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Nonmetallic and metallic heteroatom doped carbonaceous materials have garnered tremendous research attention due to a potential replacement to the precious Pt-group and (Ru, Ir)-oxide based catalysts and are essential part of the next-generation electrode catalysts for fuel cells, electrolyzers, and metal-air batteries. In this regard, we focus on three important categories of carbonaceous material, namely, metal-free heteroatom doped, transition metal heteroatom codoped, and carbon nitride (C 3 N 4 ) based hybrid materials. Implications of various strategies, using one-step pyrolysis technique have been discussed for the effective design of heteroatom modified carbonaceous electrocatalysts. In this minireview, we outline the richness of one-step strategy for designing electrochemically active heteroatom doped carbon, transition metal-heteroatom codoped carbon, and C 3 N 4 derived hybrid materials in the perspective of electrochemical energy conversion and storage devices. We also outline the future research direction in the development of highly efficient and sustainable electrocatalysts for oxygen electrochemistry. Finally, we wind up the article with the challenges and outlook on heteroatoms and transition metal-heteroatom codoped carbon material as an efficient and low-cost electrocatalysts, thereby promoting the development of this important area., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Humidity monitoring has become extremely vital in various technological fields such as environment control, biomedical engineering, and so on. Therefore, a substantial interest lies in the development of fast and highly sensitive devices with high figures of merit. Self-powered and ultrasensitive humidity sensors based on SnS 2 nanofilms of different film thicknesses have been demonstrated in this work. The sensing behavior has been investigated in the relative humidity (RH) range of 2-99%. The observed results reveal a remarkable response and ultrafast detection even with zero applied bias (self-powered mode), with response and recovery times of ~ 10 and ~ 0.7 s, respectively. The self-powered behavior has been attributed to the inhomogeneities and the asymmetry in the contact electrodes. The highest sensitivity of ~ 5.64 × 10 6 % can be achieved at an applied bias of 5 V. This approach of fabricating such highly responsive, self-powered and ultrafast sensors with simple device architectures will be useful for designing futuristic sensing devices.

While band gap and absorption coefficients are intrinsic properties of a material and determine its spectral range, response time is mainly controlled by the architecture of the device and electron/hole mobility. Further, 2D-layered materials such as transition metal dichalogenides (TMDCs) possess inherent and intriguing properties such as a layer-dependent band gap and are envisaged as alternative materials to replace conventional silicon (Si) and indium gallium arsenide (InGaAs) infrared photodetectors. The most researched 2D material is graphene with a response time between 50 and 100 ps and a responsivity of <10 mA/W across all wavelengths. Conventional Si photodiodes have a response time of about 50 ps with maximum responsivity of about 500 mA/W at 880 nm. Although the responsivity of TMDCs can reach beyond 10 4 A/W, response times fall short by 3-6 orders of magnitude compared to graphene, commercial Si, and InGaAs photodiodes. Slow response times limit their application in devices requiring high frequency. Here, we highlight some of the recent developments made with visible and near-infrared photodetectors based on two dimensional SnSe 2 and MoS 2 materials and their performance with the main emphasis on the role played by the mobility of the constituency semiconductors to response/recovery times associated with the hetero-structures.

We, for the first time, provide the experimental demonstration on the band gap engineering of layered hexagonal SnSe 2 nanostructured thin films by varying the thickness. For 50 nm thick film, the band gap is ~2.04 eV similar to that of monolayer, whereas the band gap is approximately ~1.2 eV similar to that of bulk for the 1200 nm thick film. The variation of the band gap is consistent with the the theoretically predicted layer-dependent band gap of SnSe 2 . Interestingly, the 400-1200 nm thick films were sensitiveto 1064 nm laser iradiation and the sensitivity increases almost exponentiallly with thickness, while films with 50-140 nm thick are insensitive which is due to the fact that the band gap of thinner films is greater than the energy corresponding to 1064 nm. Over all, our results establish the possibility of engineering the band gap of SnSe 2 layered structures by simply controlling the thickness of the film to absorb a wide range of electromagnetic radiation from infra-red to visible range.

