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Disparities in treatment and outcomes disproportionately affect minority ethnic and racial populations in many surgical fields. Although substantial research in racial disparities has focused on outcomes, little is known about how surgeon recommendations can be influenced by patient race. The aim of this study was to investigate racial and socioeconomic disparities in the surgical management of primary brain tumors.In this registry-based cohort study, we used data from the Surveillance, Epidemiology, and End Results (SEER) database (1975-2016) and the American College of Surgeons National Cancer Database (NCDB) in the USA for independent analysis. Adults (aged ≥20 years) with a new diagnosis of meningioma, glioblastoma, pituitary adenoma, vestibular schwannoma, astrocytoma, and oligodendroglioma, with information on tumour size and surgical recommendation were included in the analysis. The primary outcome of this study was the odds of a surgeon recommending against surgical resection at diagnosis of primary brain neoplasms. This outcome was determined using multivariable logistic regression with clinical, demographic, and socioeconomic factors.This study included US national data from the SEER (1975-2016) and NCDB (2004-17) databases of adults with a new diagnosis of meningioma (SEER n=63 674; NCDB n=222 673), glioblastoma (n=35 258; n=104 047), pituitary adenoma (n=27 506; n=87 772), vestibular schwannoma (n=11 525; n=30 745), astrocytoma (n=5402; n=10 631), and oligodendroglioma (n=3977; n=9187). Independent of clinical and demographic factors, including insurance status and rural-urban continuum code, Black patients had significantly higher odds of recommendation against surgical resection of meningioma (adjusted odds ratio 1·13, 95% CI 1·06-1·21, p0·0001), glioblastoma (1·14, 1·01-1·28, p=0·038), pituitary adenoma (1·13, 1·05-1·22, p0·0001), and vestibular schwannoma (1·48, 1·19-1·84, p0·0001) when compared with White patients in the SEER dataset. Additionally, patients of unknown race had significantly higher odds of recommendation against surgical resection for pituitary adenoma (1·80, 1·41-2·30, p0·0001) and vestibular schwannoma (1·49, 1·10-2·04, p=0·011). Performing a validation analysis using the NCDB dataset confirmed these significant results for Black patients with meningioma (1·18, 1·14-1·22, p0·0001), glioblastoma (1·19, 1·12-1·28, p0·0001), pituitary adenoma (1·21, 1·16-1·25, p0·0001), and vestibular schwannoma (1·19, 1·04-1·35, p=0·0085), and indicated and indicated that the findings are independent of patient comorbidities. When further restricted to the most recent decade in SEER, these inequities held true for Black patients, except those with glioblastoma (meningioma [1·18, 1·08-1·28, p0·0001], pituitary adenoma [1·20, 1·09-1·31, p0·0001], and vestibular schwannoma [1·54, 1·16-2·04, p=0·0031]).Racial disparities in surgery recommendations in the USA exist for patients with primary brain tumours, independent of potential confounders including clinical, demographic, and select socioeconomic factors. Further studies are needed to understand drivers of this bias and enhance equality in surgical care.None.

Tympanojugular paragangliomas (TJPs) are slow-growing tumors arising within the middle ear or jugular foramen. The development of modified skull base approaches and the increasing use of stereotactic radiosurgery have provided more modern techniques in the management of TJPs. Several factors dictating approach selection, and resulting clinical outcomes have been inconsistently described.A systematic review of the literature describing modern management of complex TJPs was performed and summarized. A random-effects meta-analysis was performed to describe the rate of tumor control, complications, and symptom improvement in patients undergoing radiosurgery or surgical resection.Nineteen studies were identified with a total of 852 TJP patients. A minority (153 patients) underwent radiosurgery while 699 underwent surgery. On meta-analysis, there was a 3.5% (95% confidence interval [CI]: 0.5%-6.4%) tumor growth rate following radiosurgery and 3.9% (95% confidence interval [CI]: 1.8%-6.0%) recurrence rate in surgical resection, with no significant moderator effect between the 2 groups (P = 0.9046). Complication rate for radiosurgery was 7.6% (95% CI: 2.8%-12.4%), differing significantly from surgical complication rates of 29.6% (95% CI: 17.1-42.0%, P = 0.0418).Stereotactic radiosurgery and surgical resection for TJPs have similar rates of tumor recurrence. Radiation is associated with less risk and lower morbidity, yet there is comparably modest reduction of the tumor size. In sum, the data suggest that radiosurgery is a reasonable management option for patients with minimal symptoms who are high risk for surgery. Microsurgical resection should be reserved for patients with lower cranial neuropathies or those who have failed radiation treatment.

Background Balloon test occlusion is a widely used method for predicting tolerance of vessel occlusion in the treatment of aneurysms, fistulae, and head and neck neoplasms. However, the false-negative rate is variably reported due in part to the diversity of perfusion monitoring methods. Objective To evaluate the rate of symptomatic ischemic events after a negative balloon test occlusion and determine whether perfusion monitoring methods contribute to differences in these rates. Methods PubMed was systematically searched for studies between 1990 and 2020 that reported rates of ischemic outcomes of parental vessel occlusion in patients who passed balloon test occlusion. A generalized linear mixed model meta-analysis was performed. Results were expressed as the rate of symptomatic ischemic events after parental vessel occlusion without vessel bypass in patients who passed balloon test occlusion. Results Thirty-two studies met the inclusion criteria. The overall pooled rate of ischemic events after passing balloon test occlusion was 3.7% (95% confidence interval [CI]: 1.7–7.8). This rate was 3.8% (95% CI: 1.1–12.8) when monitored with angiography, 2.2% (95% CI: 0.4–10.2) when monitored by a form of computed tomography, and 5.3% (95% CI: 1.2–20.4) when monitored by 2 or more methods of perfusion assessment. The complication rate of balloon test occlusion was 0.8% (95% CI: 0.2–2.7). Conclusions Balloon test occlusion results in a low rate of subsequent ischemic events, without conclusive evidence of variation between methods of perfusion assessment. The choice of method should focus on reduction of complication risk, experience of the interventional team, and avoidance of prolonged test occlusion times.

