and 100% (n = 3) at mean follow-up time of 14.75 and 16 months, respectively. A liver recipient died at 22 months from unknown causes and a heart recipient died of leukemia at 10 months. Facial VCA procurement does not appear to adversely affect the outcomes of transplant recipients of concomitantly recovered solid organ allografts.

Elevated antinuclear antibodies and altered anti-Epstein-Barr virus immune responses.

PubMed

Cuomo, Laura; Cirone, Mara; Di Gregorio, Ana Oliva; Vitillo, Marina; Cattivelli, Marina; Magliocca, Vittoria; Maiorano, Silvana; Meledandri, Marcello; Scagnolari, Carolina; La Rocca, Sebastiano; Trivedi, Pankaj

2015-01-02

It has been shown that Epstein-Barr virus (EBV) is able to alter the immune response towards self-antigens and may enhance risk of autoimmune diseases such as systemic lupus erythematosus (SLE) in genetically predisposed individuals. In this study, we evaluated the specific antibody immune response against EBV in patients with anti-nuclear autoantibodies (ANA) in comparison with ANA-negative healthy controls. For this purpose, 92 patients with an high anti-ANA reactivity with or without concomitant extractable nuclear antigen (ENA) or double stranded DNA (dsDNA) positivity were selected and compared with 146 healthy donors. We found that anti-EBV-VCA and EA IgG concentrations were significantly higher in ANA-positive patients in comparison to the controls (VCA P<0.0001 and EA P<0,03) as well as in those ANA-positive patients that showed a concomitant ENA positivity (P=0.0002). Interestingly, elevated anti-EBNA-1 IgG was found in a group of patients who had anti SSA/Ro antibodies. Anti-VCA IgM Abs were more frequently found in those patients with a very high titer of ANA (P=0.06); moreover detection of anti-VCA IgM/IgG in absence of anti-EBNA-1 IgG was more frequent in the patient than in the control group. Both these conditions correlate with a recent EBV infection or reactivation. The data suggest that EBV, particularly during acute infection or in its reactivation phase, could be involved in the ANA and ENA autoantibody formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Targeting monoamine oxidase A in advanced prostate cancer.

PubMed

Flamand, Vincent; Zhao, Hongjuan; Peehl, Donna M

2010-11-01

Inhibitors of monoamine oxidase A (MAOA), a mitochondrial enzyme that degrades neurotransmitters including serotonin and norepinephrine, are commonly used to treat neurological conditions including depression. Recently, we and others identified high expression of MAOA in normal basal prostatic epithelium and high-grade primary prostate cancer (PCa). In contrast, MAOA is low in normal secretory prostatic epithelium and low-grade PCa. An irreversible inhibitor of MAOA, clorgyline, induced secretory differentiation in primary cultures of normal basal epithelial cells and high-grade PCa. Furthermore, clorgyline inhibited several oncogenic pathways in PCa cells, suggesting clinical value of MAOA inhibitors as a pro-differentiation and anti-oncogenic therapy for high-risk PCa. Here, we extended our studies to a model of advanced PCa, VCaP cells, which were derived from castration-resistant metastatic PCa and express a high level of MAOA. Growth of VCaP cells in the presence or absence of clorgyline was evaluated in vitro and in vivo. Gene expression changes in response to clorgyline were determined by microarray and validated by quantitative real-time polymerase chain reaction. Treatment with clorgyline in vitro inhibited growth and altered the transcriptional pattern of VCaP cells in a manner consistent with the pro-differentiation and anti-oncogenic effects seen in treated primary PCa cells. Src, beta-catenin, and MAPK oncogenic pathways, implicated in androgen-independent growth and metastasis, were significantly downregulated. Clorgyline treatment of mice bearing VCaP xenografts slowed tumor growth and induced transcriptome changes similar to those noted in vitro. Our results support the possibility that anti-depressant drugs that target MAOA might find a new application in treating PCa.

Effect of (E)-5-(2-bromovinyl)-2'-deoxyuridine on several parameters of Epstein-Barr virus infection.

PubMed

Zhang, Z X; Liu, Y X; Chen, H C; Allaudeen, H S; De Clercq, E

1984-01-01

The selective and potent anti-herpesvirus drug, (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdU), has been examined for its inhibitory effects on several parameters of Epstein-Barr virus (EBV) infection in the lymphoblastoid cell lines Raji, P3HR-1, B-95-8 and P3 hybrid cells (a human embryo oropharyngeal cell line fused with a nasopharyngeal carcinoma cell line). At a dosage of 0.03 to 0.1 mM, BVdU caused a marked inhibition of (i) spontaneous viral capsid antigen (VCA) expression in B-95-8 and P3 hybrid cells, (ii) VCA expression and DNA synthesis in B-95-8 cells induced with croton oil and n-butyrate, (iii) early antigen (EA) expression and DNA synthesis in Raji cells superinfected with EBV, and (iv) VCA expression and DNA synthesis in B-95-8 cells superinfected with EBV. In its inhibitory effects on these various parameters of EBV infection, BVdU appears to be comparable to acyclovir [9-(2-hydroxyethoxymethyl)guanine], another selective anti-herpesvirus drug which has been previously recognized as an effective inhibitor of EBV replication.

Pathway of actin filament branch formation by Arp2/3 complex revealed by single-molecule imaging

PubMed Central

Smith, Benjamin A.; Daugherty-Clarke, Karen; Goode, Bruce L.; Gelles, Jeff

2013-01-01

Actin filament nucleation by actin-related protein (Arp) 2/3 complex is a critical process in cell motility and endocytosis, yet key aspects of its mechanism are unknown due to a lack of real-time observations of Arp2/3 complex through the nucleation process. Triggered by the verprolin homology, central, and acidic (VCA) region of proteins in the Wiskott-Aldrich syndrome protein (WASp) family, Arp2/3 complex produces new (daughter) filaments as branches from the sides of preexisting (mother) filaments. We visualized individual fluorescently labeled Arp2/3 complexes dynamically interacting with and producing branches on growing actin filaments in vitro. Branch formation was strikingly inefficient, even in the presence of VCA: only ∼1% of filament-bound Arp2/3 complexes yielded a daughter filament. VCA acted at multiple steps, increasing both the association rate of Arp2/3 complexes with mother filament and the fraction of filament-bound complexes that nucleated a daughter. The results lead to a quantitative kinetic mechanism for branched actin assembly, revealing the steps that can be stimulated by additional cellular factors. PMID:23292935

Effect of WAVE2 phosphorylation on activation of the Arp2/3 complex.

PubMed

Nakanishi, Osamu; Suetsugu, Shiro; Yamazaki, Daisuke; Takenawa, Tadaomi

2007-03-01

Members of the family of WASP-family Verprolin homologous proteins (WAVEs) activate the Arp2/3 complex to induce actin polymerization. The WAVE family comprises three proteins, namely, WAVE1, WAVE2 and WAVE3. Among them, WAVE2 is crucial for activation of the Arp2/3 complex for the formation of branched actin filaments in lamellipodia. Activation of mitogen-activated protein (MAP) kinase signalling results in the phosphorylation of the WAVE family proteins; however, which of the three WAVE proteins is phosphorylated is unclear. We found that in vitro WAVE2 is directly phosphorylated by a MAP kinase, i.e. extracellular signal-regulated kinase (ERK) 2. The proline-rich region and the verprolin, cofilin and acidic (VCA) region of WAVE2 were phosphorylated. Interestingly, the phosphorylated VCA region had a higher affinity for the Arp2/3 complex. However, the phosphorylation of the VCA region resulted in reduced induction of Arp2/3-mediated actin polymerization in vitro. The role of the phosphorylation of the proline-rich region was not determined.

Immunomodulatory Strategies Directed Towards Tolerance of Vascularized Composite Allografts

PubMed Central

Michel, Sebastian G.; Villani, Vincenzo; Muraglia, Glenn M. La; Torabi, Radbeh; Leonard, David A.; Randolph, Mark A.; Colvin, Robert B.; Yamada, Kazuhiko; Madsen, Joren C.; Cetrulo, Curtis L.; Sachs, David H.

2015-01-01

Background Achieving tolerance of vascularized composite allografts (VCAs) would improve the risk-to-benefit ratio in patients who undergo this life-enhancing, though not life-saving, transplant. Kidney co-transplantation along with a short course of high-dose immunosuppression enables tolerance of heart allografts across a full MHC mismatch. In this study, we investigated whether tolerance of VCA across full MHC disparities could be achieved in animals already tolerant of heart and kidney allografts. Methods Miniature swine that were tolerant of heart and/or kidney allografts long-term underwent transplantation of myocutaneous VCA across the same MHC barrier. Prior to VCA transplant, Group 1 (n=3) underwent Class I-mismatched kidney transplantation; Group 2 (n=3) underwent two sequential Class I-mismatched kidney transplantations; Group 3 (n=2) underwent haploidentical MHC-mismatched heart/kidney transplantation; and Group 4 (n=2) underwent full MHC-mismatched heart/kidney transplantation. Results All three animals in Group 1 and two of three animals in Group 2 showed skin rejection ≤85 days; one animal in Group 2 showed prolonged skin survival >200 days. Animals in Groups 3 and 4 showed skin rejection ≤30 days and regained in vitro evidence of donor responsiveness. Conclusion This is the first pre-clinical study in which hearts, kidneys, and VCAs have been transplanted into the same recipient. Despite VCA rejection, tolerance of heart and kidney allografts was maintained. These results suggest that regulatory tolerance of skin is possible but not generally achieved by the same level of immunomodulation that is capable of inducing tolerance of heart and kidney allografts. Achieving tolerance of skin may require additional immunomodulatory therapies. PMID:25757218

Difficulties encountered at the beginning of professional life: results of a 2003 pilot survey among undergraduate students in Paris Rene Descartes University (France).

PubMed

Benbelaïd, R; Dot, D; Levy, G; Eid, N

2006-11-01

In addition to dental hospital clinical activity, dental students at Paris Rene Descartes University have the opportunity in their final year of study to practise clinically in a dental office, as associates. This paper outlines a pilot, experimental study designed to assess student reaction to this Vocational Clinical Activity (VCA) in order to identify relevant weaknesses of the undergraduate programme. Using questionnaires, data were collected for each of the following clinical or management skills: clinical difficulty, therapeutic decision-making, patient/practitioner relationship, time management, administrative matters and technical problems. Students were asked to rank each item in order of difficulty (1, high level to 6, low level). A high response rate was observed (90%) among the 50 undergraduate VCA students. The results pointed out three main difficulties encountered by undergraduate students during the VCA: time management (90% of the students), administrative matters (85% of the students) and clinical decision-making (80% of the students). These preliminary results need further investigation. However, they give us the incentive to carry on with this type of assessment and to extend it to young, qualified colleagues' perceptions and to other French Universities.

Assessment of Polarimetric SAR Interferometry for Improving Ship Classification based on Simulated Data

PubMed Central

Margarit, Gerard; Mallorqui, Jordi J.

2008-01-01

This paper uses a complete and realistic SAR simulation processing chain, GRECOSAR, to study the potentialities of Polarimetric SAR Interferometry (POLInSAR) in the development of new classification methods for ships. Its high processing efficiency and scenario flexibility have allowed to develop exhaustive scattering studies. The results have revealed, first, vessels' geometries can be described by specific combinations of Permanent Polarimetric Scatterers (PePS) and, second, each type of vessel could be characterized by a particular spatial and polarimetric distribution of PePS. Such properties have been recently exploited to propose a new Vessel Classification Algorithm (VCA) working with POLInSAR data, which, according to several simulation tests, may provide promising performance in real scenarios. Along the paper, explanation of the main steps summarizing the whole research activity carried out with ships and GRECOSAR are provided as well as examples of the main results and VCA validation tests. Special attention will be devoted to the new improvements achieved, which are related to simulations processing a new and highly realistic sea surface model. The paper will show that, for POLInSAR data with fine resolution, VCA can help to classify ships with notable robustness under diverse and adverse observation conditions. PMID:27873954

Studies Introducing Costimulation Blockade for Vascularized Composite Allografts in Non-Human Primates

PubMed Central

Freitas, AM; Samy, KP; Farris, AB; Leopardi, FV; Song, M; Stempora, L; Strobert, EA; Jenkins, JA; Kirk, AD; Cendales, LC

2016-01-01

Vascularized composite allografts (VCAs) are technically feasible. Similar to other organ transplants, VCAs are hampered by the toxicity and incomplete efficacy associated with conventional immunosuppression. Complications attributable to calcineurin inhibitors remain prevalent in the clinical cases reported to date, and these loom particularly large given the non-lifesaving nature of VCAs. Additionally, acute rejection remains almost ubiquitous, albeit controllable with current agents. Costimulation blockade offers the potential to provide prophylaxis from rejection without the adverse consequences of calcineurin-based regimens. In this study, we used a non-human-primate model of VCA in conjunction with immunosuppressive regimens containing combinations of B7-specific costimulation blockade with and without adhesion blockade with LFA3-Ig to determine what adjunctive role these agents could play in VCA transplantation when combined with more conventional agents. Compared to tacrolimus, the addition of belatacept improved rejection free allograft survival. The combination with LFA3-Ig reduced CD2hi memory T cells, however did not provide additional protection against allograft rejection and hindered protective immunity. Histology paralleled clinical histopathology and Banff grading. These data provide the basis for the study of costimulation blockade in VCA in a relevant preclinical model. PMID:26139552

Using Saliency-Weighted Disparity Statistics for Objective Visual Comfort Assessment of Stereoscopic Images

NASA Astrophysics Data System (ADS)

Zhang, Wenlan; Luo, Ting; Jiang, Gangyi; Jiang, Qiuping; Ying, Hongwei; Lu, Jing

2016-06-01

Visual comfort assessment (VCA) for stereoscopic images is a particularly significant yet challenging task in 3D quality of experience research field. Although the subjective assessment given by human observers is known as the most reliable way to evaluate the experienced visual discomfort, it is time-consuming and non-systematic. Therefore, it is of great importance to develop objective VCA approaches that can faithfully predict the degree of visual discomfort as human beings do. In this paper, a novel two-stage objective VCA framework is proposed. The main contribution of this study is that the important visual attention mechanism of human visual system is incorporated for visual comfort-aware feature extraction. Specifically, in the first stage, we first construct an adaptive 3D visual saliency detection model to derive saliency map of a stereoscopic image, and then a set of saliency-weighted disparity statistics are computed and combined to form a single feature vector to represent a stereoscopic image in terms of visual comfort. In the second stage, a high dimensional feature vector is fused into a single visual comfort score by performing random forest algorithm. Experimental results on two benchmark databases confirm the superior performance of the proposed approach.

Transformation of lymphocytes by Herpesvirus papio.

PubMed

Falk, L A; Henle, G; Henle, W; Deinhardt, F; Schudel, A

1977-08-15

Cotton-topped (CT) or white-lipped (WL) marmoset lymphocytes were transformed in vitro with herpesvirus papio (HVP) into permanently growing lymphoblastoid cell lines (LCL). Five of 9 HVP-transformed CT cell lines contained cells with antigens reacting with antibodies to Epstein-Barr virus (EBV) capsid antigen (VCA) and/or to EBV-induced early antigens (EA). None of 12 WL LCL revealed such antigen-producing cells. Cells from both groups of cultures failed to react with antibodies to the EBV-specified nuclear antigen (EBNA). Exposure of baboon circulating lymphocytes to X-irradiated HVP or EBV-carring cells, or to suspensions of EBV resulted in establishment of LCL which all contained VCA and/or EA-positive, but no EBNA-positive cells. Nuclear antigens were undetectable also with anti-VCA-positive sera from baboons, chimpanzees, or other non-human primates. DNA-complementary RNA (cRNA) filter hybridization with EBV cRNA showed that with one exception transformed CT or WL marmoset cells contained at least 1-2 virus genome equivalents per cell, while at least 12-25 virus genome equivalents per cell were detected in transformed baboon cells. These data need confirmation by DNA-DNA reassociation kinetics.

Region-specific roles of the prelimbic cortex, the dorsal CA1, the ventral DG and ventral CA1 of the hippocampus in the fear return evoked by a sub-conditioning procedure in rats.

PubMed

Fu, Juan; Xing, Xiaoli; Han, Mengfi; Xu, Na; Piao, Chengji; Zhang, Yue; Zheng, Xigeng

2016-02-01

The return of learned fear is an important issue in anxiety disorder research since an analogous process may contribute to long-term fear maintenance or clinical relapse. A number of studies demonstrate that mPFC and hippocampus are important in the modulation of post-extinction re-expression of fear memory. However, the region-specific role of these structures in the fear return evoked by a sub-threshold conditioning (SC) is not known. In the present experiments, we first examined specific roles of the prelimbic cortex (PL), the dorsal hippocampus (DH, the dorsal CA1 area in particular), the ventral hippocampus (the ventral dentate gyrus (vDG) and the ventral CA1 area in particular) in this fear return process. Then we examined the role of connections between PL and vCA1 with this behavioral approach. Rats were subjected to five tone-shock pairings (1.0-mA shock) to induce conditioned fear (freezing), followed by three fear extinction sessions (25 tone-alone trials each session). After a post-test for extinction memory, some rats were retrained with the SC procedure to reinstate tone-evoked freezing. Rat groups were injected with low doses of the GABAA agonist muscimol to selectively inactivate PL, DH, vDG, or vCA1 120 min before the fear return test. A disconnection paradigm with ipsilateral or contralateral muscimol injection of the PL and the vCA1 was used to examine the role of this pathway in the fear return. We found that transient inactivation of these areas significantly impaired fear return (freezing): inactivation of the prelimbic cortex blocked SC-evoked fear return in particular but did not influence fear expression in general; inactivation of the DH area impaired fear return, but had no effect on the extinction retrieval process; both ventral DG and ventral CA1 are required for the return of extinguished fear whereas only ventral DG is required for the extinction retrieval. These findings suggest that PL, DH, vDG, and vCA1 all contribute to the fear return and connections between PL and vCA1 may be involved in the modulation of this process. Copyright © 2016 Elsevier Inc. All rights reserved.

Cell-Based Therapies in Vascularized Composite Allotransplantation.

PubMed

Vyas, Krishna S; Mohan, Anita T; Morrison, Shane D; Tran, Duy C; Mardini, Samir

2018-06-26

 Dendritic cells (DCs) are bone marrow-derived, professional antigen-presenting cells with tolerogenic function. The ability of DCs to regulate alloantigen-specific T cell responses and to promote tolerance has aligned them ideally for a role in vascularized composite allotransplantation (VCA). In this study, we summarize the current evidence for DC therapies for tolerance induction to alleviate the requirement for chronic immunosuppression.  A comprehensive and structured review of manuscripts published on VCA was performed using the MEDLINE and PubMed databases. All eligible studies published from the year 2000 to 2017 were included in the final results.  Nineteen original preclinical and clinical studies that employed cell therapy for VCA were included in this review. In vivo DC therapy was found to direct the alloimmune response toward either transplant rejection or tolerance in VCA models. While injection of mature DCs rapidly increases T-cell activity in humans and promotes transplant rejection, the injection of immature DCs acts as an immunosuppressant and inhibits T-cell activity. In addition to immature DCs, mesenchymal stem cells were also found to have a positive effect on allotransplantation of solid organs and bone marrow via cytokine expression which decreases the alloreactive effector lymphocytes and increases CD4+/CD25+/FoxP3 Tregs. Despite the promising findings, the efficacy of cell-based therapies varies greatly across studies, partly due to different methods of cell isolation and purification techniques, source, route and timing of administration, and combination immunosuppressive therapy.  Additional research is needed to evaluate the efficacy and safety of DC and other cell-based therapeutic measures in human allotransplant recipients. Future direction will focus on the development of novel methods to reduce immunosuppression and develop more individualized management, as well as the clinical application of basic research in the mechanisms of immunologic tolerance. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Inhibition of microRNA-500 has anti-cancer effect through its conditional downstream target of TFPI in human prostate cancer.

PubMed

Cai, Bing; Chen, Wei; Pan, Yue; Chen, Hongde; Zhang, Yirong; Weng, Zhiliang; Li, Yeping

2017-07-01

We investigated the prognostic potential and regulatory mechanism of microRNA-500 (miR-500), and human gene of tissue factor pathway inhibitor (TFPI) in prostate cancer. MiR-500 expression was assessed by qRT-PCR in prostate cancer cell lines and primary tumors. Cancer patients' clinicopathological factors and overall survival were analyzed according to endogenous miR-500 level. MiR-500 was downregulated in DU145 and VCaP cells. Its effect on prostate cancer proliferation, invasion in vitro, and tumorigenicity in vivo, were probed. Possible downstream target of miR-500, TFPI was assessed by luciferase assay and qRT-PCR in prostate cancer cells. In miR-500-downregulated DU145 and VCaP cells, TFPI was silenced to see whether it was directly involved in the regulation of miR-500 in prostate cancer. TFPI alone was either upregulated or downregulated in DU145 and VCaP cells. Their effect on prostate cancer development was further evaluated. MiR-500 is upregulated in both prostate cancer cells and primary tumors. In prostate cancer patients, high miR-500 expression is associated with poor prognosis and overall survival. In DU145 and VCaP cells, miR-500 downregulation inhibited cancer proliferation, invasion in vitro, and explant growth in vivo. TFPI was verified to be associated with miR-500 in prostate cancer. Downregulation of TFPI reversed anti-cancer effects of miR-500 downregulation in prostate cancer cells. However, neither TFPI upregulation nor downregulation alone had any functional impact on prostate cancer development. MiR-500 may be a potential biomarker and molecular target in prostate cancer. TFPI may conditionally regulate prostate cancer in miR-500-downregualted prostate cancer cells. © 2017 Wiley Periodicals, Inc.

Influence of Bi-related impurity states on the bandgap and spin-orbit splitting energy of dilute III-V-Bi alloys: InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix

NASA Astrophysics Data System (ADS)

Samajdar, D. P.; Dhar, S.

2016-01-01

Valence Band Anticrossing (VBAC) Model is used to calculate the changes in band structure of Bi containing alloys such as InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix due to the incorporation of dilute concentrations of bismuth. The coupling parameter CBi which gives the magnitude of interaction of Bi impurity states with the LH, HH and SO sub bands in VBAC depends on the increase in the HH/LH related energy level EHH/LH+, location of the Bi related impurity level EBi and valence band offset ΔEVBM between the endpoint compounds in the corresponding III-V-Bi. The reduction in band gap as well as the enhancement of the spin-orbit splitting energy is well explained using this model and the calculated results are compared with the results of Virtual Crystal Approximation (VCA) and Density Functional Theory (DFT) calculations, as well as with the available experimental data and are found to have good agreement. The incorporation of Bi mainly perturbs the valence band due to the interaction of the Bi impurity states with the HH, LH and SO bands. The lowering of the conduction band minimum (CBM) due to VCA is added with the upward movement of the HH/LH bands to get the total reduction in band gap for the bismides. The valence band shifts of 31.9, 32.5, 20.8 and 12.4 meV/at%Bi for InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix respectively constitute 65, 76, 59 and 31% of the total band gap reduction and the rest is the contribution of the conduction band shift. The spin-orbit splitting energy also shows significant increase with the maximum change in InPBi and the minimum in InSbBi. The same is true for Ga containing bismides if we make a comparison with the available values for GaAsBi and GaPBi with that of GaSbBi. It has also been observed that the increase in splitting energy is greater in case of the bismides such as InAsBi, InPBi and GaAsBi than the bismides such as InSbBi and GaSbBi with the parent substrates having higher values of splitting energy. This may be due to the proximity of the Bi related impurity level EBi with the SO bands of InAs, InP and GaAs.

Detection of EBV-DNA in serum samples of an immunosuppressed child during a three years follow-up: association of clinical and PCR data with active infection.

PubMed

Okay, Thelma Suely; Del Negro, Gilda Maria Barbaro; Yamamoto, Lídia; Raiz Júnior, Roberto

2005-01-01

Twenty-four whole blood and serum samples were drawn from an eight year-old heart transplant child during a 36 months follow-up. EBV serology was positive for VCA-IgM and IgG, and negative for EBNA-IgG at the age of five years old when the child presented with signs and symptoms suggestive of acute infectious mononucleosis. After 14 months, serological parameters were: positive VCA-IgG, EBNA-IgG and negative VCA-IgM. This serological pattern has been maintained since then even during episodes suggestive of EBV reactivation. PCR amplified a specific DNA fragment from the EBV gp220 (detection limit of 100 viral copies). All twenty-four whole blood samples yielded positive results by PCR, while 12 out of 24 serum samples were positive. We aimed at analyzing whether detection of EBV-DNA in serum samples by PCR was associated with overt disease as stated by the need of antiviral treatment and hospitalization. Statistical analysis showed agreement between the two parameters evidenced by the Kappa test (value 0.750; p < 0.001). We concluded that detection of EBV-DNA in serum samples of immunosuppressed patients might be used as a laboratory marker of active EBV disease when a Real-Time PCR or another quantitative method is not available.

From N-WASP to WAVE: key molecules for regulation of cortical actin organization.

PubMed

Takenawa, Tadaomi

2005-01-01

We first isolated N-WASP as one of the proteins bound to Ash/Grb2 SH3 domain. This protein has a VCA region (verplorin-like, cofilin-like, acidic region) at the C-terminus, which binds to G-actin and Arp2/3 complex, and several functional domains at the N-terminus, such as WHD (WASP homology domain) and GBD/CRIB domain. N-WASP activates Arp2/3 complex-dependent actin polymerization through the VCA region, leading to filopodium formation. Next, we found WAVE1, WAVE2 and WAVE3. All these proteins have also VCA regions at C-terminal areas and induce membrane ruffle formation. To clarify the different roles of WAVE1 and WAVE2, we established WAVE1- and WAVE2-deficient mouse embryonic fibroblasts (MEFs), because these two WAVEs are expressed in MEF. When wild-type MEFs are stimulated randomly by PDGF, two types of ruffles, peripheral and dorsal, are formed. However, dorsal ruffle formation does not occurin WAVE1-deficient MEFs. In contrast, peripheral ruffle formation is diminished in WAVE2-deficient MEFs. On the other hand, in MEFs migrating towards a chemoattractant gradient, only peripheral ruffles (lamellipodia) are formed. In this migration, WAVE1-deficient MEFs still could form lamellipodia but WAVE2-deficient MEFs could not. All these data show that WAVE2 but not WAVE1 is essential for lamellipodium formation and directed migration.

Diagnosis of infectious mononucleosis caused by Epstein-Barr virus in infants.

PubMed

Dohno, Sumitaka; Maeda, Akihiko; Ishiura, Yoshihito; Sato, Tetsuya; Fujieda, Mikiya; Wakiguchi, Hiroshi

2010-08-01

The diagnosis of infectious mononucleosis (IM) is usually on serologic tests. The responses of anti-Epstein-Barr virus (anti-EBV) antibodies are weak in infants. The authors encountered some IM infants in whom anti-EBV antibodies were undetectable during early stage, although EBV genome was found in their blood. The aim of the present study was therefore to clarify the frequency of anti-EBV-antibody negative IM cases. The EBV serostatus of 104 IM children diagnosed on Sumaya criteria was retrospectively studied. The EBV genome in peripheral blood mononuclear cells was measured. The anti-viral capsid antigen-IgM (anti-VCA-IgM)-positive rate in the acute phase was only 25% in infants but 80% in patients ≥ 4 years of age. Twenty percent of the infants were negative for all anti-EBV antibodies and required repeated serologic tests. For infants, the significant rise in anti-VCA-IgG was the most sensitive marker. Three seronegative infants with IM symptoms, with circulating EBV genome during acute phase, were eventually considered as having IM on anti-VCA-IgG seroconversion thereafter. To diagnose IM in infants the serologic test alone in the acute phase is not sensitive enough. It is proposed that the EBV genome be evaluated in peripheral blood mononuclear cells when infants presenting with IM symptoms are negative for anti-EBV antibodies during the acute phase. © 2010 Japan Pediatric Society.

1. VIEW TO EAST, FRONT AND SIDE. Vanadium Corporation ...

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1. VIEW TO EAST, FRONT AND SIDE. - Vanadium Corporation of America (VCA) Naturita Mill, Mechanic Shed, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

2. VIEW TO WEST, REAR AND SIDE. Vanadium Corporation ...

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2. VIEW TO WEST, REAR AND SIDE. - Vanadium Corporation of America (VCA) Naturita Mill, Mechanic Shed, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

1. VIEW TO EAST, FRONT AND SIDE. Vanadium Corporation ...

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1. VIEW TO EAST, FRONT AND SIDE. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Variational Continuous Assimilation of TMI and SSM/I Rain Rates: Impact on GEOS-3 Hurricane Analyses and Forecasts

NASA Technical Reports Server (NTRS)

Hou, Arthur Y.; Zhang, Sara Q.; Reale, Oreste

2003-01-01

We describe a variational continuous assimilation (VCA) algorithm for assimilating tropical rainfall data using moisture and temperature tendency corrections as the control variable to offset model deficiencies. For rainfall assimilation, model errors are of special concern since model-predicted precipitation is based on parameterized moist physics, which can have substantial systematic errors. This study examines whether a VCA scheme using the forecast model as a weak constraint offers an effective pathway to precipitation assimilation. The particular scheme we exarnine employs a '1+1' dimension precipitation observation operator based on a 6-h integration of a column model of moist physics from the Goddard Earth Observing System (GEOS) global data assimilation system DAS). In earlier studies, we tested a simplified version of this scheme and obtained improved monthly-mean analyses and better short-range forecast skills. This paper describes the full implementation ofthe 1+1D VCA scheme using background and observation error statistics, and examines how it may improve GEOS analyses and forecasts of prominent tropical weather systems such as hurricanes. Parallel assimilation experiments with and without rainfall data for Hurricanes Bonnie and Floyd show that assimilating 6-h TMI and SSM/I surfice rain rates leads to more realistic storm features in the analysis, which, in turn, provide better initial conditions for 5-day storm track prediction and precipitation forecast. These results provide evidence that addressing model deficiencies in moisture tendency may be crucial to making effective use of precipitation information in data assimilation.

4. DETAIL OF GEARWELL AND GENERATOR, WEST VIEW. Vanadium ...

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4. DETAIL OF GEARWELL AND GENERATOR, WEST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

A novel mouse model of human prostate cancer to study intraprostatic tumor growth and the development of lymph node metastases.

PubMed

Linxweiler, Johannes; Körbel, Christina; Müller, Andreas; Hammer, Markus; Veith, Christian; Bohle, Rainer M; Stöckle, Michael; Junker, Kerstin; Menger, Michael D; Saar, Matthias

2018-06-01

In this study, we aimed to establish a versatile in vivo model of prostate cancer, which adequately mimics intraprostatic tumor growth, and the natural routes of metastatic spread. In addition, we analyzed the capability of high-resolution ultrasonography (hrUS), in vivo micro-CT (μCT), and 9.4T MRI to monitor tumor growth and the development of lymph node metastases. A total of 5 × 10 5 VCaP cells or 5 × 10 5 cells of LuCaP136- or LuCaP147 spheroids were injected into the prostate of male CB17-SCID mice (n = 8 for each cell type). During 12 weeks of follow-up, orthotopic tumor growth, and metastatic spread were monitored by repetitive serum-PSA measurements and imaging studies including hrUS, μCT, and 9.4T MRI. At autopsy, primary tumors and metastases were harvested and examined by histology and immunohistochemistry (CK5, CK8, AMACR, AR, Ki67, ERG, and PSA). From imaging results and PSA-measurements, tumor volume doubling time, tumor-specific growth rate, and PSA-density were calculated. All 24 mice developed orthotopic tumors. The tumor growth could be reliably monitored by a combination of hrUS, μCT, MRI, and serum-PSA measurements. In most animals, lymph node metastases could be detected after 12 weeks, which could also be well visualized by hrUS, and MRI. Immunohistochemistry showed positive signals for CK8, AMACR, and AR in all xenograft types. CK5 was negative in VCaP- and focally positive in LuCaP136- and LuCaP147-xenografts. ERG was positive in VCaP- and negative in LuCaP136- and LuCaP147-xenografts. Tumor volume doubling times and tumor-specific growth rates were 21.2 days and 3.9 %/day for VCaP-, 27.6 days and 3.1 %/day for LuCaP136- and 16.2 days and 4.5 %/day for LuCaP147-xenografts, respectively. PSA-densities were 433.9 ng/mL per milliliter tumor for VCaP-, 6.5 ng/mL per milliliter tumor for LuCaP136-, and 11.2 ng/mL per milliliter tumor for LuCaP147-xenografts. By using different monolayer and 3D spheroid cell cultures in an orthotopic xenograft model, we established an innovative, versatile in vivo model of prostate cancer, which enables the study of both intraprostatic tumor growth as well as metastatic spread to regional lymph nodes. HrUS and MRI are feasible tools to monitor tumor growth and the development of lymph node metastases while these cannot be visualized by μCT. © 2018 Wiley Periodicals, Inc.

[Investigation of Epstein-Barr virus and herpes simplex virus markers by serological and molecular methods in patients with rheumatoid arthritis and systemic lupus erythematosus].

PubMed

Us, Tercan; Cetin, Esin; Kaşifoğlu, Nilgün; Kaşifoğlu, Timuçin; Akgün, Yurdanur

2011-10-01

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) which are autoimmune diseases usually questioned for their association with many infectious agents have etiopathogenesis related to genetic, immunologic, hormonal and even environmental factors. The most commonly attributed etiologic agents are herpes group viruses. The aim of this study was to investigate the role of Epstein-Barr virus (EBV) and herpes simplex (HSV) viruses in the etiology of RA and SLE. A total of 137 patients (87 RA and 50 SLE; mean age: 33 ± 12 years) who were admitted to Eskisehir Osmangazi University Medical Faculty Rheumatology Department between January 2007-January 2008 and diagnosed according to 1987 ACR (American College of Rheumatology) criteria have been included in the study, together with 50 healthy blood donors (mean age: 35 ± 14 years) as control group. Serum samples obtained from all of the cases were tested for EBV VCA-IgG, VCA-IgM, EA/D-IgG and EBNA-IgG (Trinity Biotech, USA); IgM and IgG antibodies against HSV-1 and HSV-2 by ELISA method (Dia-Pro Diagnostic, Italy), and the presence of viral nucleic acids in blood samples were investigated by real-time quantitative polymerase chain reaction (RTPCR; Qiagen, USA). EBV VCA-IgM was negative in all of the RA, SLE and control group patients. VCA-IgG positivity were 98% and 96%, and for EBNA-IgG 98.5% and 100%, in patient and control groups, respectively. There was no statistically significant difference between the groups regarding VCA-IgG and EBNA- IgG positivity (p> 0.05). On the other hand, EBV EA/D-IgG positivity rate found in the SLE group (34%) was significantly higher than RA (7%) and control (12%) groups (p< 0.001 and p< 0.05, respectively). There was no significant difference between RA and control groups in terms of EA/D-IgG positivity (p> 0.05). Regarding herpes simplex virus serology, HSV1-IgG seropositivity were 99% and 94% and HSV2-IgG positivity were 8% and 12% in the patient and control groups, respectively. There was no statistically significant difference between the groups according to the positivity rates of IgM and IgG specific for HSV-1 and HSV-2 (p> 0.05). All of the cases were found negative in terms of EBV, HSV-1 and HSV- 2 DNAs according to double-checked RT-PCR results. In conclusion, no significant difference was determined for EBV and HSV serologic markers in RA and SLE patients compared to the control group. However, significantly higher rate of EBV EA/D-IgG positivity in SLE patients might have indicated a possible association between SLE and EBV infection. Larger scale, prospective studies including examination of the synovial fluid/tissue samples are required to enlighten the association between SLE and EBV.

2. DETAIL OF CONVEYOR BELT PATH AND CATWALK, NORTHEAST VIEW. ...

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2. DETAIL OF CONVEYOR BELT PATH AND CATWALK, NORTHEAST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

13. VIEW TO SOUTHEAST, BRICK SKINNER SALT ROASTER AND STEEL ...

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13. VIEW TO SOUTHEAST, BRICK SKINNER SALT ROASTER AND STEEL SKINNER SALT ROASTER. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

12. VIEW TO SOUTH, BRICK SKINNER SALT ROASTER AND STEEL ...

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12. VIEW TO SOUTH, BRICK SKINNER SALT ROASTER AND STEEL SKINNER SALT ROASTER. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

10. VIEW TO SOUTHEAST, SAMPLING BUILDING, FOUNDATION, WATER TOWER, AND ...

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10. VIEW TO SOUTHEAST, SAMPLING BUILDING, FOUNDATION, WATER TOWER, AND SKINNER SALT ROASTERS. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Intratumoral conversion of adrenal androgen precursors drives androgen receptor-activated cell growth in prostate cancer more potently than de novo steroidogenesis.

PubMed

Kumagai, Jinpei; Hofland, Johannes; Erkens-Schulze, Sigrun; Dits, Natasja F J; Steenbergen, Jacobie; Jenster, Guido; Homma, Yukio; de Jong, Frank H; van Weerden, Wytske M

2013-11-01

Despite an initial response to hormonal therapy, patients with advanced prostate cancer (PC) almost always progress to castration-resistant disease (CRPC). Although serum testosterone (T) is reduced by androgen deprivation therapy, intratumoral T levels in CRPC are comparable to those in prostate tissue of eugonadal men. These levels could originate from intratumoral conversion of adrenal androgens and/or from de novo steroid synthesis. However, the relative contribution of de novo steroidogenesis to AR-driven cell growth is unknown. The relative contribution of androgen biosynthetic pathways to activate androgen receptor (AR)-regulated cell growth and expression of PSA, FKBP5, and TMPRSS2 was studied at physiologically relevant levels of adrenal androgen precursors and intermediates of de novo androgen biosynthesis in human prostate cancer cell lines, PC346C, VCaP, and LNCaP. In PC346C and VCaP, responses to pregnenolone and progesterone were absent or minimal, while large effects of adrenal androgen precursors were found. VCaP CRPC clones overexpressing CYP17A1 did not acquire an increased ability to use pregnenolone or progesterone to activate AR. In contrast, all precursors stimulated growth and gene expression in LNCaP cells, presumably resulting from the mutated AR in these cells. Our data indicate that at physiological levels of T precursors PC cells can generally convert adrenal androgens, while de novo steroidogenesis is not generally possible in PC cells and is not able to support AR transactivation and PC growth. © 2013 Wiley Periodicals, Inc.

Epstein-Barr virus in multiple sclerosis.

PubMed

Abdelrahman, Hisham S; Selim, Heba S; Hashish, Mona H; Sultan, Lobna I

2014-08-01

Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system. Many diseases are associated with Epstein-Barr virus (EBV) infection, such as infectious mononucleosis and many types of malignancies, and it is thought to be related to some diseases of autoimmune origin, such as rheumatoid arthritis, systemic lupus erythematosis, and others. The present study aimed to assess EBV in patients with MS. This case-control study was conducted from October 2012 to September 2013 on 75 MS patients and non-MS controls. Both were tested quantitatively for immunoglobulin G (IgG) antibodies against Epstein-Barr nuclear antigen-1 (EBNA1) and viral capsid antigen (VCA) using the enzyme linked immunosorbent assay technique. Seventy MS patients (93.3%) were positive for EBNA1 IgG compared with 68 controls (90.7%). In MS patients, the mean EBNA1 IgG serum level was 310.91 (±131.05) U/ml; meanwhile, among controls the mean serum EBNA IgG level was 177.81 (±104.98) U/ml.All patients with MS were positive for VCA IgG, whereas only 60 (80.0%) controls were positive. In the MS group, the VCA IgG mean level was 302.19 (±152.11) U/ml compared with 167.94 (±111.79) U/ml in controls. The differences in the serum levels of both markers between the two groups were statistically significant (P<0.001). EBV proved to have a unique immunological pattern in MS patients when compared with non-MS controls. Further studies for more confirmation of the relation between EBV and MS on a large scale are recommended.

Enhancement of branching efficiency by the actin filament-binding activity of N-WASP/WAVE2.

PubMed

Suetsugu, S; Miki, H; Yamaguchi, H; Obinata, T; Takenawa, T

2001-12-01

The actin-related protein (Arp) 2/3 complex is an essential regulator of de novo actin filament formation. Arp2/3 nucleates the polymerization of actin and creates branched actin filaments when activated by Arp2/3-complex activating domain (VCA) of Wiskott-Aldrich syndrome proteins (WASP family proteins). We found that the branching of actin filaments on pre-existing ADP filaments mediated by the Arp2/3 complex is twice as efficient when Arp2/3 was activated by wild-type neural WASP (N-WASP) or WASP-family verprolin-homologous protein (WAVE) 2 than when activated by the VCA domain alone. By contrast, there was no difference between wild-type N-WASP or WAVE2 and VCA in the branching efficiency on de novo filaments, which are thought to consist mainly of ADP-phosphate filaments. This increased branching efficiency on ADP filaments is due to the basic region located in the center of N-WASP and WAVE2, which was found to associate with ADP actin filaments. Actin filaments and phosphatidylinositol bisphosphate (PIP2) associate with N-WASP at different sites. This association of N-WASP and WAVE2 with actin filaments enhanced recruitment of Arp2/3 to the pre-existing filaments, presumably leading to efficient nucleation and branch formation on pre-existing filaments. These data together suggest that the actin filament binding activity of N-WASP and WAVE2 in the basic region increases the number of barbed ends created on pre-existing filaments. Efficient branching on ADP filaments may be important for initiation of actin-based motility.

6. VIEW TO WEST, SAMPLING BUILDING, MECHANIC SHED, MILL WAREHOUSE, ...

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6. VIEW TO WEST, SAMPLING BUILDING, MECHANIC SHED, MILL WAREHOUSE, DRYERS, AND GRINDING/ROD MILL. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

8. VIEW TO SOUTHEAST, DRYERS, GRINDING/ROD MILL, MECHANIC SHED, AND ...

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8. VIEW TO SOUTHEAST, DRYERS, GRINDING/ROD MILL, MECHANIC SHED, AND SKINNER SALT ROASTERS. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

3. VIEW TO NORTHEAST, MECHANIC SHED, DRYERS, GRINDING/ROD MILL, AND ...

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3. VIEW TO NORTHEAST, MECHANIC SHED, DRYERS, GRINDING/ROD MILL, AND SKINNER SALT ROASTERS. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

7. VIEW TO EAST, MILL WAREHOUSE, DRYERS, GRINDING/ROD MILL, AND ...

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7. VIEW TO EAST, MILL WAREHOUSE, DRYERS, GRINDING/ROD MILL, AND MECHANIC SHED. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

5. DETAIL OF ROD MILL BASE AND CONVEYOR BELT SUPPORT, ...

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5. DETAIL OF ROD MILL BASE AND CONVEYOR BELT SUPPORT, EAST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

4. VIEW TO NORTHEAST, SKINNER SALT ROASTERS, SAMPLING BUILDING, WATER ...

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4. VIEW TO NORTHEAST, SKINNER SALT ROASTERS, SAMPLING BUILDING, WATER TOWER, AND OFFICE BUILDING. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Preventing Rejection

MedlinePlus

... living donor Being a living donor Liver Heart Lung Pancreas Intestine VCA Common diseases Living with devices Before Before the transplant How ... At least one episode of acute rejection is common within the first year ... after transplantation. Therefore, organ recipients should be aware of the ...

Performance of the architect EBV antibody panel for determination of Epstein-Barr virus infection stage in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis.

PubMed

Guerrero-Ramos, Alvaro; Patel, Mauli; Kadakia, Kinjal; Haque, Tanzina

2014-06-01

The Architect EBV antibody panel is a new chemiluminescence immunoassay system used to determine the stage of Epstein-Barr virus (EBV) infection based on the detection of IgM and IgG antibodies to viral capsid antigen (VCA) and IgG antibodies against Epstein-Barr nuclear antigen 1 (EBNA-1). We evaluated its diagnostic accuracy in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis (IM) using the RecomLine EBV IgM and IgG immunoblots as the reference standard. In addition, the use of the antibody panel in a sequential testing algorithm based on initial EBNA-1 IgG analysis was assessed for cost-effectiveness. Finally, we investigated the degree of cross-reactivity of the VCA IgM marker during other primary viral infections that may present with an EBV IM-like picture. High sensitivity (98.3% [95% confidence interval {CI}, 90.7 to 99.7%]) and specificity (94.2% [95% CI, 87.9 to 97.8%]) were found after testing 162 precharacterized archived serum samples. There was perfect agreement between the use of the antibody panel in sequential and parallel testing algorithms, but substantial cost savings (23%) were obtained with the sequential strategy. A high rate of reactive VCA IgM results was found in primary cytomegalovirus (CMV) infections (60.7%). In summary, the Architect EBV antibody panel performs satisfactorily in the investigation of EBV IM in immunocompetent adolescents and young adults, and the application of an EBNA-1 IgG-based sequential testing algorithm is cost-effective in this diagnostic setting. Concomitant testing for CMV is strongly recommended to aid in the interpretation of EBV serological patterns. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Enzalutamide and CXCR7 inhibitor combination treatment suppresses cell growth and angiogenic signaling in castration‐resistant prostate cancer models

PubMed Central

Luo, Yong; Azad, Abul Kalam; Karanika, Styliani; Basourakos, Spyridon P.; Zuo, Xuemei; Wang, Jianxiang; Yang, Luan; Yang, Guang; Korentzelos, Dimitrios; Yin, Jianhua; Park, Sanghee; Zhang, Penglie; Campbell, James J.; Schall, Thomas J.; Cao, Guangwen; Li, Likun

2018-01-01

Previous studies have shown that increased levels of chemokine receptor CXCR7 are associated with the increased invasiveness of prostate cancer cells. We now show that CXCR7 expression is upregulated in VCaP and C4‐2B cells after enzalutamide (ENZ) treatment. ENZ treatment induced apoptosis (sub‐G1) in VCaP and C4‐2B cells, and this effect was further increased after combination treatment with ENZ and CCX771, a specific CXCR7 inhibitor. The levels of p‐EGFR (Y1068), p‐AKT (T308) and VEGFR2 were reduced after ENZ and CCX771 combination treatment compared to single agent treatment. In addition, significantly greater reductions in migration were shown after combination treatment compared to those of single agents or vehicle controls, and importantly, similar reductions in the levels of secreted VEGF were also demonstrated. Orthotopic VCaP xenograft growth and subcutaneous MDA133‐4 patient‐derived xenograft (PDX) tumor growth was reduced by single agent treatment, but significantly greater suppression was observed in the combination treatment group. Although overall microvessel densities in the tumor tissues were not different among the different treatment groups, a significant reduction in large blood vessels (>100 μm2) was observed in tumors following combination treatment. Apoptotic indices in tumor tissues were significantly increased following combination treatment compared with vehicle control‐treated tumor tissues. Our results demonstrate that significant tumor suppression mediated by ENZ and CXCR7 combination treatment may be due, in part, to reductions in proangiogenic signaling and in the formation of large blood vessels in prostate cancer tumors. PMID:29277895

Celastrol suppresses tumor cell growth through targeting an AR-ERG-NF-κB pathway in TMPRSS2/ERG fusion gene expressing prostate cancer.

PubMed

Shao, Longjiang; Zhou, Zhansong; Cai, Yi; Castro, Patricia; Dakhov, Olga; Shi, Ping; Bai, Yaoxia; Ji, Huixiang; Shen, Wenhao; Wang, Jianghua

2013-01-01

The TMPRSS2/ERG (T/E) fusion gene is present in the majority of all prostate cancers (PCa). We have shown previously that NF-kB signaling is highly activated in these T/E fusion expressing cells via phosphorylation of NF-kB p65 Ser536 (p536). We therefore hypothesize that targeting NF-kB signaling may be an efficacious approach for the subgroup of PCas that carry T/E fusions. Celastrol is a well known NF-kB inhibitor, and thus may inhibit T/E fusion expressing PCa cell growth. We therefore evaluated Celastrol's effects in vitro and in vivo in VCaP cells, which express the T/E fusion gene. VCaP cells were treated with different concentrations of Celastrol and growth inhibition and target expression were evaluated. To test its ability to inhibit growth in vivo, 0.5 mg/kg Celastrol was used to treat mice bearing subcutaneous VCaP xenograft tumors. Our results show Celastrol can significantly inhibit the growth of T/E fusion expressing PCa cells both in vitro and in vivo through targeting three critical signaling pathways: AR, ERG and NF-kB in these cells. When mice received 0.5 mg/kg Celastrol for 4 times/week, significant growth inhibition was seen with no obvious toxicity or significant weight loss. Therefore, Celastrol is a promising candidate drug for T/E fusion expressing PCa. Our findings provide a novel strategy for the targeted therapy which may benefit the more than half of PCa patients who have T/E fusion expressing PCas.

Defective activity of Epstein-Barr virus (EBV) specific cytotoxic T lymphocytes in children with chronic active EBV infection and in their parents.

PubMed

Fujieda, M; Wakiguchi, H; Hisakawa, H; Kubota, H; Kurashige, T

1993-10-01

Antibodies of Epstein-Barr virus (EBV), EBV-specific cytotoxic T lymphocyte (EBVCTL) activity and the lymphocyte subset of CTL were examined in 13 Japanese children with chronic active EBV infection (CAEBV) and their parents (eight fathers and 10 mothers). Anti-virus-capsid antigen (VCA)-IgG antibody titers ranged from 1:640 to 1:5120 in the patients with CAEBV and from 1:40 to 1:640 in the parents. While anti-VCA-IgM antibody was detected in three patients, anti-VCA-IgA antibody in five and anti-early-antigen (EA)-IgG antibody in 11, no antibody was detected in the parents except anti-EA antibody, which was positive in the mothers of cases 5 and 13 (1:10 and 1:40). Anti-EBV-associated nuclear antigen (EBNA) antibody was < or = 1:10 in six out of 13 patients with CAEBV and in 10 out of 18 parents tested. Epstein-Barr virus activity was significantly lower (P < 0.005) both in the children with CAEBV and in their parents than in seropositive age-matched controls. Proportions of a CTL subset (CD8+ CD11- lymphocytes) in the patients with CAEBV were significantly higher (P < 0.005) than in controls, while those in the parents were at the same level as in controls. Defective EBVCTL activity and anti-EBNA-antibody responses were frequently observed both in children with CAEBV and in their parents, which may suggest that the abnormal immune response to EBV may be based on a familial disorder, though no familial involvement has been reported in Japanese children with CAEBV.

Performance of the Architect EBV Antibody Panel for Determination of Epstein-Barr Virus Infection Stage in Immunocompetent Adolescents and Young Adults with Clinical Suspicion of Infectious Mononucleosis

PubMed Central

Patel, Mauli; Kadakia, Kinjal; Haque, Tanzina

2014-01-01

The Architect EBV antibody panel is a new chemiluminescence immunoassay system used to determine the stage of Epstein-Barr virus (EBV) infection based on the detection of IgM and IgG antibodies to viral capsid antigen (VCA) and IgG antibodies against Epstein-Barr nuclear antigen 1 (EBNA-1). We evaluated its diagnostic accuracy in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis (IM) using the RecomLine EBV IgM and IgG immunoblots as the reference standard. In addition, the use of the antibody panel in a sequential testing algorithm based on initial EBNA-1 IgG analysis was assessed for cost-effectiveness. Finally, we investigated the degree of cross-reactivity of the VCA IgM marker during other primary viral infections that may present with an EBV IM-like picture. High sensitivity (98.3% [95% confidence interval {CI}, 90.7 to 99.7%]) and specificity (94.2% [95% CI, 87.9 to 97.8%]) were found after testing 162 precharacterized archived serum samples. There was perfect agreement between the use of the antibody panel in sequential and parallel testing algorithms, but substantial cost savings (23%) were obtained with the sequential strategy. A high rate of reactive VCA IgM results was found in primary cytomegalovirus (CMV) infections (60.7%). In summary, the Architect EBV antibody panel performs satisfactorily in the investigation of EBV IM in immunocompetent adolescents and young adults, and the application of an EBNA-1 IgG-based sequential testing algorithm is cost-effective in this diagnostic setting. Concomitant testing for CMV is strongly recommended to aid in the interpretation of EBV serological patterns. PMID:24695777

The antiandrogenic effect of finasteride against a mutant androgen receptor

PubMed Central

Chhipa, Rishi Raj; Zhang, Haitao; Ip, Clement

2011-01-01

Finasteride is known to inhibit Type 2 5α-reductase and thus block the conversion of testosterone to dihydrotestosterone (DHT). The structural similarity of finasteride to DHT raises the possibility that finasteride may also interfere with the function of the androgen receptor (AR). Experiments were carried out to evaluate the antiandrogenic effect of finasteride in LNCaP, C4-2 and VCaP human prostate cancer cells. Finasteride decreased DHT binding to AR, and DHT-stimulated AR activity and cell growth in LNCaP and C4-2 cells, but not in VCaP cells. LNCaP and C4-2 (derived from castration-resistant LNCaP) cells express the T877A mutant AR, while VCaP cells express the wild-type AR. When PC-3 cells, which are AR-null, were transfected with either the wild-type or the T877A mutant AR, only the mutant AR-expressing cells were sensitive to finasteride inhibition of DHT binding. Peroxiredoxin-1 (Prx1) is a novel endogenous facilitator of AR binding to DHT. In Prx1-rich LNCaP cells, the combination of Prx1 knockdown and finasteride was found to produce a greater inhibitory effect on AR activity and cell growth than either treatment alone. The observation suggests that cells with a low expression of Prx1 are likely to be more responsive to the antiandrogenic effect of finasteride. Additional studies showed that the efficacy of finasteride was comparable to that of bicalutamide (a widely used non-steroidal antiandrogen). The implication of the above findings is discussed in the context of developing strategies to improve the outcome of androgen deprivation therapy. PMID:21386657

9. VIEW TO SOUTHSOUTHWEST, MINE WAREHOUSE, LABORATORY AND GRINDING/ROD MILL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. VIEW TO SOUTH-SOUTHWEST, MINE WAREHOUSE, LABORATORY AND GRINDING/ROD MILL (FOREGROUND), AND SAMPLING BUILDING AND WATER TOWER (BACKGROUND). - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Comparison of Abbott Architect®, Siemens Immulite®, and Diasorin Liaison® for determination of Epstein-Barr virus serological diagnosis.

PubMed

François, Catherine; Segard, Christine; Bouvier, Maryline; Stefanski, Martine; Pannier, Christine; Zawadzki, Patricia; Roussel, Catherine; Hecquet, Denise; Duverlie, Gilles; Brochot, Etienne; Castelain, Sandrine

2018-02-01

This study compared the performance of 3 automated immunoassays, Architect ® (Abbott), Immulite ® (Siemens) and Liaison ® (Diasorin), for Epstein-Barr virus (EBV) serology. Ninety-one serum samples collected in Amiens University Hospital were analyzed for the presence of Viral Capsid Antigen (VCA) IgG and IgM and Epstein-Barr Nuclear Antigen (EBNA) IgG. The agreement between the 3 assays was calculated for each marker individually and for determination of the EBV profile, based on interpretation of the combination of these 3 EBV markers. Although similar results were obtained with Architect ® and Liaison ® , several discordant results were observed with Immulite ® , particularly for EBNA IgG. A large number of EBNA IgG-positive results were observed, which interfered with interpretation of the EBV profile. In contrast, Immulite ® performed similarly to the 2 other assays for detection of VCA IgM. Copyright © 2017 Elsevier Inc. All rights reserved.

[Case of infectious mononucleosis with suspected primary coinfection with Chlamydophila (Chlamydia) pneumoniae and Epstein-Barr virus].

PubMed

Shizuma, Toru

2008-09-01

A 26-year-old male was hospitalized with fever and pharyngeal pain. Liver dysfunction and an increase in the percentage of atypical lymphocytes in the peripheral blood were detected. Computed tomography showed pneumonia involving the right lung and synpneumonic pleural effusion. Serum immunological tests showed positive results for Epstein-Barr virus (EBV) viral capsid antigen (VCA) IgM and IgG antibodies and Chlamydophila (Chlamydia) pneumoniae (C. pneumoniae) IgM and IgA antibodies on admission. The pneumonia and pleural effusion were no longer detectable after a week of treatment with starting azithromycin. At 7 weeks after admission, the liver function test results returned to within normal limits, the serum became negative for EBV VCA IgM antibody, the C. pneumoniae IgM antibody titer decreased, and the C. pneumoniae IgA and IgG antibody titers increased. This case was suspected to have infectious mononucleosis caused by primary coinfection with C. pneumoniae and EBV.

11. VIEW TO NORTH, STEELSKINNER SALT ROASTER AND BRICK SKINNER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. VIEW TO NORTH, STEEL-SKINNER SALT ROASTER AND BRICK SKINNER SALT ROASTER (FOREGROUND), AND MECHANIC SHED, MILL WAREHOUSE AND DRYERS (BACKGROUND). - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

Linear unmixing of multidate hyperspectral imagery for crop yield estimation

USDA-ARS?s Scientific Manuscript database

In this paper, we have evaluated an unsupervised unmixing approach, vertex component analysis (VCA), for the application of crop yield estimation. The results show that abundance maps of the vegetation extracted by the approach are strongly correlated to the yield data (the correlation coefficients ...

Invariant patterns in crystal lattices: Implications for protein folding algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

HART,WILLIAM E.; ISTRAIL,SORIN

2000-06-01

Crystal lattices are infinite periodic graphs that occur naturally in a variety of geometries and which are of fundamental importance in polymer science. Discrete models of protein folding use crystal lattices to define the space of protein conformations. Because various crystal lattices provide discretizations of the same physical phenomenon, it is reasonable to expect that there will exist invariants across lattices related to fundamental properties of the protein folding process. This paper considers whether performance-guaranteed approximability is such an invariant for HP lattice models. The authors define a master approximation algorithm that has provable performance guarantees provided that a specificmore » sublattice exists within a given lattice. They describe a broad class of crystal lattices that are approximable, which further suggests that approximability is a general property of HP lattice models.« less

Raman spectroscopic imaging as complementary tool for histopathologic assessment of brain tumors

NASA Astrophysics Data System (ADS)

Krafft, Christoph; Bergner, Norbert; Romeike, Bernd; Reichart, Rupert; Kalff, Rolf; Geiger, Kathrin; Kirsch, Matthias; Schackert, Gabriele; Popp, Jürgen

2012-02-01

Raman spectroscopy enables label-free assessment of brain tissues and tumors based on their biochemical composition. Combination of the Raman spectra with the lateral information allows grading of tumors, determining the primary tumor of brain metastases and delineating tumor margins - even during surgery after coupling with fiber optic probes. This contribution presents exemplary Raman spectra and images collected from low grade and high grade regions of astrocytic gliomas and brain metastases. A region of interest in dried tissue sections encompassed slightly increased cell density. Spectral unmixing by vertex component analysis (VCA) and N-FINDR resolved cell nuclei in score plots and revealed the spectral contributions of nucleic acids, cholesterol, cholesterol ester and proteins in endmember signatures. The results correlated with the histopathological analysis after staining the specimens by hematoxylin and eosin. For a region of interest in non-dried, buffer immersed tissue sections image processing was not affected by drying artifacts such as denaturation of biomolecules and crystallization of cholesterol. Consequently, the results correspond better to in vivo situations. Raman spectroscopic imaging of a brain metastases from renal cell carcinoma showed an endmember with spectral contributions of glycogen which can be considered as a marker for this primary tumor.

