Demographic and Clinical Characteristics of Functional Dyspepsia and Its Subtypes in Adult Patients: An Experience from a Tertiary Care Centre in Bangladesh

Functional dyspepsia (FD) is a common gastrointestinal problem in the world. The Rome III consensus subdivided functional dyspepsia into two groups: meal-related postprandial distress syndrome (PDS) and meal-unrelated epigastric pain syndrome (EPS). Limited data are available regarding FD in Bangladesh. The aim of this study was to investigate the demographic and clinical characteristics of FD and its sub-types. This cross-sectional study was conducted in which we recruited patients who attended the outpatient department of Gastroenterology of Bangabandhu Sheikh Mujib Medical University, Bangladesh from March 2017 to February 2018. Patients fulfilling Rome III FD criteria and a negative upper GIT endoscopy were included for this study. The patients were then subdivided into 'pure' PDS (i.e. meeting criteria for PDS without EPS symptoms), 'pure' EPS (i.e., meeting criteria for EPS without PDS symptoms), and overlapping PDS-EPS (i.e., symptoms of both PDS and EPS) groups. Total of 368 FD patients (56.0% females, mean age 32.8±8.6 years, BMI: 22.0±2.7), were included in this study. Out of them, 112(30.4%) patients (57.2% females, mean age 33.9±9.3 years, BMI: 22.0±2.7) fulfilled criteria of pure EPS and 64(17.4%) patients (68.8% females, mean age 33.2±7.8 years, BMI: 22.1±2.4) fulfilled criteria of pure PDS. However, the majority of patients [192(52.2%), 52.1% females, mean age 32.0±8.4 years, BMI: 21.9±2.8] had symptoms of overlapping EPS-PDS. More than 40% of patients in our study presented with 3 or more of the four key symptoms of FD. A longer duration of presenting symptoms was seen among patients with overlapping EPS-PDS in comparison to pure EPS and pure PDS (p<0.001). A significant overlap of symptoms of both EPS and PDS was noticed among patients with FD. The value of dividing functional dyspepsia into the subgroups of PDS and EPS is thus questionable. Further research and modification of the diagnostic criteria for FD subtypes are necessary.

Homeopathic Medicines in Third (Omicron) Wave of COVID-19: Prognostic Factor Research

BACKGROUND

 With the emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, such as the Omicron variant, during the third wave of the coronavirus disease 2019 (COVID-19) pandemic, there was a need to identify useful homeopathic medicines. This study aimed to identify such medicines and their indications using prognostic factor research (PFR).

METHODS

 This was an open-label, multi-centred observational study conducted in January 2022, on confirmed COVID-19 cases. The data were collected from integrated COVID Care Centres in Delhi, India, where homeopathic medicines were prescribed along with conventional treatment. Only those cases that met a set of selection criteria were considered for analysis. The likelihood ratio (LR) was calculated for the frequently occurring symptoms of the frequently prescribed medicines. An LR of 1.3 or greater was considered meaningful.

RESULTS

 Out of the 362 COVID-19 cases, 263 cases were selected for analysis after applying selection criteria. Common symptoms included fatigue, cough, sore throat, myalgia and headache. Twenty-one medicines were prescribed, of which nine medicines - Gelsemium sempervirens, Bryonia alba, Hepar sulphuris, Rhus toxicodendron, Pulsatilla nigricans, Arsenicum album, Belladonna, Nux vomica and Phosphorus - were frequently used. By calculating LRs, the study identified meaningful indications for these medicines.

CONCLUSION

 Homeopathic medicines have shown promising results in the third wave of COVID-19 as an adjunct therapy. The medicines that were used in the first and second waves were found useful in the third wave also, and their indications were analogous to those found in the earlier waves. Certain new indications of some medicines were elicited in this wave, which warrant further research. However, it is important not to restrict to these medicines only and to continue data collection on COVID-19 in future waves for the improvement of the COVID-19 mini-repertory.

Atomic-layered V2C MXene containing bismuth elements: 2D/0D and 2D/2D nanoarchitectonics for hydrogen evolution and nitrogen reduction reaction

The exploitation of two-dimensional (2D) vanadium carbide (V₂CT_x, denoted as V₂C) in electrocatalytic hydrogen evolution reaction (HER) and nitrogen reduction reaction (NRR) is still in the stage of theoretical study with limited experimental exploration. Here, we present the experimental studies of V₂C MXene-based materials containing two different bismuth compounds to confirm the possibility of using V₂C as a potential electrocatalyst for HER and NRR. In this context, for the first time, we employed two different methods to synthesize 2D/0D and 2D/2D nanostructures. The 2D/2D V₂C/BVO consisted of BiVO₄ (denoted BVO) nanosheets wrapped in layers of V₂C which were synthesized by a facile hydrothermal method, whereas the 2D/0D V₂C/Bi consisted of spherical particles of Bi (Bi NPs) anchored on V₂C MXenes using the solid-state annealing method. The resultant V₂C/BVO catalyst was proven to be beneficial for HER in 0.5 M H₂SO₄ compared to pristine V₂C. We demonstrated that the 2D/2D V₂C/BVO structure can favor the higher specific surface area, exposure of more accessible catalytic active sites, and promote electron transfer which can be responsible for optimizing the HER activity. Moreover, V₂C/BVO has superior stability in an acidic environment. Whilst we observed that the 2D/0D V₂C/Bi could be highly efficient for electrocatalytic NRR purposes. Our results show that the ammonia (NH₃) production and faradaic efficiency (FE) of V₂C/Bi can reach 88.6 μg h^-1 cm^-2 and 8% at -0.5 V vs. RHE, respectively. Also V₂C/Bi exhibited excellent long-term stability. These achievements present a high performance in terms of the highest generated NH₃ compared to recent investigations of MXenes-based electrocatalysts. Such excellent NRR of V₂C/Bi activity can be attributed to the effective suppression of HER which is the main competitive reaction of the NRR.

Hydrogen-Terminated Two-Dimensional Germanane/Silicane Alloys as Self-Powered Photodetectors and Sensors

2D monoelemental materials, particularly germanene and silicene (the single layer of germanium and silicon), which are the base materials for modern electronic devices demonstrated tremendous attraction for their 2D layer structure along with the tuneable electronics and optical band gap. The major shortcoming of synthesized thermodynamically very unstable layered germanene and silicene with their inclination toward oxidation was overcome by topochemical deintercalation of a Zintl phase (CaGe₂, CaGe_1.5Si_0.5, and CaGeSi) in a protic environment. The exfoliated Ge-H, Ge_0.75Si_0.25H, and Ge_0.5Si_0.5H were successfully synthesized and employed as the active layer for photoelectrochemical photodetectors, which showed broad response (420-940 nm), unprecedented responsivity, and detectivity on the order of 168 μA W^-1 and 3.45 × 10⁸ cm Hz^1/2 W^-1, respectively. The sensing capability of exfoliated germanane and silicane composites was explored using electrochemical impedance spectroscopy with ultrafast response and recovery time of less than 1 s. These positive findings serve as the application of exfoliated germanene and silicene composites and can pave a new path to practical applications in efficient future devices.