Background Pituitary apoplexy after resection of giant pituitary adenomas is a rare but often cited morbidity associated with devastating outcomes. It presents as hemorrhage and/or infarction of residual tumor in the postoperative period. Because of its rarity, its incidence and consequences remain ill defined. Objective The aim of this study is to estimate the rate of postoperative pituitary apoplexy after resection of giant pituitary adenomas and assess the morbidity and mortality associated with apoplexy. Methods A systematic review of literature was performed to examine extent of resection in giant pituitary adenomas based on surgical approach, rate of postoperative apoplexy, morbidities, and mortality. Advantages and disadvantages of each approach were compared. Results Seventeen studies were included in quantitative analysis describing 1,031 cases of resection of giant pituitary adenomas. The overall rate of subtotal resection ( Conclusion Postoperative pituitary apoplexy is uncommon but is associated with high rates of morbidity and mortality in subtotal resection cases. These findings highlight the importance in achieving a maximal resection in a time sensitive fashion to mitigate the severe consequences of postoperative apoplexy.

Background Antibody-drug conjugates (ADC) increase the efficacy of current chemotherapeutics, decrease off site toxicity, and pair drug function with immunomodulatory effects. Current ADC platforms depend on the use of covalent linker molecules between the antibody and the drug of choice. This approach leads to significant variation in the number of drug molecules bound, the location of their binding, and inconsistency in maintaining the structure and antigen affinity of the antibody. Because of this, covalent-based ADC development requires extensive separation steps to isolate the ideal isotypes of the ADC. This testing and separation must be repeated for each antibody and each drug considered. Here we present a peptide that non-covalently binds multiple clinically relevant IgG1 antibodies at a controlled ratio and location, then demonstrate its use as a modular ADC linker platform. Methods Peptide-antibody and antibody-antigen affinity were determined using Biacore surface plasmon resonance. Peptides conjugated with alexafluor or DM1 were purified using HPLC and structure was confirmed through mass spectrometry. Flow cytometry verified delivery of peptide-atezolizumab conjugates to C1861 PDL1+ melanoma cells. Peptide-DM1 potency was determined in-vitro using a calcein-AM and propridium iodine live/dead cell double staining. Results Antibody-Binding Peptide Linker (APL) was developed from a series of space filling amino acid substitutions at key residues on an 18-mer peptide derived from a hydrophobic pocket on human albumin (figure 1a). A lysine containing tail was added to the C-terminus for conjugation to small molecule therapeutics through amine coupling. APL has nanomolar binding affinity for the fab region of IgG1 antibodies including rituximab (KD= 1.85 × 10-8), bevacizumab (KD= 5.2 × 10-8), trastuzumab (KD= 8.87 × 10-8), and atezolizumab (KD= 3.78 × 10-8) (figure 1b). Kinetic binding models, performed by Biacore surface plasmon resonance, showed a 2:1 association of peptide to antibody. All four antibodies retained their antigen affinity when bound by APL (figure 2a). Labeling of APL with an alexafluor showed delivery to PDL1+ melanoma cells when given bound to the anti-PDL1 antibody atezolizumab (figure 2b). Conjugation of APL with the tubulin inhibitor DM1 (figure 2c) resulted in a drug conjugated peptide that retained the potency of the drug itself (figure 2d). Conclusions Antibody-Binding Peptide Linker (APL) non-covalently binds clinical IgG1 antibodies at a fixed two to one ratio without affecting antigen affinity. Conjugation of APL with a drug of choice provides a modular Antibody-Drug Conjugate platform where both the antibody and drug can be substituted with ease.

Background Total pancreatectomy with islet autotransplantation is a therapeutic surgical option for patients with chronic pancreatitis leading to significant reduction in pain, improvement in quality of life, and potential for preservation of partial to full endocrine function. Data on the factors associated with short-term morbidities are limited. Methods We queried the American College of Surgeons National Surgery Quality Improvement Project for patients undergoing total pancreatectomy with islet autotransplantation from 2005 to 2015. We determined 30-day morbidity and mortality and performed univariate and multivariate analysis to determine the preoperative and intraoperative factors associated with development of postoperative infectious complications. Results The rate of 30-day postoperative morbidity in 384 patients undergoing total pancreatectomy with islet autotransplantation was 36% with an overall mortality of 1%. Postoperative infectious complications developed in 29% of patients and were associated with increased operative time (P = .016),and higher postoperative wound class (P = .045). After risk adjustment, only increased operative time was independently associated with increased rates of infectious complications (OR=1.1, 95% CI = 1.01-1.13, P = .02). Conclusions Total operative time is independently associated with increased postoperative infectious complications in total pancreatectomy with islet autotransplantation. Future interventions aimed at optimizing islet isolation, surgical approach, and refinement of patient selection criteria present opportunities for reducing operative time and potentially reducing the morbidity of this surgical procedure.

In patients with metastatic melanoma, high blood levels of galectin-9 are correlated with worse overall survival and a bias towards a Th2 inflammatory state supportive of tumor growth. Although galectin-9 signaling through TIM3 on T cells has been described, less is known about the interaction of galectin-9 with macrophages. We aimed to determine whether galectin-9 is a binding partner of CD206 on macrophages and whether the result of this interaction is tumor-supportive. It was determined that incubation of CD68+ macrophages with galectin-9 or anti-CD206 blocked target binding and that both CD206 and galectin-9 were detected by immunoprecipitation of cell lysates. CD206 and galectin-9 had a binding affinity of 2.8 × 10-7 m. Galectin-9 causes CD206+ macrophages to make significantly more FGF2 and monocyte chemoattractant protein (MCP-1), but less macrophage-derived chemokine (MDC). Galectin-9 had no effect on classical monocyte subsets, but caused expansion of the non-classical populations. Lastly, there was a positive correlation between increasing numbers of CD206 macrophages and galectin-9 expression in tumors, and high levels of CD206 macrophages correlated negatively with melanoma survival. These results indicate that galectin-9 binds to CD206 on M2 macrophages, which appear to drive angiogenesis and the production of chemokines that support tumor growth and poor patient prognoses. Targeting this interaction systemically through circulating monocytes may therefore be a novel way to improve local anti-tumor effects by macrophages. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Triple-negative breast cancer (TNBC) has a faster rate of metastasis compared to other breast cancer subtypes, and no effective targeted therapies are currently FDA-approved. Recent data indicate that the androgen receptor (AR) promotes tumor survival and may serve as a potential therapeutic target in TNBC. Studies of AR in disease progression and the systemic effects of anti-androgens have been hindered by the lack of an AR-positive (AR+) immunocompetent preclinical model. In this study, we identified the transgenic MMTV-PyMT (mouse mammary tumor virus-polyoma middle tumor-antigen) mouse mammary gland carcinoma model of breast cancer and Met-1 cells derived from this model as tools to study the role of AR in breast cancer progression. AR protein expression was examined in late-stage primary tumors and lung metastases from MMTV-PyMT mice as well as in Met-1 cells by immunohistochemistry (IHC). Sensitivity of Met-1 cells to the AR agonist dihydrotestosterone (DHT) and anti-androgen therapy was examined using cell viability, migration/invasion, and anchorage-independent growth assays. Late-stage primary tumors and lung metastases from MMTV-PyMT mice and Met-1 cells expressed abundant nuclear AR protein, while negative for estrogen and progesterone receptors. Met-1 sensitivity to DHT and AR antagonists demonstrated a reliance on AR for survival, and AR antagonists inhibited invasion and anchorage-independent growth. These data suggest that the MMTV-PyMT model and Met-1 cells may serve as valuable tools for mechanistic studies of the role of AR in disease progression and how anti-androgens affect the tumor microenvironment.

