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Summary Increasingly, weeds have been taking on global distributions. With the proliferation of invasive weeds has come the challenge of managing these species over broad geographical regions, with diverse habitats and political jurisdictions. Here, we review the management of Mikania micrantha Kunth (Asteraceae; mile-a-minute) throughout its invaded range, extending through most of the Pacific islands and southern and south-east Asia. Context matters when determining the best course of action for managing M. micrantha, as it has invaded a large variety of agricultural and natural systems. In Queensland, Australia and Florida, USA, M. micrantha has been targeted in relatively successful eradication campaigns, highlighting the importance of early detection and rapid response methods, while elsewhere in its invaded range, populations are either still increasing or showing limited signs of decline. An inter-regional approach to research and management should incorporate successful management strategies employed throughout the invaded range including, but not limited to, chemical and cultural control practices, manual and mechanical control, classical biological control using the rust fungus Puccinia spegazzinii, plant–plant competition and integrated approaches utilising two or more control methods concurrently. Additional knowledge of M. micrantha genetics is required to determine if management approaches could be fine-tuned for particular populations. Countries bordering the Mekong River formed a network in 2011 to co-ordinate the management of invasive species such as M. micrantha. Expanding such a collaborative approach to other regions could further reduce populations of M. micrantha and limit its spread.

Background: Neoadjuvant systemic therapy (NST) is the standard treatment for locally advanced breast cancer. Early studies have demonstrated that the rate of breast conservation was significantly increased and NST is now widely applied to operable breast cancer to increase breast conservation rate and to achieve better cosmetic outcome after breast conservative surgery (BCS). For patients who achieved pathologic complete response (pCR), they were perfect candidate for BCS. However, data from prospectively randomized trials have shown that, with the significantly increase of pCR by adding new drugs in the neoadjuvant regimen, BCS rate does not significantly increased. The purpose of current study is to identify factors that have influence on surgical option in patients that have achieved complete response in the breast after NST. Methods: From January 2009 to July 2016, 1150 patients with breast cancer received NST in our institute. There were 103 patients achieved complete response (CR) in the breast and were included in current analysis. Medical records were reviewed regarding to individual surgeon, pre-NST clinicopathologic characteristics, and post-NST image findings. Risk factors for mastectomy were assessed by univariate and multivariate analyses. Results: Of the 103 patients who achieved CR in the breast, 40 of them (38.8%) received mastectomy. In univariate analysis, physician factor, larger initial tumor size, advanced clinical stages, as well as post-NST image findings including skin change, residual tumor ≥3 cm, short nipple-tumor distance, and residual axillary lymph node(LN) on ultrasound and segmental/diffuse distribution of malignant calcification on mammography were associated with more mastectomy. In multivariate analysis, physician factor (OR=5.192, CI [1.562 – 17.257], p=0.021), residual axillary LN on echography (OR=4.000, CI [1.552 – 10.319], p=0.004), and segmental/diffuse distribution of malignant calcification on mammography (OR=7.500, CI [1.819 – 30.916], p=0.018) were independently related to mastectomy in patients who achieved CR in the breast after NST. Conclusion: Physician factor, residual axillary LN and segmental/diffuse malignant calcifications were risk factors for mastectomy in patients who achieved CR in the breast after NST. In addition to embrace current treatment guidelines of surgical management after NST, our data provide valuable additional information to avoid unnecessary mastectomy. Citation Format: Kou H-W, Shen S-C, Chen S-C. Factors impacting surgical option in patients who achieved complete response in the breast after neoadjuvant systemic therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-13-10.

To uncover the involvement of long non-coding RNA (lncRNA) MALAT1 in the proliferation and apoptosis of vascular smooth muscle cells (VSMCs), and the underlying mechanism.Relative levels of MALAT1, microRNA-124-3p (miRNA-124-3p) and peroxisome proliferator-activated receptor alpha (PPARα) in VSMCs treated with different doses of oxidized low-density lipoprotein (ox-LDL) for different time points were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Proliferative and apoptotic changes of VSMCs overexpressing MALAT1 were assessed. Subcellular distribution of MALAT1 was analyzed. The potential binding among MALAT1, miRNA-124-3p and PPARα was determined by dual-luciferase reporter gene assay, and their interaction was determined as well. Finally, the influences of MALAT1/miRNA-124-3p/PPARα regulatory loop on the proliferative and apoptotic abilities of VSMCs were examined.MALAT1 and PPARα were dose-dependently downregulated in ox-LDL-treated VSMCs, whereas miRNA-124-3p was gradually upregulated. Overexpression of MALAT1 attenuated viability and induced apoptosis in ox-LDL-treated VSMCs. Moreover, MALAT1 was mainly distributed in the nucleus. Dual-luciferase reporter gene assay verified that MALAT1 could sponge miRNA-124-3p, and moreover, PPARα was the direct target of miRNA-124-3p. MALAT1 negatively regulated miRNA-124-3p level and miRNA-124-3p negatively regulated PPARα level as well. Finally, MALAT1/miRNA-124-3p/PPARα regulatory loop was identified to regulate the viability and apoptosis of ox-LDL-treated VSMCs.LncRNA MALAT1 mediates proliferation and apoptosis of VSMCs by sponging miRNA-124-3p to positively regulate PPARα level.

