Surface-Engineered Nanomaterials for Optical Array Based Sensing

Array based sensing governed by optical methods provides fast and economic way for detection of wide variety of analytes where the ideality of detection processes depends on the sensor element's versatile mode of interaction with multiple analytes in an unbiased manner. This can be achieved by either the receptor unit having multiple recognition moiety, or their surface property should possess tuning ability upon fabrication called surface engineering. Nanomaterials have a high surface to volume ratio, making them viable candidates for molecule recognition through surface adsorption phenomena, which makes it ideal to meet the above requirements. Most crucially, by engineering a nanomaterial's surface, one may produce cross-reactive responses for a variety of analytes while focusing solely on a single nanomaterial. Depending on the nature of receptor elements, in the last decade the array-based sensing has been considering as multimodal detection platform which operates through various pathway including single channel, multichannel, binding and indicator displacement assay, sequential ON-OFF sensing, enzyme amplified and nanozyme based sensing etc. In this review we will deliver the working principle for Array-based sensing by using various nanomaterials like nanoparticles, nanosheets, nanodots and self-assembled nanomaterials and their surface functionality for suitable molecular recognition.

First Measurement of the Michel Parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} Decay at Belle

We report the first measurement of the Michel parameter ξ^{'} in the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} events with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988  fb^{-1} collected by the Belle detector corresponds to approximately 912×10^{6} τ^{+}τ^{-} pairs. We measure ξ^{'}=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ξ^{'}=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.

Search for the Lepton Flavor Violating Decays B^{+}→K^{+}τ^{±}ℓ^{∓} (ℓ=e, μ) at Belle

We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,μ), using the full data sample of 772×10^{6}  BB[over ¯] pairs recorded by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range. The obtained limits are the world's best results.

First Measurement of the B^{+}→π^{+}π^{0}π^{0} Branching Fraction and CP Asymmetry

We study B^{+}→π^{+}π^{0}π^{0} using 711  fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10^{-6} and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B^{+}→ρ(770)^{+}π^{0} branching fraction of (11.2±1.1±0.9_{-1.6}^{+0.8})×10^{-6}, where the third uncertainty is due to possible interference with B^{+}→ρ(1450)^{+}π^{0}. We present the first observation of a structure around 1  GeV/c^{2} in the π^{0}π^{0} mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9±0.9±0.6)×10^{-6}. We also report a measurement of local CP asymmetry in this structure.

First Observation of Λπ^{+} and Λπ^{-} Signals near the K[over ¯]N(I=1) Mass Threshold in Λ_{c}^{+}→Λπ^{+}π^{+}π^{-} Decay

Using the data sample of 980  fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}→Λπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.3±0.6(stat)±0.9(syst)  MeV/c^{2} [1438.5±0.9(stat)±2.5(syst)  MeV/c^{2}], an intrinsic width of 11.5±2.8(stat)±5.3(syst)  MeV/c^{2} [33.0±7.5(stat)±23.6(syst)  MeV/c^{2}] with a significance of 7.5σ (6.2σ). As these two signals are very close to the K[over ¯]N threshold, we also investigate the possibility of a K[over ¯]N cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.