A facile and green synthesis of Mn and P functionalized graphitic carbon nitride nanosheets for spintronics devices and enhanced photocatalytic performance under visible-light

Manganese and phosphorus co-doped, graphitic carbon nitride (g-C₃N₄) nanosheet (Mn/P-g-C₃N₄) is prepared by facile and green calcination process of melamine (C₃H₆N₆), manganese chloride tetrahydrate (MnCl₂·4H₂O), and ammonium dihydrogen phosphate ((NH₄)H₂PO₄). The Mn/P co-doping significantly enhances magnetic values compared to pristine-g-C₃N₄, phosphorus-doped g-C₃N₄ (P-g-C₃N₄), and manganese-doped g-C₃N₄ (Mn-g-C₃N₄). We find that Mn/P-g-C₃N₄ is a half-metallic ferromagnetic material having a magnetic moment and Curie temperature of 4.51 μ_B and ∼ 800 K, respectively. The ultraviolet-visible (UV-vis) absorption spectrum of Mn/P-g-C₃N₄ reveals superior absorption in broader wavelength compared to pristine-g-C₃N₄, P-g-C₃N₄, and Mn-g-C₃N₄. The methyl orange degradation efficiency of Mn/P-g-C₃N₄ photocatalyst is 94 %, which is three times more than that of pristine-g-C₃N₄ (29 %) and more significant than the P-g-C₃N₄ (46 %) and Mn-g-C₃N₄ (58 %). Furthermore, density functional theory (DFT) calculation explains the origin of high magnetic behavior, the boosted photocatalytic efficiency of Mn/P-g-C₃N₄, and the essential material properties like structure, bandgap, the density of states (DOS), and atomic level interaction. This work may be helpful for reasonably designing ferromagnetic material for spintronics devices and boosting visible-light (VL) photocatalytic performance for environmental remediation.

One-Step Electrochemical Synthesis of AlO x -Passivated Twisted-Phosphorene Nanosheets for Potentially Stable Energy Storage Devices

Black phosphorus (BP), a promising 2D material for electronics, energy storage, catalysis, and sensing, has sparked a research boom. However, exfoliated thin-layered BP is unstable and can easily be degraded under environmental conditions, severely limiting its practical applications. In this context, a simple and cost-effective method has been proposed that involves electrochemically exfoliating BP and simultaneously electrochemically depositing aluminum oxide (AlO _x ) for passivation of the exfoliated BP. The ambient stability of the exfoliated BP is studied using a time-dependent atomic force microscope (AFM). The AlO _x capping layer significantly improves the environmental stability of BP compared to uncapped BP. The thermal stability of the resulting BP is evaluated using power-dependent Raman spectroscopy. The results show that the AlO _x -passivated BP has increased thermal stability, with only a slight shift in peak position toward higher Raman power intensity. These properties can make the material suitable for stable energy storage devices. Interestingly, the electrochemical exfoliation and passivation processes resulted in the BP with a twist angle (9.86°), which is expected to exhibit unique electronic properties similar to those of graphene with a twist angle.

A New, Thorough Look on Unusual and Neglected Group III-VI Compounds Toward Novel Perusals

The attention on group III-VI compounds in the last decades has been centered on the optoelectronic properties of indium and gallium chalcogenides. These outstanding properties are leading to novel advancements in terms of fundamental and applied science. One of the advantages of these compounds is to present laminated structures, which can be exfoliated down to monolayers. Despite the large knowledge gathered toward indium and gallium chalcogenides, the family of the group III-VI compounds embraces several other noncommon compounds formed by the other group III elements. These compounds present various crystal lattices, among which a great deal is offered from layered structures. Studies on aluminium chalcogenides show interesting potential as anodes in batteries and as semiconductors. Thallium (Tl), which is commonly present in the +1 oxidation state, is one of the key components in ternary chalcogenides. However, binary Tl-Q (Q = S, Se, Te) systems and derived films are still studied for their semiconducting and thermoelectric properties. This review aims to summarize the biggest features of these unusual materials and to shed some new light on them with the perspective that in the future, novel studies can revive these compounds in order to give rise to a new generation of technology.

Synthesis and characterization of titanium-substituted nanocrystalline Co2-Y hexaferrite: magnetically retrievable photocatalyst for treatment of methyl orange contaminated wastewater

Rapid industrial growth causes considerable environmental havoc, adversely affecting human and aqueous life. It becomes a significant concern to deal with adequate wastewater treatment strategies by converging on water scarcity. This research work explored the synthesis of titanium-substituted Y-type barium hexaferrite (Co₂-Y), having a general formula of Ba₂Co₂Fe_12-xTi_xO₂₂ (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5), using a facile nitrate-based sol-gel auto-combustion route and its suitability was investigated as a heterogeneous catalyst within the photo-Fenton-based degradation of methyl orange (MO), one of the significant pollutants generated from textile industries. Developing a thermochemically stable and magnetically separable heterogeneous catalyst for photocatalytic decomposition of nonbiodegradable organic dye from wastewater was also emphasized. The as-prepared nanocrystalline Co₂-Y powders were analyzed using XRD, FTIR, DLS, UV-visible spectroscopy, SEM, VSM, and XPS. Furthermore, the photocatalytic degradation performance of pristine and titanium substituted Ba₂Co₂Fe_11.6Ti_0.4O₂₂ ferrite, having the lowest bandgap value among all samples, was quantified and compared in terms of apparent rate constant (k_arc) value and turnover frequency values. The enriched photocatalytic performance was correlated with the existence of multi-valance states of transition metal cations and the availability of oxygen vacancy, confirmed by the surface chemistry using the XPS analysis. The modified (enhanced thermal and chemical stability) hexaferrite catalyst was magnetically separable and reusable without significant losses to its catalytic performance. This promising catalyst may be considered as a replacement for soft ferrite materials to catalyze the degradation of several other nonbiodegradable organic pollutants from wastewater in large-scale industries.

Chalcogen (S, Se, and Te) decorated few-layered Ti3C2Tx MXene hybrids: modulation of properties through covalent bonding

2D carbides and nitrides of transition metals (MXenes) have shown great promise in a variety of energy storage and energy conversion applications. The extraordinary properties of MXenes are because of their excellent conductivity, large carrier concentration, vast specific surface area, superior hydrophilicity, high volumetric capacitance, and rich surface chemistry. However, it is still desired to synthesize MXenes with specific functional groups that deliver the required characteristics. This is due to the fact that a considerable amount of metal atoms is exposed on the surface of MXenes during their synthesis through an etching procedure; hence, other anions and cations are uncontrollably implanted on their surfaces. Because of this situation, the first invented Ti₃C₂T_x MXene suffers from low photoresponsivity and detectivity, large overpotential, and small sensitivity in photoelectrochemical (PEC) photodetectors, hydrogen evolution reaction (HER), and sensing applications. Therefore, surface modification of the MXene structure is required to develop the device's performance. On the other hand, there is still a lack of understanding of the MXene mechanism in such cutting-edge applications. Thus, the manipulations of MXenes are highly dependent on understanding the device mechanism, suitable modification elements, and modification methods. This study for the first time reveals the conjugation effect of pre-selected S, Se, and Te chalcogen elements on a few-layered Ti₃C₂T_x MXene to synthesize new composites for PEC photodetector, HER, and vapor sensor applications. Also, the mechanism of the chalcogen decorated few-layered Ti₃C₂T_x MXene composites for each application is discussed. The selection of a few-layered Ti₃C₂T_x MXene is due to its fascinating characteristics which make it capable to be considered as an appropriate substrate and incorporating chalcogen atoms. The Te-decorated few-layered Ti₃C₂T_x MXene composite provides better performances in PEC photodetector and vapor sensing applications. Although the potential value of the Se-decorated few-layered Ti₃C₂T_x composite is slightly lower than that of the Te-decorated sample in HER application, its overpotential is still greater than that of the Te-decorated sample. The acquired results show that the S-decorated few-layered Ti₃C₂T_x composite demonstrates the lowest performance in all three examined applications in comparison with the other two samples.