Positively charged functionalized carbon nanodots (CNDs) with a variety of different effective surface areas (ESAs) are synthesized via a cheap and time effective microwave method and applied for the generation of hydrogen via hydrolysis of sodium borohydride. To the best of our knowledge, this is the first report of metal-free controlled hydrogen generation. Our observation is that a positively charged functional group is essential for the hydrolysis for hydrogen production, but the overall activity is found to be enhanced with the ESA. A maximum value of 1066 ml g -1 min -1 as the turnover frequency is obtained which is moderate in comparison to other catalysts. However, the optimum activation energy is found to be 22.01 kJ mol -1 which is comparable to well-known high cost materials like Pt and Ru. All of the samples showed good reusability and 100% conversion even after the 10th cycle. The effect of H + and OH - is also studied to control the on-board and on-demand hydrogen production ("on-off switching"). It is observed that H 2 production decreases inversely with NaOH concentration and ceases completely when 10 -1 M NaOH is added. With the addition of HCl, H 2 production can be initiated again, which confirms the on/off control over production.

Background and Aims: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is closely related to metabolic syndrome and its risk factors. Worldwide, epidemiological studies have reported NAFLD prevalence rates of 5% to 30% depending on geographical variations. While epidemiological data suggest a progressively increasing prevalence of metabolic risk factors in Singapore, there are limited data about NAFLD per se in the community. We aim to explore the prevalence and perceptions of NAFLD in Singapore., Methods: Attendees at a gastroenterology public forum were enrolled in a cross-sectional observational study evaluating demographic, anthropometric and clinical information. The diagnosis of NAFLD was based on sonographic criteria. Metabolic syndrome was defined according to International Diabetes Federation guidelines. Perceptions of NAFLD were explored using a self-administered survey questionnaire., Results: A total of 227 subjects were recruited, with NAFLD being diagnosed in 40% of the cohort. Relative to those without NAFLD, subjects with NAFLD had higher male preponderance, older age, higher body mass index, waist circumference and more metabolic syndrome (all P < 0.05). Although 71.2% subjects had heard about NAFLD before, only 25.4% of them felt that they were at risk of NAFLD. Comparable responses were observed in subjects with no metabolic risk factors relative to subjects with one or more metabolic risk factors (P > 0.05). Of note, 75.6% of subjects with one or more metabolic risk factors did not think that they were at risk of NAFLD., Conclusion: Our study suggests a significant local prevalence of NAFLD in the community including non-obese individuals. Considering the tendency to underestimate risk of NAFLD, enhanced public education about NAFLD is warranted to improve understanding., (© The Author(s) 2015. Published by Oxford University Press and the Digestive Science Publishing Co. Limited.)

Room temperature operation, low detection limit and fast response time are highly desirable for a wide range of gas sensing applications. However, the available gas sensors suffer mainly from high temperature operation or external stimulation for response/recovery. Here, we report an ultrasensitive-flexible-silver-nanoparticle based nanocomposite resistive sensor for ammonia detection and established the sensing mechanism. We show that the nanocomposite can detect ammonia as low as 500 parts-per-trillion at room temperature in a minute time. Furthermore, the evolution of ammonia from different chemical reactions has been demonstrated using the nanocomposite sensor as an example. Our results demonstrate the proof-of-concept for the new detector to be used in several applications including homeland security, environmental pollution and leak detection in research laboratories and many others.

Generally, the length of the oxide nanowires grown by vapor phase transport is limited by the degradation of the source materials. Furthermore, the source material is used once for the nanowires growth. By exploiting the Si-Zn phase diagram, we have developed a simple methodology for the non-catalytic growth of ultralong ZnO nanowires in large area with controllable aspect ratio and branched structures. The insolubility of Zn in Si and the use of a Si cap on the Zn source to prevent local source oxidation of Zn (i. e. prevents the degradation of the source) are the keys to grow longer nanowires without limitations. It has been shown that the aspect ratio can be controlled by thermodynamically (temperature) and more importantly by kinetically (vapor flux). One of the interesting findings is that the same source material can be used for several depositions of oxide nanostructured materials.