Tetragonal α-FeSe flakes were fabricated by a simple method. Enhancement of superconductivity was observed in the quenched samples. The properties were characterized by X-ray diffraction, a superconductivity quantum interference device, and physical property measurement system. It is interesting that the superconducting transition temperature of the quenched samples is about 2 K higher than that of unquenched samples, but after reannealed, the enhancement of superconductivity disappeared. The reduction of the c/a ratio might be responsible for the enhancement of superconductivity in the quenched FeSe flakes.

In the presence of 1,12-diaminododecane (DADD), tetragonal ZrO2 nanoparticles (ca. 10 nm) with high phase purity (monoclinic volume content: less than 0.1) and large surface area (100 m2/g) and pure monoclinic ZrO2 nanorods (aspect ratio of ca. 10) have been successfully prepared upon hydrothermal processing at 230 °C for 3 days of zirconyl nitrate-derived hydrous zirconia gels at different pH values. The complementary data from FTIR, Raman, TGA/DTG confirm the presence of hydrocarbon fragments (1–3 wt%) on the surface of DADD-derived zirconia nanocrystals. These organic residues account for their features in the phase composition, particle size and morphology, and surface wettability.

THz spectra for some amino acids, peptide and protein have been measured by use of commercial and optically compensated FTS spectrometers. A lot of sharp spectral lines have been observed below 7 THz and attributed, tentatively and in general, to hydrogen bonds and weak intermolecular interactions for the amino-acids and simple peptides, but the detailed explanation is still lack and leaving a big room for further investigation.

Multiple confined-state transitions within surface quantum dots deposited on In 0.35 Ga 0.65 As template grown on GaAs (311)B substrate, as well as signals from all other relevant portions of the samples including buried QDs, In 0.35 Ga 0.65 As template, and GaAs-related layers, at 77 K, were obtained in a piezomodulation reflectance spectroscopy (PzR) study. The measured transition energies were accurately determined using a Gaussian lineshape fit based on the reference of PL results. Four factors caused the large energy shift (larger than 400 meV) of confined states within SQDs compared to the buried QDs.

MgO particles with different morphologies and textural properties are prepared and tested as solid bases for various ligand-free Heck reactions at low Pd loading (0.05 mol%). Moderate (57%) to high (99.5%) conversions have been achieved with fresh porous polyhedral MgO particles. Used MgO particles are recovered by filtration and reactivated by calcination at 500 °C in air. The reactivated MgO particles have been used four times as solid base for arylation of styrene with bromobenzene with conversion of 70–86% and turnover number of 1411–1714.

Supercritical fluid extraction was evaluated for removing surfactants from freshly synthesized molecular sieve powders possessing different pore sizes. In our study, methanol- or water-enhanced supercritical CO2 extraction was carried out on as-synthesized microporous and mesoporous material powders. The results showed that very high surfactant recovery (over 80%) could be achieved from large pore-sized mesoporous materials by using the SFE method, while the surfactant recovery is rather low from small pore-sized microporous zeolite materials. Supercritical fluid extraction technology may provide a potential method for large-scale production of mesoporous materials with effective surfactant recovery that is extremely efficient.

Mesoporous molecular sieves like SBA-1, SBA-3, MCM-41 and MCM-48 are generally synthesized by using a quaternary ammonium surfactant as a structure-directing agent to form a porous silica framework. The used templating agent is conventionally removed for producing mesopores by calcination at high temperature. In this study, supercritical fluid extraction (SFE) has been employed to remove organic templates from these materials. We found that more than 80% of the templating agent can be successfully removed by using this technique. Among these materials, SBA-3 was observed to experience the collapse of mesoporous structures upon the SFE process. Thus, we have proposed pre-SFE thermal aging as a curing treatment method and found that it has significantly improved the mesoporous structural stability of SBA-3. In the meantime, this curing method has lead to these SFE-processed materials with better ordered mesoporous structures, such as SBA-3 having specific surface area as large as 1670 m 2 /g.

