Plasticised chitosan: Dextran polymer blend electrolyte for energy harvesting application: Tuning the ion transport and EDLC charge storage capacity through TiO2 dispersion.

This study investigates the performance of biopolymer electrolytes based on chitosan and dextran for energy storage applications. The optimization of ion transport and performance of electric double-layer capacitors EDCL using these electrolytes, incorporating different concentrations of glycerol as a plasticizer and TiO2 as nanoparticles, is explored. Impedance measurements indicate a notable reduction in charge transfer resistance with the addition of TiO2. DC conductivity estimates from AC spectra plateau regions reach up to 5.6 × 10-4 S/cm. The electric bulk resistance Rb obtained from the Nyquist plots exhibits a substantial decrease with increasing plasticizer concentration, further enhanced by the addition of the nanoparticles. Specifically, Rb decreases from ∼20 kΩ to 287 Ω when glycerol concentration increases from 10 % to 40 % and further drops to 30 Ω with the introduction of TiO2. Specific capacitance obtained from cyclic voltammetry shows a notable increase as the scan rate decreases, indicating improved efficiency and stability of ion transport. The TiO2-enriched EDCL achieves 12.3 F/g specific capacitance at 20 mV/s scan rate, with high ion conductivity and extended electrochemical stability. These results suggest the great potential of plasticizer and TiO2 with biopolymers in improving the performance of energy storage systems.

Synthesis and Characterization of Polymers Containing Ethynylene and Ethynylene-Thiophene Based Alternating Polymers Containing 2,1,3-Linked Naphthothiadiazole Units as Acceptor Linked with Fluorine as Donor: Electrochemical and Spectroscopic Studies.

The effect of ethynylene or ethynylene-thiophene spacers on the band gap of alternating polymers, containing 4,9-naphthothiadiazole units as an acceptor and 2,7-linked fluorene repeat units as a donor, were investigated. The Sonogashira coupling reaction was employed to prepare the two novel copolymers, namely ((9,9-dioctyl-fluorene)-2,7-diethynylene-alt-4,9-2,1,3-naphthothiadiazole (PFDENT) and poly(5,5'-(9,9-dioctyl-fluorene-2,7-diyl)bis(ethynyl-2-thienyl)-alt-4,9-(2,1,3-naphthothiadiazole) (PFDTENT). The optical, electrochemical and thermal properties of the two obtained polymers were widely investigated and compared. Both resulting polymers showed low solubility in common organic solvents and moderate molecular weights. It is believed that the introduction of acetylene linkers rather than acetylene-thiophene spacers on the polymer chains reduces the steric hindrance between the donor and acceptor units which leads to the adoption of more planar structures of polymeric chains, resulting in decreased molecular weights of the resulting conjugated polymers. Thus, both ethynylene-based polymers and ethynylene-thiophene-based polymers showed red-shifted absorption maxima compared to their counterpart (thiophene-based polymer), owing to the adoption of more planar structures. Optical studies revealed that the new ethynylene and ethynylene-thiophene-based polymers displayed low band gaps compared to their thiophene analogue polymer PFDTNT. Both resulting polymers showed good thermal stability. X-ray diffraction (XRD) patterns of both polymers revealed that PFDENT and PFDTENT possessed an amorphous nature in solid state.

Studies of Circuit Design, Structural, Relaxation and Potential Stability of Polymer Blend Electrolyte Membranes Based on PVA:MC Impregnated with NH4I Salt.

