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Three types of self-piercing riveting (SPR) joints, i.e., steel/aluminum, carbon fiber reinforced polymer (CFRP)/ aluminum, and aluminum/aluminum, were constructed using three different top sheet materials with the same aluminum alloy as the bottom sheet. The effects of the top sheet material on the joint quality and mechanical behavior were evaluated. The top sheet materials’ characteristics dominate the rivet piercing process and the consequent interlock distance. The high-strength steel top sheet requires a comparatively higher rivet setting force and induces early flaring of the rivet tail, resulting in a larger interlock distance. Though the CFRP needs the highest rivet setting force to penetrate the rivet through the CFRP fibers, the CFRP/aluminum joint exhibits the smallest interlock distance because of the SPR process-induced damages to the CFRP and subsequently less flaring of the rivet tail. In strength tests, the damaged CFRP sheet resulted in rivet head pullout of the CFRP/aluminum joints, which exhibited the lowest lap-shear and cross-tension strengths. In contrast, the steel/aluminum joints demonstrated the highest strengths because of their comparatively larger interlock distances. In addition to the experimental analysis, simulations revealed the rivet penetration and flaring mechanisms with various top sheet materials, and their respective joint quality and strengths.

Herein, a new concept of device architecture to fabricate fibrous light-emitting devices is demonstrated based on an electrochemiluminescence (ECL) material for an electronic textile system. A unique feature of this work is that instead of conventional semiconductor materials, such as organics, perovskites, and quantum dots for fibrous light emitting devices, a solid-state ECL electrolyte gel is employed as a light-emitting layer. The solid-state ECL gel is prepared from a precursor solution composed of matrix polymer, ionic liquid, and ECL luminophore. From this, we successfully realize light-emitting fibers through a simple and cost-effective single-step dip-coating method in ambient air, without complicated multistep vacuum processes. The resulting fiber devices reliably operated under applied AC bias of ±2.5 V and showed luminance of 47 cd m

DNA methylation, and consequent down-regulation, of tumour suppressor genes occurs in response to epigenetic stimuli during cancer development. Similarly, human oncoviruses, including human papillomavirus (HPV), up-regulate and augment DNA methyltransferase (DNMT) and histone deacetylase (HDAC) activities, thereby decreasing tumour suppressor genes (TSGs) expression. Ubiquitin-like containing PHD and RING finger domain 1 (UHRF1), an epigenetic regulator of DNA methylation, is overexpressed in HPV-induced cervical cancers. Here, we investigated the role of UHRF1 in cervical cancer by knocking down its expression in HeLa cells using lentiviral-encoded short hairpin (sh)RNA and performing cDNA microarrays. We detected significantly elevated expression of thioredoxin-interacting protein (TXNIP), a known TSG, in UHRF1-knockdown cells, and this gene is hypermethylated in cervical cancer tissue and cell lines, as indicated by whole-genome methylation analysis. Up-regulation of UHRF1 and decreased TXNIP were further detected in cervical cancer by western blot and immunohistochemistry and confirmed by Oncomine database analysis. Using chromatin immunoprecipitation, we identified the inverted CCAAT domain-containing UHRF1-binding site in the TXNIP promoter and demonstrated UHRF1 knockdown decreases UHRF1 promoter binding and enhances TXNIP expression through demethylation of this region. TXNIP promoter CpG methylation was further confirmed in cervical cancer tissue by pyrosequencing and methylation-specific polymerase chain reaction. Critically, down-regulation of UHRF1 by siRNA or UHRF1 antagonist (thymoquinone) induces cell cycle arrest and apoptosis, and ubiquitin-specific protease 7 (USP7), which stabilises and promotes UHRF1 function, is increased by HPV viral protein E6/E7 overexpression. These results indicate HPV might induce carcinogenesis through UHRF1-mediated TXNIP promoter methylation, thus suggesting a possible link between CpG methylation and cervical cancer.

Some necessary and sufficient conditions are found for Banach function lattices to have the Radon–Nikodým property. Consequently it is shown that an Orlicz function space L φ over a non-atomic σ -finite measure space ( Ω , Σ , μ ) , not necessarily separable, has the Radon–Nikodým property if and only if φ is an N -function at infinity and satisfies the appropriate Δ 2 condition. For an Orlicz sequence space l φ , it has the Radon–Nikodým property if and only if φ satisfies the Δ 2 0 condition. In the second part a relationship between uniformly l 1 2 points of the unit sphere of a Banach space and the diameter of the slices are studied. Using these results, a quick proof is given that an Orlicz space L φ has the Daugavet property only if φ is linear, so when L φ is isometric to L 1 . Another consequence is that Orlicz spaces equipped with the Orlicz norm generated by N -functions never have the local diameter two property, while it is well-known that when equipped with the Luxemburg norm, it may have that property. Finally, it is shown that the local diameter two property, the diameter two property, and the strong diameter two property are equivalent in Orlicz function and sequence spaces with the Luxemburg norm under appropriate conditions on φ .