Androgen receptor (AR) is expressed in 90% of estrogen receptor alpha–positive (ER+) breast tumors, but its role in tumor growth and progression remains controversial. Use of two anti-androgens that inhibit AR nuclear localization, enzalutamide and MJC13, revealed that AR is required for maximum ER genomic binding. Here, a novel global examination of AR chromatin binding found that estradiol induced AR binding at unique sites compared with dihydrotestosterone (DHT). Estradiol-induced AR-binding sites were enriched for estrogen response elements and had significant overlap with ER-binding sites. Furthermore, AR inhibition reduced baseline and estradiol-mediated proliferation in multiple ER+/AR+ breast cancer cell lines, and synergized with tamoxifen and fulvestrant. In vivo, enzalutamide significantly reduced viability of tamoxifen-resistant MCF7 xenograft tumors and an ER+/AR+ patient-derived model. Enzalutamide also reduced metastatic burden following cardiac injection. Finally, in a comparison of ER+/AR+ primary tumors versus patient-matched local recurrences or distant metastases, AR expression was often maintained even when ER was reduced or absent. These data provide preclinical evidence that anti-androgens that inhibit AR nuclear localization affect both AR and ER, and are effective in combination with current breast cancer therapies. In addition, single-agent efficacy may be possible in tumors resistant to traditional endocrine therapy, as clinical specimens of recurrent disease demonstrate AR expression in tumors with absent or refractory ER. Implications: This study suggests that AR plays a previously unrecognized role in supporting E2-mediated ER activity in ER+/AR+ breast cancer cells, and that enzalutamide may be an effective therapeutic in ER+/AR+ breast cancers. Mol Cancer Res; 14(11); 1054–67. ©2016 AACR.

Antibody directed chemotherapy (ADC) takes advantage of the selectivity of the monoclonal antibody to increase the efficacy of the chemotherapeutic agent, while reducing toxicity. Previously we described three nab-paclitaxel (Abraxane) nanoparticles coated with commercial monoclonal antibodies. Identifying the binding sites responsible for these particles could allow reverse engineering of nab-paclitaxel binding antibodies, creating a modular platform for antibody directed chemotherapeutic nanoparticles. Herein, Biacore surface plasmon resonance is used to identify an antibody binding site, HSA Peptide 40, on human serum albumin with nanomolar affinity for all three monoclonal antibodies. This 18-mer peptide, which lies in Subdomain IIIA of human serum albumin, blocks binding of all three antibodies to nab-paclitaxel when added in excess. We furthermore show the complementary binding region on all three monoclonal antibodies to be the CDR H3 loop of the Fab region, and show that they all have nano to micromolar affinity for HSA Peptide 40 and nab-paclitaxel nanoparticles. The presented data identify the nature of the critical protein-protein interaction that enables antibody coating of nab-paclitaxel.

We developed a nano-antibody targeted chemotherapy (nATC) delivery strategy in which tumor specific and clinically relevant antibodies (rituximab, anti-CD20) are non-covalently bound to the albumin scaffold of nab-paclitaxel (ABX). We define the nanoparticle formed when the 2 drugs are bound (AR160). The newly created nATC retains the cytotoxicity of ABX and CD20 affinity of rituximab in vitro. We describe the binding characteristics of the ABX and rituximab in AR160 using peptide mapping/Biacore approach. Flow-based methods, including ImageStream and nanoparticle tracking, were used to characterize the AR160 particles in vitro. A mouse model of human B-cell lymphoma was utilized to test in vivo efficacy of AR160 therapy, which suggested improved tumor targeting (biodistribution) as the most likely mechanism of AR160 therapeutic superiority over ABX or rituximab alone. These data suggest a novel platform for nATC delivery using a slight modification of existing cancer drugs with significantly improved treatment efficacy.

This economic evaluation takes the perspective of a health plan provider. The primary objective was to determine if medical expenses of members enrolled in the not-for-profit, US-based Union Pacific Railroad Employes Health Systems (UPREHS) health plan were reduced after implementing a low-cost, patient-focused education campaign on sleep-disordered breathing (SDB). The authors reviewed medical claims records of all members (N=22,275) from 2 years before (2005-2006) and 2 years after (2007-2008) the campaign. Members were assigned to a non-SDB (did not seek diagnosis or not diagnosed with SDB), an SDB-NT (diagnosed with SDB but not on therapy), or an SDB-PAP (diagnosed with SDB and on positive airway pressure [PAP] therapy) group. The authors assessed overall medical and inpatient hospital costs (calculated as annual per member per month [PMPM] costs), and number of hospital admissions. The percentage of members with SDB was 11.1% (2350/21,185) in 2005 and 10.5% (2385/22,639) in 2008. During the study, the percentage of members with SDB receiving PAP increased 145% (2005: 23%, 517/2350; 2008: 54.3%, 1265/2385). After the campaign was initiated, overall medical PMPM costs were significantly lower for the SDB-PAP than the SDB-NT group (2007: $572.10 vs. $720.27, P=0.0006; 2008: $645.66 vs. $846.58, P=0.0009), resulting in a differential cost savings of $4.9 million for the study period. In addition, inpatient hospital PMPM costs and the number of hospital admissions also were lower for the SDB-PAP group than for the SDB-NT group. These findings suggest that an SDB education campaign can improve health care outcomes and reduce medical expenses.

