On lithium doping in two stable nano-flakes of the B24: The double-ring versus the quasiplanar configuration.

The stable local minima due to the addition of the Li atom to the double-ring and the quasiplanar configurations of the B24 molecule have been searched on the doublet potential energy surface to reveal the structural and electronic features of the Li@B24 system. We report two and seven stable local minima without imaginary vibrational frequency for the Li@B24(double-ring) and the Li@B24(quasiplanar) systems, respectively. The criteria of the adsorption energy, the vertical ionization (VI) energy, the deformation energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap, the atomic charges, the spin density distribution, the electron transfer (ET), atoms in molecules (AIM) analysis and the nonlinear optical (NLO) properties have been investigated for all the reported molecules of the Li@B24 system in the present paper. Our results present that both thermodynamic and chemical stability of the Li atom doping to the quasiplanar configuration of the B24 molecule are more than those of the double-ring configuration. Additionally, both the double-ring and the quasiplanar configurations can produce the Li@B24 system with values of high first hyperpolarizability (ßtotal) due to the Li atom doping. In all the reported molecules of the Li@B24 system, electron density of the Li atom decreases due to the existence of the double-ring and the quasiplanar configurations confirming the role of the electron donor for the Li atom. In contrast, both decreasing and increasing electron density have been observed in the B atoms of the Li@B24 system. However, the role of electron acceptor (increasing electron density) for the B atoms is more dominant than the role of electron donor (decreasing electron density). This result highlights chemical flexibility of the B atoms.

A DFT study on graphene, SiC, BN, and AlN nanosheets as anodes in Na-ion batteries.

A great concern exists about the lifetime, cost, low-temperature performance, and safety of Li-ion batteries. Na-ion batteries (NIB) are an alternative to the Li-ion batteries due to the wide availability of sodium, its low cost, and nontoxicity. Here, we examined the Na and Na+ adsorption on nanosheets of carbon (graphene), AlN, BN, and SiC to explore their potential use as an anode in NIBs. The interaction of atomic Na was found to play the main role in producing different nanosheet cell voltages. Unlike the graphene and SiC nanosheets, the lone pairs on the surface of the AlN and BN nanosheets hinder the Na adsorption and significantly increase the cell voltage. The order of magnitude of the nanosheet cell voltage as an anode in NIBs is as follows: AlN (1.49 V) > BN (1.46 V) > > C (0.69 V) > SiC (0.61 V). The AlN and BN nanosheets may be appropriate compounds for NIBs and their cell voltages are comparable with carbon nanotubes.

A DFT study on the central-ring doped HBC nanographenes.

Nanographenes (NGs) are a segment of graphene whose dangling bonds are saturated with hydrogen atoms, introducing different properties and promising applications. Here we investigate the electronic, thermodynamic, optical, and structural properties of four C36X3Y3H18 NGs (X=B, and Al; and Y=N, and P) based on the density functional theory calculations. It was mainly found that 1) BN-NG is planar molecule and the others are buckybowl-shaped ones, 2) The bowl-to-bowl inversion Gibbs free energies (ΔG#) of buckybowl shaped NGs are very huge and the rate constant is very small, hindering the inversion, 3) The relative energetic stability order based on the standard enthalpy of formation (ΔHf°) is as BN>AlN>BP>AlP, which the BN, and AlN doped NGs are stable at room temperature but the BP and AlP doped ones are instable, 4) The electrical conductivity order of magnitude is inverse of that of stability, 5) An exciton binding energy is predicted in the range of 0.57-0.75eV for the NGs which corresponds to Frenkel exciton type, 6) the NGs are not soluble in organic solvent in agreement with the experimental results and is partially soluble in water solvent with Gibbs free energy of solvation (ΔGsolv) in the range of -6.1 to -10.1kcal/mol.

Selective detection of cyanogen halides by BN nanocluster: a DFT study.

The electronic sensitivity and adsorption behavior toward cyanogen halides (X-CN; X = F, Cl, and Br) of a B12N12 nanocluster were investigated by means of density functional theory calculations. The X-head of these molecules was predicted to interact weakly with the BN cluster because of the positive σ-hole on the electronic potential surface of halogens. The X-CN molecules interact somewhat strongly with the boron atoms of the cluster via the N-head, which is accompanied by a large charge transfer from the X-CN to the cluster. The change in enthalpy upon the adsorption process (at room temperature and 1 atm) is about -19.2, -23.4, and -30.5 kJ mol-1 for X = F, Cl, and Br, respectively. The LUMO level of the BN cluster is largely stabilized after the adsorption process, and the HOMO-LUMO gap is significantly decreased. Thus, the electrical conductivity of the cluster is increased, and an electrical signal is generated that can help to detect these molecules. By increasing the atomic number of X, the signal will increase, which makes the sensor selective for cyanogen halides. Also, it was indicated that the B12N12 nanocluster benefits from a short recovery time as a sensor.