Determination of the Temperature Dependence of Heat Capacity for Some Molecular Crystals of Nitro Compounds

NASA Astrophysics Data System (ADS)

Kovalev, Yu. M.; Kuropatenko, V. F.

2018-05-01

An analysis of the existing approximations used for describing the dependence of heat capacity at a constant volume on the temperature of a molecular crystal has been carried out. It is shown that the considered Debye and Einstein approximations do not enable one to adequately describe the dependence of heat capacity at a constant volume on the temperature of the molecular crystals of nitro compounds. This inference requires the development of special approximations that would describe both low-frequency and high-frequency parts of the vibrational spectra of molecular crystals. This work presents a universal dependence allowing one to describe the dependence of heat capacity at a constant volume on temperature for a number of molecular crystals of nitro compounds.

Citrate, not phosphate, can dissolve calcium oxalate monohydrate crystals and detach these crystals from renal tubular cells.

PubMed

Chutipongtanate, Somchai; Chaiyarit, Sakdithep; Thongboonkerd, Visith

2012-08-15

Dissolution therapy of calcium oxalate monohydrate (COM) kidney stone disease has not yet been implemented due to a lack of well characterized COM dissolution agents. The present study therefore aimed to identify potential COM crystal dissolution compounds. COM crystals were treated with deionized water (negative control), 5 mM EDTA (positive control), 5 mM sodium citrate, or 5mM sodium phosphate. COM crystal dissolution activities of these compounds were evaluated by phase-contrast and video-assisted microscopic examinations, semi-quantitative analysis of crystal size, number and total mass, and spectrophotometric oxalate-dissolution assay. In addition, effects of these compounds on detachment of COM crystals, which adhered tightly onto renal tubular cell surface, were also investigated. The results showed that citrate, not phosphate, had a significant dissolution effect on COM crystals as demonstrated by significant reduction of crystal size (approximately 37% decrease), crystal number (approximately 53% decrease) and total crystal mass (approximately 72% decrease) compared to blank and negative controls. Spectrophotometric oxalate-dissolution assay successfully confirmed the COM crystal dissolution property of citrate. Moreover, citrate could detach up to 85% of the adherent COM crystals from renal tubular cell surface. These data indicate that citrate is better than phosphate for dissolution and detachment of COM crystals. Copyright © 2012 Elsevier B.V. All rights reserved.

Infectious mononucleosis accompanied by clonal proliferation of EBV-infected cells and infection of CD8-positive cells.

PubMed

Arai, Ayako; Yamaguchi, Takeshi; Komatsu, Honami; Imadome, Ken-Ichi; Kurata, Morito; Nagata, Kaoru; Miura, Osamu

2014-01-01

A 22-year-old male was admitted for a sustained fever of 2 months, lymphadenopathy, and liver dysfunction. Anti-VCA-IgM antibody was positive, with elevated Epstein-Barr virus (EBV)-DNA load in the peripheral blood. Liver biopsy revealed infiltration of CD8-positive and EBV-positive cells. Most peripheral blood mononuclear cells (PBMCs) were also positive for CD8, and showed detectable levels of EBV-DNA. Monoclonal proliferation of EBV-infected cells was detected in the PBMCs by Southern blotting for EBV-terminal repeat (EBV-TR). Although EBV-positive T-cell lymphoproliferative disease (EBV-T-LPD) was suspected, the symptoms spontaneously resolved within 12 months. Anti-VCA-IgM antibody and the clonal band of EBV-TR were negative 1 year after the onset, while anti-EBNA antibody was positive. The final diagnosis was thus confirmed as infectious mononucleosis (IM). Our results indicate that EBV-infected CD8-positive cells and clonal proliferation of EBV-infected cells may be temporally detected in IM. EBV-T-LPDs should be carefully excluded in such cases.

Atomic density functional and diagram of structures in the phase field crystal model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ankudinov, V. E., E-mail: vladimir@ankudinov.org; Galenko, P. K.; Kropotin, N. V.

2016-02-15

The phase field crystal model provides a continual description of the atomic density over the diffusion time of reactions. We consider a homogeneous structure (liquid) and a perfect periodic crystal, which are constructed from the one-mode approximation of the phase field crystal model. A diagram of 2D structures is constructed from the analytic solutions of the model using atomic density functionals. The diagram predicts equilibrium atomic configurations for transitions from the metastable state and includes the domains of existence of homogeneous, triangular, and striped structures corresponding to a liquid, a body-centered cubic crystal, and a longitudinal cross section of cylindricalmore » tubes. The method developed here is employed for constructing the diagram for the homogeneous liquid phase and the body-centered iron lattice. The expression for the free energy is derived analytically from density functional theory. The specific features of approximating the phase field crystal model are compared with the approximations and conclusions of the weak crystallization and 2D melting theories.« less

Variational Assimilation of Global Microwave Rainfall Retrievals: Physical and Dynamical Impact on GEOS Analyses and Forecasts

NASA Technical Reports Server (NTRS)

Lin, Xin; Zhang, Sara Q.; Hou, Arthur Y.

2006-01-01

Global microwave rainfall retrievals from a 5-satellite constellation, including TMI from TRMM, SSWI from DMSP F13, F14 and F15, and AMSR-E from EOS-AQUA, are assimilated into the NASA Goddard Earth Observing System (GEOS) Data Assimilation System (DAS) using a 1-D variational continuous assimilation (VCA) algorithm. The physical and dynamical impact of rainfall assimilation on GEOS analyses and forecasts is examined at various temporal and spatial scales. This study demonstrates that the 1-D VCA algorithm, which was originally developed and evaluated for rainfall assimilations over tropical oceans, can effectively assimilate satellite microwave rainfall retrievals and improve GEOS analyses over both the Tropics and the extratropics where the atmospheric processes are dominated by different large-scale dynamics and moist physics, and also over the land, where rainfall estimates from passive microwave radiometers are believed to be less accurate. Results show that rainfall assimilation renders the GEOS analysis physically and dynamically more consistent with the observed precipitation at the monthly-mean and 6-hour time scales. Over regions where the model precipitation tends to misbehave in distinctly different rainy regimes, the 1-D VCA algorithm, by compensating for errors in the model s moist time-tendency in a 6-h analysis window, is able to bring the rainfall analysis closer to the observed. The radiation and cloud fields also tend to be in better agreement with independent satellite observations in the rainfall-assimilation m especially over regions where rainfall analyses indicate large improvements. Assimilation experiments with and without rainfall data for a midlatitude frontal system clearly indicates that the GEOS analysis is improved through changes in the thermodynamic and dynamic fields that respond to the rainfall assimilation. The synoptic structures of temperature, moisture, winds, divergence, and vertical motion, as well as vorticity are more realistically captured across the front. Short-term forecasts using initial conditions assimilated with rainfall data also show slight improvements. 1

Vertebral coplanar alignment: a standardized technique for three dimensional correction in scoliosis surgery: technical description and preliminary results in Lenke type 1 curves.

PubMed

Vallespir, Gabriel Pizà; Flores, Jesús Burgos; Trigueros, Ignacio Sanpera; Sierra, Eduardo Hevia; Fernández, Pedro Doménech; Olaverri, Juan Carlos Rodríguez; Alonso, Manuel García; Galea, Rafael Ramos; Francisco, Antonio Pérez; Rodríguez de Paz, Beatriz; Carbonell, Pedro Gutiérrez; Thomas, Javier Vicente; López, José Luís González; Paulino, José Ignacio Maruenda; Pitarque, Carlos Barrios; García, Oscar Riquelme

2008-06-15

Prospective multicentric study. To present the preliminary results of an innovative method for standardized correction of scoliosis, vertebral coplanar alignment (VCA), based on a novel concept: the relocation of vertebral axis in a single plane. Normal standing spine has no rotation in coronal or transverse planes, therefore X and Z axis of vertebrae are in the same plane: they are coplanar. VCA intends to relocate these axis in one plane, correcting rotation and translation, while X axis are returned to its normal posterior divergence in sagittal plane in thoracic spine. Twenty-five consecutive adolescent idiopathic scoliosis patients (Lenke type 1) underwent posterior surgery with segmental pedicle screw fixation. Slotted tubes were attached to convex side screws. Two longitudinal rods were inserted through the end of tubes. Then, they were separated along the slots, driving the tubes into one plane, making the axis of the vertebrae coplanar and thus correcting transverse rotation and coronal translation. To obtain kyphosis, distal ends of the tubes were spread in thoracic spine. Correction was maintained by locking a definitive rod in the concave side, then tubes were retrieved and the convex side rod, inserted and tightened. Correction was assessed on preoperative and postoperative full-spine standing radiograph. Vertebral rotation was measured on computed tomography-scan and magnetic resonance imaging. Preoperative average thoracic curves of 61 degrees were corrected to 16 degrees (73%). Preoperative average thoracolumbar curves of 39 degrees were corrected to 12 degrees (70%). Preoperative average thoracic apical rotation of 24 degrees was corrected to 11 degrees (56%). Preoperative average thoracic kyphosis of 18 degrees remained unchanged after surgery; however, no patients had kyphosis <10 degrees after surgery. Rib hump improved from 30 to 11 mm (65%). There were no perioperative complications. VCA provided excellent correction of coronal and transverse planes with normalization of thoracic kyphosis in Lenke type 1 adolescent idiopathic scoliosis surgery.

Early Virological and Immunological Events in Asymptomatic Epstein-Barr Virus Infection in African Children

PubMed Central

Jayasooriya, Shamanthi; de Silva, Thushan I.; Njie-jobe, Jainaba; Sanyang, Chilel; Leese, Alison M.; Bell, Andrew I.; McAulay, Karen A.; Yanchun, Peng; Long, Heather M.; Dong, Tao; Whittle, Hilton C.; Rickinson, Alan B.; Rowland-Jones, Sarah L.; Hislop, Andrew D.; Flanagan, Katie L.

2015-01-01

Epstein-Barr virus (EBV) infection often occurs in early childhood and is asymptomatic. However, if delayed until adolescence, primary infection may manifest as acute infectious mononucleosis (AIM), a febrile illness characterised by global CD8+ T-cell lymphocytosis, much of it reflecting a huge expansion of activated EBV-specific CD8+ T-cells. While the events of AIM have been intensely studied, little is known about how these relate to asymptomatic primary infection. Here Gambian children (14–18 months old, an age at which many acquire the virus) were followed for the ensuing six months, monitoring circulating EBV loads, antibody status against virus capsid antigen (VCA) and both total and virus-specific CD8+ T-cell numbers. Many children were IgG anti-VCA-positive and, though no longer IgM-positive, still retained high virus loads comparable to AIM patients and had detectable EBV-specific T-cells, some still expressing activation markers. Virus loads and the frequency/activation status of specific T-cells decreased over time, consistent with resolution of a relatively recent primary infection. Six children with similarly high EBV loads were IgM anti-VCA-positive, indicating very recent infection. In three of these donors with HLA types allowing MHC-tetramer analysis, highly activated EBV-specific T-cells were detectable in the blood with one individual epitope response reaching 15% of all CD8+ T-cells. That response was culled and the cells lost activation markers over time, just as seen in AIM. However, unlike AIM, these events occurred without marked expansion of total CD8+ numbers. Thus asymptomatic EBV infection in children elicits a virus-specific CD8+ T-cell response that can control the infection without over-expansion; conversely, in AIM it appears the CD8 over-expansion, rather than virus load per se, is the cause of disease symptoms. PMID:25816224

Seroepizootiology of the herpesvirus Papio (HVP) infection in healthy baboons (Papio hamadryas) of high- and low-lymphoma risk populations.

PubMed

Voevodin, A F; Ponomarjeva, T I; Lapin, B A

1985-01-01

Seroepizootiology of Herpesvirus Papio (HVP) infection was studied in three groups of healthy hamadryas baboons (Papio hamadryas): the main Sukhumi (high-lymphoma) stock, forest Sukhumi (lymphoma-free) stock and newly imported wild animals. The prevalence to HVP infection, as judged by anti-VCA-HVP positivity, was approximately the same in both Sukhumi stocks (86% and 90% respectively) and it was significantly lower in the pooled group of newly imported baboons. It is interesting that prevalence of HVP infection in the different independent groups varied markedly (35-79%). Geometric mean titers of positives in all groups were approximately the same. The prevalence of HVP infection was age-dependent. It increased during the first years of life reaching the maximum (about 100%) at the age of 5 years being stable up to the age of 18 years and "decreased" at very old ages (over 18 years). The prevalence of HVP infection in newly imported baboons increased with age up to 71% in a group of the "oldest" monkeys and did not plateau. No significant sex differences in anti-HVP titers were found. Anti-EA-HVP-positive (with one exception) and anti-HUPNA-positive animals were found only in the main Sukhumi stock. Thus, "serologic activity" against HVP infection was the highest in the ligh-lymphoma stock.

A landscape scale valley confinement algorithm: Delineating unconfined valley bottoms for geomorphic, aquatic, and riparian applications

Treesearch

David E. Nagel; John M. Buffington; Sharon L. Parkes; Seth Wenger; Jaime R. Goode

2014-01-01

Valley confinement is an important landscape characteristic linked to aquatic habitat, riparian diversity, and geomorphic processes. This report describes a GIS program called the Valley Confinement Algorithm (VCA), which identifies unconfined valleys in montane landscapes. The algorithm uses nationally available digital elevation models (DEMs) at 10-30 m resolution to...

Positioning Bascularized Composite Allotransplantation with the Spectrum of Transplantion

DTIC Science & Technology

2015-10-01

therapeutic option for patients in need of advanced tissue reconstruction. II. Keywords Biorepository, vascularized composite allograft , nonhuman primates... tissues (e.g. hand, face) into a useful therapeutic option for individuals in need of advance tissue reconstruction and replacement. The proposal...death but increased the rate of soft tissue injury. Vascularized composite allotransplantation (VCA) has recently emerged as a promising strategy for

Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival

DTIC Science & Technology

2016-10-01

AWARD NUMBER: W81XWH-15-1-0244 TITLE: Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival...2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival...observed effects these particles have on allograft survival. Key Words CTA Composite Tissue Allotransplantation VCA Vascularized Composite

Targeting Sulfotransferase (SULT) 2B1b as a Regulator of Cholesterol Metabolism in Prostate Cancer

DTIC Science & Technology

2015-10-01

Roswell Park shared resource to arrange for sample analysis. Determine requirements for analysis: Completed, several samples of LNCaP with siRNA-based...SULT2b1knocked down greater than 80% were submitted to The Roswell park shared resource for lipid analysis Cell lines used: wt  LNCaP,  VCaP

Stress-induced reactivation of Epstein-Barr virus in astronauts

NASA Technical Reports Server (NTRS)

Stowe, R. P.; Pierson, D. L.; Feeback, D. L.; Barrett, A. D.

2000-01-01

Herpesviruses are leading causes of infectious blindness and death in immunocompromised individuals. Impaired cellular immunity, which is known to result in increased frequency and severity of herpesvirus infections, has been demonstrated both during and after spaceflight. Therefore, we examined whether Epstein-Barr virus (EBV), a well-characterized latent herpesvirus, undergoes reactivation in astronauts. Sera from Shuttle astronauts, taken before and after spaceflight, were examined for evidence of EBV reactivation. The geometric mean antibody titer to EBV viral capsid antigen (VCA) was significantly increased prior to flight compared to baseline (p = 0. 0001). After spaceflight, evidence of acute lytic replication was found in which 8- to 64-fold increases in EBV early antigen (EA) antibodies occurred without significant increases in antibodies to measles virus. Additionally, stress-induced shifts in circulating leukocytes and elevated levels of urinary cortisol and epinephrine were found. Overall, significant increases in EA or high VCA/EA antibody titers were found in 8 of 23 (35%) male astronauts and 3 of 5 (60%) female astronauts. These results indicate that stress reactivates EBV prior to flight and suggest that acute lytic replication of EBV occurs during spaceflight. Copyright 2000 S. Karger AG, Basel.

A foreground object features-based stereoscopic image visual comfort assessment model

NASA Astrophysics Data System (ADS)

Jin, Xin; Jiang, G.; Ying, H.; Yu, M.; Ding, S.; Peng, Z.; Shao, F.

2014-11-01

Since stereoscopic images provide observers with both realistic and discomfort viewing experience, it is necessary to investigate the determinants of visual discomfort. By considering that foreground object draws most attention when human observing stereoscopic images. This paper proposes a new foreground object based visual comfort assessment (VCA) metric. In the first place, a suitable segmentation method is applied to disparity map and then the foreground object is ascertained as the one having the biggest average disparity. In the second place, three visual features being average disparity, average width and spatial complexity of foreground object are computed from the perspective of visual attention. Nevertheless, object's width and complexity do not consistently influence the perception of visual comfort in comparison with disparity. In accordance with this psychological phenomenon, we divide the whole images into four categories on the basis of different disparity and width, and exert four different models to more precisely predict its visual comfort in the third place. Experimental results show that the proposed VCA metric outperformance other existing metrics and can achieve a high consistency between objective and subjective visual comfort scores. The Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are over 0.84 and 0.82, respectively.

Estimating the biophysical properties of neurons with intracellular calcium dynamics.

PubMed

Ye, Jingxin; Rozdeba, Paul J; Morone, Uriel I; Daou, Arij; Abarbanel, Henry D I

2014-06-01

We investigate the dynamics of a conductance-based neuron model coupled to a model of intracellular calcium uptake and release by the endoplasmic reticulum. The intracellular calcium dynamics occur on a time scale that is orders of magnitude slower than voltage spiking behavior. Coupling these mechanisms sets the stage for the appearance of chaotic dynamics, which we observe within certain ranges of model parameter values. We then explore the question of whether one can, using observed voltage data alone, estimate the states and parameters of the voltage plus calcium (V+Ca) dynamics model. We find the answer is negative. Indeed, we show that voltage plus another observed quantity must be known to allow the estimation to be accurate. We show that observing both the voltage time course V(t) and the intracellular Ca time course will permit accurate estimation, and from the estimated model state, accurate prediction after observations are completed. This sets the stage for how one will be able to use a more detailed model of V+Ca dynamics in neuron activity in the analysis of experimental data on individual neurons as well as functional networks in which the nodes (neurons) have these biophysical properties.

Seroprevalence of human herpes simplex, hepatitis B and epstein-barr viruses in children with acute lymphoblastic leukemia in southern iran.

PubMed

Mahjour, Seyed Babak; Ghaffarpasand, Fariborz; Fattahi, Mohammad Javad; Ghaderi, Abbas; Fotouhi Ghiam, Alireza; Karimi, Mehran

2010-12-01

To investigate the seroprevalence of Herpes Simplex Viruses (HSV1 and HSV2), Ebstein-Barr Virus (EBV) and Hepatitis B Virus (HBV) in children with acute lymphoblastic leukemia (ALL) in southern Iran. 90 patients with ALL and 90 age-sex matched healthy participants were enrolled in this study. Antibodies (IgG) against HBsAg, HSV1, HSV2, EBV different antigens including Epstein-Barr nuclear antigen-1 (EBNA-1), viral capsid antigen (VCA) and early antigen (EA) were measured by enzyme-linked immunosorbent assay (ELISA). There were 54 (60%) male and 36 (40%) female in both study groups with mean age of 8.47 ± 3.61 and 8.61 ± 2.84 years in case and control group respectively (P = 0.812). The prevalence of antibodies against HBsAg (P = 0.002), HSV1 (P < 0.0001), VCA (P = 0.021) and EA (P < 0.0001) antigens of EBV were significantly higher in ALL patients. With the results of this study, we could not exclude a connection between these viral infections and later leukemogenesis in childhood ALL, although nor latent infection nor congenital infection cannot be excluded by this method.

Estimating the biophysical properties of neurons with intracellular calcium dynamics

NASA Astrophysics Data System (ADS)

Ye, Jingxin; Rozdeba, Paul J.; Morone, Uriel I.; Daou, Arij; Abarbanel, Henry D. I.

2014-06-01

We investigate the dynamics of a conductance-based neuron model coupled to a model of intracellular calcium uptake and release by the endoplasmic reticulum. The intracellular calcium dynamics occur on a time scale that is orders of magnitude slower than voltage spiking behavior. Coupling these mechanisms sets the stage for the appearance of chaotic dynamics, which we observe within certain ranges of model parameter values. We then explore the question of whether one can, using observed voltage data alone, estimate the states and parameters of the voltage plus calcium (V+Ca) dynamics model. We find the answer is negative. Indeed, we show that voltage plus another observed quantity must be known to allow the estimation to be accurate. We show that observing both the voltage time course V (t) and the intracellular Ca time course will permit accurate estimation, and from the estimated model state, accurate prediction after observations are completed. This sets the stage for how one will be able to use a more detailed model of V+Ca dynamics in neuron activity in the analysis of experimental data on individual neurons as well as functional networks in which the nodes (neurons) have these biophysical properties.

Crystallization of a Keplerate-type polyoxometalate into a superposed kagome-lattice with huge channels.

PubMed

Saito, Masaki; Ozeki, Tomoji

2012-09-07

Crystal structures of two Sr(2+) salts of the Keplerate-type polyoxometalate, [Mo(VI)(72)Mo(V)(60)O(372)(CH(3)COO)(30)(H(2)O)(72)](42-), have been determined by single crystal X-ray diffraction. One compound exhibits a superposed kagome-lattice with huge channels whose diameters measure approximately 3.0 nm, while the arrangement of the Keplerate anions in the other compound approximates to a distorted cubic close packing.

Positioning Vascularized Composite Allotransplantation within the Spectrum of Transplantation

DTIC Science & Technology

2015-10-01

1 AWARD NUMBER: W81XWH-13-2-0057 TITLE: Positioning Vascularized Composite Allotransplantation within the Spectrum of Transplantation...Positioning Vascularized Composite Allotransplantation within the Spectrum of Transplantation 5b. GRANT NUMBER W81XWH-13-2-0057 5c. PROGRAM ELEMENT...Finally in Aim 8 we will develop standardization of protocols and clinical monitoring and treatment for VCA targeting vascular health. hand and face

A novel role for WAVE1 in controlling actin network growth rate and architecture

PubMed Central

Sweeney, Meredith O.; Collins, Agnieszka; Padrick, Shae B.; Goode, Bruce L.

2015-01-01

Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 (“V”) domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2. PMID:25473116

[A case of acute cerebellar ataxia following infectious mononucleosis accompanied by intrathecal anti-glutamate receptor δ2 antibody].

PubMed

Murakami, Hidetomo; Iijima, Shoji; Kawamura, Mitsuru; Takahashi, Yukitoshi; Ichikawa, Hiroo

2013-01-01

An 18-year-old woman was admitted because of sore throat and pain in the epigastric region. On admission, she presented with swollen tonsils and hepatosplenomegaly. Blood examinations revealed the presence of atypical lymphocytes, liver damage and anti-VCA IgM and IgG antibodies. These findings led to diagnosis of infectious mononucleosis. After admission, her condition improved, but on hospital day 4, she suddenly developed cerebellar ataxia in the trunk and four limbs. Cranial MRI findings were normal. Cerebrospinal fluid (CSF) collected on hospital day 6 showed normal cell counts and normal concentrations of protein and glucose. EB virus DNA and anti-VCA IgM and IgG antibodies were negative and glutamate receptor δ2 antibody was positive in CSF collected on hospital day 11. We diagnosed acute cerebellar ataxia (ACA) and performed methylprednisolone pulse therapy. After this therapy, her cerebellar ataxia improved over a few days. This is the first reported case of ACA after EB virus infection presenting with glutamate receptor δ2 antibody in CSF. The glutamate receptor δ2 subunit is expressed on cerebellar Purkinje cells. Therefore, the presence of the antibody may be associated with cerebellar dysfunction. In the present case, secondary immune reactions after EB virus infection may have produced the antibody.

Elasticity and Strength of Biomacromolecular Crystals: Lysozyme

NASA Technical Reports Server (NTRS)

Holmes, A. M.; Witherow, W. K.; Chen, L. Q.; Chernov, A. A.

2003-01-01

The static Young modulus, E = 0.1 to 0.5 GPa, the crystal critical strength (sigma(sub c)) and its ratio to E,sigma(sub c)/E is approximately 10(exp 3), were measured for the first time for non cross-linked lysozyme crystals in solution. By using a triple point bending apparatus, we also demonstrated that the crystals were purely elastic. Softness of protein crystals built of hard macromolecules (26 GPa for lysozyme) is explained by the large size of the macromolecules as compared to the range of intermolecular forces and by the weakness of intermolecular bonds as compared to the peptide bond strength. The relatively large reported dynamic elastic moduli (approximately 8 GPa) from resonance light scattering should come from averaging over the moduli of intracrystalline water and intra- and intermolecular bonding.

X-Ray Diffraction and Imaging Study of Imperfections of Crystallized Lysozyme with Coherent X-Rays

NASA Technical Reports Server (NTRS)

Hu, Zheng-Wei; Chu, Y. S.; Lai, B.; Cai, Z.; Thomas, B. R.; Chernov, A. A.

2003-01-01

Phase-sensitive x-ray diffraction imaging and high angular-resolution diffraction combined with phase contrast radiographic imaging are employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in symmetric Laue case. The fill width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal is approximately 16.7 arcseconds, and defects, which include point defects, line defects, and microscopic domains, have been clearly observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <110> growth front, and they have been found to originate mostly at a central growth area and occasionally at outer growth regions. Individual point defects trapped at a crystal nucleus are resolved in the images of high sensitivity to defects. Slow dehydration has led to the broadening of the 4 4 0 rocking curve by a factor of approximately 2.4. A significant change of the defect structure and configuration with drying has been revealed, which suggests the dehydration induced migration and evolution of dislocations and lattice rearrangements to reduce overall strain energy. The sufficient details of the observed defects shed light upon perfection, nucleation and growth, and properties of protein crystals.

High-resolution electron microscopy and its applications.

PubMed

Li, F H

1987-12-01

A review of research on high-resolution electron microscopy (HREM) carried out at the Institute of Physics, the Chinese Academy of Sciences, is presented. Apart from the direct observation of crystal and quasicrystal defects for some alloys, oxides, minerals, etc., and the structure determination for some minute crystals, an approximate image-contrast theory named pseudo-weak-phase object approximation (PWPOA), which shows the image contrast change with crystal thickness, is described. Within the framework of PWPOA, the image contrast of lithium ions in the crystal of R-Li2Ti3O7 has been observed. The usefulness of diffraction analysis techniques such as the direct method and Patterson method in HREM is discussed. Image deconvolution and resolution enhancement for weak-phase objects by use of the direct method are illustrated. In addition, preliminary results of image restoration for thick crystals are given.

The Role ERG and CXCR4 in Prostate Cancer Progression

DTIC Science & Technology

2011-06-01

axis functions in PC progression to enhance invasion and metastasis. To address the regulation of CXCR4 expression, we identified several putative ERG...interaction between ERG factor and CXCR4 gene promoter and link these activities with TMPRSS2-ERG translocations and enhanced metastasis of tumor cells via...and increased VCaP nuclear extract protein in assay enhanced the intensity of bands (Figure 1D). Inclusion of anti-ERG antibodies super shifted

ETS Gene Fusions as Predictive Biomarkers of Resistance to Radiation Therapy for Prostate Cancer

DTIC Science & Technology

2013-08-01

confocal microscopy to characterize the timing, location, and order of recruitment of the ERG-DNAPK interaction in relation to radiation delivery. In the...DNAPK linked to different fluorescent proteins, and Subtask #5B was to overexpress these constructs in the VCaP cell line and perform real-time...first half of year 3, we generated fusion constructs of ERG to various fluorescent proteins [green fluorescent protein (GFP), yellow fluorescent

Novel strategies to improve immunomodulation and non invasive clinical monitoring in VCA

DTIC Science & Technology

2017-08-01

and motor vehicle accidents, amongst others. People with these types of traumatic injuries have decreased quality of life, and are often disabled ...ability to restore form and function after these injuries. Disability with associated long-term medical care and disability benefit costs is common...entirely new IRB protocol that is specific and inclusive only of the work stated in the Statement of Work for this award. This protocol has been

Multiwavelength ultralow-threshold lasing in quantum dot photonic crystal microcavities.

PubMed

Chakravarty, S; Bhattacharya, P; Chakrabarti, S; Mi, Z

2007-05-15

We demonstrate multiwavelength lasing of resonant modes in linear (L3) microcavities in a triangular-lattice 2D photonic crystal (PC) slab. The broad spontaneous emission spectrum from coupled quantum dots, modified by the PC microcavity, is studied as a function of the intensity of incident optical excitation. We observe lasing with an ultralow-threshold power of approximately 600 nW and an output efficiency of approximately 3% at threshold. Two other resonant modes exhibit weaker turnon characteristics and thresholds of approximately 2.5 and 200 microW, respectively.

Lithographic fine-tuning of vertical cavity surface emitting laser-pumped two-dimensional photonic crystal lasers.

PubMed

Cao, J R; Lee, Po-Tsung; Choi, Sang-Jun; O'Brien, John D; Dapkus, P Daniel

2002-01-01

Lithographic tuning of operating wavelengths in a photonic crystal laser array is demonstrated. The photonic crystal lattice constant is varied by 2 nm between elements of the array, and a wavelength spacing of approximately 4 nm is achieved.

Effects of emulsifier addition on the crystallization and melting behavior of palm olein and coconut oil.

PubMed

Maruyama, Jessica Mayumi; Soares, Fabiana Andreia Schafer De Martini; D'Agostinho, Natalia Roque; Gonçalves, Maria Inês Almeida; Gioielli, Luiz Antonio; da Silva, Roberta Claro

2014-03-12

Two commercial emulsifiers (EM1 and EM2), containing predominantly monoacylglycerols (MAGs), were added in proportiond of 1.0 and 3.0% (w/w) to coconut oil and palm olein. EM1 consisted of approximately 90% MAGs, whereas EM2 consisted of approximately 50% MAGs. The crystallization behavior of these systems was evaluated by differential scanning calorimetry (DSC) and microscopy under polarized light. On the basis of DSC results, it was clear that the addition of EM2 accelerated the crystallization of coconut oil and delayed the crystallization of palm olein. In both oils EM2 addition led to the formation of smaller spherulites, and these effects improved the possibilities for using these fats as ingredients. In coconut oil the spherulites were maintained even at higher temperatures (20 °C). The addition of EM1 to coconut oil changed the crystallization pattern. In palm olein, the addition of 3.0% (w/w) of this emulsifier altered the pattern of crystallization of this fat.

Method for characterization of a spherically bent crystal for K.alpha. X-ray imaging of laser plasmas using a focusing monochromator geometry

DOEpatents

Kugland, Nathan; Doeppner, Tilo; Glenzer, Siegfried; Constantin, Carmen; Niemann, Chris; Neumayer, Paul

2015-04-07

A method is provided for characterizing spectrometric properties (e.g., peak reflectivity, reflection curve width, and Bragg angle offset) of the K.alpha. emission line reflected narrowly off angle of the direct reflection of a bent crystal and in particular of a spherically bent quartz 200 crystal by analyzing the off-angle x-ray emission from a stronger emission line reflected at angles far from normal incidence. The bent quartz crystal can therefore accurately image argon K.alpha. x-rays at near-normal incidence (Bragg angle of approximately 81 degrees). The method is useful for in-situ calibration of instruments employing the crystal as a grating by first operating the crystal as a high throughput focusing monochromator on the Rowland circle at angles far from normal incidence (Bragg angle approximately 68 degrees) to make a reflection curve with the He-like x-rays such as the He-.alpha. emission line observed from a laser-excited plasma.

Superconductor-to-insulator transition and transport properties of underdoped YBa2Cu3O(y) crystals.

PubMed

Semba, K; Matsuda, A

2001-01-15

The carrier-concentration-driven superconductor-to-insulator (SI) transition as well as transport properties in underdoped YBa2Cu3O(y) twinned crystals is studied. The SI transition takes place at y approximately 6.3, carrier concentration n(SI)H approximately 3x10(20) cm(-3), anisotropy rho(c)/rho(ab) approximately 10(3), and the threshold resistivity rho(SI)ab approximately 0.8 mOmega cm which corresponds to a critical sheet resistance h/4e2 approximately 6.5 kOmega per CuO2 bilayer. The evolution of a carrier, nH infiniti y - 6.2, is clearly observed in the underdoped region. The resistivity and Hall coefficient abruptly acquire strong temperature dependence at y approximately 6.5 indicating a radical change in the electronic state.

Fluorescence Studies of Protein Crystal Nucleation

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Sumida, John

2000-01-01

One of the most powerful and versatile methods for studying molecules in solution is fluorescence. Crystallization typically takes place in a concentrated solution environment, whereas fluorescence typically has an upper concentration limit of approximately 1 x 10(exp -5)M, thus intrinsic fluorescence cannot be employed, but a fluorescent probe must be added to a sub population of the molecules. However the fluorescent species cannot interfere with the self-assembly process. This can be achieved with macromolecules, where fluorescent probes can be covalently attached to a sub population of molecules that are subsequently used to track the system as a whole. We are using fluorescence resonance energy transfer (FRET) to study the initial solution phase self-assembly process of tetragonal lysozyme crystal nucleation, using covalent fluorescent derivatives which crystallize in the characteristic P432121 space group. FRET studies are being carried out between cascade blue (CB-lys, donor, Ex 376 nm, Em 420 nm) and lucifer yellow (LY-lys, acceptor, Ex 425 nm, Em 520 nm) asp101 derivatives. The estimated R0 for this probe pair, the distance where 50% of the donor energy is transferred to the acceptor, is approximately 1.2 nm, compared to 2.2 nm between the side chain carboxyls of adjacent asp101's in the crystalline 43 helix. The short CB-lys lifetime (approximately 5 ns), coupled with the large average distances between the molecules ((sup 3) 50 nm) in solution, ensure that any energy transfer observed is not due to random diffusive interactions. Addition of LY-lys to CB-lys results in the appearance of a second, shorter lifetime (approximately 0.2 ns). Results from these and other ongoing studies will be discussed in conjunction with a model for how tetragonal lysozyme crystals nucleate and grow, and the relevance of that model to microgravity protein crystal growth

Evaluation of a new reagent for anti-cytomegalovirus and anti-Epstein-Barr virus immunoglobulin G.

PubMed Central

Gutierrez, J; Maroto, M D; Piédrola, G

1994-01-01

The Enzygnost alpha method was tested against the complement fixation test and anti-VCA immunofluorescence to determine the respective titers of anti-cytomegalovirus and anti-Epstein-Barr virus immunoglobulin G antibodies. For cytomegalovirus, the Enzygnost results showed 97.99% agreement with the readings obtained by the alternative method, with 100% sensitivity and 93.7% specificity. For Epstein-Barr virus, Enzygnost showed 97.71% agreement, 100% sensitivity, and 91.11% specificity. PMID:7814510

Upper extremity transplantation: current concepts and challenges in an emerging field.

PubMed

Elliott, River M; Tintle, Scott M; Levin, L Scott

2014-03-01

Loss of an isolated upper limb is an emotionally and physically devastating event that results in significant impairment. Patients who lose both upper extremities experience profound disability that affects nearly every aspect of their lives. While prosthetics and surgery can eventually provide the single limb amputee with a suitable assisting hand, limited utility, minimal haptic feedback, weight, and discomfort are persistent problems with these techniques that contribute to high rates of prosthetic rejection. Moreover, despite ongoing advances in prosthetic technology, bilateral amputees continue to experience high levels of dependency, disability, and distress. Hand and upper extremity transplantation holds several advantages over prosthetic rehabilitation. The missing limb is replaced with one of similar skin color and size. Sensibility, voluntary motor control, and proprioception are restored to a greater degree, and afford better dexterity and function than prosthetics. The main shortcomings of transplantation include the hazards of immunosuppression, the complications of rejection and its treatment, and high cost. Hand and upper limb transplantation represents the most commonly performed surgery in the growing field of Vascularized Composite Allotransplantation (VCA). As upper limb transplantation and VCA have become more widespread, several important challenges and controversies have emerged. These include: refining indications for transplantation, optimizing immunosuppression, establishing reliable criteria for monitoring, diagnosing, and treating rejection, and standardizing outcome measures. This article will summarize the historical background of hand transplantation and review the current literature and concepts surrounding it.

An ELISA method to compute endpoint titers to Epstein-Barr virus and cytomegalovirus: application to population-based studies.

PubMed

Stowe, Raymond P; Ruiz, R Jeanne; Fagundes, Christopher P; Stowe, Robin H; Chen, Min; Glaser, Ronald

2014-06-01

Indirect fluorescence analysis (IFA), the gold standard for determining herpesvirus antibody titers, is labor-intensive and poorly suited for large population-based studies. The enzyme-linked immunosorbent assay (ELISA) is used widely for measuring antiviral antibodies but also suffers drawbacks such as reduced specificity and the qualitative nature of the results due to limited interpretation of the optical density (OD) units. This paper describes a method to titer herpesvirus antibodies using microplates coated with virally-infected cells in which a standard curve, derived from IFA-scored samples, allowed OD units to be converted into titers. A LOOKUP function was created in order to report the data as traditional IFA-based (i.e., 2-fold) titers. The modified ELISA correlated significantly with IFA and was subsequently used to compute endpoint antibody titers to Epstein-Barr virus (EBV)-virus capsid antigen (VCA) and cytomegalovirus (CMV) in blood samples taken from 398 pregnant Hispanic women. Four women were EBV negative (1%), while 58 women were CMV negative (14.6%). EBV VCA antibody titers were significantly higher than CMV antibody titers (p<0.001). This method allows titering of herpesvirus antibodies by ELISA suitable for large population-based studies. In addition, the LOOKUP table enables conversion from OD-derived titers into 2-fold titers for comparison of results with other studies. Copyright © 2014 Elsevier B.V. All rights reserved.

[Acute cerebellar ataxia associated with infectious mononucleosis--a case report and review of the literature].

PubMed

Yabuki, S; Kazahaya, Y; Ikeda, K

1983-04-01

A 20-year-old man, a college student, was admitted to Kochi Municipal Central Hospital with a month's history of slurring of speech and unsteadiness of gait. He had developed fever, sore throat and cervical lymphadenopathy. On admission, the throat was mildly injected, and enlarged lymph nodes were palpable in the lateral cervical regions. His speech was slightly slurred. Bilateral dysmetria, dyssynergia and intention tremor were noted in both extremities. The gait was grossly ataxic. Plantar responses were extensor. Examination of his peripheral blood revealed atypical lymphocytes, and the titer of Paul-Bunnell was 1:16. The CSF protein was 25 mg/dl with normal cell count. Epstein-Barr virus (EBV) antibody titers by indirect immunofluorescence in the serum of the second hospital day were as follows: VCA-IgG was 1:640, VCA-IgM less than 1:10, EBV-EA 1:160, and EBNA less than 1:10, while the CSF-EBV antibody titer was negative. Treatment with prednisolone was started and within 7 days he began to recover. Six weeks after admission he was completely free of neurological symptoms and signs. We also reviewed 18 cases of acute cerebellar ataxia with infectious mononucleosis in the literature. It was postulated that the neurological symptoms complicating infectious mononucleosis were possibly caused by infectious and immuno-allergic mechanisms.

Mechanisms of 200 MeV electron radiation in diamond crystal in the axial orientation

NASA Astrophysics Data System (ADS)

Ganenko, V. B.; Burdeinyi, D. D.; Truten', V. I.; Shul'ga, N. F.; Fissum, K.; Brudvik, J.; Hansen, K.; Isaksson, L.; Livingston, K.; Lundin, M.; Nilsson, B.; Schroder, B.

2018-06-01

The γ -radiation by electrons with the energy of ∼ 200 MeV in a 100 μ m-thick diamond crystal has been measured at the MAX-lab experimental facility, when the electrons are incident on the crystal along the < 100 > axis. In this case, the intensity of the -radiation with the energy ∼ 1-2 MeV is approximately 16 times higher than that in amorphous matter of the same thickness. Theoretical calculations based on the quasi-classical QED approximation are in good agreement with the experimental data. The analysis of the radiation mechanisms has shown that the main contribution to the radiation intensity resulted from electrons, moving in the above-barrier regime and at small angles to the crystal axis.

Cohesive Energy-Lattice Constant and Bulk Modulus-Lattice Constant Relationships: Alkali Halides, Ag Halides, Tl Halides

NASA Technical Reports Server (NTRS)

Schlosser, Herbert

1992-01-01

In this note we present two expressions relating the cohesive energy, E(sub coh), and the zero pressure isothermal bulk modulus, B(sub 0), of the alkali halides. Ag halides and TI halides, with the nearest neighbor distances, d(sub nn). First, we show that the product E(sub coh)d(sub 0) within families of halide crystals with common crystal structure is to a good approximation constant, with maximum rms deviation of plus or minus 2%. Secondly, we demonstrate that within families of halide crystals with a common cation and common crystal structure the product B(sub 0)d(sup 3.5)(sub nn) is a good approximation constant, with maximum rms deviation of plus or minus 1.36%.

Studies of Nucleation, Growth, Specific Heat, and Viscosity of Undercooled Melts of Quasicrystals and Polytetrahedral-Phase-Forming Alloys

NASA Technical Reports Server (NTRS)

Kelton, K. F.; Croat, T. K.; Gangopadhyay, A.; Holland-Moritz, D.; Hyers, Robert W.; Rathz, Thomas J.; Robinson, Michael B.; Rogers, Jan R.

2001-01-01

Undercooling experiments and thermal physical property measurements of metallic alloys on the International Space Station (ISS) are planned. This recently-funded research focuses on fundamental issues of the formation and structure of highly-ordered non-crystallographic phases (quasicrystals) and related crystal phases (crystal approximants), and the connections between the atomic structures of these phases and those of liquids and glasses. It extends studies made previously by us of the composition dependence of crystal nucleation processes in silicate and metallic glasses, to the case of nucleation from the liquid phase. Motivating results from rf-levitation and drop-tube measurements of the undercooling of Ti/Zr-based liquids that form quasicrystals and crystal approximants are discussed. Preliminary measurements by electrostatic levitation (ESL) are presented.

The diagram of phase-field crystal structures: an influence of model parameters in a two-mode approximation

NASA Astrophysics Data System (ADS)

Ankudinov, V.; Galenko, P. K.

2017-04-01

Effect of phase-field crystal model (PFC-model) parameters on the structure diagram is analyzed. The PFC-model is taken in a two-mode approximation and the construction of structure diagram follows from the free energy minimization and Maxwell thermodynamic rule. The diagram of structure’s coexistence for three dimensional crystal structures [Body-Centered-Cubic (BCC), Face-Centered-Cubic (FCC) and homogeneous structures] are constructed. An influence of the model parameters, including the stability parameters, are discussed. A question about the structure diagram construction using the two-mode PFC-model with the application to real materials is established.

Iridescence and spectral filtering of the gyroid-type photonic crystals in Parides sesostris wing scales

PubMed Central

Wilts, Bodo D.; Michielsen, Kristel; De Raedt, Hans; Stavenga, Doekele G.

2012-01-01

The cover scales on the wing of the Emerald-patched Cattleheart butterfly, Parides sesostris, contain gyroid-type biological photonic crystals that brightly reflect green light. A pigment, which absorbs maximally at approximately 395 nm, is immersed predominantly throughout the elaborate upper lamina. This pigment acts as a long-pass filter shaping the reflectance spectrum of the underlying photonic crystals. The additional effect of the filtering is that the spatial distribution of the scale reflectance is approximately angle-independent, leading to a stable wing pattern contrast. The spectral tuning of the original reflectance is verified by photonic band structure modelling. PMID:24098853

Diffraction and imaging study of imperfections of crystallized lysozyme with coherent X-rays

NASA Technical Reports Server (NTRS)

Hu, Z. W.; Chu, Y. S.; Lai, B.; Thomas, B. R.; Chernov, A. A.

2004-01-01

Phase-contrast X-ray diffraction imaging and high-angular-resolution diffraction combined with phase-contrast radiographic imaging were employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in the symmetric Laue case. The full-width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal was approximately 16.7 arcsec and imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <1 1 0> growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Inclusions of impurities or formations of foreign particles in the central growth region are resolved in the images with high sensitivity to defects. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in X-ray diffraction images. The details of the observed defects and the significant change in the revealed microstructures with drying provide insight into the nature of imperfections, nucleation and growth, and the properties of protein crystals.

Paramagnetic resonance and susceptibility of ilmenite, FeTiO3 crystal

NASA Technical Reports Server (NTRS)

Mcdonald, P. F.; Parasiris, A.; Pandey, R. K.; Gries, B. L.; Kirk, W. P.

1991-01-01

Large high-purity single crystals of FeTiO3 with ilmenite structure have been grown from a stoichiometric melt of Fe2O3 and TiO2 under an inert atmosphere using the modified Czochralski technique. Susceptibility and X-band paramagnetic resonance studies have been performed. Susceptibility measurements indicate a Neel temperature of about 59 K. The paramagnetic resonance spectrum for magnetic field perpendicular to the crystal c axis consists of a portion of a single, very intense approximately Lorentzian absorption line with its peak at about 600 G and half width at half maximum almost 1200 G. The absorption extends to zero magnetic field. For magnetic field approximately parallel to the c axis, the paramagnetic absorption is much smaller and may be considered a superposition of two approximately Lorentzian line shapes. The magnetic resonance measurements indicate a weak temperature dependence and large angular anisotropy.

Laboratory Annealing Experiments Of Refractory Silicate Grain Analogs Using Differential Scanning Calorimetry

NASA Technical Reports Server (NTRS)

Kimura, Yuki; Nuth, Joseph A., III; Tsukamota, Katsuo; Kaito, Chihiro

2010-01-01

Exothermic reactions during the annealing of laboratory synthesized amorphous magnesium-bearing silicate particles used as grain analogs of cosmic dust were detected by differential scanning calorimetry (DSC) in air. With infrared spectroscopy and transmission electron microscopy, we show that cosmic dust could possibly undergo fusion to larger particles, with oxidation of magnesium silicide and crystallization of forsterite as exothermic reactions in the early solar system. The reactions begin at approximately 425, approximately 625, and approximately 1000 K, respectively, and the reaction energies (enthalpies) are at least 727, 4151, and 160.22 J per gram, respectively. During the crystallization of forsterite particles, the spectral evolution of the 10 micrometer feature from amorphous to crystalline was observed to begin at lower temperature than the crystallization temperature of 1003 K. During spectral evolution at lower temperature, nucleation and/or the formation of nanocrystallites of forsterite at the surface of the grain analogs was observed.

Numerical Study of Hydrothermal Wave Suppression in Thermocapillary Flow Using a Predictive Control Method

NASA Astrophysics Data System (ADS)

Muldoon, F. H.

2018-04-01

Hydrothermal waves in flows driven by thermocapillary and buoyancy effects are suppressed by applying a predictive control method. Hydrothermal waves arise in the manufacturing of crystals, including the "open boat" crystal growth process, and lead to undesirable impurities in crystals. The open boat process is modeled using the two-dimensional unsteady incompressible Navier-Stokes equations under the Boussinesq approximation and the linear approximation of the surface thermocapillary force. The flow is controlled by a spatially and temporally varying heat flux density through the free surface. The heat flux density is determined by a conjugate gradient optimization algorithm. The gradient of the objective function with respect to the heat flux density is found by solving adjoint equations derived from the Navier-Stokes ones in the Boussinesq approximation. Special attention is given to heat flux density distributions over small free-surface areas and to the maximum admissible heat flux density.

Positioning Vascularized Composite Allotransplantation in the Spectrum of Transplantation

DTIC Science & Technology

2017-10-01

have now shown that the efficacy of both protocols is dependent upon a radiation-sensitive donor bone marrow (BM) cell type that is of T or B cell... dependent VCA survival. IL-2C Therapy Increases the Number but Not Function of Foxp3 CD4+ Treg Cells To test the effects of JES6-1 mAb-based IL-2C...which Treg cell- dependent immunoregulation has considerable potential. These IL-2C studies are now “in press” (4). TASK 5: OPTIMAL COMBINATION

The Role of AR- and VDR-Modulated miRNAs in Sensitization of Prostate Cancer Cells to Therapy

DTIC Science & Technology

2012-10-01

detected elevated levels of the AR-V7 variant in VCaP xenografts after castration (109). Prostate epithelial markers, cytokeratin 8 and 18 , are expressed...OF: 17. LIMITATION OF ABSTRACT 18 . NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON USAMRMC a. REPORT U b. ABSTRACT U c. THIS PAGE U...Author. 6) Gaupel AC1, Wang WLW1, Mordan-McCombs S, Lee ECY & Tenniswood M. Xenograft , transgenic and knockout models of prostate cancer. In: Conn

Functions of Tenascin-C and Integrin alpha9beta1 in Mediating Prostate Cancer Bone Metastasis

DTIC Science & Technology

2017-10-01

additional engineered cell lines for verification and we plan to also generate stable knockout cell lines using CRISPR /Cas 9 gene editing technology...addition to the proposed study, we plan to also produce VCaP cells that are null (knockout) for alpha 9 integrin using CRISPR /Cas9 gene editing protocols...We are experienced with CRISPR -Cas knockdown and have successfully engineered cells previously. We do not expect any particular difficulty in

Functional Characterization of the Protein Product of the Prostate Carcinoma Gene Fusion TMPRSS2:ERG Using the Proteomic and Microarray Analyses

DTIC Science & Technology

2009-07-01

AD_________________ ( Leave blank) Award Number: W81XWH-08-1-0048 TITLE: Functional...cancer human cell lines, T98G and U2OS, in order to test for cell-line specific effects . After infecting equal number of cells with the viruses carrying... Guava ™ FACS analyzer with the ViaCount™ kit (Millipore). As shown in Fig. 7, VCaP cells infected with ERG or ERGa once again failed to proliferate

Surface heat shock protein 90 serves as a potential receptor for calcium oxalate crystal on apical membrane of renal tubular epithelial cells.

PubMed

Fong-Ngern, Kedsarin; Sueksakit, Kanyarat; Thongboonkerd, Visith

2016-07-01

Adhesion of calcium oxalate monohydrate (COM) crystals on renal tubular epithelial cells is a crucial step in kidney stone formation. Finding potential crystal receptors on the apical membrane of the cells may lead to a novel approach to prevent kidney stone disease. Our previous study identified a large number of crystal-binding proteins on the apical membrane of MDCK cells. However, their functional role as potential crystal receptors had not been validated. The present study aimed to address the potential role of heat shock protein 90 (HSP90) as a COM crystal receptor. The apical membrane was isolated from polarized MDCK cells by the peeling method and recovered proteins were incubated with COM crystals. Western blot analysis confirmed the presence of HSP90 in the apical membrane and the crystal-bound fraction. Immunofluorescence staining without permeabilization and laser-scanning confocal microscopy confirmed the surface HSP90 expression on the apical membrane of the intact cells. Crystal adhesion assay showed that blocking surface HSP90 by specific anti-HSP90 antibody and knockdown of HSP90 by small interfering RNA (siRNA) dramatically reduced crystal binding on the apical surface of MDCK cells (by approximately 1/2 and 2/3, respectively). Additionally, crystal internalization assay revealed the presence of HSP90 on the membrane of endocytic vesicle containing the internalized COM crystal. Moreover, pretreatment of MDCK cells with anti-HSP90 antibody significantly reduced crystal internalization (by approximately 1/3). Taken together, our data indicate that HSP90 serves as a potential receptor for COM crystals on the apical membrane of renal tubular epithelial cells and is involved in endocytosis/internalization of the crystals into the cells.

Thermoelectric properties of nanocrystalline Sb2Te3 thin films: experimental evaluation and first-principles calculation, addressing effect of crystal grain size.

PubMed

Morikawa, Satoshi; Inamoto, Takuya; Takashiri, Masayuki

2018-02-16

The effect of crystal grain size on the thermoelectric properties of nanocrystalline antimony telluride (Sb 2 Te 3 ) thin films was investigated by experiments and first-principles studies using a developed relaxation time approximation. The Sb 2 Te 3 thin films were deposited on glass substrates using radio-frequency magnetron sputtering. To change the crystal grain size of the Sb 2 Te 3 thin films, thermal annealing was performed at different temperatures. The crystal grain size, lattice parameter, and crystal orientation of the thin films were estimated using XRD patterns. The carrier concentration and in-plane thermoelectric properties of the thin films were measured at room temperature. A theoretical analysis was performed using a first-principles study based on density functional theory. The electronic band structures of Sb 2 Te 3 were calculated using different lattice parameters, and the thermoelectric properties were predicted based on the semi-classical Boltzmann transport equation in the relaxation time approximation. In particular, we introduced the effect of carrier scattering at the grain boundaries into the relaxation time approximation by estimating the group velocities from the electronic band structures. Finally, the experimentally measured thermoelectric properties were compared with those obtained by calculation. As a result, the calculated thermoelectric properties were found to be in good agreement with the experimental results. Therefore, we can conclude that introducing the effect of carrier scattering at the grain boundaries into the relaxation time approximation contributes to enhance the accuracy of a first-principles calculation relating to nanocrystalline materials.

Thermoelectric properties of nanocrystalline Sb2Te3 thin films: experimental evaluation and first-principles calculation, addressing effect of crystal grain size

NASA Astrophysics Data System (ADS)

Morikawa, Satoshi; Inamoto, Takuya; Takashiri, Masayuki

2018-02-01

The effect of crystal grain size on the thermoelectric properties of nanocrystalline antimony telluride (Sb2Te3) thin films was investigated by experiments and first-principles studies using a developed relaxation time approximation. The Sb2Te3 thin films were deposited on glass substrates using radio-frequency magnetron sputtering. To change the crystal grain size of the Sb2Te3 thin films, thermal annealing was performed at different temperatures. The crystal grain size, lattice parameter, and crystal orientation of the thin films were estimated using XRD patterns. The carrier concentration and in-plane thermoelectric properties of the thin films were measured at room temperature. A theoretical analysis was performed using a first-principles study based on density functional theory. The electronic band structures of Sb2Te3 were calculated using different lattice parameters, and the thermoelectric properties were predicted based on the semi-classical Boltzmann transport equation in the relaxation time approximation. In particular, we introduced the effect of carrier scattering at the grain boundaries into the relaxation time approximation by estimating the group velocities from the electronic band structures. Finally, the experimentally measured thermoelectric properties were compared with those obtained by calculation. As a result, the calculated thermoelectric properties were found to be in good agreement with the experimental results. Therefore, we can conclude that introducing the effect of carrier scattering at the grain boundaries into the relaxation time approximation contributes to enhance the accuracy of a first-principles calculation relating to nanocrystalline materials.

Diffraction and Imaging Study of Imperfections of Protein Crystals with Coherent X-rays

NASA Technical Reports Server (NTRS)

Hu, Z. W.; Thomas, B. R.; Chernov, A. A.; Chu, Y. S.; Lai, B.

2004-01-01

High angular-resolution x-ray diffraction and phase contrast x-ray imaging were combined to study defects and perfection of protein crystals. Imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of a uniformly grown lysozyme crystal. The observed line defects carry distinct dislocation features running approximately along the <110> growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in diffraction images. X-ray imaging and diffraction characterization of the quality of apoferritin crystals will also be discussed in the presentation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modak, Viraj P., E-mail: virajmodak@gmail.com; Wyslouzil, Barbara E., E-mail: wyslouzil.1@osu.edu; Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210

The crystal-vapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into non-interacting sub-systems with crystal-vapor interfaces. We do this by turning off the interactions, ΔV, between the sub-systems. Using the soft-core scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy inmore » terms of an average of e{sup −βΔV} in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a non-Gaussian theory for γ and find that the difference between the non-Gaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a Lennard-Jones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystal-vapor surface free energy has been of particular interest for understanding surface freezing in these systems.« less

Effects of β-sheet crystals and a glycine-rich matrix on the thermal conductivity of spider dragline silk.

PubMed

Park, Jinju; Kim, Duckjong; Lee, Seung-Mo; Choi, Ji-Ung; You, Myungil; So, Hye-Mi; Han, Junkyu; Nah, Junghyo; Seol, Jae Hun

2017-03-01

We measured the thermal conductivity of Araneus ventricosus' spider dragline silk using a suspended microdevice. The thermal conductivity of the silk fiber was approximately 0.4Wm -1 K -1 at room temperature and gradually increased with an increasing temperature in a manner similar to that of other disordered crystals or proteins. In order to elucidate the effect of β-sheet crystals in the silk, thermal denaturation was used to reduce the quantity of the β-sheet crystals. A calculation with an effective medium approximation supported this measurement result showing that the thermal conductivity of β-sheet crystals had an insignificant effect on the thermal conductivity of SDS. Additionally, the enhancement of bonding strength in a glycine-rich matrix by atomic layer deposition did not increase the thermal conductivity. Thus, this study suggests that the disordered part of the glycine-rich matrix prevented the peptide chains from being coaxially extended via the cross-linking covalent bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

Common misconceptions about the dynamical theory of crystal lattices: Cauchy relations, lattice potentials and infinite crystals

NASA Astrophysics Data System (ADS)

Elcoro, Luis; Etxebarria, Jesús

2011-01-01

The requirement of rotational invariance for lattice potential energies is investigated. Starting from this condition, it is shown that the Cauchy relations for the elastic constants are fulfilled if the lattice potential is built from pair interactions or when the first-neighbour approximation is adopted. This is seldom recognized in widely used solid-state textbooks. Frequently, pair interaction is even considered to be the most general situation. In addition, it is shown that the demand of rotational invariance in an infinite crystal leads to inconsistencies in the symmetry of the elastic tensor. However, for finite crystals, no problems arise, and the Huang conditions are deduced using exclusively a microscopic approach for the elasticity theory, without making any reference to macroscopic parameters. This work may be useful in both undergraduate and graduate level courses to point out the crudeness of the pair-potential interaction and to explore the limits of the infinite-crystal approximation.

Origin of Quantum Criticality in Yb-Al-Au Approximant Crystal and Quasicrystal

NASA Astrophysics Data System (ADS)

Watanabe, Shinji; Miyake, Kazumasa

2016-06-01

To get insight into the mechanism of emergence of unconventional quantum criticality observed in quasicrystal Yb15Al34Au51, the approximant crystal Yb14Al35Au51 is analyzed theoretically. By constructing a minimal model for the approximant crystal, the heavy quasiparticle band is shown to emerge near the Fermi level because of strong correlation of 4f electrons at Yb. We find that charge-transfer mode between 4f electron at Yb on the 3rd shell and 3p electron at Al on the 4th shell in Tsai-type cluster is considerably enhanced with almost flat momentum dependence. The mode-coupling theory shows that magnetic as well as valence susceptibility exhibits χ ˜ T-0.5 for zero-field limit and is expressed as a single scaling function of the ratio of temperature to magnetic field T/B over four decades even in the approximant crystal when some condition is satisfied by varying parameters, e.g., by applying pressure. The key origin is clarified to be due to strong locality of the critical Yb-valence fluctuation and small Brillouin zone reflecting the large unit cell, giving rise to the extremely-small characteristic energy scale. This also gives a natural explanation for the quantum criticality in the quasicrystal corresponding to the infinite limit of the unit-cell size.