We developed a nano-antibody targeted chemotherapy (nATC) delivery strategy in which tumor specific and clinically relevant antibodies (rituximab, anti-CD20) are non-covalently bound to the albumin scaffold of nab-paclitaxel (ABX). We define the nanoparticle formed when the 2 drugs are bound (AR160). The newly created nATC retains the cytotoxicity of ABX and CD20 affinity of rituximab in vitro. We describe the binding characteristics of the ABX and rituximab in AR160 using peptide mapping/Biacore approach. Flow-based methods, including ImageStream and nanoparticle tracking, were used to characterize the AR160 particles in vitro. A mouse model of human B-cell lymphoma was utilized to test in vivo efficacy of AR160 therapy, which suggested improved tumor targeting (biodistribution) as the most likely mechanism of AR160 therapeutic superiority over ABX or rituximab alone. These data suggest a novel platform for nATC delivery using a slight modification of existing cancer drugs with significantly improved treatment efficacy.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype for which there are no approved targeted therapies. Preclinical and early clinical trials indicate that up to 50% of TNBC express androgen receptor (AR) and are potentially responsive to anti-androgens. However, the function of AR in TNBC and the mechanisms by which AR-targeted therapy reduces tumor burden are largely unknown. We hypothesized that AR maintains a cancer stem cell (CSC)-like tumor initiating population and serves as an anti-apoptotic factor that facilitates anchorage independence and metastasis. Anchorage-independent growth was assessed in TNBC cells cultured in forced suspension and apoptosis was measured with cleaved-caspase 3 antibody. CSC-like populations were assessed in vitro using ultra low attachment plates, CD44/CD24 staining, the ALDEFLUOR assay, and single cell mammosphere formation efficiency (MFE) assays. Tumor-initiating capacity was assessed in vivo using a limiting dilution assay. Lastly, the ability of a combination of enzalutamide (Enza) and paclitaxel to inhibit TNBC tumor growth was assessed in vivo. AR increased in TNBC cells in forced suspension culture compared to attached conditions. Cells that expressed AR resisted detachment-induced apoptosis. The CSC-like population increased in suspension culture and decreased following AR inhibition. Pre-treatment with Enza decreased the tumor-initiating capacity of TNBC cells. Enza decreased tumor volume and viability when administered simultaneously or subsequent to chemotherapy, but simultaneous treatment more effectively suppressed tumor recurrence. AR-targeted therapies may enhance the efficacy of chemotherapy even in TNBC with low AR expression by targeting a CSC-like cell population with anchorage independent, invasive potential.

Profiling of RNA from mouse mammary epithelial cells (MECs) isolated on pregnancy day 14 (P14) and lactation day 2 (L2) revealed that the majority of differentially expressed microRNA declined precipitously between late pregnancy and lactation. The decline in miR-150, which exhibited the greatest fold decrease, was verified quantitatively and qualitatively. To test the hypothesis that the decline in miR-150 is critical for lactation, MEC-specific constitutive miR-150 was achieved by crossing ROSA26-lox-STOP-lox-miR-150 mice with WAP-driven Cre recombinase mice. Both biological and foster pups nursed by bitransgenic dams exhibited a dramatic decrease in survival compared to offspring nursed by littermate control dams. Protein products of predicted miR-150 targets Fasn, Olah, Acaca, and Stat5B were significantly suppressed in MECs of bitransgenic mice with constitutive miR-150 expression as compared to control mice at L2. Lipid profiling revealed significant reduction in fatty acids synthesized by the de novo pathway in L2 MECs of bitransgenic versus control mice. Collectively, these data support the hypothesis that a synchronized decrease in miRNAs, such as miR-150, at late pregnancy serves to allow translation of targets critical for lactation.

Double polarization photoelectron spectroscopy using circularly polarized x-rays and true spin detection has been performed using the 2p core levels of ultrathin films of Fe and Co. This includes both the separation into magnetization- and spin-specific spectra and an analysis of the polarization, asymmetry, and related quantities. It is shown how to selectively manipulate the manifestation of exchange- and spin-orbit effects simply by choosing different axes of quantization. Furthermore, the underlying simplicity of the results can be confirmed by comparison to a simple yet powerful single-electron picture.

Magnetic overlayers of Fe and Co have been investigated with x-ray magnetic circular dichroism in x-ray absorption spectroscopy and photoelectron spectroscopy, including spin-resolved photoelectron spectroscopy, at Beamline 4 at the Advanced Photon Source. Particular emphasis was placed upon the interrogation of the 2p levels of the Fe.

Angle-resolved photoemission experiments have been performed on USb2, and very narrow quasiparticle peaks have been observed in a band, which local spin-density approximation (LSDA) predicts to osculate the Fermi energy. The observed band is found to be depressed by 17 meV below the Fermi energy. Furthermore, the inferred quasiparticle dispersion relation for this band exhibits a kink at an energy of about 23 meV below the Fermi energy. The kink is not found in LSDA calculations and, therefore, is attributable to a change in the quasiparticle mass renormalization by a factor of approximately 2. The existence of a kink in the quasiparticle dispersion relation of a band that does not cross the Fermi energy is unprecedented. The kink in the quasiparticle dispersion relation is attributed to the effect of the interband self-energy, involving transitions from the osculating band into a band that does cross the Fermi energy.

The Nuclear Structure Laboratory (NSL) at the University of Notre Dame installed its Browne–Buechner spectrograph in the early 1970s for highly accurate energy measurements of nuclear reactions. Current renovation and upgrading of this spectrograph will enable operation of the magnet in a gas-filled mode, in particular for the study of nuclear reactions with low cross-sections of interest in nuclear astrophysics. One of the principle issues shared by measurements of extremely low abundances in Accelerator Mass Spectrometry (AMS) and nuclear astrophysics is the discrimination between the nuclei of interest and often very intense isobaric background. Recently the AMS technique of the gas-filled magnet has very successfully been used at Argonne National Laboratory (ANL) to overcome this in the study of both environmental noble gas traces ( 39 Ar) and the measurement of cross-sections of interest in stellar nucleosynthesis i.e. the 62 Ni( n , γ) 63 Ni reaction. We hope to extend these techniques further to the observations of astrophysically important reactions such as 40 Ca(α, γ) 44 Ti and 78 Kr(α, γ) 82 Sr.