Reduced dopamine neurotransmission in the prefrontal cortex has been implicated as causal for the negative symptoms and cognitive deficit associated with schizophrenia; thus, a compound which selectively enhances dopamine neurotransmission in the prefrontal cortex may have therapeutic potential. Inhibition of catechol-O-methyltransferase (COMT, EC 2.1.1.6) offers a unique advantage, since this enzyme is the primary mechanism for the elimination of dopamine in cortical areas. Since membrane bound COMT (MB-COMT) is the predominant isoform in human brain, a high throughput screen (HTS) to identify novel MB-COMT specific inhibitors was completed. Subsequent optimization led to the identification of novel, non-nitrocatechol COMT inhibitors, some of which interact specifically with MB-COMT. Compounds were characterized for in vitro efficacy versus human and rat MB and soluble (S)-COMT. Select compounds were administered to male Wistar rats, and ex vivo COMT activity, compound levels in plasma and cerebrospinal fluid (CSF), and CSF dopamine metabolite levels were determined as measures of preclinical efficacy. Finally, novel non-nitrocatechol COMT inhibitors displayed less potent uncoupling of the mitochondrial membrane potential (MMP) compared to tolcapone as well as nonhepatotoxic entacapone, thus mitigating the risk of hepatotoxicity.

We report the synthesis of aligned arrays of millimeter long carbon nanotubes (CNTs), from benzene and ferrocene as the molecular precursor and catalyst respectively, by a one-step chemical vapor deposition technique. The length of the grown CNTs depends on the reaction temperature and increases from ~85 µm to ~1.4 mm when the synthesis temperature is raised from 650 to 1100 °C, while the tube diameter is almost independent of the preparation temperature and is ~80 nm. The parallel arrangement of the CNTs, as well as their tube diameter can be verified spectroscopically by small angle X-ray scattering (SAXS) studies. Based on electron diffraction scattering (EDS) studies of the top and the base of the CNT films, a root growth process can be deduced.

In this paper, it is shown that a liquid-drop model (LDM) can predict the size-dependent cohesive energy (SDCE) of large nanoparticles and clusters (particles with few atoms) quantitatively. The cohesive energy decreases linearly with the inverse of the particle size both for large nanoparticles and clusters though the slopes are different. This indicates that there are three different regions (I-III) of SDCE in the complete size range. Regions I and II represent the SDCE of large nanoparticles and clusters, respectively, while region II represents the intermediate region where the cohesive energy is almost size-independent. Different regions of SDCE correspond to different structures of nanoparticles, and structural transition associated with the particle size can easily be predicted from the SDCE. Analyzing the cohesive energy data on the basis of LDM, it is shown that the surface tension decreases with decreasing size for very small nanoparticles. The Tolman equation can account for the variation of surface tension by predicting the size dependency of the Tolman length.

Treatment with gibberellic acid (GA3) causes formation of flowers in Panicum ciliaceum and Panicum miliare, two short-day plants, under long days (continuous light), and hastens the emergence of ears in Setaria italica, a quantitative short-day plant, under both inductive and non-inductive photoperiods. The GA3-induced inflorescences, however, remain short and bear only few spikelets; in the two Panicum species, the spikelets also remain sterile.

Adenosine monophosphates (AMPs) cause the induction of floral buds in Impatients balsamina L. under strictly non-inductive photoperiods and hasten it under inductive photoperiods, cyclic AMP being more effective than 3'- or 5'-AMPs in this regard.

The present paper deals with changes in the ascorbic acid content of the shoot apex during its transformation from the vegetative to the reproductive state and its further development in Panicum miliaceum var. Samai Co. 1. Seedlings were exposed to 24-hour illumination, natural day, and 8 hours of illumination per day. Ascorbic acid was determined for the growing apex, stem, and leaf of the main shoot and for the individual branches produced on it at successive developmental stages.A several-fold increase in ascorbic acid content of the growing apex of the main shoot of plants grown under 8-hour illumination synchronizes with its transformation from the vegetative to the reproductive state. In plants grown under natural day and continuous illumination, which continue to grow vegetatively, the ascorbic acid content remains at a low level. Moving these plants to 8-hour illumination results in floral initiation and an increase in the ascorbic acid content. The high level of ascorbic acid is maintained through the gametogenic and embryogenic phases, but decreases during seed formation. A rise in ascorbic acid content of branch apices always occurs later than that in the main shoot but the increase again coincides with floral initiation in the branch apex. The ascorbic acid contents of stem and leaf are not significantly affected by the photoperiod. Hence, a massive upsurge in ascorbic acid content synchronizes with the transformation of the vegetative branch and shoot apices to the reproductive state.