2D Few-Layered PdPS: Toward High-Efficient Self-Powered Broadband Photodetector and Sensors

Photodetectors and sensors have a prominent role in our lives and cover a wide range of applications, including intelligent systems and the detection of harmful and toxic elements. Although there have been several studies in this direction, their practical applications have been hindered by slow response and low responsiveness. To overcome these problems, we have presented here a self-powered (photoelectrochemical, PEC), ultrasensitive, and ultrafast photodetector platform. For this purpose, a novel few-layered palladium-phosphorus-sulfur (PdPS) was fabricated by shear exfoliation for effective photodetection as a practical assessment. The characterization of this self-powered broadband photodetector demonstrated superior responsivity and specific detectivity in the order of 33 mA W^-1 and 9.87 × 10¹⁰ cm Hz^1/2 W^-1, respectively. The PEC photodetector also exhibits a broadband photodetection capability ranging from UV to IR spectrum, with the ultrafast response (∼40 ms) and recovery time (∼50 ms). In addition, the novel few-layered PdPS showed superior sensing ability to organic vapors with ultrafast response and a recovery time of less than 1 s. Finally, the photocatalytic activity in the form of hydrogen evolution reaction was explored due to the suitable band alignment and pronounced light absorption capability. The self-powered sensing platforms and superior catalytic activity will pave the way for practical applications in efficient future devices.

Self-Powered Broadband Photodetector and Sensor Based on Novel Few-Layered Pd3(PS4)2 Nanosheets

Optoelectronics and sensing devices are of enormous importance in our modern lives, which has propelled the scientific community to explore new two-dimensional (2D) nanomaterials to meet the requirements of future devices. Herein, we present the exfoliation of palladium thiophosphate (Pd₃(PS₄)₂) by mechanical shear force exfoliation. The Pd₃(PS₄)₂-based photoelectrochemical (PEC) device demonstrated self-powered broadband photodetection in the range of 385-940 nm with an unprecedented responsivity of 2 A W^-1 and a specific detectivity of about 8.67 × 10¹¹ cm Hz^1/2 W^-1 under the illumination of 420 nm LED light. The crucial parameters such as photoresponsivity, response, and recovery time of the device can be controlled by an externally applied voltage and the analyte concentration. Moreover, Pd₃(PS₄)₂-based vapor-sensing devices exhibited frequency-dependent selective acetone sensing in the presence of other organic vapors with an ultrafast response and a recovery time of less than 1 s. Finally, the photocatalytic activity of Pd₃(PS₄)₂ was revealed, which can be attributed to the presence of an appropriate band alignment with the catalytic activity of Pd. This novel material with the aforementioned fascinating phenomenon will pave the way toward practical future applications in optoelectronics and sensing.

Exfoliated two-dimensional molybdenum disulfide reinforced epoxy syntactic foams

In this paper, we report the effect of introducing molybdenum disulfide (MoS2) nano-platelets: a two-dimensional metal chalcogenide, on the mechanical properties of hollow glass microballoon (HGM)–epoxy syntactic foams. MoS2 reinforced syntactic foams were prepared by mixing MoS2 nanoplatelets to epoxy containing HGMs; with the amount of MoS2 being varied from 0.01 to 0.04% v/v, while maintaining a constant total filler volume fraction of 40% for all compositions. The mechanical behaviour of reinforced syntactic foam was studied under varied loadings including compressive, tensile and flexural under different strain rate regimes. Introduction of MoS2 led to significant improvements in characteristic mechanical properties, particularly in terms of compressive strength and toughness, which suggest intercalation of MoS2 within the epoxy matrix; however, the presence of relatively larger MoS2 micro particles couldn’t be completely negated. The toughness of the foam, as indicated by the area under the compressive stress-strain curve, was found to increase by ∼21% under optimal conditions. Our results highlight the potential of the two-dimensional MoS2 sheets as a reinforcing agent in syntactic foams.

Study of thyroid function in pregnancy, its feto-maternal outcome; a prospective observational study

Background

Pregnancy is a stress test of maternal thyroid function. The prevalence of thyroid dysfunction in pregnant women is high. Subclinical hypothyroidism occurs in 10% of all pregnancies. Effects of hypothyroidism in pregnancy are anemia, low birth weight and mental retardation in neonate. This study is aimed to evaluate maternal and fetal outcomes in pregnant women with deranged thyroid profile. The relevance of this study is to document the association of hypothyroidism and its adverse effects on mother and fetus.

Methods

This prospective observational study was carried out at R.D. Gardi Medical College, Ujjain, India. Subjects of this study were 198 antenatal women in third trimester with singleton pregnancy admitted in the obstetric ward, and informed consent was obtained. Women were chosen irrespective of age, parity, residence and socioeconomic status. Women with multiple pregnancy, a known case of thyroid disorder, or any pre-existing medical disorder were excluded. Routine hematological parameters and estimation of T3, T4 and TSH was conducted. Patients with deranged thyroid profile were subsequently assessed for maternal and fetal complications. History of infertility, family history of thyroid disease, menstrual pattern, recurrent abortion, hemoglobin level and fetal outcome were the main study variables. Data was analysed in SPSS software for statistical co-relation.

Results

Prevalence of thyroid disorder is 11%; with subclinical hypothyroidism, overt hypothyroidism and subclinical hyperthyroidism occurring in 5.6, 3.5 and 1.5% of subjects respectively. In women with subclinical and overt hypothyroidism, anemia was present in 26.3% being significantly associated with hypothyroidism (p = 0.008). With respect to fetal outcome, LBW 31.6% (p = 0.001), NICU admission 42.1%, (p = 0.000) and low APGAR Score (21.1%, p = 0.042) were statistically associated with hypothyroidism. Risk of anemia, Low Birth weight, NICU admissions, and low APGAR score was 4.8, 6.3, 0.14 and 3.64 times higher respectively in women with hypothyroidism than in women who are euthyroid.

Conclusion

Prevalence of subclinical hypothyroidism is 5.6% in 3rd trimester of pregnancy. Anemia, pre-eclampsia, high caesarean rates and neonatal morbidities is significantly associated with hypothyroidism.

Single-Step Synthesis of Platinoid-Decorated Phosphorene: Perspectives for Catalysis, Gas Sensing, and Energy Storage

The originality of phosphorene is suppressed by its structural defects, irreproducibility, and sensitivity to the ambient environment. To preserve phosphorene's essential characteristics, for example, influencing the charge redistribution and generating the formation of active centers, noble-metal decoration is found to be an efficient approach. Herein, we demonstrate a single-step electrochemical synthesis of platinoid-decorated few-layer phosphorene (FP). The material's structure and effects of metal (Ru, Rh, and Pd) deposition on the FP nanosheets were first explored by numerous analytical techniques and theoretical calculations. Platinoid-decorated FPs demonstrate high quality and consist of one to five layers modified with round- and heptagon-shaped metal nanoparticles with the most intense distribution of Pd. The high-rate Rh deposition provides the enhanced electrocatalytic efficiency for hydrogen evolution (79 mV·dec^-1-Tafel slope) and almost 20 times increased capacity for the Li-ion batteries in comparison to bare and Ru-decorated FP. The chemosensing of platinoid-decorated FP indicates a response to methanol plus ethanol and shows inertness to acetone. The incorporation of Ru and Rh nanoparticles increases FP's selectivity toward methanol. This research provides a new approach for the in situ FP functionalization during top-down synthesis and thus broadens the material's feasibility for advanced nanotechnology.