This work presents the fabrication of polymer electrolyte membranes (PEMs) that are made of polyvinyl alcohol-methylcellulose (PVA-MC) doped with various amounts of ammonium iodide (NH4I). The structural and electrical properties of the polymer blend electrolyte were performed via the acquisition of Fourier Transform Infrared (FTIR) and electrical impedance spectroscopy (EIS), respectively. The interaction among the components of the electrolyte was confirmed via the FTIR approach. Electrical impedance spectroscopy (EIS) showed that the whole conductivity of complexes of PVA-MC was increased beyond the addition of NH4I. The application of EEC modeling on experimental data of EIS was helpful to calculate the ion transport parameters and detect the circuit elements of the films. The sample containing 40 wt.% of NH4I salt exhibited maximum ionic conductivity (7.01 × 10-8) S cm-1 at room temperature. The conductivity behaviors were further emphasized from the dielectric study. The dielectric constant, ε' and loss, ε'' values were recorded at high values within the low-frequency region. The peak appearance of the dielectric relaxation analysis verified the non-Debye type of relaxation mechanism was clarified via the peak appearance of the dielectric relaxation. For further confirmation, the transference number measurement (TNM) of the PVA-MC-NH4I electrolyte was analyzed in which ions were primarily entities for the charge transfer process. The linear sweep voltammetry (LSV) shows a relatively electrochemically stable electrolyte where the voltage was swept linearly up to 1.6 V. Finally, the sample with maximum conductivity, ion dominance of tion and relatively wide breakdown voltage were found to be 0.88 and 1.6 V, respectively. As the ions are the majority charge carrier, this polymer electrolyte could be considered as a promising candidate to be used in electrochemical energy storage devices for example electrochemical double-layer capacitor (EDLC) device.

The Study of Ion Transport Parameters in MC-Based Electrolyte Membranes Using EIS and Their Applications for EDLC Devices.

A solution cast technique was utilized to create a plasticized biopolymer-based electrolyte system. The system was prepared from methylcellulose (MC) polymer as the hosting material and potassium iodide (KI) salt as the ionic source. The electrolyte produced with sufficient conductivity was evaluated in an electrochemical double-layer capacitor (EDLC). Electrolyte systems' electrical, structural, and electrochemical properties have been examined using various electrochemical and FTIR spectroscopic techniques. From the electrochemical impedance spectroscopy (EIS), a maximum ionic conductivity of 5.14 × 10-4 S cm-1 for the system with 50% plasticizer was recorded. From the EEC modeling, the ion transport parameters were evaluated. The extent of interaction between the components of the prepared electrolyte was investigated using Fourier transformed infrared spectroscopy (FTIR). For the electrolyte system (MC-KI-glycerol), the tion and electrochemical windows were 0.964 and 2.2 V, respectively. Another electrochemical property of electrolytes is transference number measurement (TNM), in which the ion predominantly responsibility was examined in an attempt to track the transport mechanism. The non-Faradaic nature of charge storing was proved from the absence of a redox peak in the cyclic voltammetry profile (CV). Several decisive parameters have been specified, such as specific capacitance (Cs), coulombic efficiency (η), energy density (Ed), and power density (Pd) at the first cycle, which were 68 F g-1, 67%, 7.88 Wh kg-1, and 1360 Wh kg-1, respectively. Ultimately, during the 400th cycle, the series resistance ESR varied from 70 to 310 ohms.

A Mini Review on the Development of Conjugated Polymers: Steps towards the Commercialization of Organic Solar Cells.

This review article covers the synthesis and design of conjugated polymers for carefully adjusting energy levels and energy band gap (EBG) to achieve the desired photovoltaic performance. The formation of bonds and the delocalization of electrons over conjugated chains are both explained by the molecular orbital theory (MOT). The intrinsic characteristics that classify conjugated polymers as semiconducting materials come from the EBG of organic molecules. A quinoid mesomeric structure (D-A ↔ D+ = A-) forms across the major backbones of the polymer as a result of alternating donor-acceptor segments contributing to the pull-push driving force between neighboring units, resulting in a smaller optical EBG. Furthermore, one of the most crucial factors in achieving excellent performance of the polymer is improving the morphology of the active layer. In order to improve exciton diffusion, dissociation, and charge transport, the nanoscale morphology ensures nanometer phase separation between donor and acceptor components in the active layer. It was demonstrated that because of the exciton's short lifetime, only small diffusion distances (10-20 nm) are needed for all photo-generated excitons to reach the interfacial region where they can separate into free charge carriers. There is a comprehensive explanation of the architecture of organic solar cells using single layer, bilayer, and bulk heterojunction (BHJ) devices. The short circuit current density (Jsc), open circuit voltage (Voc), and fill factor (FF) all have a significant impact on the performance of organic solar cells (OSCs). Since the BHJ concept was first proposed, significant advancement and quick configuration development of these devices have been accomplished. Due to their ability to combine great optical and electronic properties with strong thermal and chemical stability, conjugated polymers are unique semiconducting materials that are used in a wide range of applications. According to the fundamental operating theories of OSCs, unlike inorganic semiconductors such as silicon solar cells, organic photovoltaic devices are unable to produce free carrier charges (holes and electrons). To overcome the Coulombic attraction and separate the excitons into free charges in the interfacial region, organic semiconductors require an additional thermodynamic driving force. From the molecular engineering of conjugated polymers, it was discovered that the most crucial obstacles to achieving the most desirable properties are the design and synthesis of conjugated polymers toward optimal p-type materials. Along with plastic solar cells (PSCs), these materials have extended to a number of different applications such as light-emitting diodes (LEDs) and field-effect transistors (FETs). Additionally, the topics of fluorene and carbazole as donor units in conjugated polymers are covered. The Stille, Suzuki, and Sonogashira coupling reactions widely used to synthesize alternating D-A copolymers are also presented. Moreover, conjugated polymers based on anthracene that can be used in solar cells are covered.

