Production of methyl ethyl ketone from biomass using a hybrid biochemical/catalytic approach

The recent demand for sustainable routes to fuels and chemicals has led to an increased amount of research in conversion of natural resources. A potential approach for conversion of biomass to fuels and chemicals is to combine biochemical and chemical processes. This research used microbial fermentation to produce 2,3-butanediol, which was then converted to methyl ethyl ketone by dehydration over a solid acid catalyst. The fermentation process was performed using the bacteria Klebsiella oxytoca (K.O). 2,3-butanediol then dehydrated to form methyl ethyl ketone on a solid acid catalyst, the proton form of ZSM-5, and heat. The goal was to determine the reaction kinetics of 2,3-butanediol dehydration over ZSM-5, and to demonstrate the hybrid biochemical/thermochemical approach for synthesizing chemicals from biomass. It was found that ZSM-5 produced methyl ethyl ketone with high selectivity (greater than 90%), and could convert fermentative 2,3-butanediol to methyl ethyl ketone. The reaction order of 2,3-butanediol dehydration was found to be slightly large than one, and an activation energy of 32.3 kJ/mol was measured

D-lactic acid biosynthesis from biomass-derived sugars via Lactobacillus delbrueckii fermentation

Poly-lactic acid (PLA) derived from renewable resources is considered to be a good substitute for petroleum-based plastics. The number of poly L-lactic acid applications is increased by the introduction of a stereocomplex PLA, which consists of both poly-L and D-lactic acid and has a higher melting temperature. To date, several studies have explored the production of L-lactic acid, but information on biosynthesis of D-lactic acid is limited. Pulp and corn stover are abundant, renewable lignocellulosic materials that can be hydrolyzed to sugars and used in biosynthesis of D-lactic acid. In our study, saccharification of pulp and corn stover was done by cellulase CTec2 and sugars generated from hydrolysis were converted to D-lactic acid by a homofermentative strain, L. delbrueckii, through a sequential hydrolysis and fermentation process (SHF) and a simultaneous saccharification and fermentation process (SSF). 36.3 g Lˉ¹ of D-lactic acid with 99.8 % optical purity was obtained in the batch fermentation of pulp and attained highest yield and productivity of 0.83 g gˉ¹ and 1.01 g Lˉ¹ hˉ¹, respectively. Luedeking–Piret model described the mixed growth-associated production of D-lactic acid with a maximum specific growth rate 0.2 hˉ¹ and product formation rate 0.026 hˉ¹, obtained for this strain. The efficient synthesis of D-lactic acid having high optical purity and melting point will lead to unique stereocomplex PLA with innovative applications in polymer industry

Cellulolytic Enzymes Production via Solid-State Fermentation: Effect of Pretreatment Methods on Physicochemical Characteristics of Substrate

We investigated the effect of pretreatment on the physicochemical characteristics—crystallinity, bed porosity, and volumetric specific surface of soybean hulls and production of cellulolytic enzymes in solid-state fermentation of Trichoderma reesei and Aspergillus oryzae cultures. Mild acid and alkali and steam pretreatments significantly increased crystallinity and bed porosity without significant change inholocellulosic composition of substrate. Crystalline and porous steam-pretreated soybean hulls inoculated with T. reesei culture had 4 filter paper units (FPU)/g-ds, 0.6 IU/g-ds β-glucosidase, and 45 IU/g-ds endocellulase, whereas untreated hulls had 0.75 FPU/g-ds, 0.06 IU/g-ds β-glucosidase, and 7.29 IU/g-ds endocellulase enzyme activities. In A. oryzae steam-pretreated soybean hulls had 47.10 IU/g-ds endocellulase compared to 30.82 IU/g-ds in untreated soybean hulls. Generalized linear statistical model fitted to enzyme activity data showed that effects of physicochemical characteristics on enzymes production were both culture and enzyme specific. The paper shows a correlation between substrate physicochemical properties and enzyme production

A rare case of iii cranial nerve palsy - mucormycosis involving the right maxillary and ethmoidal sinus

IIIrd Cranial nerve palsy, known as oculomotor nerve palsy, may result from various causes, however, the etiology remains unknown in some instances. This case report aims to present the authors' experience with a case of IIIrd cranial nerve palsy, together with a review of the literature. Many etiologies have been associated with isolated oculomotor nerve palsies. We report the case of a patient who presented with right maxillary and ethmoidal sinusitis with IIIrd cranial nerve palsy associated with mucormycosis. Careful examinations to rule out other causes must be done and then treatment with antifungals should be considered after early diagnosis

Evaluation of knowledge, experience and perceptions about medical emergencies amongst dental graduates (Interns) of Belgaum City, India

Introduction: Medical emergencies can occur frequently in dental setting. Effective management of an emergency situation in the dental office is ultimately the dentist's responsibility. The lack of training and inability to cope with medical emergencies can lead to tragic consequences and sometimes legal action. For this reason, all health professionals including dentists must be well prepared to attend to medical emergencies. Providing basic life support [BLS] is dentist's most important contribution until definitive treatment for a medical emergency can be given. Hence the study is aimed to assess the dental graduates (Interns) knowledge, skills and competency regarding dentistry-medical emergency interface. Methodology: Data were collected from 105 Interns of two dental colleges of Belgaum City using a structured questionnaire consisting of 7 item questionnaire (6 closed and 1 open ended). Results: Overall in all the years, syncope / faint was seen by 40.9% of the respondents, 37.1% with hypoglycemic attacks, allergic reactions by 17.1%, epileptic attacks by 7.6%, asthmatic attacks by 4.5% and angina 0.9%. The frequencies of the emergencies encountered were once or even more. Knowledge of the presence of drugs and equipments in the emergency drug kit and the confidence in regard to use them was low. Medical emergencies training were undertaken by 42% respondents, but in varying degrees. There was a desire for further medical emergencies training by majority of respondents. Conclusion: The study showed that syncope is the commonest medical emergency event. Dental graduates had a superficial knowledge of medical emergencies, drugs and equipments. Emphasis is placed on the need for more medical emergencies training to be offered, to increase knowledge and confidence of dental graduates (Interns) in the management of medical emergencie