The electronic structure of select Pu materials is examined by means of photoemission (PES) and model calculations. We present the first photoemission results and electronic structure calculations for the material PuIn3. Results for Pu materials, including the cubic delta-phase metal and the superconductor PuCoGa5, give indication of the 5f electrons exhibiting both localized and itinerant character. These new results for PuIn3 place this compounds also in the 5f dual nature category. The dual nature of the Pu 5f electrons demarks the boundary between localized and itinerant 5f character in the actinides.The photoemission data for δ -Pu, PuIn3 and PuCoGa5 are compared against model calculations. The calculations are a mixed level model (MLM) which is a multi-electron extension of the generalized gradient approximation. Using the MLM, one obtains good agreement for the volume and total energy minimum with 4 of 5 Pu 5f electrons localized. The calculations also agree well with the PES spectra. Other computational schemes and interpretations are also reviewed.

We present the photoemission results of two layered tetragonal compounds, the anti-ferromagnet UAsSe and ferromagnet USb 2 . We observed intriguing electronic structure for both UAsSe and USb 2 , in which relatively dispersive and narrow 5f bands are present. In the vicinity of the Fermi edge we found a very sharp photoemission peak with dispersion of several meV along the Γ to Z direction of the Brillouin zone. We also found a broader, hybridized f-character band with dispersion of several hundred meV along the Γ to X direction. Narrow and dispersive bands in these U-based magnetic materials are reminiscent of band magnetism as previously found in some transition metals.

We carried out high resolution photoelectron spectroscopy (PES) studies on a gallium stabilized δ-phase plutonium sample cleaned by laser ablation and gas dosed with O 2 . The measurements were made at a sample temperature of 77 K with an overall instrument resolution of 60 meV. At this temperature the PES strongly favor an idealized model of Pu 2 O 3 growth on the metal surface followed by PuO 2 growth on the Pu 2 O 3 . These experimental results provide an excellent benchmark for a new generation of hybrid density functional calculations that have been used to model a defective plutonium dioxide lattice. The hybrid functional predicts an insulating ground state. This is of paramount importance for the study of actinide oxides because the conventional density functional theory approaches predict them to be metals, when in fact they are insulators with significant band gaps. The calculated density of states for PuO 2 and Pu 2 O 3 agree reasonably well with the experimental data.

The structure of a 12 ML ultra-thin film of Fe on Cu(1 1 1) has been investigated using medium-energy ion scattering. The as-deposited film was found to be poorly ordered with a mean square static displacement of 0.23 A However, the order was improved by post-deposition annealing using temperatures up to 250 °C, which reduced the mean square static displacement to 0.15 A. The structure of the as-deposited film was consistent with a poorly ordered Kurjumov–Sachs coincidence—(1 1 1) fcc ∥(1 1 0) bcc , [ 1 ¯ 1 0 ] fcc ∥ [ 1 ¯ 1 1 ] bcc , [ 1 1 2 ¯ ] fcc ∥ [ 1 ¯ 1 2 ¯ ] bcc —as reported by other workers, but with some evidence of coexistence of other orientations. Upon annealing the more-ordered film structure was dominated by the Greninger–Troiano orientation—(1 1 1) fcc ∼ 1° from (1 1 0) bcc , 〈1 1 2〉 fcc ∼ 2° from [ 1 1 ¯ 0 ] bcc —with coexistence of both Kurjumov–Sachs and Nishiyama–Wassermann—(1 1 1) fcc ∥(1 1 0) bcc , [ 1 ¯ 0 1 ] fcc ∥ [ 0 0 1 ] bcc , [ 1 ¯ 2 1 ¯ ] fcc ∥ [ 1 ¯ 1 0 ] bcc —coincidences.

High resolution photoelectron spectroscopy (PES) studies were conducted on a gallium stabilized d-phase plutonium sample cleaned by laser ablation and gas dosed with O2 and H2. The measurements were made with an instrument resolution of 60 meV with the sample at 300 K, 77 K and 10 K. The PES data under these experimental conditions strongly support an idealized model with Pu2O3 growth on the metal followed by PuO2 growth on the Pu2O3 layer at low temperature. In vacuum, the PuO2 reduces to Pu2O3 at room temperature at a pressure of 6 · 10 11 Torr. In the case of H2 dosing of the surface at low temperature, the hydrogen appears to penetrate the surface and disrupt the electronic structure of the valence band as evidenced by a drop in intensity of the peak at EF which is not accompanied by a drop in the main 5f manifold at 1 eV. Studies were also carried out on the dosing of hydrogen on surfaces already dosed with both 0.5 L (Pu2O3) and 10 L (PuO2) oxygen films and show that hydrogen penetrates the 0.5 L Pu2O3 covered surface. � 2004 Elsevier B.V. All rights reserved.

The interaction of Mn with the Cu(1 1 1) surface has been investigated using the normal incidence X-ray standing wave (NIXSW) method. Analysis of the NIXSW was complicated by the apparent large shift in position of many layers of the Cu atoms relative to their expected bulk positions indicated by a change in the coherent position. Quantitative analysis of the NIXSW shows that there are at least two but possibly many sites for each element in the altered layer.

We present a theoretical model, the mixed-level model, aiming at describing metals with very complex, strongly correlated, electronic structures. As a demonstration, it is applied to the electronic structure of δ-Pu. The model reproduces the electronic-structure related properties of this complex metal; in particular, the theory is capable of reproducing the valence band photoemission spectrum of δ-Pu. We also report new experimental photoemission spectra at several photon energies. Taken together, our results provide strong evidence that the electronic structure of δ-Pu involves a 5f shell with four electrons in a localized multiplet hybridizing with valence states, and approximately one 5f electron forming a completely delocalized band state.

