bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Bypass Fat and Bypass Protein Supplementation During Transition Period on Reproductive Performance of Assam Hill Goat
Authors: Hegde Akshay Krishnamurti , Keshav  , Borah Pranjal
Published: January 2024

The present study was undertaken to evaluate the response of Assam Hill Goat (AHG) in terms of their productive and reproductive performances upon bypass fat and bypass protein supplementation during the transition period. Twenty-four AHG in transition period (21day prepartum to 21day post-partum) were divided into two equal groups (n=12) viz. T-0 and T-1; where Group T-1 was supplemented with 10 g of bypass fat and 5 g of bypass protein along with their normal diet for a period of 42 days. Group T-0 acted as control and was provided with a normal diet without any supplementation. Blood samples were collected on day -21, -14, -7, 0 (day of kidding), +7, +14 and +21 of the transition period for haemato-biochemical studies. Birth weight, milk yield and time taken for expulsion of foetus and foetal membrane and incidences of peri-partum diseases were recorded. The results indicated that, the supplementation had no significant effect on haematological parameters (TLC, Neutrophil count and Hb), serum Ca, P, glucose, globulin and GGT activity. Serum non-esterified fatty acids (NEFA) levels were significantly (p<0.05) lower in supplemented groups on the day of kidding (0.75±0.09 mmol/L) and day 21 of postpartum (0.38±0.04 mmol/L). Significantly (p<0.05) higher mean values of total protein on day -14, -7, 0, 7, 14 and 21 (6.96±0.21, 6.99±0.25, 7.02±0.26, 7.24±0.28, 7.03±0.12 and 6.95±0.15 g/dL) and serum albumin values on day -14, 7 and 21 (4.46±0.23, 4.69±0.23 and 4.44±0.27 g/dL) were recorded in T-1 group. Significantly (p<0.05) lower mean values of BUN were recorded in T-1 group on day 0, 7 and 21 (30.25±1.74, 35.62±1.58 and 42.08±1.45 mg/dL). The supplemented (T–1) group recorded significantly higher milk yield (303.5±21.16, 306.25±19.67 and 310.75±23.93 ml) on day 14, 21 and 28 after kidding and there was a significant (p<0.05) reduction in time taken for the expulsion of foetus (89.75±11.84 mins) and foetal membranes (90.50±5.86 mins). The supplementation of bypass fat (10g/day) and bypass protein (5 g/day) during the transition period reduce the effect of negative energy balance and facilitate quicker recovery from negative energy balance along with improvement in milk yield and reduce time taken for expulsion of foetus and foetal membrane.
Evaluation of Zepp’s Procedure in Management of Chronic Otitis Externa in Dogs
Authors: Sharma Mohan Lal , Tanwar Mahendra , Jhirwal S. K.
Published: January 2024

The study was conducted on 10 dogs presented at VCC, VSR, CVAS Bikaner with the owner complaint of consistent shaking of head and scratching of ear, rubbing of ear to hard object, purulent foul smelling discharge from ear and also had history of long medicinal treatment using NSAIDS, steroids and antibiotics. Clinical otoscopic examination of the ears revealed purulent odoriferous discharge, with stenosis and calcification of lateral ear canal in some cases. For definitive diagnosis ear exudate was collected in sterile swabs inserted in lateral ear canal using otoscope, and it was evaluated for parasites, bacteria, fungi, yeast. Skull radiography was performed to evaluate calcification in the ear canal and involvement of middle ear. After thorough examination it was concluded that the animals were suffered from chronic otitis externa and decided to perform zepps procedure (lateral ear canal resection) to increase drainage, facilitate ventilation of ear canal and easy placement of topical agents into horizontal ear canal. Zepp’s procedure was performed under general anaesthesia; post-operative care was done using regular application of topical steroids, nonsteroidal anti-inflammatory drugs and antibiotics along with systemic antibiotics. After one month of post-operative care four ear showed excellent healing and dryness of the ear, Infection subsided in three ears and no improvement was seen in three ears. Microbiology suggested mixed bacterial infection in 6 dogs. Zepp’s procedure is a conservative surgical operation found to be a choice of surgical management in cases of early stages of otitis externa which has not been progressed to otitis media.
Does Monetary Policy Influence Non-performing Loans of Listed Commercial Banks in Kenya?
Authors: Koskei Loice , Samoei Daniel
Published: January 2024

The Kenya banking sector plays a crucial role in Kenya’s economy despite the prevailing macroeconomic headwinds in the Country. The Banking Sector Industry Report of 2023 indicated that the banking sector contributed to 66% of gross domestic product as of December 2022. The high levels of non-performing loans remain a concern in the Kenya banking sector. The study sought to assess the influence of monetary policy on non-performing loans in the banking sector in Kenya. The target population is all listed commercial banks in Kenya. Using monthly secondary data from November 2019 to September 2023 obtained from the Central Bank of Kenya, the study utilized a multiple regression model to estimate the influence of monetary policy on the percentage growth of nonperforming loans of listed commercial banks in Kenya. Findings pointed out that Repo rates and Treasury bill rates do not influence non-performing loans of listed commercial banks in Kenya as measured by the gross non-performing loans ratio as exhibited by the P-values of 0.327866 and 0.577173 respectively, which is greater than 0.05. The results also implied that the central bank rate and interbank rates do influence non-performing loans of listed commercial banks in Kenya as measured by the gross non-performing loans ratio as illustrated by the P-values of 0.028844 and 0.00018 respectively, which is less than 0.05. According to the findings, the study recommends that policymakers should prioritize creating a strong financial ecosystem so that monetary policy can be utilized to regulate commercial bank interest rates. This will, in effect, serve to decrease the expansion of non-performing loans, reduce risk and entice competitors into the financial sector, enhance the capital base, increase lending to promote feasible projects, and, as a result, stimulate the country's growth.
Sustainability of Livelihood of Tribal Society in Rural Odisha Through Upskilling the Youth Mass: An Empirical Study
Authors: Das Kishore Kumar
Published: January 2024

Aims: The current study's objective is to examine the characteristics of skills of tribal young people living in rural areas of Odisha & suggest the skill programme which can develop their sustainable livelihood.

