A THz graphene metasurface for polarization selective virus sensing.

We propose a novel method to exploit chirality of highly sensitive graphene plasmonic metasurfaces to characterize complex refractive indexes (RI) of viruses by detecting the polarization state of the reflected electric fields in the THz spectrum. A dispersive graphene metasurface is designed to produce chiral surface currents to couple linearly polarized incident fields to circularly polarized reflected fields. The metasurface sensing sensitivity is the result of surface plasmon currents that flow in a chiral fashion with strong intensity due to the underlying geometrical resonance. Consequently, unique polarization states are observed in the far-field with the ellipticity values that change rapidly with the analyte's RI. The determination of bimolecular RI is treated as an inverse problem in which the polarization states of the virus is compared with a pre-calculated calibration model that is obtained by full-wave electromagnetic simulations. We demonstrate the polarization selective sensing method by RI discrimination of three different types of Avian Influenza (AI) viruses including H1N1, H5N2, and H9N2 is possible. Since the proposed virus characterization method only requires determination of the polarization ellipses including its orientation at monochromatic frequency, the required instrumentation is simpler compared to traditional spectroscopic methods which need a broadband frequency scan.

Development and performance assessment of new solar and fuel cell-powered oxygen generators and ventilators for COVID-19 patients.

In this study, a new solar-based fuel cell-powered oxygenation and ventilation system is presented for COVID-19 patients. Solar energy is utilized to operate the developed system through photovoltaic panels. The method of water splitting is utilized to generate the required oxygen through the operation of a proton exchange membrane water electrolyser. Moreover, the hydrogen produced during water splitting is utilized as fuel to operate the fuel cell system during low solar availability or the absence of solar irradiation. Transient simulations and thermodynamic analyses of the developed system are performed by accounting for the changes in solar radiation intensities during the year. The daily oxygen generation is found to vary between 170.4 kg/day and 614.2 kg/day during the year. Furthermore, the amount of daily hydrogen production varies between 21.3 kg/day and 76.8 kg/day. The peak oxygen generation rate attains a value of 18.6 g/s. Moreover, the water electrolysis subsystem entails daily exergy destruction in the range of 139.9-529.7 kWh. The maximum efficiencies of the developed system are found to be 14.3% energetically and 13.4% exergetically.

Development and analysis of a new renewable energy-based industrial wastewater treatment system.

In this research study, a new solar energy-based integrated system is developed for treating industrial brine wastewater. An integrated solar-powered evaporation and membrane-based water treatment technique is utilized. Both forced convection as well as falling film evaporators are incorporated to treat high-concentration rejected brine. The system performance is assessed through a comprehensive thermodynamic investigation at varying operating parameters. The energetic performance is evaluated to vary from 12.5% to 15.9% across the year. Furthermore, the peak efficiency in terms of exergy is found to be 11.1%. Also, the membrane-based wastewater treatment subsystem is found to entail an energetic performance of 73.3% and an exergetic performance of 34.6% in terms of efficiencies. Moreover, an energetic performance of 15.4% and an exergetic performance of 2.9% is found for the evaporation-based subsystem. The exergy destructions in each system component are evaluated and the power generation subsystem is determined to have the highest exergy destruction rate of 15.4 MW. To investigate the effects of varying design parameters and operating conditions on the system performance, several parametric studies are also performed.

Holographic three-dimensional telepresence using large-area photorefractive polymer.

Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms and the absence of large-area and dynamically updatable holographic recording media have prevented realization of the concept. Here we use a holographic stereographic technique and a photorefractive polymer material as the recording medium to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

Dieulafoy's lesion: an overview.