Na-ion batteries based on the inorganic BN nanocluster anodes: DFT studies.

It has been recently indicated that the Li-ion batteries may be replaced by Na-ion batteries because of their low safety, high cost, and low-temperature performance, and lack of the Li mineral reserves. Here, using density functional theory calculations, we studied the potential application of B12N12 nanoclusters as anode in Na-ion batteries. Our calculations indicate that the adsorption energy of Na+ and Na are about -23.4 and -1.4kcal/mol, respectively, and the pristine BN cage to improve suffers from a low cell voltage (∼0.92V) as an anode in Na-ion batteries. We presented a strategy to increase the cell voltage and performance of Na-ion batteries. We showed that encapsulation of different halides (X=F-, Cl-, or Br-) into BN cage significantly increases the cell voltage. By increasing the atomic number of X, the Gibbs free energy change of cell becomes more negative and the cell voltage is increased up to 3.93V. The results are discussed based on the structural, energetic, frontier molecular orbital, charge transfer and electronic properties and compared with the performance of other nanostructured anodes.

Genetic diversity of HCV among various high risk populations (IDAs, thalassemia, hemophilia, HD patients) in Iran.

OBJECTIVE: To determine the patterns of distribution of HCV genotypes among high risk population in north of Iran. METHODS: A cross-sectional study was conducted on 135 HCV RNA-positive high risk individuals including thalassemia, hemophilia, patients under hemodialysis and intravenous drug addicts. HCV genotypes were determined based on amplification with type-specific primers methods. RESULTS: Among the 187 anti-HCV positive samples, only 135 (72.2%) gave HCV-RNA positvity. Over all, the most identified HCV type was genotype 3a (51.1%) followed by 1a (27.4%), 1b (8.2%). Sixteen (11.9%) out of 135 HCV RNA-positive participants have infected with more than one genotype or subtypes as follow; 1a/1b in 11 (8.2%), 2/3a in 3 (2.2%), and 1a/1b/3a in 2 (1.5%). Stratification of participants revealed that HCV subtype 3a was more prominent in thalassemia, hemophilia and HD patients but 1a and 1b were frequent in intravenous drug addicts. CONCLUSIONS: This study is the first report on HCV genotypes among Iranian subjects with different exposure categories resided in Mazandaran, where genotype 3a was found to be the most frequent genotype in thalassemia, hemophilia, and hemodialysis patients but not in IDAs. Since the addiction age is decreasing in Iran and a lot of addicts are IDAs, it might change the subtype pattern of HCV in general population.

Aluminum phosphide poisoning known as rice tablet: A common toxicity in North Iran.

BACKGROUND: Aluminum phosphide (ALP) is a highly effective insecticide and rodenticide used frequently to protect stored grain. Acute poisoning with this compound is common in some countries including India and Iran, and is a serious health problem. AIM: The objective of this study was to survey ALP poisoning locally known as "Rice Tablet" and the outcome in a referral poisoning hospital in Mazandaran province, northern part of Iran. MATERIALS AND METHODS: The study was a cross-sectional study from March 2007 to February 2008. Records of all patients admitted and hospitalized to a referral teaching hospital during the 2 year period were collected. Information including gender, age, cause of toxicity, amount of AIP consumed, route of exposure, time between exposure and hospital admission, signs and symptoms of toxicity at admission, therapeutic intervention, laboratory tests, and outcome were extracted from the patients' notes. Patients who died and survived were compared using appropriate statistical tests. RESULTS: During the two-year period, 102 patients, 46 men and 56 women with mean (±SD) age 28.5 ± 12.4 year were admitted with ALP poisoning. The most common signs and symptoms at admission were nausea (79.4%), vomiting (76.5%), and abdominal pain (31.4%). 41.1% of the patients showed metabolic acidosis. Suicidal intention was the most common cause of poisoning (97%) leading to 19 (18.6%) deaths. Compared with the patients who survived, those who died had taken higher amount of ALP tablet (2.2 ± 2.4 vs. 1.4 ± 1.0, P < 0.05), had poor liver function test (P < 0.0001) and severe metabolic acidosis (pH: 7.17 ± 0.19 vs. 7.33 ± 0.08, P < 0.0001). CONCLUSION: ALP poisoning is a common toxicity in Iran causing high morality. This is a serious health problem in agricultural region where ALP is readily available. Withdrawal of ALP tablet from the market and introduction of safer products as rodenticides and insecticides is recommended.