Sample: The present study focusses on the rural tribal youths of Keonjhar district of Odisha. The study's target population includes young people who were between the ages of 15 and 29. There were 270 responders in the sample, with 55.7 percent men and 46.3 percent women.

Study Design: This is a concurrent study that has used a mix of qualitative and quantitative methods. The survey was conducted using a Likert Scale questionnaire. Finally, SPSS was used to process the data and present a descriptive view of the results with figure, table and chart.

Place and Duration of Study:  The place of the study consists of Odisha’s rural district Keonjhar and the data were collected during the 2nd half of 2023.

Results: The preceding study that demonstrated that skill development for rural youth can promote sustainable livelihood in Odisha supported how young people saw the training in skill development.

Conclusion: The report concluded that state youth policies be implemented in spirit, including agricultural-based skill training; that the federal government and the state make greater investments in programs like "start-up" schemes for scheduled caste and scheduled tribe in isolated rural areas; and that the government take responsibility for the market.
Demographical Factors and Their Hindrances to Metropolitan Land Zone Use Policy Adherances
Authors: Mogire Dennis Annan , Kweyu Raphael , Francis Jane Kagendo
Published: January 2024

The appropriate application of metropolitan land zone use policies and regulations may help in resolving metropolitan land zone use hitches such as undesirable zonal fragmentation, zonal use mix-up and zonal encroachment. This research aims at contributing to acquaintance required to enhance adherence to metropolitan land zone uses in metropolitan land zone use planning. This paper focused on the hindrances to metropolitan land zone use adherence in Nakuru City. Human population in Nakuru city has been on upward trajectory over the past thirty years. Just like any other modern metropolitan area in the world, Nakuru city’s land use is mainly divided into residential, industrial, commercial and agricultural zone. The size of Nakuru city (municipality) has remained unchanged since 1974. However, there is a proposal to expand its size following its upgrading into a city. This has pressurized the already limited metropolitan land use zones. The study adopted Hoyt Theory which says that metropolitan land use zones are swayed by financial factors. Precisely, the study’s main objective was to assess socio-economic aspects of metropolitan demography as hindrances to metropolitan land zone use adherence. This paper employed descriptive survey design. Field data from a sample size of 400 respondents from eleven sample units were collected. All demographical factors (ignorance, political interference, nature of implementation, corruption, availability of capital, and population influx) under study had positively correlated with metropolitan land zone use policy adherences since they had a correlation coefficient of 0.82, 0.90, 1.00, 0.80, 0.92 and 0.98 respectively. The average t-test of all demographical factors under investigation was 0.02. Therefore, the null hypothesis was rejected at p-value of 0.05. Information from Key informants were also incorporated. This research suggested that these hindrances should be minimized through incorporation of all stakeholders, integrity, checked urbanization and proper implementation and adherence to all metropolitan land zone use policies that are in place. This study may be useful to metropolitan land planners, developers and government.
Choosing Confidence Intervals in Bioequivalence Studies: 100(1 - 2\(\alpha\) )% and 100(1 - \(\alpha\) )% Approaches
Authors: Li Kexuan , Sinks Susie , Sun Peng , Yang Lingli
Published: January 2024

A bioequivalence study is a type of clinical trial designed to compare the biological equivalence of two different formulations of a drug. Such studies are typically conducted in controlled clinical settings with human subjects, who are randomly assigned to receive two formulations. The two formulations are then compared with respect to their pharmacokinetic profiles, which encompass the absorption, distribution, metabolism, and elimination of the drug. Under the guidance from Food and Drug Administration (FDA), for a size-\(\alpha\) bioequivalence test, the standard approach is to construct a 100(1 - 2\(\alpha\))% confidence interval and verify if the confidence interval falls with the critical region. In this work, we clarify that 100(1-2\(\alpha\))% confidence interval approach for bioequivalence testing yields a size-\(\alpha\) test only when the two one-sided tests in TOST are "equal-tailed". Furthermore, a 100(1 - \(\alpha\))% confidence interval approach is also discussed in the bioequivalence study.
Interference Mitigation and Power Consumption Reduction for Cell Edge users in Future Generation Networks
Authors: Uloh Christopher O. , Ubom Emmanuel A. , Obot Akaniyene U. , Ukommi Ubong S.
Published: January 2024

