Search

With the advent of the Internet and other digital technologies, contemporary businesses from all sectors are using social media for communication with consumers to engage them meaningfully with a brand. However, the use of social media for corporate social responsibility (CSR) communication is relatively new to the existing literature. Likewise, the impact of CSR communication through social media (CSR-S) on consumer emotions and behavior is, to date, underexplored. To address this, the present research aims to test the relationship of CSR-S on brand admiration and consumer purchase intention. The study proposes a direct relationship between CSR-S and purchase intention with a mediating effect of brand admiration. The data were collected from the banking consumers of Pakistan through a self-administered questionnaire. The authors distributed 800 questionnaires and received 463 questionnaires useful for data analysis, so the present research study response rate was around 59%. The data were analyzed using the structural equation modeling (SEM) technique in AMOS. The results revealed that CSR-S is positively related to purchase intention (β = 0.233). The results further showed that brand admiration partially mediates this relationship (β = 0.079). The survey respondents confirmed that their bank’s CSR communication helps enhance their purchase likelihood and their feelings of admiration for their bank. These findings will help policymakers at banking institutions better understand the importance of CSR communication on different social media platforms to achieve consumer-related outcomes.

By performing the Density functional theory based first principle calculations, we investigate the effect of z-axial (compressive and tensile) strain on the electronic band structure and transport coefficients of Janus MoSSe monolayer. The unstrained Janus MoSSe monolayer is a direct band gap semiconductor having an energy gap of 1.63 eV. The electronic band structure is very sensitive to the application of z-axial strain. Because of which the electronic transport coefficients get modulated. We found out that z-axial tensile strain enhances the power factor of n-type Janus MoSSe monolayer, however no enhancement is predicted for p-type Janus MoSSe monolayer

International trade plays a vital role in the Indian economy. As the country need to import diverse products so International trade is extremely important to country. India exports vast number of products and also imports an equal amount of other products. Although India has steadily opened up its economy, its tariffs continue to be high when compared with other countries, and its investment norms are still restrictive. This leads some to see India as a ‘rapid globalizer’ while others still see it as a ‘highly protectionist’ economy. Nonetheless, in recent years, the government’s stand on trade and investment policy has displayed a marked shift from protecting ‘producers’ to benefiting ‘consumers’. India is now aggressively pushing for a more liberal global trade regime, especially in services. This paper is an attempt to analyse the major changes in volume, composition and direction of International Trade of India.

Modeling of a graphene nanoribbon field effect transistor (GNRFET) as a frequency doubler has been extensively explored for developing future communication applications. For its analysis, different types of modifications are applied to the GNRFET model simulated in a Hewlett simulation program with an integrated circuit. The model is demonstrated for its frequency response and conversion gain. It uses an intrinsic GNRFET for frequency doubling which clearly shows a distortionless sinusoidal output at a peak frequency of 20.6 MHz for an applied input of 10.3 MHz. However, after applying doping at different fractions of 0.3%, 3% and 30% in the transistor model, signal decay appears at 30% doping fractions. Results are also shown for increasing the number of dimers (N), increasing the number of channels for conduction and the impact of changing the dielectric constant on the doubler model performance. It is found that as the channel width increases, an increase in the conversion gain from − 26.05 dB to − 20 dB results from an increase in N from 8 to 20 dimer lines. Further, if four graphene nanoribbon (GNR) channels are used in the doubler operation instead of one GNR channel, then a high conversion gain of − 16.47 dB as compared to − 26.05 dB for an individual GNR channel is also calculated. Regarding the impact of different dielectrics, it is revealed that, similar to a conventional transistor, a graphene transistor with a high-K-value dielectric presents the highest gain, but with a high distortion in the output signal. However, using a conventional silicon dioxide (SiO2) dielectric having a low K value gives lower conversion gain, but ideal frequency doubling in the output is attained.