Evidence of a New Excited Charmed Baryon Decaying to Σ_{c}(2455)^{0,++}π^{±}

We present the study of B[over ¯]^{0}→Σ_{c}(2455)^{0,++}π^{±}p[over ¯] decays based on 772×10^{6}  BB[over ¯] events collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The Σ_{c}(2455)^{0,++} candidates are reconstructed via their decay to Λ_{c}^{+}π^{∓} and Λ_{c}^{+} decays to pK^{-}π^{+}, pK_{S}^{0}, and Λπ^{+} final states. The corresponding branching fractions are measured to be B(B[over ¯]^{0}→Σ_{c}(2455)^{0}π^{+}p[over ¯])=(1.09±0.06±0.07)×10^{-4} and B(B[over ¯]^{0}→Σ_{c}(2455)^{++}π^{-}p[over ¯])=(1.84±0.11±0.12)×10^{-4}, which are consistent with the world average values with improved precision. A new structure is found in the M_{Σ_{c}(2455)^{0,++}π^{±}} spectrum with a significance of 4.2σ including systematic uncertainty. The structure is possibly an excited Λ_{c}^{+} and is tentatively named Λ_{c}(2910)^{+}. Its mass and width are measured to be (2913.8±5.6±3.8)  MeV/c^{2} and (51.8±20.0±18.8)  MeV, respectively. The products of branching fractions for the Λ_{c}(2910)^{+} are measured to be B(B[over ¯]^{0}→Λ_{c}(2910)^{+}p[over ¯])×B(Λ_{c}(2910)^{+}→Σ_{c}(2455)^{0}π^{+})=(9.5±3.6±1.6)×10^{-6} and B(B[over ¯]^{0}→Λ_{c}(2910)^{+}p[over ¯])×B(Λ_{c}(2910)^{+}→Σ_{c}(2455)^{++}π^{-})=(1.24±0.35±0.10)×10^{-5}. Here, the first and second uncertainties are statistical and systematic, respectively.

Time resolved fluorescence sensor array for discrimination of phosphate anions by using transition metal dichalcogenide quantum dots and Tb (III)

Phosphate detection has garnered widespread attention due to their biological and environmental impact. Among several optical techniques, time resolved fluorescence (TRF) provides a sensitive way for discrimination of analytes in a complex mixture as it suffers less interference from the background, thus providing a high signal to noise ratio. The sensitization of rare earth metal (REM) ions by semiconducting quantum dots (QDs) can help the former overcome the drawback of low absorption coefficient, thus allowing one to exploit the additional advantage of the REM, viz, the long-excited state lifetime. Herein, we have developed a TRF based sensor array consisting of three QDs, i.e., MoS₂ , WS₂ and MoSe₂ as energy sensitizers to Tb³⁺ ion. Different QDs possess variable energy transfer ability to Tb³⁺ ion. Hence, they can be used for discrimination of phosphates. It was also observed that CrO₄ ^2- can competitively bind to Tb³⁺ and further, enhance the efficiency of the sensor array which could discriminate six different phosphates at 200 μM concentration in aqueous as well as serum media with a detection limit of 10 μM in aqueous media. Thus, the sensitivity of the TRF based sensor array is rarely compromised in a complex mixture, which is advantageous over a fluorescence-based sensor array.

Ligand Exchange on MoS2 Nanosheets: Applications in Array-Based Sensing and Drug Delivery

Two-dimensional MoS2 nanosheets (2D-MoS2) have been widely used in many biological applications due to their distinctive physicochemical properties. Further, the development of surface modification using thiolated ligands allows us to use them for many specific applications. But the effect of possible ligand exchange on 2D-MoS2 has never been explored, which can play an important role in diverse biological applications. In this study, we have observed the ligand-exchange phenomenon on 2D-MoS2 in the presence of different thiolated ligands. The initial study proceeded with boron-dipyrromethene (BODIPY) functionalized MoS2 with different concentrations of glutathione (GSH), which is the most abundant thiol species in the cytoplasm of various cancer cells. It was found that in the presence of GSH the fluorescence of BODIPY can be regenerated, which is time and concentration dependent. We have also examined this phenomenon with different thiol ligands and transition-metal dichalcogenides (TMDs). We observed a variable rate of ligand exchange in different solvents, surface functionality, and receptor environments that helped us to construct sensor arrays. Interestingly, a ligand-exchange process was not observed in the presence of dithiols. Further, this concept was applied to a cancerous cell line for in vitro delivery. We found that BODIPY-functionalized 2D-MoS2 undergoes thiol exchange by intracellular GSH and subsequently enhanced the fluorescence in the cytoplasm of cancer cells. This strategy can be applied to the development of 2D-TMD-based materials for various biological applications related to ligand exchange.