Characteristics of Plasticized Lithium Ion Conducting Green Polymer Blend Electrolytes Based on CS: Dextran with High Energy Density and Specific Capacitance.

The solution cast process is used to set up chitosan: dextran-based plasticized solid polymer electrolyte with high specific capacitance (228.62 F/g) at the 1st cycle. Fourier-transform infrared spectroscopy (FTIR) pattern revealed the interaction between polymers and electrolyte components. At ambient temperature, the highest conductive plasticized system (CDLG-3) achieves a maximum conductivity of 4.16 × 10-4 S cm-1. Using both FTIR and electrical impedance spectroscopy (EIS) methods, the mobility, number density, and diffusion coefficient of ions are measured, and they are found to rise as the amount of glycerol increases. Ions are the primary charge carriers, according to transference number measurement (TNM). According to linear sweep voltammetry (LSV), the CDLG-3 system's electrochemical stability window is 2.2 V. In the preparation of electrical double layer capacitor devices, the CDLG-3 system was used. There are no Faradaic peaks on the cyclic voltammetry (CV) curve, which is virtually rectangular. Beyond the 20th cycle, the power density, energy density, and specific capacitance values from the galvanostatic charge-discharge are practically constant at 480 W/Kg, 8 Wh/Kg, and 60 F g-1, for 180 cycles.

Plasticized Polymer Blend Electrolyte Based on Chitosan for Energy Storage Application: Structural, Circuit Modeling, Morphological and Electrochemical Properties.

Chitosan (CS)-dextran (DN) biopolymer electrolytes doped with ammonium iodide (NH4I) and plasticized with glycerol (GL), then dispersed with Zn(II)-metal complex were fabricated for energy device application. The CS:DN:NH4I:Zn(II)-complex was plasticized with various amounts of GL and the impact of used metal complex and GL on the properties of the formed electrolyte were investigated.The electrochemical impedance spectroscopy (EIS) measurements have shown that the highest conductivity for the plasticized system was 3.44 × 10-4 S/cm. From the x-ray diffraction (XRD) measurements, the plasticized electrolyte with minimum degree of crystallinity has shown the maximum conductivity. The effect of (GL) plasticizer on the film morphology was studied using FESEM. It has been confirmed via transference number analysis (TNM) that the transport mechanism in the prepared electrolyte is predominantly ionic in nature with a high transference number of ion (ti)of 0.983. From a linear sweep voltammetry (LSV) study, the electrolyte was found to be electrochemically constant as the voltage sweeps linearly up to 1.25 V. The cyclic voltammetry (CV) curve covered most of the area of the current-potential plot with no redox peaks and the sweep rate was found to be affecting the capacitance. The electric double-layer capacitor (EDLC) has shown a great performance of specific capacitance (108.3 F/g), ESR(47.8 ohm), energy density (12.2 W/kg) and power density (1743.4 W/kg) for complete 100 cycles at a current density of 0.5 mA cm-2.

Fabrication of Alternating Copolymers Based on Cyclopentadithiophene-Benzothiadiazole Dicarboxylic Imide with Reduced Optical Band Gap: Synthesis, Optical, Electrochemical, Thermal, and Structural Properties.