Photonic crystal geometry for organic solar cells.

PubMed

Ko, Doo-Hyun; Tumbleston, John R; Zhang, Lei; Williams, Stuart; DeSimone, Joseph M; Lopez, Rene; Samulski, Edward T

2009-07-01

We report organic solar cells with a photonic crystal nanostructure embossed in the photoactive bulk heterojunction layer, a topography that exhibits a 3-fold enhancement of the absorption in specific regions of the solar spectrum in part through multiple excitation resonances. The photonic crystal geometry is fabricated using a materials-agnostic process called PRINT wherein highly ordered arrays of nanoscale features are readily made in a single processing step over wide areas (approximately 4 cm(2)) that is scalable. We show efficiency improvements of approximately 70% that result not only from greater absorption, but also from electrical enhancements. The methodology is generally applicable to organic solar cells and the experimental findings reported in our manuscript corroborate theoretical expectations.

Computing approximate solutions of the protein structure determination problem using global constraints on discrete crystal lattices.

PubMed

Dal Palù, Alessandro; Dovier, Agostino; Pontelli, Enrico

2010-01-01

Crystal lattices are discrete models of the three-dimensional space that have been effectively employed to facilitate the task of determining proteins' natural conformation. This paper investigates alternative global constraints that can be introduced in a constraint solver over discrete crystal lattices. The objective is to enhance the efficiency of lattice solvers in dealing with the construction of approximate solutions of the protein structure determination problem. Some of them (e.g., self-avoiding-walk) have been explicitly or implicitly already used in previous approaches, while others (e.g., the density constraint) are new. The intrinsic complexities of all of them are studied and preliminary experimental results are discussed.

Parametrization of semiempirical models against ab initio crystal data: evaluation of lattice energies of nitrate salts.

PubMed

Beaucamp, Sylvain; Mathieu, Didier; Agafonov, Viatcheslav

2005-09-01

A method to estimate the lattice energies E(latt) of nitrate salts is put forward. First, E(latt) is approximated by its electrostatic component E(elec). Then, E(elec) is correlated with Mulliken atomic charges calculated on the species that make up the crystal, using a simple equation involving two empirical parameters. The latter are fitted against point charge estimates of E(elec) computed on available X-ray structures of nitrate crystals. The correlation thus obtained yields lattice energies within 0.5 kJ/g from point charge values. A further assessment of the method against experimental data suggests that the main source of error arises from the point charge approximation.

Persistence of plasmids, cholera toxin genes, and prophage DNA in classical Vibrio cholerae O1.

PubMed

Cook, W L; Wachsmuth, K; Johnson, S R; Birkness, K A; Samadi, A R

1984-07-01

Plasmid profiles, the location of cholera toxin subunit A genes, and the presence of the defective VcA1 prophage genome in classical Vibrio cholerae isolated from patients in Bangladesh in 1982 were compared with those in older classical strains isolated during the sixth pandemic and with those in selected eltor and nontoxigenic O1 isolates. Classical strains typically had two plasmids (21 and 3 megadaltons), eltor strains typically had no plasmids, and nontoxigenic O1 strains had zero to three plasmids. The old and new isolates of classical V. cholerae had two HindIII chromosomal digest fragments containing cholera toxin subunit A genes, whereas the eltor strains from Eastern countries had one fragment. The eltor strains from areas surrounding the Gulf of Mexico also had two subunit A gene fragments, which were smaller and easily distinguished from the classical pattern. All classical strains had 8 to 10 HindIII fragments containing the defective VcA1 prophage genome; none of the Eastern eltor strains had these genes, and the Gulf Coast eltor strains contained a different array of weakly hybridizing genes. These data suggest that the recent isolates of classical cholera in Bangladesh are closely related to the bacterial strain(s) which caused classical cholera during the sixth pandemic. These data do not support hypotheses that either the eltor or the nontoxigenic O1 strains are precursors of the new classical strains.

Systemic GLIPR1-ΔTM protein as a novel therapeutic approach for prostate cancer.

PubMed

Karantanos, Theodoros; Tanimoto, Ryuta; Edamura, Kohei; Hirayama, Takahiro; Yang, Guang; Golstov, Alexei A; Wang, Jianxiang; Kurosaka, Shinji; Park, Sanghee; Thompson, Timothy C

2014-04-15

GLIPR1 is a p53 target gene known to be downregulated in prostate cancer, and increased endogenous GLIPR1 expression has been associated with increased production of reactive oxygen species, increased apoptosis, decreased c-Myc protein levels and increased cell cycle arrest. Recently, we found that upregulation of GLIPR1 in prostate cancer cells increases mitotic catastrophe through interaction with heat shock cognate protein 70 (Hsc70) and downregulation of Aurora kinase A and TPX2. In this study, we evaluated the mechanisms of recombinant GLIPR1 protein (glioma pathogenesis-related protein 1-transmembrane domain deleted [GLIPR1-ΔTM]) uptake by prostate cancer cells and the efficacy of systemic GLIPR1-ΔTM administration in a prostate cancer xenograft mouse model. GLIPR1-ΔTM was selectively internalized by prostate cancer cells, leading to increased apoptosis through reactive oxygen species production and to decreased c-Myc protein levels. Interestingly, GLIPR1-ΔTM was internalized through clathrin-mediated endocytosis in association with Hsc70. Systemic administration of GLIPR1-ΔTM significantly inhibited VCaP xenograft growth. GLIPR1-ΔTM showed no evidence of toxicity following elimination from mouse models 8 hr after injection. Our results demonstrate that GLIPR1-ΔTM is selectively endocytosed by prostate cancer cells, leading to increased reactive oxygen species production and apoptosis, and that systemic GLIPR1-ΔTM significantly inhibits growth of VCaP xenografts without substantial toxicity. © 2013 UICC.

A naturally occurring mixture of tocotrienols inhibits the growth of human prostate tumor, associated with epigenetic modifications of cyclin-dependent kinase inhibitors p21 and p27.

PubMed

Huang, Ying; Wu, Renyi; Su, Zheng-Yuan; Guo, Yue; Zheng, Xi; Yang, Chung S; Kong, Ah-Ng

2017-02-01

Tocotrienols, members of the vitamin E family, have three unsaturated bonds in their side chains. Recently, it has been suggested that the biological effects of tocotrienols may differ from that of tocopherols. Several in vitro studies have shown that tocotrienols have stronger anticancer effects than tocopherols. VCaP cell line used in this study is from a vertebral bone metastasis from a patient with prostate cancer. Eight-week-old male NCr(-/-) nude mice were subcutaneously injected with VCaP-luc cells in matrigel and then administered a tocotrienol mixture for 8 weeks. The tocotrienol mixture inhibited the growth of human prostate tumor xenografts in a dose-dependent manner. The concentrations of tocotrienols and their metabolites were significantly increased in treatment groups. Tocotrienols inhibited prostate tumor growth by suppressing cell proliferation, which was associated with the induction of the cyclin-dependent kinase (CDK) inhibitors p21 and p27. In addition, tocotrienol treatment was associated with elevated H3K9 acetylation levels at proximal promoter regions of p21 and p27 and with decreased expression of histone deacetylases. Tocotrienols inhibited human prostate tumor growth, associated with up-regulation of the CDK inhibitors p21 and p27. Elevated expression of p21 and p27 could be partly due to the suppressed expression of HDACs. Copyright © 2016 Elsevier Inc. All rights reserved.

Antigen-inducing ability of herpesvirus papio in human and baboon lymphoma lines, compared to Epstein-Barr virus.

PubMed

Klein, G; Falk, L; Falk, K

1978-01-01

Herpesvirus papio(HVP)-carrying baboon lymphoblastoid lines do not express a nuclear antigen like the Epstein-Barr virus(EBV)-determined nuclear antigen (EBNA), as judged by in situ anticomplement fluorescence staining, although the carry multiple viral genomes and, in the case of producerlines, early antigen (EA) and viral capsid antigen (VCA) that cross-react with the corresponding human EBV-determined antigens. To test whether the lack of in situ nuclear antigen expression is a property innate to the baboon virus or the baboon cell, nonproducer HVP-carrying baboon lymphoid cells of the 26 CB-1 line were superinfected with two human EBV strains. B95-8-derived EBV induced brilliant EBNA staining, proving that the baboon lymphoid cell was competent to synthesize EBNA. In the mirror experiment, HVP derived from the 9B or the 18C baboon line was added to the EBV-carrying Raji line, the EBV-negative Ramos and BJAB lines and the HVP-carrying nonproducer 26 CB-1 line, respectively. HVP induced EA and VCA in Raji, and EA in BJAB and 26 CB-1. EBNA was not induced in any of the three EBNA-negative lines, BJAB, Ramos and 26 CB-1. It is concluded that the lack of in situ nuclear staining in HVP-carrying baboon lines is a HVP-associated property and is not due to any innate inability of the baboon lymphoid cell to synthesize an antigen of the EBNA type.

Crystallization of Chicken Egg White Lysozyme from Assorted Sulfate Salts

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Snell, Edward H.; Malone, Christine C.; Pusey, Marc L.

1999-01-01

Chicken egg white lysozyme has been found to crystallize from ammonium, sodium, potassium, rubidium, magnesium, and manganese sulfates at acidic and basic pH, with protein concentrations from 60 to 190 mg/ml. Crystals have also been grown at 4 C in the absence of any other added salts using isoionic lysozyme which was titrated to pH 4.6 with dilute sulfuric acid. Four different crystal forms have been obtained, depending upon the temperature, protein concentration, and precipitating salt employed. Crystals grown at 15 C were generally tetragonal, with space group P4(sub 3)2(sub 1)2. Crystallization at 20 C typically resulted in the formation of orthorhombic crystals, space group P2(sub 1)2(sub 1)2(sub 1). The tetragonal reversible reaction orthorhombic transition appeared to be a function of both the temperature and protein concentration, occurring between 15 and 20 C and between 100 and 125 mg/ml protein concentration. Crystallization from 1.2 M magnesium sulfate at pH 7.8 gave a trigonal crystal, space group P3(sub 1)2(sub 1), a = b = 87.4, c = 73.7, gamma = 120 deg, which diffracted to 2.8 A. Crystallization from ammonium sulfate at pH 4.6, generally at lower temperatures, was also found to result in a monoclinic form. space group C2, a = 65.6, b = 95.0, c = 41.2, beta = 119.2 deg. A crystal of approximately 0.2 x 0.2 x 0.5 mm grown from bulk solution diffracted to approximately 3.5 A.

The Kinetics of Crystallization of Colloids and Proteins: A Light Scattering Study

NASA Technical Reports Server (NTRS)

McClymer, Jim

2002-01-01

Hard-sphere colloidal systems serve as model systems for aggregation, nucleation, crystallization and gelation as well as interesting systems in their own right.There is strong current interest in using colloidal systems to form photonic crystals. A major scientific thrust of NASA's microgravity research is the crystallization of proteins for structural determination. The crystallization of proteins is a complicated process that requires a great deal of trial and error experimentation. In spite of a great deal of work, "better" protein crystals cannot always be grown in microgravity and conditions for crystallization are not well understood. Crystallization of colloidal systems interacting as hard spheres and with an attractive potential induced by entropic forces have been studied in a series of static light scattering experiments. Additionally, aggregation of a protein as a function of pH has been studied using dynamic light scattering. For our experiments we used PMMA (polymethylacrylate) spherical particles interacting as hard spheres, with no attractive potential. These particles have a radius of 304 nanometers, a density of 1.22 gm/ml and an index of refraction of 1.52. A PMMA colloidal sample at a volume fraction of approximately 54% was index matched in a solution of cycloheptyl bromide (CHB) and cis-decalin. The sample is in a glass cylindrical vial that is placed in an ALV static and dynamic light scattering goniometer system. The vial is immersed in a toluene bath for index matching to minimize flair. Vigorous shaking melts any colloidal crystals initially present. The sample is illuminated with diverging laser light (632.8 nanometers) from a 4x microscope objective placed so that the beam is approximately 1 cm in diameter at the sample location. The sample is rotated about its long axis at approximately 3.5 revolutions per minute (highest speed) as the colloidal crystal system is non-ergodic. The scattered light is detected at various angles using the ALV light detection optics, which is fed into an APD detector module and linked to a computer. The scattering angle (between 12 and 160 degrees), scattering angle step size (0.1 degree minimum) and acquisition time (minimum 3 s) is set by the user.

Reliability Studies of Ceramic Capacitors.

DTIC Science & Technology

1983-07-01

increases. This case has been found to be a good approximation for single crystals with high chemical and structural purity. Shallow traps may arise as a...theory, this sudden increase may be otherwise explained. Single crystals of ZnS have been found to exhibit this vertical increase in the current...Smith and Rose observed SCLC behavior in CdS single crystals . Branwood and Tredgold 2 8 and Branwood et al. 2 9 measured BaTiO 3 single crystals and

Strong coupling in the optical spectra of polymorphs of a squarylium dye

NASA Astrophysics Data System (ADS)

Tristani-Kendra, M.; Eckhardt, C. J.; Bernstein, J.; Goldstein, E.

1983-06-01

The X-ray structure and single-crystal spectra of monoclinic and triclinic dimorphs of a squarylium dye are reported. Crystal polymorphism is shown to be an effective approach for studying excitation energy transfer in crystals. The long-axis-polarized transition leads to quasi-metallic reflection bands which cannot be fitted by molecular polariton calculations in the point-dipole approximation.

Vibrational and thermodynamic properties of β-HMX: a first-principles investigation.

PubMed

Wu, Zhongqing; Kalia, Rajiv K; Nakano, Aiichiro; Vashishta, Priya

2011-05-28

Thermodynamic properties of β-HMX crystal are investigated using the quasi-harmonic approximation and density functional theory within the local density approximation (LDA), generalized gradient approximation (GGA), and GGA + empirical van der Waals (vdW) correction. It is found that GGA well describes the thermal expansion coefficient and heat capacity but fails to produce correct bulk modulus and equilibrium volume. The vdW correction improves the bulk modulus and volume, but worsens the thermal expansion coefficient and heat capacity. In contrast, LDA describes all thermodynamic properties with reasonable accuracy, and overall is a good exchange-correlation functional for β-HMX molecular crystal. The results also demonstrate significant contributions of phonons to the equation of state. The static calculation of equilibrium volume for β-HMX differs from the room-temperature value incorporating lattice vibrations by over 5%. Therefore, for molecular crystals, it is essential to include phonon contributions when calculated equation of state is compared with experimental data at ambient condition. © 2011 American Institute of Physics

Laser ablation of dental tissues with picosecond pulses of 1.06-microm radiation transmitted through a hollow-core photonic-crystal fiber.

PubMed

Konorov, Stanislav O; Mitrokhin, Vladimir P; Fedotov, Andrei B; Sidorov-Biryukov, Dmitrii A; Beloglazov, Valentin I; Skibina, Nina B; Shcherbakov, Andrei V; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M

2004-04-10

Sequences of picosecond pulses of 1.06-microm Nd:YAG laser radiation with a total energy of approximately 2 mJ are transmitted through a hollow-core photonic-crystal fiber with a core diameter of approximately 14 microm and are focused onto a tooth's surface in vitro to ablate dental tissue. The hollow-core photonic-crystal fiber is shown to support the single-fundamental-mode regime for 1.06-microm laser radiation, serving as a spatial filter and allowing the laser beam's quality to be substantially improved. The same fiber is used to transmit emission from plasmas produced by laser pulses onto the tooth's surface in the backward direction for detection and optical diagnostics.

Enzyme Triggered Drug Delivery for Graft Targeted Immunosupression and Neuroregeneration after VCA

DTIC Science & Technology

2016-05-11

statement for research Involving animals . as required by AFMAN 40-401_1P : "The ClJCporiments reported herein were conducted according to the principles...sol forth In the National Institute of Health Publication No. 80-23, Gulde for the Care and Use of Laboratory Animals and tho Animal Welfare Act of...Cindass 0-3 59MDW ST RESTOR e. Kevin Wu CTR 59MDW ST RESTOR f. Michael R Davis 0-5 59MDW ST R ESTOR I CERTIFY ANY HUMAN OR ANIMAL RESEARCH RELATED

The Johns Hopkins RTR Consortium: A Collaborative Approach to Advance Translational Science and Standardize Clinical Monitoring of Restorative Transplantation - Immunomodulation and Tolerance Induction after VCA using Biologic Agent (cTLA4-Ig) and Donor Bone Marrow Cells

DTIC Science & Technology

2014-10-01

group, Pig 22227, was due to a gastrointestinal bleed , related to either infectious gastroenteritis/colitis or stress ulcer formation. The third... upper extremity transplantation. Delays in progress and incomplete groups will be discussed in detail in Section 5 – Changes/Problems. Table 1...Implemented successfully first clinical protocol for upper extremity transplantation using donor bone marrow cell therapies and tacrolimus

False Positive Immunoglobulin M Antibody to Cytomegalovirus in Child with Infectious Mononucleosis Caused by Epstein-Barr Virus Infection

PubMed Central

Shin, Jae Il; Lee, Jae Seung; Jang, Young Ho; Kim, Sung Hun; Lee, Kang Hyuk; Lee, Chang Hoon

2009-01-01

A 16-month-old boy was admitted because of cough that had lasted for 10 days. The patient showed severe hepatomegaly incidentally, and dual positivity of Immunoglobulin (Ig) M to Epstein-Barr virus (EBV) viral capsid antigen (VCA) and cytomegalovirus (CMV). On the basis of seroconversion to Epstein-Barr nuclear antigen (EBNA) Ig G positivity and reduced CMV Ig M titer with persistently negative CMV Ig G, a definite diagnosis of EBV-induced infectious mononucleosis was established 1 year 2 month later. PMID:19881978

Ex Vivo Machine Perfusion in VCA with a Novel Oxygen Carrier System to Enhance Graft Preservation and Immunologic Outcomes

DTIC Science & Technology

2016-12-01

studies 2. Ex Vivo Study Group (n=4) Machine Perfusion 4 VRAM grafts preserved for 14 hours with MP at 21°C Study group – developments for machine...period. The VRAM grafts were inspected daily and punch biopsies were performed on days 2, 4 and 7. The end- study necropsy was conducted on post ...TNF- α in the MP group, showing the beneficial impact of effective ex -vivo oxygenation in this group (Figure 6). Previous clinical studies in

False positive immunoglobulin m antibody to cytomegalovirus in child with infectious mononucleosis caused by epstein-barr virus infection.

PubMed

Park, Jee Min; Shin, Jae Il; Lee, Jae Seung; Jang, Young Ho; Kim, Sung Hun; Lee, Kang Hyuk; Lee, Chang Hoon

2009-10-31

A 16-month-old boy was admitted because of cough that had lasted for 10 days. The patient showed severe hepatomegaly incidentally, and dual positivity of Immunoglobulin (Ig) M to Epstein-Barr virus (EBV) viral capsid antigen (VCA) and cytomegalovirus (CMV). On the basis of seroconversion to Epstein-Barr nuclear antigen (EBNA) Ig G positivity and reduced CMV Ig M titer with persistently negative CMV Ig G, a definite diagnosis of EBV-induced infectious mononucleosis was established 1 year 2 month later.

Competition between monomeric and dimeric crystals in schematic models for globular proteins.

PubMed

Fusco, Diana; Charbonneau, Patrick

2014-07-17

Advances in experimental techniques and in theoretical models have improved our understanding of protein crystallization. However, they have also left open questions regarding the protein phase behavior and self-assembly kinetics, such as why (nearly) identical crystallization conditions can sometimes result in the formation of different crystal forms. Here, we develop a patchy particle model with competing sets of patches that provides a microscopic explanation of this phenomenon. We identify different regimes in which one or two crystal forms can coexist with a low-density fluid. Using analytical approximations, we extend our findings to different crystal phases, providing a general framework for treating protein crystallization when multiple crystal forms compete. Our results also suggest different experimental routes for targeting a specific crystal form, and for reducing the dynamical competition between the two forms, thus facilitating protein crystal assembly.

Light scattering by nonspherical particles: Remote sensing and climatic implications

NASA Astrophysics Data System (ADS)

Liou, K. N.; Takano, Y.

Calculations of the scattering and adsorption properties of ice crystals and aerosols, which are usually nonspherical, require specific methodologies. There is no unique theoretical solution for the scattering by nonspherical particles. Practically, all the numerical solutions for the scattering of nonspherical particles, including the exact wave equation approach, integral equation method, and discrete-dipole approximation, are applicable only to size parameters less than about 20. Thus, these methods are useful for the study of radiation problems involving nonspherical aerosols and small ice crystals in the thermal infrared wavelengths. The geometric optics approximation has been used to evaluate the scattering, absorption and polarization properties of hexagonal ice crystals whose sizes are much larger than the incident wavelength. This approximation is generally valid for hexagonal ice crystals with size parameters larger than about 30. From existing laboratory data and theoretical results, we illustrate that nonspherical particles absorb less and have a smaller asymmetry factor than the equal-projected area/volume spherical counterparts. In particular, we show that hexagonal ice crystals exhibit numerous halo and arc features that cannot be obtained from spherical particles; and that ice crystals scatter more light in the 60° to 140° scattering angle regions than the spherical counterparts. Satellite remote sensing of the optical depth and height of cirrus clouds using visible and IR channels must use appropriate phase functions for ice crystals. Use of an equivalent sphere model would lead to a significant overestimation and underestimation of the cirrus optical depth and height, respectively. Interpretation of the measurements for polarization reflected from sunlight involving cirrus clouds cannot be made without an appropriate ice crystal model. Large deviations exist for the polarization patterns between spheres and hexagonal ice crystals. Interpretation of lidar backscattering and depolarization signals must also utilize the scattering characteristics of hexagonal ice crystals. Equivalent spherical models substantially underestimate the broadband solar albedos of ice crystal clouds because of stronger forward scattering and larger absorption by spherical particles than hexagonal ice crystals. We illustrate that the net cloud radiative forcing at the top of the atmosphere involving most cirrus clouds is positive, implying that the IR greenhouse effect outweighs the solar albedo effect. If the radiative properties of equivalent spheres are used, a significant increase in cloud radiative forcing occurs. Using a one-dimensional cloud and climate model, we further demonstrate that there is sufficient model sensitivity, in terms of temperature increase, to the use of ice crystal models in radiation calculations.

A spatially resolving x-ray crystal spectrometer for measurement of ion-temperature and rotation-velocity profiles on the Alcator C-Mod tokamak.

PubMed

Hill, K W; Bitter, M L; Scott, S D; Ince-Cushman, A; Reinke, M; Rice, J E; Beiersdorfer, P; Gu, M-F; Lee, S G; Broennimann, Ch; Eikenberry, E F

2008-10-01

A new spatially resolving x-ray crystal spectrometer capable of measuring continuous spatial profiles of high resolution spectra (lambda/d lambda>6000) of He-like and H-like Ar K alpha lines with good spatial (approximately 1 cm) and temporal (approximately 10 ms) resolutions has been installed on the Alcator C-Mod tokamak. Two spherically bent crystals image the spectra onto four two-dimensional Pilatus II pixel detectors. Tomographic inversion enables inference of local line emissivity, ion temperature (T(i)), and toroidal plasma rotation velocity (upsilon(phi)) from the line Doppler widths and shifts. The data analysis techniques, T(i) and upsilon(phi) profiles, analysis of fusion-neutron background, and predictions of performance on other tokamaks, including ITER, will be presented.

Crystallization of bFGF-DNA Aptamer Complexes Using a Sparse Matrix Designed for Protein-Nucleic Acid Complexes

NASA Technical Reports Server (NTRS)

Cannone, Jaime J.; Barnes, Cindy L.; Achari, Aniruddha; Kundrot, Craig E.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The Sparse Matrix approach for obtaining lead crystallization conditions has proven to be very fruitful for the crystallization of proteins and nucleic acids. Here we report a Sparse Matrix developed specifically for the crystallization of protein-DNA complexes. This method is rapid and economical, typically requiring 2.5 mg of complex to test 48 conditions. The method was originally developed to crystallize basic fibroblast growth factor (bFGF) complexed with DNA sequences identified through in vitro selection, or SELEX, methods. Two DNA aptamers that bind with approximately nanomolar affinity and inhibit the angiogenic properties of bFGF were selected for co-crystallization. The Sparse Matrix produced lead crystallization conditions for both bFGF-DNA complexes.

Mathematical modeling and statistical analysis of SPE-OCDMA systems utilizing second harmonic generation effect in thick crystal receivers

NASA Astrophysics Data System (ADS)

Matinfar, Mehdi D.; Salehi, Jawad A.

2009-11-01

In this paper we analytically study and evaluate the performance of a Spectral-Phase-Encoded Optical CDMA system for different parameters such as the user's code length and the number of users in the network. In this system an advanced receiver structure in which the Second Harmonic Generation effect imposed in a thick crystal is employed as the nonlinear pre-processor prior to the conventional low speed photodetector. We consider ASE noise of the optical amplifiers, effective in low power conditions, besides the multiple access interference (MAI) noise which is the dominant source of noise in any OCDMA communications system. We use the results of the previous work which we analyzed the statistical behavior of the thick crystals in an optically amplified digital lightwave communication system to evaluate the performance of the SPE-OCDMA system with thick crystals receiver structure. The error probability is evaluated using Saddle-Point approximation and the approximation is verified by Monte-Carlo simulation.

One-dimensional dielectric bi-periodic photonic structures based on ternary photonic crystals

NASA Astrophysics Data System (ADS)

Dadoenkova, Nataliya N.; Dadoenkova, Yuliya S.; Panyaev, Ivan S.; Sannikov, Dmitry G.; Lyubchanskii, Igor L.

2018-01-01

We investigate the transmittivity spectra, fields, and energy distribution of the electromagnetic eigenwaves propagating in a one-dimensional (1D) dielectric photonic crystal [(TiO2/SiO2)NAl2O3]M with two periods formed by unit cells TiO2/SiO2 and (TiO2/SiO2)NAl2O3. Spectra of TE- and TM-modes depend on the geometric parameters of the structure and undergo modifications with the change in the period numbers, layer thicknesses, and incidence angle. Special attention is paid to the applicability of the hybrid effective medium approximation comprising the long-wave approximation and two-dimensional (2 × 2) transfer matrix method. We demonstrate spectral peculiarities of the bi-periodic structure and also show the differences between the band gap spectra of the bi-periodic and ternary 1D dielectric photonic crystals. The presented photonic crystal structure can find its applications in optoelectronics and nanophotonics areas as omnidirectional reflectors, optical ultra-narrow bandpass filters, and antireflection coatings.

Estimating ice particle scattering properties using a modified Rayleigh-Gans approximation

NASA Astrophysics Data System (ADS)

Lu, Yinghui; Clothiaux, Eugene E.; Aydin, Kültegin; Verlinde, Johannes

2014-09-01

A modification to the Rayleigh-Gans approximation is made that includes self-interactions between different parts of an ice crystal, which both improves the accuracy of the Rayleigh-Gans approximation and extends its applicability to polarization-dependent parameters. This modified Rayleigh-Gans approximation is both efficient and reasonably accurate for particles with at least one dimension much smaller than the wavelength (e.g., dendrites at millimeter or longer wavelengths) or particles with sparse structures (e.g., low-density aggregates). Relative to the Generalized Multiparticle Mie method, backscattering reflectivities at horizontal transmit and receive polarization (HH) (ZHH) computed with this modified Rayleigh-Gans approach are about 3 dB more accurate than with the traditional Rayleigh-Gans approximation. For realistic particle size distributions and pristine ice crystals the modified Rayleigh-Gans approach agrees with the Generalized Multiparticle Mie method to within 0.5 dB for ZHH whereas for the polarimetric radar observables differential reflectivity (ZDR) and specific differential phase (KDP) agreement is generally within 0.7 dB and 13%, respectively. Compared to the A-DDA code, the modified Rayleigh-Gans approximation is several to tens of times faster if scattering properties for different incident angles and particle orientations are calculated. These accuracies and computational efficiencies are sufficient to make this modified Rayleigh-Gans approach a viable alternative to the Rayleigh-Gans approximation in some applications such as millimeter to centimeter wavelength radars and to other methods that assume simpler, less accurate shapes for ice crystals. This method should not be used on materials with dielectric properties much different from ice and on compact particles much larger than the wavelength.

Optical properties and refractive indices of Gd3Al2Ga3O12:Ce3+ crystals

NASA Astrophysics Data System (ADS)

Kozlova, N. S.; Busanov, O. A.; Zabelina, E. V.; Kozlova, A. P.; Kasimova, V. M.

2016-05-01

Crystals of cerium-doped gadolinium-gallium-aluminum garnet have been grown by the Czochralski method. The transmission and reflection spectra of these crystals in the wavelength range of 250-800 nm have been obtained by optical spectroscopy. Refractive indices are calculated based on the measured Brewster angles, the experimental results are approximated using the Cauchy equation, and a dispersion dependence is obtained.

Purification, crystallization and preliminary X-ray analysis of Enterococcus faecium aminoglycoside-2′′-phosphotransferase-Ib [APH(2′′)-Ib

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walanj, Rupa; Young, Paul; Baker, Heather M.

2005-04-01

APH(2′′)-Ib is an enzyme responsible for high-level gentamicin resistance in E. faecium isolates. Native crystals of this enzyme have been prepared and preliminary X-ray diffraction experiments have been undertaken. Bacterial resistance to the aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, APH(2′′)-Ib, has been cloned and the protein (comprising 299 amino-acid residues) expressed in Escherichia coli, purified and crystallized in the presence of 16%(w/v) PEG 3350 and gentamicin. The crystals belong tomore » the monoclinic space group P2{sub 1}, with approximate unit-cell parameters a = 79.7, b = 58.8, c = 81.4 Å, β = 98.4°, and preliminary X-ray diffraction analysis is consistent with the presence of two molecules in the asymmetric unit. Synchrotron diffraction data to approximately 2.65 Å resolution were collected from a native APH(2′′)-Ib crystal at beamline BL9-2 at SSRL (Stanford, CA, USA). Selenium-substituted crystals have also been produced and structure determination is proceeding.« less

On thermal conditions and properties of thallium bromide single crystals grown by the Electro Dynamic Gradient method

NASA Astrophysics Data System (ADS)

Zheng, Zhiping; Yu, Yongtao; Gong, Shuping; Fu, Qiuyun; Zhou, Dongxiang

2013-05-01

The Electro Dynamic Gradient (EDG) method has been proved to be a feasible way to grow TlBr crystals in our previous work. In this research, the influence of thermal conditions such as cooling rate during growth process on the crystal performance was investigated. Crystals of approximately 12 mm diameter were obtained by the EDG method at different cooling rates during the growth process, and the quality of the crystals was routinely evaluated by X-ray diffraction (XRD), infrared (IR) and ultraviolet (UV) transmission, I-V measurement and energy response spectrum. The results proved that thermal conditions during growth had a profound influence on the characteristics of the crystals.

Secretome Analysis of Vibrio cholerae Type VI Secretion System Reveals a New Effector-Immunity Pair

PubMed Central

Altindis, Emrah; Dong, Tao; Catalano, Christy

2015-01-01

ABSTRACT The type VI secretion system (T6SS) is a dynamic macromolecular organelle that many Gram-negative bacteria use to inhibit or kill other prokaryotic or eukaryotic cells. The toxic effectors of T6SS are delivered to the prey cells in a contact-dependent manner. In Vibrio cholerae, the etiologic agent of cholera, T6SS is active during intestinal infection. Here, we describe the use of comparative proteomics coupled with bioinformatics to identify a new T6SS effector-immunity pair. This analysis was able to identify all previously identified secreted substrates of T6SS except PAAR (proline, alanine, alanine, arginine) motif-containing proteins. Additionally, this approach led to the identification of a new secreted protein encoded by VCA0285 (TseH) that carries a predicted hydrolase domain. We confirmed that TseH is toxic when expressed in the periplasm of Escherichia coli and V. cholerae cells. The toxicity observed in V. cholerae was suppressed by coexpression of the protein encoded by VCA0286 (TsiH), indicating that this protein is the cognate immunity protein of TseH. Furthermore, exogenous addition of purified recombinant TseH to permeabilized E. coli cells caused cell lysis. Bioinformatics analysis of the TseH protein sequence suggest that it is a member of a new family of cell wall-degrading enzymes that include proteins belonging to the YD repeat and Rhs superfamilies and that orthologs of TseH are likely expressed by species belonging to phyla as diverse as Bacteroidetes and Proteobacteria. PMID:25759499

True morphology of mitral regurgitant flow assessed by three-dimensional transesophageal echocardiography.

PubMed

Lombardero, Martin; Henquin, Ruth; Perea, Gabriel; Corneli, Mariana; Izurieta, Carlos

2017-01-01

Quantification of mitral regurgitation (MR) by two-dimensional (2D) transthoracic echocardiography (TTE) is based on the analysis of the proximal flow convergence (PFC) and the "vena contracta" (VC). This method assumes geometries and can be misleading. In contrast, three-dimensional (3D) echocardiography directly measures flow volumes and does not assume geometries, which allows for more accurate MR evaluation. To report the 3D transesophageal echocardiography (3DTEE) feasibility for MR quantification and evaluate its concordance with 2D echo. Twenty-seven consecutive patients undergoing 2D and 3DTEE for presurgical MR evaluation were studied prospectively. MR quantification was performed by classical 2D methods based on PFC. Diameters of the VC in orthogonal planes by 3DTEE were estimated, establishing the VC sphericity index as well as VC area (VCA) by direct planimetry. In case of multiple jets, we calculated the sum of the VCA. MR assessment by 3DTEE was feasible. An adequate concordance between VC measurements by 2D methods (TTE and TEE) was observed; however, there was a poor correlation when compared with 3DTEE. The sphericity index of the VC was: 2.08 (±0. 72), reflecting a noncircular VC. 3DTEE is a feasible method for the assessment of the MR true morphology, allowing a better quantification of MR without assuming any geometry. This method revealed the presence of multiple jets, potentially improving MR evaluation and leading to changes in medical decision when compared to 2D echo assessment. © 2016, Wiley Periodicals, Inc.

Design of a prototype position actuator for the primary mirror segments of the European Extremely Large Telescope

NASA Astrophysics Data System (ADS)

Jiménez, A.; Morante, E.; Viera, T.; Núñez, M.; Reyes, M.

2010-07-01

European Extremely Large Telescope (E-ELT) based in 984 primary mirror segments achieving required optical performance; they must position relatively to adjacent segments with relative nanometer accuracy. CESA designed M1 Position Actuators (PACT) to comply with demanding performance requirements of EELT. Three PACT are located under each segment controlling three out of the plane degrees of freedom (tip, tilt, piston). To achieve a high linear accuracy in long operational displacements, PACT uses two stages in series. First stage based on Voice Coil Actuator (VCA) to achieve high accuracies in very short travel ranges, while second stage based on Brushless DC Motor (BLDC) provides large stroke ranges and allows positioning the first stage closer to the demanded position. A BLDC motor is used achieving a continuous smoothly movement compared to sudden jumps of a stepper. A gear box attached to the motor allows a high reduction of power consumption and provides a great challenge for sizing. PACT space envelope was reduced by means of two flat springs fixed to VCA. Its main characteristic is a low linear axial stiffness. To achieve best performance for PACT, sensors have been included in both stages. A rotary encoder is included in BLDC stage to close position/velocity control loop. An incremental optical encoder measures PACT travel range with relative nanometer accuracy and used to close the position loop of the whole actuator movement. For this purpose, four different optical sensors with different gratings will be evaluated. Control strategy show different internal closed loops that work together to achieve required performance.

Targeting fibroblast growth factor receptor signaling inhibits prostate cancer progression.

PubMed

Feng, Shu; Shao, Longjiang; Yu, Wendong; Gavine, Paul; Ittmann, Michael

2012-07-15

Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo. Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model. AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors. Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.

Defining functional SMA and pre-SMA subregions in human MFC using resting state fMRI: functional connectivity-based parcellation method.

PubMed

Kim, Jae-Hun; Lee, Jong-Min; Jo, Hang Joon; Kim, Sook Hui; Lee, Jung Hee; Kim, Sung Tae; Seo, Sang Won; Cox, Robert W; Na, Duk L; Kim, Sun I; Saad, Ziad S

2010-02-01

Noninvasive parcellation of the human cerebral cortex is an important goal for understanding and examining brain functions. Recently, the patterns of anatomical connections using diffusion tensor imaging (DTI) have been used to parcellate brain regions. Here, we present a noninvasive parcellation approach that uses "functional fingerprints" obtained by correlation measures on resting state functional magnetic resonance imaging (fMRI) data to parcellate brain regions. In other terms, brain regions are parcellated based on the similarity of their connection--as reflected by correlation during resting state--to the whole brain. The proposed method was used to parcellate the medial frontal cortex (MFC) into supplementary motor areas (SMA) and pre-SMA subregions. In agreement with anatomical landmark-based parcellation, we find that functional fingerprint clustering of the MFC results in anterior and posterior clusters. The probabilistic maps from 12 subjects showed that the anterior cluster is mainly located rostral to the vertical commissure anterior (VCA) line, whereas the posterior cluster is mainly located caudal to VCA line, suggesting the homologues of pre-SMA and SMA. The functional connections from the putative pre-SMA cluster were connected to brain regions which are responsible for complex/cognitive motor control, whereas those from the putative SMA cluster were connected to brain regions which are related to the simple motor control. These findings demonstrate the feasibility of the functional connectivity-based parcellation of the human cerebral cortex using resting state fMRI. Copyright (c) 2009 Elsevier Inc. All rights reserved.

[Clinical and laboratory characteristics of chronic active Epstein-Barr virus infection in children].

PubMed

Mao, Jun-Qing; Yang, Shi-Long; Song, Hua; Zhao, Fen-Ying; Xu, Xiao-Jun; Gu, Min-Er; Tang, Yong-Min

2014-11-01

To study the clinical and laboratory characteristics of chronic active Epstein-Barr virus (EBV) infection (CAEBV) in children and to provide a basis for the diagnosis and treatment of CAEBV. The clinical data of 13 children with CAEBV, as well as 15 cases of acute EBV infection (AEBV) as controls, were analyzed, including clinical manifestations, EBV antibodies, EBV DNA, and peripheral blood lymphocyte subsets. Both groups of patients had infectious mononucleosis-like symptoms such as fever, hepatomegaly, splenomegaly, and lymphadenectasis, but CAEBV patients had a longer course of disease and continuous and recurrent symptoms. Compared with the AEBV group, the CAEBV group had a significantly higher EBV DNA load in peripheral blood (P<0.05), a significantly higher VCA-IgG titer (P<0.05), and significantly lower numbers of white blood cells, lymphocytes, B cells, total T cells, CD4+ T cells, and CD8+ T cells in peripheral blood (P<0.05). Among 13 CAEBV patients followed up, 8 cases died, 2 cases showed an improvement, 2 cases had a recurrence, and 1 case was lost to follow-up after being transferred to another hospital. All the AEBV patients were cured and had no recurrence during the one-year follow-up. The clinical manifestations of CAEBV vary in children. It is difficult to distinguish CAEBV from AEBV early. More attention should be paid to CAEBV because of its severe complications, poor prognosis, and high mortality. Measurement of EBV DNA load, VCA-IgG titer, and lymphocyte subsets in peripheral blood may be helpful in the diagnosis and differential diagnosis of CAEBV.

Histone deacetylase inhibitors, valproic acid and trichostatin-A induce apoptosis and affect acetylation status of p53 in ERG-positive prostate cancer cells

PubMed Central

FORTSON, WENDELL S.; KAYARTHODI, SHUBHALAXMI; FUJIMURA, YASUO; XU, HUALI; MATTHEWS, ROLAND; GRIZZLE, WILLIAM E.; RAO, VEENA N.; BHAT, GANAPATHY K.; REDDY, E. SHYAM P.

2012-01-01

An ETS family member, ETS Related Gene (ERG) is involved in the Ewing family of tumors as well as leukemias. Rearrangement of the ERG gene with the TMPRSS2 gene has been identified in the majority of prostate cancer patients. Additionally, overexpression of ERG is associated with un- favorable prognosis in prostate cancer patients similar to leukemia patients. Histone acetyltransferases (HATs) and histone deacetylases (HDACs) regulate transcription as well as epigenetic status of genes through acetylation of both histones and transcription factors. Deregulation of HATs and HDACs is frequently seen in various cancers, including prostate cancer. Many cellular oncogenes as well as tumor viral proteins are known to target either or both HATs and HDACs. Several studies have demonstrated that there are alterations of HDAC activity in prostate cancer cells. Recently, we found that ERG binds and inhibits HATs, which suggests that ERG is involved in deregulation of protein acetylation. Additionally, it has been shown that ERG is associated with a higher expression of HDACs. In this study, we tested the effect of the HDAC inhibitors valproic acid (VPA) and trichostatin-A (TSA) on ERG-positive prostate cancer cells (VCaP). We found that VPA and TSA induce apoptosis, upregulate p21/Waf1/CIP1, repress TMPRSS2-ERG expression and affect acetylation status of p53 in VCaP cells. These results suggest that HDAC inhibitors might restore HAT activity through two different ways: by inhibiting HDAC activity and by repressing HAT targeting oncoproteins such as ERG. PMID:21519790

Deficient EBV-specific B- and T-cell response in patients with chronic fatigue syndrome.

PubMed

Loebel, Madlen; Strohschein, Kristin; Giannini, Carolin; Koelsch, Uwe; Bauer, Sandra; Doebis, Cornelia; Thomas, Sybill; Unterwalder, Nadine; von Baehr, Volker; Reinke, Petra; Knops, Michael; Hanitsch, Leif G; Meisel, Christian; Volk, Hans-Dieter; Scheibenbogen, Carmen

2014-01-01

Epstein-Barr virus (EBV) has long been discussed as a possible cause or trigger of Chronic Fatigue Syndrome (CFS). In a subset of patients the disease starts with infectious mononucleosis and both enhanced and diminished EBV-specific antibody titers have been reported. In this study, we comprehensively analyzed the EBV-specific memory B- and T-cell response in patients with CFS. While we observed no difference in viral capsid antigen (VCA)-IgG antibodies, EBV nuclear antigen (EBNA)-IgG titers were low or absent in 10% of CFS patients. Remarkably, when analyzing the EBV-specific memory B-cell reservoir in vitro a diminished or absent number of EBNA-1- and VCA-antibody secreting cells was found in up to 76% of patients. Moreover, the ex vivo EBV-induced secretion of TNF-α and IFN-γ was significantly lower in patients. Multicolor flow cytometry revealed that the frequencies of EBNA-1-specific triple TNF-α/IFN-γ/IL-2 producing CD4(+) and CD8(+) T-cell subsets were significantly diminished whereas no difference could be detected for HCMV-specific T-cell responses. When comparing EBV load in blood immune cells, we found more frequently EBER-DNA but not BZLF-1 RNA in CFS patients compared to healthy controls suggesting more frequent latent replication. Taken together, our findings give evidence for a deficient EBV-specific B- and T-cell memory response in CFS patients and suggest an impaired ability to control early steps of EBV reactivation. In addition the diminished EBV response might be suitable to develop diagnostic marker in CFS.

Epstein-Barr virus nuclear antigen-2 detection and typing in immunocompromised children correlated with lymphoproliferative disorder biopsy findings.

PubMed

Mendes, Thiago Marques; Oliveira, Léa Campos de; Yamamoto, Lídia; Del Negro, Gilda Maria Barbaro; Okay, Thelma Suely

2008-06-01

Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, plays a significant role as a cofactor in the process of tumorigenesis, and has consistently been associated with a variety of malignancies especially in immunocompromised patients. Forty-four children and adolescents (21 liver transplant patients, 7 heart transplant, 5 AIDS, 3 autoimmune hepatitis, 2 nephritic syndromes, 2 medullar aplasia, 2 primary immunodeficiency disorder patients, 1 thrombocytopenic purpura and 1 systemic lupus erythematosus) presenting with chronic active EBV infection (VCA-IgM persistently positive; VCA-IgG > 20 AU/mL and positive IgG _ EBNA) had peripheral blood samples obtained during clinically characterized EBV reactivation episodes. DNA samples were amplified in order to detect and type EBV on the basis of the EBNA-2 sequence (EBNA2 protein is essential for EBV-driven immortalization of B lymphocytes). Although we have found a predominance of type 1 EBNA-2 virus (33/44; 75%), 10 patients (22.73%) carried type 2 EBNA-2, and one liver transplant patient (2.27%) a mixture of the two types, the higher proportion of type 2 EBV, as well as the finding of one patient bearing the two types is in agreement with other reports held on lymphoproliferative disorder (LPD) patients, which analyzed tumor biopsies. We conclude that EBNA-2 detection and typing can be performed in peripheral blood samples, and the high prevalence of type 2 in our casuistic indicates that this population is actually at risk of developing LPD, and should be monitored.

A novel role for WAVE1 in controlling actin network growth rate and architecture.

PubMed

Sweeney, Meredith O; Collins, Agnieszka; Padrick, Shae B; Goode, Bruce L

2015-02-01

Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 ("V") domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2. © 2015 Sweeney et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Spatially resolved micro-Raman observation on the phase separation of effloresced sea salt droplets.

PubMed

Xiao, Han-Shuang; Dong, Jin-Ling; Wang, Liang-Yu; Zhao, Li-Jun; Wang, Feng; Zhang, Yun-Hong

2008-12-01

We report on the investigation of the phase separation of individual seawater droplets in the efflorescence processes with the spatially resolved Raman system. Upon decreasing the relative humidity (RH), CaSO4.0.5H2O separated out foremost fromthe droplet atan unexpectedly high RH of approcimately 90%. Occasionally, CaSO4.2H2O substituted for CaSO4.O.5H2O crystallizing first at approximately 78% RH. Relatively large NaCI solids followed to crystallize at approximately 55% RH and led to the great loss of the solution. Then, the KMgCl3.6H2O crystallites separated out from the residual solutions, adjacentto NaCl at approximately 44% RH. Moreover, a shell structure of dried sea salt particle was found to form at low RHs, with the NaCl crystals in the core and minor supersaturated solutions covered with MgSO4 gel coating on the surface. Ultimately, the shielded solution partly effloresced into MgSO4 hydrates at very dry state (<5% RH).

Modeling Conformal Growth in Photonic Crystals and Comparing to Experiment

NASA Astrophysics Data System (ADS)

Brzezinski, Andrew; Chen, Ying-Chieh; Wiltzius, Pierre; Braun, Paul

2008-03-01

Conformal growth, e.g. atomic layer deposition (ALD), of materials such as silicon and TiO2 on three dimensional (3D) templates is important for making photonic crystals. However, reliable calculations of optical properties as a function of the conformal growth, such as the optical band structure, are hampered by difficultly in accurately assessing a deposited material's spatial distribution. A widely used approximation ignores ``pinch off'' of precursor gas and assumes complete template infilling. Another approximation results in non-uniform growth velocity by employing iso-intensity surfaces of the 3D interference pattern used to create the template. We have developed an accurate model of conformal growth in arbitrary 3D periodic structures, allowing for arbitrary surface orientation. Results are compared with the above approximations and with experimentally fabricated photonic crystals. We use an SU8 polymer template created by 4-beam interference lithography, onto which various amounts of TiO2 are grown by ALD. Characterization is performed by analysis of cross-sectional scanning electron micrographs and by solid angle resolved optical spectroscopy.

Crystallization Kinetics of Amorphous AgInS2 Film

NASA Astrophysics Data System (ADS)

Kerimova, N. K.; Mamedova, A. Ch.

2018-04-01

The paper deals with crystallization kinetics of amorphous AgInS2 film. The dependence between lnln(V0 / (V0 -Vt) and lnt is obtained for 423, 448 and 468 K temperatures, which shows a linear arrangement of points for these temperatures, i.e. 2.80 2.87 and 2.93, respectively. The approximate equality of these values indicates that during AgInS2 film crystallization, a two-dimensional crystal growth occurs and the reaction rate constant equals (1/3π) {η}_n{η}_c^2.

Image transfer by cascaded stack of photonic crystal and air layers.

PubMed

Shen, C; Michielsen, K; De Raedt, H

2006-01-23

We demonstrate image transfer by a cascaded stack consisting of two and three triangular-lattice photonic crystal slabs separated by air. The quality of the image transfered by the stack is sensitive to the air/photonic crystal interface termination and the frequency. Depending on the frequency and the surface termination, the image can be transfered by the stack with very little deterioration of the resolution, that is the resolution of the final image is approximately the same as the resolution of the image formed behind one single photonic crystal slab.

A novel polyamine allosteric site of SpeG from Vibrio cholerae is revealed by its dodecameric structure

PubMed Central

Filippova, Ekaterina V.; Kuhn, Misty L.; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Ballicora, Miguel A.

2015-01-01

Spermidine N-acetyltransferase, encoded by the gene speG, catalyzes the initial step in the degradation of polyamines and is a critical enzyme for determining the polyamine concentrations in bacteria. In Escherichia coli, studies have shown that SpeG is the enzyme responsible for acetylating spermidine under stress conditions and for preventing spermidine toxicity. Not all bacteria contain speG, and many bacterial pathogens have developed strategies to either acquire or silence it for pathogenesis. Here, we present thorough kinetic analyses combined with structural characterization of the VCA0947 SpeG enzyme from the important human pathogen Vibrio cholerae. Our studies revealed the unexpected presence of a previously unknown allosteric site and an unusual dodecameric structure for a member of the Gcn5-related N-acetyltransferase (GNAT) superfamily. We show that SpeG forms dodecamers in solution and in crystals and describe its three-dimensional structure in several ligand-free and liganded structures. Importantly, these structural data define the first view of a polyamine bound in an allosteric site of an N-acetyltransferase. Kinetic characterization of SpeG from V. cholerae showed that it acetylates spermidine and spermine. The behavior of this enzyme is complex and exhibits sigmoidal curves and substrate inhibition. We performed a detailed non-linear regression kinetic analysis to simultaneously fit families of substrate saturation curves to uncover a simple kinetic mechanism that explains the apparent complexity of this enzyme. Our results provide a fundamental understanding of the bacterial SpeG enzyme, which will be key towards understanding the regulation of polyamine levels in bacteria during pathogenesis. PMID:25623305

Lidar inelastic multiple-scattering parameters of cirrus particle ensembles determined with geometrical-optics crystal phase functions.

PubMed

Reichardt, J; Hess, M; Macke, A

2000-04-20

Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height-independent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided.

From molecule to solid: The prediction of organic crystal structures

NASA Astrophysics Data System (ADS)

Dzyabchenko, A. V.

2008-10-01

A method for predicting the structure of a molecular crystal based on the systematic search for a global potential energy minimum is considered. The method takes into account unequal occurrences of the structural classes of organic crystals and symmetry of the multidimensional configuration space. The programs of global minimization PMC, comparison of crystal structures CRYCOM, and approximation to the distributions of the electrostatic potentials of molecules FitMEP are presented as tools for numerically solving the problem. Examples of predicted structures substantiated experimentally and the experience of author’s participation in international tests of crystal structure prediction organized by the Cambridge Crystallographic Data Center (Cambridge, UK) are considered.

Effects of Ultrasonic Parameters on the Crystallization Behavior of Virgin Coconut Oil.

PubMed

Wu, Linhe; Cao, Jun; Bai, Xinpeng; Chen, Haiming; Zhang, Yuxiang; Wu, Qian

2016-12-01

Crystallization behavior of virgin coconut oil (VCO) in the absence and presence of ultrasonic treatment under a temperature gradient field was investigated. The effects of ultrasonic parameters on the crystallization behavior of VCO were studied by differential scanning calorimetry, ultraviolet/visible spectrophotometry and polarized light microscopy. The thermal effect of the ultrasonic treatment was also increased at higher power levels. Therefore, the optimal power level was determined at approximately 36 W. Induction time reduced evidently and the crystallization rate was accelerated under ultrasonic treatment at crystallization temperature (T c ) above 15°C. However, no significant difference in induction time was noted at 13°C. The result of morphological studies showed that the growth mechanism of crystals was significantly changed. Meanwhile, smaller and uniform crystals were produced by the ultrasonic treatment. This study shows a novel technique to accelerate the crystallization rate and alter the growth mechanism of VCO crystals.

Progress in linear optics, non-linear optics and surface alignment of liquid crystals

NASA Astrophysics Data System (ADS)

Ong, H. L.; Meyer, R. B.; Hurd, A. J.; Karn, A. J.; Arakelian, S. M.; Shen, Y. R.; Sanda, P. N.; Dove, D. B.; Jansen, S. A.; Hoffmann, R.

We first discuss the progress in linear optics, in particular, the formulation and application of geometrical-optics approximation and its generalization. We then discuss the progress in non-linear optics, in particular, the enhancement of a first-order Freedericksz transition and intrinsic optical bistability in homeotropic and parallel oriented nematic liquid crystal cells. Finally, we discuss the liquid crystal alignment and surface effects on field-induced Freedericksz transition.

Focusing of light by polymer-dispersed liquid-crystal films with nanosized droplets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.

2006-12-15

An analysis is presented of polarization-independent electrically tunable light focusing by polymerdispersed liquid-crystal films with nanosized liquid-crystal droplets. Polymer-dispersed liquid-crystal films with axially symmetric distributions of liquid-crystal droplet concentration and layers with axially symmetric thickness profiles are considered. The paraxial, Rayleigh, and Rayleigh-Gans approximations, as well as the Foldy-Twersky equation, are used to examine the dependence of focal length on lens geometry, droplet size, concentration of nematic liquid-crystal droplets, and applied field. The tunable focusing ranges are evaluated for both lens types considered in the study. Dependence of the transmittance of polymer-dispersed liquid-crystal film on its characteristics is analyzed. Themore » results obtained are compared with those available from the literature.« less

A molecular-field approximation for quantum crystals. Ph.D. Thesis; [considering ground state properties

NASA Technical Reports Server (NTRS)

Danilowicz, R.

1973-01-01

Ground-state properties of quantum crystals have received considerable attention from both theorists and experimentalists. The theoretical results have varied widely with the Monte Carlo calculations being the most successful. The molecular field approximation yields ground-state properties which agree closely with the Monte Carlo results. This approach evaluates the dynamical behavior of each pair of molecules in the molecular field of the other N-2 molecules. In addition to predicting ground-state properties that agree well with experiment, this approach yields data on the relative importance of interactions of different nearest neighbor pairs.

High-Temperature Crystal-Growth Cartridge Tubes Made by VPS

NASA Technical Reports Server (NTRS)

Holmes, Richard; O'Dell, Scott; McKechnie, Timothy; Power, Christopher

2008-01-01

Cartridge tubes for use in a crystal growth furnace at temperatures as high as 1,600 deg. C have been fabricated by vacuum plasma spraying (VPS). These cartridges consist mainly of an alloy of 60 weight percent molybdenum with 40 weight percent rhenium, made from molybdenum powder coated with rhenium. This alloy was selected because of its high melting temperature (approximately equal.2,550 C) and because of its excellent ductility at room temperature. These cartridges are intended to supplant tungsten/nickel-alloy cartridges, which cannot be used at temperatures above approximately equal 1,300 C.

Emulsifier-free emulsion polymerization produces highly charged, monodisperse particles for near infrared photonic crystals.

PubMed

Reese, Chad E; Asher, Sanford A

2002-04-01

We have developed emulsifier-free, emulsion polymerization recipes for the synthesis of highly charged, monodisperse latex particles of diameters between 500 and 1100 nm. These latexes consist of poly[styrene-(co-2-hydroxyethyl methacrylate)] spherical particles whose surfaces are functionalized with sulfate and carboxylic acid groups. These highly charged, monodisperse particles readily self-assemble into robust, three-dimensionally ordered crystalline colloidal array photonic crystals that Bragg diffract light in the near infrared spectral region. By altering the particle number density, the diffraction wavelength can be tuned from approximately 1000 to approximately 4000 nm.

The Band Structure of Polymers: Its Calculation and Interpretation. Part 2. Calculation.

ERIC Educational Resources Information Center

Duke, B. J.; O'Leary, Brian

1988-01-01

Details ab initio crystal orbital calculations using all-trans-polyethylene as a model. Describes calculations based on various forms of translational symmetry. Compares these calculations with ab initio molecular orbital calculations discussed in a preceding article. Discusses three major approximations made in the crystal case. (CW)

Purification, Crystallization, and Preliminary X-ray Analysis of Native Canavalin

NASA Technical Reports Server (NTRS)

Pusey, Marc; Dowell, Jennifer; Ng, Joseph; Gavira, Jose A.

2003-01-01

The protein canavalin is a 7S vicilin, from the Jack Bean, Canavalis ensfomis. Canavalin is described as a seed storage protein, an energy source for a developing seed, as no other known activity or function has been found. The protein was first isolated and crystallized by Sumner and Howell (J. Biol. Chem. 113, 607-610, 1936). Canavalin spontaneously crystallizes after proteolytic cleavage at neutral pH, which removes residues 1-46, 224-245, and 325-330 and produces peptides of approximately 25, 13, and 12 kDa. Preliminary gel filtration experiments indicated the presence of nucleic acid with the uncleaved protein. We developed a dual column procedure, ion exchange followed by hydroxy apatite chromatography, that effectively removes the nucleic acid and yields an essentially pure uncut canavalin preparation with an OD 280/260 ratio of approximately 1.9-2.0. Standard crystallization screens using this material gave a number of positive results having a common requirement for alcohols and Mg(2+) ion, with crystals typically appearing within a day or less. Optimization experiments to date have shown that we can obtain crystals from pH 6.5 to pH 8.2, using MPD from 5 to 20% and 0.05 to 0.2M Mg(2+) (sulfate or acetate). The crystals are of space group P2(sub 1)2(sub 1)2(sub 1), unit cell dimensions, and a complete data set to 1.5 Angstroms, resolution has now been collected at a synchrotron source. Most importantly, the crystals are not twinned, a persistent problem with the most commonly obtained rhombohedral form of proteolytically cleaved canavalin.

Anisotropic Laminar Piezocomposite Actuator Incorporating Machined PMN-PT Single Crystal Fibers

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Inman, Daniel J.; Lloyd, Justin M.; High, James W.

2006-01-01

The design, fabrication, and testing of a flexible, laminar, anisotropic piezoelectric composite actuator utilizing machined PMN-32%PT single crystal fibers is presented. The device consists of a layer of rectangular single crystal piezoelectric fibers in an epoxy matrix, packaged between interdigitated electrode polyimide films. Quasistatic free-strain measurements of the single crystal device are compared with measurements from geometrically identical specimens incorporating polycrystalline PZT-5A and PZT-5H piezoceramic fibers. Free-strain actuation of the single crystal actuator at low bipolar electric fields (+/- 250 V/mm) is approximately 400% greater than that of the baseline PZT-5A piezoceramic device, and 200% greater than that of the PZT-5H device. Free-strain actuation under high unipolar electric fields (0-4kV/mm) is approximately 200% of the PZT-5A baseline device, and 150% of the PZT-5H alternate piezoceramic device. Performance increases at low field are qualitatively consistent with predicted increases based on scaling the low-field d33 piezoelectric constants of the respective piezoelectric materials. High-field increases are much less than scaled d33 estimates, but appear consistent with high-field freestrain measurements reported for similar bulk single-crystal and piezoceramic compositions. Measurements of single crystal actuator capacitance and coupling coefficient are also provided. These properties were poorly predicted using scaled bulk material dielectric and coupling coefficient data. Rules-of-mixtures calculations of the effective elastic properties of the single crystal device and estimated actuation work energy densities are also presented. Results indicate longitudinal stiffnesses significantly lower (50% less) than either piezoceramic device. This suggests that single-crystal piezocomposite actuators will be best suited to low induced-stress, high strain and deflection applications.