Superoxide dismutase inhibits cytotoxic killing of Fasciola gigantica newly excysted juveniles expressed by sheep invitro

Fasciola gigantica faces a series of threats from various free radicals produced by the host immune system during its invasion through the abdominal cavity and establishment in the bile duct of ruminants, limiting the fluke viability. The role of the superoxide radical produced by Muzaffarnagari sheep immune effector cells against F. gigantica newly excysted juveniles (NEJs) is highlighted in this study, as is the critical role of superoxide dismutase enzyme (SOD) in dismutation of superoxide radicals derived from host immune effector cells in vitro. Three concentrations of the ovine immune effector cells viz. 2.5, 5, and 10 × 10⁶ cells were tested for their ability to induced cytotoxic killing of the parasite. All the three cell concentrations caused significant (p < 0.01) cytotoxic killing of NEJs in comparison to the control groups. Also, reduction of the immune effector cell concentration directly correlates with the NEJs killing. Attachment of immune effector cells to the parasite tegument in the presence of anti-F. gigantica antibodies was found to be critical in inducing NEJs killing via antibody-dependent cell-mediated cytotoxicity (ADCC). However, the addition of SOD greatly inhibits cytotoxic killing of NEJs, demonstrating the importance of SOD enzyme in fluke survival and parasite evasion of the host immunity. Thus, F. gigantica SOD warrants a promising candidate for immunoprophylactic studies in ruminants against the tropical liver fluke.

Dual Role of MoS2 Quantum Dots in a Cross-Dehydrogenative Coupling Reaction

Modern day research focuses on the development of greener and eco-friendlier protocols to fabricate biologically relevant targets with minimal waste generation. C-C bond formation reactions are of prime importance in this regard. In a typical photocatalytic hydrogen evolution reaction, three components are used, viz, catalyst, photosensitizer, and sacrificial amine donor. Among these, the photosensitizer and sacrificial amine donors are wasted at the end of the reaction. Considering these drawbacks, in this work, we have developed a methodology targeted at the utilization of sacrificial amine donors for C-H functionalization with MoS2 quantum dots (QDs) as the catalyst as well as the photosensitizer. QDs indeed emerged to be an active participant in the heterogeneous electron transfer process. This concept opens up new possibilities in the field of nanomaterial-based photomediated organic transformations without the aid of any external photosensitizers via a clean and sustainable protocol with no side product.

Measurement of Two-Particle Correlations of Hadrons in e^{+}e^{-} Collisions at Belle

The measurement of two-particle angular correlation functions in high-multiplicity e^{+}e^{-} collisions at sqrt[s]=10.52  GeV is reported. In this study, the 89.5  fb^{-1} of hadronic e^{+}e^{-} annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.

Search for a Light Higgs Boson in Single-Photon Decays of ϒ(1S) Using ϒ(2S)→π^{+}π^{-}ϒ(1S) Tagging Method

We search for a light Higgs boson (A^{0}) decaying into a τ^{+}τ^{-} or μ^{+}μ^{-} pair in the radiative decays of ϒ(1S). The production of ϒ(1S) mesons is tagged by ϒ(2S)→π^{+}π^{-}ϒ(1S) transitions, using 158×10^{6} ϒ(2S) events accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant A^{0} signals in the mass range from the τ^{+}τ^{-} or μ^{+}μ^{-} threshold to 9.2  GeV/c^{2} are observed. We set the upper limits at 90% credibility level (C.L.) on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→τ^{+}τ^{-} varying from 3.8×10^{-6} to 1.5×10^{-4}. Our results represent an approximately twofold improvement on the current world best upper limits for the ϒ(1S)→γA^{0}(→τ^{+}τ^{-}) production. For A^{0}→μ^{+}μ^{-}, the upper limits on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→μ^{+}μ^{-} are at the same level as the world average limits, and vary from 3.1×10^{-7} to 1.6×10^{-5}. The upper limits at 90% credibility level on the Yukawa coupling f_{ϒ(1S)} and mixing angle sinθ_{A^{0}} are also given.