Dieulafoy's lesion accounts for 1-5.8% of cases of acute upper GI bleeding. The two largest retrospective series, both from North America, found Dieulafoy's lesion as the source of hemorrhage in 1.9% and 1.2% of all endoscopies performed for acute GI bleeding. In the prospective study of Chung et al., Dieulafoy's Lesion was found in 3.4% of all patients with acute GI bleeding referred to their unit. The Dieulafoy's Lesion accounted for up to 40% of all causes of nonvariceal upper GI bleeding not caused by gastric or duodenal ulceration or esophageal varices in the prospective study of Matsui et al. In the study of Schmulewitz and Bailli, colonic Dieulafoy's Lesion were only found in 0.09% of all colonoscopies performed for lower GI bleeding. The actual incidence of both upper and lower GI bleeding from Dieulafoy's Lesion is likely higher than estimated because the diagnosis remains difficult. Recent advances in endoscopy have led to an increased detection of Dieulafoy's lesions. Initial GI endoscopy is effective in diagnosing up to 70% of patients. Several endoscopies may be required with 6% of patients, requiring three or more to establish the diagnosis. Angiography and/or red cell scanning can be used when endoscopy fails to diagnose a doubtful case. There is no definite unique policy for the treatment of Dieulafoy's lesions. Therapeutic endoscopy remains the first line of treatment option for controlling the bleeding while angiography is considered as a valuable alternative. Surgical intervention is kept for failure cases where it should be guided by preoperative localization. The mortality rate has decreased dramatically from 80% to 8.6% in recent times due to advancement in both diagnostic and therapeutic tools.

Ventral free oral mucous membrane graft for bulbar urethral stricture.

The use of oral mucous membrane graft onlay urethroplasty represents the most widespread method of bulbar urethral stricture repair. We investigated the short term result of oral mucous membrane graft placed on the ventral surface for management of bulbar urethral stricture. Patients with Bulbar urethral stricture of any length, infection free urinary tract and informed consent for oral mucosa harvesting and urethroplasty were selected for study. We enrolled 108 cases of bulbar urethral stricture patients from January 2004 to July 2009. The mean ± SD preoperative maximum flow rate of 5.2 ± 2.6 ml/sec and mean ± SD PVR 87 ± 58.3 ml were treated by substitution urethroplasty with oral mucous membrane by a single surgical team in a private hospital. Causes of stricture were trauma 26(24.1%), infection 58(53.7%), catheter induced 8(7.4%), post TURP 11(10.2%) and unknown 5(4.6%). Oral mucous membrane was harvested from the cheek or from the inner side of lower lip. Defect of the urethra displayed by longitudinal ventral urethrotomy and the graft was sutured over the edges of the incised urethral mucosa over a 14 Fr latex Foley's catheter. Spongiosum tissue was closed over the graft. Pericatheter urethrogram was performed in all cases to check for the anastomotic leakage and the Catheter was removed after 2 weeks of the procedure. After removal of catheter uroflowmetry & ultrasound scan of bladder were performed to estimate the maximum flow rate and post voidal residue. The patient was followed-up every 3 months with uroflowmetry & ultrasonography. The median (range) age of the patients was 32(21-72) years. Mean follow up period was 36 months (range 12-54). Mean ± SD stricture length was 3.7 ± 2.6 cm. The overall success rate was 91.7%. Mean ± SD flow rate was 23 ± 4.2 ml/sec, mean ± SD post void residue was 25 ± 15.5 ml and patient quality of life (QOL) was excellent in almost all patients. Overall complications were seen in 9(8.3%) cases. Of which, restricture occurred in 6 patients; periurethral fistulae seen in 2 cases and per urethral bleeding in 1 patient. No significant complications were observed at the donor site. Oral numbness and mild discomfort complained by 67.6% patients which were managed by reassurance only. In our experience ventral placement of oral mucous membrane graft along with spongioplasty is a very easy procedure with very encouraging short term result.

Post-Operative Severe Hyperbilirubinemia: A Case Report.