Sum frequency generation imaging microscopy (SFG-IM) is a unique surface-specific technique that can detect the spatial distributions of differing monolayer species based on chemical contrast. Here...

This qualitative descriptive study was designed to identify HIV-related questions frequently asked by online counseling users seeking professional advice. Data were collected via a public online question/answer counseling website operated by the Gyeonggi-do branch of the Korean Association for AIDS Prevention. Data on users' questions regarding HIV were collected between January 1, 2017, and December 31, 2018. The online questions were then analyzed and divided into codes and categories. From the 559 questions submitted, content analysis identified four major categories related to HIV: (a) HIV testing, (b) self-perceived HIV risk and risky sexual behaviors, (c) positive and negative emotional states, and (d) treatment and prevention. This study indicates that online counseling can be used to provide tailored information related to HIV along with emotional and psychosocial support to reach different subgroups and to provide current information such as the use of pre-exposure prophylaxis for those seeking professional advice.

Epitaxial growth of one-dimensional nanowires has received considerable attention for vertically aligned nanoelectronic devices; however, high integration and reproducibility are still significant ...

Persistent infection with high-risk strains of human papillomavirus (HPV) is the primary cause of cervical cancer, the fourth most common cancer among women worldwide. Two oncoproteins encoded by the HPV genome, E6 and E7, are required for epigenetic modifications that promote cervical cancer development. We found that knockdown of HPV E6/E7 by siRNA reduced the levels of ubiquitin-like containing PHD and RING finger domain 1 (UHRF1) but increased the levels of gelsolin (GSN) in early stage cervical cancer cells. In addition, we found that UHRF1 levels were increased and GSN levels were decreased in early stage cervical cancer compared with those in normal cervical tissues, as shown by Western blot analysis, immunohistochemistry, and analysis of the Oncomine database. Moreover, knockdown of UHRF1 resulted in increased cell death in cervical cancer cell lines. Treatment of E6/E7-transformed HaCaT (HEK001) cells and HeLa cells with the DNA-hypomethylating agent 5-aza-2′-deoxycytidine and the histone deacetylase inhibitor Trichostatin A increased GSN expression levels. UHRF1 knockdown in HEK001 cells by siRNA or the UHRF1 antagonist thymoquinone increased GSN levels, induced cell cycle arrest and apoptosis, and increased the levels of p27 and cleaved PARP. Those results indicate that upregulation of UHRF1 by HPV E6/E7 causes GSN silencing and a reduction of cell death in early stage cervical cancer, suggesting that GSN might be a useful therapeutic target in early stage cervical cancer.

This article examines the interfacial properties of phase-incompatible self-assembled monolayer (SAM) films derived from the adsorption of mixtures of bidentate alkanedithiols terminated with oligo...

Here, we present a strategy for the realization of p-channel inorganic thin film transistors (TFTs) based on vertically stacked contacts and a copper(I) thiocyanate (CuSCN) semiconductor. The CuSCN semiconductor was generated by a simple low-temperature (ca. 100 °C) solution-based process. Utilizing the vertical architecture, channel length was determined by the thickness of the CuSCN film. This readily endows transistors with ultrashort channel lengths (