Measurement of Differential Branching Fractions of Inclusive B→X_{u}ℓ^{+}ν_{ℓ} Decays

The first measurements of differential branching fractions of inclusive semileptonic B→X_{u}ℓ^{+}ν_{ℓ} decays are performed using the full Belle data set of 711  fb^{-1} of integrated luminosity at the ϒ(4S) resonance and for ℓ=e, μ. With the availability of these measurements, new avenues for future shape-function model-independent determinations of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| can be pursued to gain new insights in the existing tension with respect to exclusive determinations. The differential branching fractions are reported as a function of the lepton energy, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic B→X_{c}ℓ^{+}ν_{ℓ} decays and other processes, and corrected for resolution and acceptance effects.

Measurements of the Branching Fractions of the Semileptonic Decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} and the Asymmetry Parameter of Ξ_{c}^{0}→Ξ^{-}π^{+}

Using data samples of 89.5 and 711  fb^{-1} recorded at energies of sqrt[s]=10.52 and 10.58 GeV, respectively, with the Belle detector at the KEKB e^{+}e^{-} collider, we report measurements of branching fractions of semileptonic decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} (ℓ=e or μ) and the CP-asymmetry parameter of Ξ_{c}^{0}→Ξ^{-}π^{+} decay. The branching fractions are measured to be B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})=(1.31±0.04±0.07±0.38)% and B(Ξ_{c}^{0}→Ξ^{-}μ^{+}ν_{μ})=(1.27±0.06±0.10±0.37)%, and the decay parameter α_{Ξπ} is measured to be 0.63±0.03±0.01 with much improved precision compared with the current world average. The corresponding ratio B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})/B(Ξ_{c}^{0}→Ξ^{-}μ^{+}ν_{μ}) is 1.03±0.05±0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter A_{CP}=(α_{Ξ^{-}π^{+}}+α_{Ξ[over ¯]^{+}π^{-}})/(α_{Ξ^{-}π^{+}}-α_{Ξ[over ¯]^{+}π^{-}})=0.024±0.052±0.014 is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the Ξ_{c}^{0}→Ξ^{-}π^{+} branching fraction.

Machine Learning-Assisted Array-Based Detection of Proteins in Serum Using Functionalized MoS2 Nanosheets and Green Fluorescent Protein Conjugates

Abnormal concentrations of a specific protein or the presence of some biomarker proteins may indicate life-threatening diseases. Pattern-based detection of specific analytes using affinity-regulated receptors is one of the potential alternatives to specific antigen-antibody-based detection. In this report, we have schemed a sensor array by using various functionalized two-dimensional (2D)-MoS2 nanosheets and green fluorescent protein (GFP) as the receptor and the signal transducer, respectively. Two-dimensional MoS2 has been used as a promising candidate for recognition of the bioanalytes because of its high surface-to-volume ratio compared to those of other nanomaterials. Easy surface tunability of this material provides additional advantages to analyze the target of interest. The optimized 2D-MoS2-GFP conjugates are able to discriminate 15 different proteins at 50 nM concentration with a detection limit of 1 nM. Moreover, proteins in the binary mixture and in the presence of serum were discriminated successfully. Ten different proteins in serum media at relevant concentrations were classified successfully with 100% jackknifed classification accuracy, which proves the potentiality of the above system. We have also implemented and discussed the implication of using different machine learning models on the pattern recognition problem associated with array-based sensing.

Test of Lepton-Flavor Universality in B→K^{*}ℓ^{+}ℓ^{-} Decays at Belle

We present a measurement of R_{K^{*}}, the branching fraction ratio B(B→K^{*}μ^{+}μ^{-})/B(B→K^{*}e^{+}e^{-}), for both charged and neutral B mesons. The ratio for the charged case R_{K^{*+}} is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass q^{2}. The analysis is based on a data sample of 711  fb^{-1}, containing 772×10^{6}  BB[over ¯] events, recorded at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The obtained results are consistent with standard model expectations.