Treatment with gibberellic acid (GA3) enhances the number of adventitious roots and the number and length of sprouted buds on stem cuttings of Ipomoea fistulosa. Such simultaneous promotion of both rooting and sprouting is in contrast to most earlier reports on the effect of GA3 on these processes.

Seedlings of Impatiens balsamina raised under ND and LD conditions were divided into two sub-groups each when they had reached 5-leaf stage. While one sub-group was left under the same condition (NDND or LDLD), the other was transferred to the other photoperiod (NDLD or LDND). NDND plants were subdivided into 2 lots. One of these was transferred to SD in May. The dates of emergence of individual branches and floral buds were recorded and the vegetative period was calculated in each case.It was found that in NDND plants floral buds were produced from all the nodes except the lowermost which produced a single vegetative branch. In LDND plants the vegetative branches were produced from the lower 9 nodes but floral buds from those above these. Small leafy structures which ultimately dried up were produced from a few top nodes in both these cases. In contrast to this in LDLD plants only vegetative branches were produced from all the nodes. In NDLD plants floral buds were produced from the lower 3-5 nodes prior to transfer to LD condition, but vegetative branches were produced from the upper nodes after this transfer. Even some of the lower floral buds reverted to vegetative state under this condition.The production of floral buds or the vegetative branches as the case may be, occurred in acropetal succession under all the photoperiodic conditions and never in basipetal manner.LDLD and NDLD plants, which did not flower at all, continued to produce lateral branches without showing any sign of senescence, while LDND and NDND ones showed yellowing of the apical growing point which spread downwards and lead ultimately to the death of the plant. The senescence was hastened when these plants were transferred to SD condition towards the end of May. The senescence therefore, appears to be related with reproductive development. The results are discussed in the light of current literature.

The inductive effect of short-day (SD) cycles on floral-bud initiation in Impatiens balsamina was enhanced and the minimum requirement for SD cycles for flowering reduced by intercalated long days (LDs). Thus, floral buds developed into flowers with only 4 SD cycles in plants receiving them individually or in pairs alternating with LDs, but failed to develop in those receiving 4 SD sycles consecutively. The number of flowering plants increased while the periods to floral-bud initiation and flowering, calculated from the day of completion of 4 and 8 SD cycles, respectively, decreased with an increase in the number of intercalated LDs.

In the short-day plant Impatiens balsamina it was found that, while floral buds are initiated with 3 short-day (SD) cycles, at least 8 such cycles are required for flowering. The numbers of floral buds and open flowers bear a linear relationship with the number of SD cycles. The induced floral buds revert to vegetative growth unless the plants receive the minimum number of SD cycles needed for flowering, this reversion occurring in a basipetal direction. The rate of extension growth of the stem increases with increasing numbers of SD cycles. The high rate is maintained longer in plants receiving 32 or more SD cycles, but the subsequent fall is also steeper in these plants than in plants receiving less inductive cycles. Senescence also occurs in these plants and appears to be related to the magnitude of reproductive development and the high rate of extension growth.

Gibberellins A3, A4+7 and A13 and (-)-kaurene delay floral-bud initiation and flowering and decrease the number of floral-buds and flowers in Impatiens balsamina under 4-hr photoperiods. They do not have any marked effect under 8-hr photoperiods. Under 16- and 24-hr photoperiods they hasten floral-bud initiation and flowering and increase the number of flowers, the effect being greater under 16- than under 24-hr days and the order of effectiveness being GA4+7>GA3>GA13>(-)-kaurene.While GA3 and GA4+7 promote extension growth, the effect being greater with the former, GA13 and (-)-kaurene do not promote it under any photoperiod. The magnitude of stem elongation in different treatments prior to floral-bud initiation increases from 4- to 8-hr photoperiods but decreases under 16- and 24-hr periods, the effect being more under 24-hr although both 16-and 24-hr photoperiods are noninductive for flowering.

In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants.

Floral buds were initiated in Impatiens balsamina plants treated with 2,3,5-triiodobenzoic acid (TIBA) and kept under non-inductive 16- and 24-hr photoperiods, although much later than under inductive 8-hr photoperiods. TIBA did not affect extension growth to any appreciable extent but decreased the number of nodes on the main shoot under 8-hr and increased it under 16- and 24-hr photoperiods. Its effect on the development of lateral buds varied with photoperiod. TIBA-induced flowering resembles gibberellin-induced one, but its mechanism is not clear.