Optimizing Work Extraction in the Presence of an Entropic Potential: An Entropic Stochastic Resonance

We study the nontrivial thermodynamic responses of an overdamped Brownian system driven by an unbiased driving force when the particle is confined inside a bilobal irregular structure. The spatial irregularity of the confinement results in an effective entropic bistable potential along the direction of transport. We calculate the thermodynamic response functions in terms of the averaged work done and the absorbed heat over a cycle of driving. We find that the thermodynamic responses are influenced by the nonlinearity of the effective entropic potential, the frequency of the external periodic driving force, and the random thermal fluctuations in a nontrivial way. In the presence of an optimal amount of thermal noise and a favoring driving frequency, the process exhibits a resonance-like precedent in terms of both output work and absorbed heat. We explore the conditions to get best synchronized work extraction (or absorbed heat), which can be utilized as a potential quantifier of an entropic stochastic resonance phenomenon. Finally, we identify a hallmark of entropy dominance over an analogous energy-driven scenario in terms of output work.

A thermo-mechanically loaded rotating FGM cylindrical pressure vessels under parabolic changing properties: An analytical and numerical analysis

This study aims to develop an exact analytical solution for steady-state thermo-mechanical stress in a functionally graded (FG) thick-walled cylindrical vessel. The cylinder is subjected to combined rotational speed and internal pressures while the thermal load is with convective and radiative boundary conditions. The dimensionless governing equations and boundary conditions, represented as a quartic equation, are derived and solved using Ferrari's method. The temperature, displacement, and stress fields across the thick-walled cylindrical vessel are calculated by finding the roots of the quartic equation. In order to investigate the accuracy of the exact analytical solution, a numerical model is constructed based on a standard Galerkin discretization approach of the finite element method (FEM). The analytical solutions and the results obtained through FEM show a high level of agreement. Furthermore, the study analyzes the effects of material parameters on temperature, displacement, and stress fields. Displacement, temperature, and stress fields are presented in the form of dimensionless graphs along the radial direction. For the considered parametric studies, results revealed that parabolic grading is beneficial than conventional grading. This study reveals that for the thermal loading, the maximum temperature, displacement, and tangential stress decrease for the parabolic grading. A similar but lower value of temperature, displacement, and tangential stress is also observed in the case of thermomechanical loading. This study is expected to assist in the assessment of the reliability of load calculations and contribute to the overall durability of pressure vessels. The results obtained from this study can provide valuable insights into thermo-elasticity and the thermo-mechanical behavior of thick-walled cylindrical vessels and can aid in the design and optimization of such systems.

3D flower-like zirconium magnesium oxide nanocomposite for efficient fluoride removal

A 3D flower-shaped bimetallic nanocomposite zirconium magnesium oxide (ZMO) was prepared first time by the controlled solution combustion method using triethanolamine (TEA) as a fuel and chelating agent. The composite material was used to remove excess fluoride via adsorption. The thermal stability of the adsorbent was characterized by thermogravimetric analysis (TGA). Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD) were used to characterize the adsorbent. The surface charge of the nano adsorbent was determined by Zeta Sizer. The surface area and pore volume of the adsorbent were determined by Brunauer-Emmett-Teller (BET) isotherm and Barrett-Joyner-Halenda (BJH) methods. The adsorption behavior of fluoride was studied systematically varying the pH, contact time, adsorbent dose, and initial fluoride concentration. The adsorption followed the Langmuir isotherm model with a maximum adsorption capacity of 42.14 mg/g. The pseudo-second-order kinetic model was confirmed by the adsorption study. The maximum adsorption efficiency was in the 6-10 pH range. The reaction mechanism was mainly based on ion exchange between hydroxy and fluoride ions which was proven by X-ray photoelectron spectroscopy (XPS). Real water tests indicated that ZMO could be used as a potential defluoridation agent for fluoride containing groundwater treatment.

Modulation-doping a correlated electron insulator

Correlated electron materials (CEMs) host a rich variety of condensed matter phases. Vanadium dioxide (VO2) is a prototypical CEM with a temperature-dependent metal-to-insulator (MIT) transition with a concomitant crystal symmetry change. External control of MIT in VO2-especially without inducing structural changes-has been a long-standing challenge. In this work, we design and synthesize modulation-doped VO2-based thin film heterostructures that closely emulate a textbook example of filling control in a correlated electron insulator. Using a combination of charge transport, hard X-ray photoelectron spectroscopy, and structural characterization, we show that the insulating state can be doped to achieve carrier densities greater than 5 × 1021 cm-3 without inducing any measurable structural changes. We find that the MIT temperature (TMIT) continuously decreases with increasing carrier concentration. Remarkably, the insulating state is robust even at doping concentrations as high as ~0.2 e-/vanadium. Finally, our work reveals modulation-doping as a viable method for electronic control of phase transitions in correlated electron oxides with the potential for use in future devices based on electric-field controlled phase transitions.

Rate enhancement of gated drift-diffusion process by optimal resetting

"Gating" is a widely observed phenomenon in biochemistry that describes the transition between the activated (or open) and deactivated (or closed) states of an ion-channel, which makes transport through that channel highly selective. In general, gating is a mechanism that imposes an additional restriction on a transport, as the process ends only when the "gate" is open and continues otherwise. When diffusion occurs in the presence of a constant bias to a gated target, i.e., to a target that switches between an open and a closed state, the dynamics essentially slow down compared to ungated drift-diffusion, resulting in an increase in the mean completion time, ⟨TG⟩ > ⟨T⟩, where T denotes the random time of transport and G indicates gating. In this work, we utilize stochastic resetting as an external protocol to counterbalance the delay due to gating. We consider a particle in the positive semi-infinite space that undergoes drift-diffusion in the presence of a stochastically gated target at the origin and is moreover subjected to rate-limiting resetting dynamics. Calculating the minimal mean completion time ⟨Tr⋆G⟩ rendered by an optimal resetting rate r⋆ for this exactly solvable system, we construct a phase diagram that owns three distinct phases: (i) where resetting can make gated drift-diffusion faster even compared to the original ungated process, ⟨Tr⋆G⟩<⟨T⟩<⟨TG⟩, (ii) where resetting still expedites gated drift-diffusion but not beyond the original ungated process, ⟨T⟩≤⟨Tr⋆G⟩<⟨TG⟩, and (iii) where resetting fails to expedite gated drift-diffusion, ⟨T⟩<⟨TG⟩≤⟨Tr⋆G⟩. We also highlight various non-trivial behaviors of the completion time as the resetting rate, gating parameters, and geometry of the set-up are carefully ramified. Gated drift-diffusion aptly models various stochastic processes such as chemical reactions that exclusively take place in certain activated states of the reactants. Our work predicts the conditions under which stochastic resetting can act as a useful strategy to enhance the rate of such processes without compromising their selectivity.