SBA-3 with pore sizes of 22–25 A has been successfully prepared by TEOS liquid phase deposition on the pristine SBA-3 with a pore size of ca. 27 A. After the first TEOS modification, the resulting sample (Name: M 1 /SBA-3) shows obvious changes in textural properties. As compared to SBA-3, M 1 /SBA-3 has negligible micropores, its BET surface area and pore volume decrease by 24% and 40% respectively, its wall thickness increases from 15 A to 22 A and its pore size decreases from 27 A to 23 A. The presence of ethoxysilyl groups on M 1 /SBA-3 is supported by FTIR and carbon content measurement, and their loading amount is estimated to be ca. 5.7 wt% by TGA. The second TEOS modification is less efficient to change the textural properties of SBA-3 owing to its lower loading (ca. 1.3 wt%).

Nanocrystalline Ga–Al–Zn complex-oxide (designated here as nano-GAZ) has been successfully synthesized using hydrothermal method. Using TEM, BET, FTIR, DTA–TGA, and XRD, synthesized nano-GAZ particles are shown as high-surface-area nanoparticles comprising typical spinel crystal structures. The nano-GAZ catalyst was tested as a new deNPAC catalyst, using pyridine as the model NPAC compound. The reaction results show that pyridine could be completely oxidized over nano-GAZ catalyst above 400 °C. Furthermore, NO formation was significantly decreased due to the excellent performance of the nano-GAZ catalyst for the selective catalytic reduction of NOx with hydrocarbon in the presence of excess oxygen. An optimal reaction temperature at around 440–500 °C was observed to achieve complete catalytic oxidation of pyridine with the lowest NOx formation. These results demonstrate a promising approach for dual-mitigation of NPAC and NOx pollutants using nano-GAZ catalyst.

Evidences indicating the presence of micropores in SBA-3 are presented in this work. These include (1) large low-pressure adsorbed volume of liquid N 2 (e.g., 0.20 cm 3 /g at 0.001 P / P 0 ); (2) selective blocking of micropores by TEOS grafting; (3) evaluation of micropore volume (0.015 cm 3 /g) and micropore surface area (135 m 2 /g) from the α s -plot method; (4) geometric consideration: w d S / V = 5.1; (5) two-step adsorption/desorption processes of n -heptane vapor on SBA-3. As a result of the presence of these micropores in the silica wall of SBA-3, it can serve as a template to produce ordered carbon replicas.

Based on a series of numerical results calculated by the transfer-matrix method, we find that the λ/4 rule for one-dimensional (1D) optical films is also valid for 2D and 3D photonic crystals (PCs) in designing a large high-reflectance region (HRR), if the 1D counterpart approximation is used for them. A detailed process of the 1D counterpart approximation is described. The results of the 1D counterparts of real 2D and 3D PCs are in good agreement with the λ/4 rule. Therefore, the λ/4 rule can be extended to 2D and 3D structures for designing large HRRs.

The photoconductivity of BaTiO 2.5 with oxygen vacancy has been studied by the linear muffin-tin orbital method in the atomic sphere approximation (LMTO-ASA). The ground-state structure of BaTiO 2.5 is obtained by minimization of the total energy. The partial densities of states show that the occupied states at the bottom of the conduction band have primarily Ti d orbital character. The photoconductivity shows that two novel features, in the low energy side, can be attributed to the intraband transition of free electronic carriers in the vicinity of the Fermi level and the interband transition of the Ti 3d( yz ) related band states, to the Ti 3d( xy , xz ) related band states, respectively. In addition, it is also found that the anisotropy of photoconductivity is enhanced because of the introduction of oxygen vacancy. The system can show the conductive behavior of electronic carriers, which is qualitatively in agreement with a recent experimental finding.

The effects of preparation method for beta-zeolite, Co-precursor, loading method and different type of reductants on the performance of Co/beta-zeolite catalyst for HC-selective catalytic reduction (SCR) of NO have been investigated. The catalyst properties and nature of active sites have been characterized by N2 adsorption–desorption isotherms, X-ray diffraction (XRD), thermogravimetric analysis (TGA), TPR, X-ray photoelectron spectroscopy (XPS) and NMR. The catalyst activity is not affected by the type of cobalt precursor but is significantly influenced by the cobalt loading methods. The ion-exchange method results in a much higher activity than impregnation method. Although there is little influence of the silica source on the catalyst properties, the preparation condition of support beta-zeolite is found to substantially affect the activity of the resulting catalyst. The low hydrothermal synthesis temperature causes the presence of amorphous mesoporous phase, making the resulting catalyst poorly resistant to steam. The catalytic performance is substantially affected by different reductants used, with propane performing as a proper reductant for SCR of NO.