Anisotropic Piezocomposite Actuator Incorporating Machined PMN-PT Single Crystal Fibers

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Inman, Daniel J.; Lloyd, Justin M.; High, James W.

2004-01-01

The design, fabrication, and testing of a flexible, planar, anisotropic piezoelectric composite actuator utilizing machined PMN-32%PT single crystal fibers is presented. The device consists of a layer of rectangular single crystal piezoelectric fibers in an epoxy matrix, packaged between interdigitated electrode polyimide films. Quasistatic free-strain measurements of the single crystal device are compared with measurements from geometrically identical specimens incorporating polycrystalline PZT-5A and PZT-5H piezoceramic fibers. Free-strain actuation of the single crystal actuator at low bipolar electric fields (+/- 250 V/mm) is approximately 400% greater than that of the baseline PZT-5A piezoceramic device, and 200% greater than that of the PZT-5H device. Free-strain actuation under high unipolar electric fields (0-4kV/mm) is approximately 200% of the PZT-5A baseline device, and 150% of the PZT-5H alternate piezoceramic device. Performance increases at low field are qualitatively consistent with predicted increases based on scaling the low-field d(sub 33) piezoelectric constants of the respective piezoelectric materials. High-field increases are much less than scaled d(sub 33) estimates, but appear consistent with high-field freestrain measurements reported for similar bulk single-crystal and piezoceramic compositions. Measurements of single crystal actuator capacitance and coupling coefficient are also provided. These properties were poorly predicted using scaled bulk material dielectric and coupling coefficient data. Rules-of-mixtures calculations of the effective elastic properties of the single crystal device and estimated actuation work energy densities are also presented. Results indicate longitudinal stiffnesses significantly lower (50% less) than either piezoceramic device. This suggests that single-crystal piezocomposite actuators will be best suited to low induced-stress, high strain and deflection applications.

[Isolated palsy of the hypoglossal nerve complicating infectious mononucleosis].

PubMed

Carra-Dallière, C; Mernes, R; Juntas-Morales, R

2011-01-01

Neurological complications of infectious mononucleosis are rare. Various disorders have been described: meningitis, encephalitis, peripheral neuropathy. Isolated cranial nerve palsy has rarely been reported. A 16-year-old man was admitted for isolated and unilateral hypoglossal nerve palsy, four weeks after infectious mononucleosis. Cerebral MRI, cerebrospinal fluid study and electromyography were normal. IgM anti-VCA were positive. Two months later, without treatment, the tongue had almost fully recovered. To the best of our knowledge, only seven cases of isolated palsy of the hypoglossal nerve complicating infectious mononucleosis have been previously reported. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Fluorescence in situ hybridization is superior for monitoring Epstein Barr viral load in infectious mononucleosis patients.

PubMed

Cao, Pengfei; Zhang, Meili; Wang, Wei; Dai, Yafei; Sai, Buqing; Sun, Jun; Wang, Lujuan; Wang, Fan; Li, Guiyuan; Xiang, Juanjuan

2017-05-03

Epstein Barr virus (EBV) plays a causal role in some diseases, including infectious mononucleosis, lymphoproliferative diseases and nasopharyngeal carcinoma. Detection of EBV infection has been shown to be a useful tool for diagnosing EBV-related diseases. In the present study, we compared the performance of molecular tests, including fluorescence in situ hybridization (FISH) and EBV real-time PCR, to those of serological assays for the detection of EBV infection. Thirty-eight patients with infectious mononucleosis (IM) were enrolled, of whom 31 were diagnosed with a mild type, and seven were diagnosed with IM with haemophagocytic lymphohistiocytosis and chronic active EBV infection. Twenty healthy controls were involved in the study. The atypical lymphocytes in peripheral blood were detected under a microscope and the percentage of positive cells was calculated. EBV DNA load in peripheral blood was detected using real-time PCR. The FISH assay was developed to detect the EBV genome from peripheral blood mononuclear cells (PBMC). Other diagnosis methods including the heterophil agglutination (HA) test and EBV-VCA-IgM test, to detect EBV were also compared. SPSS17.0 was used for statistical analysis. In all, 5-41% atypical lymphocytes were found among the PBMC in mild IM patients, whereas 8-51% atypical lymphocytes were found in IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients. There was no significant difference in the ratios of atypical lymphoma between patients of the different types. We observed that 71.2% of mild IM patients and 85.7% of IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients were positive for EBV-VCA-IgM. EBV-VCA-IgM was negative in all healthy control subjects. In addition, 67.1% of mild IM patients tested heterophile antibody positive, whereas 71.4% of IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection tested positive. EBV DNA detected using real-time PCR was observed in 89.5% of these IM patients. The EBV genome was detected by the FISH assay in 97.4% of the IM patients. The EB viral loads detected by FISH and real-time PCR increased with the severity of IM. The EBV genome was detected in almost all the PBMC of IM with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients. Molecular tests, including FISH and EBV real-time PCR, are more sensitive than serological assays for the detection of EBV infection. The FISH assay detecting EBV copies in unfractionated whole blood is preferable and superior to plasma real-time PCR in its reflection of the absolute viral burden circulating in the patients.

Imaging System For Measuring Macromolecule Crystal Growth Rates in Microgravity

NASA Technical Reports Server (NTRS)

Corder, Eric L.; Briscoe, Jeri

2004-01-01

In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, a team of scientists and engineers at NASA's Marshal Space Flight Center (MSFC) developed flight hardware capable of measuring the crystal growth rates of a population of crystals growing under the same conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of crystal over time, the hardware was named Delta-L. Delta-L consists of three sub assemblies: a fluid unit including a temperature-controlled growth cell, an imaging unit, and a control unit (consisting of a Data Acquisition and Control Unit (DACU), and a thermal control unit). Delta-L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station. This paper will describe the Delta-L imaging system. The Delta-L imaging system was designed to locate, resolve, and capture images of up to 10 individual crystals ranging in size from 10 to 500 microns with a point-to-point accuracy of +/- 2.0 microns within a quartz growth cell observation area of 20 mm x 10 mm x 1 mm. The optical imaging system is comprised of a video microscope camera mounted on computer controlled translation stages. The 3-axis translation stages and control units provide crewmembers the ability to search throughout the growth cell observation area for crystals forming in size of approximately 10 microns. Once the crewmember has selected ten crystals of interest, the growth of these crystals is tracked until the size reaches approximately 500 microns. In order to resolve these crystals an optical system with a magnification of 10X was designed. A black and white NTSC camera was utilized with a 20X microscope objective and a 0.5X custom designed relay lens with an inline light to meet the magnification requirement. The design allows a 500 pm crystal to be viewed in the vertical dimension on a standard NTSC monitor (4:3 aspect ratio). Images of the 10 crystals are collected periodically and stored in sets by the DACU.

Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: crystallization relative humidities and nucleation rates.

PubMed

Pant, Atul; Parsons, Matthew T; Bertram, Allan K

2006-07-20

Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is approximately 34.3% RH under atmospheric conditions.

Optical characterization of randomly microrough surfaces covered with very thin overlayers using effective medium approximation and Rayleigh-Rice theory

NASA Astrophysics Data System (ADS)

Ohlídal, Ivan; Vohánka, Jiří; Čermák, Martin; Franta, Daniel

2017-10-01

The modification of the effective medium approximation for randomly microrough surfaces covered by very thin overlayers based on inhomogeneous fictitious layers is formulated. The numerical analysis of this modification is performed using simulated ellipsometric data calculated using the Rayleigh-Rice theory. The system used to perform this numerical analysis consists of a randomly microrough silicon single crystal surface covered with a SiO2 overlayer. A comparison to the effective medium approximation based on homogeneous fictitious layers is carried out within this numerical analysis. For ellipsometry of the system mentioned above the possibilities and limitations of both the effective medium approximation approaches are discussed. The results obtained by means of the numerical analysis are confirmed by the ellipsometric characterization of two randomly microrough silicon single crystal substrates covered with native oxide overlayers. It is shown that the effective medium approximation approaches for this system exhibit strong deficiencies compared to the Rayleigh-Rice theory. The practical consequences implied by these results are presented. The results concerning the random microroughness are verified by means of measurements performed using atomic force microscopy.

European Scientific Notes. Volume 35. Number 1.

DTIC Science & Technology

1981-01-31

thermotropic polymers, primar- formed smectic phases. She also studied ily with aromatic polyesters. Dr. R.W. the orientation of liquid crystal ...booster synchrotron and Linac are switched studies of crystals where a very good off and the electrons are allowed to approximation to a point source...compounds in the temperature Cr in a MgO host crystal in magnetic range of 1 to 25 K and as a function of fields up to 2*S T at temperatures between

Microgravity

NASA Image and Video Library

2004-04-15

Comparison of Germanium Telluride (GeTe) Crystals grown on Earth (left) and in space (right) during the Skylab SL-3 mission. These crystals were grown using a vapor transport crystal growth method in the Multipurpose Electric Furnace System (MEFS). Crystals grown on earth are needles and platelettes with distorted surfaces and hollow growth habits. The length of the ground-based needle is approximately 2 mm and the average lenth of the platelets is 1 mm. The dull appearance of the Skylab crystals resulted from condensation of the transport agent during the long cooling period dictated by the Skylab furnace. In a dedicated process, this would be prevented by removing the ampoule from the furnace and quenching the vapor source.

Effect of intracrystalline water on longitudinal sound velocity in tetragonal hen-egg-white lysozyme crystals.

PubMed

Tachibana, M; Koizumi, H; Kojima, K

2004-05-01

Longitudinal sound velocity of tetragonal hen-egg-white (HEW) lysozyme crystals was measured during air drying by ultrasonic pulseecho method. The sound velocity increases with exposure to open air and approaches a constant value. The maximum value is approximately 2900 m/s that is about 1.6 times as much as that of original one before drying. In addition, the sound velocity clearly recovers to original one after immersing the dried crystal in solution. Therefore, the sound velocity in tetragonal HEW lysozyme crystals can be reversibly changed due to dehydration and rehydration. These changes in sound velocity are discussed in the light of water-mediated intramolecular and intermolecular interactions in the crystals.

Testing the Ginzburg-Landau approximation for three-flavor crystalline color superconductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mannarelli, Massimo; Sharma, Rishi; Rajagopal, Krishna

2006-06-01

It is an open challenge to analyze the crystalline color superconducting phases that may arise in cold dense, but not asymptotically dense, three-flavor quark matter. At present the only approximation within which it seems possible to compare the free energies of the myriad possible crystal structures is the Ginzburg-Landau approximation. Here, we test this approximation on a particularly simple 'crystal' structure in which there are only two condensates {approx}{delta}exp(iq{sub 2}{center_dot}r) and {approx}{delta}exp(iq{sub 3}{center_dot}r) whose position-space dependence is that of two plane waves with wave vectors q{sub 2} and q{sub 3} at arbitrary angles. For this case, we are able tomore » solve the mean-field gap equation without making a Ginzburg-Landau approximation. We find that the Ginzburg-Landau approximation works in the {delta}{yields}0 limit as expected, find that it correctly predicts that {delta} decreases with increasing angle between q{sub 2} and q{sub 3} meaning that the phase with q{sub 2} parallel q{sub 3} has the lowest free energy, and find that the Ginzburg-Landau approximation is conservative in the sense that it underestimates {delta} at all values of the angle between q{sub 2} and q{sub 3}.« less

Genarris: Random generation of molecular crystal structures and fast screening with a Harris approximation

NASA Astrophysics Data System (ADS)

Li, Xiayue; Curtis, Farren S.; Rose, Timothy; Schober, Christoph; Vazquez-Mayagoitia, Alvaro; Reuter, Karsten; Oberhofer, Harald; Marom, Noa

2018-06-01

We present Genarris, a Python package that performs configuration space screening for molecular crystals of rigid molecules by random sampling with physical constraints. For fast energy evaluations, Genarris employs a Harris approximation, whereby the total density of a molecular crystal is constructed via superposition of single molecule densities. Dispersion-inclusive density functional theory is then used for the Harris density without performing a self-consistency cycle. Genarris uses machine learning for clustering, based on a relative coordinate descriptor developed specifically for molecular crystals, which is shown to be robust in identifying packing motif similarity. In addition to random structure generation, Genarris offers three workflows based on different sequences of successive clustering and selection steps: the "Rigorous" workflow is an exhaustive exploration of the potential energy landscape, the "Energy" workflow produces a set of low energy structures, and the "Diverse" workflow produces a maximally diverse set of structures. The latter is recommended for generating initial populations for genetic algorithms. Here, the implementation of Genarris is reported and its application is demonstrated for three test cases.

Crystallization and preliminary X-ray analysis of a low density lipoprotein from human plasma.

PubMed

Prassl, R; Chapman, J M; Nigon, F; Sara, M; Eschenburg, S; Betzel, C; Saxena, A; Laggner, P

1996-11-15

Single crystals of human plasma low density lipoprotein (LDL), the major transport vehicle for cholesterol in blood, have been produced with a view to analysis of the three-dimensional structure by x-ray crystallography. Crystals with dimensions of approximately 200 x 100 x 50 microm have been reproducibly obtained from highly homogeneous LDL particle subspecies, isolated in the density ranges d = 1.0271-1. 0297 g/ml and d = 1.0297-1.0327 g/ml. Electron microscopic imaging of ultrathin-sectioned preparations of the crystals confirmed the existence of a regular, quasihexagonal arrangement of spherical particles of approximately 18 nm in diameter, thereby resembling the dimensions characteristic of LDL after dehydration and fixation. X-ray diffraction with synchrotron radiation under cryogenic conditions revealed the presence of well resolved diffraction spots, to a resolution of about 29 A. The diffraction patterns are indexed in terms of a triclinic lattice with unit cell dimensions of a = 16. 1 nm, b = 39.0 nm, c = 43.9 nm; alpha = 96.2 degrees, beta = 92.1 degrees, gamma = 102 degrees, and with space group P1.

Radiative Transfer and Satellite Remote Sensing of Cirrus Clouds Using FIRE-2-IFO Data

NASA Technical Reports Server (NTRS)

2000-01-01

Under the support of the NASA grant, we have developed a new geometric-optics model (GOM2) for the calculation of the single-scattering and polarization properties for arbitrarily oriented hexagonal ice crystals. From comparisons with the results computed by the finite difference time domain (FDTD) method, we show that the novel geometric-optics can be applied to the computation of the extinction cross section and single-scattering albedo for ice crystals with size parameters along the minimum dimension as small as approximately 6. We demonstrate that the present model converges to the conventional ray tracing method for large size parameters and produces single-scattering results close to those computed by the FDTD method for size parameters along the minimum dimension smaller than approximately 20. We demonstrate that neither the conventional geometric optics method nor the Lorenz-Mie theory can be used to approximate the scattering, absorption, and polarization features for hexagonal ice crystals with size parameters from approximately 5 to 20. On the satellite remote sensing algorithm development and validation, we have developed a numerical scheme to identify multilayer cirrus cloud systems using AVHRR data. We have applied this scheme to the satellite data collected over the FIRE-2-IFO area during nine overpasses within seven observation dates. Determination of the threshold values used in the detection scheme are based on statistical analyses of these satellite data.

Crystal structure and phase stability in Fe{sub 1{minus}x}Co{sub x} from AB initio theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soederlind, P.; Abrikosov, I.A.; James, P.

1996-06-01

For alloys between Fe and Co, their magnetic properties determine their structure. From the occupation of d states, a phase diagram is expected which depend largely on the spin polarization. A method more elaborate than canonical band models is used to calculate the spin moment and crystal structure energies. This method was the multisublattice generalization of the coherent potential approximation in conjunction with the Linear-Muffin-Tin-Orbital method in the atomic sphere approximation. To treat itinerant magnetism, the Vosko-Wilk-Nusair parameterization was used for the local spin density approximation. The fcc, bcc, and hcp phases were studied as completely random alloys, while themore » {alpha}{prime} phase for off-stoichiometries were considered as partially ordered. Results are compared with experiment and canonical band model.« less

Pseudo-transient heat transfer in vertical Bridgman crystal growth of semi-transparent materials

NASA Astrophysics Data System (ADS)

Barvinschi, F.; Nicoara, I.; Santailler, J. L.; Duffar, T.

1998-11-01

The temperature distribution and the solid-liquid interface shape during semi-transparent crystal growth have been studied by modelling a vertical Bridgman technique, using a pseudo-transient approximation in an ideal configuration. The heat transfer equation and the boundary conditions have been solved by the finite-element method. It has been pointed out that the optical absorption coefficients of the liquid and solid phases have a major effect on the thermal field, especially on the shape and location of the crystallization interface.

Vibrational, calorimetric and nonlinear optical studies of melaminium-bis(trichloroacetate) monohydrate molecular ionic crystal

NASA Astrophysics Data System (ADS)

Debrus, S.; Marchewka, M. K.; Drozd, M.; Ratajczak, H.

2007-04-01

The efficiency of second harmonic generation for melaminium bis(trichloroacetate) was estimated relatively to KDP: deff = 3.09 deff (KDP). Room temperature FT IR and FT Raman spectra were recorded. Some spectral features of this new crystal are referred to corresponding one for melamine crystal as well as for other trichloroacetates. Differential scanning calorimetric measurements performed on powder sample indicate the phase transition point at approximately 276 and 239 K for heating and cooling, respectively.

Evolution of the eukaryotic ARP2/3 activators of the WASP family: WASP, WAVE, WASH, and WHAMM, and the proposed new family members WAWH and WAML

PubMed Central

2012-01-01

Background WASP family proteins stimulate the actin-nucleating activity of the ARP2/3 complex. They include members of the well-known WASP and WAVE/Scar proteins, and the recently identified WASH and WHAMM proteins. WASP family proteins contain family specific N-terminal domains followed by proline-rich regions and C-terminal VCA domains that harbour the ARP2/3-activating regions. Results To reveal the evolution of ARP2/3 activation by WASP family proteins we performed a "holistic" analysis by manually assembling and annotating all homologs in most of the eukaryotic genomes available. We have identified two new families: the WAML proteins (WASP and MIM like), which combine the membrane-deforming and actin bundling functions of the IMD domains with the ARP2/3-activating VCA regions, and the WAWH protein (WASP without WH1 domain) that have been identified in amoebae, Apusozoa, and the anole lizard. Surprisingly, with one exception we did not identify any alternative splice forms for WASP family proteins, which is in strong contrast to other actin-binding proteins like Ena/VASP, MIM, or NHS proteins that share domains with WASP proteins. Conclusions Our analysis showed that the last common ancestor of the eukaryotes must have contained a homolog of WASP, WAVE, and WASH. Specific families have subsequently been lost in many taxa like the WASPs in plants, algae, Stramenopiles, and Euglenozoa, and the WASH proteins in fungi. The WHAMM proteins are metazoa specific and have most probably been invented by the Eumetazoa. The diversity of WASP family proteins has strongly been increased by many species- and taxon-specific gene duplications and multimerisations. All data is freely accessible via http://www.cymobase.org. PMID:22316129

Split Tolerance in a Murine Model of Heterotopic En Bloc Chest Wall Transplantation

PubMed Central

Oh, Byoungchol; Furtmüller, Georg J.; Malek, Veronika; Fryer, Madeline L.; Brayton, Cory; Walczak, Piotr; Janowski, Miroslaw

2017-01-01

Background: Congenital and acquired chest wall deformities represent a significant challenge to functional reconstruction and may impact feasibility of heart transplantation for patients with end-stage organ failure. In the recent past, the concept of replacing like-with-like tissue by using vascularized composite allografts (VCA) has been enthusiastically employed for reconstruction of complex tissue defects. Methods: In this study, we introduce a novel murine model for en bloc chest wall, heart, and thymus transplantation and thereby the use of complex tissue allografts for reconstruction of both chest wall defects and also end-stage organ failure. Additionally, this model allows us to study the features of combined vascularized bone marrow (VBM), thymus, and heart transplantation on allograft survival and function. Heterotopic chest wall, thymus, and heart transplants were performed in untreated syngeneic and allogeneic combinations and in allogeneic combinations treated with costimulation blockade (CTLA4-Ig and MR-1). Results: Indefinite (ie, 150 d, N = 3) graft survival was observed in syngeneic controls. In untreated recipients of allogeneic grafts, the skin component was rejected after 10 (±1) days, whereas rejection of the heart occurred after 13 (± 1) days (N = 3). Costimulation blockade treatment prolonged survival of the heart and chest wall component (130 d, N = 3) as well as the VBM niche as evidenced by donor-specific chimerism (average: 2.35 ± 1.44%), whereas interestingly, the skin component was rejected after 13 (±1) days. Conclusion: Thus, this novel microsurgical model of VCA combined with solid organ transplantation is technically feasible and results in split tolerance when treated with costimulatory blockade. PMID:29632774

Animal in vivo models of EBV-associated lymphoproliferative diseases: special references to rabbit models.

PubMed

Hayashi, K; Teramoto, N; Akagi, T

2002-10-01

Animal models of human EBV-associated diseases are essential to elucidate the pathogenesis of EBV-associated diseases. Here we review those previous models using EBV or EBV-like herpesviruses and describe the details on our two newly-developed rabbit models of lymphoproliferative diseases (LPD) induced by simian EBV-like viruses. The first is Cynomolgus-EBV-induced T-cell lymphomas in rabbits inoculated intravenously (77-90%) and orally (82-89%) during 2-5 months. EBV-DNA was detected in peripheral blood by PCR from 2 days after oral inoculation, while anti-EBV-VCA IgG was raised 3 weeks later. Rabbit lymphomas and their cell lines contained EBV-DNA and expressed EBV-encoded RNA-1 (EBER-1). Rabbit lymphoma cell lines, most of which have specific chromosomal abnormality, showed tumorigenicity in nude mice. The second is the first animal model for EBV-infected T-cell LPD with virus-associated hemophagocytic syndrome (VAHS), using rabbits infected with an EBV-like herpesvirus, Herpesvirus papio (HVP). Rabbits inoculated intravenously with HVP-producing cells showed increased anti-EBV-VCA-IgG titers, and most (85%) subsequently died of fatal LPD and VAHS, with bleeding and hepatosplenomegaly, during 22-105 days. Peroral spray of cell-free HVP induced viral infection with seroconversion in 3 out of 5 rabbits, with 2 of the 3 infected rabbits dying of LPD with VAHS. Atypical T lymphocytes containing HVP-DNA and expressing EBER-1 were observed in many organs. Hemophagocytic histiocytosis was observed in the lymph nodes, spleen, bone marrow, and thymus. These rabbit models are also useful and inexpensive alternative experimental model systems for studying the biology and pathogenesis of EBV, and prophylactic and therapeutic regimens.

Association Between Acute Infectious Mononucleosis and Vitamin D Deficiency.

PubMed

Maghzi, Helia; Ataei, Behrooz; Khorvash, Farzin; Yaran, Majid; Maghzi, Amir-Hadi

2016-09-01

Epstein-Barr virus and vitamin D both have been implicated in the pathogenesis of autoimmune diseases, especially multiple sclerosis (MS). Vitamin D influences both innate and adaptive immune responses and has been linked to increased susceptibility to other viral infections such as influenza. Here we aimed to examine the association between vitamin D and acute infectious mononucleosis (IM).This study is a case-control study that was conducted on IM patients and a control group of healthy individuals at infectious disease clinics of Isfahan University of Medical Sciences. Patients were recruited from January to December 2014. The viral capsid antigen (VCA) IgM titer and vitamin D levels were measured at the time of acute infection in IM patients. We also measured vitamin D levels in healthy controls recruited during the same period of time. A total number of 60 IM patients with the mean age of 23.26 ± 7.59 and a healthy control group with the mean age of 25.13 ± 6.72 were enrolled. In the IM patients, there was no significant association between 25(OH) D3 levels and VCA IgM titers (r = 0.190, p = 0.146). Mean 25(OH) D3 levels in IM patients were significantly lower than in the control group (15.61 ± 9.72 vs. 21.41 ± 12.64, p = 0.006). Our findings showed significantly lower vitamin D levels in IM patients at the time of infection than in the control group, providing some evidence that the two major risk factors for autoimmune diseases (e.g., MS) might not be independent risk factors.

Abhydrolase domain containing 2, an androgen target gene, promotes prostate cancer cell proliferation and migration.

PubMed

Obinata, Daisuke; Takada, Shogo; Takayama, Ken-ichi; Urano, Tomohiko; Ito, Akiko; Ashikari, Daisaku; Fujiwara, Kyoko; Yamada, Yuta; Murata, Taro; Kumagai, Jinpei; Fujimura, Tetsuya; Ikeda, Kazuhiro; Horie-Inoue, Kuniko; Homma, Yukio; Takahashi, Satoru; Inoue, Satoshi

2016-04-01

The androgen receptor (AR) plays a key role in the development of prostate cancer. AR signalling mediates the expression of androgen-responsive genes, which are involved in prostate cancer development and progression. Our previous chromatin immunoprecipitation study showed that the region of abhydrolase domain containing 2 (ABHD2) includes a functional androgen receptor binding site. In this study, we demonstrated that ABHD2 is a novel androgen-responsive gene that is overexpressed in human prostate cancer tissues. The expression levels of ABHD2 in androgen-sensitive cells were evaluated by quantitative reverse transcription polymerase chain reaction and western-blot analyses. LNCaP and VCaP cells with ABHD2 overexpression or short interfering RNA (siRNA) knockdown were used for functional analyses. ABHD2 expression was examined in clinical samples of prostate cancer by immunohistochemistry. We showed that ABHD2 expression is increased by androgen in LNCaP and VCaP cells. This androgen-induced ABHD2 expression was diminished by bicalutamide. While stable expression of ABHD2 affected the enhancement of LNCaP cell proliferation and migration, siRNA-mediated ABHD2 knockdown suppressed cell proliferation and migration. In addition, the siRNA treatment significantly repressed the tumour growth derived from LNCaP cells in athymic mice. Immunohistochemical analysis of ABHD2 expression in tumour specimens showed a positive correlation of ABHD2 immunoreactivity with high Gleason score and pathological N stage. Moreover, patients with high immunoreactivity of ABHD2 showed low cancer-specific survival rates and a resistance to docetaxel-based chemotherapy. ABHD2 is a novel androgen-regulated gene that can promote prostate cancer growth and resistance to chemotherapy, and is a novel target for diagnosis and treatment of prostate cancer. Copyright © 2016 Elsevier Ltd. All rights reserved.

ELEVATION OF C-FLIP IN CASTRATE-RESISTANT PROSTATE CANCER ANTAGONIZES THERAPEUTIC RESPONSE TO ANDROGEN-RECEPTOR TARGETED THERAPY

PubMed Central

McCourt, Clare; Maxwell, Pamela; Mazzucchelli, Roberta; Montironi, Rodolfo; Scarpelli, Marina; Salto-Tellez, Manuel; O’Sullivan, Joe M.; Longley, Daniel B.; Waugh, David J.J.

2012-01-01

Purpose To characterize the importance of cellular Fas-associated death domain (FADD)-like interleukin 1β-converting enzyme (FLICE) inhibitory protein (c-FLIP), a key regulator of caspase 8 (FLICE)-promoted apoptosis, in modulating the response of prostate cancer (CaP) cells to androgen receptor (AR)-targeted therapy. Experimental Design c-FLIP expression was characterized by immunohistochemical analysis of prostatectomy tissue. The functional importance of c-FLIP to survival and modulating response to bicalutamide was studied by molecular and pharmacological interventions. Results c-FLIP expression was increased in high-grade prostatic intra-epithelial neoplasia (HGPIN) and CaP tissue relative to normal prostate epithelium (P<0.001). Maximal c-FLIP expression was detected in castrate-resistant CaP (CRPC) (P<0.001). In vitro, silencing of c-FLIP induced spontaneous apoptosis and increased 22Rv1 and LNCaP cell sensitivity to bicalutamide, determined by flow cytometry, PARP cleavage and caspase activity assays. The histone deacetylase inhibitors (HDACi), droxinostat and SAHA, also down-regulated c-FLIP expression, induced caspase-8 and caspase-3/7 mediated apoptosis and increased apoptosis in bicalutamide-treated cells. Conversely, the elevated expression of c-FLIP detected in the CRPC cell line VCaP underpinned their insensitivity to bicalutamide and SAHA in vitro. However, knockdown of c-FLIP induced spontaneous apoptosis in VCaP cells, indicating its relevance to cell survival and therapeutic resistance. Conclusion c-FLIP reduces the efficacy of AR-targeted therapy and maintains the viability of CaP cells. A combination of HDACi with androgen-deprivation therapy (ADT) may be effective in early-stage disease, using c-FLIP expression as a predictive biomarker of sensitivity. Direct targeting of c-FLIP however may be relevant to enhance the response of existing and novel therapeutics in CRPC. PMID:22623731

Evaluation of non-viral risk factors for nasopharyngeal carcinoma in a high-risk population of Southern China

PubMed Central

Guo, Xiuchan; Johnson, Randall C.; Deng, Hong; Liao, Jian; Guan, Li; Nelson, George W.; Tang, Mingzhong; Zheng, Yuming; de The, Guy; O’Brien, Stephen J.; Winkler, Cheryl A.; Zeng, Yi

2015-01-01

To understand the role of environmental and genetic influences on nasopharyngeal carcinoma (NPC) in populations at high risk of NPC, we have performed a case-control study in Guangxi Province of Southern China in 2004-2005. NPC cases (n=1049) were compared to 785 NPC-free matched controls who were seropositive for IgA antibodies (IgA) to Epstein-Barr virus (EBV) capsid antigen (VCA)—a predictive marker for NPC in Chinese populations. A questionnaire was used to capture exposure and NPC family history data. Risk factors associated with NPC in a multivariant analysis model were the following: 1) a first, second or third degree relative with NPC [Attributable risk (AR)= 6%, Odds ratio (OR) = 3.1, 95%CI = 2.0-4.9, p < 0.001]; 2) consumption of salted fish 3 or more than 3 times per month (AR=3%, OR = 1.9, 95%CI = 1.1-3.5, p = 0.035); 3) exposure to domestic wood cooking fires for more than 10 years (AR=69%, OR = 5.8, 95%CI = 2.5-13.6, p < 0.001); and 4) exposure to occupational solvents for 10 or less years (AR=4%, OR = 2.6, 95%CI = 1.4-4.8, p = 0.002). Consumption of preserved meats or a history of tobacco smoking were not associated with NPC (P>0.05). We also assessed the contribution of EBV/IgA/VCA antibody serostatus to NPC risk—32.2% of NPC can be explained by IgA+ status. However, family history and environmental risk factors cumulatively explained only 2.7% of NPC development in NPC high risk population. These findings should have important public health implications for NPC risk reduction in endemic regions. PMID:19296536

Coping with Trial-to-Trial Variability of Event Related Signals: A Bayesian Inference Approach

NASA Technical Reports Server (NTRS)

Ding, Mingzhou; Chen, Youghong; Knuth, Kevin H.; Bressler, Steven L.; Schroeder, Charles E.

2005-01-01

In electro-neurophysiology, single-trial brain responses to a sensory stimulus or a motor act are commonly assumed to result from the linear superposition of a stereotypic event-related signal (e.g. the event-related potential or ERP) that is invariant across trials and some ongoing brain activity often referred to as noise. To extract the signal, one performs an ensemble average of the brain responses over many identical trials to attenuate the noise. To date, h s simple signal-plus-noise (SPN) model has been the dominant approach in cognitive neuroscience. Mounting empirical evidence has shown that the assumptions underlying this model may be overly simplistic. More realistic models have been proposed that account for the trial-to-trial variability of the event-related signal as well as the possibility of multiple differentially varying components within a given ERP waveform. The variable-signal-plus-noise (VSPN) model, which has been demonstrated to provide the foundation for separation and characterization of multiple differentially varying components, has the potential to provide a rich source of information for questions related to neural functions that complement the SPN model. Thus, being able to estimate the amplitude and latency of each ERP component on a trial-by-trial basis provides a critical link between the perceived benefits of the VSPN model and its many concrete applications. In this paper we describe a Bayesian approach to deal with this issue and the resulting strategy is referred to as the differentially Variable Component Analysis (dVCA). We compare the performance of dVCA on simulated data with Independent Component Analysis (ICA) and analyze neurobiological recordings from monkeys performing cognitive tasks.

The Direct Inhibitory Effect of Dutasteride or Finasteride on Androgen Receptor Activity is Cell Line Specific

PubMed Central

Chhipa, Rishi Raj; Halim, Danny; Cheng, Jinrong; Zhang, Huan Yi; Mohler, James L.; Ip, Clement; Wu, Yue

2014-01-01

BACKGROUND Finasteride and dutasteride were developed originally as 5α-reductase inhibitors to block the conversion of testosterone to dihydrotestosterone (DHT). These drugs may possess off-target effects on the androgen receptor (AR) due to their structural similarity to DHT. METHODS A total of 4 human prostate cancer cell models were examined: LNCaP (T877A mutant AR), 22Rv1 (H874Y mutant AR), LAPC4 (wild type AR) and VCaP (wild type AR). Cells were cultured in 10% charcoal-stripped fetal bovine serum, either with or without DHT added to the medium. AR activity was evaluated using the ARE-luciferase assay or the expression of AR regulated genes. RESULTS Dutasteride was more potent than finasteride in interfering with DHT-stimulated AR signaling. Disruption of AR function was accompanied by decreased cell growth. Cells that rely on DHT for protection against death were particularly vulnerable to dutasteride. Different prostate cancer cell models exhibited different sensitivities to dutasteride and finasteride. LNCaP was most sensitive, LAPC4 and VCaP were intermediate, while 22Rv1 was least sensitive. Regardless of the AR genotype, if AR was transfected into drug-sensitive cells, AR was inhibited by drug treatment; and if AR was transfected into drug-resistant cells, AR was not inhibited. CONCLUSIONS The direct inhibitory effect of dutasteride or finasteride on AR signaling is cell line specific. Mutations in the ligand binding domain of AR do not appear to play a significant role in influencing the AR antagonistic effect of these drugs. Subcellular constituent is an important factor in determining the drug effect on AR function. PMID:23813737

Combination treatment with docetaxel and histone deacetylase inhibitors downregulates androgen receptor signaling in castration-resistant prostate cancer.

PubMed

Park, Sang Eun; Kim, Ha-Gyeong; Kim, Dong Eun; Jung, Yoo Jung; Kim, Yunlim; Jeong, Seong-Yun; Choi, Eun Kyung; Hwang, Jung Jin; Kim, Choung-Soo

2018-04-01

Backgrounds Since most patients with castration-resistant prostate cancer (CRPC) develop resistance to its standard therapy docetaxel, many studies have attempted to identify novel combination treatment to meet the large clinical unmet need. In this study, we examined whether histone deacetylase inhibitors (HDACIs) enhanced the effect of docetaxel on AR signaling in CRPC cells harboring AR and its splice variants. Methods HDACIs (vorinostat and CG200745) were tested for their ability to enhance the effects of docetaxel on cell viability and inhibition of AR signaling in CRPC 22Rv1 and VCaP cells by using CellTiter-Glo™ Luminescent cell viability assay, synergy index analysis and Western blotting. The nuclear localization of AR was examined via immunocytochemical staining in 22Rv1 cells and primary tumor cells from a patient with CRPC. Results Combination treatment with HDACIs (vorinostat or CG200745) and docetaxel synergistically inhibited the growth of 22Rv1 and VCaP cells. Consistently, the combination treatment decreased the levels of full-length AR (AR-FL), AR splice variants (AR-Vs), prostate-specific antigen (PSA), and anti-apoptotic Bcl-2 proteins more efficiently compared with docetaxel or vorinostat alone. Moreover, the combination treatment accelerated the acetylation and bundling of tubulin, which significantly inhibited the nuclear accumulation of AR in 22Rv1 cells. The cytoplasmic colocalization of AR-FL and AR-V7 with microtubule bundles increased after combination treatment in primary tumor cells from a patient with CRPC. Conclusions The results suggested that docetaxel, in combination with HDACIs, suppressed the expression and nuclear translocation of AR-FL and AR-Vs and showed synergistic anti-proliferative effect in CRPC cells. This combination therapy may be useful for the treatment of patients with CRPC.

Crystallization of Chicken Egg White Lysozyme from Sulfate Salts

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth; Pusey, Marc

1998-01-01

It has been "known" that chicken egg white lysozyme does not crystallize from sulfate, particularly ammonium sulfate, salts, but instead gives amorphous precipitates. This has been the basis of several studies using lysozyme comparing macromolecule crystal nucleation and amorphous precipitation. Recently Ries-Kautt et al (Acta Cryst D50, (1994) 366) have shown that purified isoionic CEWL could be crystallized from low concentrations of sulfate at basic pH, and we subsequently showed that in fact CEWL could be purified in both the tetragonal and orthorhombic forms using ammonium sulfate over the pH range 4.0 to 7.8 (Acta Cryst D53, (1997) 795). We have now extended these observations to include a range of common sulfate salts, specifically sodium, potassium, rubidium, magnesium, and manganese sulfates. In all cases but the manganese sulfates both the familiar tetragonal and orthorhombic forms were obtained, with unit cell dimensions close to those known for the "classic" sodium chloride crystallized forms. Manganese sulfate has only yielded orthorhombic crystals to date. All crystallizations were carried out using low (typically less than or equal to 6 M) salt and high (greater than approximately 90 mg/ml) protein concentrations. As with ammonium sulfate, the tetragonal - orthorhombic phase shift appears to be a function of both the temperature and the protein concentration, with higher temperatures and concentrations favoring the orthorhombic and lower the tetragonal form. The phase change range is somewhat reduced for the sulfate salts, depending upon conditions being typically between approximately 15 - 20 C. Both the magnesium and manganese sulfates gave crystals at salt concentrations over 0.6 M as well, with magnesium sulfate giving a very slowly nucleating and growing hexagonal form. A triclinic crystal form, characterized by aggressively small crystals (typically 0.1 mm in size) has been occasionally obtained from ammonium sulfate. Finally, preliminary spot solubility determinations have suggested that in some cases the solubility increases with increasing salt concentrations.

Perovskite single crystals and thin films for optoelectronic devices (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Gang; Han, Qifeng; Yang, Yang; Bae, Sang-Hoon; Sun, Pengyu

2016-09-01

Hybrid organolead trihalide perovskite (OTP) solar cells have developed as a promising candidate in photovoltaics due to their excellent properties including a direct bandgap, strong absorption coefficient, long carrier lifetime, and high mobility. Most recently, formamidinium (NH2CH=NH2+ or FA) lead iodide (FAPbI3) has attracted significant attention due to several advantages: (1) the larger organic FA cation can replace the MA cation and form a more symmetric crystal structure, (2) the smaller bandgap of FAPbI3 allows for near infrared (NIR) absorption, and (3) FAPbI3 has an elevated decomposition temperature and thus potential to improve stability. Single crystals provide an excellent model system to study the intrinsic electrical and optical properties of these materials due to their high purity, which is particularly important to understand the limits of these materials. In this work, we report the growth of large ( 5 millimeter size) single crystal FAPbI3 using a novel liquid based crystallization method. The single crystal FAPbI3 demonstrated a δ-phase to α-phase transition with a color change from yellow to black when heated to 185°C within approximately two minutes. The crystal structures of the two phases were identified and the PL emission peak of the α-phase FAPbI3 (820 nm) shows clear red-shift compared to the FAPbI3 thin film (805 nm). The FAPbI3 single crystal shows a long carrier lifetime of 484 ns, a high carrier mobility of 4.4 cm2·V-1·s-1, and even more interestingly a conductivity of 1.1 × 10-7(ohm·cm)-1, which is approximately one order of magnitude higher than that of the MAPbI3 single crystal. Finally, high performance photoconductivity type photodetectors were successfully demonstrated using the single crystal FAPbI3.

Investigation of channeling and radiation of relativistic electrons in charged planes of the crystals with zinc blende structure

NASA Astrophysics Data System (ADS)

Maksyuta, N. V.; Vysotskii, V. I.; Efimenko, S. V.; Slinchenko, Y. A.

2018-04-01

In this paper the interaction potentials of relativistic electrons with the charged (2m+1, 2n+1, 2p+1) and (2m+1, 2n, 2p) planes (m, n, p=0,1,dot s, and Miller indices are mutually prime numbers) in the crystals with a zinc blende structure are calculated using Moliere approximation. It is shown that at the change of the type of used crystal plane (from the main (100) to the high-index charged planes), the structures of potential wells are transformed from non-unimodal to unimodal ones. In this case for the crystals constructed from ions with close nucleus charges, there arise so-called positron-like potential wells for the channeled electrons, i.e. with minima in the interplanar space. The influence of temperature factor on interaction potentials structures is also investigated. For the electrons with Lorentz-factors γ = 25, 50, 75 in the main (100) and (111) planes the transverse energy levels and corresponding wave functions in single planar approximation are found numerically. By means of these data the spectra of channeling radiation (CR) in dipole approximation are calculated for the electrons beams with a Lorentz-factor γ = 50 and an angular dispersion θ 0 ≈ 0,5 mrad, arising in the main charged (100) and (111) planes in ZnS, ZnSe and ZnTe crystals. It is shown that the CR generated at electron channeling along the (111) planes is more intense. It is shown also that spectra of CR arising in (111) planes of silicon and AlP crystals at using of channeled electron beam with γ = 25 and an angular dispersion θ 0 ≈ 0,5 mrad, due to similarity of structures of potential wells are identical. The spectra of CR at γ = 25, 50, 75 are calculated for a number of crystals with a zinc blende structure, namely AlP, AlAs, AlSb, GaP, GaAs, InP, InAs, InSb.

A view inside the nature of protein crystals

NASA Astrophysics Data System (ADS)

Oswald, R.; Pietzsch, M.; Ulrich, J.

2017-07-01

In this work a fundamental analysis of protein crystal modifications was presented to compare and confirm the components of protein crystal modifications. The result is that a protein crystal contains besides the protein, the precipitant and water. A mass spectrometer coupled to a thermogravimetry device was used to confirm the different waters (free water -the chosen buffer- and bound water) inside the crystals. Here the biggest amount of water is the free water (the buffer) with an amount of approximately 35%. The bound water (in the sense of a hydrate) has only an amount of about 1-1.5%. Furthermore, an x-ray analysis to confirm the influence range of pH value on the stability of one crystal modification for the understanding of effects on dissolution mechanism of protein crystals was investigated. The crystals of the tetragonal modification crystallized at pH 4.7, 4.85, 5.0, 5.15 and 5.3 maintain according to the x-ray measurements the same lattice parameters. The measured data are discussed.

Topographically induced homeotropic alignment of liquid crystals on self-assembled opal crystals.

PubMed

Kumar, Pankaj; Oh, Su Yeon; Baliyan, Vijay K; Kundu, Sudarshan; Lee, Seung Hee; Kang, Shin-Woong

2018-04-02

The surface of multilayered opal crystals resulted in homeotropic alignment of liquid crystal (LC), originated from the surface topography of opal crystals rather than a chemical nature of the nanoparticles. The polar anchoring energy (5.51 × 10 -5 J/m 2 ) of the crystal surface for nematic LC molecules was in a similar range to the conventional polyimide alignment layer (2.11 × 10 -5 J/m 2 ) used for commercial applications. The critical length scale for anchoring transition was approximately Lw = ~1 μm. If a diameter of particle d < 1 μm for opal crystals, LC molecules preferred to anchor vertically to the surface to minimize elastic free energy of bulk LCs. The LC favored a planar anchoring if d > 1 μm. The results provide crucial insights to understand the homeotropic alignment of LCs on solid surfaces and therefore offer opportunities to develop novel materials for a vertical alignment of LCs.

Properties of Coulomb crystals: rigorous results.

PubMed

Cioslowski, Jerzy

2008-04-28

Rigorous equalities and bounds for several properties of Coulomb crystals are presented. The energy e(N) per particle pair is shown to be a nondecreasing function of the particle number N for all clusters described by double-power-law pairwise-additive potentials epsilon(r) that are unbound at both r-->0 and r-->infinity. A lower bound for the ratio of the mean reciprocal crystal radius and e(N) is derived. The leading term in the asymptotic expression for the shell capacity that appears in the recently introduced approximate model of Coulomb crystals is obtained, providing in turn explicit large-N asymptotics for e(N) and the mean crystal radius. In addition, properties of the harmonic vibrational spectra are investigated, producing an upper bound for the zero-point energy.

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.

PubMed

Malkin, B Z; Lummen, T T A; van Loosdrecht, P H M; Dhalenne, G; Zakirov, A R

2010-07-14

The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R(2)Ti(2)O(7) (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

Synthesis, anisotropy, and superconducting properties of LiFeAs single crystal

NASA Astrophysics Data System (ADS)

Song, Yoo Jang; Ghim, Jin Soo; Min, Byeong Hun; Kwon, Yong Seung; Jung, Myung Hwa; Rhyee, Jong-Soo

2010-05-01

A LiFeAs single crystal with Tconset˜19.7 K was grown in a sealed tungsten crucible using the Bridgeman method. The electrical resistivity experiments revealed a ratio of room temperature to residual resistivity of approximately 46 and 18 for the in-plane and out-of plane directions, respectively. The estimated anisotropic resistivity, γρ=ρc/ρab, was approximately 3.3 at Tconset. The upper critical fields had large Hc2∥ab and Hc2∥c values of 83.4 T and 72.5 T, respectively, and an anisotropy ratio is γH=Hc2∥ab/Hc2∥c˜1.15. The high upper critical field value and small anisotropy highlight the potential use of LiFeAs in a variety of applications. The calculated critical current density (Jc) from the M-H loop is approximately 103 A/cm2

Optical and mechanical design of a "zipper" photonic crystal optomechanical cavity.

PubMed

Chan, Jasper; Eichenfield, Matt; Camacho, Ryan; Painter, Oskar

2009-03-02

Design of a doubly-clamped beam structure capable of localizing mechanical and optical energy at the nanoscale is presented. The optical design is based upon photonic crystal concepts in which patterning of a nanoscale-cross-section beam can result in strong optical localization to an effective optical mode volume of 0.2 cubic wavelengths ( (lambdac)(3)). By placing two identical nanobeams within the near field of each other, strong optomechanical coupling can be realized for differential motion between the beams. Current designs for thin film silicon nitride beams at a wavelength of lambda?= 1.5 microm indicate that such structures can simultaneously realize an optical Q-factor of 7x10(6), motional mass m(u) approximately 40 picograms, mechanical mode frequency Omega(M)/2pi approximately 170 MHz, and an optomechanical coupling factor (g(OM) identical with domega(c)/dx = omega(c)/L(OM)) with effective length L(OM) approximately lambda= 1.5 microm.

A novel polyamine allosteric site of SpeG from Vibrio cholerae is revealed by Its dodecameric structure

DOE PAGES

Filippova, Ekaterina V.; Kuhn, Misty L.; Osipiuk, Jerzy; ...

2015-01-23

Spermidine N-acetyltransferase, encoded by the gene speG, catalyzes the initial step in the degradation of polyamines and is a critical enzyme for determining the polyamine concentrations in bacteria. In Escherichia coli, studies have shown that SpeG is the enzyme responsible for acetylating spermidine under stress conditions and for preventing spermidine toxicity. Not all bacteria contain speG, and many bacterial pathogens have developed strategies to either acquire or silence it for pathogenesis. Here, we present thorough kinetic analyses combined with structural characterization of the VCA0947 SpeG enzyme from the important human pathogen Vibrio cholerae. Our studies revealed the unexpected presence ofmore » a previously unknown allosteric site and an unusual dodecameric structure for a member of the Gcn5-related N-acetyltransferase superfamily. We show that SpeG forms dodecamers in solution and in crystals and describe its three-dimensional structure in several ligand-free and liganded structures. Importantly, these structural data define the first view of a polyamine bound in an allosteric site of an N-acetyltransferase. Kinetic characterization of SpeG from V. cholerae showed that it acetylates spermidine and spermine. The behavior of this enzyme is complex and exhibits sigmoidal curves and substrate inhibition. We performed a detailed non-linear regression kinetic analysis to simultaneously fit families of substrate saturation curves to uncover a simple kinetic mechanism that explains the apparent complexity of this enzyme. Our results provide a fundamental understanding of the bacterial SpeG enzyme, which will be key toward understanding the regulation of polyamine levels in bacteria during pathogenesis.« less

A novel polyamine allosteric site of SpeG from Vibrio cholerae is revealed by its dodecameric structure.

PubMed

Filippova, Ekaterina V; Kuhn, Misty L; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Ballicora, Miguel A; Anderson, Wayne F

2015-03-27

Spermidine N-acetyltransferase, encoded by the gene speG, catalyzes the initial step in the degradation of polyamines and is a critical enzyme for determining the polyamine concentrations in bacteria. In Escherichia coli, studies have shown that SpeG is the enzyme responsible for acetylating spermidine under stress conditions and for preventing spermidine toxicity. Not all bacteria contain speG, and many bacterial pathogens have developed strategies to either acquire or silence it for pathogenesis. Here, we present thorough kinetic analyses combined with structural characterization of the VCA0947 SpeG enzyme from the important human pathogen Vibrio cholerae. Our studies revealed the unexpected presence of a previously unknown allosteric site and an unusual dodecameric structure for a member of the Gcn5-related N-acetyltransferase superfamily. We show that SpeG forms dodecamers in solution and in crystals and describe its three-dimensional structure in several ligand-free and liganded structures. Importantly, these structural data define the first view of a polyamine bound in an allosteric site of an N-acetyltransferase. Kinetic characterization of SpeG from V. cholerae showed that it acetylates spermidine and spermine. The behavior of this enzyme is complex and exhibits sigmoidal curves and substrate inhibition. We performed a detailed non-linear regression kinetic analysis to simultaneously fit families of substrate saturation curves to uncover a simple kinetic mechanism that explains the apparent complexity of this enzyme. Our results provide a fundamental understanding of the bacterial SpeG enzyme, which will be key toward understanding the regulation of polyamine levels in bacteria during pathogenesis. Copyright © 2015. Published by Elsevier Ltd.

A novel polyamine allosteric site of SpeG from Vibrio cholerae is revealed by Its dodecameric structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filippova, Ekaterina V.; Kuhn, Misty L.; Osipiuk, Jerzy

Spermidine N-acetyltransferase, encoded by the gene speG, catalyzes the initial step in the degradation of polyamines and is a critical enzyme for determining the polyamine concentrations in bacteria. In Escherichia coli, studies have shown that SpeG is the enzyme responsible for acetylating spermidine under stress conditions and for preventing spermidine toxicity. Not all bacteria contain speG, and many bacterial pathogens have developed strategies to either acquire or silence it for pathogenesis. Here, we present thorough kinetic analyses combined with structural characterization of the VCA0947 SpeG enzyme from the important human pathogen Vibrio cholerae. Our studies revealed the unexpected presence ofmore » a previously unknown allosteric site and an unusual dodecameric structure for a member of the Gcn5-related N-acetyltransferase superfamily. We show that SpeG forms dodecamers in solution and in crystals and describe its three-dimensional structure in several ligand-free and liganded structures. Importantly, these structural data define the first view of a polyamine bound in an allosteric site of an N-acetyltransferase. Kinetic characterization of SpeG from V. cholerae showed that it acetylates spermidine and spermine. The behavior of this enzyme is complex and exhibits sigmoidal curves and substrate inhibition. We performed a detailed non-linear regression kinetic analysis to simultaneously fit families of substrate saturation curves to uncover a simple kinetic mechanism that explains the apparent complexity of this enzyme. Our results provide a fundamental understanding of the bacterial SpeG enzyme, which will be key toward understanding the regulation of polyamine levels in bacteria during pathogenesis.« less

Fluctuation conductivity of oxygen underdoped YBa2Cu3O7-δ single crystals

NASA Astrophysics Data System (ADS)

Vovk, R. V.; Khadzhai, G. Ya.; Goulatis, I. L.; Chroneos, A.

2014-03-01

The electrical resistance in the range of ТC-300 K in the layer planes of YВа2Сu3О7-δ single crystals with a range of oxygen deficiency (providing a range of TC from 78 to 92 K) was investigated. The experimental data is approximated by an expression that accounts for the scattering of electrons on phonons, as well as on defects and the fluctuation conductivity in a 3-D model of the Aslamazov-Larkin theory. According to this approximation, depending upon the oxygen deficiency, the Debye temperature varies from 245 to 400 K, coherence length ξС(0)≈0.5 Å.

Crystal Structure, Conformational Analysis, and Charge Density Distribution for Eng-Epifisetinidol: An Explanation for Regiospecific Aromatic Substitution of 5-Deoxyflavan

Treesearch

Fred L. Tobiason; Frank R. Fronczek; Jan P. Steynberg; Elizabeth C. Steynberg; Richard W. Hemingway; Wayne L. Mattice

1993-01-01

Molecular modeling and molecular orbital analyses of ent-epifisetinidol gave &ood predictions of the approximate "reverse half-chair" conformation found for the crystal structure. MNDO and AM1 analyses of HOMO electron densities provided an explanation for the stereospecific electrophilic aromatic substitution at C(6) in 5-deoxy-flavans...

Common Misconceptions about the Dynamical Theory of Crystal Lattices: Cauchy Relations, Lattice Potentials and Infinite Crystals

ERIC Educational Resources Information Center

Elcoro, Luis; Etxebarria, Jesus

2011-01-01

The requirement of rotational invariance for lattice potential energies is investigated. Starting from this condition, it is shown that the Cauchy relations for the elastic constants are fulfilled if the lattice potential is built from pair interactions or when the first-neighbour approximation is adopted. This is seldom recognized in widely used…

Forces Generated by High Velocity Impact of Ice on a Rigid Structure

NASA Technical Reports Server (NTRS)

Pereira, J. Michael; Padula, Santo A., II; Revilock, Duane M.; Melis, Matthew E.

2006-01-01

Tests were conducted to measure the impact forces generated by cylindrical ice projectiles striking a relatively rigid target. Two types of ice projectiles were used, solid clear ice and lower density fabricated ice. Three forms of solid clear ice were tested: single crystal, poly-crystal, and "rejected" poly-crystal (poly-crystal ice in which defects were detected during inspection.) The solid ice had a density of approximately 56 lb/cu ft (0.9 gm/cu cm). A second set of test specimens, termed "low density ice" was manufactured by molding shaved ice into a cylindrical die to produce ice with a density of approximately 40 lb/cu ft (0.65 gm/cu cm). Both the static mechanical characteristics and the crystalline structure of the ice were found to have little effect on the observed transient response. The impact forces generated by low density ice projectiles, which had very low mechanical strength, were comparable to those of full density solid ice. This supports the hypothesis that at a velocity significantly greater than that required to produce fracture in the ice, the mechanical properties become relatively insignificant, and the impact forces are governed by the shape and mass of the projectile.

A dislocation-based crystal plasticity framework for dynamic ductile failure of single crystals

NASA Astrophysics Data System (ADS)

Nguyen, Thao; Luscher, D. J.; Wilkerson, J. W.

2017-11-01

A framework for dislocation-based viscoplasticity and dynamic ductile failure has been developed to model high strain rate deformation and damage in single crystals. The rate-dependence of the crystal plasticity formulation is based on the physics of relativistic dislocation kinetics suited for extremely high strain rates. The damage evolution is based on the dynamics of void growth, which are governed by both micro-inertia as well as dislocation kinetics and dislocation substructure evolution. An averaging scheme is proposed in order to approximate the evolution of the dislocation substructure in both the macroscale as well as its spatial distribution at the microscale. Additionally, a concept of a single equivalent dislocation density that effectively captures the collective influence of dislocation density on all active slip systems is proposed here. Together, these concepts and approximations enable the use of semi-analytic solutions for void growth dynamics developed in (Wilkerson and Ramesh, 2014), which greatly reduce the computational overhead that would otherwise be required. The resulting homogenized framework has been implemented into a commercially available finite element package, and a validation study against a suite of direct numerical simulations was carried out.

Hypernetted-chain-like closure of Ornstein-Zernike equation in multibody dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Mo, Chao-jie; Qin, Li-zi; Yang, Li-jun

2017-10-01

We have derived a hypernetted-chain-like (HNC-like) approximate closure of the Ornstein-Zernike equation for multibody dissipative particle dynamics (MDPD) system in which the classic closures are not directly practicable. We first point out that the Percus's method is applicable to MDPD system in which particles interact with a density-dependent potential. And then an HNC-like closure is derived using Percus's idea and the saddle-point approximation of particle free energy. This HNC-like closure is compared with results of previous researchers, and in many cases, it demonstrates better agreement with computer simulation results. The HNC-like closure is used to predict the cluster crystallization in MDPD. We determine whether the cluster crystallization will happen in a system utilizing the widely applicable Hansen-Verlet freezing criterion and by observing the radial distribution function. The conclusions drawn from the results of the HNC-like closure are in agreement with computer simulation results. We evaluate different weight functions to determine whether they are prone to cluster crystallization. A new effective density-dependent pairwise potential is also proposed to help to explain the tendency to cluster crystallization of MDPD systems.

Investigation of Methods to Eliminate Voltage Delay in Li/SOCl2 Cells.

DTIC Science & Technology

1980-05-01

of storage at 550C the surface was completely covered with cubic crystals averaging about 8 pim on an edge (Figure 24). The lithium surface stored at...completely covered with cubic crystals, showing no smooth undercoating at all (Figure 25). The average crystal diameter was approximately 3.3 pim , with a...used. ithi timl acgu ire0d A Ci yst al I me surt ace, oil dr n torage at elevated temlper aI Ite t. T[he out lace, showed ch[ ott ine by EPAC except

Crystal growth of incommensurate members of 2H-hexagonal perovskite related oxides: Ba{sub 4}M{sub z}Pt{sub 3−z}O{sub 9} (M=Co, Ni, Cu, Zn, Mg, Pt)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, Timothy; Morrison, Gregory; Yeon, Jeongho

2016-04-15

Millimeter sized crystals of six oxides of approximate composition Ba{sub 4}M{sub z}Pt{sub 3-z}O{sub 9} (M=Co, Ni, Cu, Zn, Mg, Pt) were grown from molten K{sub 2}CO{sub 3} fluxes and found to crystallize in a 2H hexagonal perovskite-related structure type. The compositions of these incommensurate structures, which belong to the A{sub 3n+3m}A′{sub n}B{sub 3m+n}O{sub 9m+6n} family of 2H hexagonal perovskite related oxides, were characterized by X-ray diffraction, energy dispersive spectroscopy, and magnetic susceptibility measurements. The specific synthetic considerations, crystal growth conditions, and magnetic susceptibility measurements are discussed. - Graphical abstract: SEM image and average commensurate unit cell of Ba{sub 4}Pt{sub 3}O{submore » 9.} - Highlights: • Single crystals of the series Ba{sub 4}A′{sub z}Pt{sub 3-z}O{sub 9} were grown via a molten carbonate flux. • Ba{sub 4}Pt{sub 3}O{sub 9} and all substitutional variants are incommensurate, composite structures. • All compounds have an approximate stoichiometry of Ba{sub 4}A′Pt{sub 2}O{sub 9.}.« less

A Flexible Parameterization for Shortwave Optical Properties of Ice Crystals

NASA Technical Reports Server (NTRS)

VanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Cairns, Brian; Fridlind, Ann M.