The structure of annealed ultra-thin Fe films on Cu(1 1 1) has been investigated using normal incidence X-ray standing wave (NIXSW). Films of between 0.5 and 5.3 monolayer equivalence (MLE) have been deposited in situ and briefly annealed to 513 K. NIXSW measurements of the (1 1 1) and ( 1 1 1) reflections using 2p3/2 photoemission show that the film is pseudomorphic up to 2 MLE, with near complete occupation of the fcc hollow sites. For this regime, the value of the (1 1 1) coherent position is equivalent to a film spacing relative to the lattice of 2.00±0.03 A. For the 5.3 MLE film, there is a drastic reduction in the ( 1 1 1) coherent fraction and shift in the ( 1 1 1) coherent position that is consistent with the transformation of the entire film to a Kurjumov-Sachs oriented bcc(1 1 0) structure.

Applications of the techniques of normal-incidence x-ray standing wave (NIXSW) and medium-energy ion scattering (MEIS) to the elucidation of the structure of an ultrathin metallic film, Co on Cu(111), are reported. NIXSW and MEIS are shown to yield valuable and complementary information on the structure of such systems, yielding both the local stacking sequence and the global site distribution. For the thinnest films of nominally two layers, the first layer is of entirely fcc registry with respect to the substrate, but in the outermost layer there is significant occupation of hcp local sites. For films up to 8 monolayers (ML) thick, the interlayer spacing of the Co layers is $0.058\ifmmode\pm\else\textpm\fi{}0.006\AA{}$ smaller than the Cu substrate (111) layer spacing. With increasing coverage, the coherent fraction of the $(1\ifmmode\bar\else\textasciimacron\fi{}11)$ NIXSW decreases rapidly, indicating that the film does not grow in a fcc continuation beyond two layers. For films in this thickness range, hcp-type stacking dominates fcc twinning by a ratio of 2:1. The variation of the $(1\ifmmode\bar\else\textasciimacron\fi{}11)$ NIXSW coherent fraction with thickness shows that the twinning occurs close to the Co/Cu interface. For thicker films of around 20 ML deposited at room temperature, medium-energy ion scattering measurements reveal a largely disordered structure. Upon annealing to 300 \ifmmode^\circ\else\textdegree\fi{}C the 20-ML films order into a hcp structure.

The technique of chemical-shift normal-incidence X-ray standing waves (CS-NIXSW) has been applied to a study of the interaction of SO2 with Cu(111), yielding quantitative information on the local adsorption geometry of adsorbed SO2 at low temperature and coadsorbed atomic sulfur with an SOx species, identified on the basis of near-edge X-ray absorption fine structure (NEXAFS) as SO3. Atomic sulfur appears to occupy a mixture of face-centred cubic and hexagonal close-packed hollow sites, while the SO3 species adsorbs with its C3v axis perpendicular to the surface atop a surface copper atom with the SO bonds out of plane such that the oxygen atoms are closer to the surface; there appears to be some local distortion of the outermost copper layers around this species. While SO2 is found to adsorb with its molecular plane essentially perpendicular to the surface, and the data are most readily interpreted in terms of a bridging geometry bonding through the oxygen atoms, there are marked inconsistencies between these results and those of an earlier surface extended XAFS (SEXAFS) investigation of this species on Cu(111), and alternative interpretations are discussed.

Surface extended X-ray absorption fine structure (SEXAFS) has been used to probe the structure of ultrathin films of iron on Cu(111). With increasing film thickness, the interatomic separation falls from 2.57 A rapidly towards that of bulk iron (2.48 A). The degree of order and coordination in the films also fall over this region. These changes are consistent with a loss of face-centred cubic structure. However, the structure does not exhibit a clear body-centred cubic SEXAFS fingerprint until around eight layers.

The polycrystalline Pt3Cr1−xMnx (x=0, …, 1) materials are a model system for the investigation of magnetic ordering and verification of band calculation schemes. Five samples with stoichiometries x=0, 0.3, 0.5, 0.7 and 1 were produced and analysed using X-ray diffraction and SEM. Subsequently, photoemission measurements were carried out at the synchrotron radiation source at Daresbury. The photoemission measurements indicated that there is little hybridisation between the Mn and Cr 3d states.

The structure of PF3 adsorbed on Cu(111) at 110 K has been determined using both near edge X-ray absorption fine structure (NEXAFS) and normal incidence X-ray standing wave (NIXSW) methods. Two X-ray reflection conditions were used, the (111) and (111), to determine the atomic positions of the phosphorus and fluorine atoms by triangulation using NIXSW, whereas NEXAFS was used to determine the alignment of the molecule. PF3 adsorbs at atop sites with the fluorine atoms away from the surface and its C3 axis aligned along the surface normal. The Cu–P distance is 2.25±0.04 A, and the distance between the copper and the fluorine layers along the C3 axis is 3.05±0.04 A. The adsorbed molecule maintains its gas-phase geometry and undergoes either free rotation about the C3 axis, or is azimuthally orientated such that the projections of the P–F bonds on to the surface point towards the next nearest neighbour copper atoms. The NIXSW analysis for the fluorine photoemission data was carried out using a backward/forward asymmetry parameter to compensate for a breakdown in the dipole approximation for photoemission that occurs for fluorine 1s photoemission under the NIXSW conditions used here.

Ultraviolet-photoemission spectroscopy has been employed to investigate the valence-band electronic structures of the magnetic alloys Co2MnSn, Cu2MnAl, and Pd2MnSn.The valence band of Co2MnSn extends to approximately 5 eV below the Fermi level with a high density of states immediately below the Fermi edge. Cu2MnAl and Pd2MnSn have valence-band widths of 6 and 7 eV, respectively, with the highest density of states lying some 3 eV below the Fermi level in each case. Photoemission measurements in the region of the Mn 3p threshold indicate that Mn 3d character extends across the full width of the valence band for all three alloys. For Pd2MnSn, additional photoemission measurements in the region of the Pd 4d Cooper minimum confirm this conclusion. Modulations in photocurrent resulting from Mn 3p-to-3d resonances across the valence band of Co2MnSn are most intense towards the bottom of the band. This is discussed in terms of possible variations in initial-state hybridization. The experimental photoemission spectra are compared with calculated spectra derived from theoretical band structures. Although there are some differences in shape, the bandwidths of the calculated spectra agree very well with the experimental results.

Recent graduates of the University of South Carolina School of Medicine (n=108) evaluated the clinical relevancy of their behavioral science curriculum. The results indicate that a body of behavioral science data are clinically relevant to physicians regardless of their specialty. Additional behavioral science content areas are clinically relevant for practitioners in particular medical specialties. Suggestions are made for the role of behavioral science material in continuing medical education.