Hyperbilirubinemia is commonly seen in medical practice. But what could be the highest level of bilirubin in an individual that is still an unanswered question. We came across to a 37 years old lady in October 2018 with hepaticolithiasis who underwent extended choledocholithotomy. Her preoperative serum bilirubin was within normal range. Post-operatively she developed cholangitis and from 3rd post-operative day onwards she developed severe hyperbilirubinemia, which was high as 70.47 mg/dl on the 6th post-operative day. Other causes of post-operative hyperbilirubinemia were excluded. She was managed conservatively for this hyperbilirubinemia and bilirubin level gradually reduced.

A case of renal infarction associated with elevated factor VIII level.

Elevated factor VIII level has recently been shown to be associated with increased risk of thrombosis. We report here a case of renal infarction in association with elevated factor VIII level. The patient presented with a three-day history of flank pain. Laboratory studies on presentation showed an elevated serum creatinine concentration and microscopic hematuria. He was found to have bilateral pulmonary emboli and left common femoral vein thrombosis; imaging studies showed evidence of renal arterial thrombosis with infarction. Hypercoagulability assessment showed an elevated factor VIII level. He was treated with heparin and warfarin with significant improvement in his renal function. Consideration should be given to measurement of factor VIII level as a part of the workup of unexplained thrombo-embolic events.

A Rare Case of Insulinoma: A Case Report.

Insulinoma is a rare variety of endocrine neoplasm and is usually benign, solitary, and small in size. The hallmark of this disorder is high endogenous insulin secretion resulting in development of symptoms of hypoglycemia. Insulinomas account for 60% of islet cell tumors (ICT) of the pancreas. Ninety percent (90%) of the insulinomas measure less than 2cm. Early localization of the disease is essential to prevent lethal hypoglycemia. Here we report a case of insulinoma in a 28 year old female who subsequently underwent distal pancreatectomy with splenectomy on February 2017 in Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh.

A study on gender-related differences in laboratory characteristics of dengue fever.

Studies have reported significant gender-related differences in serological tests for detection of NS1 antigen and IgM antibody used for diagnosing dengue fever. However, no such study has been undertaken in India though dengue fever is endemic in this country. Therefore, this study was planned to study the association of serological findings with gender in 700 patients suspected to be suffering from dengue fever in the Indian setting. Haematological parameters of seropositive patients were also studied. Seropositivity and haemorrhagic findings were significantly associated with the female gender. Positive NS1 antigen and IgM antibody results were significantly associated with females and males, respectively.

Physicochemical, physiological, and mathematical considerations in optimizing percutaneous absorption of drugs.

The percutaneous absorption or transdermal permeation of drugs has gained considerable prominence in recent years through the development of transdermal systemic delivery systems and the related interest in the design and use of topical products. The present review discusses the phenomenon of percutaneous absorption in drug delivery and its importance in regard to the anatomy of skin, its physiological function, and biomechanical properties, as well as the physicochemical properties of the skin and the drug. The mathematical relationships and models used to describe the phenomenon of percutaneous absorption are also reported. The importance of these factors in optimizing percutaneous absorption or transdermal permeation of drugs for local or systemic effect is also discussed.

Nonparenteral administration of peptide and protein drugs.

Peptides/proteins are an important class of drugs which are usually administered by parenteral route. In recent years, pharmaceutical research has been directed towards developing a nonparenteral route of delivery of peptide/protein drugs. These studies report that it may be possible to administer the peptides/proteins especially insulin, by nasal, buccal, rectal, or even transdermal route. Therefore, there is a great potential for future development of a nonparenteral route of delivery of peptide/protein drugs. The primary objective of this review is to report the present status of research involving nonparenteral administration of macromolecular peptides/proteins, with special emphasis on insulin.

The patterns and predictors of smokeless tobacco onset among urban public school teenagers.