2014-01-01

A parameterization is presented that provides extinction cross section sigma (sub e), single-scattering albedo omega, and asymmetry parameter (g) of ice crystals for any combination of volume, projected area, aspect ratio, and crystal distortion at any wavelength in the shortwave. Similar to previous parameterizations, the scheme makes use of geometric optics approximations and the observation that optical properties of complex, aggregated ice crystals can be well approximated by those of single hexagonal crystals with varying size, aspect ratio, and distortion levels. In the standard geometric optics implementation used here, sigma (sub e) is always twice the particle projected area. It is shown that omega is largely determined by the newly defined absorption size parameter and the particle aspect ratio. These dependences are parameterized using a combination of exponential, lognormal, and polynomial functions. The variation of (g) with aspect ratio and crystal distortion is parameterized for one reference wavelength using a combination of several polynomials. The dependences of g on refractive index and omega are investigated and factors are determined to scale the parameterized (g) to provide values appropriate for other wavelengths. The parameterization scheme consists of only 88 coefficients. The scheme is tested for a large variety of hexagonal crystals in several wavelength bands from 0.2 to 4 micron, revealing absolute differences with reference calculations of omega and (g) that are both generally below 0.015. Over a large variety of cloud conditions, the resulting root-mean-squared differences with reference calculations of cloud reflectance, transmittance, and absorptance are 1.4%, 1.1%, and 3.4%, respectively. Some practical applications of the parameterization in atmospheric models are highlighted.

Peculiarities of Crystallization of the Restriction Endonuclease EcoRII

NASA Technical Reports Server (NTRS)

Karpove, Elizaveta; Pusey, M.arc L.

1998-01-01

Nucleases interfere with most standard molecular biology procedures. We have purified and crystallized the restriction endonuclease EcoRII, which belongs to the type II of restriction- modification enzyme, to study the protein crystallization process using a "non standard" macromolecule. A procedure for the purification of EcoRII was developed and 99% pure protein as determined by SDS PAGE electrophoresis obtained. Light scattering experiments were performed to assist in screening protein suitable crystallization conditions. The second virial coefficient was determined as a function of precipitating salt concentration, using sodium chloride, ammonium sulfate, and sodium sulfate. Small (maximum size approximately 0.2 mm) well shaped crystals have been obtained. Larger poorly formed crystals (ca 0.5 mm) have also been obtained, but we have been unable to mount them for diff-raction analysis due to their extreme fragility. Crystallization experiments with PEG have shown that using this precipitant, the best crystals are obtained from slightly over-saturated solutions. Use of higher precipitant concentration leads to dendritic crystal formation. EcoRII is difficult to solubilize and meticulous attention must be paid to the presence of reducing agents.

Characterization of the electro-optic effect in styrylpyridinium cyanine dye thin-film crystals by an ac modulation method

NASA Astrophysics Data System (ADS)

Yoshimura, Tetsuzo

1987-09-01

The electro-optic effect in styrylpyridinium cyanine dye (SPCD) thin-film crystals is characterized by a newly developed ac modulation method that is effective in characterizing thin-film materials of small area. SPCD thin-film crystals 3-10 μm thick were grown from a methanol solution of SPCD. The crystal shows strong dichroism and anisotropy of refractive index, indicating that molecular dipole moments align along a definite direction (z axis). When an electric field is applied along the z axis, SPCD thin-film crystals show a large figure of merit of electro-optic phase retardation of 6.5×10-10 m/V, which is 5 times as large as in LiNbO3 crystal, 2 times that in 2-methyl-4-nitroaniline (MNA) crystal, and is the largest ever reported in organic solids. The electro-optic coefficient r33 of SPCD crystals is estimated to be approximately 4.3×10-10 m/V, which is 6 times larger than that of an MNA crystal. This value is consistent with that expected from second-harmonic generation measurements.

Structural analysis of as-deposited and annealed low-temperature gallium arsenide

NASA Astrophysics Data System (ADS)

Matyi, R. J.; Melloch, M. R.; Woodall, J. M.

1993-04-01

The structure of GaAs grown at low substrate temperatures (LT-GaAs) by molecular beam epitaxy has been studied using high resolution X-ray diffraction methods. Double crystal rocking curves from the as-deposited LT-GaAs show well defined interference fringes, indicating a high level of structural perfection. Triple crystal diffraction analysis of the as-deposited sample showed significantly less diffuse scattering near the LT-GaAs 004 reciprocal lattice point compared with the substrate 004 reciprocal lattice point, suggesting that despite the incorporation of approximately 1% excess arsenic, the epitaxial layer had superior crystalline perfection than did the GaAs substrate. Triple crystal scans of annealed LT-GaAs showed an increase in the integrated diffuse intensity by approximately a factor of three as the anneal temperature was increased from 700 to 900°C. Analogous to the effects of SiO2 precipitates in annealed Czochralski silicon, the diffuse intensity is attributed to distortions in the epitaxial LT-GaAs lattice by arsenic precipitates.

Spectroscopic studies and crystal-field analyses of Am{sup 3+}: LiYF{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavellec, R.; Hubert, S.; Simoni, E.

1997-03-01

Fluorescence and laser selective excitation spectroscopy have been used to investigate the electronic energy level structure of the actinide Am{sup 3+} (5{line_integral}{sup 6}) in LiYF{sub 4}. From the analysis of the fluorescence in the visible and infrared spectra obtained at 10K, 29 crystal-field levels have been assigned in the D{sub 2d} approximation. Zeeman splitting observation permits one to index some doubly degenerated {Gamma}{sub 5} levels. The phenomenological crystal-field parameters have been calculated in the D{sub 2d} approximation. A least-square adjustment yields a mean error of 38 cm{sup {minus}1} with the following values (in cm{sup {minus}1}) of the B{sub q}{sup k}more » parameters: B{sub O}{sup 2} = 473, B{sub 0}{sup 4} = -1776, B{sub 4}{sup 4}=2253, B{sub 0}{sup 6} = 80, and B{sub 4}{sup 6} = -2222.« less

Grazing-incidence X-ray diffraction from a crystal with subsurface defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaevskii, A. Yu., E-mail: transilv@mail.ru; Golentus, I. E.

2015-03-15

The diffraction of X rays incident on a crystal surface under grazing angles under conditions of total external reflection has been investigated. An approach is proposed in which exact solutions to the dynamic problem of grazing-incidence diffraction in an ideal crystal are used as initial functions to calculate the diffuse component of diffraction in a crystal with defects. The diffuse component of diffraction is calculated for a crystal with surface defects of a dilatation-center type. Exact formulas of the continuum theory which take into account the mirror-image forces are used for defect-induced atomic displacements. Scattering intensity maps near Bragg peaksmore » are constructed for different scan modes, and the conditions for detecting primarily the diffuse component are determined. The results of dynamic calculations of grazing-incidence diffraction in defect-containing crystals are compared with calculations in the kinematic approximation.« less

Solid-state properties and crystallization behavior of PHA-739521 polymorphs.

PubMed

Sun, Changquan Calvin

2006-08-17

PHA-739521 is an experimental compound that exhibits polymorphism. The two anhydrous crystal forms, I and II, are characterized using powder X-ray diffractometry, thermal analyses, moisture sorption gravimetry. Both Forms I and II are non-hygroscopic and are stable to compaction pressure. The melting temperature is about 152 degrees C for Form I and 168 degrees C for Form II. Forms I and II are enantiotropically related where Form I is more stable below a transition temperature of approximately 70 degrees C. Crystallization behavior of this compound from solutions and during heating is also studied. Information obtained is used to design an appropriate crystallization process to successfully manufacture desired polymorph at large scale.

Fluorescence Studies of Protein Crystallization Interactions

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Smith, Lori; Forsythe, Elizabeth

1999-01-01

We are investigating protein-protein interactions in under- and over-saturated crystallization solution conditions using fluorescence methods. The use of fluorescence requires fluorescent derivatives where the probe does not markedly affect the crystal packing. A number of chicken egg white lysozyme (CEWL) derivatives have been prepared, with the probes covalently attached to one of two different sites on the protein molecule; the side chain carboxyl of ASP 101, within the active site cleft, and the N-terminal amine. The ASP 101 derivatives crystallize while the N-terminal amine derivatives do not. However, the N-terminal amine is part of the contact region between adjacent 43 helix chains, and blocking this site does would not interfere with formation of these structures in solution. Preliminary FRET data have been obtained at pH 4.6, 0.1M NaAc buffer, at 5 and 7% NaCl, 4 C, using the N-terminal bound pyrene acetic acid (PAA, Ex 340 nm, Em 376 nm) and ASP 101 bound Lucifer Yellow (LY, Ex 425 nm, Em 525 nm) probe combination. The corresponding Csat values are 0.471 and 0.362 mg/ml (approximately 3.3 and approximately 2.5 x 10 (exp 5) M respectively), and all experiments were carried out at approximately Csat or lower total protein concentration. The data at both salt concentrations show a consistent trend of decreasing fluorescence yield of the donor species (PAA) with increasing total protein concentration. This decrease is apparently more pronounced at 7% NaCl, consistent with the expected increased intermolecular interactions at higher salt concentrations (reflected in the lower solubility). The estimated average distance between protein molecules at 5 x 10 (exp 6) M is approximately 70 nm, well beyond the range where any FRET can be expected. The calculated RO, where 50% of the donor energy is transferred to the acceptor, for the PAA-CEWL * LY-CEWL system is 3.28 nm, based upon a PAA-CEWL quantum efficiency of 0.41.

Low-molecular-weight poly(alpha-methyl beta,L-malate) of microbial origin: synthesis and crystallization.

PubMed

Fernández, Carlos E; Mancera, Manuel; Holler, Eggehard; Bou, Jordi J; Galbis, Juan A; Muñoz-Guerra, Sebastián

2005-02-23

Low-molecular-weight poly(alpha-methyl beta,L-malate) made of approximately 25-30 units was prepared from microbial poly(beta,L-malic acid) by treatment with diazomethane. The thermal characterization of the polymalate methyl ester was carried out and its crystalline structure was preliminary examined. Its ability to crystallize both from solution and from the melt was comparatively evaluated.

Cyclic growth and dissolution of camphor crystals in quinary, ternary, and binary solutions: A study on crystal behavior in storm glass

NASA Astrophysics Data System (ADS)

Mitsuya, Takuro; Takahashi, Kyohei; Nagashima, Kazushige

2014-09-01

"Storm glass" is a hermetically sealed glass tube containing a solution of camphor. In 19th-century England, the pattern and quantity of the crystals were observed and interpreted as a weather forecasting tool. In the present study, the appearance of camphor crystals under cyclic temperature change was studied in three sample solutions, the storm glass solution (quinary system), camphor-ethanol-water (ternary system), and camphor-ethanol (binary system), to elucidate the effect of components in the storm glass on the appearance of camphor crystals. Equilibrium temperatures of camphor crystals as a function of the camphor concentration were also obtained to estimate the quantity of camphor crystals precipitated in the solutions. During the temperature cycles, the crystal height increased and decreased. The ranges (local maxima and minima) of crystal heights gradually decreased to approximately a constant range. Not only the crystal height but also the amplitude of the height variation in the quinary and ternary systems were much larger than those in the binary system, although the estimated weights of crystals precipitated in the quinary and ternary systems were smaller than that in the binary system. This fact resulted from the formation of dendrites in the quinary and ternary systems, which caused high porosity of sedimented crystals.

Preparative crystallization of a single chain antibody using an aqueous two-phase system.

PubMed

Huettmann, Hauke; Berkemeyer, Matthias; Buchinger, Wolfgang; Jungbauer, Alois

2014-11-01

A simultaneous crystallization and aqueous two-phase extraction of a single chain antibody was developed, demonstrating process integration. The process conditions were designed to form an aqueous two-phase system, and to favor crystallization, using sodium sulfate and PEG-2000. At sufficiently high concentrations of PEG, a second phase was generated in which the protein crystallization occurred simultaneously. The single chain antibody crystals were partitioned to the top, polyethylene glycol-rich phase. The crystal nucleation took place in the sodium sulfate-rich phase and at the phase boundary, whereas crystal growth was progressing mainly in the polyethylene glycol-rich phase. The crystals in the polyethylene glycol-rich phase grew to a size of >50 µm. Additionally, polyethylene glycol acted as an anti-solvent, thus, it influenced the crystallization yield. A phase diagram with an undersaturation zone, crystallization area, and amorphous precipitation zone was established. Only small differences in polyethylene glycol concentration caused significant shifts of the crystallization yield. An increase of the polyethylene glycol content from 2% (w/v) to 4% (w/v) increased the yield from approximately 63-87%, respectively. Our results show that crystallization in aqueous two-phase systems is an opportunity to foster process integration. © 2014 Wiley Periodicals, Inc.

Approximate analytic expression for the Skyrmions crystal

NASA Astrophysics Data System (ADS)

Grandi, Nicolás; Sturla, Mauricio

2018-01-01

We find approximate solutions for the two-dimensional nonlinear Σ-model with Dzyalioshinkii-Moriya term, representing magnetic Skyrmions. They are built in an analytic form, by pasting different approximate solutions found in different regions of space. We verify that our construction reproduces the phenomenology known from numerical solutions and Monte Carlo simulations, giving rise to a Skyrmion lattice at an intermediate range of magnetic field, flanked by spiral and spin-polarized phases for low and high magnetic fields, respectively.

Superconducting Bi1.5Pb0.5Sr2Ca2Cu3O(x) ceramics by rapid melt quenching and glass crystallization

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1989-01-01

A glass of nominal Bi(1.5)Pb(0.5)Sr2Ca2Cu3O(x) composition, prepared by rapid quenching of the melt, showed a glass transition temperature of 383 C, crystallization temperature of 446 C, melting temperature of 855 C, and bulk density of 5.69 g/cu cm in air. The activation energy for crystallization of the glass was estimated to be 292kJ/mol from non-isothermal DSC. On heating in oxygen, the glass showed a slow and continuous weight gain starting at approximately 530 C which reached a plateau at approximately 820 C. The weight gained during heating was retained on cooling to ambient conditions indicating an irreversible oxidation step. The influence of annealing conditions on the formation of various phases in the glass has been investigated. The Bi(2)Sr(2)Ca(0)Cu(1)O(6) phase crystallized out first followed by formation of other phases at higher temperatures. The high-T(sub c) phase, isostructural with Bi(2)Sr(2)Ca(2)Cu(3)O(10) was not detected below 840 C, but its fraction increased with the annealing time at 840 C. A sample annealed at 840 C for 243h in air and furnace cooled showed the highest T(sub c)(R=0) of 107.2K and a narrow transition width, delta T(sub c)(10 to 90 percent), of approximately 2 K. The high T(sub c) phase does not seem to crystallize out directly from the glass but is rather produced at high temperature by reaction between the phases formed at lower temperatures. The kinetics of 110K phase formation was sluggish. It appears that the presence of lead helps in the formation and/or stabilization of the 110 K phase.

A series approximation model for optical light transport and output intensity field distribution in large aspect ratio cylindrical scintillation crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tobias, Benjamin John

A series approximation has been derived for the transport of optical photons within a cylindrically symmetric light pipe and applied to the task of evaluating both the origin and angular distribution of light reaching the output plane. This analytic expression finds particular utility in first-pass photonic design applications since it may be evaluated at a very modest computational cost and is readily parameterized for relevant design constraints. It has been applied toward quantitative exploration of various scintillation crystal preparations and their impact on both quantum efficiency and noise, reproducing sensible dependencies and providing physical justification for certain gamma ray cameramore » design choices.« less

Crystallization of the Pulsating White Dwarf Star, BPM 37093

NASA Astrophysics Data System (ADS)

Salois, Amee; Winget, D.

2010-01-01

BPM 37093 is unique among pulsating white dwarf stars because it is expected to have a highly crystallized interior. By understanding how this star is crystallizing, we gain a better understanding of extreme physics. Theoretical models of the evolution of white dwarf stars suggest that they crystallize from the inside out. The pulsations of the star, which we see as intensity variations, cannot penetrate this crystallized interior. Therefore, as the star crystallizes there is a smaller volume for the propagation of the pulsations and the pulsation periods are changed accordingly. We studied these changes in the periods of the pulsations of the star over ten weeks during the McDonald Observatory Research Experience for Undergraduates Program. By studying the changes in the pulsations periods of the star we can determine the mass fraction of the star that is crystallized. Comparing Fourier transforms of our observed light curves taken in 2004 and 2005 at CTIO with data taken in 1998 and 1999 by Kanaan et al. we hope to see the changes that have occurred in the star as well as determining a better approximation of the star's crystallized mass fraction.

Locomotion in a liquid crystal near a wall

NASA Astrophysics Data System (ADS)

Powers, Thomas; Krieger, Madison; Spagnolie, Saverio

2015-11-01

Recent observations of bacteria swimming in nematic liquid crystal solution motivate the theoretical study of how swimming speed depends on liquid crystal properties. We consider the Taylor sheet near a wall, in which propulsion is achieved by the propagation of traveling waves along the length of the swimmer. Using the lubrication approximation, we determine how swimming speed depends on the Ericksen number, which is the ratio of elastic to viscous stresses. We also study the effect of anchoring strength, at the surface of the swimmer and the surface of the wall. Supported by NSF-CBET 1437195.

Analytical studies on the crystal melt interface shape in the Czochralski process for oxide single crystals

NASA Astrophysics Data System (ADS)

Jeong, Ja Hoon; Kang, In Seok

2000-09-01

Effects of the operating conditions on the crystal-melt interface shape are analytically investigated for the Czochralski process of the oxide single crystals. The ideas, which were used for the silicon single-crystal growth by Jeong et al. (J. Crystal Growth 177 (1997) 157), are extended to the oxide single-crystal growth problem by considering the internal radiation in the crystal phase and the melt phase heat transfer with the high Prandtl number. The interface shape is approximated in the simplest form as a quadratic function of radial position and an expression for the deviation from the flat interface shape is derived as a function of operating conditions. The radiative heat transfer rate between the interface and the ambient is computed by calculating the view factors for the curved interface shape with the assumption that the crystal phase is completely transparent. For the melt phase, the well-known results from the thermal boundary layer analysis are applied for the asymptotic case of high Prandtl number based on the idea that the flow field near the crystal-melt interface can be modeled as either a uniaxial or a biaxial flow. Through this work, essential information on the interface shape deformation and the effects of operating conditions are brought out for the oxide single-crystal growth.

Dynamic global model of oxide Czochralski process with weighing control

NASA Astrophysics Data System (ADS)

Mamedov, V. M.; Vasiliev, M. G.; Yuferev, V. S.

2011-03-01

A dynamic model of oxide Czochralski growth with weighing control has been developed for the first time. A time-dependent approach is used for the calculation of temperature fields in different parts of a crystallization set-up and convection patterns in a melt, while internal radiation in crystal is considered in a quasi-steady approximation. A special algorithm is developed for the calculation of displacement of a triple point and simulation of a crystal surface formation. To calculate variations in the heat generation, a model of weighing control with a commonly used PID regulator is applied. As an example, simulation of the growth process of gallium-gadolinium garnet (GGG) crystals starting from the stage of seeding is performed.

Wavelength-scale photonic-crystal laser formed by electron-beam-induced nano-block deposition.

PubMed

Seo, Min-Kyo; Kang, Ju-Hyung; Kim, Myung-Ki; Ahn, Byeong-Hyeon; Kim, Ju-Young; Jeong, Kwang-Yong; Park, Hong-Gyu; Lee, Yong-Hee

2009-04-13

A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.

Method for estimating the morphological significance of simple forms of crystals from X-ray data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Treivus, E. B., E-mail: sbobr1@bk.ru

2010-09-15

When developing V.I. Mikheev and I.I. Shafranovskii's method for estimating the morphological significance of faces of different simple forms from X-ray reflection intensities, a way to approximately evaluate the morphological significance of simple forms on crystals from the structure amplitudes of the corresponding atomic planes is proposed. The potential for this approach is demonstrated by the examples of marcasite and zircon.

A dislocation-based crystal plasticity framework for dynamic ductile failure of single crystals

DOE PAGES

Nguyen, Thao; Luscher, D. J.; Wilkerson, J. W.

2017-08-02

We developed a framework for dislocation-based viscoplasticity and dynamic ductile failure to model high strain rate deformation and damage in single crystals. The rate-dependence of the crystal plasticity formulation is based on the physics of relativistic dislocation kinetics suited for extremely high strain rates. The damage evolution is based on the dynamics of void growth, which are governed by both micro-inertia as well as dislocation kinetics and dislocation substructure evolution. Furthermore, an averaging scheme is proposed in order to approximate the evolution of the dislocation substructure in both the macroscale as well as its spatial distribution at the microscale. Inmore » addition, a concept of a single equivalent dislocation density that effectively captures the collective influence of dislocation density on all active slip systems is proposed here. Together, these concepts and approximations enable the use of semi-analytic solutions for void growth dynamics developed in [J. Wilkerson and K. Ramesh. A dynamic void growth model governed by dislocation kinetics. J. Mech. Phys. Solids, 70:262–280, 2014.], which greatly reduce the computational overhead that would otherwise be required. The resulting homogenized framework has been implemented into a commercially available finite element package, and a validation study against a suite of direct numerical simulations was carried out.« less

Mechanics of biomimetic systems propelled by actin comet tails

NASA Astrophysics Data System (ADS)

Kang, Hyeran; Tambe, Dhananjay; Shenoy, Vivek; Tang, Jay

2009-03-01

The motility of intracellular bacterial pathogens such as Listeria monocytogenes is driven by filamentous actin comet tails in a variety of trajectories. Here, we present the in vitro study on the actin-based movements using spherical beads of different sizes coated with VCA protein, a partial domain of N-Wasp, in platelet extracts. Long term two-dimensional trajectories of the spherical beads motility show characteristic difference than those observed for bacteria, which have both elongated shape and asymmetric expression of the polymerization inducing enzyme. The trajectories also vary sensitively with the bead size and shape. These results provide a useful test to our new analytical model including the rotation of the bead relative to the tail.

Classification of the crystallization behavior of amorphous active pharmaceutical ingredients in aqueous environments.

PubMed

Van Eerdenbrugh, Bernard; Raina, Shweta; Hsieh, Yi-Ling; Augustijns, Patrick; Taylor, Lynne S

2014-04-01

To classify the crystallization behavior of amorphous active pharmaceutical ingredients (API) exposed to aqueous environments. A set of approximately 50 chemically and physically diverse active pharmaceutical ingredients (APIs) was selected for this study. Two experimental setups were employed to characterize the crystallization behavior of the amorphous API in an aqueous environment. For the first approach, precipitation, as evidenced by the development of turbidity, was induced using the solvent shift method, by mixing concentrated API solutions in DMSO with an aqueous buffer in a capillary. Subsequently, crystallization was monitored in situ over time using synchrotron radiation (simultaneous SAXS/WAXS beamline 12-ID-B at the Advanced Photon Source, Argonne National Laboratories, Argonne, IL). In the second approach, amorphous films were prepared by melt quenching; after adding buffer, crystallization was monitored with time using polarized light microscopy. In general, the crystallization behavior of a given compound was similar irrespective of the experimental method employed. However, the crystallization behavior among different compounds varied significantly, ranging from immediate and complete crystallization to no observable crystallization over biorelevant time scales. Comparison of the observed behavior with previous studies of crystallization tendency in non-aqueous environments revealed that the crystallization tendency of individual APIs was somewhat similar regardless of the crystallization environment. API properties, rather than the method by which amorphous materials are generated, tend to dictate crystallization behavior in aqueous media.

Cotectic proportions of olivine and spinel in olivine-tholeiitic basalt and evaluation of pre-eruptive processes

USGS Publications Warehouse

Roeder, Peter; Gofton, Emma; Thornber, Carl

2006-01-01

The volume %, distribution, texture and composition of coexisting olivine, Cr-spinel and glass has been determined in quenched lava samples from Hawaii, Iceland and mid-oceanic ridges. The volume ratio of olivine to spinel varies from 60 to 2800 and samples with >0·02% spinel have a volume ratio of olivine to spinel of approximately 100. A plot of wt % MgO vs ppm Cr for natural and experimental basaltic glasses suggests that the general trend of the glasses can be explained by the crystallization of a cotectic ratio of olivine to spinel of about 100. One group of samples has an olivine to spinel ratio of approximately 100, with skeletal olivine phenocrysts and small (<50 μm) spinel crystals that tend to be spatially associated with the olivine phenocrysts. The large number of spinel crystals included within olivine phenocrysts is thought to be due to skeletal olivine phenocrysts coming into physical contact with spinel by synneusis during the chaotic conditions of ascent and extrusion. A second group of samples tend to have large olivine phenocrysts relatively free of included spinel, a few large (>100 μm) spinel crystals that show evidence of two stages of growth, and a volume ratio of olivine to spinel of 100 to well over 1000. The olivine and spinel in this group have crystallized more slowly with little physical interaction, and show evidence that they have accumulated in a magma chamber.

On geological interpretations of crystal size distributions: Constant vs. proportionate growth

USGS Publications Warehouse

Eberl, D.D.; Kile, D.E.; Drits, V.A.

2002-01-01

Geological interpretations of crystal size distributions (CSDs) depend on understanding the crystal growth laws that generated the distributions. Most descriptions of crystal growth, including a population-balance modeling equation that is widely used in petrology, assume that crystal growth rates at any particular time are identical for all crystals, and, therefore, independent of crystal size. This type of growth under constant conditions can be modeled by adding a constant length to the diameter of each crystal for each time step. This growth equation is unlikely to be correct for most mineral systems because it neither generates nor maintains the shapes of lognormal CSDs, which are among the most common types of CSDs observed in rocks. In an alternative approach, size-dependent (proportionate) growth is modeled approximately by multiplying the size of each crystal by a factor, an operation that maintains CSD shape and variance, and which is in accord with calcite growth experiments. The latter growth law can be obtained during supply controlled growth using a modified version of the Law of Proportionate Effect (LPE), an equation that simulates the reaction path followed by a CSD shape as mean size increases.

The bipolar filaments formed by herpes simplex virus type 1 SSB/recombination protein (ICP8) suggest a mechanism for DNA annealing.

PubMed

Makhov, Alexander M; Sen, Anindito; Yu, Xiong; Simon, Martha N; Griffith, Jack D; Egelman, Edward H

2009-02-20

Herpes simplex virus type 1 encodes a multifunctional protein, ICP8, which serves both as a single-strand binding protein and as a recombinase, catalyzing reactions involved in replication and recombination of the viral genome. In the presence of divalent ions and at low temperature, previous electron microscopic studies showed that ICP8 will form long left-handed helical filaments. Here, electron microscopic image reconstruction reveals that the filaments are bipolar, with an asymmetric unit containing two subunits of ICP8 that constitute a symmetrical dimer. This organization of the filament has been confirmed using scanning transmission electron microscopy. The pitch of the filaments is approximately 250 A, with approximately 6.2 dimers per turn. Docking of a crystal structure of ICP8 into the reconstructed filament shows that the C-terminal domain of ICP8, attached to the body of the subunit by a flexible linker containing approximately 10 residues, is packed into a pocket in the body of a neighboring subunit in the crystal in a similar manner as in the filament. However, the interactions between the large N-terminal domains are quite different in the filament from that observed in the crystal. A previously proposed model for ICP8 binding single-stranded DNA (ssDNA), based upon the crystal structure, leads to a model for a continuous strand of ssDNA near the filament axis. The bipolar nature of the ICP8 filaments means that a second strand of ssDNA would be running through this filament in the opposite orientation, and this provides a potential mechanism for how ICP8 anneals complementary ssDNA into double-stranded DNA, where each strand runs in opposite directions.

Refined crystal structure of DsRed, a red fluorescent protein from coral, at 2.0-A resolution.

PubMed

Yarbrough, D; Wachter, R M; Kallio, K; Matz, M V; Remington, S J

2001-01-16

The crystal structure of DsRed, a red fluorescent protein from a corallimorpharian, has been determined at 2.0-A resolution by multiple-wavelength anomalous dispersion and crystallographic refinement. Crystals of the selenomethionine-substituted protein have space group P2(1) and contain a tetramer with 222 noncrystallographic symmetry in the asymmetric unit. The refined model has satisfactory stereochemistry and a final crystallographic R factor of 0.162. The protein, which forms an obligatory tetramer in solution and in the crystal, is a squat rectangular prism comprising four protomers whose fold is extremely similar to that of the Aequorea victoria green fluorescent protein despite low ( approximately 23%) amino acid sequence homology. The monomer consists of an 11-stranded beta barrel with a coaxial helix. The chromophores, formed from the primary sequence -Gln-Tyr-Gly- (residues 66-68), are arranged in a approximately 27 x 34-A rectangular array in two approximately antiparallel pairs. The geometry at the alpha carbon of Gln-66 (refined without stereochemical restraints) is consistent with an sp(2) hybridized center, in accord with the proposal that red fluorescence is because of an additional oxidation step that forms an acylimine extension to the chromophore [Gross, L. A., Baird, G. S., Hoffman, R. C., Baldridge, K. K. & Tsien, R. Y. (2000) Proc. Natl. Acad. Sci. USA 87, 11990-11995]. The carbonyl oxygen of Phe-65 is almost 90 degrees out of the plane of the chromophore, consistent with theoretical calculations suggesting that this is the minimum energy conformation of this moiety despite the conjugation of this group with the rest of the chromophore.

Calculation of the Energy-Band Structure of the Kronig-Penney Model Using the Nearly-Free and Tightly-Bound-Electron Approximations

ERIC Educational Resources Information Center

Wetsel, Grover C., Jr.

1978-01-01

Calculates the energy-band structure of noninteracting electrons in a one-dimensional crystal using exact and approximate methods for a rectangular-well atomic potential. A comparison of the two solutions as a function of potential-well depth and ratio of lattice spacing to well width is presented. (Author/GA)

The effect of an infinite plane-wave approximation on calculations for second-harmonic generation in a one-dimensional nonlinear crystal

NASA Astrophysics Data System (ADS)

Zhao, Jing; Zhao, Li-Ming

2012-05-01

In this paper, the second-harmonic generation (SHG) in a one-dimensional nonlinear crystal that is embedded in air is investigated. Previously, the identical configuration was studied in Li Z. Y. et al., Phys. Rev. B, 60 (1999) 10644, without the use of the slowly varying amplitude approximation (SVAA), but by adopting the infinite plane-wave approximation (PWA), despite the fact that this approximation is not quite applicable to such a system. We calculate the SHG conversion efficiency without a PWA, and compare the results with those from the quoted reference. The investigation reveals that conversion efficiencies of SHG as calculated by the two methods appear to exhibit significant differences, and that the SHG may be modulated by the field of a fundamental wave (FW). The ratio between SHG conversion efficiencies as produced by the two methods shows a periodic variation, and this oscillatory behavior is fully consistent with the variation in transmittance of the FW. Quasi-phase matching (QPM) is also studied, and we find that the location of the peak for SHG conversion efficiency deviates from Δd=0, which differs from the conventional QPM results.

A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag.

PubMed

Dean, Philip A W; Craig, Don; Dance, Ian; Russell, Vanessa; Scudder, Marcia

2004-01-26

Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single crystals, this reversible dehydration-hydration occurs without visually evident crystal change, but with loss of mechanical strength. We postulate a general mechanism for transport of water molecules along the channels, associated with local partial collapses of the channel framework, with concomitant bending but little breaking of the host Ag-O and Cr-O bonds, which is readily reversed.

Purification, crystallization and preliminary X-ray analysis of aminoglycoside-2′′-phosphotransferase-Ic [APH(2′′)-Ic] from Enterococcus gallinarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byrnes, Laura J.; Badarau, Adriana; Vakulenko, Sergei B.

2008-02-01

APH(2′′)-Ic is an enzyme that is responsible for high-level gentamicin resistance in E. gallinarum isolates. Crystals of the wild-type enzyme and three mutants have been prepared and a complete X-ray diffraction data set was collected to 2.15 Å resolution from an F108L crystal. Bacterial resistance to aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, aminoglycoside-2′′-phosphotransferase-Ic [APH(2′′)-Ic] from Enterococcus gallinarum, has been cloned and the wild-type protein (comprising 308 amino-acid residues) and threemore » mutants that showed elevated minimum inhibitory concentrations towards gentamicin (F108L, H258L and a double mutant F108L/H258L) were expressed in Escherichia coli and subsequently purified. All APH(2′′)-Ic variants were crystallized in the presence of 14–20%(w/v) PEG 4000, 0.25 M MgCl{sub 2}, 0.1 M Tris–HCl pH 8.5 and 1 mM Mg{sub 2}GTP. The crystals belong to the monoclinic space group C2, with one molecule in the asymmetric unit. The approximate unit-cell parameters are a = 82.4, b = 54.2, c = 77.0 Å, β = 108.8°. X-ray diffraction data were collected to approximately 2.15 Å resolution from an F108L crystal at beamline BL9-2 at SSRL, Stanford, California, USA.« less

Ignition and growth modeling of detonation reaction zone experiments on single crystals of PETN and HMX

NASA Astrophysics Data System (ADS)

White, Bradley W.; Tarver, Craig M.

2017-01-01

It has long been known that detonating single crystals of solid explosives have much larger failure diameters than those of heterogeneous charges of the same explosive pressed or cast to 98 - 99% theoretical maximum density (TMD). In 1957, Holland et al. demonstrated that PETN single crystals have failure diameters of about 8 mm, whereas heterogeneous PETN charges have failure diameters of less than 0.5 mm. Recently, Fedorov et al. quantitatively determined nanosecond time resolved detonation reaction zone profiles of single crystals of PETN and HMX by measuring the interface particle velocity histories of the detonating crystals and LiF windows using a PDV system. The measured reaction zone time durations for PETN and HMX single crystal detonations were approximately 100 and 260 nanoseconds, respectively. These experiments provided the necessary data to develop Ignition and Growth (I&G) reactive flow model parameters for the single crystal detonation reaction zones. Using these parameters, the calculated unconfined failure diameter of a PETN single crystal was 7.5 +/- 0.5 mm, close to the 8 mm experimental value. The calculated failure diameter of an unconfined HMX single crystal was 15 +/- 1 mm. The unconfined failure diameter of an HMX single crystal has not yet been determined precisely, but Fedorov et al. detonated 14 mm diameter crystals confined by detonating a HMX-based plastic bonded explosive (PBX) without initially overdriving the HMX crystals.

Solution Growth of a Novel Nonlinear Optical Material: L-Histidine Tetrafluoroborate

NASA Technical Reports Server (NTRS)

Aggarwal, M. D.; Choi, J.; Wang, W. S.; Bhat, K.; Lal, R. B.; Shields, Angela D.; Penn, Benjamin G.; Frazier, Donald O.

1998-01-01

Single crystals of L-Histidine tetrafluoroborate (L-HFB), a semiorganic nonlinear optical (NLO) material have been successfully grown by the temperature lowering and evaporation methods in our laboratory. Solubility curves of L-HFB have been determined in different solvents, such as water, ethanol and acetone. The solubility of L-HFB is very low in acetone, and ethanol, therefore, it is not feasible to grow L-HFB single crystals using these solvents. Good quality single crystals of a novel nonlinear optical material L-HFB have been grown from aqueous solution. Effects of seed orientation on morphologies of L-HFB crystals were studied. The advantages and disadvantage of both the evaporation and the temperature lowering techniques are compared. The single crystals in size 20 x 20 x 10 cubic mm were grown with deionized water as solvent in two weeks with an approximate growth rate of 1.4mm/day. The transmission range for these crystals has been found to be from 250 nm to 1500 nm.

The mechanical properties of as-grown noncubic organic molecular crystals assessed by nanoindentation

DOE PAGES

Taw, Matthew R.; Yeager, John D.; Hooks, Daniel E.; ...

2017-06-19

Organic molecular crystals are often noncubic and contain significant steric hindrance within their structure to resist dislocation motion. Plastic deformation in these systems can be imparted during processing (tableting and comminution of powders), and the defect density impacts subsequent properties and performance. This paper measured the elastic and plastic properties of representative monoclinic, orthorhombic, and triclinic molecular crystalline structures using nanoindentation of as-grown sub-mm single crystals. The variation in modulus due to in-plane rotational orientation, relative to a Berkovich tip, was approximately equal to the variation of a given crystal at a fixed orientation. The onset of plasticity occurs consistentlymore » at shear stresses between 1 and 5% of the elastic modulus in all three crystal systems, and the hardness to modulus ratio suggests conventional Berkovich tips do not generate fully self-similar plastic zones in these materials. Finally, this provides guidance for mechanical models of tableting, machining, and property assessment of molecular crystals.« less

Duration of a Magma Ocean and Subsequent Mantle Overturn in Mars: Evidence from Nakhlites

NASA Technical Reports Server (NTRS)

Debaille, V.; Brandon, A. D.; Yin, Q.-Z.; Jacobsen, B.

2008-01-01

It is now generally accepted that the heat produced by accretion, short-lived radioactive elements such as Al-26, and gravitational energy from core formation was sufficient to at least partially melt the silicate portions of terrestrial planets resulting in a global-scale magma ocean. More particularly, in Mars, the geochemical signatures displayed by shergottites, are likely inherited from the crystallization of this magma ocean. Using the short-lived chronometer Sm-146 - Nd-142 (t(sup 1/2) = 103 Myr), the duration of the Martian magma ocean (MMO) has been evaluated to being less than 40 Myr, while recent and more precise ND-142/ND-144 data were used to evaluate the longevity of the MMO to approximately 100 Myr after the solar system formation. In addition, it has been proposed that the end of the crystallization of the MMO may have triggered a mantle overturn, as a result of a density gradient in the cumulate layers crystallized at different levels. Dating the mantle overturn could hence provide additional constraint on the duration of the MMO. Among SNC meteorites, nakhlites are characterized by high epsilon W-182 of approximately +3 and an epsilon Nd-142 similar to depleted shergottites of +0.6-0.9. It has hence been proposed that the source of nakhlites was established very early in Mars history (approximately 8-10 Myr). However, the times recorded in HF-182-W-182 isotope system, i.e. when 182Hf became effectively extinct (approximately 50 Myr after solar system formation) are less than closure times recorded in the Sm-146-Nd-142 isotope system (with a full coverage of approximately 500 Myr after solar system formation). This could result in decoupling between the present-day measured epsilon W-182 and epsilon Nd-142 as the SM-146 may have recorded later differentiation events in epsilon ND-142 not observed in epsilon W-182 values. With these potential complexities in short-lived chronological data for SNC's in mind, new Hf-176/Hf-177, Nd-143/Nd-144 and Nd-142/Nd-144 were obtained for three nakhlites (Nakhla, MIL03346 and Yamato000593). These new data are combined with previous epsilon W-182 data, to investigate potential discrepancies between the Hf-182-W-182 and Sm-146-Nd-142 systematics, and the relationship between the source of nakhlites and a crystallizing magma ocean

An Optically Isotropic Antiferroelectric Liquid Crystal (OI-AFLC) Display Mode Operating over a Wide Temperature Range using Ternary Bent-Core Liquid Crystal Mixtures

DOE PAGES

Bergquist, Leah; Zhang, Cuiyu; Ribeiro de Almeida, Roberta R.; ...

2017-02-07

Here, we report on the synthesis and characterization of bent-core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI-AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmC aP A phase down to below -40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterizedmore » and their liquid crystal as well as electro-optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy, and electro-optical tests.« less

Electro-optical modulator in a polymerinfiltrated silicon slotted photonic crystal waveguide heterostructure resonator.

PubMed

Wülbern, Jan Hendrik; Petrov, Alexander; Eich, Manfred

2009-01-05

We present a novel concept of a compact, ultra fast electro-optic modulator, based on photonic crystal resonator structures that can be realized in two dimensional photonic crystal slabs of silicon as core material employing a nonlinear optical polymer as infiltration and cladding material. The novel concept is to combine a photonic crystal heterostructure cavity with a slotted defect waveguide. The photonic crystal lattice can be used as a distributed electrode for the application of a modulation signal. An electrical contact is hence provided while the optical wave is kept isolated from the lossy metal electrodes. Thereby, well known disadvantages of segmented electrode designs such as excessive scattering are avoided. The optical field enhancement in the slotted region increases the nonlinear interaction with an external electric field resulting in an envisaged switching voltage of approximately 1 V at modulation speeds up to 100 GHz.

Thermal stresses in the laser disc from a tetragonal c-cut crystal

NASA Astrophysics Data System (ADS)

Yumashev, K. V.; Loiko, P. A.

2014-12-01

Analytical expressions for thermal stresses and strains, as well as displacements, are obtained for the laser disc from a tetragonal crystal cut along the [0 0 1] axis under plane stress approximation, for the first time, to our knowledge. This study illustrates that, in polar coordinates, the normal stresses, σr and σθ, are angular independent, while the shear one τrθ is zero. The thermal strains, εr and εθ, and displacements, u and υ, depend on both radial and tangential coordinates; this dependence has the shape of a four-leaf rose. For considered crystal cutting with isotropic in-plane thermal expansion, the displacements are not pure radial (υ≠0). The values of stresses, strains and displacements are calculated for the disc from a c-cut yttrium vanadate laser crystal, Nd:YVO4. The thermal fracture issues are analyzed for this crystal.

An Optically Isotropic Antiferroelectric Liquid Crystal (OI-AFLC) Display Mode Operating over a Wide Temperature Range using Ternary Bent-Core Liquid Crystal Mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bergquist, Leah; Zhang, Cuiyu; Ribeiro de Almeida, Roberta R.

Here, we report on the synthesis and characterization of bent-core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI-AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmC aP A phase down to below -40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterizedmore » and their liquid crystal as well as electro-optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy, and electro-optical tests.« less

Imperfection and radiation damage in protein crystals studied with coherent radiation

PubMed Central

Nave, Colin; Sutton, Geoff; Evans, Gwyndaf; Owen, Robin; Rau, Christoph; Robinson, Ian; Stuart, David Ian

2016-01-01

Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage. PMID:26698068

Specific Adsorption of Osteopontin and Synthetic Polypeptides to Calcium Oxalate Monohydrate Crystals

PubMed Central

Taller, Adam; Grohe, Bernd; Rogers, Kem A.; Goldberg, Harvey A.; Hunter, Graeme K.

2007-01-01

Protein-crystal interactions are known to be important in biomineralization. To study the physicochemical basis of such interactions, we have developed a technique that combines confocal microscopy of crystals with fluorescence imaging of proteins. In this study, osteopontin (OPN), a protein abundant in urine, was labeled with the fluorescent dye AlexaFluor-488 and added to crystals of calcium oxalate monohydrate (COM), the major constituent of kidney stones. In five to seven optical sections along the z axis, scanning confocal microscopy was used to visualize COM crystals and fluorescence imaging to map OPN adsorbed to the crystals. To quantify the relative adsorption to different crystal faces, fluorescence intensity was measured around the perimeter of the crystal in several sections. Using this method, it was shown that OPN adsorbs with high specificity to the edges between {100} and {121} faces of COM and much less so to {100}, {121}, or {010} faces. By contrast, poly-L-aspartic acid adsorbs preferentially to {121} faces, whereas poly-L-glutamic acid adsorbs to all faces approximately equally. Growth of COM in the presence of rat bone OPN results in dumbbell-shaped crystals. We hypothesize that the edge-specific adsorption of OPN may be responsible for the dumbbell morphology of COM crystals found in human urine. PMID:17496021

Estimating the Aqueous Solubility of Pharmaceutical Hydrates

PubMed Central

Franklin, Stephen J.; Younis, Usir S.; Myrdal, Paul B.

2016-01-01

Estimation of crystalline solute solubility is well documented throughout the literature. However, the anhydrous crystal form is typically considered with these models, which is not always the most stable crystal form in water. In this study an equation which predicts the aqueous solubility of a hydrate is presented. This research attempts to extend the utility of the ideal solubility equation by incorporating desolvation energetics of the hydrated crystal. Similar to the ideal solubility equation, which accounts for the energetics of melting, this model approximates the energy of dehydration to the entropy of vaporization for water. Aqueous solubilities, dehydration and melting temperatures, and log P values were collected experimentally and from the literature. The data set includes different hydrate types and a range of log P values. Three models are evaluated, the most accurate model approximates the entropy of dehydration (ΔSd) by the entropy of vaporization (ΔSvap) for water, and utilizes onset dehydration and melting temperatures in combination with log P. With this model, the average absolute error for the prediction of solubility of 14 compounds was 0.32 log units. PMID:27238488

Turbulence in the ionized gas of the Orion nebula

NASA Astrophysics Data System (ADS)

Arthur, S. J.; Medina, S.-N. X.; Henney, W. J.

2016-12-01

In order to study the nature, origin, and impact of turbulent velocity fluctuations in the ionized gas of the Orion nebula, we apply a variety of statistical techniques to observed velocity cubes. The cubes are derived from high resolving power (R ≈ 40 000) longslit spectroscopy of optical emission lines that span a range of ionizations. From velocity channel analysis (VCA), we find that the slope of the velocity power spectrum is consistent with predictions of Kolmogorov theory between scales of 8 and 22 arcsec (0.02 to 0.05 pc). The outer scale, which is the dominant scale of density fluctuations in the nebula, approximately coincides with the autocorrelation length of the velocity fluctuations that we determine from the second-order velocity structure function. We propose that this is the principal driving scale of the turbulence, which originates in the autocorrelation length of dense cores in the Orion molecular filament. By combining analysis of the non-thermal linewidths with the systematic trends of velocity centroid versus ionization, we find that the global champagne flow and smaller scale turbulence each contribute in equal measure to the total velocity dispersion, with respective root-mean-square widths of 4-5 km s-1. The turbulence is subsonic and can account for only one half of the derived variance in ionized density, with the remaining variance provided by density gradients in photoevaporation flows from globules and filaments. Intercomparison with results from simulations implies that the ionized gas is confined to a thick shell and does not fill the interior of the nebula.

Crystal structure of 2-diazo-imidazole-4,5-dicarbo-nitrile.

PubMed

Parrish, Damon A; Kramer, Stephanie; Windler, G Kenneth; Chavez, David E; Leonard, Philip W

2015-07-01

In the title compound, C5N6, all the atoms are approximately coplanar. In the crystal, mol-ecules are packed with short contact distances of 2.885 (2) (between the diazo N atom connected to the ring and a cyano N atom on a neighboring mol-ecule) and 3.012 (2) Å (between the terminal diazo N atom and an N atom of a neighboring imidazole ring).

Characterisation of longitudinal variation in photonic crystal fibre

NASA Astrophysics Data System (ADS)

Francis-Jones, Robert J. A.; Mosley, Peter J.

2016-10-01

We present a method by which the degree of longitudinal variation in photonic crystal fibre (PCF) may be characterised through seeded four-wave mixing (FWM). Using an iterative numerical reconstruction, we created a model PCF that displays similar FWM phasematching properties across all measured length scales. Our results demonstrate that the structure of our PCF varies by less than 1% and that the characteristic length of the variations is approximately 15 cm.

Thin film modeling of crystal dissolution and growth in confinement.

PubMed

Gagliardi, Luca; Pierre-Louis, Olivier

2018-01-01

We present a continuum model describing dissolution and growth of a crystal contact confined against a substrate. Diffusion and hydrodynamics in the liquid film separating the crystal and the substrate are modeled within the lubrication approximation. The model also accounts for the disjoining pressure and surface tension. Within this framework, we obtain evolution equations which govern the nonequilibrium dynamics of the crystal interface. Based on this model, we explore the problem of dissolution under an external load, known as pressure solution. We find that in steady state, diverging (power-law) crystal-surface repulsions lead to flat contacts with a monotonic increase of the dissolution rate as a function of the load. Forces induced by viscous dissipation then surpass those due to disjoining pressure at large enough loads. In contrast, finite repulsions (exponential) lead to sharp pointy contacts with a dissolution rate independent of the load and the liquid viscosity. Ultimately, in steady state, the crystal never touches the substrate when pressed against it. This result is independent from the nature of the crystal-surface interaction due to the combined effects of viscosity and surface tension.

Thin film modeling of crystal dissolution and growth in confinement

NASA Astrophysics Data System (ADS)

Gagliardi, Luca; Pierre-Louis, Olivier

2018-01-01

We present a continuum model describing dissolution and growth of a crystal contact confined against a substrate. Diffusion and hydrodynamics in the liquid film separating the crystal and the substrate are modeled within the lubrication approximation. The model also accounts for the disjoining pressure and surface tension. Within this framework, we obtain evolution equations which govern the nonequilibrium dynamics of the crystal interface. Based on this model, we explore the problem of dissolution under an external load, known as pressure solution. We find that in steady state, diverging (power-law) crystal-surface repulsions lead to flat contacts with a monotonic increase of the dissolution rate as a function of the load. Forces induced by viscous dissipation then surpass those due to disjoining pressure at large enough loads. In contrast, finite repulsions (exponential) lead to sharp pointy contacts with a dissolution rate independent of the load and the liquid viscosity. Ultimately, in steady state, the crystal never touches the substrate when pressed against it. This result is independent from the nature of the crystal-surface interaction due to the combined effects of viscosity and surface tension.

Multiparametric Detection of Antibodies against Different EBV Antigens to Predict Risk for Nasopharyngeal Carcinoma in a High-Risk Population of China.

PubMed

Chen, Hao; Chen, Shulin; Lu, Jie; Wang, Xueping; Li, Jianpei; Li, Linfang; Fu, Jihuan; Scheper, Thomas; Meyer, Wolfgang; Peng, Yu-Hui; Liu, Wanli

2017-09-01

In this study, we aimed to use the combined detection of multiple antibodies against Epstein-Barr virus (EBV) antigens to develop a model for screening and diagnosis of nasopharyngeal carcinoma (NPC). Samples of 300 nasopharyngeal carcinoma patients and 494 controls, including 294 healthy subjects (HC), 99 non-nasopharyngeal carcinoma cancer patients (NNPC), and 101 patients with benign nasopharyngeal lesions (BNL), were incubated with the EUROLINE Anti-EBV Profile 2, and band intensities were used to establish a risk prediction model. The nasopharyngeal carcinoma risk probability analysis based on the panel of VCAgp125 IgA, EBNA-1 IgA, EA-D IgA, EBNA-1 IgG, EAD IgG, and VCAp19 IgG displayed the best performance. When using 26.1% as the cutoff point in ROC analysis, the AUC value and sensitivity/specificity were 0.951 and 90.7%/86.2%, respectively, in nasopharyngeal carcinoma and all controls. In nasopharyngeal carcinoma and controls without the non-nasopharyngeal carcinoma and BNL groups, the AUC value and sensitivity/specificity were 0.957 and 90.7%/88.1%, respectively. The diagnostic specificity and sensitivity of the EUROLINE Anti-EBV Profile 2 assay for both nasopharyngeal carcinoma and early-stage nasopharyngeal carcinoma were higher than that of mono-antibody detection by immune-enzymatic assay and real-time PCR (EBV DNA). In the VCA-IgA-negative group, 82.6% of nasopharyngeal carcinoma patients showed high probability for nasopharyngeal carcinoma, and the negative predictive value was 97.1%. In the VCA-IgA-positive group, 73.3% of healthy subjects showed low probability. The positive predictive value reached 98.2% in this group. The nasopharyngeal carcinoma risk probability value determined by the EUROLINE Anti-EBV Profile 2 might be a suitable tool for nasopharyngeal carcinoma screening. Cancer Prev Res; 10(9); 542-50. ©2017 AACR . ©2017 American Association for Cancer Research.

Prevalence and molecular profiling of Epstein Barr virus (EBV) among healthy blood donors from different nationalities in Qatar

PubMed Central

Smatti, Maria K.; Yassine, Hadi M.; AbuOdeh, Raed; AlMarawani, Asmaa; Taleb, Sara A.; Althani, Asmaa A.

2017-01-01

Background The Epstein–Barr virus (EBV) is the causative agent of infectious mononucleosis. EBV is highly prevalent lymphotropic herpesvirus and has been linked to several malignancies. Transmission is generally by oral secretions, but can be through blood transfusions and organ transplantations. This study aimed to determine the seroprevalence, viremia rates, and circulating genotypes of EBV in healthy blood donors in Qatar. Methods Blood samples from 673 blood donors of different nationalities residing in Qatar (mainly Qatar, Egypt, Syria, Jordan, Pakistan, and India) were collected and tested for anti-EBV capsid (VCA; IgG & IgM), nuclear (EBNA; IgG), and early (EA-D; IgG) antigens. Avidity testing was determined when active infection was suspected. DNA was extracted from the buffy coat and subjected to EBV-DNA quantification using qRT-PCR. Genotyping was performed using nested-PCR targeting EBV-EBNA2 gene, and phylogeny by sequence analysis of the LMP-1 gene. Results 97.9% (673/659) of the samples were seropositive as indicated by the presence VCA-IgG, while 52.6% (354/673) had detectible EBV-DNA. EBV seroprevalence and viremia rates increased significantly with age. Genotyping of 51 randomly selected samples showed predominance of Genotype 1 (72.5%, 37/51) as compared to genotype 2 (3.5%), and mixed infections were detected in 4% of the samples. Sub-genotyping for these samples revealed that the Mediterranean strain was predominant (65.3%), followed by B95.8 prototype and North Carolina strains (12.2% each), and China1 strain (6%). Conclusion As a first study to evaluate EBV infection in highly diverse population in Qatar, where expatriates represent more than 85% of the population, our results indicated high seroprevalence and viremia rate of EBV in different nationalities, with genotype 1 and Mediterranean strain being predominant. Clinical significance of these finding have not been investigated and shall be evaluated in future studies. PMID:29228016

Prevalence and molecular profiling of Epstein Barr virus (EBV) among healthy blood donors from different nationalities in Qatar.

PubMed

Smatti, Maria K; Yassine, Hadi M; AbuOdeh, Raed; AlMarawani, Asmaa; Taleb, Sara A; Althani, Asmaa A; Nasrallah, Gheyath K

2017-01-01

The Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis. EBV is highly prevalent lymphotropic herpesvirus and has been linked to several malignancies. Transmission is generally by oral secretions, but can be through blood transfusions and organ transplantations. This study aimed to determine the seroprevalence, viremia rates, and circulating genotypes of EBV in healthy blood donors in Qatar. Blood samples from 673 blood donors of different nationalities residing in Qatar (mainly Qatar, Egypt, Syria, Jordan, Pakistan, and India) were collected and tested for anti-EBV capsid (VCA; IgG & IgM), nuclear (EBNA; IgG), and early (EA-D; IgG) antigens. Avidity testing was determined when active infection was suspected. DNA was extracted from the buffy coat and subjected to EBV-DNA quantification using qRT-PCR. Genotyping was performed using nested-PCR targeting EBV-EBNA2 gene, and phylogeny by sequence analysis of the LMP-1 gene. 97.9% (673/659) of the samples were seropositive as indicated by the presence VCA-IgG, while 52.6% (354/673) had detectible EBV-DNA. EBV seroprevalence and viremia rates increased significantly with age. Genotyping of 51 randomly selected samples showed predominance of Genotype 1 (72.5%, 37/51) as compared to genotype 2 (3.5%), and mixed infections were detected in 4% of the samples. Sub-genotyping for these samples revealed that the Mediterranean strain was predominant (65.3%), followed by B95.8 prototype and North Carolina strains (12.2% each), and China1 strain (6%). As a first study to evaluate EBV infection in highly diverse population in Qatar, where expatriates represent more than 85% of the population, our results indicated high seroprevalence and viremia rate of EBV in different nationalities, with genotype 1 and Mediterranean strain being predominant. Clinical significance of these finding have not been investigated and shall be evaluated in future studies.

A systematic analysis of the in vitro and in vivo functions of the HD-GYP domain proteins of Vibrio cholerae.

PubMed

McKee, Robert W; Kariisa, Ankunda; Mudrak, Benjamin; Whitaker, Courtney; Tamayo, Rita

2014-10-25

The second messenger cyclic diguanylate (c-di-GMP) plays a central role in bacterial adaptation to extracellular stimuli, controlling processes such as motility, biofilm development, cell development and, in some pathogens, virulence. The intracellular level of c-di-GMP is controlled by the complementary activities of diguanylate cyclases containing a GGDEF domain and two classes of c-di-GMP phosphodiesterases containing an EAL or HD-GYP hydrolytic domain. Compared to the GGDEF and EAL domains, the functions of HD-GYP domain family proteins are poorly characterized. The human diarrheal pathogen Vibrio cholerae encodes nine putative HD-GYP domain proteins. To determine the contributions of HD-GYP domain proteins to c-di-GMP signaling in V. cholerae, we systematically analyzed the enzymatic functionality of each protein and their involvement in processes known to be regulated by c-di-GMP: motility, biofilm development and virulence. Complementary in vitro and in vivo experiments showed that four HD-GYP domain proteins are active c-di-GMP phosphodiesterases: VC1295, VC1348, VCA0210 and VCA0681. Mutation of individual HD-GYP domain genes, as well as combinatorial mutations of multiple HD-GYP domain genes, had no effect on motility or biofilm formation of V. cholerae under the conditions tested. Furthermore, no single HD-GYP domain gene affected intestinal colonization by V. cholerae in an infant mouse model. However, inactivation of multiple HD-GYP domain genes, including the four encoding functional phosphodiesterases, significantly attenuated colonization. These results indicate that the HD-GYP family of c-di-GMP phosphodiesterases impacts signaling by this second messenger during infection. Altogether, this work greatly furthers the understanding of this important family of c-di-GMP metabolic enzymes and demonstrates a role for HD-GYP domain proteins in the virulence of V. cholerae.

Crystal structure of the 28 kDa glutathione S-transferase from Schistosoma haematobium.

PubMed

Johnson, Kenneth A; Angelucci, Francesco; Bellelli, Andrea; Hervé, Maxime; Fontaine, Josette; Tsernoglou, Demetrious; Capron, André; Trottein, François; Brunori, Maurizio

2003-09-02

Schistomiasis is a debilitating parasitic disease which affects 200 million people, causing life-threatening complications in 10% of the patients. This paper reports the crystal structure of the Schistosoma haematobium 28 kDa glutathione S-transferase, a multifunctional enzyme involved in host-parasite interactions and presently considered as a promising vaccine candidate against schistosomiasis. The structures of the GSH-free enzyme, as well as the partially (approximately 40%) and almost fully (approximately 80%) GSH-saturated enzyme, exhibit a unique feature, absent in previous GST structures, concerning the crucial and invariant Tyr10 side chain which occupies two alternative positions. The canonical conformer, which allows an H-bond to be formed between the side chain hydroxyl group and the activated thiolate of GSH, is somewhat less than 50% occupied. The new conformer, with the phenoxyl ring on the opposite side of the mobile loop connecting strand 1 and helix 1, is stabilized by a polar interaction with the guanidinium group of the conserved Arg21 side chain. The presence of two conformers of Tyr10 may provide a clue about clarifying the multiple catalytic functions of Sh28GST and might prove to be relevant for the design of specific antischistosomal drugs. The K(d) for GSH binding was determined by equilibrium fluorescence titrations to be approximately 3 microM and by stopped-flow rapid mixing experiments to be approximately 9 microM. The relatively tight binding of GSH by Sh28GST explains the residually bound GSH in the crystal and supports a possible role of GSH as a tightly bound cofactor involved in the catalytic mechanism for prostaglandin D(2) synthase activity.