Harnessing the hydrogen evolution reaction (HER) through the electrical mobility of an embossed Ag(I)-molecular cage and a Cu(II)-coordination polymer

A structurally characterized porous Ag(I)-molecular cage Ag_MOC and a Cu(II)-coordination polymer Cu_CP with a pre-synthesized ligand 1,3-bis(((E)-2-methoxybenzylidene)amino)propan-2-ol and its parental amine with thiocyanate are reported to harness electrical mobility-driven hydrogen evolution activity. Porosity-induced electrically conductive Ag_MOC emerges as a better electrocatalyst with a Tafel slope of 104 mV per decade over Cu(II)-polymer's slope of 128 mV per decade. The electrochemical stability and durability of the designed electrocatalysts in harnessing the HER activity are also examined under experimental conditions.

Geometric Brownian information engine: Essentials for the best performance

We investigate a geometric Brownian information engine (GBIE) in the presence of an error-free feedback controller that transforms the information gathered on the state of Brownian particles entrapped in monolobal geometric confinement into extractable work. Outcomes of the information engine depend on the reference measurement distance x_{m}, the feedback site x_{f}, and the transverse force G. We determine the benchmarks for utilizing the available information in an output work and the optimum operating requisites for best achievable work. Transverse bias force (G) tunes the entropic contribution in the effective potential and hence the standard deviation (σ) of the equilibrium marginal probability distribution. We recognize that the amount of extractable work reaches a global maximum when x_{f}=2x_{m} with x_{m}∼0.6σ, irrespective of the extent of the entropic limitation. Because of the higher loss of information during the relaxation process, the best achievable work of a GBIE is lower in an entropic system. The feedback regulation also bears the unidirectional passage of particles. The average displacement increases with growing entropic control and is maximum when x_{m}∼0.81σ. Finally, we explore the efficacy of the information engine, a quantity that regulates the efficiency in utilizing the information acquired. With x_{f}=2x_{m}, the maximum efficacy reduces with increasing entropic control and shows a crossover from 2 to 11/9. We discover that the condition for the best efficacy depends only on the confinement lengthscale along the feedback direction. The broader marginal probability distribution accredits the increased average displacement in a cycle and the lower efficacy in an entropy-dominated system.

One-pot solution combustion synthesis of porous spherical-shaped magnesium zinc binary oxide for efficient fluoride removal and photocatalytic degradation of methylene blue and Congo red dye

A novel porous spherical-shaped magnesium zinc binary oxide (MZO) was successfully prepared for the first time using a chemical process for fluoride removal and photocatalytic methylene blue (MB) and Congo red (CR) dye degradation. XRD, FESEM, and TEM were studied for phase formation, topographic, crystallographic, and detailed structural information. The surface charge and optical properties of the adsorbent were studied by zeta potential and photoluminescence spectra. The synthesized nano-adsorbents showed high fluoride removal capacity (43.10 mg/g) and photocatalytic activity with a degradation efficiency of 97.83% and 78.40% for MB and CR, respectively. The adsorption was strongly pH-dependent and worked well in the range 6-9. The kinetic studies were performed for both fluoride removal and dye degradation and were found to follow pseudo-second-order and first-order rate law, respectively. The samples were found to be extremely reusable and selective for fluoride removal in presence of co-ions such as NO₃^-, SO₄^2-, and Cl^-. The basic fluoride adsorption process of the samples can be related to ion exchange and electrostatic interactions, according to XPS and FTIR data. The detailed mechanistic study of photocatalytic dye degradation showed that the reaction occurred via OH radicals. Thus, MZO could be considered an effective and quick adsorbent for water purification in fluoride-containing groundwater and industrial dye wastewater.

Etiology of Chronic Abnormal Uterine Bleeding According to the FIGO's PALM-COEIN Classification in Bangladeshi Women of Reproductive Age: A Cross-Sectional Study

Chronic abnormal uterine bleeding (AUB) is common, but there is a lack of standardized methods for investigating and etiological categorization of AUB. The PALM-COEIN classification system of AUB is getting important to overcome this issue. This cross-sectional study was conducted from January 2019 to December 2019 at Mymensingh Medical College Hospital, Mymensingh, Bangladesh, to determine the causes of AUB in women of the reproductive age group and categorize the causes of AUB as per the PALM-COEIN classification. A total of 380 women with chronic AUB were evaluated. The distribution of PALM-COEIN causes of AUB were AUB-P (1.8%), AUB-A (9.2%), AUB-L (13.2%), AUB-M (5.8%), AUB-C (1.1%), AUB-O (24.7%), AUB-E (1.6%), AUB-I (6.6%), and AUB-N (36.1%). The participants' mean age was 29.6 (±10.5) years, the majority (78.2%) of them was married, only a few (9.5%) had comorbid diseases, including hypertension (HTN) (1.1%), diabetes mellitus (DM) (5.3%), and hypothyroidism (8.7%). Women in the AUB-M classification had higher age than others; anemia was more prevalent in the AUB-P group, the AUB-O group had the highest TSH levels and hypothyroidism frequency. The PALM-COEIN classification helps ascertain the cause of AUB practically and should be used in routine clinical practices to manage these patients better.