A series of alternating copolymers containing cyclopentadithiophene (CPDT) flanked by thienyl moieties as electron-donor units and benzothiadiazole dicarboxylic imide (BTDI) as electron-acceptor units were designed and synthesized for solar cell applications. Different solubilizing side chains, including 2-ethylhexyl chains and n-octyl chains were attached to CPDT units, whereas 3,7-dimethyloctyl chains and n-octyl chains were anchored to the BTDI moieties. The impact of these substituents on the solubilities, molecular weights, optical and electrochemical properties, and thermal and structural properties of the resulting polymers was investigated. PCPDTDTBTDI-EH, DMO was synthesized via Suzuki polymerization, whereas PCPDTDTBTDI-8, DMO, and PCPDTDTBTDI-EH, 8 were prepared through direct arylation polymerization. PCPDTDTBTDI-8, DMO has the highest number average molecular weight (Mn = 17,400 g mol-1) among all polymers prepared. The PCPDTDTBTDI-8, DMO and PCPDTDTBTDI-8, 8 which have n-octyl substituents on their CPDT units have comparable optical band gaps (Eg ~ 1.3 eV), which are around 0.1 eV lower than PCPDTDTBTDI-EH, DMO analogues that have 2-ethylhexyl substituents on their CPDT units. The polymers have their HOMO levels between -5.10 and -5.22 eV with PCPDTDTBTDI-EH, DMO having the deepest highest occupied molecular orbital (HOMO) energy level. The lowest unoccupied molecular orbital (LUMO) levels of the polymers are between -3.4 and -3.5 eV. All polymers exhibit good thermal stability with decomposition temperatures surpassing 350 °C. Powder X-ray diffraction (XRD) studies have shown that all polymers have the amorphous nature in solid state.

Characteristics of Low Band Gap Copolymers Containing Anthracene-Benzothiadiazole Dicarboxylic Imide: Synthesis, Optical, Electrochemical, Thermal and Structural Studies.

Two novel low band gap donor-acceptor (D-A) copolymers, poly[9,10-bis(4-(dodecyloxy)phenyl)-2,6-anthracene-alt-5,5-(4',7'-bis(2-thienyl)-2',1',3'-benzothiadiazole-N-5,6-(3,7-dimethyloctyl)dicarboxylic imide)] (PPADTBTDI-DMO) and poly[9,10-bis(4-(dodecyloxy)phenyl)-2,6-anthracene-alt-5,5-(4',7'-bis(2-thienyl)-2',1',3'-benzothiadiazole-5,6-N-octyl-dicarboxylic imide)] (PPADTBTDI-8) were synthesized in the present work by copolymerising the bis-boronate ester of 9,10-phenylsubstituted anthracene flanked by thienyl groups as electron-donor units with benzothiadiazole dicarboxylic imide (BTDI) as electron-acceptor units. Both polymers were synthesized in good yields via Suzuki polymerisation. Two different solubilizing alkyl chains were anchored to the BTDI units in order to investigate the impact upon their solubilities, molecular weights, optical and electrochemical properties, structural properties and thermal stability of the resulting polymers. Both polymers have comparable molecular weights and have a low optical band gap (Eg) of 1.66 eV. The polymers have low-lying highest occupied molecular orbital (HOMO) levels of about -5.5 eV as well as the similar lowest unoccupied molecular orbital (LUMO) energy levels of -3.56 eV. Thermogravimetric analyses (TGA) of PPADTBTDI-DMO and PPADTBTDI-8 did not prove instability with decomposition temperatures at 354 and 313 °C, respectively. Powder X-ray diffraction (XRD) studies have shown that both polymers have an amorphous nature in the solid state, which could be used as electrolytes in optoelectronic devices.

On the use of atomistic simulations to aid bulk metallic glasses structural elucidation with solid-state NMR.