In 5G heterogeneous networks (HetNets), a unique and promising option to address the growing demand for higher data rates is network densification of small cells (SCs) and macro cells (MCs). Unfortunately, the 5G HetNets are suffering severe issues due to the interference caused by these densely populated SCs and their high-power consumption. To lessen interference and boost network throughput, a New Soft Frequency Reuse (NSFR) technique is put forth in this work. The proposed scheme uses the Soft Frequency Reuse (SFR) for on/off switching of the SCs according to their Interference Contribution Rate (ICR) values. By splitting the cell region into edge and center zones, it resolves the interference issue caused by the densely packed SCs. Moreover, SC on/off switching addresses the issue of excessive power consumption and improves the 5G network's power efficiency. Furthermore, this work tackles the irregular shape nature problem of 5G HetNets and compares two different proposed shapes for the centre zone of the SC, existing irregular and proposed circular shapes. Additionally, the optimum radius of the centre zone, which maximizes the total system data rate, is obtained. A comparative analysis of power consumption, data rate and power efficiency was performed between the NSFR model, the SFR model and the proposed model. The results show that for 1000 number of equipment, the proposed model has a low power consumption of 1.72KW compared to 3.51KW for SFR and 3.73KW for NSFR. Data rate of 12.19kbps compared to 11.42kbps for SFR and 11.09kbps for NSFR. Also, power efficiency of 610kbps/W compared to 572kbps/W for SFR and 560kbps/W for NSFR. These results imply that the interference mitigation handled by the proposed scheme improves by approximately 22%.
Characteristics of D-Dimer Levels in Patients Confirmed Positive for COVID-19 Aged 45 – 70 Years at UKI Hospital for the Period December 2020 – September 2021
Authors: Luhulima Danny Ernest Jonas , Saluntondok Welly , Irwan Nafisah Erica Maulidiani
Published: January 2024

COVID-19 is a disease caused by the SARS-CoV-2 virus. COVID-19 is divided into several clinical symptoms based on a person's experiences. In severe clinical signs of COVID-19, D –Dimer will be significantly higher. This study aims to determine D-Dimer levels in COVID-19 patients aged 45 – 70 and uses a descriptive-analytic method with a retrospective cross-sectional design. The number of samples was 198 patients whose D-Dimer levels were checked and 127 patients who received anticoagulant prophylaxis. The research samples were all medical records of patients suffering from COVID-19 aged 45 - 70 years and who had checked D-Dimer levels at RSU UKI from December 2020 to September 2021 found that 145 patients (73.2%) had normal D-Dimer levels, 53 patients (26.8%) had increased D-Dimer levels. The distribution of women were 100 patients (50.5%), and men were 98 patients (49.5%), the highest range was aged 54 - 62 years with 74 patients (37.4%), clinical symptoms were being experienced by 122 patients (61.6%), and comorbid hypertension was the most common disease with 64 patients (32.3%). A significant relationship was found between D-Dimer levels and comorbidities (p=0.04). Anticoagulant prophylaxis was given to 127 patients, with mild symptoms experienced by five patients (3.6%), moderate symptoms experienced by 73 patients (57.5%), and severe symptoms experienced by 49 patients (38.6%). However, no significant relationship was found (p=0.66) between administering anticoagulant prophylaxis and D-Dimer levels in patients with mild, moderate, or severe symptoms.
Nutrition composition and anthocyanin content of mulberry fruits (Morus alba L.) by different ripening stage grown in the south of Thailand, applicants in sorbet and sherbet ice-cream and analysis of physical, chemical and sensory evaluation
Authors: Sangteerakij Duangkamon , Rodyu Sauwanee , Junden Sirisopa
Published: January 2024

This experiment was study on properties of each ripening stage of mulberry fruits and conducted study of physical and chemical properties of mulberry fruit at each ripening stage and apply mulberry fruit in ice cream products. Mulberry at fully-ripened stage showed higher phenolic, flavonoid and anthocyanin content. Mulberry fruits were used to make four different types of ice cream; sorbet, sherbet, milk, and yogurt. The sensory qualities of mulberry ice cream were studied (9-point hedonic scale), and the results revealed that mulberry sherbet ice cream had the highest overall acceptability, followed by mulberry sorbet ice cream. The physical, chemical, nutrition composition, and microbiological properties of mulberry sherbet and sorbet ice cream were investigated further. Due to the presence of fresh milk in the composition, sherbet ice cream has a higher overrun and lightness (L*) than sorbet ice cream. The mulberry sherbet ice cream had more incredible energy, energy from fat, total fat, saturated fat, cholesterol, protein, total carbohydrates, calcium, dietary fiber and phenolic compounds. This study shows that mulberry has beneficial properties in terms of consumer acceptance and

health benefits, particularly in mulberry sherbet ice cream. All mulberry ice creams had been sanitized and were suitable to consume. As a result, mulberry ice cream formulations can add value to agricultural products and suggested for commercialization.
Effects of copolyester/polycarbonate blend composition on the thermal diffusivity of dye transfer printing
Authors: Miyata Tadakazu , Inaki Kanako , Morikawa Junko , Satoto Rahmat , Hashimoto Toshimasa
Published: February 2004

The effect of the blend composition on the thermal diffusivity for blends of a poly(ethylene‐co‐cyclohexane 1,4‐dimethanol terephthalate) (PETG) and a bisphenol‐A polycarbonate (PC) that have been used as base films for a thermal dye transfer (TDT) printing system was examined. The inflection point in the thermal diffusivity measured by temperature wave analysis almost matched the inflection point of storage modulus measured by dynamic mechanical analysis. This result implied that the temperature dependence of thermal diffusivity related to the change in the microstructure of the PETG/PC blend. Furthermore, the correlation between the printing sensitivity and the thermal diffusivity at the actual thermal head temperature of TDT printing was found. The thermal diffusivity increased with increasing PC content, while the printing sensitivity decreased. The PETG/PC blend film suitable for the TDT printing base film could be obtained by adjusting the PC content in the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 72–76, 2004
Creep–recovery experimental investigation of crude oil–polymer emulsions
Authors: Ghannam Mamdouh T.
Published: February 2004