Unprecedented random lasing in 2D organolead halide single-crystalline perovskite microrods

Three-dimensional organic-inorganic hybrid halide perovskites have been demonstrated as great materials for applications in optoelectronics and photonics. However, their inherent instabilities in the presence of moisture, light, and heat may hinder their commercialization. Alternatively, emerging two-dimensional (2D) organic-inorganic hybrid perovskites have recently attracted increasing attention owing to their great environmental stability and inherent natural quantum-well structure. In this work, we have synthesized a high-quality long-chain organic diammonium spacer assisted 2D hybrid perovskite FA-(N-MPDA)PbBr₄ (FA = formamidinium and N-MPDA = N-methylpropane-1,3-diammonium) by the slow evaporation at constant temperature method. The millimeter-sized single-crystalline microrods demonstrate low threshold random lasing behavior at room temperature. The single-crystalline 2D hybrid perovskite random laser achieved a very narrow linewidth (∼0.1 nm) with a low threshold (∼0.5 μJ cm^-2) and a high quality factor (∼5350). Furthermore, the 2D hybrid microrod laser shows stable lasing emission with no measurable degradation after at least 2 h under continuous illumination, which substantially proves the stability of 2D perovskites. Our results demonstrate the promise of 2D organic-inorganic microrod-shaped perovskites and provide an important step toward the realization of high-performance optoelectronic devices.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M_{⊙}

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21}  M_{⊙} and 66_{-18}^{+17}  M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65  M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28}  M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4}  Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30}  Gpc^{-3} yr^{-1}.

Ultralow Threshold Cavity-Free Laser Induced by Total Internal Reflection

Total internal reflection is one of the most important phenomena when a propagated wave strikes a medium boundary, which possesses a wide range of applications spanning from optical communication to a fluorescence microscope. It has also been widely used to demonstrate conventional laser actions with resonant cavities. Recently, cavity-free stimulated emission of radiation has attracted great attention in disordered media because of several exciting physical phenomena, ranging from Anderson localization of light to speckle-free imaging. However, unlike conventional laser systems, the total internal reflection has never been implemented in the study of laser actions derived from randomly distributed media. Herein, we demonstrate an ultra-low threshold cavity-free laser system using air bubbles as scattering centers in which the total internal reflection from the surface of air bubbles can greatly reduce the leakage of the scattered beam energy and then enhance light amplification within a coherent closed loop. Our approach provides an excellent alternative for the manipulation of optical energy flow to achieve ultra-low threshold cavity-free laser systems, which should be very useful for the development of high performance optoelectronic devices.

Microplasma-Enabled Graphene Quantum Dot-Wrapped Gold Nanoparticles with Synergistic Enhancement for Broad Band Photodetection

Plasmonic nanostructure/semiconductor nanohybrids offer many opportunities for emerging electronic and optoelectronic device applications because of their unique geometries in the nanometer scale and material properties. However, the development of a simple and scalable synthesis of plasmonic nanostructure/semiconductor nanohybrids is still lacking. Here, we report a direct synthesis of colloidal gold nanoparticle/graphene quantum dot (Au@GQD) nanohybrids under ambient conditions using microplasmas and their application as photoabsorbers for broad band photodetectors (PDs). Due to the unique AuNP core and graphene shell nanostructures in the synthesized Au@GQD nanohybrids, the plasmonic absorption of the AuNP core extends the usable spectral range of the photodetectors. It is demonstrated that the Au@GQD-based visible light photodetector simultaneously possesses an extraordinary photoresponsivity of ∼10³ A/W, ultrahigh detectivity of 10¹³ Jones, and fast response time in the millisecond scale (65 ms rise time and 53 ms fall time). We suggest that the synergistic effect can be attributed to the strong fluorescence quenching in Au@GQD coupled with the two-dimensional graphene layer in the device. This work provides knowledge of tailoring the optical absorption in GQDs with plasmonic AuNPs and the corresponding photophysics for broad band response in PD-related devices.

Emerging pnictogen-based 2D semiconductors: sensing and electronic devices

Pnictogens are an intensively studied group of monoelemental two-dimensional materials. This group of elements consists of phosphorus, arsenic, antimony, and bismuth. In this group, the elements adopt two different layered structural allotropes, orthorhombic structure with true van der Waals layered interactions and rhombohedral structure, where covalent interactions between layers are also present. The orthorhombic structure is well known for phosphorus and arsenic, and the rhombohedral structure is the most thermodynamically stable allotropic modification of arsenic, antimony, and bismuth. Due to the electronic structure of pnictogen layers and their semiconducting character, these materials have huge application potential for electronic devices such as transistors and sensors including photosensitive devices as well as gas and electrochemical sensors. While photodetection and gas sensing applications are often related to lithography processed materials, chemical sensing proceeds in a liquid environment (either aqueous or non-aqueous) and can be influenced by surface oxidation of these materials. In this review, we explore the current state of pnictogen applications in sensing and electronic devices including transistors, photodetectors, gas sensors, and chemical/electrochemical sensors.

Graphene Sandwich Stable Perovskite Quantum-Dot Light-Emissive Ultrasensitive and Ultrafast Broadband Vertical Phototransistors

Dual-functional devices that can simultaneously detect light and emit light have a tremendous appeal for multiple applications, including displays, sensors, defense, and high-speed optical communication. Despite the tremendous efforts of scientists, the progress of integration of a phototransistor, where the built-in electric field separates the photogenerated excitons, and a light-emitting diode, where the radiative recombination can be enhanced by band offset, into a single device remains a challenge. Combining the superior properties of perovskite quantum dots (PQDs) and graphene, here we report a light-emissive, ultrasensitive, ultrafast, and broadband vertical phototransistor that can simultaneously act as an efficient photodetector and light emitter within a single device. The estimated value of the external quantum efficiency of the vertical phototransistor is ∼1.2 × 10¹⁰% with a photoresponsivity of >10⁹ A W^-1 and a response time of <50 μs, which exceed all the presently reported vertical phototransistor devices. We also demonstrate that the modulation of the Dirac point of graphene efficiently tunes both amplitude and polarity of the photocurrent. The device exhibits a green emission having a quantum efficiency of 5.6%. The moisture-insensitive and environmentally stable, light-emissive, ultrafast, and ultrasensitive broadband phototransistor creates a useful route for dual-functional optoelectronic devices.

Ultrasensitive Gas Sensors Based on Vertical Graphene Nanowalls/SiC/Si Heterostructure

Gas sensors, which play an important role in the safety of human life, cover a wide range of applications including intelligent systems and detection of harmful and toxic gases. It is known that graphene is an ideal and attractive candidate for gas sensing due to its high surface area and excellent mechanical, electrical, optical, and thermal properties. However, in order to fully realize its potential as a commercial gas sensor, demand for a graphene-based device of low-limit detection, high sensitivity, and fast response time needs to be met. Here, we demonstrate a metal/insulator/semiconductor (MIS) based gas sensor consisting of as-grown epitaxial graphene nanowalls (EGNWs)/silicon carbide (SiC)/silicon (Si) structure. The unique edge dominant three-dimensional (3D) EGNWs based MIS device achieved an extraordinarily low limit of detection (0.5 ppm) and unprecedented sensitivity (82 μA/ppm/cm² for H₂) with a fast response of shorter than 500 ms. These unique properties of our MIS device are attributed to the abundance of vertically oriented nanographitic edges and structural defects that act as extra-favorable adsorption sites and exhibit fast electron-transfer kinetics through the edges. Our experimental findings can pave the way for the realization of high-performance 3D graphene-based gas sensor devices.