Solid-state nuclear magnetic resonance (ssNMR) experimental 27Al metallic shifts reported in the literature for bulk metallic glasses (BMGs) were revisited in the light of state-of-the-art atomistic simulations. In a consistent way, the Gauge-Including Projector Augmented-Wave (GIPAW) method was applied in conjunction with classical molecular dynamics (CMD). A series of Zr-Cu-Al alloys with low Al concentrations were selected as case study systems, for which realistic CMD derived structural models were used for a short- and medium-range order mining. That initial procedure allowed the detection of trends describing changes on the microstructure of the material upon Al alloying, which in turn were used to guide GIPAW calculations with a set of abstract systems in the context of ssNMR. With essential precision and accuracy, the ab initio simulations also yielded valuable trends from the electronic structure point of view, which enabled an overview of the bonding nature of Al-centered clusters as well as its influence on the experimental ssNMR outcomes. The approach described in this work might promote the use of ssNMR spectroscopy in research on glassy metals. Moreover, the results presented demonstrate the possibility to expand the applications of this technique, with deeper insight into nuclear interactions and less speculative assignments.

Thermally activated surface oxygen defects at the perimeter of Au/TiO2: a DFT+U study.

Density functional theory calculations were performed to examine the formation of oxygen atom vacancies on three model surfaces namely, clean anatase TiO2(001) and, Au3 and Au10 clusters supported on anatase TiO2(001). On the Au/TiO2 systems, three different types of lattice oxygen atoms can be identified: the Ti-O-Au bridge, the Ti-O-Ti bridge in the perimeter of the Au cluster and the Ti-O-Ti bridge away from the Au cluster, the oxygen atoms on the clean surface. The variation in ΔG° with temperature for surface O vacancy formation was calculated for these three situations using total-energy, vibrational structure and optimized geometries of the material surfaces and the O2 molecule. The calculations reveal that the O defect formation on the clean anatase TiO2(001) surface seems very difficult due to the large positive value of ΔG° (290 kJ mol(-1)) from 0 to 650 K. However, the presence of the Au cluster on the TiO2 surface changes the surface chemistry of the TiO2 significantly. We observed that the trend in ΔG° variation for the vacancy formation from the Ti-O-Au bridge is the same as on Au3/TiO2 and Au10/TiO2 systems, almost constant with large positive values of ΔG° around 250 and 350 kJ mol(-1), respectively. The ΔG° for the perimeter defect formation (Ti-O-Ti bridge in the perimeter of the Au cluster) is smaller for Aun/TiO2 systems than the clean TiO2 surface, however, the vacancy formation is possible only for the Au10/TiO2 system (close to 506 K). Finally, extended calculations for other oxygen atoms on the Au10/TiO2 model reveal that the trend in ΔG° variation is similar for all the interface or perimeter O atoms around the Au cluster with marginal differences in the numerical value of ΔG°. Since, the surface O atoms are activated only in the presence of a particular sized Au, we propose that a Au catalyzed Mars-van Krevelen mechanism could be a possible reaction mechanism for CO oxidation on Au/TiO2 catalysts at slightly elevated temperatures.

Theoretical study of the reaction between HF molecules and hydroxyl layers of Mg(OH)2.

The reaction of HF molecules with brucite, Mg(OH)(2), leading to the formation of Mg(OH)(2-x)F(x), was theoretically studied by ab initio density functional theory (DFT) with periodic boundary conditions. We proposed as mechanism for this reaction four elementary steps: adsorption of the HF molecule, OH(-) liberation from brucite as a water molecule, desorption of the newly formed H(2)O, and rearrangement of the F(-) anion into a hydroxyl position. For the Mg(OH)(2-x)F(x) formation, with x = 1/9, the final product, outcome from an initially adsorbed HF molecule, we computed the Helmholtz free energy variation DeltaF = -23 kcal/mol. The calculated frequency for the most intense infrared band, a Mg-F stretching mode, was 342 cm(-1). Two transition states, corresponding to the hydroxyl reacting with a proton forming a water molecule and migration of a fluoride anion into a hydroxyl vacancy, were computed. The calculated reaction barriers indicate that the reaction between Mg(OH)(2) layers and HF molecules is slow and irreversible.