Evidence for X(3872)→J/ψπ^{+}π^{-} Produced in Single-Tag Two-Photon Interactions

We report the first evidence for X(3872) production in two-photon interactions by tagging either the electron or the positron in the final state, exploring the highly virtual photon region. The search is performed in e^{+}e^{-}→e^{+}e^{-}J/ψπ^{+}π^{-}, using 825  fb^{-1} of data collected by the Belle detector operated at the KEKB e^{+}e^{-} collider. We observe three X(3872) candidates, where the expected background is 0.11±0.10 events, with a significance of 3.2σ. We obtain an estimated value for Γ[over ˜]_{γγ}B(X(3872)→J/ψπ^{+}π^{-}) assuming the Q^{2} dependence predicted by a cc[over ¯] meson model, where -Q^{2} is the invariant mass squared of the virtual photon. No X(3915)→J/ψπ^{+}π^{-} candidates are found.

Measurement of R(D) and R(D^{*}) with a Semileptonic Tagging Method

The experimental results on the ratios of branching fractions R(D)=B(B[over ¯]→Dτ^{-}ν[over ¯]_{τ})/B(B[over ¯]→Dℓ^{-}ν[over ¯]_{ℓ}) and R(D^{*})=B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}), where ℓ denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D^{*}), based on a data sample containing 772×10^{6}  BB[over ¯] events recorded at the ϒ(4S) resonance with the Belle detector at the KEKB e^{+}e^{-} collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side τ is reconstructed in a purely leptonic decay. The measured values are R(D)=0.307±0.037±0.016 and R(D^{*})=0.283±0.018±0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D^{*}), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D^{*}) performed to date as well as the first result for R(D) based on a semileptonic tagging method.

Observation of the Radiative Decays of ϒ(1S) to χ_{c1}

We report the first observation of the radiative decay of the ϒ(1S) into a charmonium state. The significance of the observed signal of ϒ(1S)→γχ_{c1} is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[ϒ(1S)→γχ_{c1}]=[4.7_{-1.8}^{+2.4}(stat)_{-0.5}^{+0.4}(sys)×10^{-5}]. We also searched for ϒ(1S) radiative decays into χ_{c0,2} and η_{c}(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9  fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider at a center-of-mass energy equal to the ϒ(2S) mass using ϒ(1S) tagging by the ϒ(2S)→ϒ(1S)π^{+}π^{-} transitions.

Haemato-biochemical alterations and oxidative stress associated with naturally occurring porcine circovirus2 infection in pigs

Porcine circovirus2 (PCV2) infection in pigs is one of the major causes of economic loss to the farmers in terms of low production, slow growth and increase post-weaning mortality rate. The effect of PCV2 infection on haemogram, serum biochemical profile and oxidant/anti-oxidant status is not well established in pigs. In the present study, haemogram, serum biochemical profile and oxidant/anti-oxidant status were assessed in pigs confirmed positive for PCV2 infections as evidenced by commercially available enzyme-linked immunosorbent assay kit (n = 151) and polymerase chain reaction (PCR) (n = 42) among a total of 306 number of pigs included in the study. Non-infected healthy pigs (n = 6) served as healthy control. The total erythrocyte count (TEC), haemoglobin (Hb), packed cell volume (PCV), total leukocyte count (TLC), differential leukocyte count (DLC) and thrombocyte count were measured. The levels of total protein, albumin, globulin, total bilirubin, direct bilirubin, blood urea nitrogen (BUN), creatinine and glucose and enzymes viz. alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP) were measured. Oxidative stress indicators such as plasma malondialdehyde (MDA) and total anti-oxidant activity (TAOA) were measured using commercially available kits. The mean values of TLC, lymphocytes and thrombocyte count were significantly (P < 0.05) low in PCV2-infected pigs. The levels of globulin, AST, GGT, BUN and creatinine were significantly increased (P < 0.05) whereas levels of albumin and glucose significantly (P < 0.05) decreased in PCV2-infected pigs. The significant increase (P < 0.05) in MDA level and significant decrease (P < 0.05) in TAOA level were noticed in PCV2-infected animals as compared with healthy control. The present study supports immunosuppression, possible multiple organ damage and oxidative stress associated with naturally occurring PCV2 infection in pigs. Timely vaccination and managemental practices can reduce PCV2 infection in farms. In spite of many research studies, there is still paucity of detailed systemic study on haemato-biochemical alteration and oxidative stress associated with PCV2 infection.