Viscoelastic behavior of crude oil–Alcoflood polymer emulsions in terms of creep and recovery is extensively investigated using RheoStress RS100. Three different types of Alcoflood polymers in the concentration range of 100–104 ppm are covered. North sea crude oil with a concentration range of 10–75% by volume is employed for emulsion preparation. All viscoelastic tests of crude oil–polymer emulsions are carried out under 0.1 Pa of shear stress to make sure that the investigated behavior lies within the linear viscoelastic range. The viscoelastic behavior of crude oil–polymer emulsion is strongly influenced by crude oil concentration, Alcoflood concentration, and Alcoflood type. The viscoelastic behavior of crude oil–Alcoflood polymer emulsions can be simulated using the Maxwell model or the Burger model depending upon the polymer concentration. The Maxwell model can be used over the polymer concentration range of 0–5000 ppm, whereas the Burger model covers the higher polymer concentration range. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 226–237, 2004
Hydrophobically modified acrylamide‐based polybetaines. I. Synthesis, characterization, and stimuli‐responsive solution behavior
Authors: Johnson Kathryn M. , Fevola Michael J. , McCormick Charles L.
Published: February 2004

Acrylamide‐based, hydrophobically modified (HM) polybetaines containing N‐butylphenylacrylamide (BPAM) and varying amounts of the sulfobetaine monomer 3‐(2‐acrylamido‐2‐methylpropanedimethylammonio)‐1‐propanesulfonate (AMPDAPS) or the carboxybetaine monomer 4‐(2‐acrylamido‐2‐methylpropyldimethylammonio)butanoate (AMPDAB) were synthesized by micellar copolymerization. The corresponding control (co)polymers lacking BPAM or betaine comonomers were also prepared. The terpolymers were characterized by 13C‐NMR and UV spectroscopy, classical light scattering, and potentiometric titration. Low charge density polymers contained 3.9–8.6 mol % betaine, whereas the high charge density systems contained 17–25 mol % betaine; the HM polymers contained up to 1.0 mol % BPAM as the hydrophobe. The weight‐average molecular weights of the polymers ranged from 4.19 × 105 to 1.29 × 106 g/mol, and most HM polymers exhibited negative second virial coefficients. The pKa of the carboxybetaine moieties was found to increase with increasing levels of hydrophobic and betaine comonomer incorporation. The response of aqueous polymer solutions to various external stimuli, including changes in solution pH and electrolyte concentration, was investigated using rheological analysis. The solution behavior of the polymers was characteristic of HM polyacrylamides and acrylamide‐based polyzwitterions. The high charge density HM polycarboxybetaine exhibited unusual solution behavior that can be explained in terms of electrostatic, hydrophobic, and hydrogen‐bonding associations. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 647–657, 2004
Wood bonding by mechanically‐induced in situ welding of polymeric structural wood constituents
Authors: Gfeller B. , Properzi M. , Zanetti M. , Pizzi A. , Pichelin F. , Lehmann M. , Delmotte L.
Published: February 2004

Mechanically induced wood fusion welding, without any adhesive, is shown here to yield rapidly bonding wood joints satisfying the relevant requirements for structural application. The mechanism of mechanically induced vibrational wood fusion welding is shown to be due mostly to the melting and flowing of amorphous cells–interconnecting polymer material in the structure of wood, mainly lignin, but also some hemicelluloses. This causes a partial detachment, the “ungluing,” of long wood cells and wood fibers and the formation of an entanglement network drowned in a matrix of melted material which then solidifies, thus forming a wood cell/fiber entanglement network composite with a molten lignin polymer matrix. During the welding period some of the detached wood fibers which are no longer being held by the interconnecting material are pushed out of the joint as excess fiber. Crosslinking chemical reactions of lignin and carbohydrate‐derived furfural also occur. Their presence has been identified by CP‐MAS 13C‐NMR. These reactions, however, are relatively minor contributors during the very short welding period. Their contribution increases after welding has finished, which explains why relatively longer holding times under pressure after the end of welding contribute strongly to obtaining a good bond. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 243–251, 2004
Melt rheology and morphology of uncompatibilized and in situ compatibilized nylon‐6/ethylene propylene rubber blends
Authors: Oommen Zachariah , Zachariah Sisy R. , Thomas Sabu , Groeninckx Gabriel , Moldenaers Paula , Mewis Jan
Published: February 2004

Melt rheology and morphology of nylon‐6/ethylene propylene rubber (EPR) blends were studied as a function of composition, temperature, and compatibilizer loading. Uncompatibilized blends with higher nylon‐6 content (N90 and N95) and rubber content (N5 and N10) had viscosities approximately intermediate between those of the component polymers. A very clear negative deviation was observed in the viscosity–composition curve over the entire shear rate range studied for blends having composition N30, N50, and N70. This was associated with the interlayer slip resulting from the high‐level incompatibility between the component polymers. The lack of compatibility was confirmed by fracture surface morphology, given that the dispersed domains showed no sign of adhesion to the matrix. The phase morphology studies indicated that EPR was dispersed as spherical inclusions in the nylon matrix up to 30 wt % of its concentration. A cocontinuous morphology was observed between 30 and 50 wt % nylon and a phase inversion beyond 70 wt % nylon. Various models based on viscosity ratios were used to predict the region of phase inversion. Experiments were also carried out on in situ compatibilization using maleic anhydride–modified EPR (EPR‐g‐MA). In this reactive compatibilization strategy, the maleic anhydride groups of modified EPR reacted with the amino end groups of nylon. This reaction produced a graft copolymer at the blend interface, which in fact acted as the compatibilizer. The viscosity of the blend was found to increase when a few percent of modified EPR was added; at higher concentrations the viscosity leveled off, indicating a high level of interaction at the interface. Morphological investigations indicated that the size of the dispersed phase initially decreased when a few percent of the graft copolymer was added followed by a clear leveling off at higher concentration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 252–264, 2004
Blends of ultrasonically devulcanized and virgin carbon black filled ethylene–propylene–diene monomer rubbers
Authors: Yun Jushik , Isayev A. I.
Published: February 2004