Prospective evaluation of selective lymph node biopsy for cutaneous malignant melanoma.

Some patients presenting with cutaneous malignant melanoma without palpable adenopathy have regional metastatic disease. We have applied the technique of gamma probe-directed selective lymph node biopsy and used the results to direct further therapy. The results of a prospective nonrandomized clinical study are presented. Between November 1993 and December 1996, 63 patients with a diagnosis of primary cutaneous malignant melanoma underwent lymphoscintigraphy with technetium sulfur colloid followed by gamma probe-guided lymph node biopsy. There were 32 (51%) women and 31 (49%) men with a mean age of 51.1 years (median, 50; range, 13-87). Mean Breslow thickness was 2.13 mm (range, 0.5-15.0 mm; median, 1.56 mm). Primary locations were head and neck in 8 (13%), trunk in 24 (38%), upper extremity in 13 (21%), and lower extremity in 18 (29%). Selective lymph node biopsy was done on an outpatient basis with local anesthesia in 49 cases (78%) and in the operating room with general anesthetic in 14 patients (22%). One lymph node site was biopsied in 46 patients (73%), two sites in 16 (25%), and three in 1 (2%), for a total of 81 selective lymph node biopsy sites, mean 1.29 per patient. The mean number of labeled lymph nodes removed per site per patient was 1.64 (range, 1-5). Seroma or infection occurred in 6 patients (10%). Micrometastatic disease was identified in nine selective lymph node biopsy sites in eight patients. Of eight patients undergoing lymph node dissection, 5 (63%) had no additional pathological lymph node involvement. With a mean follow-up of 579 days from selective lymph node biopsy (median, 594; range, 36-1157), 59 (94%) have no evidence of disease. Three patients have died, 2 with systemic disease (475 and 1149 days) and 1 from a myocardial infarction (380 days). No patient has failed with regional-only recurrence. Gamma probe-directed selective lymph node biopsy is a straightforward procedure that can be done in the outpatient setting and facilitates management of patients with cutaneous malignant melanoma.

Peritoneal carcinomatosis with urachal signet-cell adenocarcinoma.

Urachal adenocarcinoma is an uncommon clinicopathologic entity associated with a dismal prognosis. We report a case of peritoneal carcinomatosis from urachal adenocarcinoma (signet cell type) treated with cytoreductive surgery and intraperitoneal hyperthermic chemotherapy (IPHC). Prior to treatment, disease had progressed with systemic chemotherapy. The patient remained free of symptomatic peritoneal disease or local recurrence but eventually died 23 months after IPHC and 31 months after diagnosis due to widespread bone metastases.

Fluid-sorption phenomena in sterilized polyethylene acetabular prostheses.

The weight changes due to fluid-sorption were measured in 62 radiation-sterilized acetabular sockets and 10 unsterilized discs. The materials included two types of ultra-high molecular weight (UHMW) polyethylene (RCH 1000; Hi-Fax 1900) and a carbon-fibre-reinforced polyethylene (CFPE). The fluid absorption curve was consistently biphasic. In the first 30 d soak-period (Phase 1), the initial rate of fluid absorption averaged 153 micrograms/d for conventional UHMW polyethylene and 278 micrograms/d for carbon-fibre-reinforced polyethylene. In Phase 2, beyond 30 d and up to 400 d, fluid absorption reduced to linear rates of 27 micrograms/d for UHMW polyethylene and 43 micrograms/d for CFPE. The latter soak-weight-gain values corresponded to only 0.00016%/d and 0.00034%/d respectively. There was little difference in absorption rates between sterilized and unsterilized samples. However soak rates were generally higher in water compared to serum.

Ovarian hyperandrogenism with normal and abnormal histologic findings of the ovaries.