Observation of Transverse Λ/Λ[over ¯] Hyperon Polarization in e^{+}e^{-} Annihilation at Belle

We report the first observation of the spontaneous polarization of Λ and Λ[over ¯] hyperons transverse to the production plane in e^{+}e^{-} annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive Λ/Λ[over ¯] production, we also report results with subtracted feed-down contributions from Σ^{0} and charm. This measurement uses a dataset of 800.4  fb^{-1} collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV. We observe a significant polarization that rises with the fractional energy carried by the Λ/Λ[over ¯] hyperon.

Search for a Light CP-odd Higgs Boson and Low-Mass Dark Matter at the Belle Experiment

We report on the first Belle search for a light CP-odd Higgs boson, A^{0}, that decays into low mass dark matter, χ, in final states with a single photon and missing energy. We search for events produced via the dipion transition ϒ(2S)→ϒ(1S)π^{+}π^{-}, followed by the on-shell process ϒ(1S)→γA^{0} with A^{0}→χχ, or by the off-shell process ϒ(1S)→γχχ. Utilizing a data sample of 157.3×10^{6} ϒ(2S) decays, we find no evidence for a signal. We set limits on the branching fractions of such processes in the mass ranges M_{A^{0}}<8.97  GeV/c^{2} and M_{χ}<4.44  GeV/c^{2}. We then use the limits on the off-shell process to set competitive limits on WIMP-nucleon scattering in the WIMP mass range below 5  GeV/c^{2}.

First Evidence for cos2β>0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity

We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^{0}→D^{(*)}h^{0} with D→K_{S}^{0}π^{+}π^{-} decays, where h^{0}∈{π^{0},η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6}BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6}BB[over ¯] pairs recorded by the Belle detector. The results of the measurement are sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β=[22.5±4.4(stat)±1.2(syst)±0.6(model)]°. The measurement assumes no direct CP violation in B^{0}→D^{(*)}h^{0} decays. The quoted model uncertainties are due to the composition of the D^{0}→K_{S}^{0}π^{+}π^{-} decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e^{+}e^{-}→cc[over ¯] data sample. CP violation is observed in B^{0}→D^{(*)}h^{0} decays at the level of 5.1 standard deviations. The significance for cos2β>0 is 3.7 standard deviations. The trigonometric multifold solution π/2-β=(68.1±0.7)° is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.

Observation of ϒ(2S)→γη_{b}(1S) Decay

We report the observation of ϒ(2S)→γη_{b}(1S) decay based on an analysis of the inclusive photon spectrum of 24.7  fb^{-1} of e^{+}e^{-} collisions at the ϒ(2S) center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure a branching fraction of B[ϒ(2S)→γη_{b}(1S)]=(6.1_{-0.7-0.6}^{+0.6+0.9})×10^{-4} and derive an η_{b}(1S) mass of 9394.8_{-3.1-2.7}^{+2.7+4.5}  MeV/c^{2}, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.

Observation of ϒ(4S)→η^{'}ϒ(1S)

We report the first observation of the hadronic transition ϒ(4S)→η^{'}ϒ(1S), using 496  fb^{-1} data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We reconstruct the η^{'} meson through its decays to ρ^{0}γ and to π^{+}π^{-}η, with η→γγ. We measure B(ϒ(4S)→η^{'}ϒ(1S))=[3.43±0.88(stat)±0.21(syst)]×10^{-5}, with a significance of 5.7σ.