Co-infecção tuberculose HIV/AIDS. Analise do momento do diagnostico e prognostico na era pre-HAART / Tuberculosis and HIV/AIDS co-infection. Time of Diagnosis analysis on pre HAART era

o A AIDS e uma sindrome que promove comprometimcento da imunidade celular do hospedeiro, podendo propiciar o surgimento da tuberculose (TB). No entanto, a co-infeccao TB/AIDS, tem apresentacao clinica, radiologica e laboratorial muito diferente daquelas encontradas nos individuos nao infectados pelo HIV. Este trabalho se propos a avaliar o momento do diagnostico no individuo com essa co-infeccao no periodo de dezembro de 1995 a maio de 1996 no Centro de Referencia e Treinamento-DST/AIDS (CRT-DST/AIDS) na cidade de Sao Paulo. As radiografias de torax foram analisadas por dois radiologistas foi chamado para opinar. Foram descritos dados epidemiologicos, radiologicos e laboratoriais de 150 pacientes com diagnostico de tuberculose endotoracica (TB-E) e infectados pelo HIV ou com AIDS. Destes pacientes, 121 (80,7 porcento) eram homens e 29 (19,3 porcento) mulheres. Para definicao de caso de AIDS foram utilizados Criterios Rio de janeiro/Caracas e CDC modificado, resultando em 141 (94 porcento) casos da co-infeccao TB/AIDS e 9(6 porcento) casos de TB em individuos infectados pelo HIV. Quanto a distribuicao da TB-E, 116 (77,3 porcento) dos pacientes apresentaram a forma pulmonar isolada, 11 (7,3 porcento) forma pulmonar e pleural, 10(6,7 porcento) forma pulmonar e ganglionar e 13 (8,7 porcento) apresentaram formas disseminadas. A idade variou de 20-62 anos. Foi possivel obter contagem de linfocitos CD4+ (CCd4) em 115 pacientes, e realizacao de teste tuberculinico (TT) em 91. Em 82 pacientes (71,3 porcento) a CCD4 estava abaixo de 50 cels/mm3. Cinquenta e sete pacientes (60,7 porcento) apresentaram TT nao reator (0,0 mm de enduracao). A analise radiologica mostrou 87 (58 porcento) laudos discordantes. Surpreendentemente, a radiografia de torax (RX-T) foi normal em 56 pacientes (37,3 porcento). O infiltrado reticular foi a das RX-T e adenomegalia hilar em 17 (11,3 porcento)

Co-infeccao Tuberculose HIV/AIDS. Analise do momento do diagnostico e prognostico na era pr‚-HAART

A AIDS e uma sindrome que promove comprometimento da imunidade celular do hospedeiro, podendo propiciar o surgimento da tuberculose(TB). No entanto, a co-infeccao TB/AIDS, tem apresentacao clinica, radiologica e laboratorial muito diferente daquelas encontradas nos individuos nao infectados pelo HIV. Este trabalho se propos a avaliar o momento do diagnostico no individuo com essa co-infeccao no periodo de dezembro de 1995 a maio de 1996 no Centro de Referencia e Treinamento-DST/AIDS (CRT-DST/AIDS) na cidade de Sao Paulo. As radiografias de torax foram analisadas por dois radiologistas diferentes sem que houvesse comunicacao entre eles; quando ocorreram laudos discordantes um terceiro radiologista foi chamado para opinar

Determinants of patient satisfaction in a large, municipal ED: the role of demographic variables, visit characteristics, and patient perceptions.

We investigated predictors of patient satisfaction in a large, municipal emergency department (ED). Patients were telephoned 10 days postvisit, and satisfaction was assessed using a structured survey with 22 items measuring several domains, as well as the estimated length of stay. The dependent variables consisted of ratings of overall satisfaction and likelihood of recommending the ED to others. Data were obtained from 437 (38.7%) patients. Univariate statistics revealed strong relations between indicators of perceived care and both dependent variables, with weaker and mixed findings pertaining to demographics and visit characteristics. The final logistic regression predicting overall satisfaction included the following items (P < .05): degree to which staff cared for the patient as a person, perceptions of safety, understandability of discharge instructions, nurse's technical skills, and satisfaction with wait for physician. Likelihood to recommend was associated with (P < .05): degree to which staff cared for the patient as a person, understandability of discharge instructions, perceptions of safety, age, and insurance status. Patients' perceptions of care, rather than demographics and visit characteristics, most consistently predicted satisfaction. However, differences were observed between the specific predictors for overall satisfaction and likelihood to recommend, providing a possible explanation for inconsistencies observed in the literature.