Thirty-one patients with clinical features of polycystic ovary syndrome (PCO) were studied to determine the correlation between biochemical and histologic findings. The biochemical features investigated were the effects of adrenocortical and ovarian suppression by dexamethasone and oral contraceptives (Ovulen) on plasma free androgens. Four patients showed a histologic picture consistent with PCO (Group A), and five had histologically normal ovaries (Group B). The remaining 22 patients had no tissue available for histologic examination (Group C). The baseline values of plasma free testosterone (FTel) were higher and those of testosterone-binding globulin (TeBG) were lower (p less than 0.05) in Group A than in Group B, although plasma total testosterone (T) and the free 17beta-hydroxysteroid androgen index (FHSl) were similar in the two groups. During dexamethasone administration in all study groups, T and FTel fell slightly (17.7% to 33.8%), and FHSl levels decreased moderately (36% to 46.6%); in no case did both indices of free androgen levels fall to the normal range for dexamethasone-suppressed women. However, no change was noted in TeBG in all three groups. On the other hand, Ovulen treatment suppressed T and free androgens to normal in all groups, and raised TeBG more than 350% from the baseline. These data suggest a decrease in androgen production. The effects of dexamethasone and Ovulen on all three groups were similar in percent changes. As Group B patients resemble those of Group A biochemically and clinically, except for possibly being less hyperandrogenic, the concept of ovarian hyperandrogenism should be expanded to include patients with no anatomic ovarian abnormality, particularly in milder cases.

Immunoglobulins, proteinase inhibitors, albumin, and lysozyme in human cervical mucus. I. Communication: hormonal profiles and cervical mucus changes--methods and results.

The serum levels of luteinizing hormone (LH), estradiol-17beta, and progesterone were determined simultaneously with the concentrations of immunoglobulin (Ig) G, IgA, C'3, alpha1-antitrypsin, inter-alpha-trypsin inhibitor, alpha1x-antichymotrypsin, albumin, and lysozyme in cervical mucus during nine ovulatory cycles. Spinnbarkeit and ferning were also assessed, and the basal body temperature was measured and recorded during these cycles. The profiles were synchronized according to the LH peak. The midcycle period, characterized by the rapid increase and decline of estrogen and the beginning rise of progesterone, shows a prounced minimum of immunoglobulins, C'3, proteinase inhibitors, albumin, and lysozyme in cervical mucus, which is known to be most receptive to sperm penetration at this time. Although the variation of cervical mucus values is considerable during the early proliferative and the luteal phases, the midcycle values appear to be constantly low, showing slight differences among the profiles of the different parameters. The statistical evaluation and the assessment of the significance of parameters for ovulation detection and the assessment of the fertile period as well as the correlation of these parameters with basal body temperature will be the subject of the second communication of this series.

PIP: Methods and results of a study of 9 ovulatory cycles where luteinizing hormone, estradiol-17beta, and progesterone were determined simultaneously with the cervical mucus parameters are reported. Spinnbarkeit and ferning, and basal body temperature were also recorded. The midcycle period characterized by the rapid increase and decline of estrogen and the beginning rise of progesterone revealed a pronounced minimum of immunoglobulins, C'3-complement, proteinase inhibitors, albumin, and lysozyme in cervical mucus. The variation of cervical mucus values is considerable during the early proliferative and the luteal phases whereas the midcycle values appear to be constantly low, showing slight differences among the profiles of the different parameters.

Predetermination of ovulation timing by luteinizing hormone assay.

A modified rapid,solid-phase radioimmunoassay for serum luteinizing hormone requiring only 1 1/2 hours of incubation is presented. The method has been used to predetermine the time of ovulation in six infertile patients. Its advantages are presented in these cases. The simplicity and accuracy of the method make it practical, and it can serve well in the management of infertility.

Obesity and oligomenorrhea are associated with hyperandrogenism independent of hirsutism.

Obesity, oligomenorrhea, and hirsutism are frequently associated with high plasma androgen levels and/or low testosterone-binding globulin (TEBG) levels. Studied have been undertaken to determine the extent to which each of these clinical features may be related to this hormonal profile. Indexes of plasma free (unbound) androgen levels were focused upon because this fraction appears to be the biologically active portion of the plasma androgens. The hormonal profile was normal in women with either obesity or oligomenorrhea alone and abnormal in those with severe hirsutism alone. On striking new finding was that subjects with the combination of obesity and oligomenorrhea had elevated plasma total and free androgens and depressed TEBG even in the absence of hirsutism. Furthermore, the androgen levels were higher in obese oligomenorrheic women with mild hirsutism than in severely hirsute women who were not obese. Plasma estradiol concentrations were normal in these obese women. A simple explanation for elevated free plasma androgen levels in obese women who were oligomenorrheic yet had little if any hirsutism is not possible. The data are compatible with the concept that obesity is a variably expressed manifestation of slightly elevated plasma free androgen levels or that obesity is an incidental finding which somehow blunts the effect of high androgen levels on hair follicles. Regardless of the explanation, oligomenorrheic obese women must be suspected of having high androgen production even in the absence of hirsutism.