Social media has emerged as a flexible and interactive communication medium in the present digital era. Contemporary businesses use social media to achieve different communication objectives. However, using social media as a communication medium for corporate social responsibility (CSR) communication with stakeholders like, consumers is not well-explored in the existing literature. Furthermore, prior studies have also failed to consider the blend of CSR communication and social media to achieve consumer-related outcomes, for example, their loyalty and purchase likelihood. To this end, the objective of this study is to examine the relationship of the CSR communication of a bank through social media with consumer loyalty and purchase intention. The current study also proposes brand admiration as a potential mediator between this relationship. The data were collected from the banking consumers through a self-administered questionnaire in a developing economy. The data were analyzed through the structural equation modeling (SEM) technique using AMOS software. The results of the current survey confirmed that CSR communication of a bank on social media has direct and indirect, via brand admiration, relations with consumer loyalty, and purchase intentions. The outcomes of this survey will be helpful for the policymakers to understand the importance of CSR communication on social media to enhance the loyalty, and purchase intention of banking consumers.

The agency problem strikes as an ethical, practical, and economic issue in equal measures. The principal objective of the current research is to trace the nature of the agency conflicts in the family-owned pyramidal business groups of corporate Malaysia and how they affect the firm value. It is argued that the principa͐l-principal (PP) conflict is more severe in family-owned business firms. To achieve the objectives of the current study, the GMM and the fixed effect estimates are used. In addition, to find the difference between family-owned firms and family-owned firms in the pyramidal business, we have employed the Mann-Whitney test. The null hypothesis is accepted which indicates that the impact of the PP conflict among family firms is different from those in pyramidal business groups. The final sample of 420 firms listed on the Bursa Malaysia is chosen for the analysis. The results of the current study provide support to the hypothesized results that the PP conflict is severe in family-owned groups and has a significant effect on firm value. The findings of the current study also provide support that the PP conflict is prevalent in Malaysia, supporting the earlier evidence regarding the expropriation of minority shareholders rights reported in the studies carried out on samples of Malaysian non-financial firms. This is also in line with our measure of PP conflict severity, which is high in pyramidal family firms. Overall, the results provided support to the expropriation hypothesis. Thus, the findings of this study also confirm the view that in family-owned Malaysian firms, the ethical dilemmas of wealth expropriations do exist and are more intense in the pyramidal family-owned business structures. Instead of relying on traditional methods, the current study employed a synthetic measure to gauge the PP conflict. The study which is among the pioneer on the expropriation of minority shareholders will be helpful for policymakers, researchers and finance professionals in understanding the issues related to principal-principal conflict, and firm value in family-owned pyramidal business groups of Malaysia.

Graphene-based photodetectors have shown responsivities up to 10$^8$A/W and photoconductive gains up to 10$^{8}$ electrons per photon. These photodetectors rely on a highly absorbing layer in close proximity of graphene, which induces a shift of the graphene chemical potential upon absorption, hence modifying its channel resistance. However, due to the semi-metallic nature of graphene, the readout requires dark currents of hundreds of $\mu$A up to mA, leading to high power consumption needed for the device operation. Here we propose a novel approach for highly responsive graphene-based photodetectors with orders of magnitude lower dark current levels. A shift of the graphene chemical potential caused by light absorption in a layer of colloidal quantum dots, induces a variation of the current flowing across a metal-insulator-graphene diode structure. Owing to the low density of states of graphene near the neutrality point, the light-induced shift in chemical potential can be relatively large, dramatically changing the amount of current flowing across the insulating barrier, and giving rise to a novel type of gain mechanism. This readout requires dark currents of hundreds of nA up to few $\mu$A, orders of magnitude lower than other graphene-based photodetectors, while keeping responsivities of $\sim$70A/W in the infrared, almost two orders of magnitude higher compared to established germanium on silicon and indium gallium arsenide infrared photodetectors. This makes the device appealing for applications where high responsivity and low power consumption are required., Comment: 14 pages, 7 figures

Recent approaches to develop infrared photodetectors characterized by high sensitivities, broadband spectral coverage, easy integration with silicon electronics and low cost have been based on hybrid structures of transition metal dichalcogenides (TMDCs) and PbS colloidal quantum dots (CQDs). However, to date, such photodetectors have been reported with high sensitivity up to 1.5 $\mu$m. Here we extend the spectral coverage of this technology towards 2 $\mu$m demonstrating for the first time compelling performance with responsivities 1400 A/W at 1.8 $\mu$m with 1V bias and detectivities as high as $10^{12}$ Jones at room temperature. To do this we studied two TMDC materials as a carrier transport layer, tungsten disulfide (WS$_2$) and molybdenum disulfide (MoS$_2$) and demonstrate that WS$_2$ based hybrid photodetectors outperform those of MoS$_2$ due to a more adequate band alignment that favors carrier transfer from the CQDs., Comment: 24 pages including Supporting Information