The effects of different synthesis conditions for MFI and the different locations of Co 2+ on MFI on the catalyst properties for the selective catalytic reduction of NO by C 3 H 8 [C 3 H 8 –SCR] in the presence of excess oxygen were investigated, and the nature of Co 2+ was characterized by XRD, FTIR, H 2 -TPR, XPS, and DTG. H 2 -TPR shows that the exchanged Co ions in MFI are nonreducible even at 750 °C, while the reduction temperature of incorporated Co is at 690 °C. Three types of DTG peaks, which correspond to different temperatures for the thermal decomposition or disassociation of TPA, are observed in the differential thermogravimetric (DTG) analysis of the as-synthesized MFI prepared under different conditions, and are related well to C 3 H 8 –SCR of NO for three different types of Co sites in MFI: incorporated Co 2+ site and two different exchanged Co 2+ sites, respectively. The incorporated Co 2+ in MFI with the DTG peak temperature at 418 °C is almost inactive for C 3 H 8 –SCR of NO. For the Co 2+ -exchanged MFI, the sample with a low Co 2+ -exchange degree has a higher TOF for NO reduction than that having a higher Co 2+ -exchange degree, indicating that at least two types of Co 2+ sites exist in the Co 2+ -exchanged MFI sample. The corresponding DTG peak temperatures located at 455 and 481 °C show two types of exchanged Co ion sites having different surface energies for different activities for SCR of NO, with the Co 2+ site with higher surface energy having higher specific catalytic activity for NO reduction. The exchange degree and position of Co 2+ depend on the alkalinity of the hydrothermal synthesis condition and the sodium content of the resulting Co 2+ -exchanged MFI.

A series of beta ( β ) zeolites has been synthesized in a fluoride medium and characterized by different techniques. XRD showed that the majority of FSi β , FPt β , FPd β , and FW β materials consisted of polymorph A. W and Al were incorporated into the framework of β , while Pt and Pd existed on the surface of β in the form of PtO x or PdO x oxides. The framework structures of FSi β , FPt β , and FPd β were almost identical, as proven by 29 Si MAS NMR and FTIR spectra. The relative coverage of surface –OH groups decreased in the sequence H β >HZSM-5>FAl β >FW β >FPd β >FPt β >FSi β (1)>FSi β (2). SEM revealed an especially uniform crystalline morphology of FSi β (2) nucleated spontaneously and a mixed morphology of FSi β (1), FW β , FPt β , and FPd β induced by seeding H β . The reduced FPt β and FPd β were catalytically active for the asymmetric hydrogenation of tiglic acid with an appreciable enantiomeric excess value of about 9–11% without adding chiral modifiers.

A fixed-bed reactor was utilized to investigate the activities of six metal catalysts (1% Pt, 1% Pd, 1% Ru, 5% Co, 5% Mo and 5% W on γ-Al2O3 support) in decomposing naphthalene, based on the production of carbon dioxide and the disappearance of naphthalene. The Pt and Pd catalysts were found to exhibit higher naphthalene oxidizing activity than other catalysts tested. The Co catalysts, whose activity is similar to that of the Ru catalysts, are promising for naphthalene oxidation. The kinetic results of naphthalene oxidation over 1% Pt/γ-Al2O3 catalysts are reported for the first time. A first-order reaction with respect to Pnaphthalene was found, while the reaction order with respect to PO2 decreased with increasing reaction temperatures. A Langmuir–Hinshelwood model was used to describe the observed kinetic behavior. Oxygen adsorption dominates at higher reaction temperatures (>140 °C), and consequently the oxidation of naphthalene over the Pt catalysts appeared to be insensitive to PO2.

The selective catalytic reduction of NO by C3H6 and C3H8 in the presence of 5% O2 over 0.5–2% Pt supported on siliceous MCM-41 has been studied in detail. Pt/MCM-41 shows better activity for NO reduction than Pt/SiO2 and Pt/Al2O3 under the same reaction conditions due to the larger surface area and pore volume of MCM-41. Two types of Pt species having different reduction temperatures (50–200, 350–500 °C, respectively) are formed on Pt/MCM-41. The Pt species having lower reduction temperature is suggested to be responsible for the selective reduction of NO. A redox mechanism is used to explain this behavior. In addition to its high stability in the presence of water vapor, Pt/MCM-41 shows high resistance to SO2 without irreversible deactivation due to its weak interaction with SO2. The activity of Pt/MCM-41 catalyst is found to be improved in the presence of Al species both in the framework or on the surface of MCM-41 support, possibly due to the improvement of the acidity of Pt/MCM-41 by Al species. In situ XRD result indicates that the surface Al-species prevent the active Pt from sintering at high temperature, hence improving the thermal stability of Pt/MCM-41. Having additive Ru species, Pt/Ru/Si-MCM-41 is found to widen the reaction window and decrease the selectivity of the conversion of NO to N2O during the SCR of NO; this is an important finding for overcoming the main shortcoming of Pt-based catalyst.