Emergency department personnel accuracy at estimating patient satisfaction.

We investigated the congruence between emergency department (ED) personnel estimations of patient satisfaction and actual patient satisfaction. Actual patient satisfaction was assessed via telephone interview. Before the findings were disseminated, ED personnel were asked to "predict" the results by estimating the average rating they believed patients gave for each of the 22 indicators. Surveys were obtained from 478 of 1,139 (42.1%) patients and 59 of 76 (77.6%) ED personnel. ED personnel consistently estimated average satisfaction scores to be significantly lower than what patients actually reported across 19 of the 22 indicators. ED personnel grossly overestimated average patient length of stay (LOS) (5.7 h vs. 3.5 h actual). Results suggest that ED personnel consistently estimated patients to be less satisfied than they actually were across multiple domains. Moreover, ED personnel estimated average LOS to be more than 2 h longer than patients' actual LOS. Hypotheses for why this bias occurred are discussed.

Telephone contact of patients visiting a large, municipal emergency department: can we rely on numbers given during routine registration?

We sought to determine whether we could successfully contact patients for follow-up using telephone numbers given during routine emergency department (ED) registration. Every fifth patient visiting our ED during the study period was eligible. Three calls were made to each number. Calls began 7 days after the ED visit. Of 1,136 patients, we successfully contacted 478 (42.1%). Of those patients unreachable across all three attempts, 183 (16.1%) had given wrong numbers, 133 (11.7%) had disconnected lines, and 156 (13.7%) had three consecutive "no answers." Females and patients with nonurgent complaints were significantly more likely to be contacted. Despite stringent calling protocols, we successfully contacted only 42% of our patients. Nearly 28% gave wrong or disconnected numbers. Placing two additional calls to those patients who were not home or did not answer initially nearly doubled the overall contact rate, although similar efforts for patients who initially gave wrong or disconnected numbers yielded no appreciable gains. Females and nonurgent patients were over-represented.

The increasing burden of pediatric firearm injuries on the emergency department.

INTRODUCTION: Surveillance of injuries is necessary in order to develop preventive strategies. The purpose of this study was to examine pediatric gunshot wounds over a seven-year period for changes in frequency, site of injury, and demographic variables. METHODS: The medical charts of all pediatric patients (age < 19 years) who presented to the two urban emergency departments (EDs) in Baton Rouge, Louisiana between January 1, 1987, and December 31, 1993, were retrospectively reviewed. Data included age, date and time of presentation, site(s) of injury, disposition, operative procedure, and hospital stay. Results were stratified into age < 1 year, 1-4 years, 5-9 years, 10-14 years, and 15-19 years. RESULTS: During the study period there were 465 pediatric firearm injuries seen in the two urban EDs. Of all patients, 302 (65%) were male, and the proportion remained unchanged during the study period. The incidence of firearm injury rose from 3.0/1000 pediatric ED patients in 1987 and 5.9 in 1993 (P < 0.05). Mean age rose from 12.2 +/- 2.1 years to 15.1 +/- 1.6 years (P < 0.05), and admission percentage rose from 7 to 46% (P < 0.05) between 1987 and 1993. The proportion of firearm injuries in the age group 15 to 19 years rose from 52% in 1987 and 82% in 1993 (P < 0.05). Operative procedures were required by 56 (12%) and intensive care admission by nine (2%); this did not change significantly over the study period. Thirty-three (7%) of all victims died. The most common sites of injury in decreasing order of frequency were extremity (60%), head/neck (14%), chest/back (13%), abdomen/flank (7%), and pelvis/buttocks (6%); they did not vary by age group. A significantly greater proportion of pediatric firearm injuries presented between 5 PM and 5 AM (65%), on Friday (24%) or Sunday (20%), and during the three summer months (29%) or December (11%). CONCLUSIONS: The frequency of pediatric gunshot wounds presenting to urban EDs has increased significantly since 1987. These findings confirm previous studies concerning site of injury as well as time, date, and month of presentation and suggest targeting preventative measures at the 15- to 19-year age group.