Efficacy of Nebulized Hypertonic Saline (3%) Versus Normal Saline and Salbutamol in Treating Acute Bronchiolitis in A Tertiary Hospital: A Randomized Controlled Trial

Acute bronchiolitis is a viral respiratory illness of infants and young children that occurs in the first two years of life. It is a major cause of hospital admissions in Bangladesh. Management of bronchiolitis is a great challenge for the pediatrician both in the outpatient and inpatient department. Because mainstay of treatment options are usually supportive like cool humidified oxygen, fluids, bronchodilators, epinephrine and corticosteroids. A number of agents have been proposed as adjunctive therapies, but their effects are controversial. Nebulized hypertonic saline (3%) has been reported to have some benefit in recent studies. So the objective of this study was to compare the efficacy of nebulized 3% hypertonic saline (HS) with salbutamol and normal saline (0.9%) nebulization in children with acute bronchiolitis. A double-blind randomized controlled trial was conducted in the Department of Paediatrics, Mymensingh Medical College Hospital, Bangladesh from November 2015 to October 2016. A total of 100 children aged one month to two years with acute bronchiolitis admitted in the Pediatric wards of MMCH were included in the study and were randomly assigned to either 3% nebulized hypertonic saline (n=50) or to 0.9% nebulized isotonic saline with salbutamol solution (n=50). The main outcome variables were clinical severity score, length of hospital stay, duration of oxygen therapy and oxygen saturation (SpO2). The therapy was repeated three times on every hospitalization day and the outcome was evaluated two times daily (12 hourly) for 60 hours. Mean duration of oxygen therapy in study group was 33.6±21.7 hours and in control group was 36.8±22.5 hours. But their difference was not statistically significant (p>0.05). The mean clinical severity score and mean oxygen saturation of the entire study patients in both groups decreased and increased respectively during hospital stay. There was significant difference of mean clinical severity score and oxygen saturation between admission and follow up-5 in each group (p<0.001). But their difference between two groups was not statistically significant (p>0.05). Mean duration of hospital stay was 2.91±1.54 days in study group and 3.09±1.85 days in control group. But their difference between two groups was not statistically significant (p>0.05). So in acute bronchiolitis nebulized hypertonic saline (3%) is as effective as normal saline (0.9%) and salbutamol nebulization.

Post-Acute Covid Neurological Symptoms among Doctors and Nurses in A Tertiary Care Hospital: An Observational Study from Bangladesh

A good number of patients experience post-Covid complications. Doctors and nurses are the front liners who are at greater risk of having this disease. Neurological symptoms are frequent in patients with post-COVID-19 infection. The study aims to observe the post-acute neurological symptoms among doctors and nurses of Mymensingh Medical College Hospital, a tertiary care hospital in Bangladesh, after they recover from initial infection or among the asymptomatic cases. It was a retrospective observational study among the doctors and nurses who became RT PCR positive from late April to mid-September 2020. A total of 100 subjects were interviewed over the phone for the presence or absence of neurological symptoms four weeks post Covid-19 infection. Total 54 doctors and 46 nurses were evaluated; the male-female ratio was 1:1.77, the mean age was 35.6±7.6 years. Post-acute COVID neurological symptoms (PACNS) were present in 60% of respondents. Fatigue (51%) was the most common symptom, followed by sleep disturbance, headache, myalgia, loss of taste and smell. PACNS were more in symptomatic patients at the initial Covid infection than asymptomatic cases.

Geometric Brownian information engine: Upper bound of the achievable work under feedback control

We design a geometric Brownian information engine by considering overdamped Brownian particles inside a two-dimensional monolobal confinement with irregular width along the transport direction. Under such detention, particles experience an effective entropic potential which has a logarithmic form. We employ a feedback control protocol as an outcome of error-free position measurement. The protocol comprises three stages: measurement, feedback, and relaxation. We reposition the center of the confinement to the measurement distance (x_p) instantaneously when the position of the trapped particle crosses x_p for the first time. Then, the particle is allowed for thermal relaxation. We calculate the extractable work, total information, and unavailable information associated with the feedback control using this equilibrium probability distribution function. We find the exact analytical value of the upper bound of extractable work as (53-2ln2)k_BT. We introduce a constant force G downward to the transverse coordinate (y). A change in G alters the effective potential of the system and tunes the relative dominance of entropic and energetic contributions in it. The upper bound of the achievable work shows a crossover from (53-2ln2)k_BT to 12k_BT when the system changes from an entropy-dominated regime to an energy-dominated one. Compared to an energetic analog, the loss of information during the relaxation process is higher in the entropy-dominated region, which accredits the less value in achievable work. Theoretical predictions are in good agreement with the Langevin dynamics simulation studies.

Escape kinetics of self-propelled particles from a circular cavity

We numerically investigate the mean exit time of an inertial active Brownian particle from a circular cavity with single or multiple exit windows. Our simulation results witness distinct escape mechanisms depending on the relative amplitudes of the thermal length and self-propulsion length compared to the cavity and pore sizes. For exceedingly large self-propulsion lengths, overdamped active particles diffuse on the cavity surface, and rotational dynamics solely governs the exit process. On the other hand, the escape kinetics of a very weakly damped active particle is largely dictated by bouncing effects on the cavity walls irrespective of the amplitude of self-propulsion persistence lengths. We show that the exit rate can be maximized for an optimal self-propulsion persistence length, which depends on the damping strength, self-propulsion velocity, and cavity size. However, the optimal persistence length is insensitive to the opening windows' size, number, and arrangement. Numerical results have been interpreted analytically based on qualitative arguments. The present analysis aims at understanding the transport controlling mechanism of active matter in confined structures.