Using material chip technology, large area n-on-p planar junctions with various boron implantation doses have been fabricated on an Hg1−xCdxTe (x = 0.291) film, similarly grown using molecular beam epitaxy, for the mid-infrared wavelength range. The current–voltage characteristics of p–n junctions have been measured on a cold stage at 77 K and an optimized ion implantation dose has been discovered. Zero bias resistance of all the junctions has been calculated and shows distinct dependence upon the boron implantation doses.

A photonic quantum-well is constructed by sandwiching a uniform medium between two photonic barriers due to the photonic band gap mismatch, similar to electronic quantum well. The transmission coefficient is calculated by a plane-wave expansion method in combination with multiple-scattering techniques. The transmission peaks indicate that some photonic states exist in a quantized way, satisfying a quantized frequency relation. We also show that the finite photonic potential barrier plays different confined roles on the different photonic levels. The positions and number of the resonant peaks can be artificially tuned by varying the well width. By appropriately choosing the parameters of the well and barrier, a high-quality multichannel filtering can be achieved.

Micro-photoluminescence (μ-PL) line scanning across a single V-groove, GaAs/AlGaAs quantum wire (QWR) has been performed at room temperature, revealing a clear spatial-dependence of the PL. After fitting each PL spectrum by multi-Gaussian line shapes, intensity profiles of each PL component from confined structures have been obtained as functions of the scanning position. The PL quenching of a side-wall quantum well (SQWL) has been recognized in a certain area in the vicinity of the QWR and is interpreted by carrier transfer into the QWR within effective transfer length. By simulating the carrier-transfer process from SQWL to QWR as a convolution of a step function for carrier distribution and a Gaussian function for exciting laser irradiance, the effective transfer length of about 1.8±0.3 µm has, therefore, been concluded.

The reaction mechanism for the selective catalytic reduction (SCR) of nitric oxide (NO) over Pt/Si-MCM-41 catalyst has been studied by XPS and in-situ Fourier transform infrared (FTIR) spectroscopies as well as TPR. The XPS results indicate that Pt species are reduced during the reaction of NO-SCR in the presence of excess oxygen. The reduced Pt species are found not to be completely oxidised after they have been in contact with NO or O2 at the reaction temperature. FTIR results indicate that CO is one of the reaction intermediates taking part in the selective reduction of NO. The possible reaction mechanism for the selective catalytic reduction of NO over Pt/Si-MCM-41 catalyst is proposed.

The effects of Si/Al ratio of Al-containing MCM-41 materials prepared by either aluminum incorporation or postsynthesis alumination on the formation or prevention of structural defects and improvement of hydrothermal stability of MCM-41 have been investigated in detail. The states of Al and Si in the Al-containing materials are analyzed by MAS NMR, and the detailed properties of the materials subjected to hydrothermal treatment under different conditions are characterized by ICP, XRD, N2 adsorption, and FTIR. XRD and N2 adsorption results indicate that the amount of structural defects formed during calcination increases with the amount of aluminum in Si−Al−MCM-41. After calcination, Si−MCM-41 and Si−Al−MCM-41 having high Si/Al ratio (≥50) still show uniform pore structures, but structural defects are formed on the calcined Al-rich MCM-41 (Si/Al = 25 or 10). Structural defects are formed on all Si−Al−MCM-41 materials during hydrothermal treatment in boiling water. Although the mesoporous framework of Si−Al...

Phosphorus species could be grafted onto the surface of Si-MCM-41 by simply treating Si-MCM-41 with phosphoric acid for a very short period, followed by high temperature calcination. The existence and state of surface phosphorus species grafted on Si-MCM-41 are confirmed by XPS measurement. Using XRD and N2 adsorption measurements, the uniform mesoporous structure of MCM-41 is shown to be quite stable under phosphoric acid treatment. FTIR results show that the surface phosphorus species grafted onto the surface of MCM-41 can selectively increase the number of Bronsted acid sites on the surface without forming any Lewis acid sites. Using NH3–TPD, the mild acidity of the generated Bronsted acid sites on phosphorus-containing MCM-41 significantly enhances its catalytic activity for the dehydration of isopropanol.