Optical sensing in the mid- and long-wave infrared (MWIR, LWIR) is of paramount importance for a large spectrum of applications including environmental monitoring, gas sensing, hazard detection, food and product manufacturing inspection, and so forth. Yet, such applications to date are served by costly and complex epitaxially grown HgCdTe quantum-well and quantum-dot infrared photodetectors. The possibility of exploiting low-energy intraband transitions make colloidal quantum dots (CQD) an attractive low-cost alternative to expensive low bandgap materials for infrared applications. Unfortunately, fabrication of quantum dots exhibiting intraband absorption is technologically constrained by the requirement of controlled heavy doping, which has limited, so far, MWIR and LWIR CQD detectors to mercury-based materials. Here, we demonstrate intraband absorption and photodetection in heavily doped PbS colloidal quantum dots in the 5-9 µm range, beyond the PbS bulk band gap, with responsivities on the order of 10-4 A/W at 80 K. We have further developed a model based on quantum transport equations to understand the impact of electron population of the conduction band in the performance of intraband photodetectors and offer guidelines toward further performance improvement. I.R. acknowledges support from the Ministerio de Economiá , Industria y Competitividad of Spain via a Juan de la Cierva fellowship. The authors acknowledge financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement 725165), the Spanish Ministry of Economy and Competitiveness (MINECO), and the “Fondo Europeo de Desarrollo Regional” (FEDER) through Grant TEC2017- 88655-R. The authors also acknowledge financial support from Fundacio Privada Cellex, the program CERCA and from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0522). S.C. acknowledge support from a Marie Curie Standard European Fellowship (“NAROBAND”, H2020-MSCA-IF-2016-750600).

Integrated circuits based on complementary metal-oxide–semiconductors (CMOS) are at the heart of the technological revolution of the past 40 years, enabling compact and low-cost microelectronic circuits and imaging systems. However, the diversification of this platform into applications other than microcircuits and visible-light cameras has been impeded by the difficulty to combine semiconductors other than silicon with CMOS. Here, we report the monolithic integration of a CMOS integrated circuit with graphene, operating as a high-mobility phototransistor. We demonstrate a high-resolution, broadband image sensor and operate it as a digital camera that is sensitive to ultraviolet, visible and infrared light (300–2,000 nm). The demonstrated graphene–CMOS integration is pivotal for incorporating 2D materials into the next-generation microelectronics, sensor arrays, low-power integrated photonics and CMOS imaging systems covering visible, infrared and terahertz frequencies. Graphene–quantum dots on CMOS sensor offers broadband imaging.

To explore communication applications, a study towards achieving linearity in the I–V characteristics through increasing concentrations of Boron (B) / Nitrogen (N) doping on pristine graphene sheet is investigated. Individual B/N doping of 6.25, 12.50, 18.75 and 25% has been done in the same sub lattice using Density Functional Theory (DFT) along with Non Equilibrium Greens Function (NEGF) calculations. The modification in the electronic and transport properties of graphene sheet are also investigated. In comparison to the variation of band gap from 0.35 to 1.183 eV and 0.36 to 1.149 eV for B and N respectively, an insignificant variation in effective mass is reported. Apart from linearity, variation in conductance in doped structures is seen. B doping increases conductivity and yields ON current of 610 µA while N doping gives ON current of 310 µA for maximum doping concentrations. In this work, the sustained carrier mobility and high gain linear characteristics of doped graphene obtained will help to utilise a graphene channel for different communication device applications.

Flexible and transparent graphene photodetector technology allows non-invasive monitoring of vital signs., Wearable health and wellness trackers based on optical detection are promising candidates for public health uses due to their noninvasive tracking of vital health signs. However, so far, the use of rigid technologies hindered the ultimate performance and form factor of the wearable. Here, we demonstrate a new class of flexible and transparent wearables based on graphene sensitized with semiconducting quantum dots (GQD). We show several prototype wearable devices that are able to monitor vital health signs noninvasively, including heart rate, arterial oxygen saturation (SpO2), and respiratory rate. Operation with ambient light is demonstrated, offering low-power consumption. Moreover, using heterogeneous integration of a flexible ultraviolet (UV)–sensitive photodetector with a near-field communication circuit board allows wireless communication and power transfer between the photodetectors and a smartphone, offering battery-free operation. This technology paves the way toward seamlessly integrated wearables, and empowers the user through wireless probing of the UV index.

