Photoluminescence Path Bifurcations by Spin Flip in Two-Dimensional CrPS₄

Ultrathin layered crystals of coordinated chromium(III) are promising not only as two-dimensional (2D) magnets but also as 2D near-infrared (NIR) emitters due to long-range spin correlation and efficient transition between high- and low-spin excited states of Cr3+ ions. In this study, we report on the dual-band NIR photoluminescence (PL) of CrPS4 and show that its excitonic emission bifurcates into fluorescence and phosphorescence depending on thickness, temperature, and defect density. In addition to the spectral branching, the biexponential decay of PL transients, also affected by the three factors, could be well described within a three-level kinetic model for Cr(III). In essence, the PL bifurcations are governed by activated reverse intersystem crossing from the low- to high-spin states, and the transition barrier becomes lower for thinner 2D samples because of surface-localized defects. Our findings can be generalized to 2D solids of coordinated metals and will be valuable in realizing groundbreaking magneto-optic functions and devices

Additional file 2: Table S1. of Ethylene induces combinatorial effects of histone H3 acetylation in gene expression in Arabidopsis

Primers for ChIP-qPCR and qPCR. Table S2. list of genome wide genes with differential histone markers in seedlings treated with air. Table S3. list of genome wide genes with differential histone markers in seedlings treated with ethylene. Table S4. list of ethylene regulated genes with differential histone markers in seedlings treated with air. Table S5. List of ethylene regulated genes with differential histone markers in seedlings treated with ethylene. (ZIP 1241 kb

Probing Local Strain at MX₂–Metal Boundaries with Surface Plasmon-Enhanced Raman Scattering

Interactions between metal and atomically thin two-dimensional (2D) materials can exhibit interesting physical behaviors that are of both fundamental interests and technological importance. In addition to forming a metal–semiconductor Schottky junction that is critical for electrical transport, metal deposited on 2D layered materials can also generate a local mechanical strain. We investigate the local strain at the boundaries between metal (Ag, Au) nanoparticles and MX₂ (M = Mo, W; X = S) layers by exploiting the strong local field enhancement at the boundary in surface plasmon-enhanced Raman scattering (SERS). We show that the local mechanical strain splits both the in-plane vibration mode E_2g¹ and the out-of-plane vibration mode A_1g in monolayer MoS₂, and activates the in-plane mode E_1g that is normally forbidden in backscattering Raman process. In comparison, the effects of mechanical strain in thicker MoS₂ layers are significantly weaker. We also observe that photoluminescence from the indirect bandgap transition (when the number of layers is ≥2) is quenched with the metal deposition, while a softened and broadened shoulder peak emerges close to the original direct-bandgap transition because of the mechanical strain. The strain at metal–MX₂ boundaries, which locally modifies the electronic and phonon structures of MX₂, can have important effects on electrical transport through the metal–MX₂ contact

Electrical Control of Optical Plasmon Resonance with Graphene

Surface plasmon has the unique capability to concentrate light into subwavelength volume.− Active plasmon devices using electrostatic gating can enable flexible control of the plasmon excitations, which has been demonstrated recently in terahertz plasmonic structures.− Controlling plasmon resonance at optical frequencies, however, remains a significant challenge because gate-induced free electrons have very weak responses at optical frequencies. Here we achieve efficient control of near-infrared plasmon resonance in a hybrid graphene-gold nanorod system. Exploiting the uniquely strong, and gate-tunable optical transitions, of graphene, we are able to significantly modulate both the resonance frequency and quality factor of gold nanorod plasmon. Our analysis shows that the plasmon–graphene coupling is remarkably strong: even a single electron in graphene at the plasmonic hotspot could have an observable effect on plasmon scattering intensity. Such hybrid graphene–nanometallic structure provides a powerful way for electrical control of plasmon resonances at optical frequencies and could enable novel plasmonic sensing down to single charge transfer events

Network modeling of the cholesterol-responsive genes.