A 69-year-old woman with hypertension presented to the emergency room with severe pulsatile pain around the left orbital area and diplopia for 2 days. Neurological examination revealed paresthesia over the upper two-thirds of left face innervated by the ophthalmic and maxillary divisions of trigeminal nerve and diplopia secondary to left abducens nerve palsy. Brain noncontrast computed tomography (CT) showed a 2.5 × 2.5 × 2.0 cm hyperdense mass over left cavernous sinus suggestive of thrombus formation (Fig. 1a). CT angiography (CTA) showed a giant, partially thrombosed aneurysm arising from the intracavernous internal carotid artery (ICA) (Fig. 1b). Digital subtraction angiography (DSA) showed a large persistent primitive trigeminal artery (PPTA) connecting the ICA to the distal part of the hypoplastic middle basilar artery (BA), with a 1.2 × 1.2 × 1.0 cm aneurysm sac at the origin of PPTA and hypoplasia in the left vertebral artery (VA). (Fig. 1c–f) Steroid therapy was prescribed initially and endovascular surgery was arranged. Aspirin (400 mg) and clopidogrel (300 mg) were administered before the treatment. All procedures were performed under general anesthesia and full heparinization. The covered stent, Jostent stent graft (previously JoMed, Helsingborg, Sweden; now Abbott Vascular, Redwood City, California, USA), was successfully deployed at left ICA to cover the orifice of persistent primitive trigeminal artery (Fig. 2). The postoperative course was uneventful. Trigeminal neuralgia improved immediately after treatment but diplopia persisted. One-year follow-up of left ICA DSA showed ICA patency was preserved and there was no recurrent aneurysm. In addition, the right VA DSA showed a small remnant of PPTA supplied by the vertebrobasilar artery (Fig. 3). The clinical situation at one-year follow-up showed complete resolution of trigeminal neuralIntroduction

A pseudomorphic Al0.5Ga0.5As/In0.25Ga0.75As/GaAs asymmetric quantum wire (QWR) structure was grown on GaAs V-grooved substrate by low pressure metal organic vapor phase epitaxy. The formation of crescent shaped QWRs at the bottom of the V-grooves was confirmed by both transmission electron microscopy and photoluminescence (PL) spectra. The temperature dependence of PL spectra demonstrated a fast decrease of the sidewall quantum well PL intensity with increasing temperature, which originates from relaxation of carriers from well to wire region. The self-aligned dual implantation technique was successfully used to selectively disable the adjacent quantum structures. Decrease of the PL intensity of QWR at 8 K was observed after selective implantation, which resulted from a decreased number of carriers relaxed from adjacent quantum structures.

Three different types of Ru/MCM-41 catalysts were prepared by impregnating MCM-41, which had a high surface area of 1200 m2 g−1 and a very uniform mesoporous size of 27 A, with RuCl3 or Ru(OH)3 or Ru3(CO)12. The catalysts were characterized by surface area and pore size distribution. The state of Ru and its dispersion on MCM-41 surface was studied by XPS and chemisorption, respectively. The conversion of nitrous oxide to nitrogen and oxygen, by catalytic decomposition and reduction reactions, was studied using the synthesized Ru/MCM-41 catalysts. The effects of the amount of Ru loading, the type of Ru precursor, catalyst pore size, as well as the presence of oxygen, carbon monoxide, and moisture in the feed stream on the catalyst activities for the catalytic decomposition and reduction of N2O were investigated. The results show that the Ru/MCM-41 catalyst prepared from Ru(OH)3 as the catalyst precursor and having a 5 wt.% Ru loading is promising for the catalytic decomposition and reduction of N2O.

Reaction kinetics for selective catalytic reduction (SCR) of nitric oxide (NO) over 1% Pt/MCM-41 catalyst has been investigated at temperatures ranging 150–500°C under steady and transient state conditions. The reduction of NO is found to be promoted by a small amount of oxygen when the concentration of oxygen is less than that of the critical oxygen concentration required for stoichiometric oxidation of C3H6. Above the critical oxygen concentration, an optimal reaction temperature for optimal NO conversion is observed and the optimal NO conversion decreases with the increase of oxygen concentration. Two distinct kinetic regions are observed: one at the reaction temperature below and the other one above that required for optimal NO conversion. The NO reduction rate is suggested to be controlled by the activation rate of C3H6 at low temperatures and by the external diffusion rate of reactants at high temperatures.