Colloidal quantum dot (CQD) light-emitting diodes (LEDs) deliver a compelling performance in the visible, yet infrared CQD LEDs underperform their visible-emitting counterparts, largely due to their low photoluminescence quantum efficiency. Here we employ a ternary blend of CQD thin film that comprises a binary host matrix that serves to electronically passivate as well as to cater for an efficient and balanced carrier supply to the emitting quantum dot species. In doing so, we report infrared PbS CQD LEDs with an external quantum efficiency of ~7.9% and a power conversion efficiency of ~9.3%, thanks to their very low density of trap states, on the order of 1014 cm−3, and very high photoluminescence quantum efficiency in electrically conductive quantum dot solids of more than 60%. When these blend devices operate as solar cells they deliver an open circuit voltage that approaches their radiative limit thanks to the synergistic effect of the reduced trap-state density and the density of state modification in the nanocomposite. PbS quantum dot ternary blends enable the realization of high-efficiency colloidal quantum dot infrared light-emitting diodes

Background: Genioplasty has nowadays become a routine procedure in the correction of dentofacial deformities. The present study aimed to evaluate and compare the osseous and soft-tissue stability after advancement genioplasties, stabilized using wire and plate osteosynthesis. Methodology: The study was conducted on ten patients who underwent advanced genioplasty. The patients were divided equally into two groups. In the Group I patients, plates and in Group II, wires were used for stabilization. Lateral cephalograms preoperative and 6 months postoperative were analyzed using Park et al. method of cephalometric analysis. Results: All the ten patients experienced a reliable improvement in esthetics. Although statistically not significant, Group II wire patients have slightly more relapse in the horizontal direction than Group I. The mean ratio of sagittal changes of osseous soft tissue for Group I was 1:0.88 and for Group II wires was 1:0.80. Conclusion: The choice of method of fixation following genioplasty would entirely be based on the merits of the individual cases. The marginal edge of advantage seen in miniplate osteosynthesis when compared to wire osteosynthesis is seen in cases that require larger chin advancements.

Micro and small scale enterprises are the backbone of any developing economy, with their effective innovative, professional skills. MSEs develop the economy, by generating employment opportunities, reducing regional imbalances, fostering equitable economic growth and alleviating poverty. Ethiopian Government has also recognized the role of Micro and Small Scale Industries in the economic development. Deliberate efforts to promote these industries are already in place in Ethiopia. But there are so many factors, which should be analyzed, for the better performance of these industries, which could help the economy to generate sufficient revenues. Hence this study is an attempt to analyze factors such as entrepreneurs’ skill, access to finance, market, training, legal and regulatory framework and infrastructure, which affect the performance of micro and small enterprises in Ethiopia. Primary data and secondary data were used. Primary data were collected from 198 respondents, by using well organized self-administered questionnaire. For analyzing the data, statistical tools like Pearson's Correlation Coefficient and Regression analyses were used.

Harnessing low energy photons is of paramount importance for multi-junction high efficiency solar cells as well as for thermo-photovoltaic applications. However, semiconductor absorbers with the bandgap lower than 0.8 eV have been limited to III-V (InGaAs) or IV (Ge) semiconductors that are characterized by high manufacturing costs and complicated lattice matching requirements in their growth and integration with higher bandgap cells. Here, we have developed solution processed low bandgap photovoltaic devices based on PbS colloidal quantum dots (CQDs) with a bandgap of 0.7 eV suited for both thermo-photovoltaics and low energy solar photon harvesting. By matching the spectral response of those cells to that of the infrared solar spectrum, we report a record high short circuit current (JSC) of 37 mA cm-2 under the full solar spectrum and 5.5 mA cm-2 when placed at the back of a silicon wafer resulting in power conversion efficiencies (PCEs) of 6.4% and 0.7%, respectively. Moreover, the device reached an above bandgap PCE of ∼6% as a thermo-photovoltaic cell recorded under a 1000 °C blackbody radiator.