Nanoscale Core-Shell Hyperbolic Structures for Ultralow Threshold Laser Action: An Efficient Platform for the Enhancement of Optical Manipulation

Plasmonic material has emerged with multifunctionalities for its remarkable tailoring light emission, reshaping density of states (DOS), and focusing subwavelength light. However, restricted by its propagation loss and narrowband resonance in nature, it is a challenge for plasmonic material to provide a broadband DOS to advance its application. Here, we develop a novel nanoscale core-shell hyperbolic structure that possesses a remarkable coupling effect inside the multishell nanoscale composite owing to a higher DOS and a longer time of collective oscillations of the electrons than the plasmonic-based pure-metal nanoparticles. Subsequently, a giant localized electromagnetic wave of surface plasmon resonance is formed at the surface, causing pronounced out-coupling effect. Specifically, the nanoscale core-shell hyperbolic structure confines the energy well without being decayed, reducing the propagation loss and then achieving an unprecedented stimulated emission (random lasing action by dye molecule) with a record ultralow threshold (∼30 μJ/cm²). Besides, owing to the radial symmetry of the nanoscale core-shell hyperbolic structure, the excitation of high wavevector modes and induced additional DOS are easily accessible. We believe that the nanoscale core-shell hyperbolic structure paves a way to enlarge the development of plasmonic-based applications, such as high optoelectronic conversion efficiency of solar cells, great power extraction of light-emitting diodes, wide spectra photodetectors, carrying the emitter inside the core part as quantitative fluorescence microscopy and bioluminescence imaging system for in vivo and in vitro research on human body.

Evaluation of Duodenal Eosinophil Count in Adult Patients with Functional Dyspepsia

Several mechanisms have been proposed to explain the symptoms of functional dyspepsia but actual pathogenesis is still poorly understood. Recent studies support duodenal abnormality to be the most important causal link to explain symptoms and to understand abnormal pathophysiology of functional dyspepsia. The aim of this prospective observational study is to compare eosinophil count in duodenal mucosa between patients with functional dyspepsia and control subjects without dyspepsia and was done at the department of Gastroenterology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh from December 2015 to December 2016. Total 42 patients of functional dyspepsia based on Bangla validated version of ROME III criteria and 42 controls who were referred for upper gastrointestinal endoscopy for reasons other than dyspepsia were included. Biopsy specimens were collected from the second part (D2) of the duodenum of all participants. Eosinophil count was quantitatively evaluated by hematoxylin and eosin staining and expressed in numbers per 5 HPF. Significantly increased duodenal eosinophil count was found in functional dyspepsia group than non dyspeptic patients (22.78±08.78 vs. 14.90±10.70, p=0.001). Higher duodenal eosinophil count was found in patients with postprandial distress syndrome. Increased duodenal eosinophil count was found in patient of functional dyspepsia. It requires further large scale multicenter studies to establish duodenal eosinophilia as a biomarker of functional dyspepsia.

A Highly-Efficient Single Segment White Random Laser

Production of multicolor or multiple wavelength lasers over the full visible-color spectrum from a single chip device has widespread applications, such as superbright solid-state lighting, color laser displays, light-based version of Wi-Fi (Li-Fi), and bioimaging, etc. However, designing such lasing devices remains a challenging issue owing to the material requirements for producing multicolor emissions and sophisticated design for producing laser action. Here we demonstrate a simple design and highly efficient single segment white random laser based on solution-processed NaYF₄:Yb/Er/Tm@NaYF₄:Eu core-shell nanoparticles assisted by Au/MoO₃ multilayer hyperbolic meta-materials. The multicolor lasing emitted from core-shell nanoparticles covering the red, green, and blue, simultaneously, can be greatly enhanced by the high photonic density of states with a suitable design of hyperbolic meta-materials, which enables decreasing the energy consumption of photon propagation. As a result, the energy upconversion emission is enhanced by ∼50 times with a drastic reduction of the lasing threshold. The multiple scatterings arising from the inherent nature of the disordered nanoparticle matrix provide a convenient way for the formation of closed feedback loops, which is beneficial for the coherent laser action. The experimental results were supported by the electromagnetic simulations derived from the finite-difference time-domain (FDTD) method. The approach shown here can greatly simplify the design of laser structures with color-tunable emissions, which can be extended to many other material systems. Together with the characteristics of angle free laser action, our device provides a promising solution toward the realization of many laser-based practical applications.

Bimatoprost in Dermatology

Bimatoprost is a prostamide analogue used for treatment of glaucoma in ophthalmology. Surprisingly, the side effects such as increased pigmentation of eyelids and hypertrichosis in patients being treated with prostaglandin analogues for glaucoma have opened new areas of application in various dermatological disorders such as alopecia mainly affecting eyelashes, eyebrows, and vitiligo.

Wrinkled 2D Materials: A Versatile Platform for Low-Threshold Stretchable Random Lasers

A stretchable, flexible, and bendable random laser system capable of lasing in a wide range of spectrum will have many potential applications in next- generation technologies, such as visible-spectrum communication, superbright solid-state lighting, biomedical studies, fluorescence, etc. However, producing an appropriate cavity for such a wide spectral range remains a challenge owing to the rigidity of the resonator for the generation of coherent loops. 2D materials with wrinkled structures exhibit superior advantages of high stretchability and a suitable matrix for photon trapping in between the hill and valley geometries compared to their flat counterparts. Here, the intriguing functionalities of wrinkled reduced graphene oxide, single-layer graphene, and few-layer hexagonal boron nitride, respectively, are utilized to design highly stretchable and wearable random laser devices with ultralow threshold. Using methyl-ammonium lead bromide perovskite nanocrystals (PNC) to illustrate the working principle, the lasing threshold is found to be ≈10 µJ cm^-2 , about two times less than the lowest value ever reported. In addition to PNC, it is demonstrated that the output lasing wavelength can be tuned using different active materials such as semiconductor quantum dots. Thus, this study is very useful for the future development of high-performance wearable optoelectronic devices.

Dirac point induced ultralow-threshold laser and giant optoelectronic quantum oscillations in graphene-based heterojunctions

The occurrence of zero effective mass of electrons at the vicinity of the Dirac point is expected to create new paradigms for scientific research and technological applications, but the related discoveries are rather limited. Here, we demonstrate that a simple architecture composed of graphene quantum dots sandwiched by graphene layers can exhibit several intriguing features, including the Dirac point induced ultralow-threshold laser, giant peak-to-valley ratio (PVR) with ultra-narrow spectra of negative differential resistance and quantum oscillations of current as well as light emission intensity. In particular, the threshold of only 12.4 nA cm⁻² is the lowest value ever reported on electrically driven lasers, and the PVR value of more than 100 also sets the highest record compared with all available reports on graphene-based devices. We show that all these intriguing phenomena can be interpreted based on the unique band structures of graphene quantum dots and graphene as well as resonant quantum tunneling.

In graphene, electrons possess zero effective mass in proximity to the Dirac point, an unusual feature that could trigger the development of novel photonic devices. Here, the authors combine graphene quantum dots with two graphene layers and observe laser action with ultralow threshold.

Dermoscopy of alopecia areata-a retrospective analysis

Background

Dermoscopy devices can overcome the refractive properties of stratum corneum by interface medium or cross polarization such that the lesion can be easily seen.

Aim

To examine the dermoscopic feature in alopecia areata and correlate the severity of disease with dermoscopic features.