<p>(<b>A</b>) <b>A provisional network was generated from integration of two microarray data sets.</b> Node color represents increases (red), no significant changes (yellow), and decreases (green) in gene expression in murine prostate tissue after cholesterol alteration as ascertained by cDNA microarray. Changes in RNA expression levels of the corresponding nodes in LNCaP cells are shown as colored node boundaries (donut shape) and the color represents increases (red), no significant change (yellow), and decreases (green) in gene expression under CDM conditions compared to control. Arrows indicate direct activation, T-shaped lines direct repression, dashed arrows indirect activation, and lines physical interaction. (<b>B</b>) <b>Gene expression under Normo and Hyper conditions (</b><b><i>in vivo</i></b><b>).</b> To verify <i>in vivo</i> microarray data obtained from SCID experiments, mRNA levels of the indicated genes were determined. GAPDH expression was used to normalize gene expression. Error bars represent SD (n = 3). (<b>C</b>) <b>Gene expression under Control and Cholesterol-depleted conditions (</b><b><i>in vitro</i></b><b>).</b> LNCaP cells were incubated in CDM for 0, 3 or 16 h, and mRNA levels of the indicated genes were measured by RT-PCR analysis to validate cDNA microarray data. Error bars represent SD (n = 3). *<i>p</i><0.05 (Student’s t-test).</p

Effect of dietary cholesterol on circulating and prostatic tissue cholesterol levels <i>in vivo</i>.

<p>Male SCID mice were fed for 4 months (m) either a Hyper or a Normo diet, and circulating as well as prostatic tissue cholesterol levels determined. (<b>A</b>) Hyper diet enhances prostatic proliferation. 10 randomly selected sections per group were used for analysis with proliferating cells determined by Ki-67 staining. Ki-67 positivity is shown as average ± SD (n = 10/group) of positive cells in a total of 5000 prostate epithelial cells. (<b>B</b>) <b>Circulating cholesterol levels.</b> Serum cholesterol levels were determined and are plotted as cholesterol (mg/dL) vs. diet group ± SD (n = 15/group) (<b>C</b>) <b>Cholesterol levels of prostate membrane.</b> Cholesterol was extracted from membrane fractions prepared from prostate tissue and cholesterol levels determined by Infinity assay. Data are presented as cholesterol (mg/mg tissue) vs. group ± SD (n = 3/group). *<i>p</i><0.05 (Student’s t-test).</p

Hypocholesterolemia suppresses prostatic inflammation.

<p>(<b>A</b>) <b>Proliferative index.</b> Proliferating cells were counted by Ki-67 staining as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039448#s2" target="_blank">Materials and Methods</a>. Data are plotted as Ki-67 positive cells vs. condition. (<b>B</b>) <b>Inflammation score.</b> Infiltrating cells were scored as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039448#s2" target="_blank">Materials and Methods</a>. Data are plotted as inflammation score vs. condition. (<b>C-</b><b><i>i</i></b>) <b>VP lobes from male C57BL/6 mice in the Hyper condition.</b> Lymphoid cell populations (L) infiltrating periprostatic adipose tissue adjacent to nerves (N) and blood vessels were observed in the Hyper condition (yellow arrows). Two representative fields are shown. (<b>C-</b><b><i>ii</i></b>) IHC staining with anti-CD45 (1∶150) and anti-CD3 (1∶200) show inflammatory infiltrates observed in the Hyper condition are a mixture of B and T cells. Spleen tissue from male C57BL/6 mice was used as a positive control for IHC and protocol optimization. Blue arrowhead, adipose tissue; Red arrowhead, a prostatic acinus.</p

ATF3 expression coincides with reduced cholesterol.

<p>(<b>A</b>) <b>RT-PCR analysis </b><b><i>in vivo</i></b><b>.</b> ATF3 levels are reduced in all prostatic lobes from Hyper mice, compared to those from the Normo group (AP = anterior prostate; VP = ventral prostate; DLP = dorsal prostate). (<b>B</b>) <b>Immunoblot analysis.</b> Immunoblot of PrEC lysates showed induction of ATF3 protein by CDM (left panel) and by β-cyclodextrin (right panel). MG132, a proteasome inhibitor, also increased ATF3 expression. (<b>C</b>) <b>Immunofluorescence analysis.</b> Induction of ATF3 protein by CDM in LNCaP cells as shown by IF. LNCaP cells were treated with CDM for 18 h, stained with anti-ATF3 antibody and nuclei were counterstained with DAPI (left panel: ATF3; middle panel: DAPI; right panel: overlay). (<b>D</b>) <b>RT-PCR analysis.</b> ATF3 mRNA levels in LNCaP cells treated with CDM were normalized to levels of GAPDH. RT-PCR analysis shows induction of ATF3 mRNA levels by CDM. (<b>E–F</b>) <b>Promoter </b><b>reporter analysis.</b> A full-length ATF3 promoter was cloned into a luciferase reporter vector and transfected into LNCaP (D) or PrEC (E). Cells were then incubated in Control and CDM medium. ATF3 promoter activity was plotted as arbitrary units (± SD) after normalization with total protein concentration.</p

ATF3 expression level is associated with cholesterol level <i>in vivo</i>.