Preliminary Results from Pyroelectric Crystal Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Tom; Edwards, Ronald; Bright, Kevin

The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. Cadets in the Department of Physics and Nuclear Engineering at USMA are using pyroelectric crystals to ionize and accelerate residual gas trapped inside a vacuum system. A system using two lithium tantalate crystals with associated diagnostics was designed and is now operational. X-ray energies of approximately 150 keV have been achieved. Future work will focus on developing a portable neutron generator using the D-D nuclearmore » fusion process.« less

Optical properties of B12P2 crystals: Ab initio calculation and EELS

NASA Astrophysics Data System (ADS)

Reshetniak, V. V.; Mavrin, B. N.; Medvedev, V. V.; Perezhogin, I. A.; Kulnitskiy, B. A.

2018-05-01

We report an experimental and theoretical investigation of the electronic structure and optical properties of B12P2 crystals in the energy range up to 60 eV. Experimental studies are performed by the method of electron energy loss spectroscopy, and theoretical studies are carried out using density functional theory and the GW approximation. The calculated dependence of the energy loss function is in agreement with the experiment. Based on the results of the calculations, we determine the optical properties of B12P2 crystals and investigate their anisotropy. The dispersion and density of electronic states are calculated and analyzed.

Single-crystal sapphire microstructure for high-resolution synchrotron X-ray monochromators

DOE PAGES

Asadchikov, Victor E.; Butashin, Andrey V.; Buzmakov, Alexey V.; ...

2016-03-22

We report on the growth and characterization of several sapphire single crystals for the purpose of x-ray optics applications. Structural defects were studied by means of laboratory double-crystal X-ray diffractometry and white beam synchrotron-radiation topography. The investigations confirmed that the main defect types are dislocations. The best quality crystal was grown using the Kyropoulos technique with a dislocation density of 10 2-10 3 cm -2 and a small area with approximately 2*2 mm 2 did not show dislocation contrast in many reflections and has suitable quality for application as a backscattering monochromator. As a result, a clear correlation between growthmore » rate and dislocation density is observed, though growth rate is not the only parameter impacting the quality.« less

The Load Capability of Piezoelectric Single Crystal Actuators

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing; Su, Ji; Jiang, Xiaoning; Rehrig, Paul W.; Hackenberger, Wesley S.

2006-01-01

Piezoelectric lead magnesium niobate-lead titanate (PMN-PT) single crystal is one of the most promising materials for electromechanical device applications due to its high electrical field induced strain and high electromechanical coupling factor. PMN-PT single crystal-based multilayer stack actuators and multilayer stack-based flextensional actuators have exhibited high stroke and high displacement-voltage ratios. The actuation capabilities of these two actuators were evaluated using a newly developed method based upon a laser vibrometer system under various loading conditions. The measured displacements as a function of mechanical loads at different driving voltages indicate that the displacement response of the actuators is approximately constant under broad ranges of mechanical load. The load capabilities of these PMN-PT single crystal-based actuators and the advantages of the capability for applications will be discussed.

The Load Capability of Piezoelectric Single Crystal Actuators

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing; Su, Ji; Jiang, Xiaoning; Rehrig, Paul W.; Hackenberger, Wesley S.

2007-01-01

Piezoelectric lead magnesium niobate-lead titanate (PMN-PT) single crystal is one of the most promising materials for electromechanical device applications due to its high electrical field induced strain and high electromechanical coupling factor. PMN-PT single crystal-based multilayer stack actuators and multilayer stack-based flextensional actuators have exhibited high stroke and high displacement-voltage ratios. The actuation capabilities of these two actuators were evaluated using a newly developed method based upon a laser vibrometer system under various loading conditions. The measured displacements as a function of mechanical loads at different driving voltages indicate that the displacement response of the actuators is approximately constant under broad ranges of mechanical load. The load capabilities of these PMN-PT single crystal-based actuators and the advantages of the capability for applications will be discussed.

Dielectric constant adjustments in computations of the scattering properties of solid ice crystals using the Generalized Multi-particle Mie method

NASA Astrophysics Data System (ADS)

Lu, Yinghui; Aydin, Kültegin; Clothiaux, Eugene E.; Verlinde, Johannes

2014-03-01

Ice crystal scattering properties at microwave radar wavelengths can be modeled with the Generalized Multi-particle Mie (GMM) method by decomposing an ice crystal into a cluster of tiny spheres composed of solid ice. In this decomposition the mass distribution of the tiny spheres in the cluster is no longer equivalent to that in the original ice crystal because of gaps between the tiny spheres. To compensate for the gaps in the cluster representation of an ice crystal in the GMM computation of crystal scattering properties, the Maxwell Garnett approximation is used to estimate what the dielectric function of the tiny spheres (i.e., the inclusions) in the cluster must be to make the cluster of tiny spheres with associated air gaps (i.e., the background matrix) dielectrically equivalent to the original solid ice crystal. Overall, compared with the T-matrix method for spheroids outside resonance regions this approach agrees to within mostly 0.3 dB (and often better) in the horizontal backscattering cross section σhh and the ratio of horizontal and vertical backscattering cross sections σhh/σvv, and 6% for the amplitude scattering matrix elements Re{S22-S11} and Im{S22} in the forward direction. For crystal sizes and wavelengths near resonances, where the scattering parameters are highly sensitive to the crystal shape, the differences are generally within 1.2 dB for σhh and σhh/σvv, 20% for Re{S22-S11} and 6% for Im{S22}. The Discrete Dipole Approximation (DDA) results for the same spheroids are generally closer than those of GMM to the T-matrix results. For hexagonal plates the differences between GMM and the DDA at a W-band wavelength (3.19 mm) are mostly within 0.6 dB for σhh, 1 dB for σhh/σvv, 11% for Re{S22-S11} and 12% for Im{S22}. For columns the differences are within 0.3 dB for σhh and σhh/σvv, 8% for Re{S22-S11} and 4% for Im{S22}. This method shows higher accuracy than an alternative method that artificially increases the thickness of ice plates to provide the same mass as the original ice crystal.

Polyacrylamide hydrogels: an effective tool for delivering liquid baits to pest ants (Hymenoptera: Formicidae).

PubMed

Buczkowski, Grzegorz; Roper, Elray; Chin, Darren

2014-04-01

Ant management in urban and natural areas often relies on toxic baits. Liquid baits are highly attractive to pest ants because they mimic natural food sources such as honeydew and nectar, the principal dietary components of many ants. However, liquid bait use has been limited owing to the lack of bait dispensers that are effective, inexpensive, and easy to service. The current study evaluated the potential of water-storing crystals (polyacrylamide spheres) to effectively deliver liquid thiamethoxam baits to laboratory colonies of Argentine ants, Linepithema humile Mayr. Results of laboratory trials show that bait crystals saturated in 25% sucrose solution containing 0.007% thiamethoxam are highly attractive to Argentine ants and highly effective against all castes and life stages, including workers, queens, and brood. Fresh bait crystals were highly effective and required approximately 2 d to kill all workers and approximately 6 d to achieve complete mortality in queens and brood. Results of bait aging tests show that the crystals lose approximately 70% of moisture in 8 h and the duration of outdoor exposure has a significant effect on moisture loss and subsequently bait acceptance and bait efficacy. A gradual decrease in mortality was observed for all castes and life stages as bait age increased. In general, fresh baits and those aged for < 8 h retained their efficacy and caused substantial mortality. Baits aged longer than 8 h were substantially less attractive and less effective. Horizontal transfer tests examined the transfer of thiamethoxam from live treated donors to live untreated recipients. The results show that donor ants that obtain thiamethoxam by feeding on bait crystals effectively transfer it to untreated recipient ants. The level of secondary mortality depended on the donor:recipient ratio, with approximately 40% recipient worker mortality with the 1:5 ratio and 15% recipient worker mortality with 1:10 or 1:20 ratios. However, no queens died in any transfer tests, suggesting that multiple feedings from multiple donors may be necessary to produce queen mortality. The results of the transfer tests demonstrate the role of trophallaxis in the distribution of thiamethoxam and confirm that thiamethoxam is effectively transferred in Argentine ant colonies. The distribution of thiamethoxam within Argentine ant colonies was further examined using protein marking coupled with an enzyme-linked immunosorbent assay to detect the marker. The distribution of thiamethoxam was highly efficient, with 79 +/- 13% of workers testing positive at 15 min and 100 +/- 0% of workers testing positive at 6 h. In summary, the results of this study demonstrate that water-storing crystals effectively deliver thiamethoxam to all castes and life stages of Argentine ants and may offer an effective tool for Argentine ant management.

Measurable characteristics of lysozyme crystal growth

NASA Technical Reports Server (NTRS)

Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

2005-01-01

The behavior of protein crystal growth is estimated from measurements performed at both the microscopic and molecular levels. In the absence of solutal flow, it was determined that a model that balances the macromolecular flux toward the crystal surface with the flux of the crystal surface well characterizes crystal growth observed using microscopic methods. Namely, it was determined that the model provides accurate estimates for the crystal-growth velocities upon evaluation of crystal-growth measurements obtained in time. Growth velocities thus determined as a function of solution supersaturation were further interpreted using established deterministic models. From analyses of crystal-growth velocities, it was found that the mode of crystal growth varies with respect to increasing solution supersaturation, possibly owing to kinetic roughening. To verify further the hypothesis of kinetic roughening, crystal growth at the molecular level was examined using atomic force microscopy (AFM). From the AFM measurements, it was found that the magnitude of surface-height fluctuations, h(x), increases with increasing solution supersaturation. In contrast, the estimated characteristic length, xi, decreases rapidly upon increasing solution supersaturation. It was conjectured that the magnitude of both h(x) and xi could possibly determine the mode of crystal growth. Although the data precede any exact theory, the non-critical divergence of h(x) and xi with respect to increasing solution supersaturation was nevertheless preliminarily established. Moreover, approximate models to account for behavior of both h(x) and xi are also presented.

Chromium Recharging Processes in the Y3Al5O12: Mg, Cr Single Crystal under the Reducing and Oxidizing Annealing Influence

DTIC Science & Technology

2001-01-01

approximately 0.2% of total number of chromium ions occupied tetrahedral sites forming phototropic centers in the YAG: Mg, Cr crystal. Keywords: yttrium...aluminium garnet, Cr doping, thermal treatment, phototropic centers, optical characterization, electron paramagnetic resonance. 1. INTRODUCTION An...of garnet structure while the main part of chromium occupies octahedral sites in three-valence state. 10-12 The dependence of amount of phototropic

Silicon crystals: Process for manufacturing wafer-like silicon crystals with a columnar structure

NASA Technical Reports Server (NTRS)

Authier, B.

1978-01-01

Wafer-like crystals suitable for making solar cells are formed by pouring molten Si containing suitable dopants into a mold of the desired shape and allowing it to solidify in a temperature gradient, whereby the large surface of the melt in contact with the mold is kept at less than 200 D and the free surface is kept at a temperature of 200-1000 D higher, but below the melting point of Si. The mold can also be made in the form of a slit, whereby the 2 sides of the mold are kept at different temperatures. A mold was milled in the surface of a cylindrical graphite block 200 mm in diameter. The granite block was induction heated and the bottom of the mold was cooled by means of a water-cooled Cu plate, so that the surface of the mold in contact with one of the largest surfaces of the melt was held at approximately 800 D. The free surface of the melt was subjected to thermal radiation from a graphite plate located 2 mm from the surface and heated to 1500 D. The Si crystal formed after slow cooling to room temperature had a columnar structure and was cut with a diamond saw into wafers approximately 500 mm thick. Solar cells prepared from these wafers had efficiencies of 10 to 11%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moddeman, W.E.; Foose, D.S.; Bowling, W.C.

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface chemistry of three BORAZON* materials: Type I, 510, and 550. Samples were examined in the ``as-received`` condition and following heat treatments in air. Boron oxides were found on the Type I and 550 BORAZON crystals; oxide thicknesses were estimated to be 15A. The titanium-coated product, 510, was found to have a discontinuous titanium coating with a TiO{sub 2} layer that was approximately 20A thick. Following heat treatment at 800{degrees}C for 1 hr in air, the boron oxide layer on the Type I crystals was foundmore » to increase in thickness to approximately 30A. The same heat treatment on the 510 crystals yielded a multi-layered structure consisting of an enriched outer layer of B{sub 2}O{sub 3} over a predominantly TiO{sub 2} one. The entire initial titanium coating was oxidized, and segregated patches of B{sub 2}O{sub 3} (``islands``) were observed. The segregated patches can be explained in terms of the coalescence of liquid B{sub 2}O{sub 3} (melting point = 450{degrees}C). The 550 crystals were oxidized at 500{degrees}C. The oxide formed at this temperature was B{sub x}O (x > 0.67). These results were interpreted in terms of their potential use in sealing BORAZON to glass in vitreous bonding.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moddeman, W.E.; Foose, D.S.; Bowling, W.C.

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface chemistry of three BORAZON* materials: Type I, 510, and 550. Samples were examined in the as-received'' condition and following heat treatments in air. Boron oxides were found on the Type I and 550 BORAZON crystals; oxide thicknesses were estimated to be 15A. The titanium-coated product, 510, was found to have a discontinuous titanium coating with a TiO{sub 2} layer that was approximately 20A thick. Following heat treatment at 800{degrees}C for 1 hr in air, the boron oxide layer on the Type I crystals was foundmore » to increase in thickness to approximately 30A. The same heat treatment on the 510 crystals yielded a multi-layered structure consisting of an enriched outer layer of B{sub 2}O{sub 3} over a predominantly TiO{sub 2} one. The entire initial titanium coating was oxidized, and segregated patches of B{sub 2}O{sub 3} ( islands'') were observed. The segregated patches can be explained in terms of the coalescence of liquid B{sub 2}O{sub 3} (melting point = 450{degrees}C). The 550 crystals were oxidized at 500{degrees}C. The oxide formed at this temperature was B{sub x}O (x > 0.67). These results were interpreted in terms of their potential use in sealing BORAZON to glass in vitreous bonding.« less

Purification, Crystallization And Preliminary X-Ray Analysis of Aminoglycoside-2 ''-Phosphotransferase-Ic [APH(2 '')-Ic] From Enterococcus Gallinarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byrnes, L.J.; /SLAC, SSRL; Badarau, A.

2009-04-30

Bacterial resistance to aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, aminoglycoside-2{double_prime}-phosphotransferase-Ic [APH(2{double_prime})-Ic] from Enterococcus gallinarum, has been cloned and the wild-type protein (comprising 308 amino-acid residues) and three mutants that showed elevated minimum inhibitory concentrations towards gentamicin (F108L, H258L and a double mutant F108L/H258L) were expressed in Escherichia coli and subsequently purified. All APH(2{double_prime})-Ic variants were crystallized in the presence of 14-20%(w/v) PEG 4000, 0.25 M MgCl{sub 2}, 0.1 M Tris-HClmore » pH 8.5 and 1 mM Mg{sub 2}GTP. The crystals belong to the monoclinic space group C2, with one molecule in the asymmetric unit. The approximate unit-cell parameters are a = 82.4, b = 54.2, c = 77.0 {angstrom}, {beta} = 108.8{sup o}. X-ray diffraction data were collected to approximately 2.15 {angstrom} resolution from an F108L crystal at beamline BL9-2 at SSRL, Stanford, California, USA.« less

Crystal growth and magnetic characterization of a tetragonal polymorph of NiNb2O6

NASA Astrophysics Data System (ADS)

Munsie, T. J. S.; Millington, A.; Dube, P. A.; Dabkowska, H. A.; Britten, J.; Luke, G. M.; Greedan, J. E.

2016-04-01

A previously unidentified polymorph of nickel niobate, NiNb2O6, was grown and stabilized in single crystalline form using an optical floating zone furnace. Key parameters of the growth procedure involved use of a slight excess of NiO (1.2% by mol), an O2 atmosphere and a growth rate of 25 mm/h. The resulting boule consisted of a polycrystalline exterior shell of the columbite structure - columbite is the thermodynamically stable form of NiNb2O6 under ambient conditions - and a core region consisting of transparent yellow-green single crystals up to 5 mm×2 mm×1 mm in dimension of the previously unidentified phase. The crystal structure, solved from single crystal x-ray diffraction data, is described in the P42/n space group. Interestingly, this is not a subgroup of P42/mnm, the rutile space group. The Ni2+ ions form layers which are displaced such that interlayer magnetic frustration is anticipated. Magnetic susceptibility data shows a broad maximum at approximately 22 K and evidence for long range antiferromagnetic order at approximately 14 K, obtained by Fisher heat capacity analysis as well as heat capacity measurements. The susceptibility data for T > 25 K are well fit by a square lattice S = 1 model, consistent with the Ni sublattice topology.

Shock Pressures, Temperatures and Durations in L Chondrites: Constraints from Shock-Vein Mineralogy

NASA Astrophysics Data System (ADS)

Xie, Z.; Aramovish Weaver, C.; Decarli, P. S.; Sharp, T. G.

2003-12-01

Shock effects in meteorites provide a record of major impact events on meteorite parent bodies. Shock veins in chondrites, which result from local melting during shock loading, are the location of all high-pressure minerals. Shock veins contain igneous assemblages, produced by the crystallization of shock-induced melt, and metamorphic assemblages, produced by solid-state transformation in entrained host-rock clasts and wall rock. The mineralogy, distribution of high-pressure minerals and microstructures in shock veins provide a record of crystallization pressures and quench histories that can be used to constrain shock pressures and pulse duration. Here we report mineralogical and microstructural studies of shock-induced melt veins in L chondrites that provide insight into the impact history of the L-chondrite parent body. Eight L6 chondrites were investigated using FESEM and TEM and Raman spectroscopy: RC 106 (S6), Tenham (S6), Umbarger (S4-S6), Roy (S3-S5), Ramsdorf (S4), Kunashak (S4), Nakhon Pathon (S4) and La Lande (S4). Igneous melt-vein assemblages, combined with published phase equilibrium data (Agee et al. 1996), indicate crystallization pressures from less than 2.5 GPa for Kunashack and LaLande to approximately 25 GPa for Tenham. Because shock veins quench primarily by thermal conduction, crystallization starts at vein edges and progresses inward. Variation in the igneous assemblage across shock veins, combined with thermal modelling, provides constraints on quench times and pressure variation during quench. Most samples appear to have crystallized prior to shock release, whereas Kunashack and LaLande apparently crystallized after pressure release. RC 106 and Tenham (both S6), which have thick melt veins with uniform igneous assemblages, crystallized under equilibrium shock pressures of approximately 22-25 GPa during shock events that lasted at least 500 ms and 50ms, respectively. The fact that S6 samples do not appear to have crystallized at a pressures greater than about 25 GPa, suggest that the impacts that produced shock veins in chondrites had low relative impact velocities.

Fluorescence Studies of Protein Crystal Nucleation

NASA Technical Reports Server (NTRS)

Pusey, Marc L.

1999-01-01

Fluorescence can be used to study protein crystal nucleation through methods such as anisotropy, quenching, and resonance energy transfer (FRET), to follow pH and ionic strength changes, and follow events occurring at the growth interface. We have postulated, based upon a range of experimental evidence that the growth unit of tetragonal hen egg white lysozyme is an octamer. Several fluorescent derivatives of chicken egg white lysozyme have been prepared. The fluorescent probes lucifer yellow (LY), cascade blue, and 5-((2-aminoethyl)aminonapthalene-1-sulfonic acid (EDANS), have been covalently attached to ASP 101. All crystallize in the characteristic tetragonal form, indicating that the bound probes are likely laying within the active site cleft. Crystals of the LY and EDANS derivatives have been found to diffract to at least 1.7 A. A second group of derivatives is to the N-terminal amine group, and these do not crystallize as this site is part of the contact region between the adjacent 43 helix chains. However derivatives at these sites would not interfere with formation of the 43 helices in solution. Preliminary FRET studies have been carried out using N-terminal bound pyrene acetic acid (Ex 340 nm, Em 376 nm) lysozyme as a donor and LY (Ex -425 nm, Em 525 nm) labeled lysozyme as an acceptor. FRET data have been obtained at pH 4.6, 0.1 M NaAc buffer, at 5 and 7% NaCl, 4 C. The corresponding Csat values are 0.471 and 0.362 mg/ml (approximately 3.3 and approximately 2.5 x 10(exp -5) M respectively). The data at both salt concentrations show a consistent trend of decreasing fluorescence intensity of the donor species (PAA) with increasing total protein concentration. This decrease is more pronounced at 7% NaCl, consistent with the expected increased intermolecular interactions at higher salt concentrations reflected in the lower solubility. The calculated average distance between any two protein molecules at 5 x 10(exp -6) M is approximately 70nm, well beyond the range where any FRET can be expected. Results from these and ongoing studies will be presented.

Light scattering by a nematic liquid crystal droplet: Wentzel–Kramers–Brillouin approximation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.; Miskevich, A. A.

2016-01-15

Light scattering by an optically anisotropic liquid crystal (LC) droplet of a nematic in an isotropic polymer matrix is considered in the Wentzel–Kramers–Brillouin (WKB) approximation. General relations are obtained for elements of the amplitude matrix of light scattering by a droplet of arbitrary shape and for the structure of the director field. Analytic expressions for the amplitude matrices are derived for spherical LC droplets with a uniformly oriented structure of local optical axes for strictly forward and strictly backward scattering. The efficiency factors of extinction and backward scattering for a spherical nonabsorbing LC droplet depending on the LC optical anisotropy,more » refractive index of the polymer, illumination conditions, and orientation of the optical axis of the droplet are analyzed. Verification of the obtained solutions has been performed.« less

Evaluation of structural vacancies for 1/1-Al-Re-Si approximant crystals by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Yamada, K.; Suzuki, H.; Kitahata, H.; Matsushita, Y.; Nozawa, K.; Komori, F.; Yu, R. S.; Kobayashi, Y.; Ohdaira, T.; Oshima, N.; Suzuki, R.; Takagiwa, Y.; Kimura, K.; Kanazawa, I.

2018-01-01

The size of structural vacancies and structural vacancy density of 1/1-Al-Re-Si approximant crystals with different Re compositions were evaluated by positron annihilation lifetime and Doppler broadening measurements. Incident positrons were found to be trapped at the monovacancy-size open space surrounded by Al atoms. From a previous analysis using the maximum entropy method and Rietveld method, such an open space is shown to correspond to the centre of Al icosahedral clusters, which locates at the vertex and body centre. The structural vacancy density of non-metallic Al73Re17Si10 was larger than that of metallic Al73Re15Si12. The observed difference in the structural vacancy density reflects that in bonding nature and may explain that in the physical properties of the two samples.

Nanocrystalline CuInS2 And CuInSe2 via Low-Temperature Pyrolysis Of Single-Source Molecular Precursors

NASA Technical Reports Server (NTRS)

Castro, Stephanie L.; Bailey, Sheila G.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Hepp, Aloysius F.

2002-01-01

Single-source precursors are molecules which contain all the necessary elements for synthesis of a desired material. Thermal decomposition of the precursor results in the formation of the material with the correct stoichiometry, as a nanocrystalline powder or a thin film. Nanocrystalline materials hold potential as components of next-generation Photovoltaic (PV) devices. Presented here are the syntheses of CuInS2 and CuInSe2 nanocrystals from the precursors (PPh3)2CuIn(SEt)4 and (PPh3)2CuIn(SePh)4, respectively. The size of the nanocrystals varies with the reaction temperature; a minimum of 200 C is required for the formation of the smallest CuInS2 crystals (approximately 1.6 nm diameter); at 300 C, crystals are approximately 7 nm.

Cumulant Green's function calculations of plasmon satellites in bulk sodium: Influence of screening and the crystal environment

NASA Astrophysics Data System (ADS)

Zhou, Jianqiang Sky; Gatti, Matteo; Kas, J. J.; Rehr, J. J.; Reining, Lucia

2018-01-01

We present ab initio calculations of the photoemission spectra of bulk sodium using different flavors of the cumulant expansion approximation for the Green's function. In particular, we study the dispersion and intensity of the plasmon satellites. We show that the satellite spectrum is much more sensitive to many details than the quasiparticle spectrum, which suggests that the experimental investigation of satellites could yield additional information beyond the usual studies of the band structure. In particular, a comparison to the homogeneous electron gas shows that the satellites are influenced by the crystal environment, although the crystal potential in sodium is weak. Moreover, the temperature dependence of the lattice constant is reflected in the position of the satellites. Details of the screening also play an important role; in particular, the contribution of transitions from 2 s and 2 p semicore levels influences the satellites, but not the quasiparticle. Moreover, inclusion of contributions to the screening beyond the random-phase approximation has an effect on the satellites. Finally, we elucidate the importance of the coupling of electrons and holes by comparing the results of the time-ordered and the retarded cumulant expansion approximations. Again, we find small but noticeable differences. Since all the small effects add up, our most advanced calculation yields a satellite position which is improved with respect to previous calculations by almost 1 eV. This stresses the fact that the calculation of satellites is much more delicate than the calculation of a quasiparticle band structure.

Retrieving cirrus microphysical properties from stellar aureoles

NASA Astrophysics Data System (ADS)

DeVore, J. G.; Kristl, J. A.; Rappaport, S. A.

2013-06-01

The aureoles around stars caused by thin cirrus limit nighttime measurement opportunities for ground-based astronomy, but can provide information on high-altitude ice crystals for climate research. In this paper we attempt to demonstrate quantitatively how this works. Aureole profiles can be followed out to ~0.2° from stars and ~0.5° from Jupiter. Interpretation of diffracted starlight is similar to that for sunlight, but emphasizes larger particles. Stellar diffraction profiles are very distinctive, typically being approximately flat out to a critical angle followed by gradually steepening power-law falloff with slope less steep than -3. Using the relationship between the phase function for diffraction and the average Fourier transform of the projected area of complex ice crystals, we show that defining particle size in terms of average projected area normal to the propagation direction of the starlight leads to a simple, analytic approximation representing large-particle diffraction that is nearly independent of crystal habit. A similar analytic approximation for the diffraction aureole allows it to be separated from the point spread function and the sky background. Multiple scattering is deconvolved using the Hankel transform leading to the diffraction phase function. Application of constrained numerical inversion to the phase function then yields a solution for the particle size distribution in the range between ~50 μm and ~400 μm. Stellar aureole measurements can provide one of the very few, as well as least expensive, methods for retrieving cirrus microphysical properties from ground-based observations.

Theory of the intermediate stage of crystal growth with applications to insulin crystallization

NASA Astrophysics Data System (ADS)

Barlow, D. A.

2017-07-01

A theory for the intermediate stage of crystal growth, where two defining equations one for population continuity and another for mass-balance, is used to study the kinetics of the supersaturation decay, the homogeneous nucleation rate, the linear growth rate and the final distribution of crystal sizes for the crystallization of bovine and porcine insulin from solution. The cited experimental reports suggest that the crystal linear growth rate is directly proportional to the square of the insulin concentration in solution for bovine insulin and to the cube of concentration for porcine. In a previous work, it was shown that the above mentioned system could be solved for the case where the growth rate is directly proportional to the normalized supersaturation. Here a more general solution is presented valid for cases where the growth rate is directly proportional to the normalized supersaturation raised to the power of any positive integer. The resulting expressions for the time dependent normalized supersaturation and crystal size distribution are compared with experimental reports for insulin crystallization. An approximation for the maximum crystal size at the end of the intermediate stage is derived. The results suggest that the largest crystal size in the distribution at the end of the intermediate stage is maximized when nucleation is restricted to be only homogeneous. Further, the largest size in the final distribution depends only weakly upon the initial supersaturation.

Maintenance of supersaturation I: indomethacin crystal growth kinetic modeling using an online second-derivative ultraviolet spectroscopic method.

PubMed

Patel, Dhaval D; Joguparthi, Vijay; Wang, Zeren; Anderson, Bradley D

2011-07-01

Formulations that produce supersaturated solutions after their oral administration have received increased attention as a means to improve bioavailability of poorly water-soluble drugs. Although it is widely recognized that excipients can prolong supersaturation, the mechanisms by which these beneficial effects are realized are generally unknown. Difficulties in separately measuring the kinetics of nucleation and crystal growth have limited progress in understanding the mechanisms by which excipients contribute to the supersaturation maintenance. This paper describes the crystal growth kinetic modeling of indomethacin, a poorly water-soluble drug, from supersaturated aqueous suspensions using a newly developed, online second-derivative ultraviolet spectroscopic method. The apparent indomethacin equilibrium solubility after crystal growth at a high degree of supersaturation (S=6) was approximately 55% higher than the indomethacin equilibrium solubility determined prior to growth, which was attributed to the deposition of a higher energy indomethacin form on the seed crystals. The indomethacin crystal growth kinetics (S=6) was of first order. By comparing the mass transfer coefficients from indomethacin dissolution and crystal growth, it was shown that the indomethacin crystal growth kinetics at S=6 was bulk diffusion controlled. The change in indomethacin seed crystal size distribution before and after crystal growth was determined and modeled using a mass-balance relationship. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

Infrared study of OH(-) defects in KTiOPO4 crystals

NASA Astrophysics Data System (ADS)

Morris, P. A.; Crawford, M. K.; Jones, B.

1992-12-01

Variations in the concentrations and distributions of the OH(-) defects present in flux and hydrothermal KTiOPO4 (KTP) crystals, measured by infrared spectroscopy of single crystals, are attributed to differences in the growth environments and other nonhydrogenic defects present in the crystals. The concentrations of OH(-) have been estimated from the infrared data to be approximately 400 ppma (parts per million atomic) (3.0 x 10 exp 19/cu cm) in the flux crystals, 1100-1500 ppma (0.74-1.1 x 10 exp 20/cu cm) in the high-temperature hydrothermal and 600 ppma (4.3 x 10 exp 19/cu cm) in the low-temperature hydrothermal crystals. A 3566/cm peak and a 3575/cm band are observed in all crystals. The integrated intensity of the OH(-) absorption band at 3566/cm increases at the expense of the 3575/cm band at higher temperatures in the high-temperature hydrothermal crystals. Several OH(-) peaks (3490, 3455, 3428, 3420, and 3333/cm), which have strongly temperature-dependent linewidths, are present in the hydrothermally grown KTP crystals. The temperature dependencies of their peak frequencies and widths are consistent with the presence of mobile protons in the lattice. The protons located in the 3490 and 3428/cm sites are believed to contribute to the ionic conductivity of the high-conductivity high-temperature hydrothermal crystals.

Trapped Atoms in One-Dimensional Photonic Crystals

DTIC Science & Technology

2013-08-09

a single silicon -nitride nanobeam (refractive index n = 2) with a 1D array of filleted rectangular holes along the propagation direction; atoms are...trapped in the centers of the holes (figure 1( a )). The second waveguide consists of two parallel silicon nitride nanobeams, each with a periodic array...the refractive index of silicon nitride is approximately constant across the optical domain, we adopt the approximation based on a frequency

Estimating proportions in petrographic mixing equations by least-squares approximation.

PubMed

Bryan, W B; Finger, L W; Chayes, F

1969-02-28

Petrogenetic hypotheses involving fractional crystallization, assimilation, or mixing of magmas may be expressed and tested as problems in leastsquares approximation. The calculation uses all of the data and yields a unique solution for each model, thus avoiding the ambiguity inherent in graphical or trial-and-error procedures. The compositional change in the 1960 lavas of Kilauea Volcano, Hawaii, is used to illustrate the method of calculation.

Is it Possible to have the Similar Unit Cell in Crystals of Different form from the same Macromolecule? (A Case Study of Ribosome Crystals)

NASA Technical Reports Server (NTRS)

Karpova, E. A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Three different types of ribosome crystals were grown by the vapor diffusion technique in hanging drops as described in (1,2). The ribosome is a large asymmetric RNA-protein complex (2.3 million Da), which is protein syntheses machinery of the cell. In this poster we would like to discuss the features of ribosome crystallization. Ribosomes were purified from the thermophilic bacteria Thermus thermophilus by centrifugation (3). Three types of crystals (needle, flat tetragonal and tetragonal-like pyramid) can be grown from the same solution; furthermore, in the same drop using 10-15% 2-methyl-2,4- pentanediol as a precipitant. The crystals appeared in 5-48 hours. The crystals were stable and can co-exist in solution over long period of time. The kinetics of appearance of different crystal forms was different: first the needle crystals were grown, then the tetragonal, and finally the tetragonal pyramids. Later studies of the process of ribosome crystal growth depending on supersaturation showed that low supersaturation results in the appearance of tetragonal plates or tetragonal-like pyramids. An electron microscopy study, together with computer modeling, has shown that crystals of different forms have a high probability of having the same unit cell parameters. According to these experiments the following conclusion can be dranvn: the level of supersaturation of the macromolecule in a crystallizing solution is one of the major factors for forming three-dimensional crystals convenient for X-rays diffraction analysis. From the same macromolecule solution, crystals of different forms can be grown at approximately the same conditions by varying the concentration of macromolecule in the solution. Ion-macromolecule and water-macromolecule interactions, apparently, play the main role in the formation of the unit cell of the crystals.

A study of waste liquid crystal display generation in mainland China.

PubMed

Liu, Zhifeng; Xu, Zeying; Huang, Haihong; Li, Bingbing

2016-01-01

The generation of liquid crystal display waste is becoming a serious social problem. Predicting liquid crystal display waste status is the foundation for establishing a recycling network; however, the difficulty in predicting liquid crystal display waste quantity lies in data mining. In order to determine the quantity and the distribution of liquid crystal display waste in China, the four top-selling liquid crystal display products (liquid crystal display TVs, desktop PCs, notebook PCs, and mobile phones) were selected as study objects. Then, the extended logistic model and market supply A method was used to predict the quantity of liquid crystal display waste products. Moreover, the distribution of liquid crystal display waste products in different regions was evaluated by examining the consumption levels of household equipment. The results revealed that the quantity of waste liquid crystal displays would increase rapidly in the next decade. In particular, the predicted quantity of waste liquid crystal displays would rise to approximately 4.262 × 10(9) pieces in 2020, and the total display area (i.e. the surface area of liquid crystal display panels) of waste liquid crystal displays would reach 5.539 × 10(7) m(2). The prediction on the display area of waste liquid crystal display TVs showed that it would account for 71.5% of the total display area by 2020. Meanwhile, the quantity of waste mobile phones would significantly grow, increasing 5.8 times from 2012 to 2020. In terms of distribution, Guangdong is the top waste liquid crystal display-generating province in China, followed by Jiangsu, Shandong, Henan, Zhejiang, and Sichuan. Considering its regional characteristics, Guangdong has been proposed to be the most important location of the recycling network. © The Author(s) 2015.

Anhydrous crystals of DNA bases are wide gap semiconductors.

PubMed

Maia, F F; Freire, V N; Caetano, E W S; Azevedo, D L; Sales, F A M; Albuquerque, E L

2011-05-07

We present the structural, electronic, and optical properties of anhydrous crystals of DNA nucleobases (guanine, adenine, cytosine, and thymine) found after DFT (Density Functional Theory) calculations within the local density approximation, as well as experimental measurements of optical absorption for powders of these crystals. Guanine and cytosine (adenine and thymine) anhydrous crystals are predicted from the DFT simulations to be direct (indirect) band gap semiconductors, with values 2.68 eV and 3.30 eV (2.83 eV and 3.22 eV), respectively, while the experimentally estimated band gaps we have measured are 3.83 eV and 3.84 eV (3.89 eV and 4.07 eV), in the same order. The electronic effective masses we have obtained at band extremes show that, at low temperatures, these crystals behave like wide gap semiconductors for electrons moving along the nucleobases stacking direction, while the hole transport are somewhat limited. Lastly, the calculated electronic dielectric functions of DNA nucleobases crystals in the parallel and perpendicular directions to the stacking planes exhibit a high degree of anisotropy (except cytosine), in agreement with published experimental results.

Coercivity enhancement of Dy-coated Nd-Fe-B flakes by crystallization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukunaga, H.; Sugimoto, Y.; Nakano, M.

2011-04-01

The coercivity of isotropic Dy-coated Nd-Fe-B flakes was enhanced by crystallization and simultaneous diffusion of Dy from their surfaces. Amorphous Dy-coated Nd-Fe-B flakes were crystallized by heating them to 923 K 2over a 2 min period followed by rapid cooling. During crystallization, the Dy on the surface diffused into the flakes. This low-temperature rapid annealing produced flakes with fine grains and the Dy diffusion enhanced their coercivity. The coercivity after crystallization increased with increasing Dy layer thickness, although the remanence decreased when the layer thickness exceeded 3 {mu}m. Thick coatings of over 6 {mu}m resulted in the formation of DyFe{submore » 2}, which degraded the magnetic properties of the crystallized flakes. Flakes with a 3-{mu}m-thick coating exhibited excellent magnetic properties after annealing: They had a coercivity of 1880 kA/m and a remanence of 78 emu/g. This coercivity is approximately 500 kA/m higher than that of uncoated flakes, whereas the remanence is comparable to that of uncoated flakes.« less

Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

PubMed Central

Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

2017-01-01

Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities. PMID:28338074

Accelerated Physical Stability Testing of Amorphous Dispersions.

PubMed

Mehta, Mehak; Suryanarayanan, Raj

2016-08-01

The goal was to develop an accelerated physical stability testing method of amorphous dispersions. Water sorption is known to cause plasticization and may accelerate drug crystallization. In an earlier investigation, it was observed that both the increase in mobility and decrease in stability in amorphous dispersions was explained by the "plasticization" effect of water (Mehta et al. Mol. Pharmaceutics 2016, 13 (4), 1339-1346). In this work, the influence of water concentration (up to 1.8% w/w) on the correlation between mobility and crystallization in felodipine dispersions was investigated. With an increase in water content, the α-relaxation time as well as the time for 1% w/w felodipine crystallization decreased. The relaxation times of the systems, obtained with different water concentration, overlapped when the temperature was scaled (Tg/T). The temperature dependencies of the α-relaxation time as well as the crystallization time were unaffected by the water concentration. Thus, the value of the coupling coefficient, up to a water concentration of 1.8% w/w, was approximately constant. Based on these findings, the use of "water sorption" is proposed to build predictive models for crystallization in slow crystallizing dispersions.

Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

NASA Astrophysics Data System (ADS)

Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

2017-03-01

Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

Rapid electrostatics-assisted layer-by-layer assembly of near-infrared-active colloidal photonic crystals.

PubMed

Askar, Khalid; Leo, Sin-Yen; Xu, Can; Liu, Danielle; Jiang, Peng

2016-11-15

Here we report a rapid and scalable bottom-up technique for layer-by-layer (LBL) assembling near-infrared-active colloidal photonic crystals consisting of large (⩾1μm) silica microspheres. By combining a new electrostatics-assisted colloidal transferring approach with spontaneous colloidal crystallization at an air/water interface, we have demonstrated that the crystal transfer speed of traditional Langmuir-Blodgett-based colloidal assembly technologies can be enhanced by nearly 2 orders of magnitude. Importantly, the crystalline quality of the resultant photonic crystals is not compromised by this rapid colloidal assembly approach. They exhibit thickness-dependent near-infrared stop bands and well-defined Fabry-Perot fringes in the specular transmission and reflection spectra, which match well with the theoretical calculations using a scalar-wave approximation model and Fabry-Perot analysis. This simple yet scalable bottom-up technology can significantly improve the throughput in assembling large-area, multilayer colloidal crystals, which are of great technological importance in a variety of optical and non-optical applications ranging from all-optical integrated circuits to tissue engineering. Copyright © 2016 Elsevier Inc. All rights reserved.

Theoretical studies of the electronic properties of ceramic materials

NASA Astrophysics Data System (ADS)

Ching, W. Y.

1990-11-01

The first-principles orthogonalized linear combination of atomic orbitals (OLCAO) method for electronic structure studies has been applied to a variety of complex inorganic crystals. The theory and the practice of the OLCAO method in the local density approximation are discussed in detail. Recent progress in the study of electronic and optical properties of a large list of ceramic systems are summarized. Eight selected topics on different ceramic crystals focusing on specific points of interest are presented as examples. The materials discussed are AlN, Cu2O, beta-Si3N4, Y2O3, LiB3O5, ferroelectric crystals, Fe-B compounds, and the YBa2Cu3O7 superconductor.

Left-right correlation in coupled F-center defects.

PubMed

Janesko, Benjamin G

2016-08-07

This work explores how left-right correlation, a textbook problem in electronic structure theory, manifests in a textbook example of electrons trapped in crystal defects. I show that adjacent F-center defects in lithium fluoride display symptoms of "strong" left-right correlation, symptoms similar to those seen in stretched H2. Simulations of UV/visible absorption spectra qualitatively fail to reproduce experiment unless left-right correlation is taken into account. This is of interest to both the electronic structure theory and crystal-defect communities. Theorists have a new well-behaved system to test their methods. Crystal-defect groups are cautioned that the approximations that successfully model single F-centers may fail for adjacent F-centers.

Measurement of beam profiles by terahertz sensor card with cholesteric liquid crystals.

PubMed

Tadokoro, Yuzuru; Nishikawa, Tomohiro; Kang, Boyoung; Takano, Keisuke; Hangyo, Masanori; Nakajima, Makoto

2015-10-01

We demonstrate a sensor card with cholesteric liquid crystals (CLCs) for terahertz (THz) waves generated from a nonlinear crystal pumped by a table-top laser. A beam profile of the THz waves is successfully visualized as color change by the sensor card without additional electronic devices, power supplies, and connecting cables. Above the power density of 4.3  mW/cm2, the approximate beam diameter of the THz waves is measured using the hue image that is digitalized from the picture of the sensor card. The sensor card is low in cost, portable, and suitable for various situations such as THz imaging and alignment of THz systems.

Outer-sphere Pb(II) adsorbed at specific surface sites on single crystal α-alumina

USGS Publications Warehouse

Bargar, John R.; Towle, Steven N.; Brown, Gordon E.; Parks, George A.

1996-01-01

Solvated Pb(II) ions were found to adsorb as structurally well-defined outer-sphere complexes at specific sites on the α-Al2O3 (0001) single crystal surface, as determined by grazing-incidence X-ray absorption fine structure (GI-XAFS) measurements. The XAFS results suggest that the distance between Pb(II) adions and the alumina surface is approximately 4.2 Å. In contrast, Pb(II) adsorbs as more strongly bound inner-sphere complexes on α-Al2O3 (102). The difference in reactivities of the two alumina surfaces has implications for modeling surface complexation reactions of contaminants in natural environments, catalysis, and compositional sector zoning of oxide crystals.

Luminescence of BaBrI and SrBrI single crystals doped with Eu2+

NASA Astrophysics Data System (ADS)

Shalaev, A. A.; Shendrik, R.; Myasnikova, A. S.; Bogdanov, A.; Rusakov, A.; Vasilkovskyi, A.

2018-05-01

The crystal growth procedure and luminescence properties of pure and Eu2+-doped BaBrI and SrBrI crystals are reported. Emission and excitation spectra were recorded under ultraviolet and vacuum ultraviolet excitations. The energy of the first Eu2+ 4f-5d transition and SrBrI band gap are obtained. The electronic structure calculations were performed within GW approximation as implemented in the Vienna Ab Initio Simulation Package. The energy between lowest Eu2+ 5d state and the bottom of conduction band are found based on luminescence quenching parameters. The vacuum referred binding energy diagram of lanthanide levels was constructed using the chemical shift model.

Deterministic Bragg Coherent Diffraction Imaging.

PubMed

Pavlov, Konstantin M; Punegov, Vasily I; Morgan, Kaye S; Schmalz, Gerd; Paganin, David M

2017-04-25

A deterministic variant of Bragg Coherent Diffraction Imaging is introduced in its kinematical approximation, for X-ray scattering from an imperfect crystal whose imperfections span no more than half of the volume of the crystal. This approach provides a unique analytical reconstruction of the object's structure factor and displacement fields from the 3D diffracted intensity distribution centred around any particular reciprocal lattice vector. The simple closed-form reconstruction algorithm, which requires only one multiplication and one Fourier transformation, is not restricted by assumptions of smallness of the displacement field. The algorithm performs well in simulations incorporating a variety of conditions, including both realistic levels of noise and departures from ideality in the reference (i.e. imperfection-free) part of the crystal.

Crystal growth of LiIn 1–xGa xSe 2 crystals

DOE PAGES

Wiggins, Brenden; Bell, Joseph; Woodward, Jonathan; ...

2016-10-22

Lithium containing chalcogenide single crystals have become very promising materials for photonics and radiation detection. Detection applications include nuclear nonproliferation, neutron science, and stellar investigations for the search of life. Synthesis and single crystal growth methods for lithium containing chalcogenide, specifically LiIn 1-xGa xSe 2, single crystals are discussed. This study elucidates the possibility of improving neutron detection by reducing the indium capture contribution; with the incorporation of the lithium-6 isotope, gallium substitution may overcome the neutron detection efficiency limitation of 6LiInSe 2 due to appreciable neutron capture by the indium-115 isotope. As a figure of merit, the ternary parentmore » compounds 6LiInSe 2 and 6LiGaSe 2 were included in this study. Quality crystals can be obtained utilizing the vertical Bridgman method to produce quaternary compounds with tunable optical properties. Here, quaternary crystals of varying quality depending on the gallium concentration, approximately 5 x 5 x 2 mm 3 or larger in volume, were harvested, analyzed and revealed tunable absorption characteristics between 2.8-3.4 eV.« less

Crystallization of Δ{sup 1}-tetrahydrocannabinolic acid (THCA) synthase from Cannabis sativa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shoyama, Yoshinari; Takeuchi, Ayako; Taura, Futoshi

Δ{sup 1}-Tetrahydrocannabinolic acid (THCA) synthase from C. sativa was crystallized. The crystal diffracted to 2.7 Å resolution with sufficient quality for further structure determination. Δ{sup 1}-Tetrahydrocannabinolic acid (THCA) synthase is a novel oxidoreductase that catalyzes the biosynthesis of the psychoactive compound THCA in Cannabis sativa (Mexican strain). In order to investigate the structure–function relationship of THCA synthase, this enzyme was overproduced in insect cells, purified and finally crystallized in 0.1 M HEPES buffer pH 7.5 containing 1.4 M sodium citrate. A single crystal suitable for X-ray diffraction measurement was obtained in 0.09 M HEPES buffer pH 7.5 containing 1.26 Mmore » sodium citrate. The crystal diffracted to 2.7 Å resolution at beamline BL41XU, SPring-8. The crystal belonged to the primitive cubic space group P432, with unit-cell parameters a = b = c = 178.2 Å. The calculated Matthews coefficient was approximately 4.1 or 2.0 Å{sup 3} Da{sup −1} assuming the presence of one or two molecules of THCA synthase in the asymmetric unit, respectively.« less

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape

PubMed Central

Zhang, Lin; Sánchez del Río, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I.; Glatzel, Pieter

2013-01-01

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results. PMID:23765298

Crystallization and preliminary X-ray crystallographic study of a 3.8-MDa respiratory supermolecule hemocyanin.

PubMed

Matsuno, Asuka; Gai, Zuoqi; Tanaka, Miyuki; Kato, Koji; Kato, Sanae; Katoh, Tsuyoshi; Shimizu, Takeshi; Yoshioka, Takeya; Kishimura, Hideki; Tanaka, Yoshikazu; Yao, Min

2015-06-01

Many molluscs transport oxygen using a very large cylindrical multimeric copper-containing protein named hemocyanin. The molluscan hemocyanin forms a decamer (cephalopods) or multidecamer (gastropods) of approximately 330-450kDa subunits, resulting in a molecular mass >3.3MDa. Therefore, molluscan hemocyanin is one of the largest proteins. The reason why these organisms use such a large supermolecule for oxygen transport remains unclear. Atomic-resolution X-ray crystallographic analysis is necessary to unveil the detailed molecular structure of this mysterious large molecule. However, its propensity to dissociate in solution has hampered the crystallization of its intact form. In the present study, we successfully obtained the first crystals of an intact decameric molluscan hemocyanin. The diffraction dataset at 3.0-Å resolution was collected by merging the datasets of two isomorphic crystals. Electron microscopy analysis of the dissolved crystals revealed cylindrical particles. Furthermore, self-rotation function analysis clearly showed the presence of a fivefold symmetry with several twofold symmetries perpendicular to the fivefold axis. The absorption spectrum of the crystals showed an absorption peak around 345nm. These results indicated that the crystals contain intact hemocyanin decamers in the oxygen-bound form. Copyright © 2015 Elsevier Inc. All rights reserved.

Growth, Crystal Structure and Magnetic Characterization of Zn-Stabilized CePtIn4

NASA Astrophysics Data System (ADS)

Carnicom, Elizabeth M.; Klimczuk, Tomasz; von Rohr, Fabian; Winiarski, Michal J.; Kong, Tai; Stolze, Karoline; Xie, Weiwei; Kushwaha, Satya K.; Cava, Robert J.

2017-08-01

The growth and characterization of CePtIn4, stabilized by 10% Zn substitution for In, is reported. The new material is orthorhombic, space group Cmcm (No. 63), with lattice parameters a = 4.51751(4) Å, b = 16.7570(2) Å, and c = 7.36682(8) Å, and the refined crystal composition has 10% of Zn substituted for In, i.e., the crystals are CePt(In0.9Zn0.1)4. Crystals were grown using a self-flux method: only growths containing Zn yielded CePtIn4 crystals, while Ce3Pt4In13 crystals formed when Zn was not present. Anisotropic temperature-dependent magnetic susceptibilities for single crystals show that Zn-stabilized CePtIn4 orders magnetically at ˜1.9 K. High-temperature Curie-Weiss fits indicate an effective moment of ˜2.49 μB/Ce and a directionally averaged Weiss-temperature of approximately -31 K. Specific heat data shows a peak consistent with the ordering temperature seen in the magnetic susceptibility data. Zn-stabilized CePtIn4 is metallic and displays no superconducting transition down to 0.14 K.

Weak ferromagnetism along the third-order axis of the FeBO3 crystals caused by Fe2+ impurity ions

NASA Astrophysics Data System (ADS)

Ovchinnikov, S. G.; Rudenko, V. V.; Vorotynov, A. M.

2018-05-01

Using the single-ion approximation, the weak ferromagnetic moment σZ(Fe2+) along the third-order axis of FeBO3 crystals, which is caused by the contribution of Fe2+ ions, has been investigated in the framework of the model Fe2+ impurity ion -BO3 vacancy. The extreme low-temperature behavior of the total magnetic moment due to the strong dependence of the Fe2+ion contribution is predicted.

Temporal intracavity detection of parasitic infrared absorption in Ti:Sapphire lasers

NASA Astrophysics Data System (ADS)

Deleva, A. D.; Peshev, Z. Y.; Aneva, Z. I.

1993-12-01

An intracavity technique with temporal sensitivity to optical losses is used to detect parasitic infrared absorption (PIRA) in Ti:sapphire crystals with high active-center concentrations. By means of comparative analysis, re-emission is established of part of the parasitically absorbed energy back into the laser action channel. A method is proposed for approximate quantitative determination of the relative part of re-emitting PIRA-centers with respect to their total number; for the highly-doped crystal described, it is estimated at about 11%.

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE PAGES

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; ...

2015-09-01

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Epitaxial Growth of Cubic Crystalline Semiconductor Alloys on Basal Plane of Trigonal or Hexagonal Crystal

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor)

2011-01-01

Hetero-epitaxial semiconductor materials comprising cubic crystalline semiconductor alloys grown on the basal plane of trigonal and hexagonal substrates, in which misfit dislocations are reduced by approximate lattice matching of the cubic crystal structure to underlying trigonal or hexagonal substrate structure, enabling the development of alloyed semiconductor layers of greater thickness, resulting in a new class of semiconductor materials and corresponding devices, including improved hetero-bipolar and high-electron mobility transistors, and high-mobility thermoelectric devices.

Crystal and molecular structures of 3-amino-4-hydroxy benzenesulfonamide and its hydrochloride: Quantum-chemical study of their tautomerism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovalchukova, O. V., E-mail: okovalchukova@mail.ru; Strashnova, S. B.; Romashkina, E. P.

2013-03-15

3-amino-4-hydroxy benzenesulfonamide and its hydrochloride have been isolated in the crystalline state. Their crystal and molecular structures are determined by X-ray diffraction. The equilibrium between neutral tautomeric forms of the 3-amino-4-hydroxy benzenesulfonamide molecule is studied within the approximation of density functional theory (B3LYP/aug-cc-pVDZ). The constants of acid-base equilibrium of 3-amino-4-hydroxy benzenesulfonamide are deter-mined using spectrophotometry.

Crystallization of Δ1-tetrahydrocannabinolic acid (THCA) synthase from Cannabis sativa

PubMed Central

Shoyama, Yoshinari; Takeuchi, Ayako; Taura, Futoshi; Tamada, Taro; Adachi, Motoyasu; Kuroki, Ryota; Shoyama, Yukihiro; Morimoto, Satoshi

2005-01-01

Δ1-Tetrahydrocannabinolic acid (THCA) synthase is a novel oxidoreductase that catalyzes the biosynthesis of the psychoactive compound THCA in Cannabis sativa (Mexican strain). In order to investigate the structure–function relationship of THCA synthase, this enzyme was overproduced in insect cells, purified and finally crystallized in 0.1 M HEPES buffer pH 7.5 containing 1.4 M sodium citrate. A single crystal suitable for X-ray diffraction measurement was obtained in 0.09 M HEPES buffer pH 7.5 containing 1.26 M sodium citrate. The crystal diffracted to 2.7 Å resolution at beamline BL41XU, SPring-8. The crystal belonged to the primitive cubic space group P432, with unit-cell parameters a = b = c = 178.2 Å. The calculated Matthews coefficient was approximately 4.1 or 2.0 Å3 Da−1 assuming the presence of one or two molecules of THCA synthase in the asymmetric unit, respectively. PMID:16511162

Cirrus properties deduced from CO2 lidar observations of zenith-enhanced backscatter from oriented crystals

NASA Technical Reports Server (NTRS)

Eberhard, Wynn L.

1993-01-01

Many lidar researchers have occasionally observed zenith-enhanced backscatter (ZEB) from middle and high clouds. The ZEB signature consists of strong backscatter when the lidar is pointed directly at zenith and a dramatic decline in backscatter as the zenith angle dips slightly off zenith. Mirror-like reflection from horizontal facets of oriented crystals (especially plates) is generally accepted as the cause. It was found during a 3-year observation program that approximately 50 percent of ice clouds had ZEB, regardless of cloud height. The orientation of crystals and the ZEB they cause are important to study and understand for several reasons. First, radiative transfer in clouds with oriented crystals is different than if the same particles were randomly oriented. Second, crystal growth depends partly on the orientation of the particles. Third, ZEB measurements may provide useful information about cirrus microphysical and radiative properties. Finally, the remarkable effect of ZEB on lidar signals should be understood in order to properly interpret lidar data.

A monoclinic, pseudo-orthorhombic Au-Hg mineral of potential economic significance in Pleistocene Snake River alluvial deposits of southeastern Idaho

USGS Publications Warehouse

Desborough, G.A.; Foord, E.E.

1992-01-01

A mineral with the approximate composition of Au94Hg6 - Au88Hg12 (atomic %) has been identified in Pleistocene Snake River alluvial deposits. The gold-mercury mineral occurs as very small grains or as polycrystalline masses composed of subhedral to nearly euhedral attached crystals. Vibratory cold-polishing techniques with 0.05-??m alumina abrasive for polished sections revealed a porous internal texture for most subhedral crystals after 48-72 hours of treatment. Thus, optical character (isotropic or anisotropic) could not be determined by reflected-light microscopy, and pore-free areas were too small for measurement of reflectance. X-ray-diffraction lines rather than individual reflections (spots), on powder camera X-ray films of unrotated spindles of single grains that morphologically appear to be single crystals, indicate that individual subhedral or euhedral crystals are composed of domains in random orientation. Thus, no material was found suitable for single-crystal X-ray diffraction studies. -from Authors

Thermal and convection analyses of the dendrite remelting rocket experiment; Experiment 74-21 in the space processing rocket program

NASA Technical Reports Server (NTRS)

Grodzka, P. G.; Pond, J. E.; Spradley, J. W.; Johnson, M. H.

1976-01-01

The Dendrite Remelting Rocket Experiment was performed aboard a Black Brant VC Sounding Rocket during a period which gravity levels of approximately 0.00001 g prevailed. The experiment consisted of cooling an aqueous ammonium chloride solution in a manner such that crystallization of ammonium chloride crystals proceeded throughout a three minute period of zero-g. The crystallization process during flight was recorded on 35 mm panatomic-x film. A number of ground crystallizations were similarly recorded for comparison purposes. The convective and thermal conditions in aqueous and metallic liquid systems were assessed under conditions of the flight experiment to help establish the relevance of the rocket experiment to metals casting phenomena. The results indicate that aqueous or metallic convective velocities in the Dendrite Remelting Rocket Experiment cell are of insignificant magnitudes at the 0.0001 to 0.00001 g levels of the experiment. The crystallization phenomena observed in the Rocket Experiment, therefore, may be indicative of how metals will solidify in low-g.

Design and fabrication of PZN-7%PT single crystal high frequency angled needle ultrasound transducers.

PubMed

Zhou, Qifa; Wu, Dawei; Jin, Jing; Hu, Chang-hong; Xu, Xiaochen; Williams, Jay; Cannata, Jonathan M; Lim, Leongchew; Shung, K Kirk

2008-01-01

A high-frequency angled needle ultrasound transducer with an aperture size of 0.4 x 0.56 mm2 was fabricated using a lead zinc niobate-lead titanate (PZN- 7%PT) single crystal as the active piezoelectric material. The single crystal was bonded to a conductive silver particle matching layer and a conductive epoxy backing material through direct contact curing. A parylene outer matching layer was formed by vapor deposition. Angled needle probe configuration was achieved by dicing at 45 degrees to the single crystal poling direction to satisfy a clinical request for blood flow measurement in the posterior portion of the eye. The electrical impedance magnitude and phase of the transducer were 42 Omega and -63 degrees , respectively. The measured center frequency and the fractional bandwidth at -6 dB were 43 MHz and 45%, respectively. The two-way insertion loss was approximately 17 dB. Wire phantom imaging using fabricated PZN-7%PT single crystal transducers was obtained and spatial resolutions were assessed.