This study describes the patterns and predictors of smokeless tobacco (ST) use in a large sample of urban public school students in Los Angeles and San Diego. The use of ST is more common among men than women and among Caucasians than African Americans, Hispanics, and others. Approximately 20% of the male respondents and 5% of the female respondents reported use of ST at least once, and 10.1% of male students and 3.1% of female students who had never tried ST by seventh grade started to use it by eighth grade. Among Caucasians, about 30% of boys reported trying ST at least once and 13.7% of those who had never used ST by seventh grade initiated experimentation by eighth grade. These data are used to examine the family, peer, and intrapersonal predictors of ST onset. The family risk factors for ST onset include living with a single parent, parent-child conflicts, and parental alcohol use. The peer risk factors for ST use include peer drug use and activities with friends, such as parties and participation in sports. The intrapersonal risk factors include poor grades in school, risk taking, and stress. The study also shows that those who use cigarettes, alcohol, or marijuana are at higher risk of using ST and vice versa. This study supports a problem-prone behavior perspective of ST use and cigarette smoking. We suggest that both products be targeted because the same programs are likely to apply to both products to counteract problem-prone type variables. Medical Subject Headings (MeSH): tobacco, smokeless chewing tobacco, adolescent behavior.

Random-effects regression analysis of correlated grouped-time survival data.

Random-effects regression modelling is proposed for analysis of correlated grouped-time survival data. Two analysis approaches are considered. The first treats survival time as an ordinal outcome, which is either right-censored or not. The second approach treats survival time as a set of dichotomous indicators of whether the event occurred for time periods up to the period of the event or censor. For either approach both proportional hazards and proportional odds versions of the random-effects model are developed, while partial proportional hazards and odds generalizations are described for the latter approach. For estimation, a full-information maximum marginal likelihood solution is implemented using numerical quadrature to integrate over the distribution of multiple random effects. The quadrature solution allows some flexibility in the choice of distributions for the random effects; both normal and rectangular distributions are considered in this article. An analysis of a dataset where students are clustered within schools is used to illustrate features of random-effects analysis of clustered grouped-time survival data.

Physical factors affecting microencapsulation by simple coacervation of gelatin.

Gelatin has been coacervated at 60 degrees C using sodium sulphate. Interfacial tensions between coacervate and supernatant liquid, coacervate and two oils (with and without one of two drugs, clofibrate and chlormethiazole) and supernatant liquid and the oils (+/- drug) have been measured by a drop volume technique, in the presence and absence of one of three surfactants, cetrimide, sodium lauryl sulphate and hexadecyltrimethylammonium lauryl sulphate (double salt). Spreading coefficients calculated from tensions indicate that coacervate should spread readily over oil droplets in presence of double salt, less readily with cetrimide and spreading is unlikely in the presence of sodium lauryl sulphate. The sign of the charge on coacervate droplets and oil droplets was identified under different conditions and showed coacervate droplets and oil droplets have opposite charges except in the presence of sodium lauryl sulphate. Microcapsules were prepared using cetrimide or 'double salt' as emulsifier and release of drug measured. Those prepared with 'double salt' released more slowly than those prepared with cetrimide.

Iontophoretic transport of weak electrolytes through the excised human stratum corneum.

The effect of iontophoresis on the rate of permeation of a number of therapeutically active weak acids and bases through excised human stratum corneum has been examined, over a range of pH values. It has been shown that the amount of ionized drug species present in the drug solution is an important factor in the delivery of acids and bases by this route and that the molecular weight of the drug does not influence the rate of delivery by iontophoresis.

The effect of iontophoresis and vehicle pH on the in-vitro permeation of lignocaine through human stratum corneum.

The effect of iontophoresis and the pH of aqueous vehicles on the rate and extent of permeation of lignocaine through excised human stratum corneum was investigated. In the absence of iontophoresis, the rate of penetration was greatest at the higher pH values where lignocaine exists mainly in the unionized form; iontophoresis was most effective at the lower pH values where lignocaine is mainly ionized. At pH 3.4, and 5.2, the flux increased during iontophoresis, by approximately 8.5 and 4 times, respectively, relative to that occurring without iontophoresis. The present results suggest that some weak electrolytes which show poor percutaneous penetration may be administered topically using iontophoresis provided the drug is kept in a highly ionized form.