Recently, copper iodide (CuI) has been considered as a promising inorganic p-type semiconductor material. Although significant progress using CuI has been made in materials and device applications for solar cells and thin-film transistors (TFTs), little consideration has been given to the vacancy formation mechanisms and their effect on the device performance. In this work, high performance electrolyte-gated TFTs were fabricated using CuI semiconductors with different vacancy states and the origin of the threshold voltage (Vth) shift of devices in terms of vacancy species and concentration were studied. The CuI films were fabricated via a simple solution process followed by thermal annealing at low temperature (55 °C). The vacancy species and concentration in the CuI semiconductor were regulated by changing the annealing conditions as well as by introducing a dopant material. Photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) analysis were conducted to demonstrate the correlation between the electrical properties of TFTs and the vacancy states in the CuI specimens. The CuI-TFTs exhibited typical enhancement mode operation of the p-channel transistor, with sub-1 V operation voltage, ON/OFF ratio of ∼103, and high hole mobility in the range of 10–60 cm2 V−1 s−1. Experimental results revealed that Cu vacancy (VCu) play the role of inducing hole carriers, hence, TFT with VCu-rich CuI exhibited increased carrier concentration and positively shifted Vth of 0.14 V. However, iodine vacancy (VI) in CuI captures hole carriers, decreasing the concentration of charge carriers (holes), resulting to a negative Vth of −0.19 V. The TFT mobility was also affected by the vacancy concentration, owing to the carrier scattering effect. For instance, the I-rich (or VCu-rich) CuI exhibited decreased TFT mobility (14.70 cm2 V−1 s−1) due to the high carrier concentration (1019 cm−3) and their scattering effect.

We study the denseness of Crawford number attaining operators on Banach spaces. Mainly, we prove that if a Banach space has the RNP, then the set of Crawford number attaining operators is dense in the space of bounded linear operators. We also see among others that the set of Crawford number attaining operators may be dense in the space of all bounded linear operators while they do not coincide, by observing the case of compact operators when the Banach space has a 1-unconditional basis. Furthermore, we show a Bishop-Phelps-Bollob\'as type property for the Crawford number for certain Banach spaces, and we finally discuss some difficulties and possible problems on the topic., Comment: 15 pages

We introduce a vector-valued version of a uniform algebra, called the vector-valued function space over a uniform algebra. The diameter two properties of the vector-valued function space over a uniform algebra on an infinite compact Hausdorff space are investigated. Every nonempty relatively weakly open subset of the unit ball of a vector-valued function space $$A(K, (X, \tau ))$$ over an infinite dimensional uniform algebra has diameter two, where $$\tau $$ is a locally convex Hausdorff topology on a Banach space X compatible to a dual pair. Under the assumption of X equipped with the norm topology being uniformly convex and the additional condition that $$A\otimes X\subset A(K, X)$$ , it is shown that Daugavet points and $$\Delta $$ -points on A(K, X) over a uniform algebra A are the same, and they are characterized by the norm-attainment at a limit point of the Shilov boundary of A. In addition, a sufficient condition for the convex diametral local diameter two property of A(K, X) is also provided. Similar results also hold for an infinite dimensional uniform algebra.

The antifouling properties of self-assembled monolayers (SAMs) on gold generated from custom-designed bidentate unsymmetrical spiroalkanedithiols containing both oligo(ethylene glycol) and hydrocarbon tailgroups (EG3C7-C7 and EG3C7-C18) were evaluated and compared to SAMs derived from analogous monodentate octadecanethiol (C18SH) and the tri(ethylene glycol)-terminated alkanethiol EG3C7SH. Complementary techniques, including in situ surface plasmon resonance spectroscopy (SPR), ex situ electrochemical quartz crystal microbalance (QCM) measurements, and ex situ ellipsometric thickness measurements, were employed to assess the protein resistance of the SAMs using proteins having a wide range of sizes, structures, and properties: protamine, lysozyme, bovine serum albumin (BSA), and fibrinogen. The studies found that SAMs generated from the bidentate adsorbates EG3C7-C7 and EG3C7-C18, which contain a 1:1 mixture of OEG and hydrocarbon tailgroups, exhibited a diminished capacity to resist protein adsorption compared to the EG3C7SH SAMs, which possess only OEG tailgroups. The data highlight the critical role of hydration of the OEG matrix for generating antifouling OEG-based surface coatings.

New ether-substituted poly(1,4-phenylene vinylene) (PPV) derivatives were synthesized via Horner–Emmons coupling. The structures of the monomers and the resultant oligomers were confirmed by 1H and 13C NMR spectroscopies. The molecular weights of the oligomers were characterized by gel permeation chromatography, giving the number-average and weight-average molecular weights and the corresponding polydispersity indices. Measurements of UV–vis absorption and fluorescence were used to characterize the optical properties of the oligomers. Estimation of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels and other electrochemical characteristics of the oligomers were investigated by cyclic voltammetry. Dialkyl and dialkoxy PPV oligomers were also prepared and characterized following the same instrumental methods used for the ether-substituted oligomers, providing a known reference system to judge the performance of the new conjugated oligomers. Devices were fabricated to analyze the electroluminescent characteristics of the oligomers in organic light-emitting diodes.