Developing low-cost photovoltaic absorbers that can harvest the short-wave infrared (SWIR) part of the solar spectrum, which remains unharnessed by current Si-based and perovskite photovoltaic technologies, is a prerequisite for making high-efficiency, low-cost tandem solar cells. Here, infrared PbS colloidal quantum dot (CQD) solar cells employing a hybrid inorganic-organic ligand exchange process that results in an external quantum efficiency of 80% at 1.35 µm are reported, leading to a short-circuit current density of 34 mA cm-2 and a power conversion efficiency (PCE) up to 7.9%, which is a current record for SWIR CQD solar cells. When this cell is placed at the back of an MAPbI3 perovskite film, it delivers an extra 3.3% PCE by harnessing light beyond 750 nm.

Two-terminal tandem cell architectures are believed to be an effective way to further improve the power conversion efficiency in solution processed photovoltaics. To design an efficient tandem solar cell, two key issues need to be considered. First, subcells with well-matched currents and complementary absorption characteristics are a prerequisite for high efficiency. Second, identifying the appropriate intermediate layer (IML) to connect the subcells is necessary to minimize the optical and electronic losses. PbS colloidal quantum dots (CQDs) are a notable choice for the subcells due to their low cost, solution processability, and remarkable wide range band gap tunability. Single-layer graphene (Gr) has been proposed to be a promising IML due to its high transparency and conductivity. Here, as a proof of concept, we demonstrate a solution-processed, two-terminal PbS CQDs tandem solar cell employing chemical vapor deposited Gr as the IML. In doing so, we report a PbS CQD cell comprising subcells with band...

Background: RTI including Sexually Transmitted Diseases (STD) are increasingly recognized as a major cause of morbidity in India. RTI have become widespread today because of the changing social fabric and unconventional sexual behaviors. The present study was done to assess the prevalence of RTI and STD in women aged 20-45 years and to correlate the socio-demographic factors with RTI & STD. Methods: Two hundred & fifty women in the age group of 20-45 years attending the outpatient department of Obstetrics and Gynecology of VPC & IMS, Lucknow were included in the study. Out of them 215 were symptomatic and 35 were asymptomatic. All of them were offered clinical and microbiological examinations. A pretested, semistructured interview schedule was used. Results: In this study the prevalence of RTI/STD was higher among women aged 31-35years, rural population, illiterate & less educated (90.4-97%) females, in farm workers & in students. The females having toilet access in field & outside toilet and with poor personal and menstrual hygiene, had more prevalence of RTI/STD. Conclusions: Hence we as obstetricians should try to make public aware about the importance of RTI/STD prevention, early diagnosis and prompt and complete treatment to avoid long term squealae.

The power conversion efficiency of colloidal PbS-quantum-dot (QD)-based solar cells is significantly hampered by lower-than-expected open circuit voltage (VOC). The VOC deficit is considerably higher in QD-based solar cells compared to other types of existing solar cells due to in-gap trap-induced bulk recombination of photogenerated carriers. Here, this study reports a ligand exchange procedure based on a mixture of zinc iodide and 3-mercaptopropyonic acid to reduce the VOC deficit without compromising the high current density. This layer-by-layer solid state ligand exchange treatment enhances the photovoltaic performance from 6.62 to 9.92% with a significant improvement in VOC from 0.58 to 0.66 V. This study further employs optoelectronic characterization, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy to understand the origin of VOC improvement. The mixed-ligand treatment reduces the sub-bandgap traps and significantly reduces bulk recombination in the devices.

A simple optical model is presented to describe the influence of a planar luminescent down-shifting layer (LDSL) on the external quantum efficiencies of photovoltaic solar cells. By employing various visible light-emitting LDSLs based on CdTe quantum dots or CdSe/CdS core–shell quantum dots and tetrapods, we show enhancement in the quantum efficiencies of thin-film CdTe/CdS solar cells predominantly in the ultraviolet regime, the extent of which depends on the photoluminescence quantum yield (PLQY) of the quantum dots. Similarly, a broad enhancement in the quantum efficiencies of crystalline Si solar cells, from ultraviolet to visible regime, can be expected for an infrared emitting LDSL based on PbS quantum dots. A PLQY of 80% or higher is generally required to achieve a maximum possible short-circuit current increase of 16 and 50% for the CdTe/CdS and crystalline Si solar cells, respectively. As also demonstrated in this work, the model can be conveniently extended to incorporate LDSLs based on organic ...