Differential influence of parental smoking and friends' smoking on adolescent initiation and escalation of smoking.

Smoking-related behaviors and attitudes of significant others (especially friends and parents) are among the most consistent predictors of adolescent smoking. However, theorists remain divided on whether the behaviors of significant others influence adolescent smoking directly or indirectly, and the relative influence of parental and peer smoking on adolescents' own smoking is still a matter of debate. In addition, little research has examined the role of significant others' behavior on different stages of smoking onset. In particular, not much information is available regarding gender and ethnic differences in social influences on smoking behavior. We use structural equation modeling to address these issues. Different theoretical perspectives from cognitive-affective theories (Ajzen 1985; Ajzen and Fishbein 1980) and social learning theories (Akers et al. 1979; Bandura 1969, 1982, 1986) have been integrated into a structural model of smoking influence. The results show that friends' smoking affects adolescent initiation into smoking both directly and indirectly, whereas parental smoking influences smoking initiation only indirectly. The data also show that friends' and parents' smoking affect smoking escalation only indirectly. In general, friends' smoking has a stronger effect on adolescents' smoking behavior, particularly on initiation. Multiple group comparisons of the structural models predicting smoking initiation among males and females reveal that parental approval of smoking plays a significant mediating role for females, but not for males. Comparisons of Whites, Blacks, Hispanics, and other ethnic groups reveal that there are some significant differences in the pathways of friends' influences among the four groups.

Patterns of use of smokeless tobacco and the unidimensional model of drug involvement.

The present study tested whether smokeless tobacco (ST) fits a unidimensional model of drug involvement and tried to locate ST along the dimension that underlies drug use. The latent trait analysis was employed to quantify drug involvement in a sample of high school students. Analyses showed that although ST use fits the unidimensional model of drug involvement, the place of ST use along the continuum of drug involvement is not stable and differs by gender and ethnicity. Particularly for males, ST use is likely to be preceded by soft drug use and followed by hard drug use; for females, however, ST use is closely associated with hard drug use. The analyses also revealed that the fit of the unidimensional model and the location of ST use along the dimension vary with different ethnic groups.

Accuracy of urine collection methods compared to measured GFR in adults with liver disease.

BACKGROUND: Assessment of kidney function is necessary to stage kidney disease, dose medications, and to make decisions about organ allocation. Estimating equations that incorporate serum creatinine (SCr) are not consistently reliable. However, assessment of creatinine clearance (CrCl) using 24-hour urine collection methods is also prone to errors. The purpose of this study was to evaluate the accuracy of measured CrCl determined using shorter urine collection times compared to glomerular filtration rate measured by (125)I-iothalamate clearance ((125)I-CL) in patients with liver disease. METHODS: Adult patients with chronic liver disease were enrolled. All patients received (125)I-iothalamate and had a catheter placed for urine collection. Blood samples were collected at designated times over 8 hours to determine (125)I-CL. CrCl was determined from a 1-hour and a 4-hour urine collection and compared to (125)I-CL. RESULTS: Characteristics of the eight patients enrolled included age 52 ± 6 years; SCr 1.2 ± 0.4 mg/dL; and Model for End-stage Liver Disease score of 13 ± 3. All patients were Child-Pugh Class B. Mean estimates of kidney function (mean ± SD, mL/min/1.73 m(2)) by method were 74 ± 38 for (125)I-CL, 79 ± 28 for the 1-hour urine collection, and 72 ± 26 for the 4-hour urine collection. Measured CrCl did not differ significantly from (125)I-CL (P = .641 for 1-hour CrCl versus (125)I-CL, and P = 1.0 for the 4-hour CrCl versus (125)I-CL). CONCLUSION: When urine collection methods are necessary for an individualized assessment of kidney function, shorter collection times can provide accurate results and would be more feasible for the patient.