Ultrasonically devulcanized ethylene–propylene–diene monomer (dEPDM) rubber was blended with virgin ethylene–propylene–diene monomer (vEPDM) rubber. The properties of these blends were investigated and compared with those of blends of ground ethylene–propylene–diene monomer (gEPDM) and vEPDM. The dynamic properties and curing characteristics were studied. The dynamic properties of the uncured blends showed that the gEPDM/vEPDM compounds were more elastic than the dEPDM/vEPDM compounds at a low frequency range, whereas the opposite trend was observed at a high frequency range. In contrast, the dynamic properties of gEPDM/vEPDM vulcanizates were less elastic than those of dEPDM/vEPDM vulcanizates at a low frequency range. The curing characteristics of the blends indicated that an increase in the dEPDM content in the dEPDM/vEPDM blends reduced the scorch time and the maximum torque and increased the minimum torque. A similar but more pronounced tendency was also found for the gEPDM/vEPDM blends. The tensile properties of the dEPDM/vEPDM vulcanizates were much better than those of the gEPDM/vEPDM vulcanizates, indicating the significant benefit of ultrasonic devulcanization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 132–138, 2004
Reaction study of water‐borne polyurethanes based on isophorone diisocyanate, dimethylol propionic acid, and poly(hexane neopentyl adipate glycol)
Authors: Zhang Shubiao , Miao Wei , Zhou Yu
Published: February 2004

The reaction of isophorone diisocyanate (IPDI) with poly(hexane neopentyl adipate glycol) (HNA) and dimethylol propionic acid (DMPA) was researched through an analysis of the contents of the NCO groups of the prepolymers through which water‐borne polyurethanes (PUs) could be formed. The reaction activity of DMPA with IPDI was studied and compared to that of HNA on the basis of an investigation into the effects of the temperature and catalyst on the prepolymerization and the viscosity of the prepolymers. The results showed that the reaction of IPDI with DMPA was much slower than the reaction of HNA, and so DMPA was concluded to be a relatively inert nucleophilic reagent for attacking IPDI. A temperature of 80°C was suitable, with dibutyl tin dilaurate as a catalyst, for producing prepolymers from IPDI and mixtures of HNA and DMPA, whereas 60°C without catalysis was enough to complete the reaction of IPDI with HNA. This study may be helpful in understanding the prepolymerization of water‐borne PUs and in manufacturing them. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 161–164, 2004
Doping level change of polyaniline film during its electrochemical growth process
Authors: Liu Chen , Zhang Jiaxin , Shi Gaoquan , Chen Feng'en
Published: February 2004

Polyaniline (PANI) films doped with hydrochloric acid have been electrochemically deposited on mirrorlike platinum electrode surfaces by a cyclic voltammogram method. The Raman spectra of doped PANI films were investigated by excitation with a 633‐ or 785‐nm laser beam. It was found that the overall features of the Raman spectra depend strongly on the film thickness, due mainly to that the doping level of PANI film increases during the film‐growth process. X‐ray photoelectron spectroscopic (XPS) analysis and ultraviolet (UV)‐visible absorption spectrum results also confirmed this finding. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 171–177, 2004
Effects of glycerol and PE‐g‐MA on morphology, thermal and tensile properties of LDPE and rice starch blends
Authors: Wang Y.‐J. , Liu W. , Sun Z.
Published: February 2004

The effects of glycerol and polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the morphology, thermal properties, and tensile properties of low‐density polyethylene (LDPE) and rice starch blends were studied by scanning electron microscopy (SEM), differential scanning calorimetry, and the Instron Universal Testing Machine, respectively. Blends of LDPE/rice starch, LDPE/rice starch/glycerol, and LDPE/rice starch/glycerol/PE‐g‐MA with different starch contents were prepared by using a laboratory scale twin‐screw extruder. The distribution of rice starch in LDPE matrix became homogenous after the addition of glycerol. The interfacial adhesion between rice starch and LDPE was improved by the addition of PE‐g‐MA as demonstrated by SEM. The crystallization temperatures of LDPE/rice starch/glycerol blends and LDPE/rice starch/glycerol/PE‐g‐MA blends were similar to that of pure LDPE but higher than that of LDPE/rice starch blends. Both the tensile strength and the elongation at break followed the order of rice starch/LDPE/glycerol/PE‐g‐MA blends > rice starch/LDPE/glycerol > LDPE/rice starch blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 344–350, 2004
Crystallization behavior of starch‐filled polypropylene
Authors: Liu Wanjun , Wang Ya‐Jane , Sun Zhenhua
Published: February 2004

Starches of different granule sizes, including corn, rice, and amaranth starches, were used to prepare starch‐filled polypropylene (PP) and the effect of starch granule size on crystallization behavior PP was investigated. Differential scanning calorimetry and scanning electron microscopy were used to monitor the energy changes of the crystallization of the melt and to characterize the morphology of PP/starch composites, respectively. Little interaction was observed between starch and PP despite the difference in starch granule size. The crystallization temperature of PP decreased with the addition of starch and this decrease became more apparent with increasing starch granule size. During nonisothermal crystallization, the dependency of the relative degree of crystallinity on time was described by the Avrami equation. The addition of starch decreased the overall crystallization rate of PP, which was attributed to an increase in the activation energy of crystallization under nonisothermal conditions according to the Kissinger equation. An increase in starch granule size of starch would increase the crystallization activation energy of PP and consequently decrease its crystallization rate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 484–492, 2004
Kinetics of water absorption and hygrothermal aging rubber toughened poly(butylene terephthalate) with and without short glass fiber reinforcement
Authors: Yow B. N. , Ishiaku U. S. , Ishak Z. A. Mohd , Karger‐Kocsis J.
Published: February 2004