Search for B^{-}→μ^{-}ν[over ¯]_{μ} Decays at the Belle Experiment

We report the results of a search for the rare, purely leptonic decay B^{-}→μ^{-}ν[over ¯]_{μ} performed with a 711  fb^{-1} data sample that contains 772×10^{6}  BB[over ¯] pairs, collected near the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B^{-}→μ^{-}ν[over ¯]_{μ})=(6.46±2.22±1.60)×10^{-7} or a frequentist 90% confidence level interval on the B^{-}→μ^{-}ν[over ¯]_{μ} branching fraction of [2.9,10.7]×10^{-7}.

Evidence for Isospin Violation and Measurement of CP Asymmetries in B→K^{*}(892)γ

We report the first evidence for isospin violation in B→K^{*}γ and the first measurement of the difference of CP asymmetries between B^{+}→K^{*+}γ and B^{0}→K^{*0}γ. This analysis is based on the data sample containing 772×10^{6}BB[over ¯] pairs that was collected with the Belle detector at the KEKB energy-asymmetric e^{+}e^{-} collider. We find evidence for the isospin violation with a significance of 3.1σ, Δ_{0+}=[+6.2±1.5(stat)±0.6(syst)±1.2(f_{+-}/f_{00})]%, where the third uncertainty is due to the uncertainty on the fraction of B^{+}B^{-} to B^{0}B[over ¯]^{0} production in ϒ(4S) decays. The measured value is consistent with predictions of the standard model. The result for the difference of CP asymmetries is ΔA_{CP}=[+2.4±2.8(stat)±0.5(syst)]%, consistent with zero. The measured branching fractions and CP asymmetries for charged and neutral B meson decays are the most precise to date. We also calculate the ratio of branching fractions of B^{0}→K^{*0}γ to B_{s}^{0}→ϕγ.

Measurement of the τ Lepton Polarization and R(D^{*}) in the Decay B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ}

We report the first measurement of the τ lepton polarization P_{τ}(D^{*}) in the decay B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ} as well as a new measurement of the ratio of the branching fractions R(D^{*})=B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}), where ℓ^{-} denotes an electron or a muon, and the τ is reconstructed in the modes τ^{-}→π^{-}ν_{τ} and τ^{-}→ρ^{-}ν_{τ}. We use the full data sample of 772×10^{6}  BB[over ¯] pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, P_{τ}(D^{*})=-0.38±0.51(stat)_{-0.16}^{+0.21}(syst) and R(D^{*})=0.270±0.035(stat)_{-0.025}^{+0.028}(syst), are consistent with the theoretical predictions of the standard model.

Lepton-Flavor-Dependent Angular Analysis of B→K^{*}ℓ^{+}ℓ^{-}

We present a measurement of angular observables and a test of lepton flavor universality in the B→K^{*}ℓ^{+}ℓ^{-} decay, where ℓ is either e or μ. The analysis is performed on a data sample corresponding to an integrated luminosity of 711  fb^{-1} containing 772×10^{6} BB[over ¯] pairs, collected at the ϒ(4S) resonance with the Belle detector at the asymmetric-energy e^{+}e^{-} collider KEKB. The result is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of 2.6σ.

Observation of D^{0}→ρ^{0}γ and Search for CP Violation in Radiative Charm Decays

We report the first observation of the radiative charm decay D^{0}→ρ^{0}γ and the first search for CP violation in decays D^{0}→ρ^{0}γ, ϕγ, and K[over ¯]^{*0}(892)γ, using a data sample of 943  fb^{-1} collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The branching fraction is measured to be B(D^{0}→ρ^{0}γ)=(1.77±0.30±0.07)×10^{-5}, where the first uncertainty is statistical and the second is systematic. The obtained CP asymmetries A_{CP}(D^{0}→ρ^{0}γ)=+0.056±0.152±0.006, A_{CP}(D^{0}→ϕγ)=-0.094±0.066±0.001, and A_{CP}(D^{0}→K[over ¯]^{*0}γ)=-0.003±0.020±0.000 are consistent with no CP violation. We also present an improved measurement of the branching fractions B(D^{0}→ϕγ)=(2.76±0.19±0.10)×10^{-5} and B(D^{0}→K[over ¯]^{*0}γ)=(4.66±0.21±0.21)×10^{-4}.