Noise-induced symmetry breaking of self-regulators: Nonequilibrium transition toward homochirality

We present a theoretical model to study the origin of chiral symmetry breaking of a racemic mixture of optically active biomolecules. We consider a collection of Brownian particles, which can stay in any of the three possible isomeric states: one achiral and two enantiomers. Isomers are undergoing self-regulatory reaction along with chiral inhibition and achiral decay processes. The reaction rates of the isomeric states are guided by their neighbors as well as the thermal fluctuations of the system. We find that an alteration in the relative dominance of self-regulation, chiral inhibition, and achiral decay processes breaks the chiral symmetry of the system, which is either partial or complete. This results in four different asymmetric population states, viz., three-isomer coexistence, enantiomeric coexistence, chiral-achiral coexistence, and homochiral state. A change in the reaction condition induces nonequilibrium transition among these states. We also report that a fast stochastic self-regulation and a slow chiral inhibition and achiral decay process along with a threshold population of interacting neighbors suffice for the requisite for transition toward a completely symmetry broken state, i.e., homochirality.

VLBI measurement of the vector baseline between geodetic antennas at Kokee Park Geophysical Observatory, Hawaii

We measured the components of the 31-m-long vector between the two very-long-baseline interferometry (VLBI) antennas at the Kokee Park Geophysical Observatory (KPGO), Hawaii, with approximately 1 mm precision using phase delay observables from dedicated VLBI observations in 2016 and 2018. The two KPGO antennas are the 20 m legacy VLBI antenna and the 12 m VLBI Global Observing System (VGOS) antenna. Independent estimates of the vector between the two antennas were obtained by the National Geodetic Survey (NGS) using standard optical surveys in 2015 and 2018. The uncertainties of the latter survey were 0.3 and 0.7 mm in the horizontal and vertical components of the baseline, respectively. We applied corrections to the measured positions for the varying thermal deformation of the antennas on the different days of the VLBI and survey measurements, which can amount to 1 mm, bringing all results to a common reference temperature. The difference between the VLBI and survey results are 0.2 ± 0.4 mm, -1.3 ± 0.4 mm, and 0.8 ± 0.8 mm in the East, North, and Up topocentric components, respectively. We also estimate that the Up component of the baseline may suffer from systematic errors due to gravitational deformation and uncalibrated instrumental delay variations at the 20 m antenna that may reach ± 10 and -2 mm, respectively, resulting in an accuracy uncertainty on the order of 10 mm for the relative heights of the antennas. Furthermore, possible tilting of the 12 m antenna increases the uncertainties in the differences in the horizontal components to 1.0 mm. These results bring into focus the importance of (1) correcting to a common reference temperature the measurements of the reference points of all geodetic instruments within a site, (2) obtaining measurements of the gravitational deformation of all antennas, and (3) monitoring local motions of the geodetic instruments. These results have significant implications for the accuracy of global reference frames that require accurate local ties between geodetic instruments, such as the International Terrestrial Reference Frame (ITRF).

407 Incidental Focal Intrahepatic Duct Dilatation (FIDD) – A Finding That Mandates Further Investigation That May Include Liver Resection

Background

The increasing use of imaging has led to incidental findings in the liver. The Western experience of managing focal intrahepatic duct dilatation (FIDD) is not well recorded. We present our experience based on a large prospectively maintained database at a tertiary hepatobiliary surgical unit.

Method

Patients with liver resection for FIDD between January 2003-December 2019 were retrospectively identified from the liver unit database. The demographics, symptomatology, blood test results, imaging, type of liver resection, morbidity, mortality, and histology of resected specimens were recorded.

Results

9 patients had FIDD among 994 liver resections performed (0.9%). 6 patients were asymptomatic, 2 upper abdominal pain and 1 recurrent gram-negative sepsis. Liver function tests were normal in all patients. Two patients had cholangiocarcinoma (CCA), 4 intrahepatic stones, 1 intraductal papillary neoplasm of bile duct (IPN –B) and 2 benign strictures.

Conclusions

FIDD is rare in the Western population. Most patients are asymptomatic with an incidental finding of FIDD on cross-sectional imaging. Differentiating benign and malignant pathology is difficult warranting liver resection in fit patients to resolve the diagnosis. Liver resection is safe and can be potentially curative in patients with a neoplasm, which can occur in 30% of patients with FIDD.

Diversity of Vibrio parahaemolyticus in marine fishes of Bangladesh

AIMS

To determine the occurrence, diversity, antibiotic resistance and biofilm formation of Vibrio parahaemolyticus isolated from marine fishes in Bangladesh.

METHODS AND RESULTS

A total of 80 marine fishes were obtained from the local markets and examined for the presence of V. parahaemolyticus. All the isolated V. parahaemolyticus were characterized for the presence of virulence markers, thermostable direct hemolysin (TDH) or thermostable direct hemolysin related hemolysin (TRH). Isolates were serotyped and further characterized by enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) typing to analyse the genetic diversity. Moreover, biofilm formation and antibiotic resistance patterns were also determined. About 63·75% (51/80) of the tested marine fishes were contaminated with V. parahaemolyticus. From the contaminated fishes, 71 representatives V. parahaemolyticus were isolated and none of them harboured tdh and trh virulence genes. Nine different O-groups and seven different K-types were found by serological analysis and the dominant serotype was O5:KUT. In ERIC-PCR analysis, eight clusters (A-H) were found and the most common pattern was A (46·5%). All of the isolates were resistant to ampicillin and 78·9% of isolates were resistant to streptomycin. The highest biofilm formation was found at 37°C compared to 25°C and 4°C.

CONCLUSION

Diverse V. parahaemolyticus are present in marine fishes in the local market of Bangladesh with antibiotic-resistant properties and biofilm formation capacity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The widespread prevalence of diverse V. parahaemolyticus in marine fishes is an issue of serious concern, and it entails careful monitoring to ascertain the safety of seafood consumers.