We study the Birkhoff-James orthogonality on operator spaces in terms of the Bhatia-Semrl property. We first prove that every functional on a Banach space X has the Bhatia-Semrl property if and only if X is reflexive. We also find some geometric conditions of Banach space which ensure the denseness of operators with Bhatia-Semrl property. Finally, we investigate operators with the Bhatia-Semrl property when a domain space is L 1 [ 0 , 1 ] or C [ 0 , 1 ] .

Sum frequency generation (SFG) images of microcontact patterned self-assembled alkanethiol monolayers on metal surfaces were analyzed by factor analysis (FA) to determine the spatial distribution of the patterned monolayers over the images. Additionally, each significant abstract factor produced by FA was assessed to determine the information contained within it. These results indicate that FA of the SFG spectra is a promising method to determine the composition and identities of mixed alkanethiol systems that show different vibrational spectra and image contrast. Factor analysis has successfully been applied to SFG images obtained with low signals, which reduces the time required for full spectral SFG imaging.

While molecular-level structural information is readily available for n-alkanethiol self-assembled monolayers (SAMs) on noble metal surfaces, the same cannot be claimed for dithiol-based SAMs due to their lack of long-range-order. This work provides molecular-level structural information on dithiol SAMs by investigating 5-( octyloxy)-1,3-phenylenedimethanethiol (OPDT) SAMs on Au(111) surfaces, using combined high-resolution scanning tunneling microscopy (STM), atomic force microscopy (AFM), and nanolithography. The high coverage OPDT SAMs do not exhibit long-range order. Desorption of these OPDT SAMs leads to the formation of ordered domains known as the striped phases, whose unit mesh is revealed as commensurate with the underlying Au(111) lattice. In these domains, OPDT molecules are lying-down, with the benzene ring and the zigzag plane of the alkyl chain parallel to the Au(111) surface. At the boundaries of these ordered structures, standing-up OPDT molecules are frequently present with an intermolecular space of 1 nm (i.e., 1D ordered structures). Using these ordered structures as internal standards in situ, the structure of the high-coverage OPDT SAMs is revealed: a mixture of standing-up and lying-down molecules randomly distributed on Au(111); as such, these SAMs exhibit little long-range order or ordered domains. The two thiols of each OPDT molecule occupy triple hollow sites on Au(111) surfaces. In the standing-up configuration, the benzene ring is perpendicular to the surface. In the lying-down con-figuration, the benzene ring and zigzag plane of the alkyl chain are parallel to the Au(111) surface. This work represents a high-resolution and molecular-level structural characterization of functionalized dithiol SAMs, furthering our understanding of dithiol molecule-surface interactions and the unique properties of these SAMs.

We introduce and investigate the mth polarization constant of a Banach space X for the numerical radius. We first show the difference between this constant and the original mth polarization constant associated with the norm by proving that the new constant is minimal if and only if X is strictly convex, and that there exists a Banach space which does not have an almost isometric copy of $$\ell _1^2$$ , such that the second polarization constant for the numerical radius is maximal. We also give a negative answer for complex Banach spaces to the question of Choi and Kim (J Lond Math Soc (2) 54(1):135–147, 1996) whether $$\frac{\sum _{k=1}^m k^m ~\left( {\begin{array}{c}m\\ k\end{array}}\right) }{m!}$$ is the optimal upper bound for the mth polarization constant for arbitrary $$m\in \mathbb {N}$$ . Finally, we generalize the result of Garcia et al. (Proc Am Math Soc 142(4):1229–1235, 2014) that, for 2-homogeneous polynomials, the numerical index of a complex lush space is greater or equal than 1/3.

Light-emitting transistors (LETs) have attracted a significant amount of interest as multifunctional building blocks for next-generation electronics and optoelectronic devices. However, it is challenging to obtain LETs with a high carrier mobility and uniform light-emission because the semiconductor channel should provide both the electrical charge transport and optical light-emission, and typical emissive semiconductors have low, imbalanced carrier mobilities. In this work, a novel device platform that adapts the electrochemiluminescence (ECL) principle in LETs, referred to as an ECL transistor (ECLT) is proposed. ECL is a light-emission phenomenon from electrochemically excited luminophores generated by redox reactions. A solid-state ECL electrolyte consisting of a network-forming polymer, ionic liquid, luminophore, and co-reactant is employed as the light-emitting gate insulator of the ECLT. Based on this construction, high-performance LETs that make use of various conventional non-emissive semiconductors (e.g., poly(3-hexylthiophene), zinc oxide, and reduced graphene oxide) are successfully demonstrated. All the devices exhibit a high mobility (0.9-10 cm2 V-1 s-1 ) and a uniform light-emission. This innovative approach demonstrates a novel LET platform and provides a promising pathway to achieve significant breakthroughs to develop electronic circuits and optoelectronic applications.