We report microphotoluminescence (μ-PL) mappings of CdZnTe wafers on micrometer and millimeter scales. The acquired PL spectra have been fitted to a model based on band-to-band transition including the contribution of localized states in the energy gap. The fitting yields energy gap Eg, which is correlated to the Zn fraction x in Cd1−xZnxTe. The statistics of large numbers of fitted Eg reveal the inhomogeneity of the Zn composition while the map of Eg gives the distribution of Zn atoms. The comparison between the PL mappings before and after epi-ready chemomechanical processing show a great improvement in homogeneity due to the removal of surface defects and damage by the processing. Our results demonstrate the feasibility of PL mapping in determining the Zn composition homogeneity and distribution in a CdZnTe wafer.

Proton implantation followed by rapid thermal annealing was used to tune the spectral response of the quantum-well infrared photodetectors (QWIPs). Various implantation schemes, such as single low energy implantation, multiple energy implantation, and single high energy implantation were compared for tuning the wavelength of QWIPs. Large redshift of the QWIPs’ response wavelength with either narrowed or broadened spectrum was obtained after interdiffusion. Comparatively, the single high energy scheme is the simplest and most effective method. Furthermore, by applying a two-step implant–anneal sequence to single high energy implantation, the device wavelength was further shifted with improved photocurrent signal, making it promising to achieve the fabrication of multi-color detectors.

We report the temperature dependence of the photoluminescence from our V-grooved GaAs/AlGaAs quantum wires. Based on the specially resolved luminescence results, our results show that in the processes of real space carrier transfer from the vertical quantum well region to quantum wire region. a 3.5 meV thermal activation energy has been experimentally observed in our sample. The thermal activation is attributed as the scattering process of carriers from two-dimensional states in the vertical quantum well to the one-dimensional quantum wire states. Based on numerical energy band structure analysis, a thermal activation energy of 2-9 meV is obtained theoretically, in good agreement with the experimental data. (C) 2001 Elsevier Science B.V. All rights reserved.

We have studied the optical properties of surface quantum wells with different width of wells (5 nm and 10 nm) by in-situ photo-modulated reflectance spectroscopy on molecular beam epitaxy (MBE) system. The single surface quantum well (SQW) is confined by the vacuum on one side and by Al 0.3 Ga 0.7 As barrier on the other side. In experiments, we have observed clearly the transitions from the confined hole states to the confined electron states. The transitions between those excited states in 10 nm surface quantum well are observed for the first time. The effects of the surface on the confined states have been well studied by combination of the PR spectra and the effective mass approximation theory.

We report a theoretical investigation of the strain effects on the electronic energy band in a ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}\ensuremath{-}\mathrm{I}\mathrm{n}}_{0.25}{\mathrm{Ga}}_{0.75}{\mathrm{A}\mathrm{s}\ensuremath{-}\mathrm{A}\mathrm{l}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{As}$ asymmetric quantum wire formed in a V-grooved substrate. Our model is based on the ${\mathrm{sp}}^{3}{s}^{*}$ tight-binding model. It includes different spatial distributions of the lattice-mismatch-induced strain. We solve numerically the tight-binding Hamiltonian through the local Green's function from which the electronic local density of states (LDOS) is obtained. The detailed energy band structure (discrete localized states and energy bands of extended states) and the spatial distribution of the eigenfunctions (wave function amplitude of nondegenerate states or sum of the wave function amplitudes of degenerate states) are directly reflected in the LDOS. Spatial mapping of the LDOS's shows a reduction of the lowest excitation energies in different regions of the system when the local lattice structure of the ${\mathrm{In}}_{0.25}{\mathrm{Ga}}_{0.75}\mathrm{As}$ layer relaxes from completely strained to completely relaxed. By comparing the calculated results with photoluminescence measurement data, we conclude that the strain in the ${\mathrm{In}}_{0.25}{\mathrm{Ga}}_{0.75}\mathrm{As}$ layer relaxes linearly from the heterointerface with the ${\mathrm{Al}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{As}$ buffer layer to the heterointerface with the top GaAs layer.

