diff --git a/admin-ui/src/main/java/eu/knowledge/engine/admin/MetadataKB.java b/admin-ui/src/main/java/eu/knowledge/engine/admin/MetadataKB.java
index 5937bc951..0a9421bfd 100644
--- a/admin-ui/src/main/java/eu/knowledge/engine/admin/MetadataKB.java
+++ b/admin-ui/src/main/java/eu/knowledge/engine/admin/MetadataKB.java
@@ -6,6 +6,7 @@
 
 import org.apache.jena.rdf.model.Model;
 import org.apache.jena.rdf.model.Resource;
+import org.apache.jena.rdf.model.ResourceFactory;
 import org.apache.jena.shared.PrefixMapping;
 import org.apache.jena.sparql.graph.PrefixMappingMem;
 import org.apache.jena.sparql.lang.arq.javacc.ParseException;
@@ -125,6 +126,7 @@ public BindingSet handleNewKnowledgeBase(ReactExchangeInfo ei) {
 
 			Resource kb = model.listSubjectsWithProperty(RDF.type, Vocab.KNOWLEDGE_BASE).next();
 			this.metadata.add(model);
+			model.close();
 			LOG.debug("Modified metadata with new KB '{}'.", kb);
 		} catch (ParseException e) {
 			LOG.error("{}", e);
@@ -155,6 +157,8 @@ public BindingSet handleChangedKnowledgeBase(ReactExchangeInfo ei) {
 
 			this.metadata.add(model);
 
+			model.close();
+
 			LOG.debug("Modified metadata with changed KB '{}'.", kb);
 
 		} catch (ParseException e) {
@@ -167,26 +171,23 @@ public BindingSet handleRemovedKnowledgeBase(ReactExchangeInfo ei) {
 		if (!this.canReceiveUpdates())
 			return new BindingSet();
 
-		try {
-			Model model = eu.knowledge.engine.smartconnector.impl.Util.generateModel(this.aKI.getPattern(),
-					ei.getArgumentBindings());
+		// this is also a little complex... we have to:
+		// - extract the knowledge base that this message is about
+		// - delete all old data about that knowledge base
 
-			// this is also a little complex... we have to:
-			// - extract the knowledge base that this message is about
-			// - delete all old data about that knowledge base
+		String kbUri = ei.getArgumentBindings().iterator().next().get("kb");
+		Resource kb = this.metadata.createResource(kbUri.substring(1, kbUri.length() - 1));
 
-			Resource kb = model.listSubjectsWithProperty(RDF.type, Vocab.KNOWLEDGE_BASE).next();
-			String query = String.format("DELETE { %s } WHERE { %s FILTER (?kb = <%s>) } ",
-					this.metaGraphPattern.getPattern(), this.metaGraphPattern.getPattern(), kb.toString());
+		LOG.info("KB '{}'.", kb);
 
-			UpdateRequest updateRequest = UpdateFactory.create(query);
-			UpdateAction.execute(updateRequest, this.metadata);
+		String query = String.format("DELETE { %s } WHERE { %s FILTER (?kb = <%s>) } ",
+				this.metaGraphPattern.getPattern(), this.metaGraphPattern.getPattern(), kb.toString());
 
-			LOG.debug("Modified metadata with deleted KB '{}'.", kb);
+		UpdateRequest updateRequest = UpdateFactory.create(query);
+		UpdateAction.execute(updateRequest, this.metadata);
+
+		LOG.debug("Modified metadata with deleted KB '{}'.", kb);
 
-		} catch (ParseException e) {
-			LOG.error("{}", e);
-		}
 		return new BindingSet();
 	}
 
@@ -198,6 +199,10 @@ public void fetchInitialData() {
 			// execute actual *ask* and use previously defined Knowledge Interaction.
 			this.getSC().ask(this.aKI, new BindingSet()).thenAccept(askResult -> {
 				try {
+
+					if (this.metadata != null)
+						this.metadata.close();
+
 					// using the BindingSet#generateModel() helper method, we can combine the graph
 					// pattern and the bindings for its variables into a valid RDF Model.
 					this.metadata = eu.knowledge.engine.smartconnector.impl.Util.generateModel(this.aKI.getPattern(),
diff --git a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/MetaKnowledgeBaseImpl.java b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/MetaKnowledgeBaseImpl.java
index 8ee436d3a..a34e878da 100644
--- a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/MetaKnowledgeBaseImpl.java
+++ b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/MetaKnowledgeBaseImpl.java
@@ -527,6 +527,8 @@ private OtherKnowledgeBase constructOtherKnowledgeBaseFromBindingSet(BindingSet
 
 		}
 
+		model.close();
+
 		URI kbId = null;
 		try {
 			kbId = new URI(kb.getURI());
diff --git a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/Util.java b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/Util.java
index ee214c274..79a86b4fc 100644
--- a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/Util.java
+++ b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/impl/Util.java
@@ -10,7 +10,7 @@
 import javax.cache.CacheManager;
 import javax.cache.Caching;
 import javax.cache.configuration.MutableConfiguration;
-import javax.cache.expiry.CreatedExpiryPolicy;
+import javax.cache.expiry.AccessedExpiryPolicy;
 import javax.cache.expiry.Duration;
 import javax.cache.spi.CachingProvider;
 
@@ -40,7 +40,7 @@ public class Util {
 		CacheManager cacheManager = cachingProvider.getCacheManager();
 		MutableConfiguration<String, Node> config = new MutableConfiguration<String, Node>()
 				.setTypes(String.class, Node.class).setStoreByValue(false)
-				.setExpiryPolicyFactory(CreatedExpiryPolicy.factoryOf(Duration.ONE_HOUR));
+				.setExpiryPolicyFactory(AccessedExpiryPolicy.factoryOf(Duration.TEN_MINUTES));
 		nodeCache = cacheManager.createCache("nodeCache", config);
 	}
 
@@ -100,7 +100,7 @@ public static Model generateModel(GraphPattern graphPattern, BindingSet variable
 		}
 		return m;
 	}
-	
+
 	public static Set<TriplePattern> translateGraphPatternTo(GraphPattern pattern) {
 
 		TriplePattern tp;
diff --git a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/util/KnowledgeBaseImpl.java b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/util/KnowledgeBaseImpl.java
index c6bd02293..3082af347 100644
--- a/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/util/KnowledgeBaseImpl.java
+++ b/smart-connector/src/main/java/eu/knowledge/engine/smartconnector/util/KnowledgeBaseImpl.java
@@ -303,6 +303,7 @@ public boolean isUpToDate(AskKnowledgeInteraction askKnowledgeInteraction,
 					isUpToDate &= isKnowledgeBaseUpToDate(aKnowledgeBase, m);
 				}
 			}
+			m.close();
 
 		} catch (InterruptedException | ExecutionException | ParseException e) {
 			LOG.error("{}", e);