Effects of humidity on the sliding wear properties of Zn–Ni alloy coatings

Formation of nanocrystalline ZnO film on sliding wear tracks at high humidity levels reduces the wear.

Dealing with sub-trochanteric fracture in a child with osteopetrosis : A case report

Osteopetrosis is a rare hereditary condition which may have autosomal recessive or autosomal dominant inheritance. Patients tend to present most commonly with fractures but involvement of cranial nerves and hematopoetic system is not uncommon. Patients with infantile and intermediate type tend to present more often with problems other than orthopaedic problems. While diagnosis can be made on the basis of radiographs, management needs to be customized for every patient. Non operative and operative management both have their advantages and disadvantages. We are here reporting a case of sub-trochanteric fracture in an eight-year-old child which was managed successfully with a dynamic hip screw (DHS). Surgery could be performed successfully by taking precautions during reduction, drilling and screw placement. At the latest follow up, which was after one and half years of surgery, the fracture had united well and the child faced no limitations of activities. Thus, open reduction and fixation with DHS can be considered as an effective management modality for pediatric sub-trochanteric fractures in osteopetrosis.

Energy Scan of the e^{+}e^{-}→h_{b}(nP)π^{+}π^{-} (n=1, 2) Cross Sections and Evidence for ϒ(11020) Decays into Charged Bottomoniumlike States

Using data collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider, we measure the energy dependence of the e^{+}e^{-}→h_{b}(nP)π^{+}π^{-} (n=1, 2) cross sections from thresholds up to 11.02 GeV. We find clear ϒ(10860) and ϒ(11020) peaks with little or no continuum contribution. We study the resonant substructure of the ϒ(11020)→h_{b}(nP)π^{+}π^{-} transitions and find evidence that they proceed entirely via the intermediate isovector states Z_{b}(10610) and Z_{b}(10650). The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Z_{b}(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Z_{b}(10650) is produced is not excluded at a significant level.

Observation of Z_{b}(10610) and Z_{b}(10650) Decaying to B Mesons

We report the analysis of the three-body e^{+}e^{-}→BB[over ¯]π^{±}, BB[over ¯]^{*}π^{±}, and B^{*}B[over ¯]^{*}π^{±} processes, including the first observations of the Z_{b}^{±}(10610)→[BB[over ¯]^{*}+c.c.]^{±} and Z_{b}^{±}(10650)→[B^{*}B[over ¯]^{*}]^{±} transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ(e^{+}e^{-}→[BB[over ¯]^{*}+c.c.]^{±}π^{∓})=[17.4±1.6(stat)±1.9(syst)]  pb and σ(e^{+}e^{-}→[B^{*}B[over ¯]^{*}]^{±}π^{∓})=[8.75±1.15(stat)±1.04(syst)]  pb and set a 90% C.L. upper limit of σ(e^{+}e^{-}→[BB[over ¯]]^{±}π^{∓})<2.9  pb. The results are based on a 121.4  fb^{-1} data sample collected with the Belle detector at a center-of-mass energy near the ϒ(10860) peak.

Observation of the Decay B_{s}^{0}→K^{0}K[over ¯]^{0}

We measure the decay B_{s}^{0}→K^{0}K[over ¯]^{0} using data collected at the ϒ(5S) resonance with the Belle detector at the KEKB e^{+}e^{-} collider. The data sample used corresponds to an integrated luminosity of 121.4  fb^{-1}. We measure a branching fraction B(B_{s}^{0}→K^{0}K[over ¯]^{0})=[19.6_{-5.1}^{+5.8}(stat)±1.0(syst)±2.0(N_{B_{s}^{0}B[over ¯]_{s}^{0}})]×10^{-6} with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.