The objectives of this paper were to investigate the water absorption and hygrothermal aging behavior of rubber‐toughened poly(butylenes terephthalate) (RT‐PBT) with and without short glass fiber (SGF) reinforcement. The rubbers used in the study were AX8900 and EXL2314, both of which are acrylate‐based terpolymer. The effect of the hygrothermal aging on its fracture properties was also studied. The kinetics of the water absorption study were carried out on the injection‐molded samples of the RT‐PBTs and the SGF‐reinforced rubber‐toughened PBT (SGF‐RT‐PBT) at three immersion temperatures, 30, 60 and 90°C, for a total of 450 h. The study of the deterioration caused by the hygrothermal aging was conducted by investigating the fracture parameters and flexural properties of all the materials as both hygrothermally aged (HA) and redried state (RD). The modes of the failure of HA and RD samples were studied using the scanning electron microscopy (SEM) technique. It was found that all the samples conformed to Fickian behavior and the kinetics of absorption exhibited a strong dependency on the rubber types, presence of SGF, as well as the immersion temperature. Generally, SGF‐RT‐PBT showed a better resistance to hygrothermal aging than that of RT‐PBT and PBT, though a declining trend was observed in the fracture parameters, Kc and Gc. However, an opposite observation was exhibited in the flexural properties in some, but not all cases. Finally, the results obtained from SEM micrographs showed that permanent damage occurred in the materials and the hygrothermal aging had suppressed the plastic deformation ability of the PBT matrix and both types of impact modifiers where brittle failure was observed. Fiber pull‐out was apparently the failure mode of the SGF‐reinforced materials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 506–516, 2004
A visco‐hyperelastic constitutive model to characterize both tensile and compressive behavior of rubber
Authors: Shim V. P. W. , Yang L. M. , Lim C. T. , Law P. H.
Published: February 2004

The strain rate–dependent finite deformation behavior of three types of rubber under tension and compression are experimentally characterized using a Hopkinson bar. Based on the measured data, a frame‐independent incompressible visco‐hyperelastic constitutive equation is proposed to describe the tensile and compressive responses of rubber under high strain rates. The equation comprises two parts: a three‐parameter component based on an elastic strain energy potential, to characterize static hyperelastic behavior, and another with four parameters, developed from the BKZ model, to define rate sensitivity and strain history dependence. Established static and dynamic experimental techniques are employed to determine the seven parameters in the constitutive relationship. Comparison of predictions based on the proposed model with experiments shows that it is able to describe the visco‐hyperelastic behavior of rubber‐like materials under high strain rates. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 523–531, 2004
PVC/montmorillonite nanocomposites based on a thermally stable, rigid‐rod aromatic amine modifier
Authors: Liang Zhu‐Mei , Wan Chao‐Ying , Zhang Yong , Wei Ping , Yin Jie
Published: February 2004

Two kinds of polyvinyl chloride (PVC)/montmorillonite (MMT) nanocomposites were prepared by the melt intercalation method based on a thermally stable, rigid‐rod aromatic amine modifier and a commonly used 1‐hexadecylamine. The information on morphological structure of PVC/MMT nanocomposites was obtained using XRD and TEM. The mechanical, thermal, and flame retardant properties of the nanocomposites were characterized by universal tester, DMA, TGA, and cone calorimeter. The degree of degradation of PVC was studied by 1H‐NMR. MMT treated by the aromatic amine exhibited better dispersibility than that treated by 1‐hexadecylamine. The nanocomposites, based on this MMT, consequently exhibited better mechanical, thermal, and flame retardant properties and lower degradation degree than those based on 1‐hexadecylamine‐treated MMT. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 567–575, 2004
Preparation of asymmetric PEEKWC flat membranes with different microstructures by wet phase inversion
Authors: Buonomenna M. G. , Figoli A. , Jansen J. C. , Drioli E.
Published: February 2004

Membranes with controlled morphology were prepared by wet phase inversion from PEEKWC, a modified polyetheretherketone. Different membrane structures were obtained by using different nonsolvent/solvent pairs. The influence of several parameters, such as the composition of the polymer solution (concentration, type of solvent), the composition of the coagulation bath, and the exposure time before immersion in the coagulation bath, on the membrane morphology was studied. The PEEKWC/solvent/nonsolvent phase diagrams, with various solvent/nonsolvent combinations, were determined and correlated to the process of phase separation during membrane formation. Using solvent/nonsolvent pairs with a high mutual affinity (DMF/water, DMA/water), porous membranes for possible application in microfiltration were obtained. The THF/water combination allowed the formation of asymmetric membranes with a dense skin layer, suitable for gas separation applications. Nitrogen permeance of all porous membranes was measured as function of pressure. Application of the Dusty Gas model permitted a qualitative description of the pore size and membrane morphology in relation to the membrane preparation conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 576–591, 2004
Positive temperature coefficient behavior of polymer composites having a high melting temperature
Authors: Kim Jung‐il , Kang Phil Hyun , Nho Young Chang
Published: February 2004