The valence band electronic structure of the intermetallic compounds and has been investigated by means of synchrotron radiation ultraviolet photoemission. The spectra exhibit band structure extending to approximately 8 eV below the Fermi level for each alloy. Utilizing the Cooper minimum in the Pt 5d photoionization cross-section, the partial densities of states have been empirically determined. The results indicate that the d bands of the constituent metals completely overlap. The V 3d states contribute most strongly to the valence band immediately below the Fermi level. In contrast, the highest occupied density of states for the Mn 3d band lies approximately 2.6 eV below the Fermi level. For , 3p to 3d resonant photoemission confirms the results obtained at the Pt 5d Cooper minimum. However, no clear evidence for a corresponding V 3p to 3d resonance was observed in . This may indicate that the V d states in are significantly less localized than the Mn d states in . The empirical results for each alloy have been compared with theoretical calculations from the literature and provide good agreement in each case.

An approach for extraction of polycyclic aromatic hydrocarbons (PAHs) from air using solid cyclodextrin is presented. A comparison study in which β-cyclodextrin is replaced by α-cyclodextrin provides evidence that β-cyclodextrin extracts vapor phase PAHs by formation of inclusion complexes rather than by association or adsorption interactions. Thus, solid cyclodextrin complexes with vapor phase PAHs and thereby reduces their volatilities. The gas-solid interaction of the PAHs with β-cyclodextrin and the effect of β-cyclodextrin on the volatilities of these compounds are discussed. Fluorescence and absorbance spectroscopies are used to examine the variables that affect the formation of the PAH complexes with the solid cyclodextrin. The use of this system for improved ambient air sampling is proposed.

We report here a study of 9-anthroic acid (9-anthracenecarboxylic acid) in aqueous and solid solutions of β-cyclodextrin in which we demonstrate the use of cyclodextrins, in combination with fluorescence spectroscopy, to probe molecular processes. The dual fluorescence of 9-anthroic acid is dependent on the pH, the solvent, and the concentration of the acid. The origin of this dual fluorescence has been a point of controversy for many years. The small cavity of β-cyclodextrin cannot include more than one 9-anthroic acid molecule and is used in this study to distinguish between a unimolecular and bimolecular model for the dual fluorescence of 9-anthroic acid. The formation of a host/guest inclusion complex of 9-anthroic acid with β-cyclodextrin should reduce the presence of dimers, and as a result, a decrease in the corresponding fluorescence intensity would be expected if aggregation is the source of the observed dual fluorescence. However, we have observed that the broad fluorescence, which some have pre...

The two-laser pump-probe technique has been used to study the kinetics of the reaction of CN radicals with C3H6, CD3C2H3, C3D6, C2H3CN, C3H4 and C4H6 at temperatures between 297 and 740 K. CN was generaged by 248-nm photolysis of ICN. Laser-induced fluorescence of the CN radical has been used for its detection by CN (B←X) excitation. The values for the rate constants, given in units of cm3/s, are reported as: k(C3H6)=10−9.88±0.10exp(+244±96.3/T), k(C3H3D3) = 10−9.76±0.04 exp (+143.4±35.1/T), k(C3D6)=10−9.87±0.05exp(+231.4±47.01/T, k(C2H3CN)=10−10.52±0.02exp(+103.6±20.3/T), k(C3H4)=10−9.58±0.08 ×exp(+167.4±73.7/T), k(C4H6)=10−9.59±0.04exp(+169.2±33.1/T). The absolute rates of CN reactions with CH3CHCH2, CD3CHCH2 and CD3CDCD2 are essentially the same and are somewhat faster than that of the CN+C2H4 reaction. This suggests that the CN+C3H6 reaction occurs primarily by addition to the unsaturated bond and the CH3 group enhances the addition process slightly. The rate of the CN+CH2CHCN reaction, however, was found to be a factor of six slower than that of CN+C2H4, indicating a substantial electron withdrawing effect of the CN group in vinyl cyanide which results in the reduction in the addition rate. The rates for CN reaction with CH2CCH2 and CH2CHCHCH2 are approximately the same and are twice that of CN+C2H4.

We present a multitechnique approach to study the detailed chemical and magnetic structure of uranium/gadolinium multilayers. At low temperature the saturation magnetization is found to be $\ensuremath{\sim}60\mathrm{%}$ of that of bulk gadolinium. We address this problem, which is found in many other multilayers and suggest a model that may have wider applications. transmission electron microscopy images indicate a microstructure, consistent with a columnar growth of Gd with crystallites of the order $20\ensuremath{\rightarrow}100\text{ }\text{\AA{}}$. Off-specular neutron scattering is most strongly visible at saturation field, indicating that Gd moments are not aligned with the applied field. X-ray resonant magnetic scattering provides proof of coupled in-plane length scales for both the structural and the magnetic roughness. A detailed x-ray scattering study of both the specular and off-specular reflectivities has been used to investigate the in-plane structure of the multilayers. We calculate the roughness and transverse correlation cut-off length, ${\ensuremath{\xi}}_{\text{x}}=120\ifmmode\pm\else\textpm\fi{}30\text{ }\text{\AA{}}$, and present a simple model to determine an average column size of $27\ifmmode\pm\else\textpm\fi{}6\text{ }\text{\AA{}}$ and a reduction in the magnetic saturation of $\ensuremath{\sim}40\mathrm{%}$.

Potential benefits of heart transplantation are limited by the severe donor organ shortage. The AbioCor implantable replacement heart has been developed as a potential alternative to heart transplantation. We report our initial experience with the AbioCor in a bovine model. A right thoracotomy was performed for access to the heart and great vessels. After initiation of cardiopulmonary bypass, excision of the native ventricles was followed by orthotopic placement of the IRH and complete implantation of the transcutaneous energy transfer coil, controller, and battery pack. Invasive monitoring of IVC, SVC, carotid artery, pulmonary artery, and left atrial (LA) pressures was performed in all animals. Twelve calves have undergone implantation of the AbioCor. There were three early deaths, one from bleeding, one from respiratory failure, and one from neurodysfunction from low flow during CPB. Nine animals have had a normal recovery and survived a mean of 24.5 days (range, 4-48 days). All the animals have demonstrated excellent hemodynamics with the maintenance of normal pressures in the LA, SVC, IVC, pulmonary artery, and aorta. Adjustment of the right-sided internal hydraulic fluid shunt has allowed for control of right-left balance and, thereby, manipulation of left and right side filling pressures. Late morbidity has consisted of neck wound infection and sepsis, pneumonia, and bleeding. Successful orthotopic implantation of all components of the AbioCor has been achieved in a bovine model. This device has demonstrated restoration of normal hemodynamics and excellent function of the atrial hydraulic shunt to achieve right-left balance.