Materials and methods

Retrospective analysis of 72 patients suffering from alopecia areata (AA), irrespective of age and sex, who visited the dermatology outpatient department of a tertiary care center in Eastern India was carried out. The most recently developed cases of AA were examined dermoscopically. Variables included yellow dots (YDs), black dots (BDs), broken hair (BH), short vellus hair (SVH), and exclamation mark hair (EMH) on the basis of available literature and expertise.

Results

Yellow dots was the most common finding seen in 57 cases (79.16%), black dots in 51 cases (70.8%). Short vellus hair was seen in 32 cases (44.44%), broken hair was seen in 31 cases (43.05%), and exclamation mark hair in 23 cases (31.9%). YDs per field of vision was considered as the most common finding with increased severity of AA.

Conclusion

YDS, in increased number per field of vision, is the most consistent finding seen in severe cases of AA, as they are in progressive AA and alopecia universalis. An increased number of SVH and terminal hairs were seen in patients who were being treated.

Peptic Ulcer Disease in Bangladesh: A Multi-centre Study

The incidence of peptic ulcer has steadily declined through out the world. This decreasing trend is also noticeable in this subcontinent. The point prevalence of peptic ulcer (PUD) in Bangladesh was around 15% in eighties. The aim of this study was to see the present prevalence of peptic ulcer at endoscopy and to identify changing trends in the occurrence of peptic ulcer in Bangladesh. This retrospective analysis of the endoscopic records of multiple tertiary referral centres of Dhaka city were done from January 2012 to July 2013. A total of 5608 subjects were the study samples. We included those patients having peptic ulcer in the form of duodenal ulcer, benign gastric ulcer including pre-pyloric ulcer and gastric outlet obstruction due to peptic ulcer. Duodenal ulcer and benign gastric ulcer were found in 415(7.4%) and 184(3.28%) patients respectively and gastric outlet obstruction due to peptic ulcer was found in 23(0.40%) patients.

Pattern of Changes in the Findings among the Patients Undergoing Diagnostic Esophagogastroduodenoscopy in Bangladesh

This cross-sectional observational study was conducted in the Department of Gastroenterology, Bangabandhu Sheikh Mujib Medical University, Sir Salimullah Medical College and Mitford Hospital, Holy family Red Crescent Medical College and Hospital and Popular Diagnostic Centre, Shantinagar branch, Dhaka, Bangladesh from January 2012 to July 2013. Study subjects were included in the study irrespective of age and sex having different upper GI tract. Complaints like dysphagia, heart burn, abdominal pain/dyspepsia, nausea, vomiting, haematemesis and/or malena, anorexia, unexplained anemia, weight loss etc. All the findings of oesophagus, stomach and duodenal lesions were observed and data were recorded. The results were considered positive based on the macroscopic appearance using standard diagnostic criteria. During the study period endoscopy was performed in 5608 subjects. Among which 2968(52.92%) were male and 2640(47.07%) were female. The patients age range from 7 years to 108 years. The majority of the patients were from 40-50 years. Normal findings were observed among 3321(59.21%) cases. Gastroduodenal erosions were present among 684(12.19%) cases, Oesophageal varices in 444(7.91%) cases, duodenal ulcer diseases in 415(7.40%) cases and gastric ulcer in 184(3.28%) cases. Ca stomach was found among 165(2.94%) cases. A number of diseases were identified through this procedure. Current study observed a large proportion of patients (40.79%) had positive upper GI endoscopy.

Structural analysis and molecular docking of potential ligands with chorismate synthase of Listeria monocytogenes: a novel antibacterial drug target

Listeriosis, in particular that caused by Listeria monocytogenes, is a major foodborne pathogen, and its control is becoming difficult because of widespread emergence of drug resistance strains. Chorismate synthase (CS), an essential enzyme of shikimate pathway present only in bacteria, fungi, plant and some apicomplexan parasites, is a validated potential antimicrobial drug target. Antimicrobial development through the elucidation of essential structural features of the CS of L. monocytogenes (LmCS), identification and prioritization of potential lead compounds targeted against LmCS were done. Structure-based virtual screening and docking studies were performed using Autodock tools to retrieve potential candidates with high affinity binding against LmCS model from several ligand repositories. The potency of binding was also checked with other structurally similar CS from Streptococcus pneumoniae (SpCS) and Mycobacterium tuberculosis (MtCS). The sequence and structural studies revealed LmCS was similar to be other CS structures (1Q1L, 1QXO, 1R52, 1R53, 1SQ1, 1UMO, 1UMF, 1ZTB, 2011, 2012, 4ECD and 2G85) with each monomer presenting β-α-β sandwich topology with a central helical core. Molecular docking studies and ADME/Tox results revealed that ZINC03803450 and ZINC20149031 were most potent molecules binding into the active site of LmCS. Other two ligands ZINC13387711-and ZINC16052528 showed a strong binding affinity score against all three structures (LmCS, SpCS and MtCS) and bind to LmCS with the predicted inhibition constant (K(i)) values of 22.94 nM and 35.84 nM, respectively. A reported benzofuran-3[2H]-one analog CHEMBL135212 with good ADME/Tox properties and experimental IC50 (nM) value of 7000 nM with SpCS could also be considered as a potential inhibitor of LmCS, as compared to previously reported 41 benzofuran-3[2H]-one analogs against SpCS. This information will assist in discovering those compounds that may act as potent CS inhibitors. Further experimental studies and evaluation of structure-activity relationship could help in the development of potential inhibitors against listeriosis, as well as antibacterial chemotherapy.

Non-enzymatic glucose sensing by enhanced Raman spectroscopy on flexible ‘as-grown’ CVD graphene

Unmodified, as-grown few layer graphene (on copper) have been used for glucose sensing using Raman spectroscopy. The origin of the graphene enhanced Raman spectroscopy (GERS) signal of glucose is attributed to a charge transfer from glucose to graphene.

Genotypes of hepatitis C virus infection in Bangladeshi population

Hepatitis C virus (HCV) is a leading cause of chronic liver disease worldwide also in Bangladesh. Prevalence of Hepatitis C virus infection in rural adult population of Bangladesh is reported to be 0.6% but the exact pattern of existing genotype has not been well studied. Genotyping of HCV is important for the planning of treatment duration and predicting the response to treatment in HCV infection. This study was done to identify the existing HCV genotypes in the diagnosed cases of chronic hepatitis C infection in Bangladesh. This study was a prospective as well as retrospective cross-sectional observational study done in the department of Gastroenterology of Bangabandhu Sheikh Mujib Medical University, Dhaka Bangladesh. Cases were also taken from department of Hepatology of Bangabandhu Sheikh Mujib Medical University and Square General Hospital, Dhaka. The study was from January 2010 to March 2011. In total, 417 patients having chronic HCV confirmed by positive anti-HCV and HCV-RNA tests attending to above mentioned institutions were included in this study. Out of the 417 study subjects, 303 were males (72.66%) and 114 (27.34%) were females between 05 to 78 years of age. Most cases were in the age group 30-50 years (57.06%). The study showed that 209 (50.19%) were infected with Genotype 3. Next common identified genotype of HCV was a combination of type 3 & 4, which accounted for 120 (28.77%) and genotype -1 represented 59 (14.14%) of the cases. Other less common identified genotypes were 2, 4, 5 and mixed genotypes -1 & 3, 5 & 6 and 2 & 3; the figure being 12(2.87%), 8(1.91%), 1(0.23%), 5(1.19%), 2(0.47%) and 1(0.23%) respectively. Several subtypes were also found. Genotype 3 was the commonest HCV genotype among the Bangladeshi population. Different HCV genotypes will give a good idea regarding the plan of treatment and possible response rate as well as prognosis of HCV infection in Bangladesh. This study had some limitation like relatively smaller sample size and shorter period for the study. Further studies over a larger population are needed to draw any conclusive opinion.