The positive temperature coefficient (PTC) behavior of polymers having a high melting temperature, such as nylon, polyvinylidene fluoride, polyester, and polyacetal, was investigated. Carbon black and nickel powder were used to investigate the influence of their conductive fillers on PTC intensity. The polymer/filler composite was irradiated with gamma rays at dosages of 50, 100, and 150 kGy for the purpose of reducing the negative temperature coefficient (NTC) of a conductive composite. It was found that the PTC temperature depended on the melting point of the polymer matrix. The crosslinking structure enhanced the electrical stability and decreased the NTC effect of the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 394–401, 2004
Vanishing Flora – Lost Chemistry: The Scents of Endangered Plants around the World
Authors: Kaiser Roman
Published: February 2004

As part of our broad and ongoing evaluation of the olfactory components of fragrant plants and flowers during the past 25 years, we have encountered an astounding number of interestingly scented, but endangered plant species. In appreciation of nature's marvels in these species, we are compiling a report on their scent compositions and complementary information in an upcoming book ‘Vanishing Flora – Lost Chemistry’. In this paper, a few examples of endangered plant species and their scent components are presented as a brief introduction to the concept of the book project.
Non‐Nucleoside Reverse Transcriptase Inhibitors (NNRTIs): Past, Present, and Future
Authors: De Clercq Erik
Published: February 2004

Non‐nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) have become an inherent ingredient of the drug combination schemes that are currently used in the treatment of human immunodeficiency virus type 1 (HIV‐1) infections. Starting from the 1‐[(2‐hydroxyethoxy)methyl]‐6‐(phenylsulfanyl)thymine (HEPT) and 4,5,6,7‐tetrahydroimidazo[4,5,1‐jk][1,4]benzodiazepin‐2(1H)‐one and ‐thione (TIBO) derivatives, numerous classes of compounds have been described as NNRTIs. Only three compounds have so far been approved for clinical use: nevirapine, delavirdine, and efavirenz. NNRTIs are notorious for rapidly leading to virus‐drug resistance development, primarily based on the emergence of the K103N and Y181C mutations in the HIV‐1 RT. Newer NNRTIs, such as capravirine, dapivirine (TMC 125), and DPC 083, are resilient to these ‘NNRTI’ mutations, and, therefore, offer considerable promise as future anti‐HIV‐1 drugs. NNRTIs are targeted at a specific ‘pocket’ binding site within the HIV‐1 RT, that is distinct from, but both spatially and functionally related to, the catalytic site, where the nucleoside RT inhibitors (NRTIs) and nucleotide RT inhibitors (NtRTIs) interact. NNRTIs have acquired a definitive position, as part of a combination regimen with NRTIs and NtRTIs, in the first‐line treatment of HIV‐1 infections.
The Importance of Being Exhaustive. Optimization of Bridging Structural Water Molecules and Water Networks in Models of Biological Systems
Authors: Kellogg Glen E. , Chen Deliang L.
Published: February 2004

Algorithms and protocols are described for the optimization for H‐bonding of isolated singular H2O molecules and entire networks of H2O molecules. Unlike other approaches that are prone to being trapped in local energy minima, these methods rely on exhaustive searches of orientation space for the H2O molecules. The results are scored with the HINT hydropathic interaction model, but the algorithms should be general for any energy‐scoring computation. Two examples are provided: 1) the tightly‐bound H2O molecule 301 of HIV‐1 protease is shown to be more reasonably oriented in terms of forming H‐bonds with this method than with a molecular mechanics energy minimization method; and 2) the H2O network surrounding carbonmonoxymyoglobin is constructed and analyzed for a 1.80‐Å neutron‐diffraction structure. The H‐atom positions calculated with this method show a somewhat better agreement with the experimental results than do the H‐atom positions calculated with molecular mechanics, and both are considerably better than random.
Quadricyclane Radical Cation Rearrangements: A Computational Study of the Transformations to 1,3,5‐Cycloheptatriene and Norbornadiene
Authors: Larsson Per‐Erik , Salhi‐Benachenhou Nessima , Lunell Sten
Published: February 2004

An alternative skeletal rearrangement of the quadricyclane radical cation (Q.+) explains the side products formed in the one‐electron oxidation to norbornadiene. First, the bicyclo[2.2.1]hepta‐2‐ene‐5‐yl‐7‐ylium radical cation, with an activation energy of 14.9 kcal mol−1, is formed. Second, this species can further rearrange to 1,3,5‐cycloheptatriene through two plausible paths, that is, a multistep mechanism with two shallow intermediates and a stepwise path in which the bicyclo[3.2.0]hepta‐2,6‐diene radical cation is an intermediate. The multistep rearrangement has a rate‐limiting step with an estimated activation energy of 16.5 kcal mol−1, which is 2.8 kcal mol−1 lower in energy than the stepwise mechanism. However, the lowest activation energy is found for the Q.+ cycloreversion to norbornadiene that has a transition structure, in close correspondence with earlier studies, and an activation energy of 10.1 kcal mol−1, which agrees well with the experimental estimate of 9.3 kcal mol−1. The computational estimates of activation energies were done using the CCSD(T)/6–311+G(d,p) method with geometries optimized on the B3LYP/6–311+G(d,p) level, combined with B3LYP/6–311+G(d,p) frequencies.
First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach
Authors: Bakhmutova Ekaterina V. , Bakhmutov Vladimir I. , Belkova Natalia V. , Besora Maria , Epstein Lina M. , Lledós Agustí , Nikonov Georgii I. , Shubina Elena S. , Tomàs Jaume , Vorontsov Eugenii V.
Published: February 2004