In this paper, we are interested in studying two properties related to the denseness of the operators which attain their numerical radius: the Bishop-Phelps-Bollob\'as point and operator properties for numerical radius (BPBpp-nu and BPBop-nu, respectively). We prove that every Banach space with micro-transitive norm and second numerical index strictly positive satisfy the BPBpp-nu and that, if the numerical index of $X$ is 1, only one-dimensional spaces enjoy it. On the other hand, we show that the BPBop-nu is a very restrictive property: under some general assumptions, it holds only for one-dimensional spaces. We also consider two weaker properties, the local versions of BPBpp-nu and BPBop-nu, where the $\eta$ which appears in their definition does not depend just on $\epsilon > 0$ but also on a state $(x, x^*)$ or on a numerical radius one operator $T$. We address the relation between the local BPBpp-nu and the strong subdifferentiability of the norm of the space $X$. We show that finite dimensional spaces and $c_0$ are examples of Banach spaces satisfying the local BPBpp-nu, and we exhibit an example of a Banach space with strongly subdifferentiable norm failing it. We finish the paper by showing that finite dimensional spaces satisfy the local BPBop-nu and that, if $X$ has strictly positive numerical index and has the approximation property, this property is equivalent to finite dimensionality.

We study approximation of operators between Banach spaces $X$ and $Y$ that nearly attain their norms in a given point by operators that attain their norms at the same point. When such approximations exist, we say that the pair $(X, Y)$ has the pointwise Bishop-Phelps-Bollob\'as property (pointwise BPB property for short). In this paper we mostly concentrate on those $X$, called universal pointwise BPB domain spaces, such that $(X, Y)$ possesses pointwise BPB property for every $Y$, and on those $Y$, called universal pointwise BPB range spaces, such that $(X, Y)$ enjoys pointwise BPB property for every uniformly smooth $X$. We show that every universal pointwise BPB domain space is uniformly convex and that $L_p(\mu)$ spaces fail to have this property when $p>2$. For universal pointwise BPB range space, we show that every simultaneously uniformly convex and uniformly smooth Banach space fails it if its dimension is greater than one. We also discuss a version of the pointwise BPB property for compact operators., Comment: 19 pages, to appear in the Canadian J. Math. In this version, section 6 and the appendix of the previous version have been removed

Titanium dioxide (TiO 2 ) has gained increasing interest in materials research due to its outstanding properties and promising applications in a wide range of fields. From this perspective, we report the synthesis of custom-designed anatase TiO 2 submicrometer particles coated with partial Au shells (ATiO 2 -AuShl). The synthetic strategy used herein yields uniformly shaped monodisperse particles. Amorphous TiO 2 core particles were synthesized using template-free oxidation and hydrolysis of titanium nitride (TiN); subsequent hydrothermal treatment generated anatase TiO 2 (ATiO 2 ) particles. Coating ATiO 2 particles with partial Au shells was accomplished using a simple seeded-growth method. Evaluation of the optical properties of these ATiO 2 -AuShl particles showed that these submicrometer composites exhibited an intense absorption peak for TiO 2 in the UV region (∼326 nm) and a broad extinction band in the visible range (∼650 nm) arising from the incomplete Au shell. These ATiO 2 -AuShl composite particles provide a unique and effective means for broadening the optical response of TiO 2 -based nano- and micron-scale materials. The simplicity of our synthetic method should broaden the application of ATiO 2 -AuShl particles in various visible light-driven technologies.

Surface dipoles are a powerful tool in interfacial modification for improving device output via energy level matching. Fluorinated alkanethiols show a strong promise for these applications as they ...

Recently, metallic particulate pollutants floating underground have been reported to negatively affect the human body. Thus, there is an urgent need for a public health policy pertaining to the air quality in subway stations. In this study, we investigated whether a vegetation biofilter is effective in reducing metal particle contaminants, especially iron oxide. After selecting a subway station, a vegetation biofilter system was installed, and samples were collected three times, at three intake areas and one exhaust area. The average weight ratio of the detected elements was calculated. The iron oxide reduction effect was evaluated using the Wilcoxon signed rank test. In the return air, C, O, and Fe were detected at 64.9, 27.3, and 5.2 wt.%, respectively, in the supply air, C, O, and Fe were detected at 67.2, 30.4, and 0.7 wt.%, respectively. The difference in the average Fe weight ratio was statistically significant. Air quality has a considerable effect on human health. We confirmed the possibility of reducing Fe in particulate matter using biofilters. However, we could not confirm whether the air quality was improved enough to not have a negative effect on the human body. This should be elucidated through follow-up studies.