Highly efficient visible light photocatalytic reduction of CO2 to hydrocarbon fuels by Cu-nanoparticle decorated graphene oxide

The production of renewable solar fuel through CO2 photoreduction, namely artificial photosynthesis, has gained tremendous attention in recent times due to the limited availability of fossil-fuel resources and global climate change caused by rising anthropogenic CO2 in the atmosphere. In this study, graphene oxide (GO) decorated with copper nanoparticles (Cu-NPs), hereafter referred to as Cu/GO, has been used to enhance photocatalytic CO2 reduction under visible-light. A rapid one-pot microwave process was used to prepare the Cu/GO hybrids with various Cu contents. The attributes of metallic copper nanoparticles (∼4-5 nm in size) in the GO hybrid are shown to significantly enhance the photocatalytic activity of GO, primarily through the suppression of electron-hole pair recombination, further reduction of GO's bandgap, and modification of its work function. X-ray photoemission spectroscopy studies indicate a charge transfer from GO to Cu. A strong interaction is observed between the metal content of the Cu/GO hybrids and the rates of formation and selectivity of the products. A factor of greater than 60 times enhancement in CO2 to fuel catalytic efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared with that using pristine GO.

Efficacy of adefovir dipivoxil therapy in patients with chronic hepatitis B viral infection

Hepatitis B virus (HBV) infection is a major public health problem in the world. About 30% of world population has serological evidence of HBV infection. The prevalence of chronic hepatitis B in Bangladesh is reported to be 7.8%. Several potentially effective agents with different mechanisms of action have entered clinical practice and adefovir dipivoxil is one of them. Studies on the efficacy of adefovir dipivoxil in Bangladeshi patients are lacking. This was a prospective study to find out the effect of one year adefovir therapy in patients with chronic hepatitis B virus infection who were HBeAg positive. Total number of patients included in this study was 68. Among them 53(77.94%) patients continued the therapy and completed follow up. At the end of one year of therapy, intention to treat analysis showed that the rate of response (HBeAg seroconversion and HBV DNA negative) was 37.73% which was comparable to the results obtained in other studies. There was major difference in the pre treatment serum ALT level between the responders and non-responders. Comparison of reduction of serum ALT level before treatment and after treatment showed that ALT level to be lower in both responder group and non responder group. Adefovir was effective in replicative HBV infection in Bangladeshi population. So we suggest that treatment can be started and subsequent follow up can be done in chronic HBV patients who are HBeAg positive without liver biopsy.

Prevalence of colorectal diseases in immunological fecal occult blood test (I-FOBT) positive patients in a tertiary care hospital in Bangladesh

Bleeding lesion anywhere in the GI tract can cause positive reaction to Immunological Fecal Occult Blood Test (FOBT). Although any colonic lesion can cause occult lower GI bleeding, relative frequency of this lesion not known. Guaic based tests require prior preparation and dietary restriction and less sensitive and specific than IFOBT for detection of occult bleeding .IFOBT is specific for human hemoglobin and is more sensitive and specific for detection of occult bleeding from any colonic lesion. Aim of this study was to diagnose occult gastrointestinal bleeding with positive IFOBT and the prevalence of colorectal disease in IFOBT positive patients in a tertiary care hospital in Bangladesh. This was a prospective cross sectional study conducted in Department of gastroenterology in collaboration with clinical pathology, BSMMU, Dhaka during the period of January 2009 to December 2009. In this study 200 patients meeting the inclusion criteria were included. Detailed clinical history and physical findings were recorded; FOBT was done on single stool specimen. Positive occult bleeding was confirmed in 90 patients of whom 80 patients underwent colonoscopy. The mean age of study population was 36.73±13.64 (range 16 to 72) years. At colonoscopy lesion were identified in 46(57.50%) patients, of which colonic polyp in12 (15%), colorectal cancer in 11(13.7%), inflammatory bowel disease in 3(3.75%), hemorrhoids and anal fissure in 7(8.75%), tuberculosis in 5(6.25%), and proctitis in 1(1.25%) cases. A positive IFOBT is more sensitive and specific test than other FOBT for detection of occult lower GI bleeding of colonic origin. In this study colorectal diseases were detected in 57.50% of the IFOBT positive patients, so IOBT can be used as an important diagnostic tool for detection of occult lower GI bleeding.

Disease extent and local complication of ulcerative colitis in Bangladeshi population

Ulcerative colitis may involve anywhere from the rectum alone to the entire colon. Local complications like perforation, life threatening haemorrhage, toxic megacolon, pseudo polyps, stricture, and carcinoma of colon are seen. Patients who were diagnosed as Ulcerative Colitis in Departmental Ulcerative Colitis record book from January 1990 to June 2010 was considered as study population. Information regarding the extent of the disease and local complications were taken from earliest documented Lower GIT Endoscopy. Out of 164 patients disease extent were seen in 126(76.83%) patients and among them proctitis/proctosigmoiditis were seen in 57(45.24%) patients, left sided colitis were seen in 11(8.73%) patients, extensive/pan colitis were seen in 58(46.03%) patients. Complication were seen in 164 patients and 1(0.60%) patient had life threatening haemorrhage, 25(15.24%) patients developed pseudo polyps. There was no report of perforation, toxic megacolon, stricture or carcinoma of colon. The differences found between our study and studies from other Western and Asian countries in terms of complication rate and disease extent for were probably due to low index of suspicion, incomplete workup, or incomplete records, and influence of various environmental factors. So, further large scale prospective evaluation is suggested.

Detection of melamine on fractals of unmodified gold nanoparticles by surface-enhanced Raman scattering

A simple way of detecting melamine in raw milk is demonstrated via surface-enhanced Raman spectroscopy (SERS) using fractals of bare and nonfunctionalized ~30 nm gold nanoparticles (AuNP) distributed on a solid support. The technique demonstrates the formation of AuNP fractals, from a random distribution, upon exposure to melamine, that enhance the Raman scattering cross-section to enable detection by SERS. The agglomeration, which is pronounced at higher melamine concentrations, is demonstrated directly through imaging, and the red-shift of the plasmon absorption peak of the AuNP fractal away from 530 nm by finite difference time domain (FDTD) calculations. The agglomeration results in a strong plasmon field, shown by FDTD, over the interparticle sites that enhances the Raman scattering cross-section of melamine and ensures unambiguous detection. Limit of detection of 100 ppb could be achieved reproducibly.

An ink-jet printed, surface enhanced Raman scattering paper for food screening

A surface enhanced Raman spectroscopy active strip, with gold nanoparticles, is developed on paper by ink-jet printing for toxic screening.