The interaction of [NbCp2H3] with fluorinated alcohols to give dihydrogen‐bonded complexes was studied by a combination of IR, NMR and DFT methods. IR spectra were examined in the range from 200–295 K, affording a clear picture of dihydrogen‐bond formation when [NbCp2H3]/HORf mixtures (HORf = hexafluoroisopropanol (HFIP) or perfluoro‐tert‐butanol (PFTB)) were quickly cooled to 200 K. Through examination of the OH region, the dihydrogen‐bond energetics were determined to be 4.5±0.3 kcal mol−1 for TFE (TFE = trifluoroethanol) and 5.7±0.3 kcal mol−1 for HFIP. 1H NMR studies of solutions of [NbCp2H${{{\rm B}\hfill \atop 2\hfill}}$HA] and HFIP in [D8]toluene revealed high‐field shifts of the hydrides HA and HB, characteristic of dihydrogen‐bond formation, upon addition of alcohol. The magnitude of signal shifts and T1 relaxation time measurements show preferential coordination of the alcohol to the central hydride HA, but are also consistent with a bifurcated character of the dihydrogen bonding. Estimations of hydride–proton distances based on T1 data are in good accord with the results of DFT calculations. DFT calculations for the interaction of [NbCp2H3] with a series of non‐fluorinated (MeOH, CH3COOH) and fluorinated (CF3OH, TFE, HFIP, PFTB and CF3COOH) proton donors of different strengths showed dihydrogen‐bond formation, with binding energies ranging from −5.7 to −12.3 kcal mol−1, depending on the proton donor strength. Coordination of proton donors occurs both to the central and to the lateral hydrides of [NbCp2H3], the former interaction being of bifurcated type and energetically slightly more favourable. In the case of the strong acid H3O+, the proton transfer occurs without any barrier, and no dihydrogen‐bonded intermediates are found. Proton transfer to [NbCp2H3] gives bis(dihydrogen) [NbCp2(η2‐H2)2]+ and dihydride(dihydrogen) complexes [NbCp2(H)2(η2‐H2)]+ (with lateral hydrides and central dihydrogen), the former product being slightly more stable. When two molecules of TFA were included in the calculations, in addition to the dihydrogen‐bonded adduct, an ionic pair formed by the cationic bis(dihydrogen) complex [NbCp2(η2‐H2)2]+ and the homoconjugated anion pair (CF3COO⋅⋅⋅ H⋅⋅⋅OOCCF3)− was found as a minimum. It is very likely that these ionic pairs may be intermediates in the H/D exchange between the hydride ligands and the OD group observed with the more acidic alcohols in the NMR studies.
Supramolecular Control of Charge‐Transfer Dynamics on Dye‐sensitized Nanocrystalline TiO2 Films
Authors: Hirata Narukuni , Lagref Jean‐Jacques , Palomares Emilio J. , Durrant James R. , Nazeeruddin M. Khaja , Gratzel Michael , Di Censo Davide
Published: February 2004

A [Ru(dcbpy)2(NCS)2] dye has been chemically modified by the addition of a secondary electron donor moiety, N,N‐(di‐p‐anisylamino)phenoxymethyl. Optical excitation of the modified dye adsorbed to nanocrystalline TiO2 films shows a remarkably long‐lived charge‐separated state, with a decay half time of 0.7 s. Semiempirical calculations confirm that the HOMO of the modified dye molecule is localised on the electron donor group. The retardation of the recombination dynamics relative to the unmodified control dye is caused by the increase in the spatial separation of the HOMO orbital from the TiO2 surface. The magnitude of the retardation is shown to be in agreement with that predicted from the non‐adiabatic electron‐tunnelling theory.
A New Family of Dinuclear Rhodium Complexes Containing Tertiary Phosphanes in a Semibridging or Doubly Bridging Bonding Mode
Authors: Pechmann Thomas , Brandt Carsten D. , Werner Helmut
Published: February 2004

The reactions of [Rh2Cl(κ2‐acac)(μ‐CPh2)2(μ‐SbiPr3)] (3) and [Rh2(κ2‐acac)2(μ‐CPh2)2(μ‐SbiPr3)] (4) with PMe3 lead to exchange of the bridging ligand and afford the novel PMe3‐bridged counterparts 5 and 6, in which the phosphane occupies a semibridging (5) or a doubly bridging (6) position. In both cases, the bonding mode was confirmed crystallographically. Treatment of 6 with CO causes a shift of PMe3 from a bridging to a terminal position and gives the unsymmetrical complex [(κ2‐acac)Rh(μ‐CPh2)2(μ‐CO)Rh(PMe3)(κ2‐acac)] (7). Similarly to 5 and 6, the related compounds 10 and 11 with one or two acac‐f3 ligands were prepared. While both PEt3 and PnBu3 react with 3 by exchange of the bridging stibane for phosphane to give compounds 12 and 13, the reactions of 4 with PMePh2 and PnBu3 afford the mixed‐valent Rh0RhII complexes [(PR3)Rh(μ‐CPh2)2Rh(κ2‐acac)2] (17, 18) in high yields. In contrast, treatment of 4 with PEt3 and PMe2Ph generates the phosphane‐bridged compounds [Rh2(κ2‐acac)2(μ‐CPh2)2(μ‐PR3)] (14, 15) exclusively. Stirring a solution of 14 (R=Et) in benzene for 15 h at room temperature leads to complete conversion to the mixed‐valent isomer 16. The reaction of 6 with an equimolar amount of CR3CO2H (R=F, H) or phenol in the molar ratio of 1:10 results in substitution of one acac by one trifluoracetate, acetate, or phenolate ligand without disturbing the [Rh2(μ‐CPh2)2(μ‐PR3)] core. From 6 and an excess of CR3CO2H, the symmetrical bis(trifluoracetato) and bis(acetate) derivatives [Rh2(κ2‐O2CCR3)2(μ‐CPh2)2(μ‐PMe3)] (21, 22) were obtained.