National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science,Shanghai 200083, China~Received 11 February 1999!Persistent currents and charge stiffness in one-dimensional~1D! correlated disordered rings are investigatedby a transfer-matrix method. It is found that, under certain conditions the electronic states do not feel theexistence of the disorder and the ring recovers the ordered case. If the occupied energy is just at the unscatteredstate energy level, the persistent current is not reduced and shows the behavior of sudden jumps regardless ofthe disorder, contrary to the general theorem where the current is obviously reduced and becomes a smoothfunction of flux, passing through zero. For other occupied energy, the persistent current is scattered anddecreased as expected. The results indicate that a quantum interference effect can be observed in 1D correlateddisordered rings. Further, the results provide evidence that the realization of delocalized states in the experi-ments is easily obtained by observing only the persistent current of finite length rings, in contrast to the 1Ddisordered chain where the infinite length is needed.I. INTRODUCTION

The mesoporous framework of MCM-41 is found in this study to be remarkably stabilized in boiling water for 1 week by simply substituting structural Al in the framework or introducing non-structural Al species onto the pore surface of MCM-41. The enhancement of the stability of MCM-41 is found to be attributed to two major factors: The effect of randomness in pore structure (due to structural Al species in the framework) in enhancing the thermodynamic stability of the mesostructural framework as well as the effect of the “protective surface composite layer” (due to the non-structural Al-species on the pore surface) in preventing the covered surface hydroxyl groups from hydrolysis with water molecules.

The effect of Al substitution on the hydrothermal stability of Si−Al−MCM-41 (Si/Al = 50) under different treatment conditions has been investigated in detail, and a fundamental understanding is discussed based on its effect on both geometrical and chemical properties of MCM-41. Compared with Si−MCM-41, the small amount of Al substituted in the framework of Si−Al−MCM-41 is shown to give remarkable improvement of the hydrothermal stability of Si−Al−MCM-41 in boiling water for days. It is found that the existence of Al and Na species in Si−Al−MCM-41 yields less uniformly arranged pore structures than Si−MCM-41, providing a better hydrothermal stability for Si−Al−MCM-41. Both the Al in the framework and the nonstructural Al species on the surface help to protect the mesoporous structure from degradation in boiling water. In addition, the presence of TEAOH during the synthesis of Si−Al−MCM-41 may result in a better condensation of the Si−O−Si bonds, enhancing the stability of Si−Al−MCM-41 under the hydrotherma...

We report the measurement of carrier concentration and mobility of metalorganic chemical vapor deposited GaN thin films on the sapphire substrate by an infrared reflection technique. By fitting with the experimental data we obtain all the parameters of the lattice vibration oscillators and of the plasmon. From the plasmon frequency and the damping constant we have derived the carrier concentration and the electron mobility. The concentration agrees with the Hall data very well while the mobility values are smaller than that of the Hall measurement by a factor of about 0.5. We attribute such mobility lowering to the increase of scattering for the electrons coupling with the incident photons.

We investigate the delocalization-localization transition in a one-dimensional disordered system with two hybridized bands. The effects of both disorder and interband hybridization on the energy spectrum and the properties of wavefunctions are studied by using the improved Dean method and the second-moment formula. The results show that there exist band tails in the gap regions. All subbands are widened by increasing the disorder strength, whereas when the interband hybridization increases, some subbands become narrower and the others are widened. The delocalization of the wavefunctions tends to be enhanced as the hybridization increases. The localization-delocalization transition of the wavefunctions occurs when the interband hybridization becomes larger than a critical value. The competition between disorder and hybridization determines the nature of the electronic states and the energy spectrum.

We study here the dispersion relation and propagation of the interface polariton modes in specially constructed disordered GaAs/AlAs superlattices by using the transfer matrix method. The calculation of dispersion relation shows that the polariton modes exist only in two frequency regions, occur in some minibands and some isolated modes in each polariton band due to disordered effect and exhibit only small shift by varying the degree of thickness randomness, which are qualitatively in agreement with the experimental conclusions. We also find that some modes of interface polaritons with special frequencies are completely unscattered by randomness and can propagate through the structure, in contrast to the localized theory of one-dimensional (1D) disordered systems, while the other modes rapidly decay and are completely scattered. These results can be used to obtain the more realistic photonic band gaps and locations of the resonant photonic states in the 1D systems. This provides a possibility of building ...

A new two-dimensional map is proposed to investigate the nonlinear and quantum effects on the tunnelling of carriers (electrons or holes) in a novel one-dimensional semimagnetic semiconductor superlattice. The magnetic-polaron effect resulting from the exchange interaction between the carrier in a mesoscopic dot and localized magnetic-ion spins leads to a nonlinear nature of the effective Schrodinger equation for the carrier. We find gaps and different multistability in the tunnelling properties of carriers that depend critically on the wavevector of the injected carriers. In particular, when the nonlinear coefficient is increased new nontunnelling regions appear adjacent to the regular instability regions. The properties can be useful for the transmission of information in microelectronic devices.