Zn3Sb4O6F6: Hydrothermal synthesis, crystal structure and nonlinear optical properties

NASA Astrophysics Data System (ADS)

Ali, Sk Imran; Zhang, Weiguo; Halasyamani, P. Shiv; Johnsson, Mats

2017-12-01

Zn3Sb4O6F6 has been synthesized hydrothermally at 230 °C. The crystal structure was determined from single crystal X-ray diffraction data. It crystallizes in the cubic non-centrosymmetric space group I-43m with the unit cell parameter a = 8.1291(4) Å and is isostructural with M3Sb4O6F6 (M = Co, Ni). The new compound is the first oxofluoride containing Zn2+ and a p-element cation with a stereochemically active lone pair. The crystal structure is made up by [ZnO2F4] octahedra forming a network via corner sharing at F-atoms and [SbO3] trigonal pyramids that form [Sb4O6] cages that connect via the O-atoms to the Zn-atoms. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation on Zn3Sb4O6F6 indicate an SHG intensity of approximately 40 × α-SiO2.

The growth of deactivated layers on CsI(Na) scintillating crystals

NASA Technical Reports Server (NTRS)

Goodman, N. B.

1975-01-01

An effective and sensitive measurement of the depth of a deactivated or dead layer can be obtained from the relative attenuation of the 22.162 KeV and 87.9 KeV X-rays emitted by Cd 109. The alpha-particles emitted by Am 241 are also useful in measuring dead layers less than 25 microns. The properties and temporal development of dead layers are discussed in detail. The rate of growth of a deal layer is closely related to the ambient humidity, and the damage to the crystal is irreversible by any known process. The dead layer can be minimized by polishing all crystal surfaces and by keeping the crystal in a vacuum or a dry atmosphere. Since a dead layer seriously inhibits the response of a crystal to X-rays of energies below approximately 20 keV, CsI(Na) detectors should not be used at these energies unless precautions are taken to ensure that no dead layer forms.

Mechanical and structural model of fractal networks of fat crystals at low deformations.

PubMed

Narine, S S; Marangoni, A G

1999-12-01

Fat-crystal networks demonstrate viscoelastic behavior at very small deformations. A structural model of these networks is described and supported by polarized light and atomic-force microscopy. A mechanical model is described which allows the shear elastic modulus (G') of the system to be correlated with forces acting within the network. The fractal arrangement of the network at certain length scales is taken into consideration. It is assumed that the forces acting are due to van der Waals forces. The final expression for G' is related to the volume fraction of solid fat (Phi) via the mass fractal dimension (D) of the network, which agrees with the experimental verification of the scaling behavior of fat-crystal networks [S. S. Narine and A. G. Marangoni, Phys. Rev. E 59, 1908 (1999)]. G' was also found to be inversely proportional to the diameter of the primary particles (sigma approximately equal to 6 microm) within the network (microstructural elements) as well as to the diameter of the microstructures (xi approximately equal to 100 microm) and inversely proportional to the cube of the intermicrostructural element distance (d(0)). This formulation of the elastic modulus agrees well with experimental observations.

Estimating the Aqueous Solubility of Pharmaceutical Hydrates.

PubMed

Franklin, Stephen J; Younis, Usir S; Myrdal, Paul B

2016-06-01

Estimation of crystalline solute solubility is well documented throughout the literature. However, the anhydrous crystal form is typically considered with these models, which is not always the most stable crystal form in water. In this study, an equation which predicts the aqueous solubility of a hydrate is presented. This research attempts to extend the utility of the ideal solubility equation by incorporating desolvation energetics of the hydrated crystal. Similar to the ideal solubility equation, which accounts for the energetics of melting, this model approximates the energy of dehydration to the entropy of vaporization for water. Aqueous solubilities, dehydration and melting temperatures, and log P values were collected experimentally and from the literature. The data set includes different hydrate types and a range of log P values. Three models are evaluated, the most accurate model approximates the entropy of dehydration (ΔSd) by the entropy of vaporization (ΔSvap) for water, and utilizes onset dehydration and melting temperatures in combination with log P. With this model, the average absolute error for the prediction of solubility of 14 compounds was 0.32 log units. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Analysis of pulsed-neutron powder diffraction patterns of the icosahedral quasicrystals Pd3Siu and AlCuLiMg (three alloys) as twinned cubic crystals with large units.

PubMed Central

Pauling, L

1991-01-01

The low-Q peaks on three pulsed-neutron powder patterns (total, U differential, and Pd differential) of the icosahedral quasicrystal Pd3SiU have been indexed on the basis of an assumed cubic structure of the crystals that by icosahedral twinning form the quasicrystal. The primitive unit cube is found to have edge length 56.20 A and to contain approximately 12,100 atoms. Similar analyses of pulsed-neutron patterns of Al55Cu10Li35, Al55Cu10Li30Mg5, and Al510Cu125Li235Mg130 give values of the cube edge length 58.3, 58.5, and 58.4 A, respectively, with approximately 11,650 atoms in the unit cube. It is suggested that the unit contains eight complexes in the beta-W positions, plus some small interstitial groups of atoms, with each complex consisting of a centered icosahedron of 13 clusters, each of 116 atoms with the icosahedral structure found in the body-centered cubic crystal Mg32(Al,Zn)49. PMID:11607201

Analysis of pulsed-neutron powder diffraction patterns of the icosahedral quasicrystals Pd3Siu and AlCuLiMg (three alloys) as twinned cubic crystals with large units.

PubMed

Pauling, L

1991-08-01

The low-Q peaks on three pulsed-neutron powder patterns (total, U differential, and Pd differential) of the icosahedral quasicrystal Pd3SiU have been indexed on the basis of an assumed cubic structure of the crystals that by icosahedral twinning form the quasicrystal. The primitive unit cube is found to have edge length 56.20 A and to contain approximately 12,100 atoms. Similar analyses of pulsed-neutron patterns of Al55Cu10Li35, Al55Cu10Li30Mg5, and Al510Cu125Li235Mg130 give values of the cube edge length 58.3, 58.5, and 58.4 A, respectively, with approximately 11,650 atoms in the unit cube. It is suggested that the unit contains eight complexes in the beta-W positions, plus some small interstitial groups of atoms, with each complex consisting of a centered icosahedron of 13 clusters, each of 116 atoms with the icosahedral structure found in the body-centered cubic crystal Mg32(Al,Zn)49.

Effect of citric acid on setting reaction and tissue response to β-TCP granular cement.

PubMed

Fukuda, Naoyuki; Tsuru, Kanji; Mori, Yoshihide; Ishikawa, Kunio

2017-02-24

We recently reported that when an acidic calcium phosphate solution is mixed with β-tricalcium phosphate (β-TCP) granules, the resulting dicalcium phosphate dihydrate (DCPD) crystals form bridges between the β-TCP granules, creating a set interconnected porous structure in approximately 1 min. Although this self-setting β-TCP granular cement (β-TCPGC) is useful for clinical applications, the short setting time is a key drawback for handling. In this study, the setting time of β-TCPGC was adjusted with the addition of citric acid, which is a known inhibiter of DCPD crystal growth. As the concentration of citric acid in the acidic calcium phosphate solution increased, the amount of DCPD formation in the set β-TCPGC decreased, and the crystal morphology of DCPD became elongated. β-TCPGC prepared with various citric acid concentrations were used as grafting material in rat calvarial bone defects to evaluate bone regeneration in vivo. Four weeks after implantation, no inflammatory reaction and approximately 20% new bone formation were observed, regardless of the presence or absence of citric acid in the liquid phase of β-TCPGC. We concluded, therefore, that citric acid might be a useful retarder of β-TCPGC setting times.

Electronic structure of Ag7GeS5I superionic compound

NASA Astrophysics Data System (ADS)

Bletskan, Dmytro; Studenyak, Ihor; Bletskan, Mykhailo; Vakulchak, Vasyl

2018-05-01

This paper presents the originally results of ab initio calculations of electronic structure, total and partial densities of electronic states as well as electronic charge density distribution of Ag7GeS5I crystal performed within the density functional theory (DFT) in the local density approximation (LDA) for exchange-correlation potential. According to performed calculations, Ag7GeS5I is the direct-gap semiconductor with the valence band top and the conductivity band bottom in the Γ point of Brillouin zone. The band gap width calculated in the LDA-approximation is Egd = 0.73 eV. The analysis of total and partial densities of electronic states allow us to identify the atomic orbital contributions into the crystal orbitals as well as the formation data of chemical bond in the studied crystal. In the top part of Ag7GeS5I valence band it was revealed the considerable mixing (hybridization) of the occupied d-states of Ag noble metal and the delocalized p-states of sulfur and iodine, which is undoubtedly associated with the covalent character of chemical bond between S, I atoms and noble metal atom.

Thermally-prepared polymorphic forms of cilostazol.

PubMed

Stowell, Grayson W; Behme, Robert J; Denton, Stacy M; Pfeiffer, Inigo; Sancilio, Frederick D; Whittall, Linda B; Whittle, Robert R

2002-12-01

Prior to this study, cilostazol, an antithrombotic drug, was thought to exist as a single crystalline phase with a melting point of approximately 159 degrees C (Form A). On cooling, melts often form a glass that, when heated, may crystallize as additional crystalline polymorphic forms. Cilostazol, when reheated, subsequently forms polymorphs that melt at approximately 136 degrees C (Form B) and 146 degrees C (Form C). Free-energy temperature diagrams estimated from calorimetry data reveal that each pair of the cilostazol polymorphs (A-B, B-C, and A-C) is monotropic. Essentially pure samples of suitable crystalline shape and size permitted single crystal structural analysis of Forms A and C. Theoretical solubility ratios calculated using calorimetry data indicate that at 37 degrees C, Form B should be more than four times more soluble and Form C should be more than two times more soluble than Form A. Forms B and C could not be crystallized from solvents. Metastable forms from super cooled melts analyzed by intrinsic dissolution and Fourier transform-Raman experiments demonstrated that Forms B and C undergo a rapid, solvent-mediated recrystallization to Form A, making dissolution rate measurements difficult. Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:2481-2488, 2002

Why don't we find more polymorphs?

PubMed

Price, Sarah L

2013-08-01

Crystal structure prediction (CSP) studies are not limited to being a search for the most thermodynamically stable crystal structure, but play a valuable role in understanding polymorphism, as shown by interdisciplinary studies where the crystal energy landscape has been explored experimentally and computationally. CSP usually produces more thermodynamically plausible crystal structures than known polymorphs. This article illustrates some reasons why: because (i) of approximations in the calculations, particularly the neglect of thermal effects (see §1.1); (ii) of the molecular rearrangement during nucleation and growth (see §1.2); (iii) the solid-state structures observed show dynamic or static disorder, stacking faults, other defects or are not crystalline and so represent more than one calculated structure (see §1.3); (iv) the structures are metastable relative to other molecular compositions (see §1.4); (v) the right crystallization experiment has not yet been performed (see §1.5) or (vi) cannot be performed (see §1.6) and the possibility (vii) that the polymorphs are not detected or structurally characterized (see §1.7). Thus, we can only aspire to a general predictive theory for polymorphism, as this appears to require a quantitative understanding of the kinetic factors involved in all possible multi-component crystallizations. For a specific molecule, analysis of the crystal energy landscape shows the potential complexity of its crystallization behaviour.

Compaction by impact of unconsolidated lunar fines

NASA Technical Reports Server (NTRS)

Ahrens, T. J.

1975-01-01

New Hugoniot and release adiabat data for 1.8 g/cu cm lunar fines in the approximately 2 to 70 kbar range demonstrate that upon shock compression intrinsic crystal density (approximately 3.1 g/cu cm) is achieved under shock stress of 15 to 20 kbar. Release adiabat determinations indicate that measurable irreversible compaction occurs upon achieving shock pressures above approximately 4 kbar. For shocks in the approximately 7 to 15 kbar range, the inferred post-shock specific volumes observed decrease nearly linearly with increasing peak shock pressures. Upon shocking to approximately 15 kbar the post-shock density is approximately that of the intrinsic minerals. If the present data are taken to be representative of the response to impact of unconsolidated regolith material on the moon, it is inferred that the formation of appreciable quantities of soil breccia can be associated with the impact of meteoroids or ejecta at speeds as low as approximately 1 km/sec.

Early Petrogenesis and Late Impact(?) Metamorphism on the GRA 06128/9 Parent Body

NASA Technical Reports Server (NTRS)

Nyquist, Laurence E.; Shih, C.-Y.; Reese, Y. D.

2009-01-01

Initial studies of GRA06128 and GRA06129 (hereafter GRA 8 and GRA 9) suggested that these alkalic meteorites represent partial melts of a parent body of approximately chondritic composition. A SM-147-Nd-143 isochron age of 4.545 +/- 0.087 Ga was found for GRA 8, but plagioclase (oligoclase) plus whole rock and leachate samples gave an apparent secondary age of approximately 3.5 Ga. The approximately 4.54 Ga age was interpreted to be the crystallization age of GRA 8; the approximately 3.5 Ga as an upper limit to a time of metamorphism. Here we extend Sm-Nd and Rb-Sr analyses to GRA 9.

Prism-coupled Cherenkov phase-matched terahertz wave generation using a DAST crystal.

PubMed

Suizu, Koji; Shibuya, Takayuki; Uchida, Hirohisa; Kawase, Kodo

2010-02-15

Terahertz (THz) wave generation based on nonlinear frequency conversion is a promising method for realizing a tunable monochromatic high-power THz-wave source. Unfortunately, many nonlinear crystals have strong absorption in the THz frequency region. This limits efficient and widely tunable THz-wave generation. The Cherenkov phase-matching method is one of the most promising techniques for overcoming these problems. Here, we propose a prism-coupled Cherenkov phase-matching (PCC-PM) method, in which a prism with a suitable refractive index at THz frequencies is coupled to a nonlinear crystal. This has the following advantages. Many crystals can be used as THz-wave emitters; the phase-matching condition inside the crystal does not have to be observed; the absorption of the crystal does not prevent efficient generation of radiation; and pump sources with arbitrary wavelengths can be employed. Here we demonstrate PCC-PM THz-wave generation using the organic crystal 4-dimethylamino-N-metyl-4-stilbazolium tosylate (DAST) and a Si prism coupler. We obtain THz-wave radiation with tunability of approximately 0.1 to 10 THz and with no deep absorption features resulting from the absorption spectrum of the crystal. The obtained spectra did not depend on the pump wavelength in the range 1300 to 1450 nm. This simple technique shows promise for generating THz radiation using a wide variety of nonlinear crystals.

A Linear Relationship between Crystal Size and Fragment Binding Time Observed Crystallographically: Implications for Fragment Library Screening Using Acoustic Droplet Ejection

PubMed Central

Birone, Claire; Brown, Maria; Hernandez, Jesus; Neff, Sherry; Williams, Daniel; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

2014-01-01

High throughput screening technologies such as acoustic droplet ejection (ADE) greatly increase the rate at which X-ray diffraction data can be acquired from crystals. One promising high throughput screening application of ADE is to rapidly combine protein crystals with fragment libraries. In this approach, each fragment soaks into a protein crystal either directly on data collection media or on a moving conveyor belt which then delivers the crystals to the X-ray beam. By simultaneously handling multiple crystals combined with fragment specimens, these techniques relax the automounter duty-cycle bottleneck that currently prevents optimal exploitation of third generation synchrotrons. Two factors limit the speed and scope of projects that are suitable for fragment screening using techniques such as ADE. Firstly, in applications where the high throughput screening apparatus is located inside the X-ray station (such as the conveyor belt system described above), the speed of data acquisition is limited by the time required for each fragment to soak into its protein crystal. Secondly, in applications where crystals are combined with fragments directly on data acquisition media (including both of the ADE methods described above), the maximum time that fragments have to soak into crystals is limited by evaporative dehydration of the protein crystals during the fragment soak. Here we demonstrate that both of these problems can be minimized by using small crystals, because the soak time required for a fragment hit to attain high occupancy depends approximately linearly on crystal size. PMID:24988328

A linear relationship between crystal size and fragment binding time observed crystallographically: implications for fragment library screening using acoustic droplet ejection.

PubMed

Cole, Krystal; Roessler, Christian G; Mulé, Elizabeth A; Benson-Xu, Emma J; Mullen, Jeffrey D; Le, Benjamin A; Tieman, Alanna M; Birone, Claire; Brown, Maria; Hernandez, Jesus; Neff, Sherry; Williams, Daniel; Allaire, Marc; Orville, Allen M; Sweet, Robert M; Soares, Alexei S

2014-01-01

High throughput screening technologies such as acoustic droplet ejection (ADE) greatly increase the rate at which X-ray diffraction data can be acquired from crystals. One promising high throughput screening application of ADE is to rapidly combine protein crystals with fragment libraries. In this approach, each fragment soaks into a protein crystal either directly on data collection media or on a moving conveyor belt which then delivers the crystals to the X-ray beam. By simultaneously handling multiple crystals combined with fragment specimens, these techniques relax the automounter duty-cycle bottleneck that currently prevents optimal exploitation of third generation synchrotrons. Two factors limit the speed and scope of projects that are suitable for fragment screening using techniques such as ADE. Firstly, in applications where the high throughput screening apparatus is located inside the X-ray station (such as the conveyor belt system described above), the speed of data acquisition is limited by the time required for each fragment to soak into its protein crystal. Secondly, in applications where crystals are combined with fragments directly on data acquisition media (including both of the ADE methods described above), the maximum time that fragments have to soak into crystals is limited by evaporative dehydration of the protein crystals during the fragment soak. Here we demonstrate that both of these problems can be minimized by using small crystals, because the soak time required for a fragment hit to attain high occupancy depends approximately linearly on crystal size.

Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

PubMed Central

2015-01-01

Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6̅m2 (crystal class 6̅m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

Self-consistent-field KKR-CPA calculations in the atomic-sphere approximations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, P.P. Gonis, A.; de Fontaine, D.

1991-12-03

We present a formulation of the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) for the treatment of substitutionally disordered alloys within the KKR atomic-sphere approximations (ASA). This KKR-ASA-CPA represents the first step toward the implementation of a full cell potential CPA, and combines the accuracy of the KKR-CPA method with the flexibility of treating complex crystal structures. The accuracy of this approach has been tested by comparing the self-consistent-field (SCF) KKR-ASA-CPA calculations of Cu-Pd alloys with experimental results and previous SCF-KKR-CPA calculations.

77 FR 64561 - President's Committee on the Arts and the Humanities: Meeting #68

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-22

... Committee on the Arts and the Humanities (PCAH) will be held in the Crystal Room, The Willard Intercontinental, 1401 Pennsylvania Avenue NW, Washington, DC 20004. Ending time is approximate. DATES: November 18...

78 FR 67203 - President's Committee on the Arts and the Humanities: Meeting #69

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-08

... Committee on the Arts and the Humanities (PCAH) will be held in the Crystal Room, The Willard Intercontinental, 1401 Pennsylvania Avenue NW., Washington, DC 20004. Ending time is approximate. DATES: November...

Radioluminescence and photoluminescence properties of Dy-doped 12CaO • 7Al2O3 single crystals synthesized by the floating zone method

NASA Astrophysics Data System (ADS)

Kumamoto, Narumi; Nakauchi, Daisuke; Kato, Takumi; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-02-01

We have synthesized Dy-doped 12CaO • 7Al2O3 (Dy:C12A7) single crystals with various Dy concentrations by the floating zone (FZ) method and investigated the photoluminescence (PL) and X-ray induced radioluminescence (RL) properties. The PL emissions are observed around 480-490, 570-590, 650-690, and 750 nm due to the 4f-4f transitions of Dy3+ under excitation around 350-400 and 450 nm. The decay time constant (580 nm emission under 340-390 nm excitation) was approximately 0.54-0.58 ms. The RL also showed line emissions at 487, 580, 668, and 757 nm due to the 4f-4f transitions of Dy3+ while the decay time was approximately 0.49-0.53 ms.

Absorption and quasiguided mode analysis of organic solar cells with photonic crystal photoactive layers.

PubMed

Tumbleston, John R; Ko, Doo-Hyun; Samulski, Edward T; Lopez, Rene

2009-04-27

We analyze optical absorption enhancements and quasiguided mode properties of organic solar cells with highly ordered nanostructured photoactive layers comprised of the bulk heterojunction blend, poly-3-hexylthiophene/[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) and a low index of refraction conducting material (LICM). This photonic crystal geometry is capable of enhancing spectral absorption by approximately 17% in part due to the excitation of quasiguided modes near the band edge of P3HT:PCBM. A nanostructure thickness between 200 nm and 300 nm is determined to be optimal, while the LICM must have an index of refraction approximately 0.3 lower than P3HT:PCBM to produce absorption enhancements. Quasiguided modes that differ in lifetime by an order of magnitude are also identified and yield absorption that is concentrated in the P3HT:PCBM flash layer.

Diagenetic Crystal Clusters and Dendrites, Lower Mount Sharp, Gale Crater

NASA Technical Reports Server (NTRS)

Kah, L. C.; Kronyak, R.; Van Beek, J.; Nachon, M.; Mangold, N.; Thompson, L.; Wiens, R.; Grotzinger, J.; Farmer, J.; Minitti, M.;

Gompertz type dechanneling functions for protons in <1 0 0>, <1 1 0> and <1 1 1> Si crystal channels

NASA Astrophysics Data System (ADS)

Petrović, S.; Erić, M.; Kokkoris, M.; Nešković, N.

2007-03-01

In this work the energy dependences of the Gompertz type sigmoidal dechanneling function parameters for protons in <1 0 0>, <1 1 0> and <1 1 1> Si crystal channels is investigated theoretically. The proton energy range considered is between 1 and 10 MeV. The original dechanneling functions are generated using a realistic Monte Carlo computer simulation code. We show that the Gompertz type dechanneling function, having two parameters, lc and k, representing the dechanneling range and rate, respectively, approximate accurately the original dechanneling function. It is also shown that the energy dependences of parameters lc and k can be approximated by a linear function and a sum of two exponential functions, respectively. The results obtained can be used for accurate reproduction of experimental proton channeling spectra recorded in the backscattering geometry.

Solid-state modeling of the terahertz spectrum of the high explosive HMX.

PubMed

Allis, Damian G; Prokhorova, Darya A; Korter, Timothy M

2006-02-09

The experimental solid-state terahertz (THz) spectrum (3-120 cm(-1)) of the beta-crystal form of the high explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) has been analyzed using solid-state density functional theory calculations. Various density functionals (both generalized gradient approximation and local density approximation) are compared in terms of their abilities to reproduce the experimentally observed solid-state structure and low-frequency vibrational motions. Good-to-excellent agreement between solid-state theory and experiment can be achieved in the THz region where isolated-molecule calculations fail to reproduce the observed spectral features, demonstrating a clear limitation of using isolated-molecule calculations for the assignment of THz frequency motions in molecular solids. The deficiency of isolated-molecule calculations is traced to modification of the molecular structure in the solid state through crystal packing effects and the formation of weak C-H...O hydrogen bonds.

Ureilite smelting

NASA Technical Reports Server (NTRS)

Walker, David; Grove, Tim

1993-01-01

Ureilites containing homogeneous Fo76 olivine cores in intimate co-existence with graphite must have recrystallized at pressures of at least approximately 100 bars to suppress smelting of the fayalite component of the olivine to Fe metal. Smelting of olivine and pyroxene-saturated magmatic liquids produces orthopyroxene-without-olivine crystalline derivatives unlike those in ureilites. Thus the Mg# compositional variation within the ureilite suite, which is commonly attributed to partial smelting, cannot plausibly be produced by assemblages rich in liquid. In situ smelting of graphitic olivine + pigeonite crystal mushes can produce the correct crystal assemblage, but fails to provide a plausible account for the removal of metal from ureilites or for the correlation of Mg# with Delta O-17. Even if Mg# and Delta O-17 variations are established in the nebula, ureilite recrystallization with graphite must have occurred at pressures greater than the minima we have experimentally established, corresponding to parent objects not less than approximately 100 km in radius.

Comparison of approximations in density functional theory calculations: Energetics and structure of binary oxides

NASA Astrophysics Data System (ADS)

Hinuma, Yoyo; Hayashi, Hiroyuki; Kumagai, Yu; Tanaka, Isao; Oba, Fumiyasu

2017-09-01

High-throughput first-principles calculations based on density functional theory (DFT) are a powerful tool in data-oriented materials research. The choice of approximation to the exchange-correlation functional is crucial as it strongly affects the accuracy of DFT calculations. This study compares performance of seven approximations, six of which are based on Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) with and without Hubbard U and van der Waals corrections (PBE, PBE+U, PBED3, PBED3+U, PBEsol, and PBEsol+U), and the strongly constrained and appropriately normed (SCAN) meta-GGA on the energetics and crystal structure of elementary substances and binary oxides. For the latter, only those with closed-shell electronic structures are considered, examples of which include C u2O , A g2O , MgO, ZnO, CdO, SnO, PbO, A l2O3 , G a2O3 , I n2O3 , L a2O3 , B i2O3 , Si O2 , Sn O2 , Pb O2 , Ti O2 , Zr O2 , Hf O2 , V2O5 , N b2O5 , T a2O5 , Mo O3 , and W O3 . Prototype crystal structures are selected from the Inorganic Crystal Structure Database (ICSD) and cation substitution is used to make a set of existing and hypothetical oxides. Two indices are proposed to quantify the extent of lattice and internal coordinate relaxation during a calculation. The former is based on the second invariant and determinant of the transformation matrix of basis vectors from before relaxation to after relaxation, and the latter is derived from shifts of internal coordinates of atoms in the unit cell. PBED3, PBEsol, and SCAN reproduce experimental lattice parameters of elementary substances and oxides well with few outliers. Notably, PBEsol and SCAN predict the lattice parameters of low dimensional structures comparably well with PBED3, even though these two functionals do not explicitly treat van der Waals interactions. SCAN gives formation enthalpies and Gibbs free energies closest to experimental data, with mean errors (MEs) of 0.01 and -0.04 eV, respectively, and root-mean-square errors (RMSEs) are both 0.07 eV. In contrast, all GGAs including those with Hubbard U and van der Waals corrections give 0.1 to 0.2 eV MEs and at least 0.11 eV RMSEs. Phonon contributions of solid phases to the formation enthalpies and Gibbs free energies are estimated to be small at less than ˜0.1 eV/atom within the quasiharmonic approximation. The same crystal structure appears as the lowest energy polymorph with different approximations in most of the investigated binary oxides. However, there are some systems where the choice of approximation significantly affects energy differences between polymorphs, or even the order of stability between phases. SCAN is the most reasonable regarding relative energies between polymorphs. The calculated transition pressure between polymorphs of ZnO and Sn O2 is closest to experimental values when PBED3, PBEsol (also PBED3+U and PBEsol+U for ZnO), and SCAN are employed. In summary, SCAN appears to be the best choice among the seven approximations based on the analysis of the energetics and crystal structure of binary oxides, while PBEsol is the best among the GGAs considered and shows a comparably good performance with SCAN for many cases. The use of PBEsol+U alongside PBEsol is also a reasonable choice, given that U corrections are required for several materials to qualitatively reproduce their electronic structures.

Properties of magnetized Coulomb crystals of ions with polarizable electron background

NASA Astrophysics Data System (ADS)

Kozhberov, A. A.

2018-06-01

We have studied phonon and thermodynamic properties of a body-centered cubic (bcc) Coulomb crystal of ions with weakly polarized electron background in a uniform magnetic field B. At B = 0, the difference between phonon moments calculated using the Thomas-Fermi (TF) and random phase approximations is always less than 1% and for description of phonon properties of a crystal, TF formalism was used. This formalism was successfully applied to investigate thermodynamic properties of magnetized Coulomb crystals. It was shown that the influence of the polarization of the electron background is significant only at κ TF a > 0.1 and T ≪ T p ( 1 + h2 ) - 1 / 2 , where κTF is the Thomas-Fermi wavenumber, a is the ion sphere radius, T p ≡ ℏ ω p is the ion plasma temperature, h ≡ ω B / ω p , ωB is the ion cyclotron frequency, and ωp is the ion plasma frequency.

Crystal structure of spinach plastocyanin at 1.7 A resolution.

PubMed Central

Xue, Y.; Okvist, M.; Hansson, O.; Young, S.

1998-01-01

The crystal structure of plastocyanin from spinach has been determined using molecular replacement, with the structure of plastocyanin from poplar as a search model. Successful crystallization was facilitated by site-directed mutagenesis in which residue Gly8 was substituted with Asp. The region around residue 8 was believed to be too mobile for the wild-type protein to form crystals despite extensive screening. The current structure represents the oxidized plastocyanin, copper (II), at low pH (approximately 4.4). In contrast to the similarity in the core region as compared to its poplar counterpart, the structure shows some significant differences in loop regions. The most notable is the large shift of the 59-61 loop where the largest shift is 3.0 A for the C(alpha) atom of Glu59. This results in different patterns of electrostatic potential around the acidic patches for the two proteins. PMID:9792096

Apparatus for single ice crystal growth from the melt.

PubMed

Zepeda, Salvador; Nakatsubo, Shunichi; Furukawa, Yoshinori

2009-11-01

A crystal growth apparatus was designed and built to study the effect of growth modifiers, antifreeze proteins and antifreeze glycoproteins (AFGPs), on ice crystal growth kinetics and morphology. We used a capillary growth technique to obtain a single ice crystal with well-defined crystallographic orientation grown in AFGP solution. The basal plane was readily observed by rotation of the capillary. The main growth chamber is approximately a 0.8 ml cylindrical volume. A triple window arrangement was used to minimize temperature gradients and allow for up to 10 mm working distance objective lens. Temperature could be established to within +/-10 mK in as little as 3.5 min and controlled to within +/-2 mK after 15 min for at least 10 h. The small volume growth chamber and fast equilibration times were necessary for parabolic flight microgravity experiments. The apparatus was designed for use with inverted and side mount configurations.

Studies of Islands on Freely Suspended Bubbles of Smectic Liquid Crystal

NASA Technical Reports Server (NTRS)

Pattanaporkratana, A.; Mavel, B.; Park, C. S.; Maclennan, J. E.; Clark, N. A.

2002-01-01

We have constructed an optical system for observing the internal structure of freely suspended smectic liquid crystal bubbles using a reflected light microscope. Liquid crystal bubbles can have thicker circular regions (islands) which can easily be generated by shrinking the bubble diameter. The diameter of these islands is approximately 10 microns and they are typically up to five times thicker than the surrounding liquid crystal film (500 angstroms). In the Laboratory, the location of the islands is strongly influenced by gravity, which causes the majority of islands to migrate to the bottom half of the bubble. We will describe the size and thickness distributions of islands and their time evolution, and also discuss two-dimensional hydrodynamics and turbulence of smectic bubbles, the shapes of islands and holes affected by bubble vibrations, and the interactions between islands, which we have probed using optical tweezers.

Planetoid core crystallisation and fractionation - Evidence from the Agpalilik mass of the Cape York iron meteorite shower

NASA Astrophysics Data System (ADS)

Esbensen, K. H.; Buchwald, V. F.

1982-09-01

Metallographic and chemical study of the Agpalik mass of the Cape York iron meteorite shower reveals evidence of the mode of crystallization and fractionation of key elements consistent with a dendritic solidification of at least part of the once fully molten parent body's metallic core. Chemical gradients of Ir and Au are assessed across an 85 cm section that is inferred to be perpendicular to the parent body's gravitational field, and are interpreted as representing a dendritic growth mode. The characteristic elongated and orientated sulfide nodules found in Agpalik signify trapped liquid of the latest stages of crystallization. Detailed mineralogical and chemical characterization of the Agpalik liquid-solid transformation products allow modelling of the entire crystallization history commencing with dendritic metal precipitation through an ultimate troilite-taenite-Cu eutectic, representing a crystallization range spanning approximately 1350-700 C.

Removal of Calcium from Scheelite Leaching Solution by Addition of CaSO4 Inoculating Crystals

NASA Astrophysics Data System (ADS)

Liu, Wenting; Li, Yongli; Zeng, Dewen; Li, Jiangtao; Zhao, Zhongwei

2018-04-01

In this work, the solubility behaviors of gypsum and anhydrite in the H2SO4-H3PO4-H2O system were investigated over the temperature range T = 30-80°C, and the results showed that the solubility of anhydrite was considerably lower than that of gypsum. On the basis of the differential solubilities of gypsum and anhydrite, a method was developed to remove calcium from the scheelite leaching solution by adding anhydrite as an inoculating crystal. The effects of the reaction time, concentration of the CaSO4 inoculating crystals, and temperature were investigated. With an addition of CaSO4 inoculating crystals at a concentration of 60 g/L, the Ca2+ concentration of the scheelite leaching solution decreased to a low level of approximately 0.76 g/L after 10 h at 70°C.

Large-area, near-infrared (IR) photonic crystals with colloidal gold nanoparticles embedding.

PubMed

Shukla, Shobha; Baev, Alexander; Jee, Hongsub; Hu, Rui; Burzynski, Ryszard; Yoon, Yong-Kyu; Prasad, Paras N

2010-04-01

A polymeric composite material composed of colloidal gold nanoparticles (<10 nm) and SU8 has been utilized for the fabrication of large-area, high-definition photonic crystal. We have successfully fabricated near-infrared photonic crystal slabs from composite materials using a combination of multiple beam interference lithography and reactive ion etching processes. Doping of colloidal gold nanoparticles into the SU8 photopolymer results in a better definition of structural features and hence in the enhancement of the optical properties of the fabricated photonic crystals. A 2D air hole array of triangular symmetry with a hole-to-hole pitch of approximately 500 nm has been successfully fabricated in a large circular area of 1 cm diameter. Resonant features observed in reflectance spectra of our slabs are found to depend on the exposure time, and can be tuned over a range of near-infrared frequencies.

Strategies for the coupling of global and local crystal growth models

NASA Astrophysics Data System (ADS)

Derby, Jeffrey J.; Lun, Lisa; Yeckel, Andrew

2007-05-01

The modular coupling of existing numerical codes to model crystal growth processes will provide for maximum effectiveness, capability, and flexibility. However, significant challenges are posed to make these coupled models mathematically self-consistent and algorithmically robust. This paper presents sample results from a coupling of the CrysVUn code, used here to compute furnace-scale heat transfer, and Cats2D, used to calculate melt fluid dynamics and phase-change phenomena, to form a global model for a Bridgman crystal growth system. However, the strategy used to implement the CrysVUn-Cats2D coupling is unreliable and inefficient. The implementation of under-relaxation within a block Gauss-Seidel iteration is shown to be ineffective for improving the coupling performance in a model one-dimensional problem representative of a melt crystal growth model. Ideas to overcome current convergence limitations using approximations to a full Newton iteration method are discussed.

Occurrence and genesis of Quaternary microbialitic tufa at Hammam Al Ali, Oman

NASA Astrophysics Data System (ADS)

Khalaf, Fikry I.

2017-05-01

Remnants of late Quaternary microbialitic tufa occurs within a shallow depression in the Hammam Al Ali hot spring area, which is located approximately 14.5 km to the southwest of Muscat, Oman. The tufa precipitated from hot spring water supersaturated with respect to calcium carbonate and is mostly of a porous phytogenic type, with occasional detrital and stromatolitic types. Microscopic and nanoscopic examination revealed that the tufa deposits developed through two successive processes of calcite precipitation, biotic and abiotic, preceded by limited precipitation of unstable aragonite. It is suggested that biologically mediated precipitation results in the construction of incomplete skeletal calcite crystals. The latter provide a base for classical physiochemical precipitation and, eventually, the development of complete sparry calcite crystals. The initiation of dendritic calcite crystals in the stromatolitic tufa as incomplete biogenic skeletal crystals and their characteristic growth pattern indicates that the tufa represents a clear example of hot spring calcitic microbialite.

Understanding Singlet and Triplet Excitons in Acene Crystals from First Principles

NASA Astrophysics Data System (ADS)

Rangel Gordillo, Tonatiuh; Sharifzadeh, Sahar; Kronik, Leeor; Neaton, Jeffrey

2014-03-01

Singlet fission, a process in which two triplet excitons are formed from a singlet exciton, has the potential to increase the solar cell efficiencies above 100%. Efficient singlet fission has been reported in larger acene crystals, such as tetracene and pentacene, in part attributable to their low-lying triplet energies. In this work, we use many-body perturbation theory within the GW approximation and the Bethe-Salpeter equation approach to compute quasiparticle gaps, low-lying singlet and and triplet excitations, and optical absorption spectra across the entire acene family of crystals, from benzene to hexacene. We closely examine the degree of localization and charge-transfer character of the low-lying singlets and triplets, and their sensitivity to crystal environment, and discuss implications for the efficiency of singlet fission in this systems. This work supported by DOE and computational resources provided by NERSC.

Liquid Crystalline Thermosets from Ester, Ester-imide, and Ester-amide Oligomers

NASA Technical Reports Server (NTRS)

Dingemans, Theodorus J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

2009-01-01

Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystaloligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oli-gomers are stable forup to an hour in the melt phase. They are highly processable by a variety of melt process shape forming and blending techniques. Once processed and shaped, the end-capped liquid crystal oigomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures.

Liquid drop stability for protein crystal growth in microgravity

NASA Technical Reports Server (NTRS)

Owen, Robert B.; Broom, Beth H.; Snyder, Robert S.; Daniel, Ron

1987-01-01

It is possible to grow protein crystals for biomedical research in microgravity by deploying a protein-rich solution from a syringe, forming a drop in which crystallization can occur with the proper degree of supersaturation. Drop stability is critical to the success of this research, due to the large drop sizes which can be achieved in space. In order to determine the type of syringe tips most suitable to support these large drops, tests were performed during brief periods of weightlessness onboard the NASA KC-135 low-gravity simulation aircraft. The drops were analyzed using three simple models in which the samples were approximated by modified pendulum and spring systems. It was concluded that the higher frequency systems were the most stable, indicating that of the syringes utilized, a disk-shaped configuration provided the most stable environment of low-gravity protein crystal growth.

Nucleation of protein crystals under the influence of solution shear flow.

PubMed

Penkova, Anita; Pan, Weichun; Hodjaoglu, Feyzim; Vekilov, Peter G

2006-09-01

Several recent theories and simulations have predicted that shear flow could enhance, or, conversely, suppress the nucleation of crystals from solution. Such modulations would offer a pathway for nucleation control and provide a novel explanation for numerous mysteries in nucleation research. For experimental tests of the effects of shear flow on protein crystal nucleation, we found that if a protein solution droplet of approximately 5 microL (2-3 mm diameter at base) is held on a hydrophobic substrate in an enclosed environment and in a quasi-uniform constant electric field of 2 to 6 kV cm(-1), a rotational flow with a maximum rate at the droplet top of approximately 10 microm s(-1) is induced. The shear rate varies from 10(-3) to 10(-1) s(-1). The likely mechanism of the rotational flow involves adsorption of the protein and amphiphylic buffer molecules on the air-water interface and their redistribution in the electric field, leading to nonuniform surface tension of the droplet and surface tension-driven flow. Observations of the number of nucleated crystals in 24- and 72-h experiments with the proteins ferritin, apoferritin, and lysozyme revealed that the crystals are typically nucleated at a certain radius of the droplet, that is, at a preferred shear rate. Variations of the rotational flow velocity resulted in suppression or enhancement of the total number of nucleated crystals of ferritin and apoferritin, while all solution flow rates were found to enhance lysozyme crystal nucleation. These observations show that shear flow may strongly affect nucleation, and that for some systems, an optimal flow velocity, leading to fastest nucleation, exists. Comparison with the predictions of theories and simulations suggest that the formation of ordered nuclei in a "normal" protein solution cannot be affected by such low shear rates. We conclude that the flow acts by helping or suppressing the formation of ordered nuclei within mesoscopic metastable dense liquid clusters. Such clusters were recently shown to exist in protein solutions and to constitute the first step in the nucleation mechanism of many protein and nonproteinsystems.

Effects of Microstructural Parameters on Creep of Nickel-Base Superalloy Single Crystals

NASA Technical Reports Server (NTRS)

MacKay, Rebecca A.; Gabb, Timothy P.; Nathal, Michael V.

2013-01-01

Microstructure-sensitive creep models have been developed for Ni-base superalloy single crystals. Creep rupture testing was conducted on fourteen single crystal alloys at two applied stress levels at each of two temperatures, 982 and 1093 C. The variation in creep lives among the different alloys could be explained with regression models containing relatively few microstructural parameters. At 982 C, gamma-gamma prime lattice mismatch, gamma prime volume fraction, and initial gamma prime size were statistically significant in explaining the creep rupture lives. At 1093 C, only lattice mismatch and gamma prime volume fraction were significant. These models could explain from 84 to 94 percent of the variation in creep lives, depending on test condition. Longer creep lives were associated with alloys having more negative lattice mismatch, lower gamma prime volume fractions, and finer gamma prime sizes. The gamma-gamma prime lattice mismatch exhibited the strongest influence of all the microstructural parameters at both temperatures. Although a majority of the alloys in this study were stable with respect to topologically close packed (TCP) phases, it appeared that up to approximately 2 vol% TCP phase did not affect the 1093 C creep lives under applied stresses that produced lives of approximately 200 to 300 h. In contrast, TCP phase contents of approximately 2 vol% were detrimental at lower applied stresses where creep lives were longer. A regression model was also developed for the as-heat treated initial gamma prime size; this model showed that gamma prime solvus temperature, gamma-gamma prime lattice mismatch, and bulk Re content were all statistically significant.

Active liquid-crystal deflector and lens with Fresnel structure

NASA Astrophysics Data System (ADS)

Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

2017-02-01

A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model.

PubMed

Russell, Sara S; Joy, Katherine H; Jeffries, Teresa E; Consolmagno, Guy J; Kearsley, Anton

2014-09-13

The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0.1 to approximately 10× chondritic (CI) abundance. Every plagioclase exhibited a positive Eu-anomaly, with Eu abundances of up to approximately 20×CI. Calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80×CI. Comparisons of our data with other lunar meteorites and Apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites, suggesting these samples did not all crystallize from a common magma source. Compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages. These observations may support other models of crust formation on the Moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model

PubMed Central

Russell, Sara S.; Joy, Katherine H.; Jeffries, Teresa E.; Consolmagno, Guy J.; Kearsley, Anton

2014-01-01

The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0.1 to approximately 10× chondritic (CI) abundance. Every plagioclase exhibited a positive Eu-anomaly, with Eu abundances of up to approximately 20×CI. Calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80×CI. Comparisons of our data with other lunar meteorites and Apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites, suggesting these samples did not all crystallize from a common magma source. Compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages. These observations may support other models of crust formation on the Moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation. PMID:25114312

Epstein-Barr virus and human immunodeficiency virus serological responses and viral burdens in HIV-infected patients treated with HAART

NASA Technical Reports Server (NTRS)

O'Sullivan, Cathal E.; Peng, RongSheng; Cole, Kelly Stefano; Montelaro, Ronald C.; Sturgeon, Timothy; Jenson, Hal B.; Ling, Paul D.; Butel, J. S. (Principal Investigator)

2002-01-01

Epstein-Barr virus (EBV) associated non-Hodgkin lymphoma is recognized as a complication of human immunodeficiency virus (HIV) infection. Little is known regarding the influence of highly active antiretroviral therapy (HAART) on the biology of EBV in this population. To characterize the EBV- and HIV-specific serological responses together with EBV DNA levels in a cohort of HIV-infected adults treated with HAART, a study was conducted to compare EBV and HIV serologies and EBV DNA copy number (DNAemia) over a 12-month period after the commencement of HAART. All patients were seropositive for EBV at baseline. Approximately 50% of patients had detectable EBV DNA at baseline, and 27/30 had detectable EBV DNA at some point over the follow-up period of 1 year. Changes in EBV DNA copy number over time for any individual were unpredictable. Significant increases in the levels of Epstein-Barr nuclear antigen (EBNA) and Epstein-Barr early antigen (EA) antibodies were demonstrated in the 17 patients who had a good response to HAART. Of 29 patients with paired samples tested, four-fold or greater increases in titers were detected for EA in 12/29 (41%), for EBNA in 7/29 (24%), for VCA-IgG in 4/29 (14%); four-fold decreases in titers were detected in 2/29 (7%) for EA and 12/29 (41%) for EBNA. A significant decline in the titer of anti-HIV antibodies was also demonstrated. It was concluded that patients with advanced HIV infection who respond to HAART have an increase in their EBV specific antibodies and a decrease in their HIV-specific antibodies. For the cohort overall, there was a transient increase in EBV DNA levels that had declined by 12 months. Copyright 2002 Wiley-Liss, Inc.

Left-right correlation in coupled F-center defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janesko, Benjamin G., E-mail: b.janesko@tcu.edu

This work explores how left-right correlation, a textbook problem in electronic structure theory, manifests in a textbook example of electrons trapped in crystal defects. I show that adjacent F-center defects in lithium fluoride display symptoms of “strong” left-right correlation, symptoms similar to those seen in stretched H{sub 2}. Simulations of UV/visible absorption spectra qualitatively fail to reproduce experiment unless left-right correlation is taken into account. This is of interest to both the electronic structure theory and crystal-defect communities. Theorists have a new well-behaved system to test their methods. Crystal-defect groups are cautioned that the approximations that successfully model single F-centersmore » may fail for adjacent F-centers.« less

Photoelectron emission from LiF surfaces by ultrashort electromagnetic pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acuna, M. A.; Gravielle, M. S.; Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires

2011-03-15

Energy- and angle-resolved electron emission spectra produced by incidence of ultrashort electromagnetic pulses on a LiF(001) surface are studied by employing a distorted-wave method named the crystal surface-Volkov (CSV) approximation. The theory makes use of the Volkov phase to describe the action of the external electric field on the emitted electron, while the electron-surface interaction is represented within the tight-binding model. The CSV approach is applied to investigate the effects introduced by the crystal lattice when the electric field is oriented parallel to the surface plane. These effects are essentially governed by the vector potential of the external field, whilemore » the influence of the crystal orientation was found to be negligible.« less

Oxygen isotope exchange between refractory inclusion in Allende and solar nebula gas.

PubMed

Yurimoto, H; Ito, M; Nagasawa, H

1998-12-04

A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope composition (approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI. Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula.

Oxygen isotope exchange between refractory inclusion in allende and solar nebula Gas

PubMed

Yurimoto; Ito; Nagasawa

1998-12-04

A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope compositions ( approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI. Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula.

Topological phase transitions from Harper to Fibonacci crystals

NASA Astrophysics Data System (ADS)

Amit, Guy; Dana, Itzhack

2018-02-01

Topological properties of Harper and generalized Fibonacci chains are studied in crystalline cases, i.e., for rational values of the modulation frequency. The Harper and Fibonacci crystals at fixed frequency are connected by an interpolating one-parameter Hamiltonian. As the parameter is varied, one observes topological phase transitions, i.e., changes in the Chern integers of two bands due to the degeneracy of these bands at some parameter value. For small frequency, corresponding to a semiclassical regime, the degeneracies are shown to occur when the average energy of the two bands is approximately equal to the energy of the classical separatrix. Spectral and topological features of the Fibonacci crystal for small frequency leave a clear imprint on the corresponding Hofstadter butterfly for arbitrary frequency.

Highly mobile type II twin boundary in Ni-Mn-Ga five-layered martensite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sozinov, A.; Lanska, N.; Soroka, A.

2011-09-19

Twin relationships and stress-induced reorientation were studied in Ni{sub 2}Mn{sub 1.14}Ga{sub 0.86} single crystal with five-layered modulated martensite crystal structure. Very low twinning stress of about 0.1 MPa was found for twin boundaries which deviated a few degrees from the (011) crystallographic plane. However, twin boundaries oriented exactly parallel to the (011) plane exhibited considerably higher level of twinning stress, above 1 MPa. X-ray diffraction experiments and calculations based on approximation of the martensite crystal lattice as a tetragonal lattice with a slight monoclinic distortion identified the two different kinds of twin interfaces as type II and type I twinmore » boundaries.« less

Re-solution of xenon clusters in plutonium dioxide under the collision cascade impact: A molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Seitov, D. D.; Nekrasov, K. A.; Kupryazhkin, A. Ya.; Gupta, S. K.; Akilbekov, A. T.

2017-09-01

The interaction of xenon clusters with the collision cascades in the PuO2 crystals is investigated using the molecular dynamics simulation and the approximation of the pair interaction potentials. The potentials of interaction of Xe atoms with the surrounding particles in the crystal lattice are suggested, that are valid in the range of high collision energies. The cascades created by the recoil 235U ions formed as the plutonium α-decay product are considered, and the influence of such cascades on the structure of the xenon clusters is analyzed. It is shown, that the cascade-cluster interaction leads to release of the xenon atoms from the clusters and their subsequent re-solution in the crystal bulk.

User’s Guide for an Optical Contrast Seeker Monte Carlo Terminal Homing Simulation

DTIC Science & Technology

1975-05-14

AG sin X ) Eq. 2.16 33 Acceleration Normal to Plane .. X (Boresignt) G. Plane containing mass unbalance centrotd ~YG FIGURE 3.28. Inner Gimbal View...ill# .L01 0.090 jNi FORM -1.000 1. CJ2 .315 C.0 3 0.000 UNICORN -1.0100 1. U000 2,4kp1 .12J C.GG0 JN.’FORM -1.000100 14L2 -. 4.8 0.00a .JKIFORM -1.000...fu 1. rj m N. I At1 -- c2 0 0* 4- 0 W uI-WL UL w I~ f :.VPI *4 *.* .. 4 C, : IV 1A ag oo ,- * I4 1, %An Q. cc Go coc oC cVCa: .ato to o 1 o I a

Defensiveness, trait anxiety, and Epstein-Barr viral capsid antigen antibody titers in healthy college students.

PubMed

Esterling, B A; Antoni, M H; Kumar, M; Schneiderman, N

1993-03-01

The relationship of individual differences in repressive coping styles with differences in antibody titer to Epstein-Barr viral capsid antigen (EBV-VCA) were investigated in a normal, healthy college population made up of people previously exposed to EBV. Each of 54 1st-year undergraduates completed a battery of physical-status questions and items pertaining to potential behavioral immunomodulatory confounds, along with the Taylor Manifest Anxiety Scale (T-MAS) and the Marlowe-Crowne Social Desirability Scale (MC-SDS). Ss reporting high and middle levels of anxiety had higher antibody titers to EBV, suggesting poorer immune control over the latent virus, as compared with the low-anxious group. Similarly, high-defensive Ss had higher antibody titers than their low-defensive counterparts, and neither group differed from the middle group.

1 : 2 Adducts of copper(I) halides with 1,2-bis(di-2-pyridylphosphino)ethane: solid state and solution structural studies and antitumour activity.

PubMed

Bowen, Richard J; Navarro, Maribel; Shearwood, Anne-Marie J; Healy, Peter C; Skelton, Brian W; Filipovska, Aleksandra; Berners-Price, Susan J

2009-12-28

The 1 : 2 adducts of copper(I) halides with 1,2-bis(2-pyridylphosphino)ethane (d2pype) have been synthesized and solution properties characterized by variable temperature (1)H, (31)P and (65)Cu NMR spectroscopy. Single-crystal structure determinations for the chloride, bromide and iodide complexes show these to crystallize from acetonitrile in the triclinic space group P1 as isostructural centrosymmetric dimers [(d2pype)Cu(mu-d2pype)(2)Cu(d2pype)]X(2).(solvent) with a approximately 12.6, b approximately 12.7, c approximately 15.3 A, alpha approximately 84, beta approximately 67, gamma approximately 84 degrees. In contrast to the analogous AuCl:2(d2pype) and AgNO(3):2(d2pype) adducts, in solution these CuX:2(d2pype) adducts (where X = Cl, Br and I) exist almost exclusively as bis-chelated monomeric [Cu(d2pype)(2)]X; evidence for an equilibrium between monomeric and dimeric forms is detected only for the CuCl adduct in methanol. Cytotoxicity studies in two human breast cancer lines and two matched liver progenitor cell lines indicate that [Cu(d2pype)(2)]Cl is non selectively toxic to both non-tumourigenic and tumourigenic cells. However, the analogous Au(I) compound [Au(d2pype)(2)]Cl, is toxic to highly tumourigenic cells and more selective in its toxicity to tumourigenic cells compared to non-tumourigenic cells. The significance of these results to the further development of selective, mitochondria-targeted, Au(I) antitumour complexes is discussed.

Measurements and properties of ice particles and carbon dioxide bubbles in aqueous mixture utilizing optical techniques

NASA Astrophysics Data System (ADS)

Diallo, Amadou O.

Optical techniques are used to determine the size, shape and many other properties of particles ranging from the micro to a nano-level. These techniques have endless applications. This research is based on a project assigned by a "Vendor" that wants anonymity. The Leica optical microscope and the Dark Field Polarizing Metallurgical Microscope is used to determine the size and count of ice crystals (Vendors products) in multiple time frames. Since the ice temperature influences, its symmetry and the shape is subject to changes at room temperature (300 K) and the atmospheric pressure that is exerted on the ice crystals varies. The ice crystals are in a mixture of water, electrolytes and carbon dioxide with the optical spectroscopy (Qpod2) and Spectra suite, the optical density of the ice crystals is established from the absorbance and transmission measurements. The optical density in this case is also referred to as absorption; it is plotted with respect to a frequency (GHz), wavelength (nm) or Raman shift (1/cm) which shows the light colliding with the ice particles and CO2. Depending on the peaks positions, it is possible to profile the ice crystal sizes using a mean distribution plots. The region of absorbency wavelength expected for the ice is in the visible range; the water molecules in the (UV) Ultra-violet range and the CO2 in the (IR) infrared region. It is also possible to obtain the reflection and transmission output as a percentage change with the wavelengths ranging from 200 to 1100 nm. The refractive index of the ice can be correlated to the density based on the optical acoustic theorem, or Mie Scattering Theory. The viscosity of the ice crystals and the solutions from which the ice crystals are made of as well are recorded with the SV-10 viscometer. The baseline viscosity is used as reference and set lower than that of the ice crystals. The Zeta potential of the particles present in the mixture are approximated by first finding the viscosity of the solution where the pH level contribute to the surface charges, afterward use Stoke's diameter to compute the settling velocity of the bubbles, or alternatively record it under the microscope. With those parameters in hand the surface charge of the bubble (zeta potential) is approximated.

A Crystal Plasticity Model of Fatigue of Dissimilar Magnesium Alloy Bi-Crystals

NASA Astrophysics Data System (ADS)

Knight, Simon

A crystal plasticity finite element (CPFE) model was applied to the fatigue deformation of dissimilar Mg alloy bi-crystals. The mesoscopic stress-strain and microscopic slip and twinning behaviour of the model were first validated with experimental tension and compression data of pure Mg single crystals. High-cycle fatigue (HCF) simulations up to 1000 cycles were then used to systematically examine the effect of different textures on the cyclic deformation behavior of Mg AZ31-AZ80 bi-crystals at room-temperature. Fatigue behaviour was characterized in terms of the mesoscopic average stress-strain response and the evolution of the microscopic deformation (slip/twin activity). The model captures load asymmetry, cyclic hardening/softening and ratcheting. However, the model did not capture stress concentrations at the grain boundary (GB) for the grain shapes considered. Either basal slip or tensile twinning was activated for any given orientation. When the soft AZ31 grain is oriented for basal slip almost all the shear strain is contained in that grain and has approximately ten times more accumulated shear strain than the other orientations. The results reveal there is a strong effect from orientation combinations on the cyclic deformation wherein a "hard" orientation shields a "soft" orientation from strain. When the AZ80 grain is oriented for basal slip and the AZ31 grain is oriented for tensile twinning the bi-crystal is soft, but only in one direction since twinning is a polar mechanism. Approximately half as much accumulated shear strain occurs when both grains are oriented for twinning. The slip and twinning systems quickly harden in AZ31 in the first few hundred cycles and the shear strain amplitudes quickly devolve from values between 10-6 - 10-4 to around 10-7; values which would be difficult to resolve experimentally. The results were then extended to the possible effects on the fatigue behaviour of an AZ31-AZ80 dissimilar weld idealized as an AZ31-AZ80 bi-crystal. It is predicted that the worst fatigue behaviour would occur when one grain is oriented for basal slip: AZ31 grain, results in strain localization; AZ80 grain, results in an increase in twin boundaries and irreversible deformation in an AZ31 grain.

Intense Photosensitized Emission from Stoichiometric Compounds Featuring Mn(2+) in Seven- and Eightfold Coordination Environments.

PubMed

Reid, Howard O. N.; Kahwa, Ishenkumba A.; White, Andrew J. P.; Williams, David J.

1998-07-27

Synthetic, structural and luminescence studies of stoichiometric crown ether compounds of Mn(2+) in well-defined coordination environments were undertaken in an effort to understand the origin of emitting crystal defects found in cubic F23 [(K18C6)(4)MnBr(4)][TlBr(4)](2) crystals (Fender, N. S.; et al. Inorg. Chem. 1997, 36, 5539). The new compound [Mn(12C4)(2)][MnBr(4)](2)[N(CH(3))(4)](2) (3) features Mn(2+) ions in eight- and fourfold coordination environments of [Mn(12C4)(2)](2+) and MnBr(4)(2)(-) respectively, while Mn(2+) in [Mn(15C5)(H(2)O)(2)][TlBr(5)] (4) is in the sevenfold coordination polyhedron of [Mn(15C5)(H(2)O)(2)](2+). Crystal data for 3: monoclinic, P2(1)/c (No. 14); a = 14.131(3) Å, b = 12.158(1) Å, c = 14.239(2) Å, beta = 110.37(1) degrees, Z = 2, R1 = 0.039 and wR2 = 0.083. For 3, long-lived emission (77 K decay rate approximately 3 x 10 s(-)(1)) from [Mn(12C4)(2)](2+) (the first for eight-coordinate Mn(2+) in stoichiometric compounds) is observed (lambda(max) approximately 546 nm) along with that of the sensitizing MnBr(4)(2)(-) (lambda(max) approximately 513 nm), which is partially quenched. Emission from the seven-coordinate [Mn(15C5)(H(2)O)(2)](2+) species of 4 and [Mn(15C5)(H(2)O)(2)][MnBr(4)] (the first for seven-coordinate Mn(2+) in stoichiometric compounds) peaks at lambda(max) approximately 592 nm. Unusually intense absorptions attributable to the seven-coordinate species are observed at 317 ((2)T(2)((2)I) <-- (6)A(1)), 342 ((4)T(1)((4)P) <-- (6)A(1)), 406 ((4)E((4)G) <-- (6)A(1)), and 531 ((4)T(1)((4)G) <-- (6)A(1)) nm.

Summation rules for a fully nonlocal energy-based quasicontinuum method

NASA Astrophysics Data System (ADS)

Amelang, J. S.; Venturini, G. N.; Kochmann, D. M.