Exploring the structure of Xe isotopes in A ~ 130 region: Single particle and collective excitations

High and medium spin structures of 130,131Xe have been studied using α-induced fusion-evaporation reaction and the Indian National Gamma Array (INGA) coupled with a digital data acquisition system. Various new band structures and near yrast levels of 131Xe have been established. The multipolarities of the observed transitions have been assigned on the basis of the DCO ratios and the polarization asymmetry measurements. Band structures based on 1-quasi-particle (qp), 3-qp configurations have been observed. A new Magnetic Rotational (MR) band based on 5-qp configuration has also been established in 131Xe. The MR band has been interpreted in terms of shears mechanism with principal axis cranking (SPAC) calculations. Shell Model calculations are carried out to describe the non yrast states of 131Xe above the 11/2− isomer. New excited states have also been identified in 130Xe, produced in the same reaction.

Chromogenic and fluorogenic “off–on–off” chemosensor for selective and sensitive detection of aluminum (Al3+) and bifluoride (HF2−) ions in solution and in living Hep G2 cells: synthesis, experimental and theoretical studies

A simple pyridine-dicarbohydrazide based colorimetric and fluorometric chemosensor L was designed and synthesized for Al³⁺ ion sensing in organo aqueous solution.

Pseudochemotaxis in inhomogeneous active Brownian systems

We study dynamical properties of confined, self-propelled Brownian particles in an inhomogeneous activity profile. Using Brownian dynamics simulations, we calculate the probability to reach a fixed target and the mean first passage time to the target of an active particle. We show that both these quantities are strongly influenced by the inhomogeneous activity. When the activity is distributed such that high-activity zone is located between the target and the starting location, the target finding probability is increased and the passage time is decreased in comparison to a uniformly active system. Moreover, for a continuously distributed profile, the activity gradient results in a drift of active particle up the gradient bearing resemblance to chemotaxis. Integrating out the orientational degrees of freedom, we derive an approximate Fokker-Planck equation and show that the theoretical predictions are in very good agreement with the Brownian dynamics simulations.

Cytokines and chemokines measured in dried SLA-stimulated whole blood spots for asymptomatic Leishmania infantum and Leishmania donovani infection

Whole blood stimulation with soluble Leishmania antigen (SLA), followed by plasma cytokine and chemokine determination, provides means of detecting subjects with asymptomatic Leishmania infection. This work examines the potential of Protein Saver 903 cards for the storage and transport of SLA-stimulated dried plasma spot samples. Blood was collected from asymptomatic and negative control subjects living in a Leishmania infantum- (Spain) and Leishmania donovani-endemic area (Bangladesh). After SLA-stimulation, three types of sample were prepared: frozen liquid plasma (-20 °C), and plasma dropped onto Protein Saver cards kept at -20 °C (DPS-FZ), and at ambient temperature (DPS-AT). The concentrations of IFN-γ, IL-2, CXCL10, CXCL9, CCL2 and CXCL8 in the thawed liquid plasma (TLP), DPS-FZ and DPS-AT samples were then determined. Strong correlations were seen between the TLP and DPS-FZ/AT samples for all the studied cytokines/chemokines in both the L. infantum and L. donovani areas. Protein Saver 903 cards would therefore appear to allow for the transport of SLA-stimulated plasma samples by courier at ambient temperature. The CXCL10 and CXCL9 detectable in these plasma spots provided robust markers for identifying asymptomatic subjects from both endemic areas. This easy procedure opens up new possibilities for field studies in resource-limited settings, which could help in Leishmania control.

Outcome of Pregnancy Related Acute Kidney Injury Observed in a Tertiary Care Hospital

This prospective case control study was carried out in Mymensingh Medical College Hospital (MMCH) from April 2011 to March 2012. The main objective of the study was to determine the short term maternal outcome of pregnancy related Acute Kidney Injury and to identify aetiological factors and to observe clinical features of pregnancy related Acute Kidney Injury. Total 60 pregnant women with AKI were included in the study as sample and equal (60) number of pregnant women with normal renal function was taken as control. Mean ages (±SD) of study and control group were observed 31.6±6.9 years and 25.5±4.7 years respectively. It was observed that most patients were from rural area with low income group. Most women were multiparous and presented in third trimester and postpartum period. Majority of the study subjects did not receive antenatal care at any stage of pregnancy. Fifty (86.7%) of the study subjects were oligo-anuric, forty-nine (81.7%) were edematous and fifty one (85%) were anaemic. Twenty-five (41.7%) patients presented with abnormal vaginal bleeding. Sepsis (including septic abortion and puerperal sepsis) was responsible for of Pregnancy Related AKI (PR-AKI) in more than two fifths of cases. Haemorrhage (APH & PPH combined) was the next common cause of Pregnancy Related AKI (PR-AKI). Toxemia of Pregnancy was responsible in one fourth of cases. Dialysis (HD & IPD combined) was required for two fifths of the patients. Rest patients were treated conservatively with antibiotics, blood transfusion, maintenance of fluid and electrolytes balance etc. Maternal outcome of Pregnancy related acute kidney injury was considered for the period of patient's hospital staying. 56.6% patients recovered completely, 15.0% patients recovered partially, 6.7% did not recover at the time of hospital discharge; while 21.7% died. So it can be concluded that, pregnancy related acute kidney injury is a critical condition, associated with worse prognosis.