<p>Male C57BL/6 mice were fed Hypo, Normo, or Hyper diets for 4 months. (<b>A</b>) <b>Circulating cholesterol levels.</b> Serum cholesterol levels are plotted as cholesterol (mg/dL) vs. diet group ± SD (n = 18/group). (<b>B</b>) <b>RT-PCR analyses of ATF3 expression.</b> The expression levels of ATF3 mRNA and protein were compared in ventral prostate (VP) from male C57BL/6 mice in Hypo, Normo or Hyper conditions by quantitative densitometry. Data are plotted as mRNA level (arbitrary unit) vs. condition ± SD (n = 3). GAPDH expression was used to normalize gene expression. (<b>C</b>) <b>Immunohistochemical analysis of ATF3 expression.</b> Sections of VP tissues from mice in Hypo, Normo or Hyper groups, stained with anti-ATF3 antibody. Representative images of Hypo and Hyper are shown. (<b>D</b>) <b>Immunoblot analyses of ATF3</b>. Immunoblot data are presented as box and whisker plots of ATF3 expression levels (arbitrary units) vs. group. Bottom of red = median of lower half of the data. Top of yellow = median of upper half of the data. Intersection of red and yellow = median. Green = average. Vertical bars extend to maxima and minima (n =  18/group). *<i>p</i><0.05 (two way ANOVA and Student’s t-test). Representative western blot data are shown (right).</p

ATF3 is a negative regulator of cyclin D1 and cell proliferation.

<p>(<b>A</b>) <b>Enforced AFT3 expression reduces cell proliferation.</b> LNCaP cells were transiently transfected with an ATF3 expression construct, a vector alone control, or with the AFT3 expression construct + ATF3 siRNAs. Proliferation rate was measured at the indicated times. ATF3 expression levels were verified by immunoblot (upper panels). Data are plotted as cell proliferation (fold) vs. condition (Vec, ATF3, ATF3+siATF3) ± SD (n = 3). (<b>B–C</b>) <b>Knockdown of ATF3 increases cell proliferation.</b> LNCaP cells were transiently transfected with siATF3 (or siCon) and the number of cells at day 0 (grey bars) & day 3 (black bars) were measured. Four independent ATF3 siRNAs (siATF3-1, -2, -3, and -4) were transiently transfected, and cell numbers were determined at day 3. Data are plotted as cell proliferation (fold) vs. condition ± SD (n = 3). (<b>D</b>) <b>Effect of cholesterol depletion on ATF3 and cyclin D1 expression.</b> LNCaP cell were treated in serum free media (SF; grey bars) or with CDM (black bars) for 16 h and the level of ATF3 and cyclin D1 were determined. Data were normalized to β-actin from the same blots. Immunoblot data are representative of the immunoblot result used in densitometry. Data are plotted as expression level (fold) vs. condition ± SD (n = 3). (<b>E</b>) <b>ATF3 regulates cholesterol depletion-induced cyclin D1 expression (immunoblot analysis).</b> LNCaP cells were transiently transfected with siATF3 (or siCon). After serum starvation for 16 h, cells were stimulated with 10% serum for the indicated times. Immunoblot analysis was performed to determine cyclin D1 expression in ATF3 deficient cells. (<b>F</b>) <b>ATF3 regulates cyclin D1 expression (promoter reporter analysis).</b> LNCaP cells were transfected with promoter construct of cyclin D1 containing a luciferase reporter and followed by additional incubation with ± serum for 6 h. Data are plotted as promoter activation (fold) vs. condition ± SD (n = 3). (<b>G</b>) <b>Promoter activation of cyclin D1 upon cholesterol alteration requires ATF3 binding on promoter region (promoter reporter analysis).</b> LNCaP cells were transfected with a luciferase construct of a wild type (WT) or an ATF3 binding site mutated cyclin D1 (MUT) promoter. Promoter activity was measured 6 h after treatment with various conditions (±FBS or CDM). Data are plotted as promoter activation (fold) vs. condition ± SD (n = 4). All experiments were performed a minimum of 3 times. *<i>p</i><0.05, **<i>p</i><0.01 (Student’s t-test).</p