2015-09-01

The quasicontinuum (QC) method coarse-grains crystalline atomic ensembles in order to bridge the scales from individual atoms to the micro- and mesoscales. A crucial cornerstone of all QC techniques, summation or quadrature rules efficiently approximate the thermodynamic quantities of interest. Here, we investigate summation rules for a fully nonlocal, energy-based QC method to approximate the total Hamiltonian of a crystalline atomic ensemble by a weighted sum over a small subset of all atoms in the crystal lattice. Our formulation does not conceptually differentiate between atomistic and coarse-grained regions and thus allows for seamless bridging without domain-coupling interfaces. We review traditional summation rules and discuss their strengths and weaknesses with a focus on energy approximation errors and spurious force artifacts. Moreover, we introduce summation rules which produce no residual or spurious force artifacts in centrosymmetric crystals in the large-element limit under arbitrary affine deformations in two dimensions (and marginal force artifacts in three dimensions), while allowing us to seamlessly bridge to full atomistics. Through a comprehensive suite of examples with spatially non-uniform QC discretizations in two and three dimensions, we compare the accuracy of the new scheme to various previous ones. Our results confirm that the new summation rules exhibit significantly smaller force artifacts and energy approximation errors. Our numerical benchmark examples include the calculation of elastic constants from completely random QC meshes and the inhomogeneous deformation of aggressively coarse-grained crystals containing nano-voids. In the elastic regime, we directly compare QC results to those of full atomistics to assess global and local errors in complex QC simulations. Going beyond elasticity, we illustrate the performance of the energy-based QC method with the new second-order summation rule by the help of nanoindentation examples with automatic mesh adaptation. Overall, our findings provide guidelines for the selection of summation rules for the fully nonlocal energy-based QC method.

Single Mode Air-Clad Single Crystal Sapphire Optical Fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, Cary; Homa, Dan; Yu, Zhihao

The observation of single mode propagation in an air-clad single crystal sapphire optical fiber at wavelengths at and above 783 nm is presented for the first time. A high-temperature wet acid etching method was used to reduce the diameter of a 10 cm length of commercially-sourced sapphire fiber from 125 micrometers to 6.5 micrometers, and far-field imaging provided modal information at intervals as the fiber diameter decreased. Modal volume was shown to decrease with decreasing diameter, and single mode behavior was observed at the minimum diameter achieved. While weakly-guiding approximations are generally inaccurate for low modal volume optical fiber withmore » high core-cladding refractive index disparity, consistency between these approximations and experimental results was observed when the effective numerical aperture was measured and substituted for the theoretical numerical aperture in weakly-guiding approximation calculations. With the demonstration of very low modal volume in sapphire at fiber diameters much larger than anticipated by legacy calculations, the resolution of sapphire fiber distributed sensors may be increased and other sensing schemes requiring very low modal volume, such as fiber Bragg gratings, may be realized in extreme environment applications.« less

Single Mode Air-Clad Single Crystal Sapphire Optical Fiber

DOE PAGES

Hill, Cary; Homa, Dan; Yu, Zhihao; ...

2017-05-03

The observation of single mode propagation in an air-clad single crystal sapphire optical fiber at wavelengths at and above 783 nm is presented for the first time. A high-temperature wet acid etching method was used to reduce the diameter of a 10 cm length of commercially-sourced sapphire fiber from 125 micrometers to 6.5 micrometers, and far-field imaging provided modal information at intervals as the fiber diameter decreased. Modal volume was shown to decrease with decreasing diameter, and single mode behavior was observed at the minimum diameter achieved. While weakly-guiding approximations are generally inaccurate for low modal volume optical fiber withmore » high core-cladding refractive index disparity, consistency between these approximations and experimental results was observed when the effective numerical aperture was measured and substituted for the theoretical numerical aperture in weakly-guiding approximation calculations. With the demonstration of very low modal volume in sapphire at fiber diameters much larger than anticipated by legacy calculations, the resolution of sapphire fiber distributed sensors may be increased and other sensing schemes requiring very low modal volume, such as fiber Bragg gratings, may be realized in extreme environment applications.« less

Liquid Crystalline Thermosets from Ester, Ester-Imide, and Ester-Amide Oligomers

NASA Technical Reports Server (NTRS)

Dingemans, Theodornus J. (Inventor); Weiser, Erik S. (Inventor); SaintClair, Terry L. (Inventor)

2005-01-01

Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,OOO grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end- capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

Liquid crystalline thermosets from ester, ester-imide, and ester-amide oligomers

NASA Technical Reports Server (NTRS)

Dingemans, Theodorous J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

2005-01-01

Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end-capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

Structure and morphology of magnetite anaerobically-produced by a marine magnetotactic bacterium and a dissimilatory iron-reducing bacterium

USGS Publications Warehouse

Sparks, N.H.C.; Mann, S.; Bazylinski, D.A.; Lovley, D.R.; Jannasch, H.W.; Frankel, R.B.

1990-01-01

Intracellular crystals of magnetite synthesized by cells of the magnetotactic vibroid organism, MV-1, and extracellular crystals of magnetite produced by the non-magnetotactic dissimilatory iron-reducing bacterium strain GS-15, were examined using high-resolution transmission electron microscopy, electron diffraction and 57Fe Mo??ssbauer spectroscopy. The magnetotactic bacterium contained a single chain of approximately 10 crystals aligned along the long axis of the cell. The crystals were essentially pure stoichiometric magnetite. When viewed along the crystal long axis the particles had a hexagonal cross-section whereas side-on they appeared as rectangules or truncated rectangles of average dimension, 53 ?? 35 nm. These findings are explained in terms of a three-dimensional morphology comprising a hexagonal prism of {110} faces which are capped and truncated by {111} end faces. Electron diffraction and lattice imaging studies indicated that the particles were structurally well-defined single crystals. In contrast, magnetite particles produced by the strain, GS-15 were irregular in shape and had smaller mean dimensions (14 nm). Single crystals were imaged but these were not of high structural perfection. These results highlight the influence of intracellular control on the crystallochemical specificity of bacterial magnetites. The characterization of these crystals is important in aiding the identification of biogenic magnetic materials in paleomagnetism and in studies of sediment magnetization. ?? 1990.

Interface and facet control during Czochralski growth of (111) InSb crystals for cost reduction and yield improvement of IR focal plane array substrates

NASA Astrophysics Data System (ADS)

Gray, Nathan W.; Perez-Rubio, Victor; Bolke, Joseph G.; Alexander, W. B.

2014-10-01

Focal plane arrays (FPAs) made on InSb wafers are the key cost-driving component in IR imaging systems. The electronic and crystallographic properties of the wafer directly determine the imaging device performance. The "facet effect" describes the non-uniform electronic properties of crystals resulting from anisotropic dopant segregation during bulk growth. When the segregation coefficient of dopant impurities changes notably across the melt/solid interface of a growing crystal the result is non-uniform electronic properties across wafers made from these crystals. The effect is more pronounced in InSb crystals grown on the (111) axis compared with other orientations and crystal systems. FPA devices made on these wafers suffer costly yield hits due to inconsistent device response and performance. Historically, InSb crystal growers have grown approximately 9-19 degree off-axis from the (111) to avoid the facet effect and produced wafers with improved uniformity of electronic properties. It has been shown by researchers in the 1960s that control of the facet effect can produce uniform small diameter crystals. In this paper, we share results employing a process that controls the facet effect when growing large diameter crystals from which 4, 5, and 6" wafers can be manufactured. The process change resulted in an increase in wafers yielded per crystal by several times, all with high crystal quality and uniform electronic properties. Since the crystals are grown on the (111) axis, manufacturing (111) oriented wafers is straightforward with standard semiconductor equipment and processes common to the high-volume silicon wafer industry. These benefits result in significant manufacturing cost savings and increased value to our customers.

Trisphenalenyl-based neutral radical molecular conductor.

PubMed

Pal, Sushanta K; Itkis, Mikhail E; Tham, Fook S; Reed, Robert W; Oakley, Richard T; Haddon, Robert C

2008-03-26

We report the preparation, crystallization, and solid-state characterization of the first member of a new family of tris(1,9-disubstituted phenalenyl)silicon neutral radicals. In the solid state, the radical packs as weak partial pi-dimers with intermolecular carbon...carbon contacts that fall at the van der Waals atomic separation. Magnetic susceptibility measurements indicate approximately 0.7 Curie spins per molecule from room temperature down to 50 K, below which antiferromagnetic coupling becomes apparent; the compound has a room-temperature single-crystal conductivity of sigmaRT = 2.4 x 10(-6) S cm(-1).

Tight-binding calculation of radiation loss in photonic crystal CROW.

PubMed

Ma, Jing; Martínez, Luis Javier; Fan, Shanhui; Povinelli, Michelle L

2013-01-28

The tight binding approximation (TBA) is used to relate the intrinsic, radiation loss of a coupled resonator optical waveguide (CROW) to that of a single constituent resonator within a light cone picture. We verify the validity of the TBA via direct, full-field simulation of CROWs based on the L2 photonic crystal cavity. The TBA predicts that the quality factor of the CROW increases with that of the isolated cavity. Moreover, our results provide a method to design CROWs with low intrinsic loss across the entire waveguide band.

Controlling Chain Conformations of High-k Fluoropolymer Dielectrics to Enhance Charge Mobilities in Rubrene Single-Crystal Field-Effect Transistors.

PubMed

Adhikari, Jwala M; Gadinski, Matthew R; Li, Qi; Sun, Kaige G; Reyes-Martinez, Marcos A; Iagodkine, Elissei; Briseno, Alejandro L; Jackson, Thomas N; Wang, Qing; Gomez, Enrique D

2016-12-01

A novel photopatternable high-k fluoropolymer, poly(vinylidene fluoride-bromotrifluoroethylene) P(VDF-BTFE), with a dielectric constant (k) between 8 and 11 is demonstrated in thin-film transistors. Crosslinking P(VDF-BTFE) reduces energetic disorder at the dielectric-semiconductor interface by controlling the chain conformations of P(VDF-BTFE), thereby leading to approximately a threefold enhancement in the charge mobility of rubrene single-crystal field-effect transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An experimental and numerical study of the light scattering properties of ice crystals with black carbon inclusions

NASA Astrophysics Data System (ADS)

Arienti, Marco; Geier, Manfred; Yang, Xiaoyuan; Orcutt, John; Zenker, Jake; Brooks, Sarah D.

2018-05-01

We investigate the optical properties of ice crystals nucleated on atmospheric black carbon (BC). The parameters examined in this study are the shape of the ice crystal, the volume fraction of the BC inclusion, and its location inside the crystal. We report on new spectrometer measurements of forward scattering and backward polarization from ice crystals nucleated on BC particles and grown under laboratory-controlled conditions. Data from the Cloud and Aerosol Spectrometer with Polarization (CASPOL) are used for direct comparison with single-particle calculations of the scattering phase matrix. Geometrical optics and discrete dipole approximation techniques are jointly used to provide the best compromise of flexibility and accuracy over a broad range of size parameters. Together with the interpretation of the trends revealed by the CASPOL measurements, the numerical results confirm previous reports on absorption cross-section magnification in the visible light range. Even taking into account effects of crystal shape and inclusion position, the ratio between absorption cross-section of the compound particle and the absorption cross-section of the BC inclusion alone (the absorption magnification) has a lower bound of 1.5; this value increases to 1.7 if the inclusion is centered with respect to the crystal. The simple model of BC-ice particle presented here also offers new insights on the effect of the relative position of the BC inclusion with respect to the crystal's outer surfaces, the shape of the crystal, and its size.

Kinetic Roughening and Energetics of Tetragonal Lysozyme Crystal Growth: A Preliminary Atomic Force Microscopy Investigation

NASA Technical Reports Server (NTRS)

Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

2004-01-01

We examined particulars of crystal growth from measurements obtained at both microscopic and molecular levels. The crystal growth measurements performed at the microscopic level are well characterized by a model that balances the flux of macromolecules towards the crystal surface with the flux of the crystal surface. Numerical evaluation of model with measurements of crystal growth, in time, provided accurate estimates for the average growth velocities. Growth velocities thus obtained were also interpreted using well-established phenomenological theories. Moreover, we find that microscopic measurements of growth velocity measurements obtained as a function of temperature best characterizes changes in crystal growth modes, when present. We also examined the possibility of detecting a change in crystal growth modes at the molecular level using atomic force microscopy, AFM. From preliminary AFM measurements performed at various supersaturations, we find that magnitude of surface height fluctuations, h(x), increases with supersaturation. Further examination of surface height fluctuations using methods established for fluctuation spectroscopy also enabled the discovery of the existence of a characteristic length, c, which may possibly determine the mode of crystal growth. Although the results are preliminary, we establish the non- critical divergence of 5 and the root-mean-square (rms) magnitude of height-height fluctuations as the kinetic roughening transition temperatures are approached. Moreover, we also examine approximate models for interpreting the non-critical behavior of both 6 and rms magnitude of height-height fluctuations, as the solution supersaturation is increased towards the kinetic roughening supersaturation.

Weak crystallization theory of metallic alloys

DOE PAGES

Martin, Ivar; Gopalakrishnan, Sarang; Demler, Eugene A.

2016-06-20

Crystallization is one of the most familiar, but hardest to analyze, phase transitions. The principal reason is that crystallization typically occurs via a strongly first-order phase transition, and thus rigorous treatment would require comparing energies of an infinite number of possible crystalline states with the energy of liquid. A great simplification occurs when crystallization transition happens to be weakly first order. In this case, weak crystallization theory, based on unbiased Ginzburg-Landau expansion, can be applied. Even beyond its strict range of validity, it has been a useful qualitative tool for understanding crystallization. In its standard form, however, weak crystallization theorymore » cannot explain the existence of a majority of observed crystalline and quasicrystalline states. Here we extend the weak crystallization theory to the case of metallic alloys. In this paper, we identify a singular effect of itinerant electrons on the form of weak crystallization free energy. It is geometric in nature, generating strong dependence of free energy on the angles between ordering wave vectors of ionic density. That leads to stabilization of fcc, rhombohedral, and icosahedral quasicrystalline (iQC) phases, which are absent in the generic theory with only local interactions. Finally, as an application, we find the condition for stability of iQC that is consistent with the Hume-Rothery rules known empirically for the majority of stable iQC; namely, the length of the primary Bragg-peak wave vector is approximately equal to the diameter of the Fermi sphere.« less

Ion and Bio-Selective Membrane Electrodes.

ERIC Educational Resources Information Center

Rechnitz, Garry A.

1983-01-01

Discusses topics on membrane electrodes corresponding to approximately six hours of lecture time. These include glass, liquid, crystal, gas-sensing membrane electrodes as well as enzyme and other bioselective membrane electrodes. Instructional strategies and other topics which might be discussed are provided. (JN)

Anisotropic Energy Transport Properties of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)

NASA Astrophysics Data System (ADS)

Kroonblawd, Matthew P.

Anisotropic energy transport properties were determined theoretically for crystals of the insensitive explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using molecular dynamics simulations. Determination of these properties is necessary for the analysis and interpretation of molecular dynamics predictions of transient processes such as shock response and hot spot formation/relaxation and is similarly important for the accurate parameterization of meso- and continuum-scale engineering models aimed at understanding complex processes such as ignition and growth leading to detonation. TATB crystal exhibits a graphitic-like layered packing structure with a two-dimensional hydrogen-bonding network that forms within, but not between, the molecule-thick layers that comprise the crystal. This structure is thought to be the primary factor behind the significant anisotropy in many physical properties of TATB crystals. Anisotropic thermal conductivity coefficients were determined for initially defect-free and defective TATB crystals and isotropic values were determined for the liquid at temperatures and pressures up to (1800 K, 2.0 GPa). The room temperature, atmospheric pressure thermal conductivity for TATB is predicted to be generally greater and more anisotropic than the thermal conductivities of other molecular explosives; conduction within the layers is approximately 70% greater than conduction between the layers. The conductivity is predicted to decrease with temperature approximately as λ ∝ 1/T over the interval 200 K ≤ T ≤ 700 K and to linearly increase with pressure up to 2.5 GPa. Direction-dependent relaxation of idealized one-dimensional hot spots was studied. Results from hot spot relaxation simulations were compared with and fit to solutions for the one-dimensional diffusive heat equation by treating the thermal di.usivity as a parameter to assess the validity of using continuum models to describe heat transport in TATB on length scales below 10 nm. A dissipative particle dynamics (DPD) at constant energy (DPDE) coarsegrained model is developed for TATB and applied to micron-scale shock simulations wherein the predicted shock response is shown to be highly sensitive to a model parameter controlling kinetics of energy transport between inter- and intramolecular degrees of freedom. A generalized crystal-cutting method is developed that enables facile construction of three-dimensionally periodic simulation cells containing arbitrarily oriented single crystals and crystal-crystal interfaces for materials of arbitrary symmetry class. Strategies for non-uniform sampling of molecular dynamics simulations of transient phenomena are proposed that have the potential to drastically reduce data storage costs.

Theoretical and experimental analyses to determine the effects of crystal orientation and grain size on the thermoelectric properties of oblique deposited bismuth telluride thin films

NASA Astrophysics Data System (ADS)

Morikawa, Satoshi; Satake, Yuji; Takashiri, Masayuki

2018-06-01

The effects of crystal orientation and grain size on the thermoelectric properties of Bi2Te3 thin films were investigated by conducting experimental and theoretical analyses. To vary the crystal orientation and grain size, we performed oblique deposition, followed by thermal annealing treatment. The crystal orientation decreased as the oblique angle was increased, while the grain size was not changed significantly. The thermoelectric properties were measured at room temperature. A theoretical analysis was performed using a first principles method based on density functional theory. Then the semi-classical Boltzmann transport equation was used in the relaxation time approximation, with the effect of grain size included. Furthermore, the effect of crystal orientation was included in the calculation based on a simple semi-experimental model. A maximum power factor of 11.6 µW/(cm·K2) was obtained at an oblique angle of 40°. The calculated thermoelectric properties were in very good agreement with the experimentally measured values.

Large single crystal growth, transport property, and spectroscopic characterizations of three-dimensional Dirac semimetal Cd3As2.

PubMed

Sankar, R; Neupane, M; Xu, S-Y; Butler, C J; Zeljkovic, I; Panneer Muthuselvam, I; Huang, F-T; Guo, S-T; Karna, Sunil K; Chu, M-W; Lee, W L; Lin, M-T; Jayavel, R; Madhavan, V; Hasan, M Z; Chou, F C

2015-08-14

The three dimensional (3D) Dirac semimetal is a new quantum state of matter that has attracted much attention recently in physics and material science. Here, we report on the growth of large plate-like single crystals of Cd3As2 in two major orientations by a self-selecting vapor growth (SSVG) method, and the optimum growth conditions have been experimentally determined. The crystalline imperfections and electrical properties of the crystals were examined with transmission electron microscopy (TEM), scanning tunneling microscopy (STM), and transport property measurements. This SSVG method makes it possible to control the as-grown crystal compositions with excess Cd or As leading to mobilities near 5-10(5) cm(2)V(-1)s(-1). Zn-doping can effectively reduce the carrier density to reach the maximum residual resistivity ratio (RRRρ300K/ρ5K) of 7.6. A vacuum-cleaved single crystal has been investigated using angle-resolved photoemission spectroscopy (ARPES) to reveal a single Dirac cone near the center of the surface Brillouin zone with a binding energy of approximately 200 meV.

Experimental study of strong nonlinear-optics effects in liquid crystals

NASA Astrophysics Data System (ADS)

Darbin, S. D.; Arakelyan, S. M.; Cheung, M. M.; Shen, Y. R.

1984-07-01

Nonlinear optical effects that arise in nematic liquid crystals as a result of a change in the index of refraction induced by a laser field are considered. Since the resultant nonlinearity is extremely high, the approximation of perturbation theory cannot be used in calculations. However, the change in refractive index results mainly in phase advance as waves propagate through a thin film of liquid crystal, while the change of intensity is significant. Moreover, if there is no change in polarization of the pumping field, calculations are relatively simple. An investigation is made of the propagation of a cross sectionally bounded laser beam through a homeotropically oriented liquid crystal, giving rise to spatial phase modulation of emission. When the intensity of the laser beam exceeds a certain value, a system of aberation rings is observed in the output radiation. Effects of dynamic self-diffraction accompanying degenerate four-wave mixing when a change in refractive index is induced in a homeotropic liquid crystal film, and optical bistability in a nonlinear Fabry-Perot optical cavity, as well as generation of a self-oscillatory state in such a resonator are discussed.

Crystallization dynamics and interface stability of strontium titanate thin films on silicon.

PubMed

Hanzig, Florian; Hanzig, Juliane; Mehner, Erik; Richter, Carsten; Veselý, Jozef; Stöcker, Hartmut; Abendroth, Barbara; Motylenko, Mykhaylo; Klemm, Volker; Novikov, Dmitri; Meyer, Dirk C

2015-04-01

Different physical vapor deposition methods have been used to fabricate strontium titanate thin films. Within the binary phase diagram of SrO and TiO 2 the stoichiometry ranges from Ti rich to Sr rich, respectively. The crystallization of these amorphous SrTiO 3 layers is investigated by in situ grazing-incidence X-ray diffraction using synchrotron radiation. The crystallization dynamics and evolution of the lattice constants as well as crystallite sizes of the SrTiO 3 layers were determined for temperatures up to 1223 K under atmospheric conditions applying different heating rates. At approximately 473 K, crystallization of perovskite-type SrTiO 3 is initiated for Sr-rich electron beam evaporated layers, whereas Sr-depleted sputter-deposited thin films crystallize at 739 K. During annealing, a significant diffusion of Si from the substrate into the SrTiO 3 layers occurs in the case of Sr-rich composition. This leads to the formation of secondary silicate phases which are observed by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy.

High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide.

PubMed

Marichy, Catherine; Muller, Nicolas; Froufe-Pérez, Luis S; Scheffold, Frank

2016-02-25

Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold refractive index contrast that depends on the crystal structure. In the case of the so-called woodpile photonic crystals this threshold is comparably low, approximately 1.9 for the direct structure. Therefore direct or inverted woodpiles made of high refractive index materials like silicon, germanium or titanium dioxide are sought after. Here we show that, by combining multiphoton lithography and atomic layer deposition, we can achieve a direct inversion of polymer templates into TiO2 based photonic crystals. The obtained structures show remarkable optical properties in the near-infrared region with almost perfect specular reflectance, a transmission dip close to the detection limit and a Bragg length comparable to the lattice constant.

UV-light-induced one-color and two-color photorefractive effects in congruent and near-stoichiometric LiNbO 3:Mg crystals

NASA Astrophysics Data System (ADS)

Qiao, Haijun; Xu, Jingjun; Tomita, Yasuo; Zhu, Dengsong; Fu, Bo; Zhang, Guoquan; Zhang, Guangyin

2007-03-01

We describe the ultraviolet-light one-color photorefraction (UV-OPR) at 351 nm in LiNbO3 crystals with different Mg-doping concentrations and [Li]/[Nb] ratios. It is shown that as the Mg-doping concentration and/or the [Li]/[Nb] ratio increase, the refractive index change and the two-beam coupling gain increase but the response time decreases. It is also shown that the recording sensitivity as large as ∼27 cm/J is obtainable at a recording intensity of ∼1 W/cm2 in near-stoichiometric LiNbO3 doped with 2 mol% Mg. This sensitivity is approximately one order of magnitude higher than those for other LiNbO3 crystals. We also describe the ultraviolet-light-gating two-color photorefraction (UV-TPR) using 365 nm gating and 633 nm recording beams in LiNbO3 crystals with different Mg-doping concentrations and [Li]/[Nb] ratios. It is shown that UV-TPR is only observed in near-stoichiometric crystals and the grating-formation dynamics strongly depend on the Mg concentration.

Theoretical research of the spin-Hamiltonian parameters for two rhombic W5+ centers in KTiOPO4 (KTP) crystal through a two-mechanism model

NASA Astrophysics Data System (ADS)

Mei, Yang; Chen, Bo-Wei; Wei, Chen-Fu; Zheng, Wen-Chen

2016-09-01

The high-order perturbation formulas based on the two-mechanism model are employed to calculate the spin-Hamiltonian parameters (g factors gi and hyperfine structure constants Ai, where i=x, y, z) for two approximately rhombic W5+ centers in KTiOPO4 (KTP) crystal. In the model, both the widely-applied crystal-field (CF) mechanism concerning the interactions of CF excited states with the ground state and the generally-neglected charge-transfer (CT) mechanism concerning the interactions of CT excited states with the ground state are included. The calculated results agree with the experimental values, and the signs of constants Ai are suggested. The calculations indicate that (i) for the high valence state dn ions in crystals, the contributions to spin-Hamiltonian parameters should take into account both the CF and CT mechanisms and (ii) the large g-shifts |Δgi | (=|gi-ge |, where ge≈ 2.0023) for W5+ centers in crystals are due to the large spin-orbit parameter of free W5+ ion.

Numerical investigation of a scalable setup for efficient terahertz generation using a segmented tilted-pulse-front excitation.

PubMed

Pálfalvi, László; Tóth, György; Tokodi, Levente; Márton, Zsuzsanna; Fülöp, József András; Almási, Gábor; Hebling, János

2017-11-27

A hybrid-type terahertz pulse source is proposed for high energy terahertz pulse generation. It is the combination of the conventional tilted-pulse-front setup and a transmission stair-step echelon-faced nonlinear crystal with a period falling in the hundred-micrometer range. The most important advantage of the setup is the possibility of using plane parallel nonlinear optical crystal for producing good-quality, symmetric terahertz beam. Another advantage of the proposed setup is the significant reduction of imaging errors, which is important in the case of wide pump beams that are used in high energy experiments. A one dimensional model was developed for determining the terahertz generation efficiency, and it was used for quantitative comparison between the proposed new hybrid setup and previously introduced terahertz sources. With lithium niobate nonlinear material, calculations predict an approximately ten-fold increase in the efficiency of the presently described hybrid terahertz pulse source with respect to that of the earlier proposed setup, which utilizes a reflective stair-step echelon and a prism shaped nonlinear optical crystal. By using pump pulses of 50 mJ pulse energy, 500 fs pulse length and 8 mm beam spot radius, approximately 1% conversion efficiency and 0.5 mJ terahertz pulse energy can be reached with the newly proposed setup.

Devitrification studies of wollastonite-tricalcium phosphate eutectic glass.

PubMed

Magallanes-Perdomo, M; Pena, P; De Aza, P N; Carrodeguas, R G; Rodríguez, M A; Turrillas, X; De Aza, S; De Aza, A H

2009-10-01

The present paper describes and discusses the devitrification and crystallization process of wollastonite-tricalcium phosphate (W-TCP) eutectic glass. This process was studied in situ from room temperature up to 1375 degrees C, by neutron diffractometry in vacuum. The data obtained were combined and compared with those performed in ambient atmosphere by differential thermal analysis and with those of samples fired in air at selected temperatures, and then cooled down and subsequently studied by laboratory XRD and field emission scanning electron microscopy fitted with energy X-ray dispersive spectroscopy. The experimental evidence indicates that the devitrification of W-TCP eutectic glass begins at approximately 870 degrees C with the crystallization of a Ca-deficient apatite phase, followed by wollastonite-2M (CaSiO(3)) crystallization at approximately 1006 degrees C. At 1375 degrees C, the bio-glass-ceramic is composed of quasi-rounded colonies formed by a homogeneous mixture of pseudowollastonite (CaSiO(3)) and alpha-tricalcium phosphate (Ca(3)(PO(4))(2)). This microstructure corresponds to irregular eutectic structures. It was also found that it is possible to obtain from the eutectic composition of the wollastonite-tricalcium phosphate binary system a wide range of bio-glass-ceramics, with different crystalline phases present, through appropriate design of thermal treatments.

Fate of Bacterial and Viral Bio-Warfare Agents in Disinfected Waters

DTIC Science & Technology

2010-10-01

600 nm; approximately 4 h). An aliquot of 0.4 mL bacterial culture is spread onto the surface of Sporulation Media A Medium (SMA) and incubated at...dishes containing Sporulation Medium Sterile distilled water at 4 °C 70% EtOH Crystal violet Stain 1.2 Sporulation media A: Nutrient broth 8g/L...phase (approximately 4 h). 2.2 Seeding the Sporulation Plates 1. Label 150 mm Petri dishes of SM A Medium. 2. Inoculate, by aseptically spreading

Pr:YAlO(3) microchip laser.

PubMed

Fibrich, Martin; Jelínková, Helena; Sulc, Jan; Nejezchleb, Karel; Skoda, Václav

2010-08-01

A cw Pr:YAlO(3) microchip-laser operation in the near-IR spectral region is reported. A microchip resonator was formed by dielectric mirrors directly deposited on the Pr:YAlO(3) crystal surfaces. For active medium pumping, a GaN laser diode providing up to 1W of output power at approximately 448 nm was used. 139mW of laser radiation at 747nm wavelength has been extracted from the microchip-laser system. Slope efficiency related to the incident pumping power was approximately 25%.

Epstein-Barr virus and regulatory T cells in Egyptian paediatric patients with acute B lymphoblastic leukaemia.

PubMed

Ateyah, Mohamed E; Hashem, Mona E; Abdelsalam, Mohamed

2017-02-01

Acute B lymphoblastic leukaemia (B-ALL) is the most common type of childhood malignancy worldwide but little is known of its origin. Recently, many studies showed both a high incidence of Epstein-Barr virus (EBV) infection and high levels of CD4 + CD25 + Foxp3 + (Treg cells) in children with B-ALL. In our study, we investigated the possible relationship between EBV infection and the onset of B-ALL, and its relation to expression of CD4 + , CD25 high+ Foxp3+ T regulatory cells. We analysed expression and mean fluorescence intensity (MFI) of Treg cells in peripheral blood of 45 children with B-ALL and in 40 apparently healthy children as a control, using flow cytometry. Serum anti-EBV viral capsid antigen (VCA) IgG, anti-EBV nuclear antigen (EBNA) IgG (for latent infection) and anti-EBV VCA IgM (for acute infection) were investigated using ELISA. Analysis of the Treg cells population in patients and controls revealed that expression of CD4 + CD25 high+ T lymphocytes was higher in patients than in controls (mean±SD 15.7±4.1 and 10.61±2.6 in patients and controls, respectively, and MFI of Foxp3 was 30.1±7.1 and 16.7±3.7 in patients and controls, respectively (p<0.001)). There was a high incidence of latent EBV infection in patients (31%) compared with controls (10%) while the incidence of acute infection was 12% in patients and 0% in the control group. To study the role of latent EBV infection in the pathogenesis of acute B-ALL, OR was calculated (OR=4.06, coefficient index 1.2-13.6). These findings suggest a possible role for Treg cells and EBV in the pathogenesis of B-ALL. Further studies are needed on the possible mechanisms of tumour genesis related to Treg cells and EBV in children with B-ALL. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Proteomic Profiling of Exosomes Leads to the Identification of Novel Biomarkers for Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duijvesz, Diederick; Burnum-Johnson, Kristin E.; Gritsenko, Marina A.

Introduction: Current markers for prostate cancer, such as PSA lack specificity. Therefore, novel biomarkers are needed. Unfortunately, biomarker discovery from body fluids is often hampered by the high abundance of many proteins unrelated to disease. An attractive alternative biomarker discovery approach is the isolation of small vesicles (exosomes, ~100 nm). They contain proteins that are specific to the tissue from which they are derived and therefore can be considered as treasure chests for disease-specific marker discovery. Profiling prostate cancer-derived exosomes could reveal new markers for this malignancy. Materials and Methods: Exosomes were isolated from 2 immortalized primary prostate epithelial cellsmore » (PNT2C2 and RWPE-1) and 2 PCa cell lines (PC346C and VCaP) by ultracentrifugation. Proteomic analyses utilized a nanoLC coupled with an LTQ-Orbitrap operated in tandem MS (MS/MS) mode, followed by the Accurate Mass and Time (AMT) tag approach. Exosomal proteins were validated by Western blotting. A Tissue Micro Array, containing 481 different PCa samples (radical prostatectomy), was used to correlate candidate markers with several clinical-pathological parameters such as PSA, Gleason score, biochemical recurrence, and (PCa-related) death. Results: Proteomic characterization resulted in the identification of 263 proteins by at least 2 peptides. Specifically analysis of exosomes from PNT2C2, RWPE-1, PC346C, and VCaP identified 248, 233, 169, and 216 proteins, respectively. Statistical analyses revealed 52 proteins differently expressed between PCa and control cells, 9 of which were more abundant in PCa. Validation by Western blotting confirmed a higher abundance of FASN, XPO1 and PDCD6IP (ALIX) in PCa exosomes. The Tissue Micro 4 Array showed strong correlation of higher Gleason scores and local recurrence with increased cytoplasmic XPO1 (P<0.001). Conclusions: Differentially abundant proteins of cell line-derived exosomes make a clear subdivision between benign and malignant origin. Validation showed a preferential abundance of PDCD6IP, FASN and XPO1. Cytoplasmic XPO1 is the most promising candidate biomarker.« less

Measurement of Epstein-Barr virus DNA load using a novel quantification standard containing two EBV DNA targets and SYBR Green I dye.

PubMed

Lay, Meav-Lang J; Lucas, Robyn M; Ratnamohan, Mala; Taylor, Janette; Ponsonby, Anne-Louise; Dwyer, Dominic E

2010-09-22

Reactivation of Epstein-Barr virus (EBV) infection may cause serious, life-threatening complications in immunocompromised individuals. EBV DNA is often detected in EBV-associated disease states, with viral load believed to be a reflection of virus activity. Two separate real-time quantitative polymerase chain reaction (QPCR) assays using SYBR Green I dye and a single quantification standard containing two EBV genes, Epstein-Barr nuclear antigen-1 (EBNA-1) and BamHI fragment H rightward open reading frame-1 (BHRF-1), were developed to detect and measure absolute EBV DNA load in patients with various EBV-associated diseases. EBV DNA loads and viral capsid antigen (VCA) IgG antibody titres were also quantified on a population sample. EBV DNA was measurable in ethylenediaminetetraacetic acid (EDTA) whole blood, peripheral blood mononuclear cells (PBMCs), plasma and cerebrospinal fluid (CSF) samples. EBV DNA loads were detectable from 8.0 × 10(2) to 1.3 × 10(8) copies/ml in post-transplant lymphoproliferative disease (n = 5), 1.5 × 10(3) to 2.0 × 10(5) copies/ml in infectious mononucleosis (n = 7), 7.5 × 10(4) to 1.1 × 10(5) copies/ml in EBV-associated haemophagocytic syndrome (n = 1), 2.0 × 10(2) to 5.6 × 10(3) copies/ml in HIV-infected patients (n = 12), and 2.0 × 10(2) to 9.1 × 10(4) copies/ml in the population sample (n = 218). EBNA-1 and BHRF-1 DNA were detected in 11.0% and 21.6% of the population sample respectively. There was a modest correlation between VCA IgG antibody titre and BHRF-1 DNA load (rho = 0.13, p = 0.05) but not EBNA-1 DNA load (rho = 0.11, p = 0.11). Two sensitive and specific real-time PCR assays using SYBR Green I dye and a single quantification standard containing two EBV DNA targets, were developed for the detection and measurement of EBV DNA load in a variety of clinical samples. These assays have application in the investigation of EBV-related illnesses in immunocompromised individuals.

Strong viral associations with SLE among Filipinos

PubMed Central

Vista, Evan S; Weisman, Michael H; Ishimori, Mariko L; Chen, Hua; Bourn, Rebecka L; Bruner, Ben F; Hamijoyo, Laniyati; Tanangunan, Robelle D; Gal, Noga J; Robertson, Julie M; Harley, John B; Guthridge, Joel M; Navarra, Sandra V; James, Judith A

2017-01-01

Objectives Epstein-Barr virus (EBV) is considered an important environmental factor in SLE aetiology, but the relationship between SLE and EBV in the Filipino population is unknown. We tested associations between SLE, lupus-associated autoantibodies and seropositivity for EBV and other herpes viruses in the Filipino population. Methods Sera from Filipino patients with SLE (n=233), unaffected first-degree relatives (FDRs, n=543) and unrelated controls (n=221) were tested for antibodies against EBV, cytomegalovirus (CMV) and herpes simplex viruses (HSV-1 and HSV-2) by standardised ELISAs. Humoral specificity against EBV nuclear antigen (EBNA)-1 was compared by solid-phase epitope mapping. Autoantibodies were detected by a bead-based multiplex assay. Results were analysed by Fisher's exact test, Student's t-test, χ2 test and one-way analysis of variance, as appropriate for the question. Results Filipino patients with SLE had increased seroprevalence and elevated antibody concentrations against EBV viral capsid antigen (EBV-VCA), CMV, HSV-1 and HSV-2 compared with unrelated controls (p<0.05). Seropositivity for anti-EBV early antigen (EA), a marker of EBV reactivation, was dramatically increased in patients with SLE compared with unrelated controls (92.3% vs 40.4%; OR 17.15(95% CI 10.10, 30.66), p<0.0001) or unaffected FDRs (49.4%; OR 12.04(7.42, 20.74), p<0.0001), despite similar seroprevalence of EBV-VCA in patients and FDRs. In patients with SLE, EBV-EA seropositivity correlated with lupus-associated autoantibodies (p<0.001), most notably with autoantibodies against dsDNA, chromatin, Sm, SmRNP and RNP A (p<0.01). Patient and unrelated control sera reacted to the highly repetitive glycine and alanine domain of EBNA-1. An epitope spanning EBNA-1410-420 was identified in sera of patients with SLE and showed limited binding by FDR and control sera. Conclusions Filipino patients with SLE have elevated prevalence and concentrations of antibodies against EBV, CMV, HSV-1 and HSV-2 antigens, along with altered anti-EBNA-1 specificities. EBV reactivation is more common among Filipino patients with SLE compared with healthy Filipinos and may contribute to SLE pathogenesis in this population. PMID:29214036

Manipulation of photons at the surface of three-dimensional photonic crystals.

PubMed

Ishizaki, Kenji; Noda, Susumu

2009-07-16

In three-dimensional (3D) photonic crystals, refractive-index variations with a periodicity comparable to the wavelength of the light passing through the crystal give rise to so-called photonic bandgaps, which are analogous to electronic bandgaps for electrons moving in the periodic electrostatic potential of a material's crystal structure. Such 3D photonic bandgap crystals are envisioned to become fundamental building blocks for the control and manipulation of photons in optical circuits. So far, such schemes have been pursued by embedding artificial defects and light emitters inside the crystals, making use of 3D bandgap directional effects. Here we show experimentally that photons can be controlled and manipulated even at the 'surface' of 3D photonic crystals, where 3D periodicity is terminated, establishing a new and versatile route for photon manipulation. By making use of an evanescent-mode coupling technique, we demonstrate that 3D photonic crystals possess two-dimensional surface states, and we map their band structure. We show that photons can be confined and propagate through these two-dimensional surface states, and we realize their localization at arbitrary surface points by designing artificial surface-defect structures through the formation of a surface-mode gap. Surprisingly, the quality factors of the surface-defect mode are the largest reported for 3D photonic crystal nanocavities (Q up to approximately 9,000). In addition to providing a new approach for photon manipulation by photonic crystals, our findings are relevant for the generation and control of plasmon-polaritons in metals and the related surface photon physics. The absorption-free nature of the 3D photonic crystal surface may enable new sensing applications and provide routes for the realization of efficient light-matter interactions.

Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loiko, V. A., E-mail: loiko@ifanbel.bas-net.by; Konkolovich, A. V.; Zyryanov, V. Ya.

2017-03-15

We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet–polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing themore » volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ{sub s} and–θ{sub s} relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal–polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.« less

Iron inhibits hydroxyapatite crystal growth in vitro.

PubMed

Guggenbuhl, Pascal; Filmon, Robert; Mabilleau, Guillaume; Baslé, Michel F; Chappard, Daniel

2008-07-01

Hemochromatosis is a known cause of osteoporosis in which the pathophysiology of bone loss is largely unknown and the role of iron remains questionable. We have investigated the effects of iron on the growth of hydroxyapatite crystals in vitro on carboxymethylated poly(2-hydroxyethyl methacrylate) pellets. This noncellular and enzyme-independent model mimics the calcification of woven bone (composed of calcospherites made of hydroxyapatite crystals). Polymer pellets were incubated with body fluid containing iron at increasing concentrations (20, 40, 60 micromol/L). Hydroxyapatite growth was studied by chemical analysis, scanning electron microscopy, and Raman microscopy. When incubated in body fluid containing iron, significant differences were observed with control pellets. Iron was detected at a concentration of 5.41- to 7.16-fold that of controls. In pellets incubated with iron, there was a approximately 3- to 4-fold decrease of Ca and P and a approximately 1.3- to 1.4-fold increase in the Ca/P ratio. There was no significant difference among the iron groups of pellets, but a trend to a decrease of Ca with the increase of iron concentration was noted. Calcospherite diameters were significantly lower on pellets incubated with iron. Raman microspectroscopy showed a decrease in crystallinity (measured by the full width of the half height of the 960 Deltacm(-1) band) with a significant increase in carbonate substitution (measured by the intensity ratio of 1071 to 960 Deltacm(-1) band). Energy dispersive x-ray analysis identified iron in the calcospherites. In vitro, iron is capable to inhibit bone crystal growth with significant changes in crystallinity and carbonate substitution.

Micellar-shape anisometry near isotropic-liquid-crystal phase transitions

NASA Astrophysics Data System (ADS)

Itri, R.; Amaral, L. Q.

1993-04-01

Micellar phases of the sodium dodecyl (lauryl) sulfate (SLS)-water-decanol system have been studied by x-ray scattering in the isotropic (I) phase, with emphasis on the I-->hexagonal (Hα) and I-->nematic-cylindrical (Nc) lyotropic liquid-crystal phase transitions. Analysis of the scattering curves is made through modeling of the product P(q)S(q), where P(q) is the micellar form factor and S(q) is the intermicellar interference function, calculated from screened Coulombic repulsion in a mean spherical approximation. Results show that micelles grow more by decanol addition near the I-->Nc transition (anisometry ν~=3) than by increased amphiphile concentration in the binary system near the I-->Hα phase transition (ν~=2.4). These results compare well with recent theories for isotropic-liquid-crystal phase transitions.

The effect of solute on the homogeneous crystal nucleation frequency in metallic melts

NASA Technical Reports Server (NTRS)

Thompson, C. V.; Spaepen, F.

1982-01-01

A complete calculation that extends the classical theory for crystal nucleation in pure melts to binary alloys has been made. Using a regular solution model, approximate expressions have been developed for the free energy change upon crystallization as a function of solute concentration. They are used, together with model-based estimates of the interfacial tension, to calculate the nucleation frequency. The predictions of the theory for the maximum attainable undercooling are compared with existing experimental results for non-glass forming alloys. The theory is also applied to several easy glass-forming alloys (Pd-Si, Au-Si, Fe-B) for qualitative comparison with the present experimental experience on the ease of glass formation, and for assessment of the potential for formation of the glass in bulk.

Synthesis of full Poincaré beams by means of uniaxial crystals

NASA Astrophysics Data System (ADS)

Piquero, G.; Monroy, L.; Santarsiero, M.; Alonzo, M.; de Sande, J. C. G.

2018-06-01

A simple optical system is proposed to generate full-Poincaré beams (FPBs), i.e. beams presenting all possible states of (total) polarization across their transverse section. The method consists in focusing a uniformly polarized laser beam onto a uniaxial crystal having its optic axis parallel to the propagation axis of the impinging beam. A simple approximated model is used to obtain the analytical expression of the beam polarization at the output of the crystal. The output beam is then proved to be a FPB. By changing the polarization state of the input field, full-Poincaré beams are still obtained, but presenting different distributions of the polarization state across the beam section. Experimental results are reported, showing an excellent agreement with the theoretical predictions.

Order-disorder-reorder process in thermally treated dolomite samples: a combined powder and single-crystal X-ray diffraction study

NASA Astrophysics Data System (ADS)

Zucchini, A.; Comodi, P.; Katerinopoulou, A.; Balic-Zunic, T.; McCammon, C.; Frondini, F.

2012-04-01

A combined powder and single-crystal X-ray diffraction analysis of dolomite [CaMg(CO3)2] heated to 1,200°C at 3 GPa was made to study the order-disorder-reorder process. The order/disorder transition is inferred to start below 1,100°C, and complete disorder is attained at approximately 1,200°C. Twinned crystals characterized by high internal order were found in samples annealed over 1,100°C, and their fraction was found to increase with temperature. Evidences of twinning domains combined with probable remaining disordered portions of the structure imply that reordering processes occur during the quench. Twin domains are hereby proposed as a witness to thermally induced intra-layer-type cation disordering.

Hollow-core photonic-crystal fibres for laser dentistry.

PubMed

Konorov, Stanislav O; Mitrokhin, Vladimir P; Fedotov, Andrei B; Sidorov-Biryukov, Dmitrii A; Beloglazov, Valentin I; Skibina, Nina B; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M

2004-04-07

Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 microm Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 microm and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 microm laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

Fabrication and comparison of PMN-PT single crystal, PZT and PZT-based 1-3 composite ultrasonic transducers for NDE applications.

PubMed

Kim, Ki-Bok; Hsu, David K; Ahn, Bongyoung; Kim, Young-Gil; Barnard, Daniel J

2010-08-01

This paper describes fabrication and comparison of PMN-PT single crystal, PZT, and PZT-based 1-3 composite ultrasonic transducers for NDE applications. As a front matching layer between test material (Austenite stainless steel, SUS316) and piezoelectric materials, alumina ceramics was selected. The appropriate acoustic impedance of the backing materials for each transducer was determined based on the results of KLM model simulation. Prototype ultrasonic transducers with the center frequencies of approximately 2.25 and 5MHz for contact measurement were fabricated and compared to each other. The PMN-PT single crystal ultrasonic transducer shows considerably improved performance in sensitivity over the PZT and PZT-based 1-3 composite ultrasonic transducers. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Acoustic anisotropy of acoustooptic TI(3)AsS(4) crystals.

PubMed

Martynyuk-Lototska, Iryna; Kushnirevych, Marian; Zapeka, Bohdan; Krupych, Oleh; Kokhan, Oleksandr; Pogodin, Artem; Peresh, Eugen; Mys, Oksana; Vlokh, Rostyslav

2015-02-20

We present comprehensive experimental measurements and analysis of anisotropy of the acoustic wave velocities for TI(3)AsS(4) crystals, including the obliquity and nonorthogonality of the acoustic waves, and the deviations from purely longitudinal and transverse polarization types. We have found that the crystals under analysis are characterized by rather low transverse wave velocities v(23) and v(32), which are both equal to 630 m/s. It is shown that the efficiency of acoustooptic (AO) interactions in TI(3)AsS(4) can be notably increased when providing anisotropic interaction with the slowest transverse acoustic wave. Under the previously mentioned conditions, the AO figure-of-merit can be estimated to be extremely high, i.e., approximately 3×10(-12) s(3)/kg.

Monopropellant thruster exhaust plume contamination measurements

NASA Technical Reports Server (NTRS)

Baerwald, R. K.; Passamaneck, R. S.

1977-01-01

The potential spacecraft contaminants in the exhaust plume of a 0.89N monopropellant hydrazine thruster were measured in an ultrahigh quartz crystal microbalances located at angles of approximately 0 deg, + 15 deg and + or - 30 deg with respect to the nozzle centerline. The crystal temperatures were controlled such that the mass adhering to the crystal surface at temperatures of from 106 K to 256 K could be measured. Thruster duty cycles of 25 ms on/5 seconds off, 100 ms on/10 seconds off, and 200 ms on/20 seconds off were investigated. The change in contaminant production with thruster life was assessed by subjecting the thruster to a 100,000 pulse aging sequence and comparing the before and after contaminant deposition rates. The results of these tests are summarized, conclusions drawn, and recommendations given.

Gene silencing pathway RNA-dependent RNA polymerase of Neurospora crassa: yeast expression and crystallization of selenomethionated QDE-1 protein.

PubMed

Laurila, Minni R L; Salgado, Paula S; Makeyev, Eugene V; Nettelship, Joanne; Stuart, David I; Grimes, Jonathan M; Bamford, Dennis H

2005-01-01

The RNA-dependent RNA polymerase, QDE-1, is a component of the RNA silencing pathway in Neurospora crassa. The enzymatically active carboxy-terminal fragment QDE-1 DeltaN has been expressed in Saccharomyces cerevisiae in the presence and absence of selenomethionine (SeMet). The level of SeMet incorporation was estimated by mass spectrometry to be approximately 98%. Both native and SeMet proteins were crystallized in space group P2(1) with unit cell parameters a=101.2, b=122.5, c=114.4A, beta=108.9 degrees , and 2 molecules per asymmetric unit. The native and SeMet crystals diffract to 2.3 and 3.2A, respectively, the latter are suitable for MAD structure determination.

The effects of Raman scattering accompanied by the soliton excitation occurring in molecular crystals

NASA Astrophysics Data System (ADS)

Pang, X. F.

2001-06-01

A theoretical research is made for the effects of Raman scattering caused by the soliton excitation occurring in the organic molecular crystals, e.g., acetanilide, on the basis of vibration model of amide-I. The energy gap between the soliton state and the vibron state have been found by partial diagonalized method in second quantized representation, which is 18.1-33 cm -1. This result is approximately consistent with the red shift value obtained from the experiments, 16 cm -1. The differential cross-section of the Raman scattering, arising from the soliton excitation, has also been obtained. Finally, we derive some properties of the Raman scattering in such a case. This result establishes spectral signatures of the soliton in the molecular crystals, which may be observed in the experiment.

Phase-Shifting Liquid Crystal Interferometers for Microgravity Fluid Physics

NASA Technical Reports Server (NTRS)

Griffin, DeVon W.; Marshall, Keneth L.

2002-01-01

The initial focus of this project was to eliminate both of these problems in the Liquid Crystal Point-Diffraction Interferometer (LCPDI). Progress toward that goal will be described, along with the demonstration of a phase shifting Liquid Crystal Shearing Interferometer (LCSI) that was developed as part of this work. The latest LCPDI, other than a lens to focus the light from a test section onto a diffracting microsphere within the interferometer and a collimated laser for illumination, the pink region contained within the glass plates on the rod-mounted platform is the complete interferometer. The total width is approximately 1.5 inches with 0.25 inches on each side for bonding the electrical leads. It is 1 inch high and there are only four diffracting microspheres within the interferometer. As a result, it is very easy to align, achieving the first goal. The liquid crystal electro-optical response time is a function of layer thickness, with thinner devices switching faster due to a reduction in long-range viscoelastic forces between the LC molecules. The LCPDI has a liquid crystal layer thickness of 10 microns, which is controlled by plastic or glass microspheres embedded in epoxy 'pads' at the corners of the device. The diffracting spheres are composed of polystyrene/divinyl benzene polymer with an initial diameter of 15 microns. The spheres deform slightly when the interferometer is assembled to conform to the spacing produced by the microsphere-filled epoxy spacer pads. While the speed of this interferometer has not yet been tested, previous LCPDIs fabricated at the Laboratory for Laser Energetics switched at a rate of approximately 3.3 Hz, a factor of 10 slower than desired. We anticipate better performance when the speed of these interferometers is tested since they are approximately three times thinner. Phase shifting in these devices is a function of the AC voltage level applied to the liquid crystal. As the voltage increases, the dye in the liquid crystal tends to become more transparent, thus introducing a rather large amount of error into the phase-shifting measurement. While that error can be greatly reduced by normalization, we prefer eliminating the source of the error. To that end, we have pursued development of a 'blend' of custom dyes that will not exhibit these properties. That goal has not yet been fully achieved. Guardalben, et al, presented a similar set of interferograms in a paper partially funded by this grant. Shearing interferometers are a second class of common path interferometers. Typically they consist of a thick glass plate optimized for equal reflection from the front and back surface. While not part of the original thrust of the project, through the course of laboratory work, we demonstrated a prototype of a shearing interferometer capable of phase shifting using a commercial liquid crystal retardation plate. A schematic of this liquid crystal shearing interferometer (LCSI) and a sample set of interferograms are in the reference. This work was also supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article. Additional information is included in the original extended abstract.

X-Ray diffraction and mu-Raman investigation of the monoclinic-orthorhombic phase transition in Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solutions.

PubMed

Clavier, Nicolas; Hingant, Nina; Rivenet, Murielle; Obbade, Saïd; Dacheux, Nicolas; Barré, Nicole; Abraham, Francis

2010-02-15

A complete Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x = 0, 0.5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a approximately 10.5 A, b approximately 8.5 A, and c approximately 9.6 A. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bicapped square antiprism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature mu-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the nu(s)(C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample.

Scattering of charge and spin excitations and equilibration of a one-dimensional Wigner crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matveev, K. A.; Andreev, A. V.; Klironomos, A. D.

2014-07-01

We study scattering of charge and spin excitations in a system of interacting electrons in one dimension. At low densities, electrons form a one-dimensional Wigner crystal. To a first approximation, the charge excitations are the phonons in the Wigner crystal, and the spin excitations are described by the Heisenberg model with nearest-neighbor exchange coupling. This model is integrable and thus incapable of describing some important phenomena, such as scattering of excitations off each other and the resulting equilibration of the system. We obtain the leading corrections to this model, including charge-spin coupling and the next-nearest-neighbor exchange in the spin subsystem.more » We apply the results to the problem of equilibration of the one-dimensional Wigner crystal and find that the leading contribution to the equilibration rate arises from scattering of spin excitations off each other. We discuss the implications of our results for the conductance of quantum wires at low electron densities« less

The 1983 hydraulic jump in Crystal Rapid: implications for river- running and geomorphic evolution in the Grand Canyon.

USGS Publications Warehouse

Kieffer, S.W.

1985-01-01

At Crystal Creek, a debris fan was emplaced in 1966, constricting the channel of the Colorado River to about 0.25 of its upstream width between 1967 and 1983, forming a major rapid. The hydraulics of Crystal Creek rapid are described, and an analysis is presented to support the hypothesis that the major wave in the rapid was a normal wave (one type of hydraulic jump). Hydraulic jumps rarely occur in natural river channels with erodible beds, but one was present at Crystal Rapid because of the unusually severe constriction of the Colorado River by the 1966 debris fan. A quantitative model for river debris fan shapes is proposed and is used to estimate prehistoric flood levels from the observed constrictions: the 0.5 value of river constriction found at the more mature debris fans in the Grand Canyon suggests that peak flood discharges of approximately 11 320 m3/s have occurred. -from Author

Numerical simulations of crystal growth in a transdermal drug delivery system

NASA Astrophysics Data System (ADS)

Zeng, Jianming; Jacob, Karl I.; Tikare, Veena

2004-02-01

Grain growth by precipitation and Ostwald ripening in an unstressed matrix of a dissolved crystallizable component was simulated using a kinetic Monte Carlo model. This model was used previously to study Ostwald ripening in the high crystallizable component regime and was shown to correctly simulate solution, diffusion and precipitation. In this study, the same model with modifications was applied to the low crystallizable regime of interest to the transdermal drug delivery system (TDS) community. We demonstrate the model's utility by simulating precipitation and grain growth during isothermal storage at different supersaturation conditions. The simulation results provide a first approximation for the crystallization occurring in TDS. It has been reported that for relatively higher temperature growth of drug crystals in TDS occurs only in the middle third of the polymer layer. The results from the simulations support these findings that crystal growth is limited to the middle third of the region, where the availability of crystallizable components is the highest, for cluster growth at relatively high temperature.

Domain characterization of Pb(Zn1/3Nb2/3)O3-(6%-7%)PbTiO3 single crystals using scanning electron acoustic microscopy

NASA Astrophysics Data System (ADS)

Wong, Meng Fei; Heng, Xiangxin; Zeng, Kaiyang

2008-10-01

Domain structures of [001]T and [011]T-cut Pb(Zn1/3Nb2/3)O3-(6%-7%)PbTiO3 (PZN-PT) single crystals are studied using scanning electron acoustic microscope (SEAM) technique. The observation of the orientation of domain walls agree reasonably well with the trigonometric projection of rhombohedral and orthorhombic dipoles on the (001) and (011) surfaces, respectively. After mechanical loading with microindentation, domain switching is also observed to form a hyperbolic butterfly shape and extend preferentially along four diagonal directions, i.e., ⟨110⟩ on (001) surface and ⟨111¯⟩ on (011) surface. The critical shear stress to cause domain switching for PZN-PT crystal is estimated to be approximately 49 MPa for both {110} and {111¯} planes based on theoretical analysis. Generally, the SEAM technique has been successfully demonstrated to be a valid technique for observation of domain structures in single crystal PZN-PTs.

Crystal Growth and Scintillation Properties of Ho-Doped Lu3Al5O12 Single Crystals

NASA Astrophysics Data System (ADS)

Sugiyama, Makoto; Yanagida, Takayuki; Fujimoto, Yutaka; Totsuka, Daisuke; Yokota, Yuui; Kurosawa, Shunsuke; Futami, Yoshisuke; Yoshikawa, Akira

2012-10-01

The crystals of 0.1, 0.5, 1, and 3% Ho doped Lu3Al5O12 (Ho:LuAG) grown by the micro-pulling-down method were examined for their scintillation properties. At wavelengths longer than 300 nm, Ho:LuAG crystals demonstrated around 60% transparency with many absorption peaks attributed to Ho3+ 4f10-4 f10 transitions. When excited by 241Am α-ray to obtain radio luminescence spectra, broad host emission and four sharp Ho3+ 4f10-4 f10 emission peaks were detected in the visible region. Light yields and decay time profiles of the samples irradiated by 137Cs γ-ray were measured using photomultiplier tubes R7600 (Hamamatsu). Ho 0.5%:LuAG showed the highest light yield of 3100 ±310 photons/MeV among the present samples. The decay time profiles were well reproduced by two components exponential approximation consisting of 0.5-1 μs and 3-6 μs.

A protein coated piezoelectric crystal detector

NASA Astrophysics Data System (ADS)

Suleiman, Ahmad; Pender, Marie; Ngeh-Ngwainbi, Jerome; Lubrano, Glenn; Guilbault, George

1990-05-01

The purpose of this project was to develop a protein coated, portable piezoelectric crystal detector for organophosphorus compounds. The performance of acetylcholinesterase, GD-1 anti-soman, anti-DMMP antibody, and bovine serum albumin (BSA) coatings was evaluated. Different immobilization methods were also tested. The responses obtained with the protein coatings immobilized via cross-linking with glutaraldehyde were acceptable, provided that the reference crystal was coated with dextran. The proposed coatings showed good stability and reasonable lifetimes that ranged from approximately three weeks in the case of the antibody coatings to several months in the case of BSA. Although moisture, gasoline, and sulfur are potential interferents, their effects on the sensor were eliminated by using a sodium sulfate scrubber which did not affect the performance of the detector towards organophosphates. A small, battery operated portable instrument capable of real time measurements with alarm function was produced. The instrument can be used in a wide range of applications, depending on the coatings applied to the crystals.

Crystallography of ordered colloids using optical microscopy. 2. Divergent-beam technique.

PubMed

Rogers, Richard B; Lagerlöf, K Peter D

2008-04-10

A technique has been developed to extract quantitative crystallographic data from randomly oriented colloidal crystals using a divergent-beam approach. This technique was tested on a series of diverse experimental images of colloidal crystals formed from monodisperse suspensions of sterically stabilized poly-(methyl methacrylate) spheres suspended in organic index-matching solvents. Complete sets of reciprocal lattice basis vectors were extracted in all but one case. When data extraction was successful, results appeared to be accurate to about 1% for lattice parameters and to within approximately 2 degrees for orientation. This approach is easier to implement than a previously developed parallel-beam approach with the drawback that the divergent-beam approach is not as robust in certain situations with random hexagonal close-packed crystals. The two techniques are therefore complimentary to each other, and between them it should be possible to extract quantitative crystallographic data with a conventional optical microscope from any closely index-matched colloidal crystal whose lattice parameters are compatible with visible wavelengths.