Current Trends of Using Antimicrobials at Obstetrics and Gynaecology Department in a Tertiary Care Hospital

This cross-sectional descriptive study was done to analyse the current trends of using antimicrobials in various surgical procedures at Obstetrics and Gynaecology department in Mymensingh Medical College Hospital, Mymensingh from July 2014 to June 2015. Among 300 postoperative obstetrics and gynaecological surgery cases, samples were selected as non-random purposive selection method where pattern of using antimicrobials were analysed by SPSS method 20.1 versions. The incidence of antimicrobial resistance is on continued rise with a threat to return to the pre-antibiotic era. This has led to emergence of such bacterial infections which are essentially untreatable by the current armamentarium of available treatment options. Now-a-days variation of choosing antibiotic are quietly accepted in Obstetrics and Gynaecology department as prophylaxis purpose to control life threatening conditions such as postoperative wound infection, septicaemia, urinary tract infection etc. The data analysis revealed that among 300 obstetrical and gynaecological surgeries, Nitroimidazoles (93.33%), Cephalosporins (91%) and Aminoglycosides (59%) group were most commonly used antimicrobials in both obstetrics and gynaecological surgeries. Metronidazole (93.33%), Ceftriaxone (68.66%), Gentamicin (60.33%), Cefuroxime (48%), Flucloxacillin (42%), Cefixime (27%) were the most commonly used antimicrobials at obstetrics and gynaecology department. Combination of Ceftriaxone, Metronidazole and Gentamicin (37.66%), Ceftriaxone and Metronidazole (25.33%), Cefuroxime, Metronidazole and Gentamicin (16%), Ciprofloxacin, Metronidazole and Gentamicin (5.33%) were most commonly used antimicrobials postoperatively. Total mean duration of antimicrobial therapy was 10.45 days. Antibiotics are useful in prevention of infection. But indiscriminately use of antibiotics without any guideline may lead to antimicrobial resistance. So, antimicrobial surveillance committee should be formed by hospital authority to know the local using pattern of antibiotics.

Experimental Determination of η/s for Finite Nuclear Matter

We present, for the first time, simultaneous determination of shear viscosity (η) and entropy density (s) and thus, η/s for equilibrated nuclear systems from A∼30 to A∼208 at different temperatures. At finite temperature, η is estimated by utilizing the γ decay of the isovector giant dipole resonance populated via fusion evaporation reaction, while s is evaluated from the nuclear level density parameter (a) and nuclear temperature (T), determined precisely by the simultaneous measurements of the evaporated neutron energy spectra and the compound nuclear angular momenta. The transport parameter η and the thermodynamic parameter s both increase with temperature, resulting in a mild decrease of η/s with temperature. The extracted η/s is also found to be independent of the neutron-proton asymmetry at a given temperature. Interestingly, the measured η/s values are comparable to that of the high-temperature quark-gluon plasma, pointing towards the fact that strong fluidity may be the universal feature of the strong interaction of many-body quantum systems.

Fluoride enrichment in an alluvial aquifer with its subsequent effect on human health in Birbhum district, West Bengal, India

This research work primarily deals with the geochemistry and genesis of fluoride (F^-) in an alluvial aquifer with an emphasis on prevalence of dental and skeletal fluorosis among the endemic population. Hydrogeochemical outcomes reveal that chemical weathering and ion-exchange phenomena are the two dominant processes that make study area groundwater into NaHCO₃ water type. Presence of intercalated zeolite rich sediments (F_Total 412-446 mg/kg) having higher ion-exchange capacity (120-125 meq/100 g) within the aquifer is the source and mobilizing factors of F^- in groundwater respectively. Laboratory experiment further justifies higher desorption potential of aquifer sediments at the groundwater pH of 6.5-7.5. Health survey reveals that out of 235 studied population 60% suffer from dental fluorosis while females >30 years of age became exposed early to osteoporosis disease.

Functionalization of the Polymeric Surface with Bioceramic Nanoparticles via a Novel, Nonthermal Dip Coating Method

The only nonthermal method of depositing a bioceramic-based coating on polymeric substrates is by incubation in liquid, e.g., simulated body fluid to form an apatite-like layer. The drawbacks of this method include the long processing time, the production of low scratch resistant coating, and an end product that does not resemble the intended bioceramic composition. Techniques, such as plasma spraying and magnetron sputtering, involving high processing temperature are unsuitable for polymers, e.g., PMMA. Here, we introduce a nonthermal coating method to immobilize hydroxyapatite (HAp) and TiO₂ nanoparticles on PMMA via a simple and fast dip coating method. Cavities that formed on the PMMA, induced by chloroform, appeared to trap the nanoparticles which accumulated to form layers of bioceramic coating only after 60 s. The resulting coating was hydrophilic and highly resistant to delamination. In the context of our research and to address the current clinical need, we demonstrate that the HAp-coated PMMA, which is intended to be used as a visual optic of a corneal prosthetic device, improves its bonding and biointegration with collagen, the main component of a corneal stroma. The HAp-coated PMMA resulted in better adhesion with the collagen than untreated PMMA in artificial tear fluid over 28 days. Human corneal stromal fibroblasts showed better attachment, viability, and proliferation rate on the HAp-coated PMMA than on untreated PMMA. This coating method is an innovative solution to immobilize various bioceramic nanoparticles on polymers and may be used in other biomedical implants.

Stochastic resonance during a polymer translocation process

We have studied the occurrence of stochastic resonance when a flexible polymer chain undergoes a single-file translocation through a nano-pore separating two spherical cavities, under a time-periodic external driving force. The translocation of the chain is controlled by a free energy barrier determined by chain length, pore length, pore-polymer interaction, and confinement inside the donor and receiver cavities. The external driving force is characterized by a frequency and amplitude. By combining the Fokker-Planck formalism for polymer translocation and a two-state model for stochastic resonance, we have derived analytical formulas for criteria for emergence of stochastic resonance during polymer translocation. We show that no stochastic resonance is possible if the free energy barrier for polymer translocation is purely entropic in nature. The polymer chain exhibits stochastic resonance only in the presence of an energy threshold in terms of polymer-pore interactions. Once stochastic resonance is feasible, the chain entropy controls the optimal synchronization conditions significantly.

Impact of post-operative radiation on coronary arteries in patients of early breast cancer: A pilot dosimetric study from a tertiary cancer care center from India

BACKGROUND

The significant impact of postoperative radiotherapy (PORT) on cardiac morbidity in patients of early breast cancer (EBC) undergoing breast-conserving surgery has been shown in different studies. The present study was conducted to assess the impact of surgery and the side of involvement on radiation dose to left anterior descending artery (LAD) and Left circumflex coronary artery (LCx).