The energy gap between valence and conduction levels in colloidal semiconductor quantum dots can be tuned via the nanoparticle diameter when this is comparable to or less than the Bohr radius. In materials such as cadmium mercury telluride, which readily forms a single phase ternary alloy, this quantum confi nement tuning can also be augmented by compositional tuning, which brings a further degree of freedom in the bandgap engineering. Here it is shown that compositional control of 2.3 nm diameter Cd x Hg (1− x ) Te nano crystals by exchange of Hg 2+ in place of Cd 2+ ions can be used to tune their optical properties across a technologically useful range, from 500 nm to almost 1200 nm. Data on composition-dependent changes in the optical properties are provided, including bandgap, extinction coeffi cient, emission energy and spectral shape, Stokes shift, quantum effi ciency, and radiative lifetimes as the exchange process occurs, which are highly relevant for those seeking to use these technologically important QD materials.

The internet has been connecting people and making life simpler by providing all kinds of information with the click of a button. The next big wave in this domain is the internet of things which will enable physical objects used in day to day life to connect to the internet and exchange data. In this paper a home automation system based on internet of things is developed. This allows the user to automate all the devices and appliances of home and integrate them to provide seamless control over every aspect of their home. The designed system not only monitors the sensor data, but also actuates a process according to the requirement, for example switching on the light when it gets dark and it allows the user to control the household devices from anywhere.

Graphene nano ribbons are the strips of graphene sheet which opens band gap in graphene. This opening of band gap increases the on off ratio of these GNR devices and allows its use in logic circuit applications. GNR in transistors give vital applications in these areas. A GNRFET shows large conductance with respect to gate voltages. The effect of temperature on this conductance is seen in this paper by simulating a GNRFET model in VNL. A GNRFET with zigzag electrodes and armchair channel is studied. The conductance with respect to temperature is seen. A temperature range of 0 to 2000 K is selected for the study.

Mercury telluride (HgTe) colloidal quantum dots (CQDs) have been developed as promising materials for the short and mid-wave infrared photodetection applications because of their low cost, solution processing, and size tunable absorption in the short wave and mid-infrared spectrum. However, the low mobility and poor photogain have limited the responsivity of HgTe CQD-based photodetectors to only tens of mA W-1 . Here, HgTe CQDs are integrated on a TiO2 encapsulated MoS2 transistor channel to form hybrid phototransistors with high responsivity of ≈106 A W-1 , the highest reported to date for HgTe QDs. By operating the phototransistor in the depletion regime enabled by the gate modulated current of MoS2 , the noise current is significantly suppressed, leading to an experimentally measured specific detectivity D* of ≈1012 Jones at a wavelength of 2 µm. This work demonstrates for the first time the potential of the hybrid 2D/QD detector technology in reaching out to wavelengths beyond 2 µm with compelling sensitivity.

In India, the collection, transportation and disposal of MSW are unscientific and chaotic. Uncontrolled dumping of wastes on outskirts of towns and cities has created overflowing landfills, which are not only impossible to reclaim because of the haphazard manner of dumping, but also have serious environmental implications in terms of ground water pollution and contribution to global warming. Burning of waste leads to air pollution in terms of increased TSP and PM10 emissions, which is equivalent to vehicular emissions at times. In the absence of waste segregation practices, recycling has remained to be an informal sector working on outdated technology, but nevertheless thriving owing to waste material availability and market demand of cheaper recycled products. Paper and plastic recycling have been especially growing due to continuously increasing consumption levels of both the commodities. Composting-aerobic and anaerobic, both the options are available to the country for scientific disposal of waste in future. However, country also needs something in terms of policy and guidelines to enable the municipal corporations to run the waste services efficiently.