Efficacy of Peppermint oil in diarrhea predominant IBS - a double blind randomized placebo - controlled study

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorder which is associated with considerable sufferings of patient and Peppermint oil is volatile oil, its active principle is menthol-contain a cyclic monoterpine which has anti-spasmotic properties due to its ability to block calcium channel of intestinal smooth muscles. This study observed the efficacy of peppermint oil for relieving the symptoms and changes of quality of life (QOL) in diarrhea predominant IBS. This was a prospective double blind randomized placebo-controlled study conducted in the Bangabandhu Sheikh Mujib Medical University during July 2008 to September 2009. Patients who fulfilled ROME II were initially selected but those had red flag signs or any organic disease was excluded from the study. Seventy four patients were enrolled in the study and randomly allocated to receive either peppermint oil or placebo three times daily for six weeks. Changes of symptoms were assessed three week interval during treatment and two weeks after the end of treatment. Data were analyzed by paired and unpaired 't' test. Finally sixty five patients completed the trial. It was observed that, at six weeks of therapy abdominal pain is markedly improved (mean±SD) 4.94±1.30 in peppermint oil group compared with 6.15±1.24 in placebo group and the difference was statistically highly significant (p>0.001). But two weeks after end of trials pain score again increased (6.09±1.93). Other symptoms and quality of life did not improve significantly. So the study result concludes that peppermint oil is effective in reliving only abdominal pain in diarrhea predominant IBS transiently.

Clinicopathological profile of patients with abdominal tuberculosis

BACKGROUND

Tuberculosis (TB) is not a uncommon problem throughout the world particularly in the developing countries like Nepal, India and Bangladesh. Abdominal Tuberculosis accounts for nearly 2% of tuberculosis worldwide. The aim of this study was to evaluate the clinicopathological profile with the help of other investigations in the diagnosis of patients with abdominal TB and their response to anti-tubercular therapy. This was a prospective cross-sectional study conducted in the department of Gastroenterology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka during the period of October 2002 to June 2009.

METHODS

Total 53 patients with abdominal TB diagnosed on the basis of clinical profile and supported investigation data like gross morphological findings at endoscopy, colonoscopy, diagnostic laparoscopy , laparotomy or histologically proven caseating granulomas were selected for this study. Detailed demographic, clinical profile, investigations and treatment response were recorded properly in a predesigned data collection sheet which were analyzed and compared with other studies.

RESULTS

Out of the 53 patients, 33 were males and 20 females with age ranging 16-70 (Mean 30.01±11.7) years. Abdominal pain was the most common presenting symptom in 47 (88.68%), fever in 45 (84.9%) and weight loss in 37 (69.81%) cases. Anemia was found in 41 (77.36%), cachexia 40 (75.47%), ascites 20 (37.74%), palpable abdominal mass in 14 (26.42%) and features of intestinal obstruction in 5 (9.43%) cases. Five patients had positive family history of TB and five had past history of pulmonary TB. The diagnosis of abdominal TB was confirmed microscopically in 5 (9.43%), histopathologically in 31 (58.49%) and the remaining 17 (32.07%) cases were diagnosed by a positive response to anti-TB therapy. According to site of involvement, 31 (58.51%), patients had intestinal TB, 9 (16.98%) had peritoneal TB and disseminated TB in 20 (37.74%) of the case. Twenty seven patients were given 3 drugs regimen for 12 months and 26 patients received 4 drugs regimen for 9 months under close supervision. By 9 months of therapy 51 patients become symptom free and no pathological findings were observed thereafter at follow up visits after 6 months. Response was not satisfactory in two patients and subsequent follow up investigation revealed to have crohn's disease rather than TB and none of them died.

CONCLUSIONS

Abdominal TB is an important clinical entity having varied mode of clinical presentation. So the diagnosis of abdominal TB is difficult and careful approach to the patients and supportive investigation data are necessary to make the final diagnosis. Neither clinical features, laboratory, radiological and Endoscopic methods nor bacteriological and histopathological findings by themselves provide a gold standard in the diagnosis of abdominal TB. In this series of abdominal TB, intestinal TB was the most frequent clinical type and the common presenting symptoms were abdominal pain, fever and weight loss. If diagnosed early, it can be treated successfully with anti-TB drugs.

Cochlear Implant : Anaesthesia Challenges

BACKGROUND

Cochlear implants are now an acceptable therapeutic option for those patients with irreversible hearing loss and deaf-mutism. The surgery is time consuming and complicated. Hence, the technique of anaesthesia plays a crucial role in success of cochlear implant surgery. Cochlear implant patients have various types of syndromes which are important from anaesthetic as well as surgical point of view. Pre-implant preparation requires objective assessment of hearing, plain X-rays of skull and a CT scan of the temporal bone. Anaesthesia is required for objective assessment of hearing in children under five years of age, to obtain X-rays of skull, magnetic resonance imaging (MRI), CT scan, brain evoked response audiometry (BERA) testing and finally for cochlear implant surgery. Anaesthetic considerations include preoperative familiarisation with the patient and his family. Syndromal illnesses have specific anaesthetic significance such as presence of difficult airway or prolonged QT interval. Parental presence is highly desirable during induction of anaesthesia. Electro-surgical instruments especially monopolar ones, should not be used once the cochlear implant is in place.

METHODS

In our institution, all cases (15 children) received their cochlear implants under general anaesthesia and formed the study group. Children were administered midazolam orally and inj ketamine during CT scan. Our techniques of general anaesthesia were modified to permit use of nerve stimulators during surgery. To minimise the incidence of vertigo particularly after cochleostomy, postoperative nausea and vomiting, all patients received glycopyrrolate and fentanyl citrate intravenously prior to induction. Other agents used were, thiopentone, suxamethonium and end-tidal 1.3 MAC halothane in 1:2 mixture of oxygen and nitrous oxide (O2 and N2O). Electro diathermy was switched off, before the cochlear device was implanted on the patient. Patients were allowed to breathe spontaneously whenever nerve stimulator was used to locate the facial nerve. Inj Ondansetron 0.1 mg/kg was used as anti-emetic agent. Postoperative pain relief was initially provided with fentanyl 1 μg/kg IV and later with syrup ibuprofen.

RESULTS

There were no remarkable anaesthetic or surgical complication in our series except perilymph leakage in two cases.

Engineering generalized synchronization in chaotic oscillators

We report a method of engineering generalized synchronization (GS) in chaotic oscillators using an open-plus-closed-loop coupling strategy. The coupling is defined in terms of a transformation matrix that maps a chaotic driver onto a response oscillator where the elements of the matrix can be arbitrarily chosen, and thereby allows a precise control of the GS state. We elaborate the scheme with several examples of transformation matrices. The elements of the transformation matrix are chosen as constants, time varying function, state variables of the driver, and state variables of another chaotic oscillator. Numerical results of GS in mismatched Rössler oscillators as well as nonidentical oscillators such as Rössler and Chen oscillators are presented.

Li+ ion emission from a hot-plate alumina-silicate source stimulated by flash heating with an infrared laser

The Neutralized Drift Compression Experiment-II accelerator under construction at Lawrence Berkeley National Laboratory has been designed to employ a lithium-doped alumino-silicate (Al-Si) hot-plate surface-ionization ion source. In order to achieve the design 1 mA∕cm(2) current density, the emitter must be constantly kept at a high temperature, leading to the accelerated loss of Li material as ions or neutrals. As a result, the estimated lifetime of the source is 50 h. This lifetime can be extended if the source is kept at low temperature during standby, and pulse heated to the high temperature during the ion extraction phase only. A pulsed heating technique based on an infrared laser (CO(2) gas discharge, λ = 10.6 μm) is described in this paper. The feasibility of ion current emission stimulated by flash heating with an infrared (IR) laser was demonstrated. High repeatability of the laser-stimulated ion current was observed, creating an opportunity for modulation and gating of the ion current with a laser pulse. It was found that with the available low power (≈115 W∕cm(2)) IR laser, current densities as high as 0.8 mA∕cm(2) could be achieved with a 2.8 mm diameter source. Various approaches for scaling to a larger (10 cm diameter) source and the application of short pulse, high power lasers are discussed. The results and conclusions of this paper may apply to various species of hot-plate ion sources.