MATERIALS AND METHODS

Totally, 58 patients of EBC were randomly chosen for this dosimetric study and planned with tangential field technique without intensity modulation (IM). Heart, LAD, and LCx (n = 55) were contoured. Dose volume histograms were analyzed to determine the Dmax (maximum dose) and Dmean (mean dose) of LAD and LCx. Student's t-test was used for comparative analysis of the means.

RESULTS

The mean Dmax of LAD for left (L) EBC was 3.17 Gray (Gy) while for right (R) EBC it was 0.86 Gy (P = 0.007; 95% C.I, 1.14-3.48). The mean Dmean of LAD for L-EBC and R-EBC were 1.97 Gy and 0.79 Gy, respectively (P = 0.029; 95% C.I, 0.77-1.60). The mean-Dmax of LCx for patients with L-EBC (2.9 Gy; range: 1.2-4.35 Gy) was statistically higher than that for R-EBC (1.3 Gy; range: 0.7-3.2 Gy) (P = 0.045). The mean-Dmean of LCx for L-EBC (2.1 Gy; range: 0.6-3.6 Gy) was also significantly higher than that of L-EBC (0.9 Gy; range: 0.7-2.1 Gy) (P = 0.03). There was no significant impact of the pattern of surgery on LAD dose, but significance was noted for LCx dose parameters (P = 0.04 and 0.08 for m-Dmax and m-Dmean of LCx).

CONCLUSION

This pilot dosimetric study confirms the assumption that patients with left-sided EBC are at higher risk of developing long-term cardiac morbidity when treated with PORT due to increased dose to LAD.

Ratchet rectification effect on the translocation of a flexible polyelectrolyte chain

We report a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte chain, translocating through an asymmetric narrow channel with periodically varying cross sections under the influence of a periodic external electric field. When reflection symmetry of the channel is broken, a rectification effect is observed with a favored direction for the chain translocation. For a given volume of the channel unit and polymer length, the rectification occurs below a threshold frequency of the external periodic driving force. We have also observed that the extent of the rectification varies non-monotonically with increasing molecular weight and the strength of geometric asymmetry of the channel. Observed non-monotonicity of the rectification performance has been interpreted in terms of a competition between two effects arising from the channel asymmetry and change in conformational entropy. An analytical model is presented with predictions consistent with the simulation results.

Association of vitamin D status with incidence of enterotoxigenic, enteropathogenic and enteroaggregative Escherichia coli diarrhoea in children of urban Bangladesh

OBJECTIVE

To evaluate the association between vitamin D status and diarrhoeal episodes by enterotoxigenic (ETEC), enteropathogenic (EPEC) and enteroaggregative (EAEC) E. coli in underweight and normal-weight children aged 6-24 months in urban Bangladesh.

METHODS

Cohorts of 446 normal-weight and 466 underweight children were tested separately for ETEC, EPEC and EAEC from diarrhoeal stool samples collected during 5 months of follow-up while considering vitamin D status at enrolment as the exposure. Cox proportional hazards models with unordered failure events of the same type were used to determine diarrhoeal risk factors after adjusting for sociodemographic and concurrent micronutrient status.

RESULTS

Vitamin D status was not independently associated with the risk of incidence of ETEC, EPEC and EAEC diarrhoea in underweight children, but moderate-to-severe retinol deficiency was associated with reduced risk for EPEC diarrhoea upon adjustment. Among normal-weight children, insufficient vitamin D status and moderate-to-severe retinol deficiency were independently associated with 44% and 38% reduced risk of incidence of EAEC diarrhoea, respectively. These children were at higher risk of ETEC diarrhoea with vitamin D deficiency status when adjusted for micronutrient status only.

CONCLUSION

This study demonstrates for the first time that normal-weight children with insufficient vitamin D status have a reduced risk of EAEC diarrhoea than children with sufficient status. Moderate-to-severe deficiency of serum retinol is associated with reduced risk of EPEC and EAEC diarrhoea in underweight and normal-weight children.

Study on the safety and efficacy of miltefosine for the treatment of children and adolescents with post-kala-azar dermal leishmaniasis in Bangladesh, and an association of serum vitamin E and exposure to arsenic with post-kala-azar dermal leishmaniasis: an open clinical trial and case-control study protocol

INTRODUCTION

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatological complication that occurs primarily among treated visceral leishmaniasis (VL) patients, and sporadically in a few without a history of VL. It mostly affects children and adolescents but is also common in adults. The conventional treatment with 120 intramuscular injections of sodium stibogluconate (SSG) is phasing out. Miltefosine (MF) is the only eventual alternative to SSG; however, its efficacy and safety profiles for treatment of children and adolescents with PKDL are lacking. In addition, risk factors for PKDL are poorly investigated. Host genetic, nutritional and environmental factors could be potential risk factors. As such, here we propose to evaluate the efficacy and safety of MF for 12 weeks at an allometric dose for children and adolescents with PKDL, and also to explore potential risk factors for PKDL.

METHODS AND ANALYSIS

A cross-sectional survey will look for suspected participants with PKDL among treated VL children and adolescents, a subsequent open clinical trial with MF at allometric dose, with a follow-up at 12 months. A case-control study will be carried out for PKDL risk factors. Assuming 95% cure rate, 95% CI and α=0.05, a sample size of 73 children with PKDL is needed. Considering an attrition rate of 10%, the final sample size is 80 children in each group. Descriptive and analytical analyses will be performed. Primary outcome is safety and cure rate of 12 weeks of treatment with MF.

ETHICS AND DISSEMINATION

International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) Ethical Review Committee (ERC) approved the protocol (PR#013045). Written informed consent will be taken from all participants and their guardians (in case of minor). A Data and Safety Monitoring Board (DSMB) of ICDDR,B ERC will monitor all study activities to ensure the safety of the participants.