Single crystals of ferromagnetic UAsSe have been investigated by angle-resolved photoemission spectroscopy (ARPES) in the photon energy range between 20 eV and 110 eV. Electron kinetic energy intensities are collected as a function of angle and mapped onto the materials reciprocal space. Energy-band mapping has been carried out both for a several-eV-wide energy interval as well as for a narrow energy interval of less than 1 eV from the Fermi energy. The main features of the deduced energy bands can be explained by band-structure calculations. In the interval close to the Fermi energy, the very high energy and momentum resolution allows the observation of a narrow, yet dispersive photoemission peak mainly of 5f character situated within 50 meV of the Fermi energy. The Lorentzian linewidth was found to be about 35 meV with a dispersion of 30 meV along the Gamma to Z direction and 40 meV dispersion along the Gamma to X direction in the Brillouin zone. We have also found broader (linewidth about 70 meV), hybridized f-character bands with a conventional dispersion of about 1 eV along the Gamma to X and the Z to R directions in the Brillouin zone. An intriguing electronic structure emerges for UAsSe in which both relatively dispersive and narrow 5f bands are present. The occurrence of 5f-band dispersions stipulates that the electronic structure of UAsSe requires lattice periodicity to be taken into account.

The standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy [1], x-ray absorption spectroscopy [1,2,3,4], electron energy loss spectroscopy [2,3,4], Fano Effect measurements [5], and Bremstrahlung Isochromat Spectroscopy [6], including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples. [2,3,6]

Understanding the behavior of 5f electrons remains an unrealized ambition of condensed matter physics [1,2]. Recently, there has been a large amount of interest in the actinides, particularly plutonium, driven by the complex and intriguing behavior of Pu and several of its compounds [3-5]. This has prompted both theoretical and experimental investigations of 5f metals and compounds. Of the different allotropes of Pu, the d-phase is of particular interest because of the high symmetry crystal structure and the stability of the phase to low temperatures when alloyed with small amounts of trivalent elements. Consequently much of the recent experimental and theoretical work has focused on this allotrope. From an experimental point of view, the reactivity and radioactivity of Pu, and the complexity of the phase diagram, make it exceedingly complicated to collect high-quality data. Investigations of these complex behaviors all point back to being caused by the intriguing interplay of the various electron states and in particular the behavior of the 5f states. While there are a number of ongoing experimental efforts directed at determining the occupied electronic structure of Pu, there is essentially no experimental data on the unoccupied electronic structure of Pu. We aim to determine the conductionmore » band (unoccupied) electronic structure of Pu and other actinides in a phase specific fashion and emphasizing bulk contributions by using Nano-focussed Bremstrahlung Isochromat Spectroscopy (nBIS). Bremstrahlung Isochromat Spectroscopy (BIS) is the high-energy variant of inverse photoelectron spectroscopy (IPES: electron in, photon out), which is essentially the time reversal of photoelectron spectroscopy (photon in, electron out). IPES can be used to follow the dispersion of electronic states in ordered samples. Owing to its low energies, IPES is usually very surface sensitive. However, by working at higher energies (>200 eV), we will sample preferentially for bulk properties, downgrading the impact of surface effects. Thus, from BIS, we would have a direct measure of the conduction band or unoccupied electronic structure of the bulk Pu.« less

The electronic structure of Pu materials is examined using photoelectron spectroscopy. For delta-phase Pu metal as well as PuCoGa5 and PuIn3, the 5f electrons appear to be at the threshold between localized and itinerant character. A mixed level model computational scheme is used which results in non-magnetic solutions for the electronic structure and agrees well with the photoemission measurements. Several other computational schemes are assessed against photoemission results for delta Pu. Additional insight is provided by O2 and H2 dosing of the delta Pu samples and consideration of surface effects. The experimental and computational results are consistent with the 5f electrons in Pu materials exhibiting a dual nature with some fraction of the 5f levels localized and not participating in the bonding while the other fraction of 5f character is involved in bonding and hybridization with the conduction electrons.

Our electron photoemission experiments demonstrate that the magnetization of the ferromagnetic state of UTe is proportional to the binding energy of the hybridized band centered around 50 meV below EF. This proportionality is direct evidence that the ferromagnetism of UTe is itinerant; i.e., the 5f electrons are not fully localized close to the atomic core. This mechanism of itinerant ferromagnetism differs from the traditional picture for 5f-electron magnetism in an essential and a novel way. We propose a simple model for the observed proportionality between the temperature dependence of the magnetization and the binding energy of the hybridized band near EF. This model allows us to estimate the effective magnetic interaction and to identify signatures of itinerant ferromagnetism in other materials. DOI: 10.1103/PhysRevLett.93.267205

Single crystals of $\mathrm{USb}$, $\mathrm{NpSb}$, $\mathrm{PuSb}$, $\mathrm{UTe}$, $\mathrm{NpTe}$ and $\mathrm{PuTe}$ were investigated by photoelectron spectroscopy, this included angular-resolved studies on the U compounds. The spectral features show little dependence on incident photon energy, suggesting they all contain comparable amounts of $5f$ and conduction character. In the case of $\mathrm{USb}$ interesting (and unexpected) momentum dependent effects are observed in the angular-resolved studies. In $\mathrm{PuTe}$, we confirm the presence of a strong three-peak structure near ${E}_{F}$, which has been interpreted as the signature of an intermediate valence state in similar materials. Hybridization of the $5f$ electrons with the conduction band is found within the series and the level of localization is shown to increase from $\mathrm{Te}$ to $\mathrm{Sb}$. A surprising correlation between the binding energy of the peak bearing most of the $5f$ weight in the photoemission spectrum and the magnetic moment is discovered within the series, for which some explanations are suggested.