The investigation of sub-nanosecond exciton dynamics in HgTe colloidal quantum dots using ultrafast transient absorption spectroscopy is reported. The transmittance change spectrum acquired immediately after pumping is dominated by a bleach blue-shifted by ∼200–300 nm from the photoluminescent emission band. Comparison with a tight-binding model of the electronic structure allows this feature to be attributed to the filling of band edge states. The form of the pump-induced transmittance transients is dependent on the excitation rate and the rate of sample stirring. For moderate pumping of stirred samples, the transmittance transients are well-described by a mono-exponential decay associated with biexciton recombination, with a lifetime of 49 ± 2 ps. For samples that are strongly-pumped or unstirred, the decay becomes bi-exponential in form, indicating that trap-related recombination has become significant. We also present a new analysis that enables fractional transmittance changes to be related to band edge occupation for samples with arbitrary optical density at the pump wavelength. This allows us to identify the occurrence of multiple exciton generation, which results in a quantum yield of 1.36 ± 0.04 for a photon energy equivalent to 3.1 times the band gap, in good agreement with the results of the model.

The ability to detect near-infrared and mid-infrared radiation has spawned great interest in colloidal HgTe quantum dots (QDs). In contrast to the studies focused on extending the spectral range of HgTe QD devices, the temporal response, another fi gure of merit for photodetectors, is rarely investigated. In this work, a single layer, aqueous HgTe QD based photoconductor structure with very fast temporal response (up to 1 MHz 3 dB bandwidth) is demonstrated. The device is fabricated using a simple spray-coating process and shows excellent stability in ambient conditions. The origin of the remarkably fast time response is investigated by combining light intensity-dependent transient photocurrent, temperature-dependent photocurrent, and fi eld-effect transistor (FET) measurements. The charge carrier mobility, as well as the energy levels and carrier lifetimes associated with the trap states in the QDs, are identifi ed. The results suggest that the temporal response is dominated by a fast bimolecular recombination process under high light intensity and by a trap-mediated recombination process at low light intensity. Interestingly, it was found that the gain and time response of aqueous HgTe QD-based photoconductors can be tuned by controlling the QD size and surface chemistry, which provides a versatile approach to optimize the photodetectors with selectable sensitivity and operation bandwidth.

Context: Survey. Aims: The objective of the study was to evaluate the periodontal health status among cigarette smokers and non cigarette smokers, and oral hygiene measures. Settings and Design: Cross sectional study. Materials and Methods: The study included 400 male (200 cigarette smokers and 200 non smokers) aged 18-65 years. The subjects were randomly selected from the patients attending dental out-patient department of civil hospital and Himachal Dental College, Sundernagar. Community Periodontal Index (CPI) score was recorded for each patient and a questionnaire was completed by each patient. Statistical Analysis Used: Chi square and t-test. Results: Periodontal condition as assessed by CPI score showed that there was statistically significant difference in the findings between cigarette smokers and non-smokers. Conclusions: Within the limits of this study, positive association was observed between periodontal disease and cigarette smoking. It was found that cigarette smoking was associated with lesser gingival bleeding and deeper pockets as compared to non-smokers.

Very little information is available about the incidence of coronary heart disease in India, or of factors considered responsible for it. In a previous paper, the incidence of atherosclerosis as judged by electrocardiogram, the fat intake, and serum cholesterol levels in 2 low-income groups (industrial and rural) in Delhi were investigated. These data in high-income groups in Delhi have now been studied and the results compared. There were considerable differences in the findings in the 2 groups.

The performance of ZnO/PbS colloidal quantum dot (CQD)-based heterojunction solar cells is hindered by charge carrier recombination at the heterojunction interface. Reducing interfacial recombination can improve charge collection and the photocurrent of the device. Here we report the use of a mixed nanocrystal (MNC) buffer layer comprising zinc oxide nanocrystals and lead sulfide quantum dots at the respective heterojunction interface. Remote trap passivation of the PbS CQDs taking place within this MNC layer reduces interfacial recombination and electron back transfer which in turn improves charge collection efficiency. Upon the addition of the MNC layer, the overall power conversion efficiency increases from 9.11 to 10.16% and Short-circuit current density (JSC) increases from 23.54 to 25.23 mA/cm2. Optoelectronic characterization of the solar cells confirms that the effects underlying device improvement are reduced trap density and improved charge collection efficiency due to the presence of the MNC buffer layer.