TRIAL REGISTRATION NUMBER

NCT02193022; Pre-results.

Inferring the fluoride hydrogeochemistry and effect of consuming fluoride-contaminated drinking water on human health in some endemic areas of Birbhum district, West Bengal

This research work is carried out to evaluate fluoride (F) hydrogeochemistry and its effect on the population of two endemic villages of Birbhum district, West Bengal. Fluoride concentration in drinking water varies from 0.33 to 18.08 mg/L. Hydrogeochemical evolution suggests that ion-exchange mechanism is the major controlling factor for releasing F in the groundwater. Most of the groundwater samples are undersaturated with respect to calcite and fluorite. Health survey shows that out of 235 people, 142 people suffer from dental fluorosis. According to fluoride impact severity, almost 80 and 94 % people in an age group of 11-20 and 41-50 suffer from dental and skeletal fluorosis, respectively. Statistically drinking water F has a positive correlation with dental and skeletal fluorosis. Bone mineral density test reveals that 33 and 45 % of the studied population suffer from osteopenic and osteoporosis disease. IQ test also signifies that F has a bearing on the intelligence development of the study area school children. The existence of significant linear relationship (R (2) = 0.77) between drinking water F and urinary F suggests that consumption of F-contaminated drinking water has a major control over urinary F (0.39-20.1 mg/L) excretion.

Leishmania vaccine development: exploiting the host-vector-parasite interface

Visceral leishmaniasis (VL) is a disease transmitted by phlebotomine sand flies, fatal if untreated, and with no available human vaccine. In rodents, cellular immunity to Leishmania parasite proteins as well as salivary proteins of the sand fly is associated with protection, making them worthy targets for further exploration as vaccines. This review discusses the notion that a combination vaccine including Leishmania and vector salivary antigens may improve vaccine efficacy by targeting the parasite at its most vulnerable stage just after transmission. Furthermore, we put forward the notion that better modeling of natural transmission is needed to test efficacy of vaccines. For example, the fact that individuals living in endemic areas are exposed to sand fly bites and will mount an immune response to salivary proteins should be considered in pre-clinical and clinical evaluation of leishmaniasis vaccines. Nevertheless, despite remaining obstacles there is good reason to be optimistic that safe and effective vaccines against leishmaniasis can be developed.

Nanofiltration based water reclamation from tannery effluent following coagulation pretreatment

Coagulation-nanofiltration based integrated treatment scheme was employed in the present study to maximize the removal of toxic Cr(VI) species from tannery effluents. The coagulation pretreatment step using aluminium sulphate hexadecahydrate (alum) was optimized by response surface methodology (RSM). A nanofiltration unit was integrated with this coagulation pre-treatment unit and the resulting flux decline and permeate quality were investigated. Herein, the coagulation was conducted under response surface-optimized operating conditions. The hybrid process demonstrated high chromium(VI) removal efficiency over 98%. Besides, fouling of two of the tested nanofiltration membranes (NF1 and NF3) was relatively mitigated after feed pretreatment. Nanofiltration permeation fluxes as high as 80-100L/m(2)h were thereby obtained. The resulting permeate stream quality post nanofiltration (NF3) was found to be suitable for effective reuse in tanneries, keeping the Cr(VI) concentration (0.13mg/L), Biochemical Oxygen Demand (BOD) (65mg/L), Chemical Oxygen Demand (COD) (142mg/L), Total Dissolved Solids (TDS) (108mg/L), Total Solids (TS) (86mg/L) and conductivity levels (14mho/cm) in perspective. The process water reclaiming ability of nanofiltration was thereby substantiated and the effectiveness of the proposed hybrid system was thus affirmed.

Surface Modification of PMMA to Improve Adhesion to Corneal Substitutes in a Synthetic Core-Skirt Keratoprosthesis

Patients with advanced corneal disease do poorly with conventional corneal transplantation and require a keratoprosthesis (KPro) for visual rehabilitation. The most widely used KPro is constructed using poly(methyl methacrylate) (PMMA) in the central optical core and a donor cornea as skirt material. In many cases, poor adherence between the PMMA and the soft corneal tissue is responsible for device "extrusion" and bacterial infiltration. The interfacial adhesion between the tissue and the PMMA was therefore critical to successful implantation and device longevity. In our approach, we modified the PMMA surface using oxygen plasma (plasma group); plasma followed by calcium phosphate (CaP) coating (p-CaP); dopamine followed by CaP coating (d-CaP); or plasma followed by coating with (3-aminopropyl)triethoxysilane (3-APTES). To create a synthetic KPro model, we constructed and attached 500 μm thick collagen type I hydrogel on the modified PMMA surfaces. Surface modifications produced significantly improved interfacial adhesion strength compared to untreated PMMA (p < 0.001). The p-CaP group yielded the best interfacial adhesion with the hydrogel (177 ± 27 mN/cm(2)) followed by d-CaP (168 ± 31 mN/cm(2)), 3-APTES (145 ± 12 mN/cm(2)), and plasma (119 ± 10 mN/cm(2)). Longer-term stability of the adhesion was achieved by d-CaP, which, after 14 and 28 days of incubation in phosphate buffered saline, yielded 164 ± 25 mN/cm(2) (p = 0.906 compared to adhesion at day 1) and 131 ± 20 mN/cm(2) (p = 0.053), respectively. In contrast, significant reduction of adhesion strength was observed in p-CaP group over time (p < 0.001). All surface coatings were biocompatible to human corneal stromal fibroblasts, except for the 3-APTES group, which showed no live cells at 72 h of culture. In contrast, cells on d-CaP surface showed good anchorage, evidenced by the expression of focal adhesion complex (paxillin and vinculin), and prominent filopodia protrusions. In conclusion, d-CaP can not only enhance and provide stability to the adhesion of collagen hydrogel on the PMMA surface but also promote biointegration.