Spherical diffusion flames of gaseous fuels supported on a porous spherical burner are investigated experimentally in microgravity for long durations aboard the International Space Station (ISS). Experimental results are compared with a transient numerical model. The experiments involve normal spherical diffusion flames (i.e., fuel flowing into oxidizer) burning ethylene in an oxygen/nitrogen mixture at atmospheric pressure. The stoichiometric mixture fraction and adiabatic flame temperature are varied by diluting the fuel with nitrogen and varying the oxygen concentration in the ambient. The diagnostics consist of color video, thin-filament pyrometry for gas temperature, thermocouple measurements of burner temperature, and photomultiplier tube measurements of broad and narrow-band flame emission. Burn times range from 28 – 336 s. All flames grow monotonically after ignition. Peak gas temperature generally decreases with time. Radiative extinction is observed when, at constant reactant flow rate, the flame expands until radiation heat loss approaches the chemical heat release. Before a flame experiences complete extinction, it may enter an oscillatory mode in which part of the flame partially extinguishes and then reforms. The oscillations grow in magnitude until complete extinction. Sufficiently small flames with low radiation losses exhibit quasi-steady behavior, but burner heating is significant, and the experimental duration is dictated by the temperature limit of the porous sphere.

We study the Bishop–Phelps–Bollobas property and the Bishop–Phelps–Bollobas property for numerical radius. Our main aim is to extend some known results about norm or numerical radius attaining operators to multilinear and polynomial cases. We characterize the pair ( l 1 ( X ) , Y ) to have the BPBp for bilinear forms and prove that on L 1 ( μ ) the numerical radius and the norm of a multilinear mapping are the same. We also show that L 1 ( μ ) fails the BPBp-nu for multilinear mappings although L 1 ( μ ) satisfies it in the operator case for every measure μ.

The development of p-channel devices with comparable electrical performances to their n-channel counterparts has been delayed due to the lack of p-type semiconductor materials and device optimization. In this present work, we successfully demonstrated p-channel inorganic thin-film transistors (TFTs) with high hole mobilities similar to the values of n-channel devices. To boost the device performance, the solution-processed copper iodide (CuI) semiconductor was gated by a solid polymer electrolyte. The electrolyte gating could realize electrical double layer (EDL) formation and a three-dimensional carrier transport channel and thus substantially increased charge accumulation in the channel region and realized a high mobility above 90 cm

Some local versions of the Bishop–Phelps–Bollobás property for operators have been recently presented in Dantas et al. (J Math Anal Appl 468(1):304–323, 2018). In the present article, we continue studying these properties for multilinear mappings. We show some differences between the local and uniform versions of these and also provide some interesting examples which show that this study is not just a mere generalization of the linear case. As a consequence of our results, we get that, for 2 < p, q< ∞, the norm of the projective tensor product ℓp⊗ ^ πℓq is strongly subdifferentiable. Moreover, we present necessary and sufficient conditions for the norm of a Banach space Y to be strongly subdifferentiable through the study of these properties for bilinear mappings on ℓ1N×Y. Fil: Dantas, Sheldon. Czech Technical University in Prague; República Checa Fil: Kim, Sun Kwang. Chungbuk National University; Corea del Sur Fil: Lee, Han Ju. Dongguk University, Seoul; Corea del Sur Fil: Mazzitelli, Martin Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Cuyo; Argentina. Comisión Nacional de Energía Atómica. Fundación José A. Balseiro; Argentina

In this article, we study a version of the Bishop–Phelps–Bollobas property. We investigate a pair of Banach spaces ( X , Y ) such that every operator from X into Y is approximated by operators which attain their norm at the same point where the original operator almost attains its norm. In this case, we say that such a pair has the Bishop–Phelps–Bollobas point property (BPBpp). We characterize uniform smoothness in terms of BPBpp and we give some examples of pairs ( X , Y ) which have and fail this property. Some stability results are obtained about l 1 and l ∞ sums of Banach spaces and we also study this property for bilinear mappings.